Neurofilament Light Chain: A Potential Biomarker for Chemotherapy-Induced Peripheral Neuropathy in Pediatric and Adolescent Young Adults with Leukemia or Lymphoma

Introduction: Chemotherapy-induced peripheral neuropathy (CIPN) is a common and dose-limiting toxicity in child, adolescent, and young adult (CAYA) oncology populations. Despite its clinical impact, objective biomarkers for early detection and monitoring remain limited. Neurofilament light chain (NfL), a marker of axonal injury, has emerged as a potential circulating biomarker of CIPN in adults and potentially for CAYAs. This pilot study evaluates the association between NfL and patient-reported CIPN severity in CAYAs. Methods: We conducted a prospective pilot study of 26 patients with acute lymphoblastic leukemia or lymphoma. CIPN was assessed using FACT-GOG/NTx scores. Linear mixed-effects models evaluated associations between NfL and neuropathy over time, adjusting for age and time from baseline. Logistic mixed models assessed the relationship between NfL and clinically significant neuropathy (FACT-GOG/NTx ≤ 40). Results: NfL was significantly associated with worsening neuropathy. A 50-unit increase in NfL corresponded to a 1.1-point decrease in FACT-GOG/NTx score (p < 0.001). Each doubling of NfL was associated with a 0.61-point decrease in FACT-GOG/NTx (p < 0.001). Higher NfL levels increased odds of neuropathy (OR 4.62, p < 0.001). Associations were strongest in leukemia patients and not observed in Hodgkin lymphoma when separately analyzed. Conclusions: This pilot study demonstrates that circulating NfL correlates with patient-reported neuropathy severity, supporting its role as a potential biomarker for CIPN in CAYAs. Differences between leukemia and lymphoma cohorts may reflect treatment-specific neurotoxicity patterns and should be validated in larger prospective studies. Limitations include small sample size, heterogeneity, and limited power for subgroup analyses. If validated, NfL could be incorporated into routine toxicity monitoring to identify patients at highest risk for progressive CIPN, enabling earlier supportive care interventions, referral to rehabilitation services, or enrollment in biomarker-guided prevention and treatment trials before irreversible nerve injury occurs.