A phase III trial evaluating the B7-H3 antibody-drug conjugate Tam-Peli in relapsed small-cell lung cancer reported a 54% reduction in the risk of death compared with topotecan. The TAISHAN-302 readout adds another late-line option for a disease area where post-platinum survival has historically been limited. The results underscore continuing clinical validation of next-generation ADCs in aggressive thoracic malignancies, particularly those with unmet needs after standard chemotherapy. The trial’s headline effect size will likely shape subsequent regulatory discussions and influence how clinicians sequence therapies after relapse. For investors and development teams, the key signal is not only efficacy, but the broader pattern of ADCs moving toward earlier consideration in refractory small-cell settings, tightening the competitive field around B7-H3-targeting payload strategies.