Zolbetuximab Plus Chemotherapy as First-Line Treatment in Patients with Claudin 18.2-Positive, HER2-Negative, Locally Advanced Unresectable or Metastatic Gastric or Gastroesophageal Junction Adenocarcinoma: Korean Population Subgroup-Combined Efficacy and Safety Analysis from SPOTLIGHT and GLOW

Abstract

Purpose: The phase 3 SPOTLIGHT and GLOW trials, in patients with claudin 18 isoform 2-positive, human epidermal growth factor receptor 2-negative, locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma, demonstrated statistically significant and clinically meaningful improvement in progression-free survival (PFS) and overall survival (OS) with first-line zolbetuximab plus chemotherapy versus placebo plus chemotherapy. This analysis evaluated efficacy and safety in the Korean subgroup from SPOTLIGHT and GLOW.

Materials and methods: Patients were randomized 1:1 to receive zolbetuximab plus chemotherapy or placebo plus chemotherapy (mFOLFOX6 [modified folinic acid, 5-fluorouracil, and oxaliplatin] or CAPOX [capecitabine and oxaliplatin]). Primary endpoint was PFS, assessed per RECIST v1.1 by independent review committee. Other efficacy and safety parameters were assessed.

Results: The Korean subgroup consisted of 49 patients in the zolbetuximab group and 47 in the placebo group. Median PFS (95% confidence interval [CI]) was 12.3 months (7.3-15.3), and median OS was 30.5 months (16.1-45.5) with zolbetuximab versus 8.1 months (4.2-10.4) and 15.8 months (11.8-19.7) with placebo, respectively. Most common TEAEs in patients who received zolbetuximab versus placebo were nausea (79.6% vs. 53.2%), vomiting (55.1% vs. 21.3%), and decreased appetite (53.1% vs. 23.4%). Treatment-related TEAEs led to discontinuation of zolbetuximab and placebo in 4.1% and 2.1% of patients, respectively.

Conclusion: Zolbetuximab plus chemotherapy demonstrated favorable PFS and OS versus placebo plus chemotherapy in the Korean subgroup, with numerically greater efficacy compared with the overall pooled population. This may be potentially attributable to low rates of zolbetuximab discontinuation and toxicity management.

Keywords: Adenocarcinoma; Asia; Claudins; Drug therapy; Korea; Stomach neoplasms; Zolbetuximab.