ER+ luminal tumors are the most frequent subtype of breast cancer. Stat1−/− mice develop mammary tumors that closely resemble this cancer subtype. To identify transforming events that contribute to tumorigenesis, we performed whole genome sequencing of Stat1−/− primary mammary tumors and matched normal tissues. This investigation identified somatic truncating mutations affecting the prolactin receptor (Prlr) in all tumor samples. Targeted sequencing confirmed the presence of these mutations in precancerous lesions, indicating this is an early event in tumorigenesis. Functional evaluation showed that co-expression of truncated and wild type Prlr led to aberrant Stat3 and Stat5 activation downstream of the receptor, cellular transformation in vitro and tumor formation in vivo.
Obi Griffith, Malachi Griffith, Kilannin Krysiak, Zachary Skidmore, Jasreet Hundal, Lee Trani
We reported the first comprehensive genomic analysis of a case of Mixed fibrolamellar hepatocellular carcinoma (mFL-HCC). No common HCC-associated mutations were identified. The very low mutation rate of this case, large number of mostly single-copy, long-range copy number variants, and high expression of ERBB2 were more consistent with previous reports of pure FL-HCC than conventional HCC. In particular, the DNAJB1:PRKACA fusion transcript specifically associated with pure FL-HCC was detected at very high expression levels. Subsequent analysis revealed the presence of this fusion in all primary and metastatic samples, including those with mixed or conventional HCC pathology. A second case of mFL-HCC confirmed our finding that the fusion was detectable in conventional components. An expanded screen identified a third case of fusion-positive HCC, which upon review, also had both conventional and fibrolamellar features. This screen confirmed the absence of the fusion in all conventional HCC and adjacent non-tumor liver samples. These results indicate that mFL-HCC is similar to pure FL-HCC at the genomic level and the DNAJB1:PRKACA fusion can be used as a diagnostic tool for both pure and mFL-HCC.
Obi Griffith, Malachi Griffith, Kilannin Krysiak, Avinash Ramu, Zachary Skidmore, Jason Kunisaki
Nearly all patients with small cell lung cancer (SCLC) eventually relapse with chemotherapy resistant disease. The molecular mechanisms driving chemotherapy resistance in SCLC remain to be characterized. We performed whole-exome sequencing of paired SCLC tumor samples procured at diagnosis (treatment-naive samples) and relapse (relapse samples) from 12 patients, along with unpaired relapse samples obtained from 18 additional patients. We observed multiple somatic copy number alterations including gains in ABCC1, and deletions in MYCL, MSH2, and MSH6 among relapse samples. Relapse samples also showed recurrent mutations in regulators of WNT signaling such as CHD8 and APC. Analysis of RNA-sequencing data suggested an enrichment for “ASCL1-low” expression subtype and WNT activation in relapse samples. Activation of WNT signaling in chemotherapy sensitive human SCLC cell lines through APC knockdown induced chemotherapy resistance. Additionally, in vitro-derived chemotherapy resistant cell lines demonstrated increased WNT activity. Our results support a role for WNT signaling activation as a mechanism of chemotherapy resistance in relapsed SCLC.
Wagner, Devarakonda et al. 2018. Nature Communications. In Press.
Alex Wagner, Zach Skidmore, Kilannin Krysiak, Avinash Ramu, Lee Trani, Jason Kunisaki, Nick Spies
Follicular lymphoma (FL) is the most common form of indolent non-Hodgkin lymphoma, yet it remains only partially characterized at the genomic level. To improve our understanding of the genetic underpinnings of this incurable and clinically heterogeneous disease, whole-exome sequencing was performed on tumor/normal pairs from a discovery cohort of 24 patients with FL. Using these data and mutations identified in other B-cell malignancies, 1716 genes were sequenced in 113 FL tumor samples from 105 primarily treatment-naive individuals. We identified 39 genes that were mutated significantly above background mutation rates. CREBBP mutations were associated with inferior PFS. In contrast, mutations in previously unreported HVCN1, a voltage-gated proton channel-encoding gene and B-cell receptor signaling modulator, were associated with improved PFS. In total, 47 (44.8%) patients harbor mutations in the interconnected B-cell receptor (BCR) and CXCR4 signaling pathways. Histone gene mutations were more frequent than previously reported (identified in 43.8% of patients) and often co-occurred (17.1% of patients). A novel, recurrent hotspot was identified at a posttranslationally modified residue in the histone H2B family. This study expands the number of mutated genes described in several known signaling pathways and complexes involved in lymphoma pathogenesis (BCR, Notch, SWitch/sucrose nonfermentable (SWI/SNF), vacuolar ATPases) and identified novel recurrent mutations (EGR1/2, POU2AF1, BTK, ZNF608, HVCN1) that require further investigation in the context of FL biology, prognosis, and treatment.
Kilannin Krysiak, Felicia Gomez, Matthew Matlock, Lee Trani, Malachi Griffith, Obi Griffith
Comprehensive genomic analysis was performed on patient derived xenografts for oral squamous cell carcinomas (OSCC). We found PDX samples were largely correlative with the primary tumors from which they were derived. PDX models were able to retain the heterogeneous mutational landscape and clonal architecture of tumors. Somatic differences between the PDX and corresponding OSCC primary samples consisted primarily of low-frequency mutations, making these xenografts ideal models for exploring OSCC tumor biology.
Campbell, Lin, Zolkind et al. 2018. Cell Reports. In Press.
Katie Campbell, Zachary Skidmore, Erica Barnell, Malachi Griffith, Obi Griffith
In support of several clinical trials we are creating and applying new immunogenomics tools to help predict response to checkpoint blockade inhibition therapies and design personalized cancer vaccines.
Jasreet Hundal, Katie Campbell, Yang-Yang Feng, Connor Liu, Joshua McMichael, Susanna Kiwala, Obi Griffith, Malachi Griffith
CIViC is an expert-crowdsourced knowledgebase for Clinical Interpretation of Variants in Cancer describing the therapeutic, prognostic, diagnostic and predisposing relevance of inherited and somatic variants of all types. CIViC is committed to open-source code, open-access content, public application programming interfaces (APIs) and provenance of supporting evidence to allow for the transparent creation of current and accurate variant interpretations for use in cancer precision medicine.
Malachi Griffith, Nicholas Spies, Kilannin Krysiak, Josh McMichael, Adam Coffman, Arpad Danos, Benjamin Ainscough, Cody Ramirez, Lynzey Kujan, Erica Barnell, Alex Wagner, Zachary Skidmore, Connor Liu, Rachel Bilski, Robert Lesurf, Yang Yang Feng, Lee Trani, Matt Matlock, Avinash Ramu, Katie Campbell, Greg Spies, Aaron Graubert, Jason Walker, Obi Griffith
Extensive genomic analyses were performed in an adult with post-allo relapsed B-ALL. Mutations were found in EP300, NF1, IKZF1, SETD2, RB1, PAX5, NF1, ETV6, and ZNF384. Transcriptome analysis identified aberrant overexpression of the FLT3 gene. Treatment with the FLT3 inhibitor sunitinib induced a rapid clinical and molecular response. This study demonstrates a powerful proof-of-principle that comprehensive genomic studies can sometimes reveal unexpected clinically actionable therapeutic targets.
Malachi Griffith, Obi Griffith, Kilannin Krysiak, Zachary Skidmore, Avinash Ramu, Alex Wagner, Katie Campbell, Robert Lesurf, Jasreet Hundal, Nicholas Spies, Benjamin Ainscough, Jason Walker
Tumors are typically sequenced to depths of 75-100× (exome) or 30-50× (whole genome). We demonstrated that current sequencing paradigms are inadequate for tumors that are impure, aneuploid or clonally heterogeneous. To reassess optimal sequencing strategies, we performed ultra-deep (up to ~312×) whole genome sequencing (WGS) and exome capture (up to ~433×) of a primary acute myeloid leukemia, its subsequent relapse, and a matched normal skin sample. We tested multiple alignment and variant calling algorithms and validated ~200,000 putative SNVs by sequencing them to depths of ~1,000×. Additional targeted sequencing provided over 10,000× coverage and ddPCR assays provided up to ~250,000× sampling of selected sites. We evaluated the effects of different library generation approaches, depth of sequencing, and analysis strategies on the ability to effectively characterize a complex tumor. This dataset, representing the most comprehensively sequenced tumor described to date, serves as an invaluable community resource.
Malachi Griffith, Obi Griffith, Kilannin Krysiak, Zach Skidmore, Avinash Ramu, Jason Walker, Lee Trani