In surprise move, Pfizer hands back IDO1 inhibitor
- Belgian biotech iTeos Therapeutics SA has regained all rights to its clinical stage IDO1 inhibitor, dubbed EOS200271, from big pharma licensee Pfizer Inc.
- The decision follows Pfizer's Phase 1 trial of the drug, which showed safety and brain penetration in patients with malignant gliomas, but found no efficacy. The study did not reach the maximum tolerated dose.
- iTeos is reviewing the data and plans to continue development of the treatment in oncology.
IDO1 inhibitors, which target an enzyme that modulates the immune response, have been lauded as another advance in immuno-oncology, with potential to boost the sometimes patchy response rates for PD-1/L1 inhibitors with less additional toxicity than CTLA4 inhibition.
The Pfizer deal was signed in 2014, and covered iTeos' IDO1 and TDO2 preclinical drug candidates. iTeos had an upfront payment of €24 million (around $28.9 million), with an equity investment, licensing fees and collaborative funding. It's not quite clear whether the entire deal is revoked, or just the IDO1 part, though no TDO2-based drugs appear in iTeos' pipeline. It's also not clear whether there will be any financial implications.
"IDO1 inhibitors are one of the most promising immuno-oncology drugs currently in development," said Michel Detheux, CEO of iTeos Therapeutics, taking an upbeat view. "This asset is one of four IDO1 inhibitors in clinical development worldwide and EOS200271 is the only IDO1 inhibitor with excellent brain penetration."
The news on other IDO1 inhibitors in development is currently mixed, and iTeos' announcement may not bode well for the field. Incyte Corp.'s epacadostat is in clinical studies as a combination therapy with Merck & Co.'s Keytruda (pembrolizumab) andAstraZeneca plc's Imfinzi (durvalumab) for a number of cancers. Incyte is also working with Bristol-Myers Squibb (Opdivo; nivolumab) and Roche. Positive results have sent the biotech's share price soaring.
NewLink Genetics Corp., another players in the IDO1 field, has released interim Phase 2 data that showed a 52% response rate for the combination of its indoximod with Keytruda in advanced melanoma, but this seemed to fall short of market expectations — pushing down NewLink's shares by almost 10% at the time.
Early data from a Phase 1b study of indoximod and Roche's Tecentriq (atezolizumab) in multiple advanced or metastatic tumors saw partial responses in just 9% of patients, though this was an early study in patients with serious disease.
- iTeos Therapeutics Press release
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