Expanding the landscape of oncogenic drivers and treatment options in acral and mucosal melanomas by targeted genomic profiling.

Despite advancements in treating cutaneous melanoma, patients with acral and mucosal (A/M) melanomas still have limited therapeutic options and poor prognoses. We analyzed 156 melanomas (101 cutaneous, 28 acral, and 27 mucosal) using the Foundation One cancer-gene specific clinical testing platform and identified new, potentially targetable genomic alterations (GAs) in specific anatomic sites of A/M melanomas. Using novel pre-clinical models of A/M melanoma, we demonstrate that several GAs and corresponding oncogenic pathways associated with cutaneous melanomas are similarly targetable in A/M melanomas. Other alterations, including MYC and CRKL amplifications, were unique to A/M melanomas and susceptible to indirect targeting using the BRD4 inhibitor JQ1 or Src/ABL inhibitor dasatinib, respectively. We further identified new, actionable A/M-specific alterations, including an inactivating NF2 fusion in a mucosal melanoma responsive to dasatinib in vivo. Our study highlights new molecular differences between cutaneous and A/M melanomas, and across different anatomic sites within A/M, which may change clinical testing and treatment paradigms for these rare melanomas.

Inflamed immune phenotype predicts favorable clinical outcomes of immune checkpoint inhibitor therapy across multiple cancer types.

BACKGROUND: The inflamed immune phenotype (IIP), defined by enrichment of tumor-infiltrating lymphocytes (TILs) within intratumoral areas, is a promising tumor-agnostic biomarker of response to immune checkpoint inhibitor (ICI) therapy. However, it is challenging to define the IIP in an objective and reproducible manner during manual histopathologic examination. Here, we investigate artificial intelligence (AI)-based immune phenotypes capable of predicting ICI clinical outcomes in multiple solid tumor types. METHODS: Lunit SCOPE IO is a deep learning model which determines the immune phenotype of the tumor microenvironment based on TIL analysis. We evaluated the correlation between the IIP and ICI treatment outcomes in terms of objective response rates (ORR), progression-free survival (PFS), and overall survival (OS) in a cohort of 1,806 ICI-treated patients representing over 27 solid tumor types retrospectively collected from multiple institutions. RESULTS: We observed an overall IIP prevalence of 35.2% and significantly more favorable ORRs (26.3% vs 15.8%), PFS (median 5.3 vs 3.1 months, HR 0.68, 95% CI 0.61 to 0.76), and OS (median 25.3 vs 13.6 months, HR 0.66, 95% CI 0.57 to 0.75) after ICI therapy in IIP compared with non-IIP patients, respectively (p<0.001 for all comparisons). On subgroup analysis, the IIP was generally prognostic of favorable PFS across major patient subgroups, with the exception of the microsatellite unstable/mismatch repair deficient subgroup. CONCLUSION: The AI-based IIP may represent a practical, affordable, clinically actionable, and tumor-agnostic biomarker prognostic of ICI therapy response across diverse tumor types.

Augmented interpretation of HER2, ER, and PR in breast cancer by artificial intelligence analyzer: enhancing interobserver agreement through a reader study of 201 cases.

BACKGROUND: Accurate classification of breast cancer molecular subtypes is crucial in determining treatment strategies and predicting clinical outcomes. This classification largely depends on the assessment of human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER), and progesterone receptor (PR) status. However, variability in interpretation among pathologists pose challenges to the accuracy of this classification. This study evaluates the role of artificial intelligence (AI) in enhancing the consistency of these evaluations. METHODS: AI-powered HER2 and ER/PR analyzers, consisting of cell and tissue models, were developed using 1,259 HER2, 744 ER, and 466 PR-stained immunohistochemistry (IHC) whole-slide images of breast cancer. External validation cohort comprising HER2, ER, and PR IHCs of 201 breast cancer cases were analyzed with these AI-powered analyzers. Three board-certified pathologists independently assessed these cases without AI annotation. Then, cases with differing interpretations between pathologists and the AI analyzer were revisited with AI assistance, focusing on evaluating the influence of AI assistance on the concordance among pathologists during the revised evaluation compared to the initial assessment. RESULTS: Reevaluation was required in 61 (30.3%), 42 (20.9%), and 80 (39.8%) of HER2, in 15 (7.5%), 17 (8.5%), and 11 (5.5%) of ER, and in 26 (12.9%), 24 (11.9%), and 28 (13.9%) of PR evaluations by the pathologists, respectively. Compared to initial interpretations, the assistance of AI led to a notable increase in the agreement among three pathologists on the status of HER2 (from 49.3 to 74.1%, p < 0.001), ER (from 93.0 to 96.5%, p = 0.096), and PR (from 84.6 to 91.5%, p = 0.006). This improvement was especially evident in cases of HER2 2+ and 1+, where the concordance significantly increased from 46.2 to 68.4% and from 26.5 to 70.7%, respectively. Consequently, a refinement in the classification of breast cancer molecular subtypes (from 58.2 to 78.6%, p < 0.001) was achieved with AI assistance. CONCLUSIONS: This study underscores the significant role of AI analyzers in improving pathologists' concordance in the classification of breast cancer molecular subtypes.

Comprehensive Landscape of Cyclin Pathway Gene Alterations and Co-occurrence with FGF/FGFR Aberrations Across Urinary Tract Tumors.

BACKGROUND: Cyclin pathway gene alterations are frequent in urothelial tumors and may co-exist with other important aberrations, leading to therapeutic opportunities. We characterized the landscape of cyclin gene alterations in urothelial and non-urothelial urinary tract (UT) malignancies. PATIENTS AND METHODS: Overall, 6842 urothelial and 897 non-urothelial UT cancers were analyzed (hybrid-capture-based comprehensive genomic profile (Foundation Medicine)). Alteration frequency in cyclin-sensitizing and -resistance genes, and co-occurrence with fibroblast growth factor receptor (FGFR) gene abnormalities were evaluated. RESULTS: Cyclin-activating gene alterations were detected in 47.3% of urothelial and 37.9% of non-urothelial UT cancers. Frequency varied by histology and tumor site. CDKN2A and CDKN2B loss were the most frequent alterations in urothelial tumors (present in 38.5% and 30.4% of patients, respectively). Both genes were less frequently altered in adenocarcinomas (15.2% and 8.9%), but commonly altered in squamous cell carcinomas (74.4% and 39%). Tumors of neuroendocrine origin were relatively silent in activating cyclin alterations, but frequently displayed Rb1 alterations (86% and 83.7% of neuroendocrines and small cell carcinomas). Urachal tumors (n = 79) presented a distinct landscape of cyclin alterations relative to other UT cancers, with less frequent alterations overall. FGF/FGFR genes were altered in 34.9% of urothelial (22.1% in FGFR3), and 19.4% of non-urothelial urinary tract tumors (6.8% FGFR3). Cyclin-activating alterations frequently co-occurred with FGF/FGFR alterations but were in general mutually exclusively with cyclin resistance alterations (RB1/CCNE1). CONCLUSIONS: Cyclin pathway activating alterations are common in urinary tract tumors, but frequency varies with histology and tumors sites. Co-occurrence of cyclin and FGFR pathway alterations may inform therapeutic opportunities.

A Common Cell of Origin for Inflammatory Myofibroblastic Tumor and Lung Adenocarcinoma with ALK rearrangement.

This case signifies the importance of obtaining tumor comprehensive genomic profiling (CGP) as it has utility in cancer type classification and helping in diagnosing recurrence/metastasis or separately occurring primary tumors. CGP can also help guiding treatment as in this case separately occurring Inflammatory Myofibroblastic Tumor had ALK fusion and responded to crizotinib. As treatment progresses, new biopsies should be obtained and CGP used to evaluate for appearance of any new genomic alterations, in order to guide further therapy.

Truncated FGFR2 is a clinically actionable oncogene in multiple cancers.

Somatic hotspot mutations and structural amplifications and fusions that affect fibroblast growth factor receptor 2 (encoded by FGFR2) occur in multiple types of cancer1. However, clinical responses to FGFR inhibitors have remained variable1-9, emphasizing the need to better understand which FGFR2 alterations are oncogenic and therapeutically targetable. Here we apply transposon-based screening10,11 and tumour modelling in mice12,13, and find that the truncation of exon 18 (E18) of Fgfr2 is a potent driver mutation. Human oncogenomic datasets revealed a diverse set of FGFR2 alterations, including rearrangements, E1-E17 partial amplifications, and E18 nonsense and frameshift mutations, each causing the transcription of E18-truncated FGFR2 (FGFR2ΔE18). Functional in vitro and in vivo examination of a compendium of FGFR2ΔE18 and full-length variants pinpointed FGFR2-E18 truncation as single-driver alteration in cancer. By contrast, the oncogenic competence of FGFR2 full-length amplifications depended on a distinct landscape of cooperating driver genes. This suggests that genomic alterations that generate stable FGFR2ΔE18 variants are actionable therapeutic targets, which we confirmed in preclinical mouse and human tumour models, and in a clinical trial. We propose that cancers containing any FGFR2 variant with a truncated E18 should be considered for FGFR-targeted therapies.

Clinical genomic profiling in the management of patients with soft tissue and bone sarcoma.

There are more than 70 distinct sarcomas, and this diversity complicates the development of precision-based therapeutics for these cancers. Prospective comprehensive genomic profiling could overcome this challenge by providing insight into sarcomas' molecular drivers. Through targeted panel sequencing of 7494 sarcomas representing 44 histologies, we identify highly recurrent and type-specific alterations that aid in diagnosis and treatment decisions. Sequencing could lead to refinement or reassignment of 10.5% of diagnoses. Nearly one-third of patients (31.7%) harbor potentially actionable alterations, including a significant proportion (2.6%) with kinase gene rearrangements; 3.9% have a tumor mutational burden ≥10 mut/Mb. We describe low frequencies of microsatellite instability (<0.3%) and a high degree of genome-wide loss of heterozygosity (15%) across sarcomas, which are not readily explained by homologous recombination deficiency (observed in 2.5% of cases). In a clinically annotated subset of 118 patients, we validate actionable genetic events as therapeutic targets. Collectively, our findings reveal the genetic landscape of human sarcomas, which may inform future development of therapeutics and improve clinical outcomes for patients with these rare cancers.

Clustered 8-Oxo-Guanine Mutations and Oncogenic Gene Fusions in Microsatellite-Unstable Colorectal Cancer.

PURPOSE: Colorectal carcinomas (CRCs) with microsatellite-instability (MSI) are enriched for oncogenic kinase fusions (KFs), including NTRK1, RET, and BRAF, but the mechanism underlying this finding is unclear. METHODS: The genomic profiles of 32,218 advanced CRC tumor specimens were analyzed to assess the fusion breakpoints of oncogenic alterations including KFs in microsatellite-stable and microsatellite-unstable CRC. Genomic contexts of such alterations were analyzed to obtain mechanistic insights. RESULTS: Genomic analysis demonstrated that oncogenic fusion breakpoints in MSI tumors do not preferentially involve repetitive or low-complexity sequences. Instead, their junction regions showed pronounced guanine and cytosine bias and elevated mutation frequency at G:C contexts. Elevated mutation frequency at G:C bases in relevant introns predicted prevalence of associated oncogenic fusions in MSI CRCs. CRCs harboring mismatch repair signatures had enrichment of butyrate-producing microbial species, reported to be associated with induction of 8-oxoguanine lesions in the intestine. CONCLUSION: Detailed analysis of breakpoints in MSI-associated KFs support a model in which inefficient repair and/or processing of microbiome-induced clustered 8-oxoguanine damage in MSI CRC contributes to the increased incidence of specific oncogenic fusions.

Deficiency of the splicing factor RBM10 limits EGFR inhibitor response in EGFR-mutant lung cancer.

Molecularly targeted cancer therapy has improved outcomes for patients with cancer with targetable oncoproteins, such as mutant EGFR in lung cancer. Yet, the long-term survival of these patients remains limited, because treatment responses are typically incomplete. One potential explanation for the lack of complete and durable responses is that oncogene-driven cancers with activating mutations of EGFR often harbor additional co-occurring genetic alterations. This hypothesis remains untested for most genetic alterations that co-occur with mutant EGFR. Here, we report the functional impact of inactivating genetic alterations of the mRNA splicing factor RNA-binding motif 10 (RBM10) that co-occur with mutant EGFR. RBM10 deficiency decreased EGFR inhibitor efficacy in patient-derived EGFR-mutant tumor models. RBM10 modulated mRNA alternative splicing of the mitochondrial apoptotic regulator Bcl-x to regulate tumor cell apoptosis during treatment. Genetic inactivation of RBM10 diminished EGFR inhibitor-mediated apoptosis by decreasing the ratio of (proapoptotic) Bcl-xS to (antiapoptotic) Bcl-xL isoforms of Bcl-x. RBM10 deficiency was a biomarker of poor response to EGFR inhibitor treatment in clinical samples. Coinhibition of Bcl-xL and mutant EGFR overcame the resistance induced by RBM10 deficiency. This study sheds light on the role of co-occurring genetic alterations and on the effect of splicing factor deficiency on the modulation of sensitivity to targeted kinase inhibitor cancer therapy.

The Genomics of Colorectal Cancer in Populations with African and European Ancestry.

Black people have a higher incidence of colorectal cancer and worse survival rates when compared with white people. Comprehensive genomic profiling was performed in 46,140 colorectal adenocarcinoma cases. Ancestry-informative markers identified 5,301 patients of African descent (AFR) and 33,770 patients of European descent (EUR). AFR were younger, had fewer microsatellite instability-high (MSI-H) tumors, and had significantly more frequent alterations in KRAS, APC, and PIK3CA. AFR had increased frequency of KRAS mutations, specifically KRASG12D and KRASG13. There were no differences in rates of actionable kinase driver alterations (HER2, MET, NTRK, ALK, ROS1, and RET). In patients with young-onset colorectal cancer (<50 years), AFR and EUR had a similar frequency of MSI-H and tumor mutational burden-high (TMB-H) tumors, and strikingly different trends in APC mutations by age, as well as differences in MAPK pathway alterations. These findings inform treatment decisions, impact prognosis, and underscore the need for model systems representative of the diverse U.S. population. SIGNIFICANCE: KRAS (particularly KRASG12D/G13), APC, and PIK3CA were more frequently altered in AFR who had a lower frequency of MSI-H tumors. There were no differences in actionable kinase driver alterations. In young-onset colorectal cancer, both ancestries had a similar frequency of MSI-H/TMB-H tumors, but strikingly different trends in APC. See related commentary by Eng and Holowatyj, p. 1187. This article is highlighted in the In This Issue feature, p. 1171.

Positive Association Between Location of Melanoma, Ultraviolet Signature, Tumor Mutational Burden, and Response to Anti-PD-1 Therapy.

Emerging evidence suggests a correlation between the tumor mutational burden (TMB) and the response to programmed cell death-1 protein (PD-1) monotherapy across multiple cancer types. In skin cancers, as high TMB is mostly because of ultraviolet (UV) exposure, we hypothesized a correlation between the primary melanoma cutaneous location according to sun exposure and response to anti-PD-1 monotherapy. METHODS: The aim of this study was to analyze, in advanced melanoma, the relationship between TMB, locations according to sun exposure, and response to PD-1 inhibitors. We conducted a prospective multicentric analysis, by sequencing the most recent metastatic sample before PD-1 inhibitors using FoundationOne assay. RESULTS: One hundred two patients were included, with TMB available for 94 cases. In univariate and multivariate linear regression, TMB was significantly associated with sun-exposed areas of the primary melanoma location and with age (coefficients of the association with log-TMB: non-UV location, -1.05; chronic sun-exposed area, 1.12; P value for the location, < 10-5; age, 0.021 per year, P value for age, .002). Molecular UV signature present on the metastatic site was associated with higher TMB (P = .003). Melanomas bearing a high TMB had a higher probability of response to PD-1 inhibitors compared with melanomas with a low TMB, with a dose-dependent effect following an exponential curve and a negative odds ratio of 0.40 (95% CI, 0.20 to 0.72, P = .004) between log-TMB and 6-month progression. CONCLUSION: Cumulative sun exposure related to skin location and molecular UV signature present on the metastatic site appear to be relevant biomarkers directly linked to TMB. Because TMB is not yet available to all for routine clinical use, the location of the primary melanoma in a sun-exposed area may play an important role in clinical decisions regarding therapeutic choice.

Genomic Profiling of Combined Hepatocellular Cholangiocarcinoma Reveals Genomics Similar to Either Hepatocellular Carcinoma or Cholangiocarcinoma.

PURPOSE: Combined hepatocellular cholangiocarcinoma (cHCC-CCA) is a rare, aggressive primary liver carcinoma, with morphologic features of both hepatocellular carcinomas (HCC) and liver cholangiocarcinomas (CCA). METHODS: The genomic profiles of 4,975 CCA, 1,470 HCC, and 73 cHCC-CCA cases arising from comprehensive genomic profiling in the course of clinical care were reviewed for genomic alterations (GA), tumor mutational burden, microsatellite instability status, genomic loss of heterozygosity, chromosomal aneuploidy, genomic ancestry, and hepatitis B virus status. RESULTS: In cHCC-CCA, GA were most common in TP53 (65.8%), TERT (49.3%), and PTEN (9.6%), and 24.6% cHCC-CCA harbored potentially targetable GA. Other GA were predominantly associated with either HCC or CCA, including, but not limited to, TERT, FGFR2, IDH1, and presence of hepatitis B virus. On the basis of these features, a machine learning (ML) model was trained to classify a cHCC-CCA case as CCA-like or HCC-like. Of cHCC-CCA cases, 16% (12/73) were ML-classified as CCA-like and 58% (42/73) cHCC-CCA were ML-classified as HCC-like. The ML model classified more than 70% of cHCC-CCA as CCA-like or HCC-like on the basis of genomic profiles, without additional clinico-pathologic input. CONCLUSION: These findings demonstrate the use of ML for classification as based on a targeted exome panel used during routine clinical care. Classification of cHCC-CCA by genomic features alone creates insights into the biology of the disease and warrants further investigation for relevance to clinical care.

Real-world association of HER2/ERBB2 concordance with trastuzumab clinical benefit in advanced esophagogastric cancer.

Aim: To assess concordance between HER2 status measured by traditional methods and ERBB2 amplification measured by next-generation sequencing and its association with first-line trastuzumab clinical benefit in patients with advanced esophagogastric cancer. Methods: Retrospective analysis of HER2/ERBB2 concordance using a deidentified USA-based clinicogenomic database. Clinical outcomes were assessed for patients with HER2+ advanced esophagogastric cancer who received first-line trastuzumab. Results: Overall HER2/ERBB2 concordance was 87.5%. Among patients who received first-line trastuzumab, concordant HER2/ERBB2 was associated with longer time to treatment discontinuation (adjusted hazard ratio [aHR]: 0.63; 95% CI: 0.43-0.90) and overall survival (aHR: 0.51; 95% CI: 0.33-0.79). ERBB2 copy number ≥25 (median) was associated with longer time to treatment discontinuation (aHR: 0.56; 95% CI: 0.35-0.88) and overall survival (aHR: 0.52; 95% CI: 0.30-0.91). Conclusion: HER2/ERBB2 concordance and higher ERBB2 copy number predicted clinical benefit from trastuzumab.

Lay abstract Trastuzumab is a drug that has been shown to prolong survival in some patients with advanced esophagogastric cancer whose tumor expresses a protein biomarker called HER2. There are different methods for assessing whether a patient's tumor expresses HER2, including but not limited to traditional methods such as immunohistochemistry and in situ hybridization and novel methods such as next-generation sequencing, which detects alterations in the gene (ERBB2) that encodes the HER2 protein. In our study, we assessed concordance between HER2 status (HER2-positive or HER2-negative) measured by traditional methods and ERBB2 amplification measured by next-generation sequencing, to determine whether there was an association between concordance and clinical benefit in patients with advanced esophagogastric cancer treated with trastuzumab. Our results suggest that, when HER2 positivity is detected through traditional methods, both ERBB2 concordance (i.e., agreement that a patient's tumor had the biomarker) and a higher ERBB2 copy number (the amount of the ERBB2 gene expressed by the tumor) were associated with longer time to treatment discontinuation and overall survival in patients with advanced esophagogastric cancer treated with first-line trastuzumab.

Genomic profiling of solid tumors harboring BRD4-NUT and response to immune checkpoint inhibitors.

BACKGROUND: The translocation t(15:19) produces the oncogenic BRD4-NUT fusion which is pathognomonic for NUT carcinoma (NC), which is a rare, but extremely aggressive solid tumor. Comprehensive genomic profiling (CGP) by hybrid-capture based next generation sequencing of 186+ genes of a cohort of advanced cancer cases with a variety of initial diagnoses harboring BRD4-NUT may shed further insight into the biology of these tumors and possible options for targeted treatment. CASE PRESENTATION: Thirty-one solid tumor cases harboring a BRD4-NUT translocation are described, with only 16% initially diagnosed as NC and the remainder carrying other diagnoses, most commonly NSCLCNOS (22%) and lung squamous cell carcinoma (NSCLC-SCC) (16%). The cohort was all microsatellite stable and harbored a low Tumor Mutational Burden (TMB, mean 1.7 mut/mb, range 0-4). In two index cases, patients treated with immune checkpoint inhibitors (ICPI) had unexpected partial or better responses of varying duration. Notably, four cases - including the two index cases - were negative for PD-L1 expression. Neo-antigen prediction for BRD4-NUT and then affinity modeling of the peptide-MHC (pMHC) complex for an assessable index case predicted very high affinity binding, both on a ranked (99.9%) and absolute (33 nM) basis. CONCLUSIONS: CGP identifies BRD4-NUT fusions in advanced solid tumors which carry a broad range of initial diagnoses and which should be re-diagnosed as NC per guidelines. A hypothesized mechanism underlying responses to ICPI in the low TMB, PD-L1 negative index cases is the predicted high affinity of the BRD4-NUT fusion peptide to MHC complexes. Further study of pMHC affinity and response to immune checkpoint inhibitors in patients with NC harboring BRD4-NUT is needed to validate this therapeutic hypothesis.

Structure-function analysis of oncogenic EGFR Kinase Domain Duplication reveals insights into activation and a potential approach for therapeutic targeting.

Mechanistic understanding of oncogenic variants facilitates the development and optimization of treatment strategies. We recently identified in-frame, tandem duplication of EGFR exons 18 - 25, which causes EGFR Kinase Domain Duplication (EGFR-KDD). Here, we characterize the prevalence of ERBB family KDDs across multiple human cancers and evaluate the functional biochemistry of EGFR-KDD as it relates to pathogenesis and potential therapeutic intervention. We provide computational and experimental evidence that EGFR-KDD functions by forming asymmetric EGF-independent intra-molecular and EGF-dependent inter-molecular dimers. Time-resolved fluorescence microscopy and co-immunoprecipitation reveals EGFR-KDD can form ligand-dependent inter-molecular homo- and hetero-dimers/multimers. Furthermore, we show that inhibition of EGFR-KDD activity is maximally achieved by blocking both intra- and inter-molecular dimerization. Collectively, our findings define a previously unrecognized model of EGFR dimerization, providing important insights for the understanding of EGFR activation mechanisms and informing personalized treatment of patients with tumors harboring EGFR-KDD. Finally, we establish ERBB KDDs as recurrent oncogenic events in multiple cancers.

Optimized EGFR Blockade Strategies in EGFR Addicted Gastroesophageal Adenocarcinomas.

PURPOSE: Gastric and gastroesophageal adenocarcinomas represent the third leading cause of cancer mortality worldwide. Despite significant therapeutic improvement, the outcome of patients with advanced gastroesophageal adenocarcinoma is poor. Randomized clinical trials failed to show a significant survival benefit in molecularly unselected patients with advanced gastroesophageal adenocarcinoma treated with anti-EGFR agents. EXPERIMENTAL DESIGN: We performed analyses on four cohorts: IRCC (570 patients), Foundation Medicine, Inc. (9,397 patients), COG (214 patients), and the Fondazione IRCCS Istituto Nazionale dei Tumori (206 patients). Preclinical trials were conducted in patient-derived xenografts (PDX). RESULTS: The analysis of different gastroesophageal adenocarcinoma patient cohorts suggests that EGFR amplification drives aggressive behavior and poor prognosis. We also observed that EGFR inhibitors are active in patients with EGFR copy-number gain and that coamplification of other receptor tyrosine kinases or KRAS is associated with worse response. Preclinical trials performed on EGFR-amplified gastroesophageal adenocarcinoma PDX models revealed that the combination of an EGFR mAb and an EGFR tyrosine kinase inhibitor (TKI) was more effective than each monotherapy and resulted in a deeper and durable response. In a highly EGFR-amplified nonresponding PDX, where resistance to EGFR drugs was due to inactivation of the TSC2 tumor suppressor, cotreatment with the mTOR inhibitor everolimus restored sensitivity to EGFR inhibition. CONCLUSIONS: This study underscores EGFR as a potential therapeutic target in gastric cancer and identifies the combination of an EGFR TKI and a mAb as an effective therapeutic approach. Finally, it recognizes mTOR pathway activation as a novel mechanism of primary resistance that can be overcome by the combination of EGFR and mTOR inhibitors.See related commentary by Openshaw et al., p. 2964.

Landscape of Cyclin Pathway Genomic Alterations Across 5,356 Prostate Cancers: Implications for Targeted Therapeutics.

The cyclin pathway may confer resistance to standard treatments but also offer novel therapeutic opportunities in prostate cancer. Herein, we analyzed prostate cancer samples (majority metastatic) using comprehensive genomic profiling performed by next-generation sequencing (315 genes, >500× coverage) for alterations in activating and sensitizing cyclin genes (CDK4 amplification, CDK6 amplification, CCND1, CCND2, CCND3, CDKN2B [loss], CDKN2A [loss], SMARCB1), androgen receptor (AR) gene, and coalterations in genes leading to cyclin inhibitor therapeutic resistance (RB1 and CCNE1). Overall, cyclin sensitizing pathway genomic abnormalities were found in 9.7% of the 5,356 tumors. Frequent alterations included CCND1 amplification (4.2%) and CDKN2A and B loss (2.4% each). Alterations in possible resistance genes, RB1 and CCNE1, were detected in 9.7% (up to 54.6% in neuroendocrine) and 1.2% of cases, respectively, whereas AR alterations were seen in 20.9% of tumors (~27.3% in anaplastic). Cyclin sensitizing alterations were also more frequently associated with concomitant AR alterations.

Predicting the Pathologic Complete Response After Neoadjuvant Pembrolizumab in Muscle-Invasive Bladder Cancer.

BACKGROUND: In the PURE-01 study (NCT02736266), we aimed to evaluate the ability to predict the pathologic complete response (pT0N0) after pembrolizumab by using clinical and tumor biomarkers. METHODS: In an open-label, single-arm, phase 2 study, 3 courses of 200 mg pembrolizumab preceding radical cystectomy were administered in patients with T2-4aN0M0 muscle-invasive bladder cancer. The analyses included a comprehensive genomic profiling and programmed cell-death-ligand-1 (PD-L1)-combined positive score assessment (CPS; Dako 22C3 antibody) of pre- and posttherapy samples. Multivariable logistic regression analyses evaluated baseline clinical T stage and tumor biomarkers in association with pT0N0 response. Corresponding coefficients were used to develop a calculator of pT0N0 response based on the tumor mutational burden (TMB), CPS, and the clinical T stage. Decision-curve analysis was also performed. All statistical tests were 2-sided. RESULTS: From February 2017 to June 2019, 112 patients with biomarker data were enrolled (105 with complete TMB and CPS data). Increasing TMB and CPS values featured a linear association with logistic pT0N0 probabilities (P = .02 and P = .004, respectively). For low TMB values (≤11 mut/Mb, median value, n = 53), pT0N0 probability was not associated with increasing CPS. Conversely, for high TMB values (>11 mut/Mb, n = 52), pT0N0 was statistically significantly associated with higher CPS (P = .004). The C index of the pT0N0 probability calculator was 0.77. On decision-curve analysis, the net benefit of the model was higher than the "treat-all" option within the clinically meaningful threshold probabilities of 40%-50%. CONCLUSIONS: The study presents a composite biomarker-based pT0N0 probability calculator that reveals the complex interplay between TMB and CPS, added to the clinical T stage.

Targetable BRAF and RAF1 Alterations in Advanced Pediatric Cancers.

RAF family protein kinases signal through the MAPK pathway to orchestrate cellular proliferation, survival, and transformation. Identifying BRAF alterations in pediatric cancers is critically important as therapeutic agents targeting BRAF or MEK may be incorporated into the clinical management of these patients. In this study, we performed comprehensive genomic profiling on 3,633 pediatric cancer samples and identified a cohort of 221 (6.1%) cases with known or novel alterations in BRAF or RAF1 detected in extracranial solid tumors, brain tumors, or hematological malignancies. Eighty percent (176/221) of these tumors had a known-activating short variant (98, 55.7%), fusion (72, 40.9%), or insertion/deletion (6, 3.4%). Among BRAF altered cancers, the most common tumor types were brain tumors (74.4%), solid tumors (10.8%), hematological malignancies (9.1%), sarcomas (3.4%), and extracranial embryonal tumors (2.3%). RAF1 fusions containing intact RAF1 kinase domain (encoded by exons 10-17) were identified in seven tumors, including two novel fusions TMF1-RAF1 and SOX6-RAF1. Additionally, we highlight a subset of patients with brain tumor with positive clinical response to BRAF inhibitors, demonstrating the rationale for incorporating precision medicine into pediatric oncology. IMPLICATIONS FOR PRACTICE: Precision medicine has not yet gained a strong foothold in pediatric cancers. This study describes the landscape of BRAF and RAF1 genomic alterations across a diverse spectrum of pediatric cancers, primarily brain tumors, but also encompassing melanoma, sarcoma, several types of hematologic malignancy, and others. Given the availability of multiple U.S. Food and Drug Administration-approved BRAF inhibitors, identification of these alterations may assist with treatment decision making, as described here in three cases of pediatric cancer.