- Incyte released updated data on Saturday showing slightly improved efficacy from its closely watched combination study pairing the IDO1 enzyme inhibitor and Merck & Co.'s Keytruda (pembrolizumab).
- In 40 patients with non-small cell lung cancer (NSCLC), the overall response rate for the combo remained 35% — the same as previously reported when the study abstract was published in mid-May. But two patients who previously experienced a partial response are now in complete response.
- Investors are watching epacadostat closely as a promising agent to combine with checkpoint inhibitors in hopes of boosting the response rates seen with immuno-oncology monotherapy. As a result, Incyte shares have risen steadily and the company now commands a lofty valuation of just under $27 billion.
To date, the only non-chemotherapy combination approved in immuno-oncology is Bristol-Myers Squibb's couplet of Opdivo (nivolumab) and the CTLA4 inhibitor Yervoy (ipilimumab).
Although adding Yervoy to Opdivo has had success in melanoma, the combination results in higher toxicities. Blocking the IDO pathway is though of as an alternative to CTLA4 inhibition, possibly with lower side effects.
Encouraging results from the epacadostat/Keytruda combo seen in the abstracts released ahead of ASCO had boosted Incyte and further drove up optimism in IDO. Beyond NSCLC, Incyte's epacadostat/Keytruda combo also showed efficacy in bladder cancer and squamous cell carcinoma of the head and neck.
Merck had expanded its collaboration with Incyte back in April to test the combo in five different tumor types across seven pivotal trials, signaling confidence in its potential.
But some have urged caution in anointing IDO the next step forward in immuno-oncology.
"As encouraging as the data is, however, it still needs to be put in the context of Incyte's $10 billion plus valuation for epacadostat," said Brad Loncar, CEO of Loncar Investments.
"And in that respect, it's way too preliminary because there are too few patients and the data is not randomized so we don't actually know to what degree the responses are due to epacadostat or the Keytruda."
Piper Jaffray analyst Joshua Schimmer, has also expressed skepticism over epacadostat's additive efficacy, saying in a May investor note that he didn't view Incyte's ballooning market value favorably.
One thing in the combo's favor, though — responses were seen in both high- and low-expressors of PD-L1, a marker which is correlated with response to the current wave of checkpoint inhibitors.
Updated results are scheduled to be presented tomorrow and Monday in other cancers, as well as from a separate early study testing epacaodstat with Opdivo.