Adding Sugemalimab to CAPOX Improves Outcomes in Gastric/GEJ Adenocarcinoma

Adding sugemalimab to capecitabine plus oxaliplatin (CAPOX) improves outcomes in patients with previously untreated, advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma, according to study results presented at the ESMO Congress 2023.

Patients who received sugemalimab plus CAPOX had better overall survival (OS), progression-free survival (PFS), and overall response rates than patients who received CAPOX alone, reported study presenter Xiaotian Zhang, MD, of Beijing Cancer Hospital in China.

These results come from the phase 3 GEMSTONE-303 trial (ClinicalTrials.gov Identifier: NCT03802591). The trial enrolled 479 patients with previously untreated, unresectable, locally advanced or metastatic gastric/GEJ adenocarcinoma with PD-L1 expression of at least 5%.

The patients were randomly assigned to receive sugemalimab at 1200 mg every 3 weeks plus CAPOX (n=241) or placebo plus CAPOX (n=238). They were treated until disease progression, unacceptable toxicity, consent withdrawal, or the 2-year mark.

The median OS was 15.64 months in the sugemalimab arm and 12.65 months in the placebo arm (hazard ratio [HR], 0.75; 95% CI, 0.61-0.92; P =.0060). The 12-month OS rate was 61.25% in the sugemalimab arm and 52.02% in the placebo arm. The 24-month OS rate was 29.90% and 23.28%, respectively.

In the subset of patients who had PD-L1 expression of 10% or higher, the median OS was 17.81 months in the sugemalimab arm and 12.45 months in the placebo arm (HR, 0.64; 95% CI, 0.48-0.85). The 12-month OS rate was 63.83% in the sugemalimab arm and 52.59% in the placebo arm. The 24-month OS rate was 33.18% and 22.80%, respectively.

In the overall cohort, the median PFS was 7.62 months in the sugemalimab arm and 6.08 months in the placebo arm (HR, 0.66; 95% CI, 0.54-0.81; P <.0001). The 6-month PFS rate was 64.62% in the sugemalimab arm and 50.96% in the placebo arm. The 12-month PFS rate was 29.23% and 16.69%, respectively.

The overall response rate was 68.6% in the sugemalimab arm and 52.7% in the placebo arm. The rate of complete response was 1.4% and 1.0%, respectively. The median duration of response was 6.87 months and 4.63 months, respectively.

The rate of treatment-related adverse events (AEs) was 98.8% in the sugemalimab arm and 97.9% in the placebo arm. The rate of grade 3 or higher treatment-related AEs was 53.9% and 50.6%, respectively. Treatment-related AEs led to death for 2 patients in the sugemalimab arm and 3 patients in the placebo arm.

The most common treatment-emergent AEs of any cause in both arms were anemia, platelet count decrease, neutrophil count decrease, white blood cell count decrease, nausea, and vomiting.

AEs of special interest that were more common in the sugemalimab arm included hypothyroidism, hyperthyroidism, skin reactions, thyroiditis, colitis, diabetes mellitus, pneumonia, and hypophysitis.

Based on these results, Dr Zhang concluded that sugemalimab and CAPOX provides a new treatment option for gastric/GEJ adenocarcinoma in patients with PD-L1 expression of 5% or higher.

Disclosures: This research was supported by CStone Pharmaceuticals. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Zhang X, Wang J, Wang G, et al. GEMSTONE-303: Prespecified progression-free survival (PFS) and overall survival (OS) final analyses of a phase III study of sugemalimab plus chemotherapy vs placebo plus chemotherapy in treatment-naïve advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma. Presented at ESMO Congress 2023. Oct. 20-24, 2023. Madrid, Spain. Abstract LBA79.

This article originally appeared on Cancer Therapy Advisor