- Seattle Genetics is known best for Adcetris, a cancer drug and its only approved product. Results from two studies presented over the weekend suggest the Bothell, Washington-based biotech's future could be more diversified.
- In one, a Phase 1 trial combining Seattle Genetics and partner Astellas' enfortumab vedotin with Merck & Co.'s Keytruda, data showed the drug pairing shrank tumors in 32 out of 45 previously untreated patients with metastatic bladder cancer — a response rate markedly higher than what Keytruda's shown alone.
- Results from the other, a single-arm Phase 2 study of Seattle Genetics' tucatinib, also impressed, raising confidence among Wall Street analysts the drug can hit its mark in a large study due to read out later this year.
Seattle Genetics appeared the winner of a weekend of cancer drug updates at the European Society of Medical Oncology's annual meeting, held in Barcelona, Spain.
Shares in the biotech rose by more than 10% Monday morning, second only to Dova Pharmaceuticals among companies listed on the iShares Nasdaq Biotechnology Index. (Dova was acquired Monday by Swedish drugmaker Sobi at a 59% premium to the average price of its shares over the past month.)
Seattle Genetics has largely been a one-drug story since 2011, when its antibody-drug conjugate Adcetris (bretuximab vedotin) first secured approval in the U.S.
Sales have steadily grown, but investors are eager to see what the company's next act will be. An answer could come as soon as next March, a date set by the Food and Drug Administration for deciding whether to approve enfortumab vedotin for previously treated metastatic bladder cancer.
Data supporting that application were unveiled in June and, now, the study results from ESMO hint at the drug's potential as a partner therapy in the first-line setting.
Six of the 45 patients treated with enfortumab vedotin and Keytruda (pembrolizumab) experienced a complete response, while another 26 had their tumors partially shrink following treatment — making for a 71% response rate.
Keytruda's already approved on its own for bladder cancer, supported by data showing the drug yielded a 29% response rate in a similar patient population as studied in Seattle Genetics' trial. Adding enfortumab vedotin, then, appears to significantly improve the share of patients who respond to treatment.
"Notably, preliminary analysis showed consistent response regardless of PD-L1 expression status, an Achilles heel for PD-1 agents in this setting," wrote SVB Leerink analyst Andrew Berens, referring to a biomarker used to select patients for immunotherapy, in a Sept. 29 note to clients.
Half of patients had a side effect rated higher than or equal to Grade 3, although only four discontinued treatment due to drug-related adverse events. One patient died from multiple organ dysfunction syndrome that was judged to be linked to treatment by an investigator.
As with all combinations, safety will be a key question for how much potential pairing enfortumab vedotin with Keytruda could have.
Seattle Genetics leadership is already thinking ahead to a Phase 3 study, several analysts noted, and is considering which anti-PD-1 or anti-PD-L1 inhibitor would be the best partner therapy.
Stifel analyst Stephen Wiley said the results put Seattle Genetics "in an enviable strategic position" that could spur strategic collaborations talks with the five drugmakers currently marketing anti-PD-1 or anti-PD-L1 therapies for bladder cancer.
Data from the Phase 2 study of tucatinib, meanwhile, showed the drug combined with Roche's Herceptin (trastuzumab) led to responses in 52% of patients with colorectal cancer.
A bigger test, however, will be the Phase 2 HER2CLIMB study in breast cancer, which is expected to read out results before the end of the year.
Correction: A previous version of this article incorrectly identified tucatinib as part of the collaboration between Seattle Genetics and Astellas.