Merck ADC, licensed from China, hits mark in first big global trial

Dive Brief: An experimental antibody-drug conjugate Merck & Co. is developing with Kelun-Biotech succeeded in a global Phase 3 trial in endometrial cancer, helping treatment recipients live longer than those who got chemotherapy. The improvement in overall and progression-free survival was detected at an early, scheduled data check, Merck said Monday. The success in endometrial cancer follows by a few months positive results from a lung cancer trial Kelun conducted in China and that will be presented at the American Society of Clinical Oncology meeting later this month. Kelun has asked China’s drug regulator to approve use of the therapy in non-small cell lung cancer. The drug, called sacituzumab tirumotecan or Sac-TMT, is part of Merck’s strategy to sustain revenue growth once its top-selling cancer immunotherapy Keytruda loses patent protection later this decade. Merck aims to prove Sac-TMT can separate itself from Gilead Sciences’ Trodelvy and AstraZeneca and Daiichi Sankyo’s Datroway, both of which work similarly and are approved for certain breast and lung cancers. Dive Insight: Keytruda is one of the best-selling drugs of all time, an immunotherapy that proved effective in treating 19 different cancer types and won two additional “tissue-agnostic” clearances. Merck has acknowledged it won’t be able to replace Keytruda with a single medicine, and instead hopes an array of emerging treatments can help grow sales to $70 billion a year after its immunotherapy loses patent protection. Sac-TMT is among the drugs Merck is leaning on to achieve that goal. It’s one of many bets U.S. and European drugmakers recently made on medicines originating from Chinese laboratories, and is part of a wide-ranging alliance with Kelun that gave Merck rights to seven drug prospects. Sac-TMT delivers a toxic punch to tumors expressing TROP2, a protein found in many different cancers. Merck didn’t provide specifics in its Monday announcement. But it did disclose that Sac-TMT helped delay disease progression and extend lives when compared to treatment with one of two common chemotherapies. The drug was also associated with better remission rates. Enrollees in the trial had seen their cancer advance despite treatment with platinum-based chemo as well as Keytruda or other immunotherapies. The results were “statistically significant and clinically meaningful,” Merck said. The drug’s safety profile was also “consistent” with what’s been observed in earlier testing. The findings were the first from a broader development program evaluating Sac-TMT in 17 different tumor types, among them cancers of the breast and lungs. They provide “encouraging reinforcement of the safety profile for sac-TMT,” wrote RBC Capital Markets analyst Trung Huynh in a note to clients. The data being presented at ASCO, meanwhile, should offer “further clinical validation” for ongoing studies in lung cancer. Hyunh expects Sac-TMT to generate $2.6 billion in sales by 2030 and $7.2 billion by 2034.