Athenex discloses patient death, clinical hold on CAR-NKT trial as it seeks strategic alternatives

A neuroblastoma patient has died after receiving Athenex’s natural killer cell therapy, triggering a clinical hold, the company revealed.

Baylor College of Medicine, which is running the trial, has identified some of the conditions leading up to the patient’s death and is “devising a safety risk mitigation plan” to reopen the trial, according to Athenex. It did not return requests for comment on when the patient’s death occurred.

The biotech tucked the disclosure in its business update for the fourth quarter and full year of 2022, where it also said it will explore a “broader range of strategic alternatives.”

Athenex has spent much of its 20-year life working on a platform tech that it hoped could turn commonly used intravenous chemotherapies into pills, while also manufacturing active pharmaceutical ingredients and compounding drugs for clients. But in the wake of an FDA rejection, it retooled its whole strategy and downsized last year, selling off its manufacturing plants and pivoting to cell therapies after acquiring Kuur Therapeutics in a $70 million deal consisting primarily of equity in 2021.

The lead candidate, KUR-501, is made up of NKT cells engineered with a CAR targeting GD2 and designed to secrete IL-15 at the tumor site. At the time of the buyout, Athenex touted one complete response, one partial response and three patients with stable disease out of 10 neuroblastoma patients dosed in Phase I.

The trial was designed to enroll a total of 36 children and adolescents aged 1 to 21 with relapsed/refractory high-risk neuroblastoma.

Athenex noted the male patient who died was young and heavily pretreated. He was found to have human metapneumovirus infection, then Grade 1 cytokine release syndrome — a common side effect of CAR-T therapies — that was treated with immunosuppressants.

Johnson Lau

He later developed polyclonal hyperleukocytosis, where white blood cells grow out of control, which was complicated by what Athenex described as “multiorgan dysfunction without evidence of sepsis.” He died three weeks after receiving KUR-501, at the fifth dose level of 300 million cells/m2.

Athenex is hoping to restart the trial in mid-2023, given the FDA lifts the clinical hold. It’s expecting safety and preliminary efficacy data in the second half of the year. There are two other CAR-NKT programs from Kuur it’s pushing forward, one in Phase I and another with an IND planned for 2024.

CEO Johnson Lau said his focus for the year will be “improving our balance sheet as we continue to advance our promising clinical development programs.”

It remains to be seen how much longer the company can go. At the end of 2022, it had cash, cash equivalents and restricted cash balance of $35.6 million. In its update Monday, Athenex said it “is implementing cost savings programs and plans to monetize assets and raise capital in order to extend cash runway in 2023.”

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