The Food and Drug Administration has approved Tecentriq (atezolizumab), in combination with a fluoropyrimidine and oxaliplatin, as adjuvant treatment for stage III colon cancer with deficient DNA mismatch repair (dMMR), Roche announced October 9. The approval covers both the intravenous formulation and Tecentriq Hybreza, the subcutaneous co-formulation with hyaluronidase, and marks the twelfth US indication for the PD-L1 inhibitor. Roche describes it as the first approved immunotherapy-based regimen in this setting, and the company says it is pursuing regulatory filings with the European Medicines Agency to bring the regimen to patients outside the US.
The approval rests on the phase III ATOMIC trial, run by the Alliance for Clinical Trials in Oncology with sponsorship from the US National Cancer Institute. The study enrolled 712 patients with surgically removed stage III dMMR colon cancer that had spread to regional lymph nodes and randomized them to either mFOLFOX6 chemotherapy plus Tecentriq for six months followed by Tecentriq alone for six more months, or mFOLFOX6 alone. At a median follow-up of 40.9 months, the 3-year disease-free survival rate was 86.3 percent in the Tecentriq arm versus 76.2 percent with chemotherapy alone, translating to a 50 percent reduction in the risk of disease recurrence or death (hazard ratio 0.50, p = 0.0001). The benefit held across key subgroups including node stage, tumor stage and tumor location, and the results were published in the New England Journal of Medicine.
The clinical case is straightforward. Nearly one in four colon cancers is diagnosed at stage III, and despite surgery and chemotherapy, close to 30 percent of stage III patients experience recurrence within five years. Roughly 15 percent of colon cancers carry dMMR or microsatellite instability-high tumors, which indicate a higher mutation rate and a greater potential to respond to immunotherapy. “Until now, the adjuvant standard of care for stage III colon cancer has not differed based on mismatch repair status,” said Frank Sinicrope of the Mayo Clinic, the US principal investigator for ATOMIC, calling the regimen practice-changing.
For Roche, the approval extends Tecentriq’s reach at a moment when the adjuvant and early-stage settings have become the key battleground for checkpoint inhibitors: capturing a curative-intent indication secures treatment duration and physician habit before the franchise faces its next wave of competitive and pricing pressure. Genentech, which announced the approval on October 8, noted on the same day that eligibility depends on mismatch repair status determined by an immunohistochemistry test such as the Ventana MMR RxDx Panel.