OBJECTIVES: The ECOG-ACRIN Cancer Research Group trial E2511 recently demonstrated a potential benefit for the addition of veliparib to cisplatin-etoposide (CE) in patients with extensive stage small cell lung cancer (ES-SCLC) in a phase II randomized controlled trial. Secondary trial endpoints included comparison of the incidence and severity of neurotoxicity, hypothesized to be lower in the veliparib arm, and tolerability of the addition of veliparib to CE. Physician-rated and patient-reported neurotoxicity was also compared. MATERIALS AND METHODS: Patients randomized to veliparib plus CE (n = 64) or placebo plus CE (n = 64) completed the 11-item Functional Assessment of Cancer Therapy Gynecologic Oncology Group Neurotoxicity (questionnaire pre-treatment, end of cycle 4 [ie 3 months after randomization] and 3 months post-treatment [ie 6-months]). Adherence analysis was based on treatment forms. RESULTS AND CONCLUSION: No significant differences in mean or magnitude of change in neurotoxicity scores were observed between treatment arms at any time point. However, patients in the placebo arm reported worsening neurotoxicity from baseline to 3-months (M difference = -1.5, P = .045), compared to stable neurotoxicity in the veliparib arm (M difference = -0.2, P = .778). Weakness was the most common treatment-emergent (>50%) and moderate to severe (>16%) symptom reported, but did not differ between treatment arms. The proportion of adherence to oral therapy in the overall sample was 75%. Three percent of patients reported clinically significant neurotoxicity that was not captured by physician assessment. Neurotoxicity scores were not different between treatment arms. The addition of veliparib to CE appeared tolerable, though weakness should be monitored. CLINICALTRIALS. GOV IDENTIFIER: NCT01642251.