Preliminary data from QUILT 3.055: A phase 2 multi-cohort study of N803 (IL-15 superagonist) in combination with checkpoint inhibitors (CPI).
John Wrangle, Mark M. Awad, Firas Badin, Mark P. Rubinstein, Paul Bhar, Chad Garner, Sandeep K. Reddy, Patrick Soon‐Shiong
Abstract
2596 Background: There is currently a paucity of treatment options for checkpoint relapsed patients who have had an initial response but subsequently progress. N803, a novel IgG1 Fc-engineered IL-15-complexed protein may rescue checkpoint activity in a checkpoint independent manner via its selective enhancement of natural killer cell (NK) and CD8+ T cell number and function, without stimulation of T regs and MDSCs. Methods: QUILT 3.055, (NCT03228667) a phase 2b study of N803 plus investigator choice CPI in 11 tumor types: NSCLC, SCLC, Urothelial carcinoma, HNSCC, Merkel cell carcinoma, Melanoma (single PD-1/PD-L1 CPI or w/ ipilimumab), Renal cell carcinoma (RCC), Gastric cancer, Cervical cancer, Hepatocellular carcinoma, Microsatellite instability-high (MSI-H)/ mismatch repair deficient (dMMR) solid tumors, with a heterogeneous mix of prior therapies. We present interim data for 135 patients treated with CPI alone or in combination with chemotherapy as their most recent prior therapy. Trial inclusion required investigator assessed progression on last line of therapy, patients had either CR with relapse or partial response or stable disease for 6 months with progression as their most recent result of checkpoint therapy. Patients with hyperprogression or best initial response of progression were excluded. Subjects received N803 15mck/kg SC q 3 weeks in combination with the same checkpoint inhibitor on which they had their most recent progression. Results: Preliminary data from 135 patients (60% NSCLC) with treatment with checkpoint and N-803 following progression on the same checkpoint show CR 0%, PR 8%, Stable Disease 51%, Progression 29%, response unevaluable 12% to date. A PR or SD was seen in all subgroups. Median PFS 3.9 months (95% CI: 2.6,5.0). Median OS 13.8 months (95% CI: 11.8, 16.3) N-803 is well tolerated with grade 1-2 common N-803 treatment related adverse events (TRAE) were injection site reaction (68%), chills (32%) fatigue (26%), pyrexia (26%), flu-like illness (14%), nausea (12%) and no other individual AE > 10%. Grade 3 N-803 TRAE were 12% but no individual grade 3 AEs were greater than 5%. Conclusions: N803 demonstrates low toxicity in patients previously treated with CPI and promising efficacy of cessation of progression and induction of response and durable stable disease in patients who had previously progressed on a CPI containing regimen in multiple tumor types and different CPIs. Clinical trial information: NCT03228667.