FDA Approves Pembrolizumab for Tissue-Agnostic Indication

Pembrolizumab (Keytruda) has been granted an accelerated approval by the FDA for the treatment of adult and pediatric patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch fix deficient (dMMR) solid tumors that have progressed after prior treatment and who have no satisfactory alternative treatment options, as well as for patients with MSI-H or dMMR colorectal cancer following progression on a fluoropyrimidine, oxaliplatin, and irinotecan.

In its second approval in a week, the FDA OKs the use of the PD-1 inhibitor to treat adult and pediatric patients with unresectable or metastatic solid tumors that are have a genetic profile called microsatellite instability-high (MSI-H) or mismatch fix deficient (dMMR). The indication also includes patients with colorectal cancer (CRC) that is MSI-H or dMMR and who have progressed on fluoropyrimidine, oxaliplatin, and irinotecan.

According to FDA, MSI-H and dMMR tumors contain abnormalities that affect the proper fix of DNA and such tumors are most commonly found in colorectal, endometrial and gastrointestinal cancers, though also less commonly appear in breast, prostate, bladder, thyroid gland and other cancers.

Keytruda's other indications-in bladder cancer and lung cancer, for instance-depend upon the part of the body where a tumor originated. It also includes patients with colorectal cancer whose disease has advanced despite chemotherapy.

The approval marks the first time the USA health regulator has approved a cancer drug based on a biomarker - a biological signal that suggests an increased or decreased risk for a disease. The approval was based on data from 149 patients with MSI-H or dMMR cancers enrolled across 5 single-arm clinical trials. Further, 11 complete responses and 48 partial responses were documented.

The objective response rate was 39.6% (95% CI, 31.7 to 47.9) and the minimum duration of response was 6 months in 78% of patients who responded to the PD-1 inhibitor.

In its statement on the approval, the FDA listed common side effects of Keytruda, including fatigue, pruritus, diarrhea, decreased appetite, rash, pyrexia, cough, dyspnea, musculoskeletal pain, constipation and nausea. Keytruda can cause serious conditions known as immune-mediated side effects, including inflammation of healthy organs such as the lungs (pneumonitis), colon (colitis), liver (hepatitis), endocrine glands (endocrinopathies) and kidneys (nephritis). The safety and effectiveness of Keytruda in pediatric patients with MSI-H central nervous system cancers have not been established.

While many investors in drug stocks have been rattled by President Donald Trump's previous comments about such companies, shares of firms such as Merck & Co., Inc.

  • Zachary Reyes