Nkarta underscores safety of CAR-NK, boasts early responses
The first generation of personalized CAR-T therapies made big waves in the treatment of lymphoma for their stunning efficacy. Nkarta is hoping its off-the-shelf natural killer cell approach will stand out on safety — while keeping some of those impressive numbers on responses.
In a new update from its Phase I dose escalation study, the South San Francisco-based biotech reported that seven out of 10 patients treated with the highest doses of its NK cell therapy, NKX019, achieved a complete response, translating to a complete response rate of 70%.
“The emerging safety profile of NKX019 is potentially game-changing,” said CEO Paul Hastings on an investor call.
NKX019 hits the same target as Yescarta and Kymriah, the first approved CAR-Ts. But there are some key differences: It consists of NK cells that are allogeneic, meaning doctors don’t need to go through the long process of harvesting cells from patients themselves and engineering them. And while most CAR-Ts are only infused once, some patients in the Nkarta trial were given multiple cycles of NKX019.
The new data build on an initial readout in April, when the company reported early responses. This time around, they have six more patients in the pool and a longer follow-up.
Specifically, Nkarta singled out the absence of cytokine release syndrome or neurotoxicities, which have been the hallmark of early CAR-T drugs.
“While occasional transit and manageable infusion-related reactions were observed and some were even labeled as CRS by our investigators, the early onset and prompt resolution of symptoms, sometimes without any intervention at all, is clearly not the classic CRS that is seen with CAR-T cell therapies,” Hastings added.
Having enrolled and dosed 19 patients in the trial so far, investigators observed five complete responses across all dose levels after just a single cycle — with additional cycles, three partial responses deepened to complete responses.
Ten of the patients were in the highest dose cohorts, getting either three weekly doses of a billion cells or three weekly doses of 1.5 billion cells per cycle. Either of those achieved an objective response, including seven complete responses.
Execs alluded to durability by noting in the call that five patients had complete responses that exceeded six months, including one patient with LBCL who has maintained CR for over nine months.
Nkarta added that it’s administering what it calls consolidation dosing to seven patients with CRs, with the goal of eradicating residual tumor cells and prolonging response.
“Having the ability to administer multiple treatment cycles gives us the opportunity to deepen responses in those patients who are showing a clinical benefit and to consolidate complete remissions with an additional cycle for those patients that achieve a CR,” said David Shook, vice president of clinical development.
If the responses hold up, Nkarta sees a wide range of potential ways for the drug to be deployed: as an option for patients who don’t have access or can’t tolerate CAR-T; as a next-line treatment for those who have relapsed after CAR-T; and in combination with other drugs, such as Roche’s Rituxan.
Editor’s note: A previous version of this story incorrectly stated that Nkarta did not offer numbers on durability. It’s been updated to include details provided in a presentation.
