Background Tumor fibrosis and cancer-associated fibroblast (CAF) activity is becoming a central aspect in cancer biology. The tumor microenvironment (TME) consists mainly of ECM, and biomarkers of tumor fibrosis activity can be quantified from small ECM fragments in serum. An unmet need exists to identify patients with aRCC who are most likely to benefit from treatment with NIVO+IPI.^1,2 Therefore, we explored the prognostic and predictive potential of circulating ECM-associated biomarkers for the first time in patients with aRCC, using samples from the CheckMate 214 trial.

Methods Pretreatment serum was collected, and levels of 17 biomarkers associated with ECM formation, ECM degradation, or immune response (table 1) were assessed using immunoassay-based methods. Biomarker levels were compared between healthy volunteers and patients with aRCC. Associations with International Metastatic RCC Database Consortium (IMDC) risk score, sarcomatoid status, and objective response rate were evaluated. Prognostic and predictive associations were determined retrospectively from patients’ progression-free survival (PFS) and overall survival (OS) outcomes.

Results Clinical (5-year follow-up) and biomarker data were evaluable in 1006 of 1082 treated patients (93%). Statistically significant differences (P < 0.0001) in all 17 biomarkers were observed between healthy individuals and patients with aRCC (table 2). Higher levels of the majority of the biomarkers (all except PRO-C23) were positively correlated with increasing IMDC score (P < 0.01), and 9 biomarkers (including PRO-C3, C6M, and TGFβ-LAP) were increased in patients with sarcomatoid histology (P < 0.05). CPa9-HNE and TGFβ-LAP levels were higher in patients who responded to NIVO+IPI (P < 0.05). In the overall population, higher levels of biomarkers such as C4M, C6M, PRO-C19, TGFβ-LAP, and TUM were associated with shorter PFS and OS (P < 0.05). When comparing treatment arms, higher levels of PRO-C19, PRO-C22, C4M, C6M, CPa9-HNE, VICM, TGFβ-LAP, and TUM were associated with improved PFS with NIVO+IPI (P < 0.05), which is indicative of predictive potential.

Conclusions Biomarkers of ECM formation, degradation, and TGFβ signaling were significantly increased in patients with aRCC compared with healthy individuals, which is indicative of high CAF activity. In patient with aRCC, high levels of ECM biomarkers were associated with poor OS and PFS outcomes. Patients with high ECM remodeling activity responded better to NIVO+IPI than to sunitinib. ECM biomarkers could potentially guide patient selection and/or stratification in future clinical trials. The predictive value of these biomarkers needs to be investigated in prospective clinical trials.

Acknowledgements We would like to thank the CheckMate 214 clinical study teams, as well as Oksana Palyha, Sai Vikram Vemula, Scott Chaslow, Han Chang, Abraham Apfel, Chung-Wei Lee, Jin Yao, Kimberly Gray, Megan Wind-Rotolo, and Daniel Cohen. Editorial support was provided by Rowena Fung, MPhil, of Spark Medica Inc.

Trial Registration Clinicaltrials. gov. NCT02231749.

References

1. Motzer R et al. Nivolumab plus ipilimumab versus sunitinib in advanced renal-cell carcinoma. N Engl J Med 2018;378:1277–1290.

2. Motzer R et al. Biomarker analysis from CheckMate 214: nivolumab plus ipilimumab versus sunitinib in renal cell carcinoma. J Immunother Cancer 2022;10:e004316.

Ethics Approval The trial protocols were approved by site institutional review boards or independent ethics committees and conducted according to Good Clinical Practice guidelines, per the International Conference on Harmonisation. Patients provided written informed consent based on Declaration of Helsinki principles.