A Study of GSK5764227 in Participants With Relapsed Small Cell Lung Cancer (SCLC)

Inclusion Criteria:

Participants are eligible to be included in the study only if all of the following criteria apply:

• Adults >18 or the minimum legal adult age at the time the informed consent form issigned

• Has histologically or cytologically confirmed extensive-stage small cell lung cancer (ES-SCLC).

• Has received 1 prior platinum-based systemic therapy with a PD- (L)1 inhibitor withat least 2 cycles of therapy and a chemotherapy free-interval of >30 days, withdocumented progression

• Has at least 1 target lesion per RECIST 1.1, as determined by the investigator.

• Is capable of giving signed informed consent, including compliance with therequirements and restrictions listed in the ICF and in the protocol.

• Has an ECOG performance status of 0 or 1

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• Pathological diagnosis of complex SCLC or transformed SCLC.

• Has received any prior therapy with an Antibody-drug conjugate (ADC) with aTopoisomerase-1 (TOPO1)-inhibitor payload or treatments targeting B7-H3.

• Has known sensitivity to study intervention components or excipients or otherallergy that, in the opinion of the investigator or medical monitor, contraindicatesparticipation in the study.

• Has severe, uncontrolled or active cardiovascular disorders.

• Has clinically significant bleeding symptoms or significant bleeding tendency within 1 month prior to the first dose.

• Known active infectious diseases requiring systemic treatment or known Humanimmunodeficiency virus (HIV).

• Has symptomatic brain metastases or untreated progression exclusively due to brainmetastasis during or after the last treatment prior to screening, evidence ofleptomeningeal/meningeal/brainstem metastasis or evidence of spinal cord metastases.

• Has any evidence of current interstitial lung disease or pneumonitis or a priorhistory of ILD or non-infectious pneumonitis requiring high dose steroids.

• Has documented Hepatitis B or Hepatitis C