Adjuvant Pembrolizumab Gets FDA Approval in NSCLC


Pembrolizumab has been approved by the FDA as an adjuvant treatment for patients with stage IB, II, or IIIA following resection and platinum-based chemotherapy.

The FDA has approved pembrolizumab (Keytruda) for the adjuvant treatment of patients with completely resected stage IB (T2a ≥ 4 cm diameter), II, or IIIA non–small cell lung cancer (NSCLC) following platinum-based chemotherapy. The approval is based on data from the KEYNOTE-091 trial (NCT02504372).1

Findings from the trial showed that treatment with pembrolizumab (n = 580) reduced the risk of disease symptom development by 27% compared with placebo (n = 581). The median disease-free survival (DFS) was 58.7 months (95% CI, 39.2-not reached [NR]) vs 34.9 months (95% CI, 28.6-NR) for pembrolizumab vs placebo, respectively (HR, 0.73; 95% CI, 0.60-0.89).1

The label comes with a warning for immune-mediated pneumonitis, which was reported in 41 patients (7%) treated with pembrolizumab in KEYNOTE-091 with 26 patients discontinuing treatment. Events were fatal (0.2%), grade 4 (0.3%), and grade 3 (1%) in nature. Patients who developed symptoms were treated with high-dose corticosteroids for a median duration of 10 days (range, 1 day to 2.3 months). Dose interruptions were reported for 54% of patients receiving pembrolizumab, 63% discontinued treatment, and 71% resolved symptoms.2

The label notes that other adverse events (AEs) observed in KEYNOTE-091 were consistent with previously reported data for patients with NSCLC receiving pembrolizumab. However, rates of hypothyroidism were higher at 22%.2 Additional AEs of note in the study were hyperthyroidism (11%), and pneumonitis (7%) with pembrolizumab.2

KEYNOTE-091 enrolled patients with stage IB/II-IIIA NSCLC who have undergone complete resection of either lobectomy or pneumonectomy with or without adjuvant chemotherapy. Individuals were randomly assigned to receive pembrolizumab 200 mg or placebo intravenously every 3 weeks for up to 1 year. The primary outcome was DFS with secondary end points of overall survival and lung cancer specific survival.3

The median age of patients who received adjuvant treatment following resection and chemotherapy was 64 years (range, 35-84), and 49% were 65 years or older. Among the overall populations 68% were men, 77% were White, 18% were Asian, and 86% were current or former smokers.2

In terms of disease stage, 11% of patients had stage IB, 57% had stage II, and 31% had stage IIIA disease. Tumor proportion score (TPS) was reported as follows: 39% had PD-L1 TPS lower than 1%; 33% had TPS 1% to 49%, and 28% had TPS at least 50%.2

The median duration of exposure to pembrolizumab was 11.7 months with 68% of patients in the pembrolizumab arm exposed to the agent for at least 6 months.2 Investigators performed an exploratory subgroup analysis of patients who did receive adjuvant chemotherapy (n = 167); the HR for DFS was 1.25 (95% CI, 0.76-2.05).1

Data reported from KEYNOTE-091 reported during a 2022 ESMO Plenary session showed that among allcomers DFS met the primary end point of the study, but was not statistically significant among patients with a TPS of at least 50%.


  1. FDA approves pembrolizumab as adjuvant treatment for non-small cell lung cancer. FDA. January 26, 2023. Accessed January 26, 2023.
  2. Keytruda. Prescribing information. Merck; 2023. Accessed January 26, 2023.
  3. Study of pembrolizumab (MK-3475) vs placebo for participants with non-small cell lung cancer after resection with or without standard adjuvant therapy (MK-3475-091/KEYNOTE-091) (PEARLS). Updated July 17, 2020. Accessed January 26, 2023.
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