Is it Time Yet for Adjuvant Immunotherapy for Patients with DNA Mismatch Repair Deficient Gastric Cancer?

Excerpt

Gastric adenocarcinoma is a tremendous global health problem with more than a million patients diagnosed worldwide in 2020 and more than 768,000 gastric cancer-related deaths.¹ For patients with localized disease, surgical resection is critical but is not enough. Several studies over the past decades have indicated a role for adjuvant chemoradiation, adjuvant chemotherapy, or perioperative chemotherapy. For patients who do not receive any element of neoadjuvant therapy and who undergo a D2 lymphadenectomy during their surgery, adjuvant therapy with either S-1 or capecitabine and oxaliplatin chemotherapy are the treatment standards. In the phase III ACTS-GC trial, 1 year of adjuvant S-1 chemotherapy following gastrectomy inclusive of a D2 lymph node dissection was compared with surgery alone.² A total of 1,059 patients participated in this trial where the 5-year overall survival rate of those receiving S-1 was superior to those undergoing surgery alone (71.7% vs. 61.1%, hazard ratio [HR] 0.669), making adjuvant S-1 use a treatment standard in the Asian countries.^2,3 In the phase III CLASSIC trial, 1,035 patients with localized stage II-IIIB gastric cancer were randomized to undergo gastrectomy with a D2 lymph node dissection versus the same plus 6 months of capecitabine and oxaliplatin chemotherapy.⁴ This study demonstrated a significant improvement in 3-year, disease-free survival at 74% versus 59% in the surgery-alone group (HR 0.56, p < 0.0001), making adjuvant capecitabine and oxaliplatin an alternative adjuvant treatment standard. …