Circulating kidney injury molecule-1 (KIM-1) biomarker analysis in IMmotion010: A randomized phase 3 study of adjuvant (adj) atezolizumab (atezo) vs placebo (pbo) in patients (pts) with renal cell carcinoma (RCC) at increased risk of recurrence after resection.

4506 Background: In IMmotion010, adj atezo did not prolong investigator-assessed disease-free survival (DFS; primary endpoint) vs pbo after resection in pts with RCC (HR: 0.93, 95% CI: 0.75, 1.15; P=0.50; Pal Lancet 2023). This exploratory analysis of circulating protein biomarkers was performed to identify high-risk pts with minimal residual disease (MRD) who may show differential benefit from treatment (tx) with atezo. Methods: Pts with RCC with clear-cell or sarcomatoid component and increased recurrence risk post nephrectomy were randomized 1:1 to atezo 1200 mg or pbo IV q3w for 16 cycles or 1 year. A retrospective proteomics analysis was done with an affinity-based proximity extension assay (PEA) panel of ≈3000 analytes to identify circulating proteins with differential abundance patterns in matched serum samples (baseline vs at recurrence). A high sensitivity electrochemiluminescence (ECL) assay was then used to evaluate levels of KIM-1, a membrane glycoprotein overexpressed in clear-cell and papillary RCC, in all available baseline and post-tx serum samples. Outcomes in pts with KIM-1 high (≥86 pg/mL) vs low status at baseline were analyzed. Results: In pts with matched PEA samples (n=73), circulating KIM-1 was identified as the most significantly enriched protein at recurrence vs baseline. Of 778 pts enrolled in IMmotion010, 752 (97%) had baseline KIM-1 data (high: 300 40%; low: 452 60%). KIM-1–high status was associated with reduced DFS, and pts with KIM-1 high had better DFS with atezo vs pbo (Table). Longitudinal analysis of matched samples showed that in KIM-1–high pts, 9% (12/138) and 26% (36/141) of pts had a ≥30% increase from baseline in KIM-1 levels at Cycle 4 Day 1 with atezo vs pbo, compared with 16% (34/213) and 12% (25/207) in KIM-1-low pts, respectively. A ≥30% KIM-1 increase was associated with worse DFS in both KIM-1–high (atezo HR: 1.68, 95% CI: 0.77, 3.69; pbo HR: 3.53, 95% CI: 2.24, 5.58) and KIM-1–low (atezo HR: 3.56, 95% CI 2.21, 5.75; pbo HR: 3.22, 95% CI: 1.81, 5.70) subgroups. In pts with matched ECL samples (n=103), median KIM-1 levels were higher ( P<0.001) at recurrence (172 pg/mL) than at baseline (79 pg/mL). Conclusions: In IMmotion010, high baseline serum KIM-1 levels were associated with poorer prognosis but improved clinical outcomes with atezo vs pbo. Increased post-tx KIM-1 was associated with worse DFS. These data suggest that circulating KIM-1 may be a non-invasive marker of MRD and disease recurrence and be associated with benefit from atezo in adj RCC. Further investigation of KIM-1 in adj RCC is warranted. Clinical trial information: NCT03024996 . Table: see text