GSK’s Hansoh-partnered ADC lays down marker for lung cancer scrap with Merck

Biotech GSK’s Hansoh-partnered ADC lays down marker for lung cancer scrap with Merck By Nick Paul Taylor Sep 12, 2026 7:00pm GSK Hansoh Pharma small cell lung cancer antibody-drug conjugates GSK’s risvutatug rezetecan (ris-rez) has achieved a median overall survival (OS) of 18.5 months in a phase 3 trial, painting the antibody-drug conjugate (ADC) as a threat to Amgen and Merck & Co. in the lung cancer field. The phase 3 trial, sponsored by GSK’s partner Hansoh Pharma, enrolled 461 small cell lung cancer (SCLC) patients at sites in China.

Participants, all of whom had relapsed after first-line platinum-based therapy, received the B7-H3-directed ADC ris-rez or the chemotherapy medicine topotecan intravenously every three weeks. Median OS was 18.5 months in the ris-rez cohort, compared to 10.3 months in the topotecan arm. The result was statistically significant, achieving the trial’s primary endpoint, and compares favorably to data on other second-line treatments for SCLC.

Amgen linked its DLL3xCD3 T-cell engager Imdelltra to a median OS of 13.6 months in a phase 3 trial, versus 8.3 months in people who received one of three chemotherapy drugs, including topotecan. Meanwhile, Merck and Daiichi Sankyo are seeking FDA approval for a B7-H3-directed ADC, ifinatamab deruxtecan (I-DXd), based on a phase 2 trial that reported a median OS of 12.0 months in second-line SCLC. Differences between the studies confound efforts to compare the data.

One obvious variation is that the ris-rez trial only worked with sites in China, while the studies of Imdelltra and I-DXd were global. As Western drugmakers have increasingly turned to China for new cancer drugs, uncertainty about whether clinical data generated in the country will translate to global studies has become a key question. Hesham Abdullah, M.D., global head of oncology, research and development at GSK, addressed the topic on a media call.

The consistency of Chinese and global data on mocertatug rezetecan, the B7-H4-directed ADC that GSK is developing with Hansoh, increases confidence that the ris-rez results can translate globally, Abdullah said. Chinese and global patients take similar drugs before trying ris-rez, he added. Given evidence of similar treatment pathways and outcomes, Abdullah framed parallel development of ris-rez in Hansoh’s Chinese trials and GSK’s global studies as an advantage.

GSK has near-real-time access to Hansoh’s results, giving it “two independent data sets that are being replicated” to inform decisions about which indications to prioritize, the executive said. GSK started a global phase 3 ris-rez trial in relapsed SCLC last year and expects to publish pivotal data in 2027. While this timeline puts GSK behind its rivals, Abdullah suggested safety could be a potential differentiator for ris-rez.

He noted that interstitial lung disease (ILD) is associated with some other platforms. Daiichi and Merck reported two fatal treatment-related ILD/pneumonitis events in their midphase I-DXd trial. Hansoh reported no grade 4 or 5 ILD events in its phase 3 trial.

Ris-rez is associated with the adverse event, with Hansoh reporting a similar proportion of grade 3 ILD events—3.9%—as Daiichi and Merck saw in their I-DXd study. Even so, the absence of fatal events in the Hansoh trial points to a possible edge for the GSK-partnered ADC. Evidence that ris-rez is differentiated could increase investor interest in an asset that has attracted little fanfare to date.

The differentiation of ris-rez is “unclear to us at the moment,” Guggenheim Securities analysts said in a July note to investors, adding that they ascribed limited risk-adjusted sales to the asset and the rest of GSK’s ADC portfolio. GSK Hansoh Pharma small cell lung cancer antibody-drug conjugates solid tumor Merck & Co. Daiichi Sankyo Amgen Biotech Clinical Data