- A bet by biotech Epizyme on the potential of a targeted cancer drug paid off on Thursday with a Food and Drug Administration approval for Tazverik, nearly five years after the Cambridge, Massachusetts-based company bought back rights to the therapy from Japan's Eisai.
- Tazverik, Epizyme's first drug, is conditionally cleared for people with a rare type of soft tissue sarcoma that's spread and can't be treated with surgery. The FDA made its decision based on Phase 2 trial results that showed Tazverik shrank tumors in a minority of treated patients with epithelioid sarcoma.
- While the response rate to Tazverik was modest, metastatic epithelioid sarcoma is aggressive and median overall survival is less than one year, according to Epizyme. Patients who did benefit from treatment experienced responses that lasted a median of 16 months, study data showed.
Only a few hundred people are diagnosed with epithelioid sarcoma each year in the U.S. Often misdiagnosed, the cancer type is usually treated with drugs broadly approved for soft tissue sarcomas, a group of which epithelioid sarcoma is a part.
Approval of Tazverik gives doctors the first treatment option specifically approved for the disease, a factor which likely played a role in the FDA's review of the drug.
Only 15% of the 62 patients enrolled in the epithelioid sarcoma portion of Epizyme's Phase 2 study experienced tumor responses deep enough to qualify by standard metrics for evaluating drug activity. The cancers of 30 patients, meanwhile, were judged to be stable following treatment.
Median overall survival stretched out to 19 months, helped by the comparatively durable responses experienced by the minority of responding patients. As the study did not compare Tazverik to a control treatment, how that compares to existing therapies is unclear.
"All tumors aren't created equal and epithelioid sarcoma is one of these tumor types that is notoriously resistant to treatment," said company CEO Robert Bazemore in an interview.
"The response rate that we're seeing, although it seems modest, would compare favorably to the other drugs and regimens that are used to treat these patients."
A panel of independent experts convened by the FDA in December recommended by an 11-0 vote that Tazverik's benefit outweighs the drug's risk.
Documents prepared by FDA staff for that meeting, however, raised questions about the response rate observed in Epizyme's study, noting the agency was "concerned" the data did not provide sufficient evidence of benefit.
Just over a third of epithelioid sarcoma patients taking Tazverik experienced serious adverse reactions like hemorrhage or skin infections, and a similar proportion had to pause taking the drug due to side effects. The label approved by the FDA also warns of the risk of secondary cancers, such as lymphoma and leukemia.
While Tazverik's approval was based on efficacy data from only 62 patients, Epizyme has safety data from more than 600 people who received the approved dose of the drug across other study cohorts and cancer types.
Approval also marks Epizyme's transition to becoming a commercial biotech. The company priced Tazverik at $15,500 for one-month's supply, a hefty price tag similar to the cost of other recently introduced cancer drugs.
List prices of select cancer drugs approved in 2019 and 2020
|Drug||Cancer type treated||List price per month|
|Ayvakit||Gastrointestinal stromal tumor||$32,000|
|Balversa||Bladder cancer||Between $10,080 and $22,680*|
|Brukinsa||Mantle cell lymphoma||$12,935|
*Per 28-day supply **Based on patient weight of 72 kg ***Priced at $90,000 for four-month regimen
The FDA's decision is conditional on Epizyme completing a larger confirmatory study that is just getting underway. A safety run-in portion of the trial is expected to finish this year, with the Phase 3 stage to follow.
Epizyme also agreed to expand enrollment in another cohort of its Phase 2 test and will conduct several post-marketing evaluations as well.
The company hopes to soon win a second OK for Tazverik in follicular lymphoma, a more prevalent cancer for which Epizyme submitted an approval application to the FDA in December.
"As we're launching in epithelioid sarcoma, we'll already begin making the transition to be ready to launch in follicular lymphoma," said Bazemore, indicating that together the two indications represent a $1 billion-plus market opportunity.
The FDA still has to accept Epizyme's lymphoma application, but, should it grant Priority Review, a decision could come as soon as this summer.