A Study to Assess the Safety and Tolerability of BMS-986525 Alone and in Combination With Nivolumab in Participants With Relapsed/Refractory Small Cell Lung Cancer

Inclusion Criteria * Participants must have histologically or cytologically documented relapsed/refractory small cell lung cancer (R/R-SCLC). * Participants must have received at least 1 platinum-based chemotherapy regimen as per locally approved drug labels and institutional guidelines. * In countries where standard of care first line systemic treatment includes platinum containing chemotherapy in combination with anti-PD-(L)1 therapy, it is required that participants have progressed on, are ineligible for or not have access to an anti-PD- (L)1 therapy. Exclusion Criteria * Participants must not have any untreated CNS metastases. * Participants must not have an active, known or suspected autoimmune disease. * Participants must not have had a prior organ or tissue allograft. * Other protocol-defined Inclusion/Exclusion criteria apply.