First-line panitumumab plus docetaxel and cisplatin in advanced gastric and gastro-oesophageal junction adenocarcinoma: results of a phase II trial

Purpose Panitumumab is extensively used for RAS-WT metastatic colorectal cancer. This study assessed the efficacy and safety of panitumumab plus first-line chemotherapy [docetaxel (DOC) and cisplatin (CIS)] in treatment-naive advanced gastric or gastro-oesophageal junction (GEJ) adenocarcinoma (ADC) patients. Methods Phase II, open-label, single-arm study includes treatment-naive advanced gastric or GEJ-ADC patients from ten Spanish centres. Patients received panitumumab (6 mg/kg) plus DOC and CIS (50 mg/m(2) both) every 2 weeks until disease progression, unacceptable toxicity, or patient withdrawal. Primary endpoint: objective response rate (ORR); main secondary endpoints: disease control rate (DCR), duration of response (DoR), time to progressive disease (TTP), progression-free-survival (PFS), overall survival (OS), and safety. Results Forty-four patients were included; median age: 67.8 (range 43.3-82.7) years, 68.2% male. The ORR was 27.3% (95% CI 15.0, 42.8); median PFS and OS: 5.0 (95% CI 3.6, 6.9) and 7.2 (5.5, 9.0) months, respectively. Median TTP, DCR and DoR: 5.3 (range 3.8-7.0) months, 70.5% (95% CI 54.8, 83.2%), and 4.8 (1.8, NE) months. Median panitumumab treatment duration: 11.9 (range 0.1-34.9) weeks; 25.0% patients had a dose reduction and 40.9% discontinued treatment. Grade 3-4 adverse events (AEs): 68.2%/22.2% patients. Most common AEs: asthenia (75.0%) and mucosal inflammation (54.5%). Serious AEs were experienced by 54.6% patients; 9.1%, 13.6%, and 15.9% related to panitumumab, DOC, and CIS, respectively. Three (6.8%) patients died due to AEs not related to study treatment. Conclusions The addition of panitumumab to standard chemotherapy as the first-line treatment in advanced gastric or GEJ-ADC does not appear to improve the efficacy outcomes.