Timing may not be everything. While Merck’s Keytruda was the first PD-1 inhibitor to debut in the US, one analyst says that Bristol-Myers Squibb could wind up the long-term winner in this category.

The FDA approved Keytruda (pembrolizumab) on September 4 for second-line use in patients with unresectable or metastatic melanoma, but before Keytruda could land on US shores a week later, BMS and its partner company Ono Pharmaceuticals had already begun launching Opdivo in Japan, making it the first of the new—and highly touted—class of cancer drugs to be made available.

BMS has said it plans to file Opdivo with the FDA for US marketing approval in the melanoma setting by September 30. If it gets approved here, the drug would be late to the party in the world’s biggest pharmaceutical market. Yet BMS and Ono could still win the day, says GlobalData analyst Fenix Leung, with Opdivo (nivolumab) positioned well for success in Europe and with an attractive combination therapy waiting in the wings. (BMS has already been selling a different immunotherapy, Yervoy, for melanoma since 2011, and has been testing it for use together with Opdivo.)

“BMS stopped the CheckMate-066 trial [of monotherapy Opdivo vs. dacarbazine in subjects with advanced melanoma] early due to favorable results, and the Committee for Medicinal Products for Human Use granted accelerated assessment for Opdivo at the end of July. It is clear that BMS is working on a tight deadline to push Opdivo ahead of Keytruda in the EU,” he wrote.

In addition to gaining that accelerated assessment overseas, BMS doesn’t appear to be resting on its laurels in the US, either. The drugmaker levied a lawsuit against Merck last week over patent infringement. The suit alleges that Merck violated a patent belonging to Ono and that Merck knew Opdivo was already in development when it began work on its own PD-1.

Keytruda is currently approved for a second-line indication in advanced melanoma (i.e. for patients who have already used Yervoy). Leung stated, however, that Keytruda’s likelihood of receiving a first- line indication may spur BMS/Ono to more aggressively pursue its Opdivo (nivolumab)/Yervoy (ipilimumab) combo therapy. “Keytruda is also likely to gain Food and Drug Administration approval as a first-line melanoma treatment in the US earlier than Opdivo. Since the latter is expected to reach the market a year after Keytruda, BMS may instead put forward a combination of Opdivo with Yervoy.”

“Combination strategies are essential in the race to capture a large share of one of the most promising markets in cancer immunotherapy,” he added.

BMS/Ono are currently investigating the combo in a head to head Phase-III trial against Yervoy alone—dubbed CheckMate-067. CheckMate-067 showed a median overall survival of 40 months in patients—more than double what either drug showed on its own. The trial is expected to read out in Fall 2016.