AACR21: iTeos busts out early human data for anti-TIGIT antibody. Is it enough to match up with Roche, Merck?
The TIGIT protein has turned into an arms race for Big Pharma, with Merck and Roche looking to add their own candidates to checkpoint inhibitor combos. A smaller player in that race, iTeos Therapeutics, is one step behind those big names and is rolling out early data that looks pretty par for the course.
iTeos’ anti-TIGIT immune receptor antibody EOS-448 posted one confirmed partial response and churned up no surprising safety signals in the dose-escalation, monotherapy portion of a Phase I/IIa study in patients with advanced solid tumors, according to data presented Saturday at the virtual AACR annual meeting.
One partial response isn’t enough to make investors eyes pop, but EOS-448’s results are pretty standard compared with its nearest competitors. Remember that Roche’s tiragolumab showed zero objective responses in its Phase Ia monotherapy study and just three across non-small cell lung cancer and head and neck squamous cell carcinoma in Phase Ib. Merck’s anti-TIGIT, MK-7684, showed just a single partial response in its monotherapy Phase I study, but ramped up quickly to eight partial responses as a combination with Keytruda.
There’s been a lot of focus on anti-TIGITs to show benefit as a monotherapy before combination studies with other immunotherapies given a high possibility of failure in late-stage studies, but all three of the major players in the race have focused far more on safety and tolerability early on than immediate biomarker efficacy.
As of December, iTeos’ study had enrolled 22 patients with no established standard of care and added an additional 11 to the study after the March 9 follow-up cutoff. The single partial response was in a melanoma patient who had stopped responding to Keytruda, and EOS-448 also showed disease stabilization in nine patients. Prior to March 9, a single serious treatment-related side effect was reported, a Grade 2 systemic inflammatory response. After March 9, two more serious TRAEs were reported, including a Grade 2 systemic inflammatory response and a Grade 3 infusion-related reaction.
iTeos was pleased enough with the results that it plans to expand enrollment in the Phase I/IIa to 40 patients. Meanwhile, the company is planning to enroll a suite of Phase Ib studies combining EOS-448 with Keytruda and iTeos’ own inupadenant for checkpoint-naive and and resistant patients with solid tumors, and as a monotherapy and combo with an immunomodulatory drug in multiple myeloma. The company will also conduct multiple Phase IIa studies in non-small cell lung cancer, head and neck cancer, melanoma and myeloma.
Social: Michel Detheux, iTeos CEO