Efficacy and Safety of Pembrolizumab Plus Docetaxel vs Docetaxel Alone in Patients With Previously Treated Advanced Non-Small Cell Lung Cancer: The PROLUNG Phase 2 Randomized Clinical Trial.

IMPORTANCE: Because of socioeconomic factors, many patients with advanced non-small cell lung cancer (NSCLC) do not receive immunotherapy in the first-line setting. It is unknown if the combination of immunotherapy with chemotherapy can provide clinical benefits in immunotherapy-naive patients with disease progression after treatment with platinum-based chemotherapy. OBJECTIVE: To evaluate the safety and efficacy of the combination of pembrolizumab plus docetaxel in patients with previously treated advanced NSCLC following platinum-based chemotherapy regardless of EGFR variants or programmed cell death ligand 1 status. DESIGN, SETTING, AND PARTICIPANTS: The Pembrolizumab Plus Docetaxel for Advanced Non-Small Cell Lung Cancer (PROLUNG) trial randomized 78 patients with histologically confirmed advanced NSCLC in a 1:1 ratio to receive either pembrolizumab plus docetaxel or docetaxel alone from December 2016 through May 2019. INTERVENTIONS: The experimental arm received docetaxel on day 1 (75 mg/m2) plus pembrolizumab on day 8 (200 mg) every 3 weeks for up to 6 cycles followed by pembrolizumab maintenance until progression or unacceptable toxic effects. The control arm received docetaxel monotherapy. MAIN OUTCOMES AND MEASURES: The primary end point was overall response rate (ORR). Secondary end points included progression-free survival (PFS), overall survival, and safety. RESULTS: Among 78 recruited patients, 32 (41%) were men, 34 (44%) were never smokers, and 25 (32%) had an EGFR/ALK alteration. Forty patients were allocated to receive pembrolizumab plus docetaxel, and 38 were allocated to receive docetaxel. A statistically significant difference in ORR, assessed by an independent reviewer, was found in patients receiving pembrolizumab plus docetaxel vs patients receiving docetaxel (42.5% vs 15.8%; odds ratio, 3.94; 95% CI, 1.34-11.54; P = .01). Patients without EGFR variations had a considerable difference in ORR of 35.7% vs 12.0% (P = .06), whereas patients with EGFR variations had an ORR of 58.3% vs 23.1% (P = .14). Overall, PFS was longer in patients who received pembrolizumab plus docetaxel (9.5 months; 95% CI, 4.2-not reached) than in patients who received docetaxel (3.9 months; 95% CI, 3.2-5.7) (hazard ratio, 0.24; 95% CI, 0.13-0.46; P < .001). For patients without variations, PFS was 9.5 months (95% CI, 3.9-not reached) vs 4.1 months (95% CI, 3.5-5.3) (P < .001), whereas in patients with EGFR variations, PFS was 6.8 months (95% CI, 6.2-not reached) vs 3.5 months (95% CI, 2.3-6.2) (P = .04). In terms of safety, 23% (9 of 40) vs 5% (2 of 38) of patients experienced grade 1 to 2 pneumonitis in the pembrolizumab plus docetaxel and docetaxel arms, respectively (P = .03), while 28% (11 of 40) vs 3% (1 of 38) experienced any-grade hypothyroidism (P = .002). No new safety signals were identified. CONCLUSIONS AND RELEVANCE: In this phase 2 study, the combination of pembrolizumab plus docetaxel was well tolerated and substantially improved ORR and PFS in patients with advanced NSCLC who had previous progression after platinum-based chemotherapy, including NSCLC with EGFR variations. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02574598.