Steven Brad Maron

Genomic Heterogeneity as a Barrier to Precision Medicine in Gastroesophageal Adenocarcinoma

Gastroesophageal adenocarcinoma (GEA) is a lethal disease where targeted therapies, even when guided by genomic biomarkers, have had limited efficacy. A potential reason for the failure of such therapies is that genomic profiling results could commonly differ between the primary and metastatic tumors. To evaluate genomic heterogeneity, we sequenced paired primary GEA and synchronous metastatic lesions across multiple cohorts, finding extensive differences in genomic alterations, including discrepancies in potentially clinically relevant alterations. Multiregion sequencing showed significant discrepancy within the primary tumor (PT) and between the PT and disseminated disease, with oncogene amplification profiles commonly discordant. In addition, a pilot analysis of cell-free DNA (cfDNA) sequencing demonstrated the feasibility of detecting genomic amplifications not detected in PT sampling. Lastly, we profiled paired primary tumors, metastatic tumors, and cfDNA from patients enrolled in the personalized antibodies for GEA (PANGEA) trial of targeted therapies in GEA and found that genomic biomarkers were recurrently discrepant between the PT and untreated metastases. Divergent primary and metastatic tissue profiling led to treatment reassignment in 32% (9/28) of patients. In discordant primary and metastatic lesions, we found 87.5% concordance for targetable alterations in metastatic tissue and cfDNA, suggesting the potential for cfDNA profiling to enhance selection of therapy.Significance: We demonstrate frequent baseline heterogeneity in targetable genomic alterations in GEA, indicating that current tissue sampling practices for biomarker testing do not effectively guide precision medicine in this disease and that routine profiling of metastatic lesions and/or cfDNA should be systematically evaluated. Cancer Discov; 8(1); 37-48. ©2017 AACR.See related commentary by Sundar and Tan, p. 14See related article by Janjigian et al., p. 49This article is highlighted in the In This Issue feature, p. 1.

Targeted Therapies for Targeted Populations: Anti-EGFR Treatment for EGFR-Amplified Gastroesophageal Adenocarcinoma

Previous anti-EGFR trials in unselected patients with gastroesophageal adenocarcinoma (GEA) were resoundingly negative. We identified EGFR amplification in 5% (19/363) of patients at the University of Chicago, including 6% (8/140) who were prospectively screened with intention-to-treat using anti-EGFR therapy. Seven patients received ≥1 dose of treatment: three first-line FOLFOX plus ABT-806, one second-line FOLFIRI plus cetuximab, and three third/fourth-line cetuximab alone. Treatment achieved objective response in 58% (4/7) and disease control in 100% (7/7) with a median progression-free survival of 10 months. Pretreatment and posttreatment tumor next-generation sequencing (NGS), serial plasma circulating tumor DNA (ctDNA) NGS, and tumor IHC/FISH for EGFR revealed preexisting and/or acquired genomic events, including EGFR-negative clones, PTEN deletion, KRAS amplification/mutation, NRAS, MYC, and HER2 amplification, and GNAS mutations serving as mechanisms of resistance. Two evaluable patients demonstrated interval increase of CD3+ infiltrate, including one who demonstrated increased NKp46+, and PD-L1 IHC expression from baseline, suggesting an immune therapeutic mechanism of action. EGFR amplification predicted benefit from anti-EGFR therapy, albeit until various resistance mechanisms emerged.Significance: This paper highlights the role of EGFR inhibitors in EGFR-amplified GEA-despite negative results in prior unselected phase III trials. Using serial ctDNA and tissue NGS, we identified mechanisms of primary and acquired resistance in all patients, as well as potential contribution of antibody-dependent cell-mediated cytotoxicity to their clinical benefit. Cancer Discov; 8(6); 696-713. ©2018 AACR.See related commentary by Strickler, p. 679This article is highlighted in the In This Issue feature, p. 663.

Novel Targeted Therapies for Esophagogastric Cancer

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) is increasing in incidence. GEC, including GC and EGJ, is treated uniformly in the metastatic setting. Overall survival in the metastatic setting remains poor. Molecular characterization of GEC has identified mutations and copy number variations, along with other oncogenes, biomarkers, and immuno-oncologic checkpoints that may serve as actionable therapeutic targets. This article reviews these key aberrations, their impact on protein expression, therapeutic implications, and clinical directions within each pathway.

Update on Gastroesophageal Adenocarcinoma Targeted Therapies

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) incidence is rising. GC and EGJ, together, are treated uniformly in the metastatic setting as GEC. Overall survival in the metastatic setting remains poor, with few molecular targeted approaches having been successfully incorporated into routine care to date-only first-line anti-HER2 therapy for ERBB2 amplification and second-line anti-VEGFR2 therapy. This article reviews aberrations in epidermal growth factor receptor, MET, and ERBB2, their therapeutic implications, and future directions in targeting these pathways.

Pembrolizumab for treatment of advanced gastric and gastroesophageal junction adenocarcinoma.

Pembrolizumab is a monoclonal antibody directed against PD-1 that is US FDA approved for treatment of advanced PD-L1 positive gastric and gastroesophageal junction adenocarcinoma in patients who have progressed on at least two prior lines of chemotherapy. This article summarizes the clinical evidence regarding safety, tolerability and efficacy of pembrolizumab in this setting. In addition, this article describes the investigational use of pembrolizumab as first- and second-line therapy and in combination with other treatments. Finally, this review compares other checkpoint inhibitors to pembrolizumab for the treatment of this disease, and explores predictive biomarkers of response to PD-1 blockade.

Obstruction predicts worse long-term outcomes in stage III colon cancer: A secondary analysis of the N0147 trial

Background: Patients with colon cancer often present with obstruction. Large series have reported obstruction among the high‐risk features, yet prospective data on its specific prognostic influence are lacking. We hypothesized that obstruction is an independent risk factor for poor prognosis in patients with stage III colon cancer. Methods: N0147 was a trial conducted between 2004 and 2009 that randomly assigned patients with stage III colon cancer to adjuvant regimens of folinic acid (leucovorin calcium), fluorouracil, and oxaliplatin or fluorouracil, leucovorin, and irinotecan, with or without cetuximab. Patient‐level data from the control chemotherapy‐only arms were obtained. Patient, tumor, and treatment characteristics were abstracted. Disease‐free survival and overall survival were estimated by the Kaplan‐Meier method. Proportions were compared by χ2 and Fisher exact tests. Univariable and multivariable survival analyses were performed using Cox proportional hazards models. Results: Of 1,543 patients with stage III colon cancer, 250 (16.2%) presented with obstruction. Patients with obstruction were equally likely to complete 12 cycles of adjuvant chemotherapy (75.9% vs 77.1%, P = .6). With median follow‐up time of 30.9 months among survivors, five‐year overall survival and disease‐free survival were worse among patients with obstruction (overall survival 67.7% vs 78.0%, P < .001; disease‐free survival 53.9% vs 67.0%, P < .0001). On multivariable analysis, obstruction remained significantly associated with worse survival after adjusting for T stage, N stage, performance status, age, sex, histologic grade, and body mass index (overall survival hazard ratio 1.57, 95% confidence interval 1.12–2.20, P = .001; disease‐free survival 1.52, 95% confidence interval 1.18–1.95, P < .001). Conclusion: In this prospectively followed cohort of patients with stage III colon cancer treated with adjuvant chemotherapy, obstruction was associated with recurrence and worse survival. Moreover, this effect was independent of T and N stage and histologic grade. These results suggest that obstruction should be incorporated into novel risk‐stratification models.

The effect of pre-existing mental health comorbidities on the stage at diagnosis and timeliness of care of solid tumor malignances in a Veterans Affairs (VA) medical center

There are limited data on the impact of mental health comorbidities (MHC) on stage at diagnosis and timeliness of cancer care. Axis I MHC affect approximately 30% of Veterans receiving care within the Veterans Affairs (VA) system. The purpose of this study was to compare stage at diagnosis and timeliness of care of solid tumor malignancies among Veterans with and without MHC. We performed a retrospective analysis of 408 charts of Veterans with colorectal, urothelial, and head/neck cancer diagnosed and treated at VA Connecticut Health Care System (VACHS) between 2008 and 2011. We collected demographic data, stage at diagnosis, medical and mental health co‐morbidities, treatments received, key time intervals, and number of appointments missed. The study was powered to assess for stage migration of 15–20% from Stage I/II to Stage III/IV. There was no significant change in stage distribution for patients with and without MHC in the entire study group (p = 0.9442) and in each individual tumor type. There were no significant differences in the time intervals from onset of symptoms to initiation of treatment between patients with and without MHC (p = 0.1135, 0.2042 and 0.2352, respectively). We conclude that at VACHS, stage at diagnosis for patients with colorectal, urothelial and head and neck cancers did not differ significantly between patients with and without MHC. Patients with MHC did not experience significant delays in care. Our study indicates that in a medical system in which mental health is integrated into routine care, patients with Axis I MHC do not experience delays in cancer care.