The latest immuno-oncology market-share numbers are out, and they show that Merck & Co.’s Keytruda is not only gaining on Bristol-Myers Squibb archrival Opdivo, but it’s picked up the pace, too.

Over the course of June, Keytruda’s share increased by four percentage points to 32% "at the expense of" Opdivo, Leerink Partners analyst Seamus Fernandez wrote in a Wednesday note to clients, citing sales data from Symphony Health.

That data suggests "a greater month-over-month improvement for Keytruda than in months past," he added. Bristol-Myers' overall I-O share, which includes Yervoy’s piece of the pie, dropped to 61% from 64%.

Now approved for a half-dozen cancer types, Opdivo jumped to an early I-O lead after leapfrogging first-to-market Keytruda with its quick lung cancer approval, and it still leads with 46% of the market. But Keytruda has blown past it in the all-important lung cancer space. Merck’s contender has racked up both monotherapy and combo frontline approvals, while Bristol-Myers'—which has already flopped as a monotherapy in previously untreated patients—likely won’t even have its combo data until early next year.

Keytruda has gone on a recent approval spree, too, adding a nod in microsatellite instability-high cancer and bagging a priority review in stomach

That’s not to say Opdivo hasn’t chalked up regulatory wins of its own. For one, the med snagged a priority review in liver cancer in May. But lately, new Keytruda data has prompted industry watchers to ask whether Bristol is "falling behind"; in a post-ASCO article, Barron’s wrote that "in the near-term the fight is uphill" for the New Jersey drugmaker.

Meanwhile, the two are hardly alone on the immuno-oncology front. Bristol-Myers' Yervoy, the first-ever approved immunotherapy, still holds a 15% piece of the pie, Fernandez said, good for the No. 3 spot. Roche’s Tecentriq, first approved last May in bladder cancer, "has remained steady at 7% market share since the beginning of 2017," he wrote, while Bavencio and Imfinzi—brand-new meds from the Pfizer-Merck KGaA team and AstraZeneca, respectively—have so far "achieved only a nominal share."