#ESMO20: Seattle Genetics eyes 4th approval with new data in a crowded field
Does Seattle Genetics have another approval on its hands?
The last 12 months, not so great for the world, has been great for Seattle Genetics. The company landed two separate FDA approvals, signed a $4.5 billion deal with Merck and watched antibody-drug conjugates — the technology they spent years developing to broad industry skepticism — emerge suddenly as one of the most popular approaches in oncology. And on Monday at ESMO, the company and their partners at Genmab unveiled the data behind the ADC it hopes will provide its next major FDA approval.
In a pivotal Phase II study of their experimental drug tisotumab vedotin, 101 patients with recurrent or metastatic cervical cancer had an objective response rate of 24%, with that response lasting a median of 8.3 months. It was a single-arm trial, but Seattle Genetics compared the results to data suggesting existing therapies “typically” have a response rate of less than 15% and patients survive for 6 to 9.4 months.
By contrast, median survival in the study was 12.1 months, with 79% of patients alive after 6. The overall survival numbers were reported in the initial readout in June.
“It’s a very good step and another option for patients in a disease with a grim prognosis,” CEO Clay Siegall told Endpoints News.
The full data also showed eye issues as one of the most likely side effects. That’s particularly noteworthy after the FDA raised serious concerns about the ocular issues posed by a GlaxoSmithKline ADC, but Siegall said the issues were unrelated and that the adverse events should be preventable with the right measures such as eye drops.
“That has a completely different type of drug attached to it,” Siegall said, attributing GSK’s problem to solubility issues.
The best option for cervical cancer is Merck’s HPV vaccine, which prevents the disease at a high rate, but not everyone gets the vaccine and treatment choices for those diagnosed are highly limited. After the topline results came out, Cowen analysts noted that Keytruda had won approval on an objective response rate of just 14.3%. “And that is only in the setting where they have high PD-1,” Siegall noted.
Seattle Genetics, though, aren’t alone in the race for new cervical cancer therapies. Most notably, Iovance saw a 44% response rate in cervical cancer from the cell therapy data they unveiled a little over a year ago at ASCO 2019.
That’s undoubtedly better, but analysts have generally seen a future for both therapies. Any improvement over the Keytruda data will likely find open doors at the FDA and Baird’s Madhu Kumar has argued that both could eventually be used to treat patients, with doctors giving chemo, cell therapy and then Seattle Genetics’ antibody-drug conjugate.
For now, Seattle Genetics is overseeing the next wave of trials while prepping a BLA submission. In a much-watched study, they will combine Keytruda with the ADC, and they will also enroll a randomized control trial, where the ADC goes up against doctor’s choice.
They also plan to push ADC into other tumor types that also express tissue factor. The goal, he said, is to position ADCs further as part of a broad suite of technologies now being leveraged to curb cancer.
“While ADCs are not by themself are not going to be the only thing needed to treat cancer – you’ll need other types of therapies that treat the outside of the cell, the inside of the cell and the cells around the tumor,” he said. “But it does show you the need for ADCs to be a bigger part of that, and it’s only getting larger.”