On October 16, 2023, the FDA approved a new indication for pembrolizumab (Keytruda; Merck), a PD-1 inhibitor, combined with platinum-containing chemotherapy as neoadjuvant treatment, and with continuation of single-agent pembrolizumab as postsurgical adjuvant treatment for resectable (tumors ≥4 cm or node positive) non–small cell lung cancer (NSCLC).
Pembrolizumab monotherapy was previously approved for the adjuvant treatment of patients with stage IB (T2a ≥4 cm), II, or IIIA NSCLC, after resection and platinum-based chemotherapy as first-line treatment, as well as in patients with NSCLC and PD-L1 expression without ALK or EGFR mutations, and for patients with metastatic NSCLC and PD-L1 expression, after platinum-based chemotherapy. Pembrolizumab also has indications for the treatment of several other cancer types.
This approval of pembrolizumab was supported by the efficacy findings of the KEYNOTE671 trial (NCT03425643), a multicenter, randomized, double-blind, placebo-controlled clinical study of 797 patients with previously untreated and resectable stage II, IIIA, or IIIB (N2) NSCLC by the American Joint Committee on Cancer Cancer Staging Manual, 8th Edition. The patients were randomized to pembrolizumab or to placebo, with platinum-based chemotherapy, every 3 weeks for 4 cycles (neoadjuvant treatment) followed by continued single-agent pembrolizumab or placebo every 3 weeks for up to 13 cycles (adjuvant treatment).
The primary efficacy measures were overall survival (OS) and investigator-assessed event-free survival (EFS). The median OS was not reached in the pembrolizumab arm (95% confidence interval [CI], not estimable-not estimable) and was 52.4 months for patients who received placebo (95% CI, 45.7-not estimable; hazard ratio [HR], 0.72 [95% CI, 0.56-0.93]; P=.0103). The median EFS was not reached in the pembrolizumab arm (95% CI, 34.1-not estimable) and was 17 months in the placebo arm (95% CI, 14.3-22; HR, 0.58 [95% CI, 0.46-0.72]; P<.0001).
“There remains a need for treatment options to improve outcomes for patients with earlier stages of NSCLC. This important milestone has the potential to change the current treatment paradigm for resectable NSCLC that is >4 cm or has lymph node involvement, by offering an immunotherapy-based regimen that has demonstrated statistically significant improvements in OS and EFS compared to a placebo and chemotherapy regimen,” stated Heather Wakelee, MD, Principal Investigator for KEYNOTE671, thoracic medical oncologist, and Professor of Medicine at Stanford University, in a press release.
The most common (≥20%) adverse events with pembrolizumab treatment in KEYNOTE671 were nausea, fatigue, neutropenia, anemia, constipation, decreased appetite, a decrease in white blood cell count, musculoskeletal pain, rash, cough, vomiting, diarrhea, and dyspnea. Among the patients who received neoadjuvant pembrolizumab, 6% were unable to receive surgery as a result of adverse events compared with 4.3% in the placebo arm. Among the patients who received neoadjuvant treatment and surgery in the pembrolizumab arm, 3.1% had delays in surgery as a result of adverse events compared with 2.5% in the placebo arm.
The recommended dose of pembrolizumab is 200 mg every 3 weeks or 400 mg every 6 weeks. Pembrolizumab should be administered before chemotherapy when both treatments are administered on the same day.