Roche's B7-H3 ADC Tam-Peli Cuts Death Risk 54% in Phase 3 Relapsed Small-Cell Lung Cancer Trial

Roche's collaborator MediLink Therapeutics released interim results from the randomized Phase III TAISHAN-302 trial evaluating tambotatug pelitecan (Tam-Peli, also known as YL201) against topotecan chemotherapy in 451 Chinese patients with relapsed small-cell lung cancer (SCLC) who had progressed after one prior line of platinum-based chemotherapy, with or without a PD-L1 inhibitor.¹ The trial met its primary endpoint of overall survival (OS), with Tam-Peli reducing risk of death by 54% (median OS 13.3 months versus 9.4 months; hazard ratio 0.46; p<0.0001).¹ Progression-free survival nearly tripled (7.4 months versus 2.8 months; hazard ratio 0.29; p<0.0001), and the confirmed objective response rate was 59.1% versus 9.7% for topotecan.¹ Benefit held consistently across prespecified subgroups, including patients with baseline brain metastases, where Tam-Peli extended median intracranial progression-free survival to 6.1 months versus 4.2 months and achieved a 32.4% intracranial response rate versus 2.9%.¹

Levi Garraway, M.D., Ph.D., Roche's chief medical officer and head of global product development, said, "The second positive phase III trial for Tam-Peli, TAISHAN-302, reinforces our confidence in its potential to improve outcomes for people with cancer. These data demonstrate clinically meaningful survival and response rate improvements in an aggressive and hard-to-treat disease, supporting our plans to initiate global phase III trials quickly."¹ Results are being presented as a Presidential Late-Breaking Abstract at the International Association for the Study of Lung Cancer's 2026 World Conference on Lung Cancer in Seoul, with simultaneous publication in The New England Journal of Medicine.¹ China's National Medical Products Administration has already accepted the New Drug Application for filing.¹

How does Tam-Peli work?

Tam-Peli is an antibody-drug conjugate (ADC) targeting B7-H3, a protein broadly expressed across solid tumors, including on tumor cells and within the tumor microenvironment, while showing limited expression in healthy tissue.¹ Built on MediLink's proprietary TMALIN (Tumor Microenvironment-Activatable Linker) platform, the ADC links a B7-H3-specific monoclonal antibody to a topoisomerase 1 inhibitor payload at a drug-to-antibody ratio of eight, using a stable, hydrophilic linker with a dual-release mechanism designed to deliver its cytotoxic payload both inside tumor cells and extracellularly within the tumor microenvironment.¹ Roche said the safety profile was favorable and manageable, with lower rates of Grade 3 or higher treatment-related adverse events compared with topotecan (46.4% versus 74.7%); treatment-emergent interstitial lung disease of any grade occurred in 4.9% of Tam-Peli patients versus 1.4% with topotecan, with low and comparable rates of Grade 3 events (0.9% in each arm) and no Grade 4 or 5 events reported.¹

Roche licensed worldwide rights to Tam-Peli outside mainland China, Hong Kong, and Macau from MediLink Therapeutics in January 2026, and is advancing the asset across multiple solid tumor types beyond SCLC, where it also holds two FDA Orphan Drug Designations and three China Breakthrough Therapy Designations, including for nasopharyngeal carcinoma, esophageal squamous cell carcinoma, and pancreatic cancer.¹

How crowded is the B7-H3 field in SCLC right now?

Tam-Peli's data lands in an unusually crowded moment for B7-H3-targeted therapy in SCLC. Just days earlier, GSK's licensing partner Hansoh Pharma reported positive phase 3 results for risvutatug rezetecan (Ris-Rez), another B7-H3-targeted ADC, in a similarly sized 461-patient trial in relapsed SCLC — meaning two separately developed, differently licensed B7-H3 ADCs posted positive late-stage SCLC survival data within the same week.² A third B7-H3-directed ADC, Daiichi Sankyo and Merck's ifinatamab deruxtecan, holds FDA priority review for the same relapsed SCLC setting, with a Prescription Drug User Fee Act target action date of October 10, 2026, based on Phase 2 data showing a 48.2% objective response rate.³ No B7-H3-directed therapy has yet received regulatory approval anywhere.³

That crowding extends beyond a single target. Amgen's tarlatamab (Imdelltra), a DLL3-targeted bispecific T-cell engager, remains the approved benchmark in the same post-platinum relapsed SCLC setting, having extended median overall survival to 13.6 months versus 8.3 months with chemotherapy in its own pivotal trial — figures broadly comparable to Tam-Peli's 13.3-month median OS, though the two trials enrolled different patient populations and cannot be directly cross-compared. A recent review of ADCs in SCLC noted that topoisomerase 1 inhibitor payloads specifically — the same payload class used in Tam-Peli — have generated the most consistent activity across the DLL3, TROP2, B7-H3, and SEZ6 targets under active clinical investigation in the disease, while microtubule-disrupting and pyrrolobenzodiazepine-based payloads have not demonstrated durable benefit.⁴

Tolerability is increasingly the axis on which competing ADCs in the same indication differentiate themselves. Sabeen Mekan, MD, chief medical officer at Zymeworks, addressed this directly in a panel discussion with BioPharm International® at the 2026 BIO International Convention: "We are getting to a point where safety is becoming much, much more important than it used to be. Patients want that, they deserve that. Clinicians are choosing those ADCs as well."⁶ Roche's own emphasis on Tam-Peli's lower rate of Grade 3 or higher treatment-related adverse events relative to chemotherapy, alongside its comparatively low rate of severe interstitial lung disease, reflects that same competitive dynamic playing out among ADCs vying for the same relapsed SCLC population.

Why does relapsed SCLC remain such a high-need setting?

SCLC accounts for roughly 15% of the 1.8 million annual lung cancer deaths worldwide and is characterized by rapid, aggressive progression regardless of stage at diagnosis.¹ Despite advances in first-line chemoimmunotherapy, relapse is nearly universal, and outcomes for recurrent disease have historically remained poor, a gap that has driven the current wave of ADC and bispecific antibody development targeting the disease.⁵

What happens next?

Roche plans to rapidly initiate global phase 3 trials for Tam-Peli beyond the China-based TAISHAN-302 population.¹

References

1. F. Hoffmann-La Roche Ltd. Roche's Collaborator MediLink Announces Phase III Data for Tam-Peli Showing Significantly Improved Overall Survival in Chinese Patient Population with Relapsed Small-Cell Lung Cancer. Press release. Published September 13, 2026. Accessed September 14, 2026.
2. Mirasol F. Regulatory Momentum Builds for ADCs in Solid Tumor Oncology. BioPharm International. Published March 24, 2026. Accessed September 14, 2026.
3. Schoenthaler E. Ifinatamab Deruxtecan Granted Priority Review for Previously Treated Extensive-Stage Small Cell Lung Cancer. BioPharm International. Published April 14, 2026. Accessed September 14, 2026.
4. Belluomini L, Sposito M, Avancini A, et al. Unlocking New Horizons in Small-Cell Lung Cancer Treatment: The Onset of Antibody–Drug Conjugates. Cancers. 2023;15(22):5368. doi:10.3390/cancers15225368.
5. Rudin CM, Brambilla E, Faivre-Finn C, Sage J. Small-Cell Lung Cancer. Nat Rev Dis Primers. 2021;7(1):3. doi:10.1038/s41572-020-00235-0.
6. Schoenthaler E, Mekan S. Novel Payloads and Multispecific Antibodies Fuel ADC Innovation. BioPharm International. Published June 25, 2026. Accessed September 14, 2026.