Peripheral neuropathies are a dose-limiting, disabling, and debilitating side effect of virtually every known class of chemotherapeutic agent, and are referred to as chemotherapy-induced peripheral neuropathies (CIPN) (Seretny et al., 2014). The incidence and severity of CIPN increase as the cumulative dose, frequency of administration, and the number of therapeutic cycles increase. As many as 68% of patients have CIPN when assessed within 30 days of completing treatment. Patients experience paresthesias, dysesthesias (an unpleasant abnormal sensation, whether spontaneous or evoked), hyperalgesia (increased pain from a stimulus that normally provokes pain), allodynia (pain due to a stimulus that does not normally provoke pain), numbness or loss of sensation, or ongoing pain that is burning, lancinating or electric shock-like in nature. CIPN can seriously diminish a patient's quality of life, and can interfere with self-care and activities of daily living. The severity of CIPN may also necessitate reducing the dose of chemotherapeutic agent, delaying the next cycle of chemotherapy, or terminating treatment entirely (Argyriou et al., 2012; Argyriou et al., 2014; Miltenburg et al., 2014; Park et al., 2013).

Nicotinamide adenine dinucleotide (NAD+) is an essential redox coenzyme required for cell viability, basic bioenergetics, and fast axonal transport (Yang and Sauve, 2016). It plays an important role in protection against axonal injury from either mechanical or neurotoxic injury (Araki et al., 2004; Sasaki et al., 2006; Sasaki et al., 2009; Gerdts et al., 2015; Khan et al., 2014; Conforti et al., 2014; Di Stefano et al., 2015). Nicotinamide riboside (NIAGEN®) is a form of vitamin B3 and a precursor in the pathway for synthesis of NAD+ (Bieganowski et al., 2004; Trammell et al., 2016; Chi and Sauve, 2013). Oral administration of NIAGEN® increases levels of NAD+ in the blood, liver, skeletal muscle, and other tissues (Canto et al., 2012; Hamity et al, 2017; Airhart et al., 2017; Martens et al., 2018).

NIAGEN®) has been reported to prevent tactile hypersensitivity and blunt the affective dimension of nociception in a rat model of CIPN (Hamity et al., 2017) It also prevents signs of peripheral neuropathy in a mouse model of diabetes (Trammell et al., 2016) The proposed single-arm pilot phase II study will examine whether daily dosing with NIAGEN®) can prevent the progression of CIPN in persons with stage IV breast cancer or recurrent platinum-resistant ovarian, endometrial, peritoneal, or fallopian tube cancer receiving once weekly infusions of paclitaxel for 12 weeks.

In this study, persons with metastatic breast cancer, platinum-resistant recurrent ovarian, peritoneal, endometrial, or fallopian tube cancer, or platinum-resistant recurrent or metastatic head and neck cancer who are receiving weekly infusions of paclitaxel or nab-paclitaxel and anticipated to survive for at least 3 months will be offered the opportunity to enroll in this study when they develop a peripheral neuropathy of at least grade 1. Persons with peripheral neuropathy of no greater than a grade 2 from prior therapy may also enroll in this study if they are receiving weekly infusions of paclitaxel or nab-paclitaxel. Upon enrollment, health care providers will review the overall severity of the participant's neuropathy and assign a baseline grade. Participants will also complete two short questionnaires that will more specifically score how the peripheral neuropathy interferes with daily functions of living. A small sample of blood will be taken at the completion of the paclitaxel or nab-paclitaxel infusion to measure levels of paclitaxel. The participant will then be sent home with capsules of NIAGEN® to take twice daily. Each week upon return to the clinic a small sample of blood will be taken before the infusion of paclitaxel to measure biomarkers for NIAGEN®, and other samples of blood will be taken to evaluate clinical chemistries, kidney, and liver function. Another sample of blood will be obtained after the paclitaxel or nab-paclitaxel infusion to measure levels of paclitaxel or nab-paclitaxel. The health care provider will meet with the patient each week to score the overall severity of the peripheral neuropathy, and the participant will answer another questionnaire with more specific questions. Once a month, the participant will be asked to fill out a second questionnaire. Participants will take 300 mg/day NIAGEN® in the first week and 1000 mg/day in the subsequent 11 weeks. The study will conclude one week after the 12th infusion of paclitaxel or nab-paclitaxel. Health care providers will contact the participant at various times up to 6 months to monitor their status.

Beginning with completion of the trial by the 10th participant and continuing with each subsequent participant up to 39, we will use a Bayesian statistical approach (Lee and Liu, 2008; i.e. predictive probability) to determine whether NIAGEN® has prevented a worsening of the peripheral neuropathy. This approach we let us make an early determination of futility. We will also determine whether NIAGEN® has decreased the need to delay or diminish the doses of paclitaxel or nab-paclitaxel due to severity of the peripheral neuropathy. The results of this trial will inform the design of a subsequent randomized, placebo-controlled, blinded clinical trial.