Dual-target CD70/CAIX CAR-NK Cells for Advanced Clear Cell Renal Cell Carcinoma

Overview

Phase 1/2 study evaluates the safety, feasibility, and preliminary antitumor activity of allogeneic dual-target CD70/CAIX CAR-NK cells after fludarabine/cyclophosphamide lymphodepletion in adults with advanced or metastatic clear cell RCC that has progressed after standard therapy. The study is designed to determine a recommended dose and schedule, characterize hepatobiliary safety, and explore whether CD70-high, CAIX-high, or dual-high tumors derive the greatest benefit. Biomarker-defined activity signals will be used to guide whether later development should prioritize CD70, CAIX/CA9, or continued dual-targeting.

Advanced clear cell RCC remains difficult to treat after immune checkpoint blockade and VEGF-pathway therapy. Both CD70 and CAIX are attractive RCC targets: CAIX is broadly expressed in clear cell RCC, while CD70 is frequently overexpressed and has already generated encouraging clinical cell-therapy signals in RCC \[3-11\]. The investigational product in this example is an allogeneic, cord blood-derived NK cell product engineered to express a dual CAR recognizing CD70 and CAIX/CA9, membrane-bound IL-15 to enhance persistence, and an inducible caspase-9 safety switch to improve controllability. The allogeneic CAR-NK strategy is intended to provide an off-the-shelf platform with lower theoretical risk of graft-versus-host disease than allogeneic T-cell products and with innate NK killing as a complementary antitumor mechanism \[1, 2, 11\]. The study uses a standard dose-escalation phase followed by a biomarker-guided expansion phase. All participants receive lymphodepletion with fludarabine and cyclophosphamide and then one infusion of dual-target CAR-NK cells on Day 0; an optional second infusion on Day 15 is allowed for participants without doselimiting toxicity, uncontrolled cytokine-mediated toxicity, or rapid progression. During expansion, participants remain in a single treatment arm but are prospectively analyzed in CD70-high, CAIX-high, and dual-high subgroups. Because earlier CAIX CAR-T studies in metastatic RCC reported on-target hepatobiliary toxicity related to low-level CAIX expression in biliary epithelium, this example protocol incorporates enhanced liver screening, exclusion of significant biliary disease, staggered first-patient dosing at each dose level, frequent liver function monitoring, and an explicit early stopping rule for recurrent protocoldefined hepatobiliary toxicity \[5, 6\]. The translational objective is not only to identify a recommended phase 2 dose but also to learn which antigen context appears most actionable in patients. If activity clusters in CD70-high tumors with cleaner safety, later development may pivot toward a CD70-led construct. If CAIX-high tumors uniquely benefit without meaningful hepatobiliary toxicity, CAIX/CA9 may remain central. If dual-high tumors clearly outperform single-high tumors without added risk, the dual-target program should continue.