Separating hope from hype in the latest cancer treatment ‘revolution’

Print 28 September 2016
Damian Garde / STAT

There’s new hope that a much-hyped class of immunotherapies could revolutionize cancer treatment: Data released this week from an early test on patients stirred hope that the first such therapy could hit the market soon.

But experts remain cautious about safety and efficacy — and warn that big questions remain.

Kite Pharma, a California drug developer, is touting positive early results with a treatment for a severe form of lymphoma that doesn’t respond to available drugs. The therapy, called a CAR-T, is made by extracting a patient’s own immune cells and re-engineering them to target cancerous growths, turning the body’s own defenses on tumors.

Kite’s treatment is leading a group of similar therapies, all of which have shown promise in early studies on forms of cancer with dismal survival rates.

But Kite’s data remains incomplete. Among the unanswered questions:

Does it work?

It seems to. But for how long remains an outstanding question. In Kite’s clinical trial, the therapy sent about one-third of patients into complete remission. Historically, only 8 percent of patients with such severe lymphoma achieve remission on standard therapy, the company said, meaning Kite’s therapy could be a significant advance.

But those results are based on just three months of measurements from 51 patients. In that time frame, seven patients who initially went into remission suffered relapses.

That’s a “meh” result, tweeted Sally Church, an oncology expert and former Novartis employee. It’s not the number of remissions that counts; it’s their durability, she said.

A few Wall Street analysts sounded a similar note of caution, warning that until data from six and nine months are available, it will be hard to draw broad conclusions about Kite’s therapy.

Will the FDA approve it?

The consensus would seem to be yes — eventually.

Under the leadership of Dr. Richard Pazdur, the oncology division of the Food and Drug Administration has been enthusiastic about granting early approvals to novel treatments that could help particularly desperate patients. Kite’s therapy would seem to fit that bill, according to analysts from Cowen and RBC, who predicted the company could win approval based on the three months of results disclosed Monday.

But the FDA might balk at signing off on a first-in-class treatment with so little supporting data.

Kite is optimistic that its three-month remission rate will endure, pointing to an earlier trial in which patients stabilized after six and nine months. But that study involved just seven people, and regulators might want to hold off until there’s a fuller picture of the therapy’s effect. Last week, an FDA medical officer told analysts at Jefferies that she’d like to see at least six months of data, noting that she was speaking for herself and not on behalf of the agency.

If the FDA buys Kite’s pitch, the treatment could be available to patients next year. If it elects to wait, the process could drag into 2018.

Is it safe?

Safety is always relative in the world of oncology drugs.

In Kite’s trial, two patients died of issues related to cytokine release syndrome, a severe and often deadly immune system reaction to a foreign body. It’s a common side effect of CAR-T therapy, observed in numerous trials across the field.

On the other hand, “these are truly sick patients with heavily pretreated” cancer, Kite Chief Medical Officer Dr. David Chang said on a conference call Monday. Without CAR-T therapy, their median survival is just six months. The risks, Chang argued, are worth it.

For its part, the FDA has seemed to agree. Juno Therapeutics, one of Kite’s CAR-T rivals, had to pause a key study after a string of patient deaths. The FDA, not generally known for its speed in decision making, allowed the company to get back to work after less than a week. To outsiders, that signaled the agency’s belief that CAR-T’s benefits likely outweigh its risks.

But safety concerns “could negatively impact the uptake even if they get regulatory approval,” said Dana Gheorghe, a senior analyst at biopharma consultancy Decision Resources Group.

Many analysts have penciled Kite’s product in for sales of more than $1 billion a year, but the company may have a hard time reaching that milestone if physicians are wary of the treatment’s side effects and unsure of its longevity.

What’s next?

Novartis is pressing forward with a CAR-T therapy for children who have a severe type of leukemia; it’s planning to file for approval next year. And Juno is just behind with a similar treatment for adults with the same disease. The outcome of Kite’s FDA submission will likely affect their future regulatory plans.

“Any time there’s a company that has an innovative product that FDA has never seen before, having one company go through that process helps the agency and industry figure out what the issues are and what the regulations are going to look like,” said Patricia Zettler, a professor at the Georgia State University College of Law who specializes in FDA policy.

The CAR-T field is young, but it’s already been through the biotech hype cycle. A year ago, oncologists were beamingly optimistic about its promise, and Juno and Kite saw their shares hit an all-time high.

But it has since become clear that CAR-T is no panacea for cancer. The field’s first projects have found success targeting CD19, a protein expressed by certain cancer cells, but have had mixed results against other targets. And none of the contenders has managed to demonstrate that CAR-T might have a future in solid tumors, which are much more common than blood cancers.

At an immunotherapy-focused meeting in New York this week, leaders in oncology cautioned against exuberance. Treatments like CAR-T present tremendous potential, they said, but there’s a long road ahead.

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