Atezolizumab + trastuzumab + XELOX: A promising combination in advanced gastric cancer

Adding atezolizumab to the combination of trastuzumab plus capecitabine and oxaliplatin chemotherapy (XELOX) helps improve treatment response in patients with ERBB2-positive locally advanced resectable gastric cancer (GC) and gastroesophageal junction (GEJ) adenocarcinoma, according to the results of the open-label phase II trial conducted in China.

A total of 42 patients (93 percent male) with resectable locally advanced ERBB2-positive GC or adenocarcinoma of the GEJ were enrolled. They were randomly assigned to receive perioperative treatment with either atezolizumab plus trastuzumab plus XELOX (arm A, n=21; median age 61 years) or trastuzumab plus XELOX (arm B, n=21; median age 65 years) for three neoadjuvant cycles (3 weeks per cycle) and five adjuvant cycles.

The primary efficacy endpoint of the percentage of patients achieving pathological complete response (pCR) following completion of neoadjuvant therapy and surgery was significantly greater in arm A than arm B (38 percent vs 14 percent; difference, 23.8 percent, 90 percent confidence interval, 1.3–44.7). Factors associated with a better pCR rate in arm A included younger age (<65 years), male sex, and intestinal Lauren classification.

On the other hand, median event-free survival, disease-free survival, and overall survival were not reached.

In terms of safety, treatment-emergent adverse events (TEAEs) occurred in all patients in arm A and in arm B. Grade 3 or higher TEAEs were documented in 57 percent of patients in arm A and 67 percent in arm B, while serious TEAEs were reported in 29 percent and 10 percent of patients in the respective arms.