Sanchez-Vega F, Mina M, Armenia J, Chatila WK, Luna A, La KC, Dimitriadoy S, Liu DL, Kantheti HS, Saghafinia S, Chakravarty D, Daian F, Gao Q, Bailey MH, Liang WW, Foltz SM, Shmulevich I, Ding L, Heins Z, Ochoa A, Gross B, Gao J, Zhang H, Kundra R, Kandoth C, Bahceci I, Dervishi L, Dogrusoz U, Zhou W, Shen H, Laird PW, Way GP, Greene CS, Liang H, Xiao Y, Wang C, Iavarone A, Berger AH, Bivona TG, Lazar AJ, Hammer GD, Giordano T, Kwong LN, McArthur G, Huang C, Tward AD, Frederick MJ, McCormick F, Meyerson M; Cancer Genome Atlas Research Network, Van Allen EM, Cherniack AD, Ciriello G, Sander C, Schultz N.

Abstract
Genetic alterations in signaling pathways that control cell-cycle progression, apoptosis, and cell growth are common hallmarks of cancer, but the extent, mechanisms, and co-occurrence of alterations in these pathways differ between individual tumors and tumor types. Using mutations, copy-number changes, mRNA expression, gene fusions and DNA methylation in 9,125 tumors profiled by The Cancer Genome Atlas (TCGA), we analyzed the mechanisms and patterns of somatic alterations in ten canonical pathways: cell cycle, Hippo, Myc, Notch, Nrf2, PI-3-Kinase/Akt, RTK-RAS, TGFβ signaling, p53 and β-catenin/Wnt. We charted the detailed landscape of pathway alterations in 33 cancer types, stratified into 64 subtypes, and identified patterns of co-occurrence and mutual exclusivity. Eighty-nine percent of tumors had at least one driver alteration in these pathways, and 57% percent of tumors had at least one alteration potentially targetable by currently available drugs. Thirty percent of tumors had multiple targetable alterations, indicating opportunities for combination therapy.

Cell. 2018 Apr 5;173(2):321-337

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Blakely C, Watkins TBK, Wu W, Gini B, Chabon J, McCoach C, McGranahan N, Wilson GA, Birkbak NJ, Olivas V, Rotow J, Maynard A, Wang V, Gubens M, Banks K, Lanman R, Caulin A, St. John J, Cordero A, Giannikopoulos P, Mack P, Gandara D, Husain H, Doebele R, Riess J, Diehn M, Swanton C, Bivona TG.

Abstract

A widespread approach to modern cancer therapy is to identify a single oncogenic driver gene and target its mutant protein product (e.g. EGFR inhibitor treatment in EGFR-mutant lung cancers). However, genetically-driven resistance to targeted therapy limits patient survival. Through genomic analysis of 1122 EGFR-mutant lung cancer cell-free DNA samples and whole exome analysis of seven longitudinally collected tumor samples from an EGFR-mutant lung cancer patient, we identify critical co-occurring oncogenic events present in most advanced-stage EGFR-mutant lung cancers. We define new pathways limiting EGFR inhibitor response, including WNT/β-catenin and cell cycle gene (e.g. CDK4, CDK6) alterations. Tumor genomic complexity increases with EGFR inhibitor treatment and co-occurring alterations in CTNNB1, and PIK3CA exhibit non-redundant functions that cooperatively promote tumor metastasis or limit EGFR inhibitor response. This study challenges the prevailing single-gene driver oncogene view and links clinical outcomes to co-occurring genetic alterations in advanced-stage EGFR-mutant lung cancer patients.

Nature Genetetics. 2017 Dec; 49(12)

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Nichols RJ, Haderk F, Stahlhut C, Schulze CJ, Hemmati G, Wildes D, Tzitzilonis C, Mordec K, Marquez A, Romero J, Hsieh D, Kiss G, Koltun ES, Gill AL, Singh M, Goldsmith MA, Smith JAM, Bivona TG.

Abstract
Oncogenic alterations in the RAS-RAF-MEK-ERK pathway, including mutant forms of KRAS, BRAF, and loss of the tumor suppressor and RAS GTPase-activating protein (GAP) NF1, drive the growth of a wide spectrum of human cancers. While BRAF and MEK inhibitors are effective in many patients with oncogenic BRAF V600E, there are no effective targeted therapies for individuals with cancers driven by other pathway alterations, including oncogenic KRAS, non-V600E BRAF, and NF1 loss. Here, we show that targeting the PTPN11/SHP2 phosphatase with a novel small molecule allosteric inhibitor is effective against cancers bearing nucleotide-cycling oncogenic RAS (e.g. KRAS G12C), RAS-GTP dependent oncogenic BRAF (e.g. class 3 BRAF mutants), or NF1 loss in multiple preclinical models in vitro and in vivo. SHP2 inhibition suppressed the levels of RAS-GTP and phosphorylated ERK in these models and induced growth inhibition. Expression of a constitutively active mutant of the RAS guanine nucleotide exchange factor (GEF) SOS1 rescued cells from the effects of SHP2 inhibition, suggesting that SHP2 blockade decreases oncogenic RAS-RAF-MEK-ERK signaling by disrupting SOS1-mediated RAS-GTP loading. Our findings illuminate a critical function for SHP2 in promoting oncogenic RAS activation and downstream signaling in cancers with nucleotide-cycling oncogenic RAS, RAS-GTP dependent oncogenic BRAF, and NF1 loss. SHP2 inhibition thus represents a rational, biomarker-driven therapeutic strategy to be tested in patients with cancers of diverse origins bearing these oncogenic drivers and for which current treatments are largely ineffective.

bioRxiv 188730: September 14, 2017

Okimoto RA, Breitenbuecher F, Olivas VO, Wei W, Gini B, Hofree M, Asthana S, Hrustanovic G, Flanagan J, Tulpule A, Blakely CM, Haringsma HJ, Simmons AD, Gowen K, Suh J, Miller VA, Ali S, Schuler M, Bivona TG.

Abstract
Metastasis is the leading cause of death in lung cancer patients, yet the molecular effectors underlying tumor dissemination remain poorly defined. Through development of an in vivo spontaneous lung cancer metastasis model, we show that the developmentally-regulated transcriptional repressor Capicua (CIC) suppresses invasion and metastasis. CIC inactivation relieves repression of its effector ETV4, driving ETV4-mediated upregulation of MMP24 that is necessary and sufficient for metastasis. Loss of CIC, or increased levels of its effectors ETV4 and MMP24, is a biomarker of tumor progression and worse outcomes in lung and gastric cancer patients. Our findings uncover CIC as a conserved metastasis suppressor, revealing new anti-metastatic strategies to improve patient outcomes.

Nature Genetics 2017 Jan;49(1):87-96

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Okimoto RA, Lin L, Olivas V, Chan E, Markegard E, Rymar A, Neel D, Chen X, Hemmati G, Bollag G, Bivona TG.

Abstract
Oncogenic activation of protein kinase BRAF drives tumor growth by promoting mitogen-activated protein kinase (MAPK) pathway signaling. Because oncogenic mutations in BRAF occur in ∼2–7% of lung adenocarcinoma (LA), BRAF-mutant LA is the most frequent cause of BRAF-mutant cancer mortality worldwide. Whereas most tumor types harbor predominantly the BRAFV600E-mutant allele, the spectrum of BRAF mutations in LA includes BRAFV600E (∼60% of cases) and non-V600E mutant alleles (∼40% of cases) such as BRAFG469A and BRAFG466V. The presence of BRAFV600E in LA has prompted clinical trials testing selective BRAF inhibitors such as vemurafenib in BRAFV600E-mutant patients. Despite promising clinical efficacy, both innate and acquired resistance often result from reactivation of MAPK pathway signaling, thus limiting durable responses to the current BRAF inhibitors. Further, the optimal therapeutic strategy to block non-V600E BRAF-mutant LA remains unclear. Here, we report the efficacy of the Raf proto-oncogene serine/threonine protein kinase (RAF) inhibitor, PLX8394, that evades MAPK pathway reactivation in BRAF-mutant LA models. We show that PLX8394 treatment is effective in both BRAFV600E and certain non-V600 LA models, in vitro and in vivo. PLX8394 was effective against treatment-naive BRAF-mutant LAs and those with acquired vemurafenib resistance caused by an alternatively spliced, truncated BRAFV600E that promotes vemurafenib-insensitive MAPK pathway signaling. We further show that acquired PLX8394 resistance occurs via EGFR-mediated RAS-mTOR signaling and is prevented by upfront combination therapy with PLX8394 and either an EGFR or mTOR inhibitor. Our study provides a biological rationale and potential polytherapy strategy to aid the deployment of PLX8394 in lung cancer patients.

Proc Natl Acad Sci U S A. 2016 Nov 22

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Sabnis AJ, Guerriero CG, Olivas V, Sayana A, Shue J, Flanagan J, Asthana S, Paton A, Paton J, Gestwicki J, Walter P, Weissman J, Wipf P, Brodsky J, Bivona TG.

Abstract
Cytosolic and organelle-based heat-shock protein (HSP) chaperones ensure proper folding and function of nascent and injured polypeptides to support cell growth. Under conditions of cellular stress, including oncogenic transformation, proteostasis components maintain homeostasis and prevent apoptosis. Although this cancer-relevant function has provided a rationale for therapeutically targeting proteostasis regulators (e.g., HSP90), cancer-subtype dependencies upon particular proteostasis components are relatively undefined. Here, we show that human rhabdomyosarcoma (RMS) cells, but not several other cancer cell types, depend upon heat-shock protein 70 kDA (HSP70) for survival. HSP70-targeted therapy (but not chemotherapeutic agents) promoted apoptosis in RMS cells by triggering an unfolded protein response (UPR) that induced PRKR-like endoplasmic reticulum kinase (PERK)–eukaryotic translation initiation factor α (eIF2α)–CEBP homologous protein (CHOP) signaling and CHOP-mediated cell death. Intriguingly, inhibition of only cytosolic HSP70 induced the UPR, suggesting that the essential activity of HSP70 in RMS cells lies at the endoplasmic reticulum–cytosol interface. We also found that increased CHOP mRNA in clinical specimens was a biomarker for poor outcomes in chemotherapy-treated RMS patients. The data suggest that, like human epidermal growth factor receptor 2 (HER2) amplification in breast cancer, increased CHOP in RMS is a biomarker of decreased response to chemotherapy but enhanced response to targeted therapy. Our findings identify the cytosolic HSP70–UPR axis as an unexpected regulator of RMS pathogenesis, revealing HSP70-targeted therapy as a promising strategy to engage CHOP-mediated apoptosis and improve RMS treatment. Our study highlights the utility of dissecting cancer subtype-specific dependencies on proteostasis networks to uncover unanticipated cancer vulnerabilities.

Proc Natl Acad Sci U S A. 2016 Aug 9

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Elkabets M, Pazarentzos E, Juric D, Sheng Q, Pelossof RA, Brook S, Benzaken AO, Rodon J, Morse N, Yan JJ, Liu M, Das R, Chen Y, Tam A, Wang H, Liang J, Gurski JM, Kerr DA, Rosell R, Teixidó C, Huang A, Ghossein RA, Rosen N, Bivona TG, Scaltriti M, Baselga J.

Summary
Phosphoinositide-3-kinase (PI3K)-α inhibitors have shown clinical activity in squamous carcinoma (SCC) of head and neck (H&N) bearing PIK3CA mutations or amplification. Studying models of therapeutic resistance we have observed that SCCs cells that become refractory to PI3Kα inhibition maintain PI3K-independent activation of the mammalian target of rapamycin (mTOR). This persistent mTOR activation is mediated by the tyrosine kinase receptor AXL. AXL is overexpressed in resistant tumors from both laboratory models and patients treated with the PI3Kα inhibitor BYL719. AXL dimerizes with and phosphorylates epidermal growth factor receptor (EGFR), resulting in activation of phospholipase Cγ (PLCγ)- protein kinase C (PKC), which in turn activates mTOR. Combined treatment with PI3Kα and either EGFR, AXL, or PKC inhibitors reverts this resistance.

Cancer cell, Apr-13-2015;27(4):533-46.

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