Merck’s drug vibostolimab, when used alongside the company’s other immunotherapy Keytruda, produced better response rates than Keytruda has alone in ovarian and cervical tumors, Graybosch wrote in a note to clients. That finding suggests TIGIT drugs might broaden the reach of immunotherapies into tumors that are less responsive to those types of drugs.

The results were somewhat perplexing, however. The drug performed best in cervical cancer patients who had no PD-L1 on their tumors, as well as in ovarian cancer patients with high PD-L1 levels. Overall results were also comparable to what’s been observed in prior tests of Keytruda, raising questions of whether the subgroup findings were just statistical “noise,” Graybosch wrote.

More definitive answers about TIGIT’s potential in ovarian and cervical tumors will come when Roche delivers results from a Phase 2 trial called SKYSCRAPER-04 later this year. Data from a Phase 3 study in a common, more treatable form of lung cancer, meanwhile, are expected even sooner. Until then, Merck’s results “leave room for debate and doubt” about TIGIT, Graybosch wrote.

A solid tumor advance for CAR-T

Long before BioNTech developed one of the most widely used vaccines for COVID-19, the German biotech was focused on making cancer immunotherapies.

Over the weekend at AACR, that work was back in the spotlight as researchers presented study results for one of BioNTech’s experimental cancer medicines. The treatment consists of a CAR-T therapy made from patient immune cells, paired with an mRNA vaccine encoding for the same protein targeted by the cell therapy.

The combination approach is designed to help the cancer-fighting CAR-T cells expand and persist in the body after their infusion, and potentially solve a limitation that has prevented CAR-T therapies from successfully treating solid tissue tumors.

“Our preliminary data indicate that the successes of CAR-T in hematological cancers may indeed be transferred to solid tumors,” said BioNTech CEO Ugur Sahin, in a statement.

BioNTech’s data comes from 16 patients with cancers expressing a protein known as Claudin-6 that’s commonly found in testicular, ovarian and endometrial tumors.

Six of 14 evaluable patients responded to treatment, including one who went into remission. Four of those responses were in patients who received the CAR-T as well as the mRNA vaccine. (Some only received the CAR-T.)

The small number of patients involved and lack of a control arm means determining relative benefit is difficult, while limited follow-up makes judging the durability of treatment effect harder.

Side effects were common, although those typically associated with CAR-T treatment were classified as less severe and “manageable,” according to BioNTech. Two dose-limiting toxicities were reported, one of which occurred prior to administration of the mRNA vaccine.

Further data from the study will be presented later this year.