Cel Sci Corporation (CVM)

[sab63090]

ESMO 2020/Merck

Merck's new immunotherapy target

Merck unveiled the first clinical data on a new type of antibody drug that targets myeloid cells, a type of immune cell that can suppress the immune system, limiting its ability to recognize and kill tumors.

Called MK-4830, the new but early-stage Merck drug represents a different approach to immunotherapy than its blockbuster product, Keytruda, which targets a protein called PD-1 found on T cells. MK-4830 blocks a protein called ILT4 found on myeloid cells, said Roy Baynes, Merck's chief medical officer.

In the Phase 1 study presented at ESMO today, which involved patients with a variety of solid tumors, the combination of MK-4830 and Keytruda showed partial tumor responses in eight of 34 patients, or 24%. Perhaps most intriguing, there were five responses in 11 patients with tumors that were no longer responsive to prior treatment with Keytruda alone. This suggests, but does not yet prove, that MK-4830 might benefit patients who are no longer helped by current immunotherapies.

Merck also tested MK-4830 alone, reporting a single response among 50 patients.

Half of the patients receiving MK-4830 alone or with Keytruda reported minor to moderate side effects, all consistent with what's typically seen with Keytruda. Merck tested escalating doses of MK-4830 in this early study, but did not see any side effects that would prevent higher doses from being tried in future studies that will target pancreatic cancer, brain cancer, head-and-neck cancer, lung cancer, and gastric cancer.

Jounce Therapeutics, a small biotech company, is also developing an anti-ILT4 cancer drug. Its Phase 1 study is expected to start later this year.