Merck, Incyte chalk up promising melanoma data for Keytruda-epacadostat combo

Merck's Keytruda forms the PD-1 side of a combo regimen that also includes Incyte's experimental IDO1 inhibitor epacadostat.

MADRID, Spain—The true test of a new Keytruda combination—with Incyte’s IDO1 enzyme inhibitor epacadostat—won’t deliver its results till early next year. But in the meantime, Merck & Co. and Incyte unveiled data from a small, earlier-stage test, and it’s among the most closely monitored presentations at the European Society for Medical Oncology Congress this weekend.

Immuno-oncology watchers started parsing the data when abstracts were released at the end of August, and the details are finally here: 56% of melanoma patients treated with the combo responded to therapy, and continued to respond for a median 45 weeks. The pair also held off cancer progression for a median 12.4 months, the analysis found.

The combined phase 1/2 study, dubbed Echo-202, enrolled patients with a variety of cancers, and the companies reported positive results from the overall group at this year's American Society of Clinical Oncology meeting. This new analysis centered on a cohort with advanced melanoma who had not been previously treated with immunotherapy meds in the PD-1/L1 or CTLA4 classes.

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Thirty-five of the 63 patients evaluated saw benefits from the combo, and nine of them saw their cancers disappear after the therapy. Partial responses were seen in 26 patients, or 41%. Of those 35 who responded, 30 were still seeing benefits from the tandem treatment when this round of data was gathered.

“These results show that this combination has demonstrated increased and durable response rates and improved progression-free survival, compared to what we would expect from Keytruda alone, without sacrificing safety,” according to trial investigator Omid Hamid, M.D., chief of translational research and immuno-Oncology and director of melanoma therapeutics at The Angeles Clinic and Research Institute.

Though the response rates are lower than those released in a previous analysis of 19 Echo-202 melanoma patients, the new positive data are likely to amp up expectations for the Echo-301 trial, a phase 3 test of the Keytruda-epacadostat pairing against placebo in several cancer types. That trial is using a 100 mg, twice-daily dose of the Incyte drug. So, Saturday’s announcement highlighted that the results from Echo-202 were “generally consistent across dosing schedules” for epacadostat. 

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In a note based on the abstract data, Leerink analyst Michael Schmidt posited that the new analysis will strengthen expectations for the combo treatment’s phase 3 success—and for its ability to stand out among other treatment options for advanced melanoma.

“Importantly, data continue to compare favorably not only to historic Keytruda or Opdivo monotherapy results, but also compared to the combination of Opdivo with Yervoy in treatment-naïve metastatic melanoma patients,” Schmidt said, “which we think bodes well for the probability-of-success of the ongoing Echo-301 phase 3 trial.”

Merck and Incyte were set to discuss the results late Saturday in Madrid.

The early signs for the partnership were strong enough to inspire Merck to expand the joint testing in April. Merck & Co. said it would take the lead on developing the combo in a range of disease types, with first-line trials in non-small cell lung cancer, bladder cancer, kidney cancer and head and neck cancer.

But Merck isn't the only company to pair up with Incyte. Bristol-Myers Squibb, for one, expanded its own Incyte partnership, also in April. In addition to moving the combination of Opdivo and epacadostat into two phase 3 trials in NSCLC, the partners will add new cohorts to an ongoing melanoma study.