ASH: Seattle Genetics CEO sees a big new Adcetris market, but one analyst has some doubts

ATLANTAWith full data out from a trial of Seattle Genetics’ Adcetris in advanced, first-line classical Hodgkin lymphoma, company officials are looking for a new FDA approval early next year. But at least one analyst is iffy about the treatment’s prospects.

Sunday at the American Society of Hematology (ASH) annual meeting, the biotech presented data showing that the benefit of a regimen containing Adcetris plus doxorubicin, vinblastine, and dacarbazine was “limited” in certain subgroups, as SunTrust’s Yatin Suneja put it in a note to clients.

Suneja's review suggested that the majority of the cocktail’s benefit, unveiled in June, occurred in Stage 4 patients, who, according to the analyst's estimates, represent only about 26% of the overall patient pool. In stage 3 patients, the Adcetris combo “showed minimal effect," he wrote.

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Seattle Genetics, for its part, is hoping for a broad label in advanced Hodgkin lymphoma, for which it nabbed a breakthrough designation in October.

“I believe that if FDA goes ahead and approves this with a label that says ‘advanced Hodgkin lymphoma,’ I think that that would be very good because it puts it in the doctors’ hands to decide on their patients,” company CEO Clay Siegall said in an interview. “I like to give the doctors a tool and let them do their job. They’re very educated and very experienced, and to me, that’s the right label,” he added.

If Suneja's analysis is any indication, doctors may have quite a bit to sort out. The Adcetris combo regimen also performed far better in patients younger than 60; in patients older than 60, it failed to show an efficacy benefit at all, Suneja noted. And it’s the above-60 crowd that’s typically hit hardest by severe toxicity from bleomycin, a drug in the standard-of-care regimen that Adcetris replaces in the newcomer combo.

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“The risk of higher infections, likely due to increased neutropenia” seen with the Adcetris cocktailcoupled with the lack of efficacy benefitsuggest that uptake for A+AVD in this older age group could be more limited than anticipated,” Suneja wrote.

All things considered, “we believe the A+AVD combo is likely to be limited to younger (age <60 years) patients and/or those with Stage IV disease, which is likely to further restrict the total addressable patient population and hence the market potential of Adcetris,” he said.

And while he still expects to see an FDA approval, “we believe the market potential for Adcetris in this indication might be <$500 million,” he added.

The way Siegall sees it, however, Adcetriswhich the company has forecasted will bring in $300 to $310 million in the U.S. and Canada this yearwill eventually become a billion-dollar drug in those territories alone. If the drug can win a front-line nod, it will be “the biggest market opportunity that we have yet looked at,” Siegall said.

In advance of that possibility, the company decided in recent months to up the size of its sales force by about 30%, and now, “we think with the U.S. and Canada, we have it covered well,” he said. And if the company’s commercial team can launch the potential new indication the way it’s launched previous ones, it’ll be in good shape, he figures.

“We have very high market penetration to the modest market opportunities we currently have,” he said, adding, “We feel very good about how we’ve launched and continue to sell and market Adcetris.”