ZL-1310 for Relapsed Small Cell Lung Cancer

Inclusion Criteria: * Age \>/= 18 years, or considered an adult by local regulations, at the time of consent * Signed informed consent * Histologically or cytologically confirmed SCLC. Received 1L platinum-based systemic therapy and had documented disease progression during or after the most recent systemic therapy. Or received 2L tarlatamab is allowed. * Measurable disease according to RECIST v1.1 as assessed by the investigator. * Participants with a history of treated and stable or untreated and asymptomatic CNS metastases based on criteria per protocol. * Adequate organ and marrow function * Eastern Cooperative Group (ECOG) performance status of 0 or 1 * Life expectancy of at least 3 months * Participants must be willing to undergo a tumor biopsy or provide archived tumor tissue sample at Screening * Participants must be willing and able to comply with protocol for the duration of the study Exclusion Criteria: * Received more than one line of systemic therapy for Extensive-Stage SCLC. * Received any prior ADC with topoisomerase 1 inhibitor payload * Participants with another known malignancy with exceptions defined in the protocol. * History or suspected ILD/pneumonitis based on criteria per protocol * Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses. * Receipt of anti-cancer treatment known to treat cancers within 3 weeks before the first dose of study treatment. * Prior radiotherapy before study treatment based on criteria per protocol * Unresolved toxicity of Grade \>/= 2 from previous anti-cancer treatment, except for alopecia and skin pigmentation. * Known infection or active infection defined in the protocol. * Clinically significant active cardiovascular disease or history of arterial thromboembolic event within 6 months prior to the first dose of study treatment based on criteria per protocol.