The phase III TAISHAN-302 trial found that tambotatug pelitecan (Tam-Peli, YL201), an anti-B7-H3 antibody-drug conjugate, improved overall survival, progression-free survival and objective response rate compared with topotecan in patients with relapsed small-cell lung cancer. The results were presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer, the association said.

According to the release, relapsed small-cell lung cancer remains an aggressive disease with limited effective treatment options and poor outcomes after first-line immunotherapy and platinum-based chemotherapy. Topotecan has long been a standard second-line treatment, but the release said its survival benefit remains modest. The randomized, open-label study enrolled 451 patients, assigning 225 to Tam-Peli and 226 to topotecan. Patients in the Tam-Peli arm received 2.0 mg/kg intravenously on day 1 of each three-week cycle, with a maximum dose of 200 mg, and treatment continued until disease progression or unacceptable toxicity. Overall survival was the primary endpoint, with progression-free survival and objective response rate as key secondary endpoints.

As of May 20, 2026, after a median follow-up of 9.4 months, median overall survival was 13.3 months with Tam-Peli and 9.4 months with topotecan. The trial reported a 54% reduction in the risk of death with Tam-Peli (HR 0.46; 95% CI 0.35–0.62; p < 0.0001), and the release said the survival benefit was consistent across prespecified subgroups, including patients with brain metastases, liver metastases and a chemotherapy-free interval of under 90 days. Median progression-free survival was 7.4 months with Tam-Peli versus 2.8 months with topotecan, a 71% reduction in the risk of disease progression or death (HR 0.29; 95% CI 0.23–0.37; p < 0.0001). The objective response rate was 59.1% with Tam-Peli compared with 9.7% with topotecan (p < 0.0001).

The trial reported that Tam-Peli's safety profile was manageable and consistent with its known profile, with no new safety signals. Grade 3 or higher treatment-related adverse events occurred in 46.4% of patients receiving Tam-Peli compared with 74.7% of those receiving topotecan, and there were no treatment-related deaths in the Tam-Peli arm. Treatment-emergent interstitial lung disease or pneumonitis occurred in 4.9% of patients on Tam-Peli and 1.4% on topotecan; grade 3 events occurred in 0.9% of patients in each group, with no grade 4 or 5 events reported.

Professor Li Zhang of Sun Yat-sen University Cancer Center in Guangzhou, China, said TAISHAN-302 was among the first phase III studies of an antibody-drug conjugate to show statistically significant and clinically meaningful improvements in overall survival, progression-free survival and objective response rate compared with topotecan in relapsed small-cell lung cancer. He said the results, together with a generally favorable and manageable safety profile, support Tam-Peli as a potential new standard-of-care option for second-line small-cell lung cancer.