Importance: Patients with relapsed small cell lung cancer (SCLC), a high replication stress tumor, have poor prognoses and few therapeutic options. A phase 2 study showed antitumor activity with the addition of the ataxia telangiectasia and Rad3-related kinase inhibitor berzosertib to topotecan.
Objective: To investigate whether the addition of berzosertib to topotecan improves clinical outcomes for patients with relapsed SCLC.
Design, setting, and participants: Between December 1, 2019, and December 31, 2022, this open-label phase 2 randomized clinical trial recruited 60 patients with SCLC and relapse after 1 or more prior therapies from 16 US cancer centers. Patients previously treated with topotecan were not eligible.
Interventions: Eligible patients were randomly assigned to receive topotecan alone (group 1), 1.25 mg/m2 intravenously on days 1 through 5, or with berzosertib (group 2), 210 mg/m2 intravenously on days 2 and 5, in 21-day cycles. Randomization was stratified by tumor sensitivity to first-line platinum-based chemotherapy.
Main outcomes and measures: The primary end point was progression-free survival (PFS) in the intention-to-treat population. Secondary end points included overall survival (OS) in the overall population and among patients with platinum-sensitive or platinum-resistant tumors. The PFS and OS for each treatment group were estimated using the Kaplan-Meier method. The log-rank test was used to compare PFS and OS between the 2 groups, and Cox proportional hazards models were used to estimate the treatment hazard ratios (HRs) and the corresponding 2-sided 95% CI.
Results: Of 60 patients (median [range] age, 59 [34-79] years; 33 [55%] male) included in this study, 20 were randomly assigned to receive topotecan alone and 40 to receive a combination of topotecan with berzosertib. After a median (IQR) follow-up of 21.3 (18.1-28.3) months, there was no difference in PFS between the 2 groups (median, 3.0 [95% CI, 1.2-5.1] months for group 1 vs 3.9 [95% CI, 2.8-4.6] months for group 2; HR, 0.80 [95% CI, 0.46-1.41]; P = .44). Overall survival was significantly longer with the combination therapy (5.4 [95% CI, 3.2-6.8] months vs 8.9 [95% CI, 4.8-11.4] months; HR, 0.53 [95% CI, 0.29-0.96], P = .03). Adverse event profiles were similar between the 2 groups (eg, grade 3 or 4 thrombocytopenia, 11 of 20 [55%] vs 20 of 40 [50%], and any grade nausea, 9 of 20 [45%] vs 14 of 40 [35%]).
Conclusions and relevance: In this randomized clinical trial, treatment with berzosertib plus topotecan did not improve PFS compared with topotecan therapy alone among patients with relapsed SCLC. However, the combination treatment significantly improved OS.
Trial registration: ClinicalTrials.gov Identifier: NCT03896503.