Dive Brief:

• Merck & Co.’s partner Kelun-Biotech said its experimental medicine sac-TMT helped patients with a form of lung cancer stave off disease progression better than a standard regimen including chemotherapy in a new Phase 3 study.
• The trial, conducted in China, included patients with locally advanced or metastastic non-squamous non-small cell lung cancer whose tumor cells don’t have enough of a protein called PD-L1. When working properly, PD-L1 helps the immune system focus on killing diseased cells instead of healthy ones. But too much or too little of this protein can throw the system off kilter.
• Kelun previously saw success with sac-TMT in PD-L1-positive patients and is now tackling the “negative” patients who represent what it calls a “therapeutic bottleneck.” Sac-TMT is the first so-called antibody drug conjugate to succeed in a Phase 3 study of this patient population in combination with an immunotherapy like Keytruda, Kelun said Tuesday.

Dive Insight:

Merck is betting big on sac-TMT and the larger class of antibody-drug conjugates. The New Jersey-based drugmaker struck a series of deals — potentially worth billions of dollars — with Kelun to develop sac-TMT and others in the class. It also invested $1 billion in ADC specialist Seagen and reportedly considered buying the company, which was eventually taken over by Pfizer.

ADCs offer a more targeted way to treat cancer, delivering a toxic payload directly to tumor cells instead of a blast of chemotherapy that can also kill healthy cells. AstraZeneca and Daiichi Sankyo have established their ADC Enhertu as a top seller in breast cancer. A range of companies, including Merck, are trying to replicate that success.

Kelun has already won approval in China to market sac-TMT for certain types of breast and lung cancers, encompassing four different indications. Merck, meanwhile, has 17 Phase 3 studies underway looking at how sac-TMT affects tumors in the breast, lung, and gastrointestinal and genitourinary systems, as well as gynecological cancers. One endometrial cancer trial succeeded in an early, scheduled data check announced in May.

The new data also come from a prespecified interim analysis. Kelun didn’t offer detailed results, but said the combination therapy that included its drug “demonstrated a statistically significant and clinically meaningful improvement” in progression-free survival compared with the chemotherapy regimen. An independent monitoring board also observed a “positive trend” in overall survival.

Because the latest study was only conducted in China, it doesn’t have an immediate global impact for Merck’s development of the drug, Leerink Partners analyst Daina Graybosch wrote in a note to clients. But it’s a groundbreaking proof-of-concept study for sac-TMT and builds on the medicine’s “strong clinical momentum,” Graybosch added.