The phase III TAISHAN-302 trial found that tambotatug pelitecan (Tam-Peli, YL201), a novel anti-B7-H3 antibody-drug conjugate, significantly improved overall survival, progression-free survival and objective response rate compared with topotecan in patients with relapsed small-cell lung cancer (SCLC). The findings were presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer (WCLC).
Relapsed SCLC remains a highly aggressive disease with limited effective treatment options and poor outcomes following first-line immunotherapy and platinum-based chemotherapy. Topotecan has long been a standard second-line treatment, but its survival benefit remains modest. TAISHAN-302 evaluated Tam-Peli as a second-line treatment for patients whose SCLC had relapsed after first-line therapy.
The randomized, open-label study enrolled 451 patients, with 225 assigned to Tam-Peli and 226 to topotecan. Patients receiving Tam-Peli were treated with 2.0 mg/kg intravenously on day 1 of each three-week cycle, with a maximum dose of 200 mg. Treatment continued until disease progression or unacceptable toxicity. The study's primary endpoint was overall survival, 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 compared with 9.4 months with topotecan. Tam-Peli reduced the risk of death by 54% (HR 0.46; 95% CI 0.35–0.62; p<0.0001). The survival benefit was consistent across prespecified subgroups, including patients with brain metastases, liver metastases and a chemotherapy-free interval of less than 90 days.
Tam-Peli also significantly improved progression-free survival. Median progression-free survival was 7.4 months with Tam-Peli versus 2.8 months with topotecan, representing 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 safety profile of Tam-Peli was considered manageable and consistent with its known profile, with no new safety signals identified. Grade 3 or higher treatment-related adverse events occurred in 46.4% of patients receiving Tam-Peli compared with 74.7% 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 receiving Tam-Peli and 1.4% receiving topotecan; grade 3 events occurred in 0.9% of patients in each group, with no grade 4 or 5 events reported.
TAISHAN-302 is among the first phase III studies of an antibody-drug conjugate to demonstrate 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. Together with a generally favorable and manageable safety profile, these results support Tam-Peli as a potential new standard-of-care option for second-line SCLC and may reshape the treatment landscape for this challenging disease."
Professor Li Zhang of Sun Yat-sen University Cancer Center
Study shows how the microbiome shapes lung cancer immunotherapy outcomes