Splice variants associated with neomorphic SF3B1 mutants

The present application is a continuation of U.S. patent application Ser. No. 15/755,225, filed Feb. 26, 2018, which is a national stage application under 35 U.S.C. § 371 of international application number PCT/US2016/049490, filed Aug. 30, 2016, which designated the U.S. and claims the benefit of priority to U.S. Provisional Patent Application No. 62/212,876, filed Sep. 1, 2015, the contents of which are hereby incorporated by reference herein in their entirety.

The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. The ASCII copy, created on May 16, 2014, is named 12636.6-304_ SL.txt and is 183 kilobytes in size.

RNA splicing, a highly regulated molecular event orchestrated by the spliceosome, results in the removal of intronic sequences from pre-mRNA to generate mature mRNA. Dysregulation of RNA splicing has been identified as a causative defect in several diseases. In addition, dysregulated splicing has been proposed to play an important role in tumorigenesis and resistance to therapy; however, the molecular causes of dysregulated splicing in cancer have remained elusive.

SF3B1 is a protein involved in RNA splicing. It forms part of the U2 snRNP complex which binds to the pre-mRNA at a region containing the branchpoint site and is involved in early recognition and stabilization of the spliceosome at the 3′ splice site (3′ss). A thorough and systematic analysis of the effects of SF3B1 mutations is needed to define their effects on RNA splicing in cells and may lead to novel therapeutic approaches for SF3B1 mutant cancers.

The description provided herein demonstrates that certain SF3B1 mutations result in neomorphic activity with the production of known and novel splicing alterations. In addition, lineage-specific splicing aberrations were identified in chronic lymphocytic leukemia (CLL), melanoma, and breast cancer. Furthermore, treatment of SF3B1-mutant cancer cell lines, xenografts, and CLL patient samples with modulators of SF3B1 reduced aberrant splicing and induced tumor regression.

The methods described herein involve detecting or quantifying the expression of one or more splice variants in a cell containing a neomorphic mutant SF3B1 protein. Various embodiments of the invention include detecting or quantifying splice variants to determine whether a patient has a cancer with one or more neomorphic SF3B1 mutations. Additional embodiments include measuring the amount of a splice variant to evaluate the effects of a compound on a mutant SF3B1 protein. Further embodiments include methods of treating a patient who has cancer cells with a neomorphic mutant SF3B1 protein.

Various embodiments encompass a method of detecting one or more splice variants selected from rows 1-790 of Table 1 in a biological sample, comprising:

a) providing a biological sample suspected of containing one or more splice variants;

b) contacting the biological sample with one or more nucleic acid probes capable of specifically hybridizing to the one or more splice variants, and

c) detecting the binding of the one or more probes to the one or more splice variants.

In some embodiments, the one or more nucleic acid probes capable of specifically hybridizing to the one or more splice variants each comprise a label. In some embodiments, the method of detecting one or more splice variants selected from rows 1-790 of Table 1 in a biological sample further comprises contacting the biological sample with one or more additional nucleic acid probes, wherein the additional probes are each labeled with a molecular barcode.

Embodiments further encompass a method of modulating the activity of a neomorphic mutant SF3B1 protein in a target cell, comprising applying an SF3B1-modulating compound to the target cell, wherein the target cell has been determined to express one or more aberrant splice variants selected from rows 1-790 of Table 1 at a level that is increased or decreased relative to the level in a cell not having the neomorphic mutant SF3B1 protein.

Embodiments also encompass a method for evaluating the ability of a compound to modulate the activity of a neomorphic mutant SF3B1 protein in a target cell, comprising the steps of:

a) providing a target cell having a mutant SF3B1 protein;

b) applying the compound to the target cell; and

c) measuring the expression level of one or more splice variants selected from row 1-790 of Table 1.

In some embodiments, the method for evaluating the ability of a compound to modulate the activity of a neomorphic mutant SF3B1 protein in a target cell further comprises the step of measuring the expression level of one or more splice variants selected from row 1-790 of Table 1 before step (b).

In some embodiments, the neomorphic mutant SF3B1 protein is selected from K700E, K666N, R625C, G742D, R625H, E622D, H662Q, K666T, K666E, K666R, G740E, Y623C, T663I, K741N, N626Y, T663P, H662R, G740V, D781E, or R625L. In some embodiments, the neomorphic mutant SF3B1 protein is selected from E622D, E622K, E622Q, E622V, Y623C, Y623H, Y623S, R625C, R625G, R625H, R625L, R625P, R625S, N626D, N626H, N626I, N626S, N626Y, H662D, H662L, H662Q, H662R, H662Y, T663I, T663P, K666E, K666M, K666N, K666Q, K666R, K666S, K666T, K700E, V701A, V701F, V701I, I704F, I704N, I704S, I704V, G740E, G740K, G740R, G740V, K741N, K741Q, K741T, G742D, D781E, D781G, or D781N.

In some embodiments, the step of measuring the expression level of one or more splice variants comprises using an assay to quantify nucleic acid selected from nucleic acid barcoding (e.g. NanoString®), RT-PCR, microarray, nucleic acid sequencing, nanoparticle probes (e.g. SmartFlare™), and in situ hybridization (e.g. RNAscope®).

In some embodiments, the step of measuring the expression level of one or more splice variants comprises measuring the number of copies of the one or more splice variant RNAs in the target cell.

In further embodiments, the compound is selected from a small molecule, an antibody, an antisense molecule, an aptamer, an RNA molecule, and a peptide. In further embodiments, the small molecule is selected from pladienolide and a pladienolide analog. In additional embodiments, the pladienolide analog is selected from pladienolide B, pladienolide D, E7107, a compound of formula 1:

a compound of formula 2:

a compound of formula 3:

or a compound of formula 4:

In some embodiments, the target cell is obtained from a patient suspected of having myelodysplastic syndrome, chronic lymphocytic leukemia, chronic myelomonocytic leukemia, or acute myeloid leukemia. In some embodiments, the target cell is obtained from a sample selected from blood or a blood fraction or is a cultured cell derived from a cell obtained from a sample chosen from blood or a blood fraction. In some embodiments, the target cell is a lymphocyte.

In further embodiments, the target cell is obtained from a solid tumor. In some embodiments, the target cell is a breast tissue cell, pancreatic cell, lung cell, or skin cell.

In some embodiments, one or more of the aberrant variants are selected from rows 1, 7, 9, 10, 13, 15, 16, 18, 21, 24, 27, 28, 30, 31, 33, 34, 48, 51, 62, 65, 66, 71, 72, 81, 84, 89, 91, 105, 107, 121, 135, 136, 152, 178, 235, 240, 247, 265, 267, 272, 276, 279, 282, 283, 286, 292, 295, 296, 298, 302, 306, 329, 330, 331, 343, 350, 355, 356, 360, 364, 372, 378, 390, 391, 423, 424, 425, 426, 431, 433, 438, 439, 443, 445, 447, 448, 451, 452, 458, 459, 460, 462, 468, 469, 472, 500, 508, 517, 519, 521, 524, 525, 527, 528, 530, 533, 536, 540, 543, 548, 545, 554, 556, 559, 571, 573, 580, 582, 583, 597, 601, 615, 617, 618, 639, 640, 654, 657, 666, 670, 680, 727, 730, 750, 758, 767, or 774 of Table 1.

In some embodiments, one or more of the aberrant variants are selected from rows 21, 31, 51, 81, 118, 279, 372, 401, 426, 443, 528, 543, 545, 548 or 566 of Table 1.

Embodiments further encompass a method for treating a patient with a neoplastic disorder, comprising administering a therapeutically effective amount of an SF3B1-modulating compound to the patient, wherein a cell from the patient has been determined to:

a) contain a neomorphic mutant SF3B1 protein; and

b) express one or more aberrant splice variants selected from rows 1-790 of Table 1 at a level that is increased or decreased relative to the level in a cell not having the neomorphic mutant SF3B1 protein.

Additional embodiments are set forth in the description which follows.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

FIG. 1 is a schematic diagram depicting modes of alternative splicing.

FIG. 2 is a graph depicting levels of gene expression for abnormally spliced genes across different cancers in patient samples.

FIG. 3 is a schematic diagram showing the locations of certain neomorphic mutations in the SF3B1 protein and corresponding coding regions of the SF3B1 gene.

FIG. 4 is a graph depicting levels of aberrant splice variants detected in RNA isolated from pancreatic, lung cancer, and Nalm-6 isogenic cell lines using a NanoString® assay. Data are represented as the mean of three replicates.

FIG. 5 is a set of western blot images that confirm overexpression of SF3B1 proteins in 293FT cells.

FIG. 6 is a graph depicting levels of aberrant splice variants in RNA isolated from 293FT cells expressing wild type SF3B1 (SF3B1 WT ) or mutant SF3B1 proteins, as measured in a NanoString® assay. Data are represented as the mean of three replicates.

FIG. 7 is a set of western blot images that confirm overexpression of SF3B1 proteins in 293FT cells.

FIG. 8 is a graph depicting levels of aberrant splice variants in RNA isolated from 293FT cells expressing SF3B1 WT or mutant SF3B1 proteins, as measured in a NanoString® assay.

FIG. 9 A depicts a set of western blot images showing expression of SF3B1 alleles before and after shRNA-knockdown in Panc 05.04 cells. FIG. 9 B depicts a graph showing levels of SF3B1 RNA detected by qPCR in Panc 05.04 cells before and after shRNA-knockdown of all SF3B1 alleles (“SF3B1 PAN ) or SF3B1 WT or mutant SF3B1 (SF3B1 MUT ) alleles. qPCR data are represented as fold change relative to pLKO non-treated with doxycycline (mean±SD, n=3). Solid black, outlined, and gray bars indicate SF3B1 PAN , SF3B1 WT , and SF3B1 MUT allele-specific qPCR data, respectively.

FIG. 10 A depicts a set of western blot images showing expression of SF3B1 alleles before and after shRNA-knockdown in Panc 10.05 cells. FIG. 10 B depicts a graph showing levels of SF3B1 RNA detected by qPCR in Panc 10.05 cells before and after shRNA-knockdown of SF3B1 alleles. qPCR data are represented as fold change relative to pLKO non-treated with doxycycline (mean±SD, n=3). Solid black, outlined, and gray bars indicate SF3B1 PAN , SF3B1 WT , and SF3B1 MUT allele-specific qPCR data, respectively.

FIGS. 11 A and 11 B are a set of graphs depicting levels of splice variants in Panc 05.04 ( FIG. 11 A ) and Panc 10.05 cells ( FIG. 11 B ) before and after shRNA-knockdown of SF3B1 alleles, as measured in a NanoString® assay. Data are represented as mean of three biological replicates.

FIG. 12 is a set of graphs depicting growth curves of Panc 05.04 cells before (circles) and after (squares) shRNA-knockdown of SF3B1 alleles.

FIG. 13 is a set of graphs depicting growth curves of Panc 10.05 cells before (circles) and after (squares) shRNA-knockdown of SF3B1 alleles.

FIGS. 14 A and 14 B are a set of images of culture plates showing colony formation of Panc 05.04 cells ( FIG. 14 A ) and Panc 10.05 ( FIG. 14 B ) cells before and after shRNA-knockdown of SF3B1 alleles.

FIGS. 15 A and 15 B are a set of graphs showing the level of splicing of pre-mRNA Ad2 substrate in nuclear extracts from ( FIG. 15 A ) 293F cells expressing Flag-tag SF3B1 WT or SF3B1 K700E (left and right panels [circles and triangles], respectively) and ( FIG. 15 B ) Nalm-6 (SF3B1 WT ) and Nalm-6 SF3B1 K700E cells (left and right panels [circles and triangles], respectively) treated with varying concentrations of E7101. Data are represented as mean±SD, n=2.

FIG. 16 A depicts a pair of graphs showing the binding of a radiolabeled E7107 analog to either SF3B1 WT (circles, left panel) or SF3B1 K700E (triangles, right panel) after incubation of the proteins with varying concentrations of E7107. FIG. 16 B depicts upper panels, a pair of graphs showing the levels of EIF4A1 pre-mRNA (squares) and SLC25A19 mature RNA (inverted triangles) in Nalm-6 SF3B1 K700K cells (left panel) and Nalm-6 SF3B1 K700E cells (right panel) treated with varying concentrations of E7107, as measured by qPCR. FIG. 16 B depicts lower panels, a pair of graphs showing the levels of abnormally spliced isoforms of abnormally spliced genes COASY (triangles) and ZDHHC16 (diamonds) in Nalm-6 SF3B1 K700K cells (left panel) and Nalm-6 SF3B1 K700E cells (right panel) treated with varying concentrations of E7107, as measured by qPCR. qPCR data in ( FIG. 16 B ) are represented as mean±SD (n=3).

FIG. 17 is a set of graphs depicting levels of splice variants in Nalm-6 SF3B1 K700K and Nalm-6 SF3B1 K700E cells after treatment of cells with E7107 for two or six hours, as measured in a NanoString® assay. Data are expressed as fold change from DMSO-only treatment

FIG. 18 is a set of graphs depicting levels of splice variants in Nalm-6 SF3B1 K700K and Nalm-6 SF3B1 K700E cells after treatment of cells with E7107 for six hours, as measured by RNA-Seq analysis.

FIG. 19 is a set of graphs depicting levels of splice variants in Nalm-6 SF3B1 K700K and Nalm-6 SF3B1 K700E cells after treatment of cells with the numbered compounds indicated above the graphs, as measured by RNA-Seq analysis.

FIG. 20 is set of graphs depicting levels of splice variants in Nalm-6 SF3B1 K700K and Nalm-6 SF3B1 K700E cells at varying times following treatment of cells with E7107, as measured by qPCR of RNA. Data are represented as mean±SD (n=3). The upper panels of FIG. 20 depict the levels of EIF4A1 pre-mRNA (squares) and SLC25A19 mature RNA (inverted triangles) in Nalm-6 SF3B1 K700K cells (left panel) and Nalm-6 SF3B1 K700E cells (right panel) detected at certain times after treatment with E7107. The lower panels of FIG. 20 depict the levels of abnormally spliced isoforms of abnormally spliced genes COASY (triangles) and ZDHHC16 (diamonds) in Nalm-6 SF3B1 K700K cells (left panel) and Nalm-6 SF3B1 K700E cells (right panel) detected at certain times after treatment with E7107. Open circles show the concentration of E7107 (in μg/ml [right vertical axis]) as determined by mass spectrometry of tumor samples.

FIG. 21 is a set of graphs depicting levels of canonical and aberrant splice variants in Nalm-6 SF3B1 K700K - and Nalm-6 SF3B1 K700E -xenograft tumors (left and right sets of panels, respectively) at certain timepoints after treatment of xenograft mice with E7107, as measured in a NanoString® assay. Data are represented as mean of three replicates.

FIG. 22 is a set of graphs depicting levels of canonical and aberrant splice variants in Panc 05.04-xenograft tumors at certain timepoints after treatment of xenograft mice with E7107 at various concentrations, as measured in a NanoString® assay (n=4 mice for each group).

FIG. 23 is a graph depicting tumor volume (shown as mean±SEM) in Nalm-6 SF3B1 K700E -xenograft mice following treatment with E7107, with control mice treated with vehicle shown by open circles (n=10 animals for each group). For E7107-treated animals, inverted triangles=1.25 mg/kg, triangles=2.5 mg/kg, and squares=5 mg/kg.

FIG. 24 is a graph depicting survival rates in 10-animal cohorts of Nalm-6 SF3B1 K700E -xenograft mice following treatment with E7107, with an untreated cohort shown by the solid black line. For E7107-treated animals, dashed line=1.25 mg/kg, gray line=2.5 mg/kg, and dotted line=5 mg/kg.

FIG. 25 is set of graphs depicting levels of splice variants in SF3B1 WT and neomorphic SF3B1 mutant CLL cell samples following treatment with 10 nM E7107 for 6 hours, as measured by analysis. Data are represented as mean values (n=3).

In certain aspects, the methods of the invention provide assays for measuring the amount of a splice variant in a cell, thereby determining whether a patient has a cancer with a neomorphic SF3B1 mutation. In some embodiments, at least one of the measured splice variants is an aberrant splice variant associated with a neomorphic mutation in an SF3B1 protein. In additional aspects, the measurement of a splice variant in a cell may be used to evaluate the ability of a compound to modulate a mutant neomorphic SF3B1 protein in a cell.

To assist in understanding the present invention, certain terms are first defined. Additional definitions are provided throughout the application.

As used herein, the term “mutant SF3B1 protein” includes SF3B1 proteins that differ in amino acid sequence from the human wild type SF3B1 protein set forth in SEQ ID NO:1200 (GenBank Accession Number NP_036565, Version NP_036565.2) (S. Bonnal, L. Vigevani, and J. Valcárcel, “The spliceosome as a target of novel antitumour drugs,” Nat. Rev. Drug Discov. 11:847-59 [2012]). Certain mutant SF3B1 proteins are “neomorphic” mutants, which refers to mutant SF3B1 proteins that are associated with differential expression of aberrant splice variants. In certain embodiments, neomorphic SF3B1 mutants include K700E, K666N, R625C, G742D, R625H, E622D, H662Q, K666T, K666E, K666R, G740E, Y623C, T663I, K741N, N626Y, T663P, H662R, G740V, D781E, or R625L. In other embodiments, neomophic SF3B1 mutants include E622D, E622K, E622Q, E622V, Y623C, Y623H, Y623S, R625C, R625G, R625H, R625L, R625P, R625S, N626D, N626H, N626I, N626S, N626Y, H662D, H662L, H662Q, H662R, H662Y, T663I, T663P, K666E, K666M, K666N, K666Q, K666R, K666S, K666T, K700E, V701A, V701F, V701I, I704F, I704N, I704S, I704V, G740E, G740K, G740R, G740V, K741N, K741Q, K741T, G742D, D781E, D781G, or D781N. Certain SF3B1 mutations are not associated with expression of aberrant splice variants, including K700R.

The term “splice variant” as used herein includes nucleic acid sequences that span a junction either between two exon sequences or across an intron-exon boundary in a gene, where the junction can be alternatively spliced. Alternative splicing includes alternate 3′ splice site selection (“3′ss”), alternate 5′ splice site selection (“5′ss”), differential exon inclusion, exon skipping, and intron retention ( FIG. 1 ). Certain splice variants associated with a given genomic location may be referred to as wild type, or “canonical,” variants. These splice variants are most abundantly expressed in cells that do not contain a neomorphic SF3B1 mutant protein. Additional splice variants may be referred to as “aberrant” splice variants, which differ from the canonical splice variant and are primarily associated with the presence of a neomorphic SF3B1 mutant protein in a cell. Aberrant splice variants may alternatively be referred to as “abnormal” or “noncanonical” splice variants. In certain circumstances, cells with a wild type or non-neomorphic SF3B1 protein have low or undetected amounts of an aberrant splice variant, while cells with a neomorphic SF3B1 protein have levels of an aberrant splice variant that are elevated relative to the low or undetected levels in the wild type SF3B1 cells. In some cases, an aberrant splice variant is a splice variant that is present in a wild type SF3B1 cell but is differentially expressed in a cell that has a neomorphic SF3B1 mutant, whereby the latter cell has a level of the aberrant splice variant that is elevated or reduced relative to the level in the wild type SF3B1 cell. Different types of cells containing a neomorphic SF3B1 mutant, such as different types of cancer cells, may have differing levels of expression of certain aberrant splice variants. In addition, certain aberrant splice variants present in one type of cell containing a neomorphic SF3B1 mutant may not be present in other types of cells containing a neomorphic SF3B1 mutant. In some cases, patients with a neomorphic SF3B1 mutant protein may not express an aberrant splice variant or may express an aberrant splice variant at lower levels, due to low allelic frequency of the neomorphic SF3B1 allele. The identity and relative expression levels of aberrant splice variants associated with various types of cells containing neomorphic SF3B1 mutants, such as certain cancer cells, will be apparent from the description and examples provided herein.

The term “evaluating” includes determining the ability of a compound to treat a disease associated with a neomorphic SF3B1 mutation. In some instances, “evaluating” includes determining whether or to what degree a compound modulates aberrant splicing events associated with a neomorphic SF3B1 protein. Modulation of the activity of an SF3B1 protein may encompass up-regulation or down-regulation of aberrant splice variant expression associated with a neomorphic SF3B1 protein. Additionally, “evaluating” includes distinguishing patients that may be successfully treated with a compound that modulates the expression of splice variants associated with a neomorphic SF3B1 protein.

The use of the word “a”, “an” or “the” when used in conjunction with the term “comprising” in the claims or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” “Or” is to be read inclusively to mean “and/or” unless explicitly indicated to refer to alternatives only, such as where alternatives are mutually exclusive.

Splice Variants

Splice variants of the invention are listed in Table 1. Table 1 provides the genomic location of each canonical (“WT”) and aberrant (“Ab.”) splice junction, as well as the sequence. Each sequence listed in the table contains 20 nucleotides from each of the 3′ and 5′ sides of a splice junction (i.e., the splice junction is at the midpoint of the listed nucleotide sequence). The “Avg WT %” and “Avg Ab. %” columns provide the average percentage count that the canonical (WT) or aberrant splice variant, respectively, represented out of the total counts of all splice variants that utilize a shared splice site, where the counts were determined as set forth in Example 1. The “Log 2 Fold Change” column provides the log 2 of the fold change observed between percentage counts of canonical and aberrant cohorts (see Example 1). The “FDR Q-Value” column provides, as a measure of statistical significance, q-values calculated using the Benjamin-Hochberg procedure from p-values, which in turn were determined using the moderated t-test defined in the Bioconductor's limma package (see Example 1). The “Event” column indicates the nature of the aberrant splice variant, where “3′ss” indicates alternate 3′ splice site selection, “5′ss” indicates alternate 5′ splice site selection, “exon incl.” indicates differential exon inclusion, and “exon skip” indicates exon skipping. The “Type” column refers to the cancer type of the sample in which the aberrant splice variant was identified, where “Br.” indicates breast cancer, “CLL” indicates chronic lymphocytic leukemia, and “Mel.” indicates melanoma.

Certain splice variants are associated with more than one disease, and thus appear in Table 1 more than one time. In certain instances, splice variants associated with more than one cancer type may have different expression levels in each disease, so there may be more than one set of expression data for a given splice variant. Variants differentially expressed across all tested cancer types can be used to evaluate cells having SF3B1 neomorphic mutations in additional cancer types. Such variants are shown in the following rows of Table 1 (triplicates represent the same splice junction, measured in different cancer types): [13, 272, 525], [27, 286, 527], [33, 536, 330], [107, 445, 657], [28, 350, 573], [229, 762, 467], [240, 508, 767], [7, 356, 524], [76, 374, 596], [35, 547, 280], [84, 364, 571], [85, 564, 297], [24, 597, 296], [21, 372, 545], [36, 576, 407], [105, 423, 639], [62, 580, 447], [31, 279, 528], [235, 758, 439], [306, 89, 666], [34, 295, 533], [390, 72, 640], [48, 343, 554], [360, 65, 540], [178, 329, 750], [71, 265, 556], [15, 283, 530], [18, 267, 583], [129, 418, 622], [333, 25, 541], [247, 500, 774], [259, 5, 542], [152, 438, 615], [292, 1, 517], [81, 543, 443], [347, 70, 592], [91, 431, 617], [30, 298, 582], [17, 334, 602], [16, 276, 559], [51, 426, 548], [118, 401, 566], [83, 435, 574], and [269, 45, 546]. In certain embodiments, variants that are nonspecific to a particular cancer type can be chosen from the following rows of Table 1: [13, 272, 525], [27, 286, 527], [33, 536, 330], [107, 445, 657], [28, 350, 573], [240, 508, 767], [7, 356, 524], [84, 364, 571], [24, 597, 296], [21, 372, 545], [105, 423, 639], [62, 580, 447], [31, 279, 528], [235, 758, 439], [306, 89, 666], [34, 295, 533], [390, 72, 640], [360, 65, 540], [178, 329, 750], [71, 265, 556], [15, 283, 530], [18, 267, 583], [247, 500, 774], [152, 438, 615], [292, 1, 517], [81, 543, 443], [91, 431, 617], [30, 298, 582], [16, 276, 559], or [51, 426, 548].

Certain embodiments of the invention provide splice variants as markers for cancer. In certain circumstances, cancer cells with a neomorphic SF3B1 protein demonstrate differential expression of certain splice variants compared to cells without a neomorphic SF3B1 protein. The differential expression of one or more splice variants therefore may be used to determine whether a patient has cancer with a neomorphic SF3B1 mutation. In certain embodiments, the patient is also determined to have a cancer cell having a mutant SF3B1 protein. In these methods, one or more of the splice variants listed in Table 1 can be measured to determine whether a patient has cancer with a neomorphic SF3B1 mutation. In certain embodiments, one or more aberrant splice variants from Table 1 are measured. In other embodiments, one or more canonical splice variants are measured. Sometimes, both aberrant and canonical variants are measured.

In some embodiments, one or more aberrant splice variants selected from rows 260, 262, 263, 265, 266, 267, 272, 273, 275, 276, 277, 279, 281, 282, 286, 287, 288, 290, 294, 295, 296, 298, 299, 301, 302, 304, 305, 306, 308, 310, 312, 313, 315, 316, 318, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 335, 337, 339, 342, 346, 348, 349, 350, 352, 353, 354, 355, 356, 357, 358, 362, 363, 365, 366, 368, 369, 370, 372, 375, 377, 378, 379, 380, 381, 382, 383, 384, 387, 388, 389, 390, 391, 392, 393, 394, 397, 398, 400, 402, 403, 404, 405, 406, 413, 415, 416, 417, 419, 420, 421, 424, 425, 428, 429, 430, 431, 432, 433, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 454, 455, 456, 458, 459, 460, 461, 462, 464, 465, 468, 469, 471, 472, 473, 474, 475, 476, 477, 478, 480, 481, 483, 484, 485, 486, 487, 488, 490, 491, 494, 496, 497, 498, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 513, 514, 515, or 516 of Table 1 can be measured in a patient suspected of having CLL. In additional embodiments, a patient suspected of having CLL can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 259, 269, 270, 271, 274, 278, 280, 282, 292, 296, 297, 302, 306, 330, 331, 333, 343, 347, 355, 360, 361, 371, 373, 376, 378, 390, 391, 407, 408, 423, 424, 425, 433, 434, 439, 443, 447, 448, 451, 452, 453, 458, 459, 460, 462, 463, 466, 467, 468, 469, 470, 472, 479, 482, or 489. In additional embodiments, a patient suspected of having CLL can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 282, 292, 296, 302, 306, 330, 331, 343, 355, 360, 373, 378, 390, 391, 423, 424, 425, 433, 434, 439, 443, 447, 448, 451, 452, 458, 459, 460, 462, 463, 466, 468, 469, 470, 472, 479, 482, or 489. In still further embodiments, a patient suspected of having CLL can be identified by measuring the amount of one or more of the following aberrant splice variants listed in Table 1: row 282, 296, 302, 306, 330, 331, 355, 378, 390, 391, 424, 425, 433, 439, 443, 447, 448, 451, 452, 458, 459, 460, 462, 468, 469, or 472.

In other embodiments, one or more aberrant splice variants selected from rows 2, 3, 4, 7, 9, 10, 11, 13, 16, 18, 19, 20, 21, 22, 23, 24, 27, 28, 30, 31, 32, 33, 34, 37, 38, 39, 40, 41, 42, 43, 46, 47, 49, 50, 52, 53, 54, 56, 57, 58, 61, 62, 63, 64, 66, 67, 68, 71, 72, 75, 77, 78, 79, 80, 81, 82, 84, 87, 88, 89, 90, 91, 92, 94, 95, 97, 98, 99, 100, 101, 103, 104, 106, 107, 108, 109, 110, 111, 112, 113, 114, 116, 117, 119, 120, 121, 122, 123, 124, 125, 126, 127, 131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 143, 144, 146, 147, 150, 152, 154, 155, 156, 157, 159, 163, 164, 165, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 230, 231, 232, 233, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 247, 249, 250, 251, 252, 253, 254, 255, 256, or 257 of Table 1 can be measured in a patient suspected of having breast cancer. In additional embodiments, a patient suspected of having breast cancer can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 7, 8, 9, 10, 26, 48, 66, 105, 121, 135, 136, or 166. In additional embodiments, a patient suspected of having breast cancer can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 7, 8, 9, 10, 26, 48, 66, 105, 121, 135, or 136. In still further embodiments, a patient suspected of having breast cancer can be identified by measuring the amount of one or more of the following aberrant splice variants listed in Table 1: row 7, 9, 10, 66, 121, 135, or 136.

In further embodiments, one or more aberrant splice variants selected from rows 518, 519, 520, 521, 523, 524, 525, 526, 527, 528, 529, 531, 533, 534, 536, 537, 538, 539, 543, 544, 545, 549, 551, 552, 553, 555, 556, 557, 558, 559, 560, 561, 562, 563, 565, 567, 568, 569, 570, 572, 573, 575, 577, 578, 579, 580, 581, 582, 583, 584, 585, 588, 589, 590, 591, 593, 595, 597, 598, 599, 600, 601, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 623, 625, 627, 628, 629, 630, 632, 634, 635, 636, 637, 638, 640, 641, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 654, 657, 658, 659, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 680, 682, 683, 684, 685, 686, 687, 688, 689, 690, 692, 694, 696, 697, 698, 699, 700, 701, 702, 703, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740, 741, 742, 743, 744, 745, 746, 747, 748, 750, 751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 763, 764, 765, 766, 767, 768, 770, 771, 772, 773, 774, 775, 776, 777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788, 789, or 790 of Table 1 can be measured in a patient suspected of having melanoma. In additional embodiments, a patient suspected of having melanoma can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 519, 521, 522, 535, 554, 587, 594, 601, 618, 639, 654, 655, 670, 679, 680, 727, 729, or 730. In additional embodiments, a patient suspected of having melanoma can be identified by measuring the amounts of one or more of the following aberrant splice variants listed in Table 1: row 519, 521, 522, 535, 554, 587, 601, 618, 639, 654, 670, 680, 727, or 730. In still further embodiments, a patient suspected of having melanoma can be identified by measuring the amount of one or more of the following aberrant splice variants listed in Table 1: row 519, 521, 601, 618, 654, 670, 680, 727, or 730.

In some embodiments, one or more of the aberrant variants are selected from rows 21, 31, 51, 81, 118, 279, 372, 401, 426, 443, 528, 543, 545, 548 or 566 of Table 1. In certain embodiments, a patient suspected of having cancer can be identified by measuring the amount of one or more of the aberrant variants selected from 21, 31, 51, 81, 118, 279, 372, 401, 426, 443, 528, 543, 545, 548 or 566. In various embodiments the cancer may be CLL, breast cancer, or melanoma, for example.

Additional methods include predicting or monitoring the efficacy of a treatment for cancer by measuring the level of one or more aberrant splice variants in samples obtained from patients before or during the treatment. For example, a decrease in the levels of one or more aberrant splice variants over the course of treatment may indicate that the treatment is effective. In other cases, the absence of a decrease or an increase in the levels of one or more aberrant splice variants over the course of treatment may indicate that the treatment is not effective and should be adjusted, supplemented, or terminated. In some embodiments, the splice variants are used to track and adjust individual patient treatment effectiveness.

Embodiments of the invention also encompass methods of stratifying cancer patients into different categories based on the presence or absence of one or more particular splice variants in patient samples or the detection of one or more particular splice variants at levels that are elevated or reduced relative to those in normal cell samples. Categories may be different prognostic categories, categories of patients with varying rates of recurrence, categories of patients that respond to treatment and those that do not, and categories of patients that may have particular negative side effects, and the like. According to the categories in which individual patients fall, optimal treatments may then be selected for those patients, or particular patients may be selected for clinical trials.

Embodiments also encompass methods of distinguishing cancerous cells with SF3B1 neomorphic mutations from normal cells by using the splice variants disclosed herein as markers. Such methods may be employed, for example, to assess the growth or loss of cancerous cells and to identify cancerous cells to be treated or removed. In some embodiments, the splice variants are measured in cancerous tissue having cells with a neomorphic SF3B1 mutation before and after anti-cancer treatment, for the purpose of monitoring the effect of the treatment on cancer progression.

In additional embodiments, administering an SF3B1 modulator to a cell, such as a cancer cell, can alter the differential expression of splice variants. Accordingly, the change in expression of one or more splice variants can be used to evaluate the effect of the SF3B1 modulator on the SF3B1 protein. In one embodiment, the effect of an SF3B1 modulator on a CLL cell is evaluated by applying an SF3B1 modulator to such a cell, then detecting or quantifying one or more of the splice variants in Table 1. In additional embodiments the one or more splice variants are chosen from rows 258-516 of Table 1. In further embodiments, the one or more splice variants are chosen from rows 260, 262, 263, 265, 266, 267, 272, 273, 275, 276, 277, 279, 281, 282, 286, 287, 288, 290, 294, 295, 296, 298, 299, 301, 302, 304, 305, 306, 308, 310, 312, 313, 315, 316, 318, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 335, 337, 339, 342, 346, 348, 349, 350, 352, 353, 354, 355, 356, 357, 358, 362, 363, 365, 366, 368, 369, 370, 372, 375, 377, 378, 379, 380, 381, 382, 383, 384, 387, 388, 389, 390, 391, 392, 393, 394, 397, 398, 400, 402, 403, 404, 405, 406, 413, 415, 416, 417, 419, 420, 421, 424, 425, 428, 429, 430, 431, 432, 433, 436, 437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 454, 455, 456, 458, 459, 460, 461, 462, 464, 465, 468, 469, 471, 472, 473, 474, 475, 476, 477, 478, 480, 481, 483, 484, 485, 486, 487, 488, 490, 491, 494, 496, 497, 498, 500, 501, 502, 503, 504, 505, 506, 507, 508, 509, 510, 511, 513, 514, 515, or 516 of Table 1. In further embodiments, the one or more splice variants are chosen from rows 259, 269, 270, 271, 274, 278, 280, 282, 292, 296, 297, 302, 306, 330, 331, 333, 343, 347, 355, 360, 361, 371, 373, 376, 378, 390, 391, 407, 408, 423, 424, 425, 433, 434, 439, 443, 447, 448, 451, 452, 453, 458, 459, 460, 462, 463, 466, 467, 468, 469, 470, 472, 479, 482, or 489. In additional embodiments, the one or more splice variants are chosen from rows 282, 292, 296, 302, 306, 330, 331, 343, 355, 360, 373, 378, 390, 391, 423, 424, 425, 433, 434, 439, 443, 447, 448, 451, 452, 458, 459, 460, 462, 463, 466, 468, 469, 470, 472, 479, 482, or 489 of Table 1. In still further embodiments, the one or more splice variants are chosen from rows 282, 296, 302, 306, 330, 331, 355, 378, 390, 391, 424, 425, 433, 439, 443, 447, 448, 451, 452, 458, 459, 460, 462, 468, 469, or 472 of Table 1.

In certain embodiments, the effect of an SF3B1 modulator on a breast cancer cell is evaluated by applying an SF3B1 modulator to such a cell, then detecting or quantifying one or more of the splice variants in Table 1. In additional embodiments the one or more splice variants are chosen from rows 1-257 of Table 1. In further embodiments, the one or more splice variants are chosen from rows 2, 3, 4, 7, 9, 10, 11, 13, 16, 18, 19, 20, 21, 22, 23, 24, 27, 28, 30, 31, 32, 33, 34, 37, 38, 39, 40, 41, 42, 43, 46, 47, 49, 50, 52, 53, 54, 56, 57, 58, 61, 62, 63, 64, 66, 67, 68, 71, 72, 75, 77, 78, 79, 80, 81, 82, 84, 87, 88, 89, 90, 91, 92, 94, 95, 97, 98, 99, 100, 101, 103, 104, 106, 107, 108, 109, 110, 111, 112, 113, 114, 116, 117, 119, 120, 121, 122, 123, 124, 125, 126, 127, 131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 143, 144, 146, 147, 150, 152, 154, 155, 156, 157, 159, 163, 164, 165, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 230, 231, 232, 233, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 247, 249, 250, 251, 252, 253, 254, 255, 256, or 257 of Table 1. In additional embodiments, the one or more splice variants are chosen from rows 7, 8, 9, 10, 26, 48, 66, 105, 121, 135, 136, or 166 of Table 1. In further embodiments, the one or more splice variants are chosen from rows 7, 8, 9, 10, 26, 48, 66, 105, 121, 135, or 136 of Table 1. In still further embodiments, the one or more splice variants are chosen from rows 7, 9, 10, 66, 121, 135, or 136 of Table 1.

In a further embodiment, the effect of an SF3B1 modulator on a melanoma cell is evaluated by applying an SF3B1 modulator to such a cell, then detecting or quantifying one or more of the splice variants in Table 1. In additional embodiments the one or more splice variants are chosen from rows 517-790 of Table 1. In further embodiments, the one or more splice variants are chosen from rows 518, 519, 520, 521, 523, 524, 525, 526, 527, 528, 529, 531, 533, 534, 536, 537, 538, 539, 543, 544, 545, 549, 551, 552, 553, 555, 556, 557, 558, 559, 560, 561, 562, 563, 565, 567, 568, 569, 570, 572, 573, 575, 577, 578, 579, 580, 581, 582, 583, 584, 585, 588, 589, 590, 591, 593, 595, 597, 598, 599, 600, 601, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 623, 625, 627, 628, 629, 630, 632, 634, 635, 636, 637, 638, 640, 641, 643, 644, 645, 646, 647, 648, 649, 650, 651, 652, 654, 657, 658, 659, 661, 662, 663, 664, 665, 666, 667, 668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678, 680, 682, 683, 684, 685, 686, 687, 688, 689, 690, 692, 694, 696, 697, 698, 699, 700, 701, 702, 703, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740, 741, 742, 743, 744, 745, 746, 747, 748, 750, 751, 752, 753, 754, 755, 756, 757, 758, 759, 760, 763, 764, 765, 766, 767, 768, 770, 771, 772, 773, 774, 775, 776, 777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788, 789, or 790 of Table 1. In still further embodiments, the one or more splice variants are chosen from rows 519, 521, 522, 535, 554, 587, 594, 601, 618, 639, 654, 655, 670, 679, 680, 727, 729, or 730 of Table 1. In additional embodiments, the one or more splice variants are chosen from rows 519, 521, 522, 535, 554, 587, 601, 618, 639, 654, 670, 680, 727, or 730 of Table 1. In still further embodiments, the one or more splice variants are chosen from rows 519, 521, 601, 618, 654, 670, 680, 727, or 730 of Table 1.

In some embodiments, the effect of an SF3B1 modulator on a cancer cell is evaluated by applying an SF3B1 modulator to such a cell, then detecting or quantifying one or more of the aberrant variants selected from rows 21, 31, 51, 81, 118, 279, 372, 401, 426, 443, 528, 543, 545, 548 or 566 of Table 1. In various embodiments, the cancer cell may be a CLL cell, a breast cancer cell, or a melanoma cell, for example.

The specific splice variants that are useful for demonstrating the effect of an SF3B1 modulator on one type of cancer cell may not be useful for demonstrating an effect of the modulator on another type of cancer cell. Aberrant splice variants that are appropriate for revealing such effects in particular cancer cells will be apparent from the description and examples provided herein.

In some embodiments, aberrant splice variants that are present at elevated levels in a cell having a neomorphic SF3B1 protein are used as markers. In other embodiments, splice variants that have reduced levels in a cell having a neomorphic SF3B1 protein are used as markers. In some embodiments, more than one splice variant will be measured. When more than one splice variant is used, they may all have elevated levels, all have reduced levels, or a mixture of splice variants with elevated and reduced levels may be used. In certain embodiments of the methods described herein, more than one aberrant splice variant is measured. In other embodiments, at least one aberrant and at least one canonical splice variant is measured. In some cases, both an aberrant and canonical splice variant associated with a particular genomic location will be measured. In other circumstances, a measured canonical splice variant will be at a different genomic location from the measured aberrant splice variant(s).

Before performing an assay for splice variants in a cell, one may determine whether the cell has a mutant SF3B1 protein. In certain embodiments, the assay for splice variants is performed if the cell has been determined to have a neomorphic SF3B1 mutant protein.

Samples

Cell samples can be obtained from a variety of biological sources. Exemplary cell samples include but are not limited to a cell culture, a cell line, a tissue, oral tissue, gastrointestinal tissue, an organ, an organelle, a biological fluid, a blood sample, a urine sample, a skin sample, and the like. Blood samples may be whole blood, partially purified blood, or a fraction of whole or partially purified blood, such as peripheral blood mononucleated cells (PBMCs). The source of a cell sample may be a solid tissue sample such as a tissue biopsy. Tissue biopsy samples may be biopsies from breast tissue, skin, lung, or lymph nodes. Samples may be samples of bone marrow, including bone marrow aspirates and bone marrow biopsies.

In certain embodiments, the cells are human cells. Cells may be cancer cells, for example hematological cancer cells or solid tumor cells. Hematological cancers include chronic lymphocytic leukemia, acute lymphoblastic leukemia, acute myeloid leukemia, chronic myeloid leukemia, chronic myelomonocytic leukemia, acute monocytic leukemia, Hodgkin's lymphoma, Non-Hodgkin's lymphoma, and multiple myeloma. Solid tumors include carcinomas, such as adenocarcinomas, and may be selected from breast, lung, liver, prostate, pancreatic, colon, colorectal, skin, ovarian, uterine, cervical, or renal cancers. Cell samples may be obtained directly from a patient or derived from cells obtained from a patient, such as cultured cells derived from a biological fluid or tissue sample. Samples may be archived samples, such as kryopreserved samples, of cells obtained directly from a subject or of cells derived from cells obtained from a patient.

In certain embodiments, cells are obtained from patients suspected of having cancer. The patients may show signs and symptoms of cancer, such as one or more common symptoms of CLL, which include enlarged lymph nodes, liver, or spleen, higher-than-normal white blood cell counts, recurring infections, loss of appetite or early satiety, abnormal bruising, fatigue, and night sweats. In additional embodiments, the cells have a mutant SF3B1 protein.

Cell samples described herein may be used in any of the methods presently disclosed.

Detection of Splice Variants

Certain embodiments of the methods described herein involve detection or quantification of splice variants. A variety of methods exists for detecting and quantifying nucleic acids, and each may be adapted for detection of splice variants in the described embodiments. Exemplary methods include an assay to quantify nucleic acid such as nucleic acid barcoding, nanoparticle probes, in situ hybridization, microarray, nucleic acid sequencing, and PCR-based methods, including real-time PCR (RT-PCR).

Nucleic acid assays utilizing barcoding technology such as NanoString® assays (NanoString Technologies) may be performed, for example, as described in U.S. Pat. Nos. 8,519,115; 7,919,237; and in Kulkarni, M. M., 2011, “Digital Multiplexed Gene Expression Analysis Using the NanoString nCounter System.” Current Protocols in Molecular Biology, 94:25B.10.1-25B.10.17. In an exemplary assay, a pair of probes is used to detect a particular nucleotide sequence of interest, such as a particular splice variant of interest. The probe pair consists of a capture probe and a reporter probe and that each include a sequence of from about 35 to 50 bases in length that is specific for a target sequence. The capture probe includes an affinity label such as biotin at its 3′ end that provides a molecular handle for surface-attachment of target mRNAs for digital detection, and the reporter probe includes a unique color code at its 5′ end that provides molecular barcoding of the hybridized mRNA target sequence. Capture and reporter probe pairs are hybridized to target mRNA in solution, and after excess probes are removed, the target mRNA-probe complexes are immobilized in an nCounter® cartridge. A digital analyzer acquires direct images of the surface of the cartridge to detect color codes corresponding to specific mRNA splice variant sequences. The number of times a color-coded barcode for a particular splice variant is detected reflects the levels of a particular splice variant in the mRNA library. For the detection of splice variants, either the capture or the reporter probe may span a given splice variant's exon-exon or intron-exon junction. In other embodiments, one or both of the capture and reporter probes' target sequences correspond to the terminal sequences of two exons at an exon-exon junction or to the terminal sequences of an intron and an exon at an intron-exon junction, whereby one probe extends to the exon-exon or intron-exon junction, but does not span the junction, and the other probe binds a sequence that begins on opposite side of the junction and extends into the respective exon or intron.

In exemplary PCR-based methods, a particular splice variant may be detected by specifically amplifying a sequence that contains the splice variant. For example, the method may employ a first primer specifically designed to hybridize to a first portion of the splice variant, where the splice variant is a sequence that spans an exon-exon or intron-exon junction at which alternative splicing occurs. The method may further employ a second opposing primer that hybridizes to a segment of the PCR extension product of the first primer that corresponds to another sequence in the gene, such as a sequence at an upstream or downstream location. The PCR detection method may be quantitative (or real-time) PCR. In some embodiments of quantitative PCR, an amplified PCR product is detected using a nucleic acid probe, wherein the probe may contain one or more detectable labels. In certain quantitative PCR methods, the amount of a splice variant of interest is determined by detecting and comparing levels of the splice variant to an appropriate internal control.

Exemplary methods for detecting splice variants using an in situ hybridization assay such as RNAscope® (Advanced Cell Diagnostics) include those described by Wang, F., et al., “RNAscope: a novel in situ RNA analysis platform for formalin-fixed, paraffin-embedded tissues,” J. Mol. Diagn. 2012 January; 14(1):22-9. RNAscope® assays may be used to detect splice variants by designing a pair of probes that targets a given splice variant, and are hybridized to target RNA in fixed and permeabilized cells. Target probes are designed to hybridize as pairs which, when hybridized to the target sequence, create a binding site for a preamplifier nucleic acid. The preamplifier nucleic acid, in turn, harbors multiple binding sites for amplifier nucleic acids, which in turn contain multiple binding sites for a labeled probe carrying a chromogenic or fluorescent molecule. In some embodiments, one of the RNAscope® target probes spans a given splice variant's exon-exon or intron-exon junction. In other embodiments, the target probes' target sequences correspond to the terminal sequences of two exons at an exon-exon junction or to the terminal sequences of an intron and an exon at an intron-exon junction, whereby one probe in the target probe pair extends to the exon-exon or intron-exon junction, but does not span the junction, and the other probe binds a sequence beginning on opposite side of the junction and extending into the respective exon or intron.

Exemplary methods for detecting splice variants using nanoparticle probes such as SmartFlare™ (Millipore) include those described in Seferos et al., “Nano-flares: Probes for Transfection and mRNA Detection in Living Cells,” J. Am. Chem. Soc. 129(50):15477-15479 (2007) and Prigodich, A. E., et al., “Multiplexed Nanoflares: mRNA Detection in Live Cells,” Anal. Chem. 84(4):2062-2066 (2012). SmartFlare™ detection probes may be used to detect splice variants by generating gold nanoparticles that are modified with one or more nucleic acids that include nucleotide recognition sequences that (1) are each complementary to a particular splice variant to be detected and (2) are each hybridized to a complementary fluorophore-labeled reporter nucleic acid. Upon uptake of the probe by a cell, a target splice variant sequence may hybridize to the one or more nucleotide recognition sequences and displace the fluorophore-labeled reporter nucleic acid. The fluorophore-labeled reporter nucleic acid, whose fluorophore had been quenched due to proximity to the gold nanoparticle surface, is then liberated from the gold nanoparticle, and the fluorophore may then be detected when free of the quenching effect of the nanoparticle. In some embodiments, nucleotide recognition sequences in the probes recognize a sequence that spans a given splice variant's exon-exon or intron-exon junction. In some embodiments, nucleotide recognition sequences in the probes recognize a sequence that is only on one side of the splice variant's exon-exon or intron-exon junction, including a sequence that terminates at the junction and a sequence that terminates one or more nucleotides away from the junction.

Exemplary methods for detecting splice variants using nucleic acid sequencing include RNA sequencing (RNA-Seq) described in Ren, S. et al. “RNA-Seq analysis of prostate cancer in the Chinese population identifies recurrent gene fusions, cancer-associated long noncoding RNAs and aberrant alternative splicings.” Cell Res 22, 806-821, doi:10.1038/cr.2012.30 (2012); and van Dijk et al., “Ten years of next-generation sequencing technology.” Trends Genet 30(9):418-26 (2014). In some embodiments, high-throughput sequencing, such as next-generation sequencing (NGS) technologies, may be used to detected splice variants. For example, the method may employ commercial sequencing platforms available for RNA-Seq, such as, e.g., Illumina, SOLID, Ion Torrent, and Roche 454. In some embodiments, the sequencing method may include pyrosequencing. For example, a sample may be mixed with sequencing enzymes and primer and exposed to a flow of one unlabeled nucleotide at a time, allowing synthesis of the complementary DNA strand. When a nucleotide is incorporated, pyrophosphate is released leading to light emission, which is monitored in real time. In some embodiments, the sequencing method may include semiconductor sequencing. For example, proton instead of pyrophosphate may be released during nucleotide incorporation and detected in real time by ion sensors. In some embodiments, the method may include sequencing with reversible terminators. For example, the synthesis reagents may include primers, DNA polymerase, and four differently labelled, reversible terminator nucleotides. After incorporation of a nucleotide, which is identified by its color, the 3′ terminator on the base and the fluorophore are removed, and the cycle is repeated. In some embodiments, the method may include sequencing by ligation. For example, a sequencing primer may be hybridized to an adapter, with the 5′ end of the primer available for ligation to an oligonucleotide hybridizing to the adjacent sequence. A mixture of octamers, in which bases 4 and 5 are encoded by one of four color labels, may compete for ligation to the primer. After color detection, the ligated octamer may be cleaved between position 5 and 6 to remove the label, and the cycle may be repeated. Thereby, in the first round, the process may determine possible identities of bases in positions 4, 5, 9, 10, 14, 15, etc. The process may be repeated, offset by one base using a shorter sequencing primer, to determine positions 3, 4, 8, 9, 13, 14, etc., until the first base in the sequencing primer is reached.

Other nucleic acid detection and analytical methods that also distinguish between splice variants of a given exon-exon or intron-exon junction in a gene by identifying the nucleotide sequence on both sides of the junction may be utilized to detect or quantify the splice variants disclosed herein. For example, splice variants of an exon-exon junction may be detected by primer extension methods in which a primer that binds to one exon is extended into the exon on the other side of the junction according to the sequence of that adjacent exon. See, for example, McCullough, R. M., et al., “High-throughput alternative splicing quantification by primer extension and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,” Nucleic Acids Research, 2005 Jun. 20; 33(11):e99; and Milani, L., et al., “Detection of alternatively spliced transcripts in leukemia cell lines by minisequencing on microarrays,” Clin. Chem. 52: 202-211 (2006). Detection of variants on a large scale may be performed using expression microarrays that carry exon-exon or intron-exon junction probes, as described, for example, in Johnson, J. M. et al., “Genome-wide survey of human alternative pre-mRNA splicing with exon junction microarrays,” Science 302: 2141-2144 (2003); and Modrek, B., et al., “Genome-wide detection of alternative splicing in expressed sequences of human genes,” Nucleic Acids Res 29: 2850-2859 (2001).

Various embodiments include reagents for detecting splice variants of the invention. In one example, reagents include NanoString® probes designed to measure the amount of one or more of the aberrant splice variants listed in Table 1. Probes for nucleic acid quantification assays such as barcoding (e.g. NanoString®), nanoparticle probes (e.g. SmartFlare™), in situ hybridization (e.g. RNAscope®), microarray, nucleic acid sequencing, and PCR-based assays may be designed as set forth above.

In these exemplary methods or in other methods for nucleic acid detection, aberrant splice variants may be identified using probes, primers, or other reagents which specifically recognize the nucleic acid sequence that is present in the aberrant splice variant but absent in the canonical splice variant. In other embodiments, the aberrant splice variant is identified by detecting the sequence that is specific to the aberrant splice variant in the context of the junction in which it occurs, i.e., the unique sequence is flanked by the sequences which are present on either side of the splice junction in the canonical splice variant. In such cases, the portion of the probe, primer, or other detection reagent that specifically recognizes its target sequence may have a length that corresponds to the length of the aberrant sequence or to or a portion of the aberrant sequence. In other embodiments, the portion of the probe, primer, or other detection reagent that specifically recognizes its target sequence may have a length that corresponds to the length of the aberrant sequence plus the length of a chosen number of nucleotides from one or both of the sequences which flank the aberrant sequence at the splice junction. Generally, the probe or primer should be designed with a sufficient length to reduce non-specific binding. Probes, primers, and other reagents that detect aberrant or canonical splice variants may be designed according to the technical features and formats of a variety of methods for detection of nucleic acids.

SF3B1 Modulators

A variety of SF3B1 modulating compounds are known in the art, and can be used in accordance with the methods described herein. In some embodiments, the SF3B1 modulating compound is a pladienolide or pladienolide analog. A “pladienolid analog” refers to a compound which is structurally related to a member of the family of natural products known as the pladienolides. Plandienolides were first identified in the bacteria Streptomyces platensis (Sakai, Takashi; Sameshima, Tomohiro; Matsufuji, Motoko; Kawamura, Naoto; Dobashi, Kazuyuki; Mizui, Yoshiharu. “Pladienolides, New Substances from Culture of Streptomyces platensis Mer-11107. I. Taxonomy, Fermentation, Isolation and Screening.” The Journal of Antibiotics. 2004, Vol. 57, No. 3). One of these compounds, pladienolide B, targets the SF3B spliceosome to inhibit splicing and alter the pattern of gene expression (Kotake et al., “Splicing factor SF3b as a target of the antitumor natural product pladienolide”, Nature Chemical Biology 3:570-575 [2007]). Certain pladienolide B analogs are described in WO 2002/060890; WO 2004/011459; WO 2004/011661; WO 2004/050890; WO 2005/052152; WO 2006/009276; and WO 2008/126918.

U.S. Pat. Nos. 7,884,128 and 7,816,401, both entitled “Process for Total Synthesis of Pladienolide B and Pladienolide D,” describe methods for synthesizing pladienolide B and D. Synthesis of pladienolide B and D may also be performed using methods described in Kanada et al., “Total Synthesis of the Potent Antitumor Macrolides Pladienolide B and D,” Angew. Chem. Int. Ed. 46:4350-4355 (2007). Kanada et al., U.S. Pat. No. 7,550,503, and International Publication No. WO 2003/099813 (WO '813), entitled “Novel Physiologically Active Substances,” describe methods for synthesizing E7107 (Compound 45 of WO '813) from pladienolide D (11107D of WO '813). In some embodiments, the SF3B1 modulator is pladienolide B. In other embodiments, the SF3B1 modulator is pladienolide D. In further embodiments, the SF3B1 modulator is E7107.

In some embodiments, the SF3B1 modulator is a compound described in U.S. application Ser. No. 14/710,687, filed May 13, 2015, which is incorporated herein by reference in its entirety. In some embodiments, the SF3B1 modulating compound is a compound having one of formulas 1-4 as set forth in Table 2. Table 2. Exemplary SF3B1 modulating compounds.

Compound Structure

1

2

3

4

The methods described herein may be used to evaluate known and novel SF3B1 modulating compounds.

Methods of Treatment

Various embodiments of the invention include treating a patient diagnosed with cancer using an SF3B1 modulator. In certain instances, cancer cells from the patient have been determined to have a mutant SF3B1 protein. Specific SF3B1 mutants include E622D, E622K, E622Q, E622V, Y623C, Y623H, Y623S, R625C, R625G, R625H, R625L, R625P, R625S, N626D, N626H, N626I, N626S, N626Y, H662D, H662L, H662Q, H662R, H662Y, T663I, T663P, K666E, K666M, K666N, K666Q, K666R, K666S, K666T, K700E, V701A, V701F, V701I, I704F, I704N, I704S, I704V, G740E, G740K, G740R, G740V, K741N, K741Q, K741T, G742D, D781E, D781G, or D781N. In certain embodiments, SF3B1 mutants are chosen from K700E, K666N, R625C, G742D, R625H, E622D, H662Q, K666T, K666E, K666R, G740E, Y623C, T663I, K741N, N626Y, T663P, H662R, G740V, D781E, or R625L. In additional embodiments, the cancer cells have been tested to measure the amount of one or more splice variants selected from Table 1. Specific splice variants associated with neomorphic SF3B1 mutations are shown in Table 1 and described in the section on splice variants above.

In certain embodiments, a cancer patient determined to have a mutant SF3B1 protein is treated with an SF3B1 modulator as described in U.S. application Ser. No. 14/710,687, filed May 13, 2015.