Nektar's NKTR-255 After CD19 CAR-T Therapy Enhances Complete Response In R/R Large B-Cell Lymphoma

(RTTNews) - Nektar Therapeutics (NKTR) announced results of its Phase 2 proof-of-concept study, which evaluated NKTR-255 as an adjuvant treatment to enhance complete response rate (CRR) and durability following CD19-directed CAR-T therapy in patients with relapsed/refractory (R/R) Large B-cell Lymphoma (LBCL). 73% of the NKTR-255 treatment group compared to 50% of the placebo group achieved a complete response at 6 months. NKTR-255 enhanced CAR T-cell kinetics with improved CD8+ CAR-T area under the curve (AUC) 0-15 days post-administration being 5.8-fold greater than placebo-controls, as per the trail results.

NKTR-255 is an investigational polymer-conjugated IL-15 agonist, that activates, proliferates and expands natural killer (NK) and CD8+ T-cells in vivo, as well as promotes the survival and expansion of memory CD8+ T cells intended to increase duration and level of response for CAR-T and cellular therapies.

In this multicenter, double-blind Phase 2 study, patients were randomized to receive one of three dose regimens of NKTR-255 or placebo intravenously starting 14 days after CAR-T infusion. In the fifteen-person clinical trial, the NKTR-255 combined treatment group demonstrated an improved CRR at six months, achieving 73% compared to 50% for the placebo, as assessed by a blinded independent central radiology review.

Additionally, two patients treated with NKTR-255 converted from stable disease or partial response to complete responses at six months. No conversions from stable disease or partial response to complete response were observed in the placebo arm of the trial.

The company noted that the reported clinical benefit surpasses the published historical benchmark data from multiple pivotal trials and real-world meta-analyses of currently available commercial CD19 CAR-T cell therapies, which demonstrate 6-month complete response rates of 41% to 44%.

NKTR-255 was safe and well-tolerated in patients with relapsed/refractory LBCL in combination with FDA-approved CD19 CAR T-cell products.

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