Nektar Therapeutics (NKTR)

[jondoeuk]

ASCO-SITC Clinical Immuno-Oncology Symposium abstract

Background: NKTR-262 is a novel intratumoral prodrug designed to promote tumor antigen release, an immune stimulatory environment, and antigen presentation. NKTR-214 increases CD8+ T cells and NK cells in the tumor microenvironment. The combination of NKTR-262 with NKTR-214 accesses innate and adaptive immunity to provide an abscopal response and systemic tumor immunity. The Phase 1b/2 REVEAL trial is enrolling.

Methods: In a 3+3 Phase 1 design, pts who are relapsed/refractory to ≥1 CPI receive escalating doses of intratumoral (IT) NKTR-262 followed by combined q3w treatment of IT NKTR-262 and fixed-dose intravenous (IV) NKTR-214 (0.006 mg/kg). Phase 1 will evaluate PK, safety, efficacy, and determine recommended Phase 2 dose. Scans are conducted every 9 wks (± 1 wk). Peripheral blood (PB) and tumor tissue are collected to measure biomarkers of immune activation. In Phase 2 expansion, NKTR-262 + NKTR-214 ± IV nivolumab (360 mg) will be assessed in specific tumor cohorts of IO-naïve and experienced pts.

Results: As of 06 Nov 2018, 11 pts had received at least one cycle of NKTR-262 + NKTR-214 therapy. 7/11 pts were efficacy evaluable with at least one on-treatment scan (4 MEL, 2 SARC, 1 CRC). 2/4 R/R melanoma pts had uPRs with 100% (scan 2) and 40% (scan 1) reductions in target lesions per RECIST 1.1, respectively. Both patients remain on treatment. Two SARC pts had stable disease at scan 1. No pts experienced G3 or higher TRAEs or immune-related adverse events (AEs). Most common G1-2 AEs were transient flu-like symptoms. Gene expression analysis of tumor and PB show dose-dependent induction (4 to 16-fold) of TLR target genes. Consistent with the mechanism of action for NKTR-214, PB flow cytometry shows an average 13-fold increase from baseline in Ki67+ CD8+T cells in 6 pts.

Conclusions: NKTR-262 + NKTR-214 engage the immune activation cascade from local tumor antigen production to anti-tumor T cell response. Initial dose levels of NKTR-262 with fixed-dose NKTR-214 were well-tolerated with early evidence of clinical activity. These data support continued evaluation of the combination +/- nivolumab. Clinical trial information: NCT03435640

https://meetinglibrary.asco.org/record/170420/abstract