Massimo@Rainmaker1973
Scientists have discovered a promising new way to help the immune system detect and attack hidden cancer cells.
A first-in-class drug called GRWD5769 (an oral ERAP1 inhibitor) has shown encouraging early results, shrinking tumors in patients with six different types of advanced cancer: lung, liver, bladder, cervical, head and neck, and colorectal.
In a Phase 1/1b clinical trial (EMITT-1) involving 83 heavily pre-treated patients across multiple countries, tumors shrank in 26 participants. Of those, 15 experienced reductions of at least 30%. Many patients had already failed prior therapies, including immunotherapies.
The drug works by blocking the enzyme ERAP1, which cancers often use to “edit” their surface proteins and evade immune detection. By inhibiting ERAP1, GRWD5769 alters the tumor’s antigen presentation, effectively removing the cancer’s invisibility cloak and making the cells more visible to the immune system. It was tested in combination with the PD-1 inhibitor cemiplimab (Libtayo).
Particularly strong signals were seen in certain hard-to-treat cancers. For example, disease control for at least six months was achieved in 51% of colorectal cancer patients and 55% of lung cancer patients in the expansion cohorts.
While these early results are promising, experts emphasize this is still an early-phase study. Larger trials are needed to confirm efficacy, durability of response, and impact on long-term survival.
If successful, this approach could expand the number of patients who benefit from immunotherapy — which currently works in only about one-third of cases.
[Grey Wolf Therapeutics. “EMITT-1: Clinical and pharmacodynamic activity with the oral ERAP1 inhibitor GRWD5769 and cemiplimab in 6 completed phase 1b expansion cohorts in solid tumors...” Presented at ASCO Annual Meeting, 2026]
