- The Food and Drug Administration on Tuesday approved a combination of Seattle Genetics Inc.'s cancer drug Adcetris together with chemotherapy for frontline treatment of advanced Hodgkin lymphoma, marking the first new regimen OK'd in over 40 years for patients newly diagnosed with the blood cancer.
- In first-line Hodgkin lymphoma, patients commonly receive a cocktail of chemo drugs known by the acronym ABVD. A recent study by Seattle Genetics showed replacing bleomycin — the "B" in the standard regimen — with Adcetris significantly extended progression-free survival compared to ABVD.
- Expanding the addressable market for Adcetris is a crucial step for the Washington-based biotech, which relies on the drug for most of its revenues.
Approval of the Adcetris (brentuximab vedotin) combo came five weeks ahead of the FDA's scheduled decision date of May 1. SeaGen, however, has been preparing to market the drug more widely, recently adding 30 new sales representatives in the U.S. to support a broader label.
The company believes Adcetris can eventually become a blockbuster drug in the U.S., counting on new approvals to expand the number of patients it can reach. Adcetris sales in 2017 totaled just over $300 million for SeaGen, up 16% from the year prior.
Under a partnership with Takeda Pharmaceutical Co. Ltd., SeaGen markets Adectris in the U.S. and Canada while the Japanese drugmaker sells it in the rest of the world.
Over 8,200 people in the U.S. were diagnosed with Hodgkin lymphoma last year, according to estimates from the National Cancer Institute cited by the FDA in its statement on approval.
Many of those patients likely initially were treated with ABVD, a combination of the chemo drugs doxorubicin, bleomycin, vinblastine and dacarbazine. Bleomycin, however, is associated with erratic and at times fatal lung toxicity, driving interest in a replacement that could lower the regimen's overall safety risk.
In a study known as ECHELON-1, Adcetris paired with AVD reduced the risk of disease worsening, death or a non-complete response by 23% compared to ABVD. Importantly, fewer cases of lung toxicity were reported in the Adectris arm.
SeaGen says it has seen strong interest from physicians in the ECHELON-1 results and believes the Adcetris combo is better suited for use by community oncologists.
Still, adding Adcetris comes with its own risks. Patients who received the drug plus AVD experienced more frequent peripheral neuropathy and neutropenia — a safety risk the FDA hopes to mitigate by recommending prophylactic treatment with G-CSF, a growth factor that promotes the production of white blood cells.
Investors were also modestly disappointed Adcetris didn't drive higher efficacy in ECHELON-1. At the time of the interim analysis, results showed a trend in overall survival favoring the treatment arm but the data was not statistically significant.
Shares in Seattle Genetics fell by about 1.5% Wednesday morning, likely reflecting a reaction to the label granted by the FDA.
The company is looking forward to reporting results later this year from another Phase 3 study of Adcetris in peripheral T-cell lymphoma, which could represent another area of growth.