Exploring clinical markers of Axon degeneration processes in Chemotherapy-induced peripheral neuropathy among young adults receiving vincristine or paclitaxel.

Background: Approximately 70% of patients receiving neurotoxic chemotherapy (e.g., paclitaxel or vincristine) will develop chemotherapy-induced peripheral neuropathy. Despite the known negative effects of CIPN on physical functioning and chemotherapy dosing, little is known about how to prevent CIPN. The development of efficacious CIPN prevention interventions is hindered by the lack of knowledge surrounding CIPN mechanisms. Nicotinamide adenine dinucleotide (NAD⁺) and cyclic-adenosine diphosphate ribose (cADPR) are potential markers of axon degeneration following neurotoxic chemotherapy, however, such markers have been exclusively measured in preclinical models of chemotherapy-induced peripheral neuropathy (CIPN). The overall objective of this longitudinal, observational study was to determine the association between plasma NAD⁺, cADPR, and ADPR with CIPN severity in young adults receiving vincristine or paclitaxel.

Methods: Young adults (18-39 years old) beginning vincristine or paclitaxel were recruited from Dana-Farber Cancer Institute. Young adults completed the QLQ-CIPN20 sensory and motor subscales and provided a blood sample prior to starting chemotherapy (T1) and at increasing cumulative vincristine (T2: 3-5 mg, T3: 7-9 mg) and paclitaxel (T2: 300-500 mg/m², T3: 700-900 mg/m²) dosages. NAD⁺, cADPR, and ADPR were quantified from plasma using mass spectrometry. Metabolite levels and QLQ-CIPN20 scores over time were compared using mixed-effects linear regression models and/or paired two-sample tests.

Results: Participants (N = 50) were mainly female (88%), white (80%), and receiving paclitaxel (78%). Sensory and motor CIPN severity increased from T1-T3 (p < 0.001). NAD⁺ (p = 0.28), cADPR (p = 0.62), and ADPR (p = 0.005) values decreased, while cADPR/NAD⁺ ratio increased from T1-T3 (p = 0.50). There were no statistically significant associations between NAD + and QLQ-CIPN20 scores over time.

Conclusions: To our knowledge, this is the first study to measure plasma NAD⁺, cADPR, and ADPR among patients receiving neurotoxic chemotherapy. Although, no meaningful changes in NAD⁺, cADPR, or cADPR/NAD⁺ were observed among young adults receiving paclitaxel or vincristine. Future research in an adequately powered sample is needed to explore the clinical utility of biomarkers of axon degeneration among patients receiving neurotoxic chemotherapy to guide mechanistic research and novel CIPN treatments.