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promising new approach to cancer is moving closer to reaching patients, as the biotech company Kite Pharma prepares to make its case for Food and Drug Administration approval.

Kite announced Monday that its novel immunotherapy led to complete remissions for about one-third of patients with a severe form of blood cancer in a small clinical trial. The company believes those results will be enough to convince the FDA to let it on the market.

But there are caveats: The therapy has only been tested in a few dozen patients, the trial did not have a placebo arm, and the treatment can cause severe side effects, including abnormally low white blood cell counts, anemia, and neurological toxicities. Two patients died of treatment-related side effects during the trial, the company said.

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Another major question: How long the treatment will keep cancer at bay. Seven of the patients who first showed a strong response, with their cancer going into remission,  relapsed within three months.

If approved, Kite’s therapy would be the first so-called CAR-T treatment to reach the market, leading a heavily hyped class of cancer drugs that could bring in billions in revenue for their inventors.

Kite’s therapy, KTE-C19, is made by taking a patient’s own immune cells and rewiring them to home in on the tell-tale signs of cancer. Such treatments have shown early promise for some particularly deadly forms of cancer, but serious side effects and technological hurdles could cloud their future.

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KTE-C19 targets the most common form of non-Hodgkin lymphoma, a particularly aggressive cancer called diffuse large B cell lymphoma, or DLBCL. Most DLBCL patients go into remission after treatment with the cancer drug Rituxan and a battery of chemotherapy, but about one-third don’t respond to that regimen. It is these patients, who only survive for about six months on average, that Kite’s treatment aims to help.

Over three months, Kite’s therapy shrunk tumors for 39 percent of the 51 patients in the trial — and sent 33 percent into complete remission. Kite’s trial has no placebo arm, but for comparison purposes, the company points to historic data from 635 DLBCL patients treated with the standard of care. About 26 percent of them saw their cancer shrink, and just 8 percent had it disappear completely.

“These are remarkable responses for a patient population that has historically had a very poor outcomes,” Kite CEO Arie Belldegrun said on a conference call, “which is why we must never forget that for patients with non-Hodgkin lymphoma, every day matters.”

The question now is whether Kite’s results are good enough to merit FDA approval.

Wall Street analysts are all over the map in trying to predict what regulators might want to see from Kite. Some said the company would need a complete remission rate of around 50 percent, while others say it could win approval with half that.

And it remains possible that the FDA will decide to wait until Kite has six months or even a year of data from its trial. In the results Kite presented Monday, seven patients who first achieved complete remission suffered relapses after three months. Federal regulators might take a wait-and-see approach before giving Kite the green light, holding off on approval until they have a better idea of KTE-C19’s durability.

Kite’s latest results are preliminary and have not been peer-reviewed. The company plans to present full data at a scientific meeting this year, and management promised to disclose six-month results from the trial in the first quarter of 2017.

Kite is in the lead among companies racing to commercialize CAR-T therapies. If the FDA accepts its application, Kite could win approval next year. Behind it are Novartis, which expects to submit its CAR-T treatment in 2017, and Juno Therapeutics, which had to push back its commercial plans after the deaths of three patients delayed a key clinical trial.

This story has been updated with more information about Kite’s trial results.

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