The study included screening period, treatment period (including induction and maintenance), safety follow-up and survival follow-up periods.~Induction treatment will be administered on a Q3W cycle for 4 cycles.~Following induction treatment, patients who have received 4 cycles of tislelizumab and platinum-based chemotherapy and meet the following criteria will enter a maintenance treatment phase with tislelizumab and sitravatinib:~Patients have an ongoing response per RECIST v1.1 criteria of SD or better assessed by the investigator according to RECIST v1.1（Patients will be eligible to enter maintenance phase if chemotherapy interruption due to toxicity, but at least 3 cycles of tislelizumab combined with chemotherapy are completed and assessed as CR, PR or SD according to RECISTv1.1 criteria）.~Excluded patients with central cavitary ES-SCLC, or tumor invading or adjacent to large vessels as shown by imaging, and likely to invade large vessels and cause fatal bleeding assessed by the investigator.~During the maintenance treatment period prophylactic cranial irradiation (PCI) is permitted as per local standard of care.~Treatment may continue until 1) disease progression as assessed by the investigator per RECIST v1.1, 2) loss of clinical benefit as assessed by the investigator, 3) unacceptable toxicity, or 4) withdrawal of informed consent, whichever occurs first, 5) study treatment duration reached 2 years (including induction and maintenance period).~Per investigator's discretion, patients who may continue to benefit from study treatment after progressive disease must meet the following criteria in order to be treated and documented in the study records:~Absence of symptoms and signs indicating clinically significant progression of disease and absence of worsening of laboratory values indicating disease progression.~Stable ECOG performance status ≤ 1 Absence of rapid progression of disease or of progressive tumor at critical anatomical sites (eg,cord compression) that requires urgent alternative medical intervention Investigators must obtain written informed consent for treatment beyond radiologic disease.~Study treatment will be administered for up to 2 years (including induction and mantenance period).
This is an open-label, single-arm, prospective phase 2 study, evaluating the efficacy and safety of tislelizumab combined with sitravatinib as maintenance therapy following tislelizumab and chemotherapy for treatment naïve extensive stage small cell lung cancer.