Antibody-Drug Conjugate Cuts Death Risk by 54% in Relapsed Small-Cell Lung Cancer

Patients with relapsed small-cell lung cancer may gain a powerful new second-line option, according to phase III results from the TAISHAN-302 trial presented at the International Association for the Study of Lung Cancer 2026 World Conference on Lung Cancer in Seoul. The study found that tambotatug pelitecan, known as Tam-Peli or YL201, a novel antibody-drug conjugate targeting the protein B7-H3, significantly improved overall survival, progression-free survival and objective response rate compared with topotecan, the long-standing standard second-line treatment for this disease. Relapsed small-cell lung cancer remains highly aggressive, with poor outcomes after first-line immunotherapy and platinum-based chemotherapy, and topotecan’s survival benefit has remained modest.

The randomized, open-label trial enrolled 451 patients whose small-cell lung cancer had relapsed after first-line therapy. Of these, 225 were assigned to Tam-Peli and 226 to topotecan. Patients in the experimental arm received 2.0 mg/kg of the antibody-drug conjugate 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 served as 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 reached 13.3 months with Tam-Peli compared with 9.4 months with topotecan. The antibody-drug conjugate reduced the risk of death by 54 percent, with a hazard ratio of 0.46 and a 95 percent confidence interval of 0.35 to 0.62, and a p-value below 0.0001. The survival benefit was consistent across prespecified subgroups, including patients with brain metastases, patients with liver metastases, and patients whose chemotherapy-free interval was less than 90 days, a group that typically faces particularly limited options.

The gains extended beyond survival. Median progression-free survival was 7.4 months with Tam-Peli versus 2.8 months with topotecan, corresponding to a 71 percent reduction in the risk of disease progression or death, with a hazard ratio of 0.29 and a 95 percent confidence interval of 0.23 to 0.37. The objective response rate, a measure of measurable tumor shrinkage, was 59.1 percent in the Tam-Peli arm compared with 9.7 percent in the topotecan arm, a difference that was also statistically significant.

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 percent of patients receiving Tam-Peli compared with 74.7 percent of those receiving topotecan, and there were no treatment-related deaths in the Tam-Peli arm. Treatment-emergent interstitial lung disease or pneumonitis, a class of toxicity watched closely with antibody-drug conjugates, occurred in 4.9 percent of patients on Tam-Peli and 1.4 percent on topotecan; grade 3 events occurred in 0.9 percent 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, who presented the findings, described the trial as a milestone for the drug class. “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,” she said. “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.”

The result is notable because small-cell lung cancer has proven stubbornly resistant to therapeutic progress. The disease accounts for a particularly lethal share of lung cancers, and treatment for patients whose tumors progress after first-line immunotherapy and platinum chemotherapy has changed little in years, leaving topotecan as the backbone of second-line care despite its limited survival benefit. Antibody-drug conjugates are designed to combine the targeting specificity of antibodies with the cell-killing potency of chemotherapy payloads, and B7-H3, the target of Tam-Peli, is a protein expressed on many solid tumors that has emerged as a focus of drug development.

Because the trial was open-label, both patients and investigators knew which treatment was assigned, a design feature that can influence the assessment of some outcomes, although objective endpoints such as overall survival are less susceptible to such bias. The findings were presented at a scientific conference and, as is standard for meeting presentations, will be subject to peer review when published in full. The results apply to the population studied, namely adults with relapsed small-cell lung cancer after first-line therapy, and longer follow-up will help clarify the durability of the survival benefit.

For now, the TAISHAN-302 results stand as a rare positive phase III readout in a disease with few recent wins, and they position an anti-B7-H3 antibody-drug conjugate as a candidate to displace a chemotherapy standard that has gone unchallenged for years in the second-line setting.

Subject of Research: A phase III trial of the anti-B7-H3 antibody-drug conjugate Tam-Peli versus topotecan in relapsed small-cell lung cancer

Article Title: Phase III TAISHAN-302 trial shows Tam-Peli significantly improves survival in relapsed small-cell lung cancer

Article References: Phase III TAISHAN-302 trial shows Tam-Peli significantly improves survival in relapsed small-cell lung cancer. Original publication (Bibliographic details unavailable.)

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Keywords: small-cell lung cancer, TAISHAN-302, Tam-Peli, YL201, B7-H3, antibody-drug conjugate, topotecan, overall survival, progression-free survival, phase III trial, second-line treatment, IASLC WCLC 2026