Yoon, Harry H.

TPS4138 Background: Apatinib is an orally administered, highly selective tyrosine kinase inhibitor of VEGFR-2 that has been studied in many clinical trials, primarily in China, treating various solid tumors. Based on the results of the Chinese Phase 3 study, apatinib was approved in China for the treatment of advanced gastric cancer (GC), but apatinib has yet to be evaluated in a randomized placebo-controlled study in the rest of the world. ANGEL is a multinational, placebo controlled, Phase 3 study investigating the efficacy and safety of apatinib in advanced GC patients in North America, Europe, and Asia Pacific. Methods: Main eligibility criteria include patients with advanced or metastatic adenocarcinoma of the stomach or gastroesophageal junction for whom at least 2 prior lines of standard chemotherapy had failed, ECOG performance status ≤ 1, and disease progression < 6 months after last chemotherapy treatment. Approximately 459 patients will be randomized in a 2:1 ratio to receive continuous 28-day cycles of apatinib 700 mg or a matched placebo daily with best supportive care until disease progression, intolerable toxicity or withdrawal of consent. Stratification factors include geographic region (Asia vs. North America/Europe), disease measurability, prior ramucirumab treatment, and treatment therapy line (3rd or 4th). Primary endpoint is overall survival (OS) in the intent-to-treat population, and secondary endpoints are progression free survival (PFS), objective response rate (ORR), disease control rate (DCR), quality of life, and safety. The primary analysis of OS will be conducted in intention-to-treat population using a stratified log-rank test at the two-sided alpha = 0.05 level of significance. If the primary analysis of OS is statistically significant, then PFS and ORR will be analyzed. All other secondary efficacy endpoints will be analyzed using two-sided tests at the alpha = 0.05 level of significance. Enrollment opened Feb 2017. Clinical trial information: NCT03042611.

4003 Background: Pembro has shown promising antitumor activity and manageable safety in a phase 1 study of pts with previously treated advanced gastric cancer. We conducted a global, multicohort, phase 2 study of pembro in pts with advanced gastric or gastroesophageal junction (G/GEJ) cancer (KEYNOTE-059;NCT02335411). Methods: Cohort 1 enrolled 259 pts, aged ≥18 y with measurable recurrent or metastatic G/GEJ adenocarcinoma who had progressed on ≥2 prior chemotherapy regimens and had ECOG PS 0-1. Pts received pembro 200 mg Q3W up to 2 y or up to disease progression, investigator/pt decision to withdrawal, or unacceptable toxicity. PD-L1+pts had expression in ≥1% tumor or stromal cells using IHC (22C3 antibody). Primary end points: ORR (RECIST 1.1, by central review), safety, and tolerability. Results: Of 259 pts in cohort 1, 76.4% were men; median age was 62.0 y. 51.7% and 48.3% received pembro as 3rd-line (3L) and 4L+ therapy, respectively. 57.1% had PD-L1+ tumors. At data cutoff (Oct 19, 2016), median duration of follow-up was 5.4 mo (range, 0.5 to 18.7). Overall ORR (CR + PR) was 11.2% (95% CI, 7.6-15.7); 1.9% of pts (95% CI, 0.6-4.4) had CR, 9.3% had PR (95% CI, 6.0-13.5), 17% (95% CI, 12.6-22.1) had SD, and 55.6% (95% CI, 49.3-61.7) had PD. Median DOR was 8.1 mo (range, 1.4+ to 15.1+). ORR was 14.9% (95% CI, 9.4-22.1) in 3L pts and 7.2% (95% CI, 3.3-13.2) in 4L+. In PD-L1+ pts, ORR was 15.5% (95% CI, 10.1-22.4) with 2.0% (95% CI, 0.4-5.8) CR and 13.5% (95% CI, 8.5-20.1) PR; in PD-L1– pts, ORR was 5.5% (95% CI, 2.0-11.6), with 1.8% (95% CI, 0.2-6.5) CR and 3.7% (95% CI, 1.0-9.1) PR. In 3L pts with PD-L1+ tumors, ORR was 21.3% (95% CI, 12.7-32.3), with 4.0% (95% CI, 0.8-11.2) CR; in 3L pts with PD-L1– tumors, ORR was 6.9% (95% CI, 1.9-16.7), with 3.4% (95% CI, 0.4-11.9) CR. Grade 3-5 treatment-related AEs (TRAEs) occurred in 43 pts (16.6%). TRAEs led to discontinuation in 2 pts (abnormal LFT, bile duct stenosis) and were fatal in 2 pts (acute kidney injury, pleural effusion). Conclusions: Pembro showed encouraging efficacy and manageable safety after ≥2 prior lines of therapy in pts with advanced G/GEJ cancer in this large phase 2 trial. Survival and additional biomarker data, including MSI status, will be presented. Clinical trial information: NCT02335411.

Abstract Lesson Learned Panitumumab plus irinotecan is not active for the treatment of esophageal adenocarcinoma. Background Esophageal adenocarcinoma (EAC) is a lethal cancer with increasing incidence. Panitumumab (Pa) is a fully humanized IgG2 monoclonal antibody against human EGFR. Cetuximab (Cx) combined with irinotecan (Ir) is active for second-line treatment of colorectal cancer. This phase II study was designed to evaluate Pa plus Ir as second-line therapy for advanced EAC. Methods The primary endpoint was response rate (RR). Patients with one prior treatment were given Pa 9 mg/m2 on day 1 and Ir 125 mg/m2 on days 1 and 8 of each 21-day cycle. Inclusion criteria were confirmed EAC, measurable disease, no prior Ir or Pa, performance status &lt;2, and normal organ function. Results Twenty-four patients were enrolled; 18 were eligible and evaluable. These patients were all white, with a median age of 62.5 years (range, 33–79 years), and included 15 men and 3 women. The median number of cycles was 3.5. The most common grade 1–2 adverse events were fatigue, diarrhea, anemia, leukopenia, and hypoalbuminemia. Grade 3–4 adverse events included hematologic, gastrointestinal, electrolyte, rash, fatigue, and weight loss. The median follow-up was 7.2 months (range, 2.3–14 months). There were no complete remissions. The partial response rate was 6% (1/18; 95% confidence interval [CI], 0.01–0.26). The clinical benefit (partial response [PR] plus stable disease [SD]) rate was 50%. The median overall survival was 7.2 months (95% CI, 4.1–8.9) with an 11.1% 1-year survival rate. The median progression-free survival was 2.9 months (95% CI, 1.6–5.3). Conclusion Irinotecan and panitumumab as second-line treatment for advanced EAC are not active.

Abstract Checkpoint inhibitors targeted at programmed cell death-1 receptor (PD-1) and its ligand (PD-L1) can result in significant benefit to a small proportion of patients with cancer, including those with tumors of the stomach and gastroesophageal junction. These drugs are now approved for several solid tumors, including the recent accelerated approval of pembrolizumab for gastroesophageal adenocarcinomas in the third-line setting and beyond based on the KEYNOTE-059 phase II trial. Data are lacking on the efficacy of chemotherapy after progression on PD-1 blockade in metastatic gastroesophageal adenocarcinoma. This report describes the exceptional response of two patients who received ramucirumab plus paclitaxel after progressive disease on pembrolizumab. This early clinical observation suggests that the sequence of administration of PD-1 blockade and chemotherapy may be important in this disease.

2 Background: Testing for HER2 in EAC has become routine given its ability to predict benefit from HER2-targeted therapy. HER2 protein analysis by immunohistochemistry (IHC) is more rapid and generally less expensive than assessment of gene amplification by fluorescence in situ hybridization (FISH). However, the accuracy of IHC for predicting HER2 amplification has not been examined in a large EAC cohort. Methods: Surgical EAC specimens were examined from 675 patients who underwent curative resection at a single institution without preoperative therapy. Tumors were located in the esophagus (47%) or gastroesophageal junction (53%); most were node-positive (73%). Every tumor was evaluated by IHC in parallel with FISH in a blinded manner using FDA-approved assays. A consensus IHC score was determined by 2 pathologists using tumor-specific criteria (negative, 0 or 1+; equivocal, 2+; positive, 3+). Gene amplification by FISH was defined as a HER2/CEP17ratio ≥ 2. Results: HER2 amplification was detected in 89% of IHC 3+ cases, 13% of IHC 2+ cases, and 4% of IHC 0-1+ cases (Table). Accordingly, using FISH as the reference standard, the positive predictive value (PPV) of a positive IHC test (3+) was 89% (79/89 [95% CI 82%-95%]), and the negative predictive value of a negative IHC test (0-1+) was 96% (401/417 [94%-98%]). Importantly, the PPV of an equivocal IHC score (2+) for detecting HER2 amplification was 13% (22/169 [8%-18%]). Conclusions: In the largest study to date comparing HER2 testing methods in EAC, a negative IHC result (0 or 1+) nearly excludes the presence of gene amplification by FISH. Whereas a positive IHC result (3+) strongly predicts for the presence of amplification, an equivocal IHC result (2+) is a weak predictor. These findings in EAC support a HER2 testing algorithm where IHC is used for initial screening and FISH testing is restricted to cases with equivocal IHC results. [Table: see text]

460 Background: The immune response has emerged as a strong prognostic factor in colon cancer. Whereas CD8+ T cells mediate antitumor response, regulatory T cells expressing FoxP3+ can antagonize this effect, though prognostic data conflict. These markers have yet to be analyzed with MMR status, which is important since dMMR tumors show enhanced immune response. Methods: CD8+ and FoxP3+ density were analyzed by immunohistochemistry (IHC) in resected stage II and III colon carcinomas (N = 216) from participants in phase III adjuvant 5-fluorouracil-based trials. High vs low immune density was dichotomized at the median. MMR status, determined by IHC or analysis of microsatellite instability, was categorized as dMMR (12%) or proficient MMR (pMMR). Cox models, stratified by study, were adjusted for age, stage, grade and, where noted, MMR. Results: The association of FoxP3+ density with overall survival (OS) differed by CD8+ density (P for interaction = .040). By multivariable analysis, FoxP3+high was significantly associated with improved OS in CD8+low tumors (hazard ratio 0.43 [95% confidence interval 0.19 – 0.95]; P = .030], but not in CD8+high tumors (P = .91). Results were consistent after MMR adjustment. We then determined their prognostic impact in the larger pMMR subset (N = 119). Tumors with high FoxP3+ were associated with improved OS in cases with low, but not high, CD8+ density ( Table ). These patients (FoxP3+high, CD8+low) had similar 5-year OS rates as 107 dMMR cases from parent studies (89% vs 80%; P = .74), despite having distinct clinicopathologic features. Conclusions: The prognostic impact of FoxP3+ T cells depends on CD8+, indicating the importance of analyzing both in combination. High FoxP3+ exerts a paradoxically favorable survival impact, but only when CD8+ is low. Survival in pMMR tumors with high FoxP3+ and low CD8+ was similar to that of dMMR tumors, indicating that a favorable pMMR subset can be identified. [Table: see text]

Although HER2‐positive breast cancers demonstrate a propensity for central nervous system (CNS) metastasis, it is unknown whether other HER2‐positive tumors, including adenocarcinomas of the esophagus/gastroesophageal junction (EAC), share this characteristic. Insight into this association may inform the development of HER2‐targeted therapies that penetrate the blood‐brain barrier. We examined HER2 overexpression and gene amplification in 708 patients with EAC who underwent curative‐intent surgery during a time period (1980–1997) when no patient received HER2‐targeted therapy. We identified patients whose site of first cancer recurrence was CNS and those who had a CNS relapse at any time. After a median follow‐up of 61.2 months, 3.4% (24/708) of patients developed CNS relapse (all involved the brain). Patients with HER2‐positive (vs ‐negative) primary tumors showed a higher 5‐year cumulative incidence of CNS relapse as first recurrence (5.8% vs. 1.2%; p = 0.0058) and at any time (8.3% vs. 2.4%; p = 0.0062). In a multivariable model that included covariates previously associated with HER2 or with CNS relapse in breast cancer, HER2 positivity was the only variable that was statistically significantly associated with shorter time to CNS relapse as first recurrence (p = 0.0026) or at any time (hazard ratio 4.3 [95% confidence interval 1.8 to 10.3]; p = 0.001). These are the first data in a non‐breast cancer to demonstrate an association between HER2 positivity and higher CNS relapse risk after surgery, and suggest that HER2‐positive EACs have a predilection for CNS metastases.