First-line immunotherapy approved for certain patients with colorectal cancer

The FDA on June 29 approved pembrolizumab (Keytruda) for IV injection for the first-line treatment of patients with unresectable or metastatic microsatellite instability-high or mismatch repair deficient colorectal cancer.

The medication, which targets the PD-1/PD-L1 pathway, is the first immunotherapy to be approved as a first-line treatment for this patient population without concomitant chemotherapy, the FDA said in a press announcement. It was previously approved to treat other types of cancer.

Approval was based on the results of one randomized trial comparing pembrolizumab with chemotherapy in 307 patients with microsatellite instability-high or mismatch repair deficient metastatic colorectal cancer. Median progression-free survival was 16.5 months in the pembrolizumab group and 8.2 months in the standard-of-care group, although longer-term analysis is needed to assess for an effect on survival.

Common side effects include fatigue, musculoskeletal pain, decreased appetite, pruritus, diarrhea, nausea, rash, fever, cough, dyspnea, constipation, pain, and abdominal pain. The drug can cause also cause immune-mediated side effects, including pneumonitis, colitis, hepatitis, endocrinopathies, and nephritis. Patients who experience severe or life-threatening infusion-related reactions should stop taking the drug.