- Fate Therapeutics reported new results for two early-stage studies testing two different types of experimental lymphoma treatments that utilize natural killer cells, a fast-emerging form of cancer immunotherapy.
- Eight of 11 lymphoma patients who received one Fate NK cell therapy, FT516, have shown evidence of a response, as have 10 of 14 given another known as FT596. No serious neurological side effects were reported, and only two Grade 1 or Grade 2 cases of the immune-related adverse events typically associated with other forms of engineered cell therapy were observed.
- Still, it's unclear how well Fate's NK cell treatments stack up to more proven T cell-based therapies. Five of the eight responses to FT516 held up after a median of close to six months, for instance. And only one of those patients' cancers has been in remission for that long, a key potency measure for cell therapies. Fate shares were down about 11% in pre-market trading Friday morning.
Immunotherapies harnessing natural killer or "NK" cells, the body’s front-line defenders against foreign invaders, have drawn considerable interest from drugmakers of late, as they represent a potentially safer and more convenient alternative to the powerful, but logistically complex T cell-based treatments available for a handful of blood cancers.
Fate and others have shown these treatments have promise treating acute myeloid leukemia, for which there is a history of non-engineered donor NK cells being used to successfully treat the disease. What’s more, treatment has, so far, had a cleaner safety profile than so-called CAR-T therapies, enabling patients to be potentially dosed more than once. That potential has spurred a recent spate of investments in, and deals with, NK cell therapy developers.
But it’s unclear, as of yet, what role NK cell treatments will play in cancer care. Clinical tests are early and have yet to prove how potent or long-lasting the effects of NK cell therapies are compared to their T cell counterparts. The results Fate disclosed Thursday do little to answer those questions.
Fate reported results from two treatments, both of which are NK cells engineered to have certain characteristics to boost their effects. On the positive side, overall response rates appeared in the range of what’s been observed with CAR-T, and Fate has yet to observe any side effects that would prevent testing of higher doses.
Stifel analyst Benjamin Burnett, for instance, noted that four of seven (57%) patients who had diffuse large b-cell lymphoma-like cancers responded to FT596 and three of them (43%) showed evidence of remission. Those figures are "close, though still a bit below" the roughly 70% response rate and 50% remission rate established by CAR-T therapies, Burnett wrote.
But the rate of remissions, or "complete" responses, six months after treatment with FT516 — a key hurdle for cell therapies to meet — hasn’t yet matched the 30% to 35% rate T cell therapies have shown. Cancers progressed for two patients with complete responses after four and five months, respectively. A third with a partial response was given a different cancer drug after four months.
The results sent shares of Fate — which is currently worth more than $8 billion, far more than peers like Nkarta — down 11%. Analysts were mixed on the findings, however. Burnett, for instance, noted that responses could "deepen" with time or improve with higher doses, and that some patients who hadn’t responded to CAR-T did to NK cell treatment.
"The data set is too immature to conclude anything about durability," he wrote.
But the results, especially in aggressive B-cell lymphoma patients, are nonetheless "at the low-end" of rival CAR-T and NK cell therapy programs, wrote SVB Leerink analyst Daina Graybosch. The data are also difficult to interpret because Fate enrolled a diverse mix of patients. "We would not be surprised with some stock sell-off today," she wrote.
Fate’s next update, which will include results from higher doses of FT596 and a longer look at the durability of FT516, will come at the American Society of Hematology meeting in December.