Efficacy and safety of first-line systemic chemotherapy with epirubicin, cisplatin plus 5-fluorouracil and docetaxel, cisplatin plus 5-fluorouracil regimens in locally advanced inoperable or metastatic gastric or gastroesophageal junction adenocarcinoma: A prospective phase II study from South India

4560 Background: RC48-ADC is an antibody-drug conjugate (ADC) drug comprised of a novel humanized anti-HER2 IgG1, a linker, and a microtubule inhibitor, MMAE. The MoA included inhibition of HER2 signal pathway and cytotoxicity of MMAE. RC48-ADC has demonstrated promising anti-tumor activity in pre-clinical and early clinical studies. The current study is designed to evaluate the efficacy and safety of RC48-ADC in heavily treated patients with HER2-overexpressing (IHC 2+ or 3+) gastric or gastro-esophageal junction cancers. Methods: This is an open-label, multicenter, single-arm, phase II study. Eligibility criteria include: histologically confirmed gastric or gastro-esophageal junction cancers, HER2-overexpression (IHC 2+ or 3+), ECOG PS 0-1, post-to ≥2 prior systemic treatment. The patients received RC48-ADC, 2.5 mg/kg, q2w until disease progression, unacceptable toxicity, withdrawal, or study termination. The primary endpoint was ORR. PFS, OS, and safety were also evaluated. Results: Patient enrollment started in July 2017, and completed in November 2019. By the data cut-off date on 17-Dec-2019, 127 patients were enrolled. The median age was 58 years. At baseline, 59 patients (46.5%) had received ≥ 3 lines prior treatment. For the overall 127 patients, the investigator-assessed confirmed ORR was 18.1% (95% CI: 11.8%, 25.9%). Sub-group ORR was 19.4% and 16.9% for the patients post to 2 lines and ≥ 3 lines, respectively. For the 111 patients who were monitored for ≥ 2 cycles of efficacy assessments (i.e. 12 weeks), the ORR was 20.7% (95% CI: 13.6%, 29.5%). For the 127 patients, the mPFS was 3.8 months (95% CI: 2.7, 4.0, 89 events [70.1%]) and the mOS was 7.6 months (95% CI: 6.6, 9.2, 52 events [40.9%]). The most commonly reported treatment-related AEs were leukopenia (52.0%), alopecia (51.2%), neutropenia (48.0%), and fatigue (42.5%). Conclusions: RC48-ADC demonstrated a clinically meaningful response and survival benefit in the heavily treated patients with HER2-overexpressing gastric or gastro-esophageal junction cancers. The safety profile was in line with the previously reported data of RC48-ADC. RC48-ADC showed positive benefit/risk ratio for the target population. Clinical trial information: NCT03556345 .

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KEYlargo: A phase II study of first-line pembrolizumab (P), capecitabine (C), and oxaliplatin (O) in HER2-negative gastroesophageal (GE) adenocarcinoma.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.3_suppl.228 ◽

2021 ◽

Vol 39 (3_suppl) ◽

pp. 228-228

Author(s):

Hope Elizabeth Uronis ◽

Christel Rushing ◽

Gerard C. Blobe ◽

Shiaowen David Hsu ◽

Niharika B. Mettu ◽

...

Keyword(s):

Phase Ii ◽

Gastroesophageal Junction ◽

Single Agent ◽

Locally Advanced ◽

Progression Free Survival ◽

Complete Response ◽

Clinical Activity ◽

First Line ◽

Tumor Biopsy ◽

Gastroesophageal Junction Adenocarcinoma

228 Background: Gastric and esophageal adenocarcinomas are a leading cause of cancer death worldwide. Many of these patients (pts) present with locally advanced unresectable or metastatic disease and are treated with combination cytotoxic chemotherapy. Single agent P is FDA approved for patients with recurrent locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma (GEJ) whose tumors have a combined positive score (CPS) ≥ 1 after disease progression on or after two lines of therapy including fluoropyrimidine and platinum and her2/neu-targeted therapy (if indicated). More effective therapy is needed earlier in the disease trajectory. We conducted a single-arm phase II trial to establish the safety and efficacy of first-line C and O + P. Methods: Pts with previously untreated metastatic GE adenocarcinoma regardless of PDL-1 status received intravenous (IV) P 200mg with IV O 130mg/m2 every three weeks and oral C 850mg/m2 twice daily for 14 days on/7 days off. After the 6 patient safety cohort, pts first completed a biomarker cycle that included fresh tumor biopsy before P and one week after P before chemotherapy started. Archived FFPE tumor samples were also obtained from all pts with available tissue. The primary endpoint was progression free survival (PFS); secondary endpoints included response rate (RR) and overall survival (OS). Results: 36 pts were enrolled and 34 pts were evaluable for efficacy (1 pt withdrew for personal reasons before end of cycle 1 and 1 pt had immune-related toxicity during cycle 1 and was taken off study before any efficacy assessment). 9 pts (26%) had an esophageal primary, 18 pts (53%) had a GEJ primary and 7 pts (21%) had a gastric primary. Median PFS was 7.6 months [95% CI: 5.8 to 12.2], RR was 72.7% [95% CI: 57% to 88%], and median OS was 15.8 months [95% CI: 11.6 to NE]. 27 patients (81.8%) had decrease in disease burden (ranging from -19% to -100%). After > 18 months of follow-up, 5 patients remained in durable complete response (CR). Immune-mediated treatment related adverse events (TRAEs) included thyroid disorders (n=5; 14%), colitis (n=4; 11%), adrenal insufficiency (n=2; 5%), and type 1 diabetes (n=1). Sixteen patients (44%) experienced grade 3 or 4 TRAEs. There were no grade 5 TRAEs. Conclusions: The combination of C and O + P had acceptable safety and significant clinical activity. These promising results indicate that C and O + P merits further study as a first line option for patients with unresectable locally advanced or metastatic GE adenocarcinoma. Updated survival and correlative data will be presented. Clinical trial information: NCT03342937.

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