BeiGene's Brukinsa misses in Imbruvica head-to-head, but analysts still chalk up a win

Investors have been keenly watching BeiGene’s blood cancer drug Brukinsa for clues to how much market share it can snatch from Johnson & Johnson and AbbVie’s Imbruvica. But Monday, Brukinsa came up short in a head-to-head trial against its blockbuster competition.

In the phase 3 study, BeiGene’s newcomer failed to significantly outdo Imbruvica at provoking complete responses—erasing signs of disease activity completely—or so-called “very good” partial responses in patients with Waldenstrom macroglobulinemia.

RELATED: BeiGene nabs landmark FDA nod for Brukinsa, kicking off challenge against blockbuster Imbruvica

While the Waldenstrom population is a relatively small one, industry watchers were using the trial to benchmark Brukinsa’s prospects against Imbruvica in other cancers—namely, chronic lymphocytic leukemia (CLL), where analysts are already forecasting a showdown in previously untreated patients.

The thing is, while Brukinsa might have missed the mark, the trial results still reflect well for the BeiGene med, SVB Leerink analyst Andrew Berens wrote in a Monday note to clients. “We believe this was largely an issue of statistical powering and outperformance for the Imbruvica arm,” he wrote.

BeiGene powered the trial to demonstrate that Brukinsa could double Imbruvica’s rate of complete or very good partial responses, Berens noted. And while it may have come up short of that goal, it still outdid the BTK class leader numerically, hitting that mark in 28.9% of relapsed or refractory patients versus Imbruvica’s 19.8%. It also led in the overall study population—which included patients new to treatment—with a rate of 28.4% versus Imbruvica’s 19.2%.

The BeiGene drug’s abilities to stave off disease progression and extend lives “were directionally consistent with the numerically higher VGPR rates,” he added, trending “in favor of Brukinsa.”

Brukinsa also came out ahead in the safety and tolerability department, where the company has looked to establish an edge for itself.

“Importantly, the Brukinsa safety/tolerability profile appears differentiated vs. Imbruvica, with less patients discontinuing treatment due to adverse events (AE), less fatal AEs, notably less atrial fibrillation (2% vs. 15%), less bleeding, and less diarrhea,” Berens wrote, adding that "the BGNE story has evolved to a much broader story, less dependent on superior efficacy outcome vs. Imbruvica in this trial."

RELATED: ASH: BeiGene, eyeing Imbruvica's CLL share, touts more early Brukinsa data

The results come close on the heels of phase 1/2 data from the closely watched CLL arena, presented at the American Society of Hematology annual meeting, that showed Brukinsa could produce a response in 95.9% of patients. That study also yielded a low discontinuation rate, BeiGene chief adviser Eric Hedrick—who previously worked at Imbruvica developer Pharmacyclics, now part of AbbVie—pointed out.

Imbruvica has “become difficult for many people to tolerate … beyond two years or so,” he said, adding that “those are toxicities we didn’t necessarily anticipate when we developed the drug.”

For now, though, Brukinsa bears just one approval, a nod in mantle cell lymphoma that it nabbed last month. Berens’ team predicts Brukinsa can generate 2021 sales of $220 million, with that figure leaping to $2.2 billion by 2025.