BioNTech paid $200 million to share in the development of an immunotherapy with potential advantages over a blockbuster Bristol Myers Squibb product from the same drug class. Now the German company and partner OncoC4 are reporting the clinical data that led to the deal.

In Phase 1/2 results, treatment with the experimental BioNTech and OncoC4 drug, called gotistobart, was able to help patients whose metastatic non-small cell lung cancer (NSCLC) developed drug resistance. In results from 27 patients, treatment with gotistobart led to an overall response rate of 29.6%. The disease control rate was 70.4%, including one patient with a complete response, seven partial responses, and 11 with stable disease. These results were presented Friday during a poster session discussion during the annual meeting of the American Society of Clinical Oncology in Chicago.

Gotistobart is a type of cancer immunotherapy called a checkpoint inhibitor. The antibody is designed to block CTLA-4, a protein on immune cells that keeps the body’s immune responses in check. Blocking this protein frees the immune cells to go after and kill cancer cells. The Phase 1/2 study tested the OncoC4 drug as a monotherapy in patients whose cancer developed resistance to drugs that target other so-called checkpoint proteins, including one targeted by the blockbuster Merck immunotherapy Keytruda.

Rockville, Maryland-based OncoC4 describes gotistobart as a next-generation anti-CTLA-4 antibody. The drug targets regulatory T cells, or Tregs, a type of immune cell that tamps down the immune response. But by selectively targeting Tregs in the tumor microenvironment, OncoC4 says immune cells in healthy tissue are spared the drug’s effects. Consequently, the drug is intended reduce immune-related adverse effects—a common complication of cancer immunotherapies.

The first CTLA-4 inhibitor was BMS’s Yervoy, which was first approved in 2011 for treating melanoma. The drug has since won an additional approval in NSCLC among other types of cancer, but only when used in combination with another BMS drug, Opdivo. The only other CTLA-4 inhibitor on the market is AstraZeneca’s Imjudo, which last year won FDA approvals in liver cancer and NSCLC. But for those indications, Imjudo must be used in combination with another AstraZeneca immunotherapy, Imfinzi.

The partnered BioNTech and OncoC4 drug has the potential to stand apart as a monotherapy for cases of NSCLC that have developed resistance to other checkpoint inhibitors. Under the terms of the alliance struck up in March, the companies will share in the development of gotistobart as a monotherapy or as part of drug combinations for various solid tumors. A Phase 3 test of the drug as a monotherapy for patients with NSCLC is expected to begin in the third quarter of this year.

“Metastatic NSCLC has a very poor prognosis with a 5-year survival rate of only 9%,” Özlem Türeci, chief medical officer and BioNTech co-founder said in a prepared statement. “These new data highlight the potential of BNT316/ONC-392 to provide a new approach to leveraging CTLA-4 as an effective target to address advanced, hard-to-treat tumors, further broadening our oncology toolkit.”

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