Xilio and Merck Partner on Anti-CTLA-4 Antibody/Keytruda Combo in Solid Tumors


In preclinical studies, Xilio Therapeutics' tumor-selective anti-CTLA-4 antibody, dubbed XTX101, reaped positive results. In combination with anti-PD-1, it increased tumor growth inhibition without increased toxicity in vivo.

Now, Xilio is collaborating with Merck to evaluate XTX101 with Merck's Keytruda (pembrolizumab), a programmed death receptor-1 (anti-PD-1) therapy. The clinical trial, which will be conducted by Xilio, will assess XTX101's safety and efficacy as a monotherapy, as well as in combination with Keytruda, in solid tumors.

The clinical benefit of targeting CTLA-4 as a treatment for cancer is well-established. However, treatment with the combination of an anti-CTLA-4 mAb and PD-1 checkpoint inhibitor has been associated with challenging toxicities, preventing patients from receiving effective doses of the anti-CTLA-4 antibody,” said Marty Huber, M.D., chief medical officer of Xilio Therapeutics. “XTX101 is designed to be tumor-selective and based on data observed in preclinical studies, we believe it could be an ideal CTLA-4-targeting candidate to combine with checkpoint inhibitors like KEYTRUDA.”

In a previous announcement, Xilio said it plans to submit an investigational new drug (IND) application for XTX101 in the second quarter of 2021. The planned Phase I clinical trial would be initiated soon after the U.S. Food and Drug (FDA)’s clearance of the IND if things go as planned.

Xilio's other lead candidate, XTX202, a tumor-selective IL-2, has also seen some positive results in the clinic.

Preclinical data for XTX202 showed that it exhibited "tumor-selective activity in mice without peripheral toxicities in non-human primates."

Back in February, Xilio raised $95 million in a Series C round, which will be used to advance both XTX101 and XTX202 into the clinic.

The financing round was led by Rock Springs Capital, and was joined by Bain Capital Life Sciences, Deerfield Management Company, RA Capital Management and new and existing investors.

In other news, Pieris Pharmaceuticals and Genentech, a Roche company, also announced a research collaboration today.

The two companies entered a multi-program research collaboration and license agreement. The initial agreement includes respiratory disease and ophthalmology programs, with the possibility of additional programs.

As part of the deal, Pieris will receive $20 million upfront, and is eligible for more than $1.4 billion in additional milestone payments and royalties for commercialized programs.

"This is our second respiratory alliance with a major biopharma company, and we remain deeply committed to inhaled biologics, which have already shown benefit in the clinic,” said Stephen S. Yoder, President and Chief Executive Officer of Pieris. “We also look forward to pursuing another local application of our technology in ophthalmology, where Genentech has extensive capabilities.”

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