Serum Vitamin D Levels and Peripheral Neuropathy Among Multiple Myeloma Patients

Approximately 10% of myeloma patients present at diagnosis with clinical neuropathy although studies reveal as many as 1/3 may have abnormal electrophysiological examinations. Baseline neuropathic abnormal findings are exacerbated by many myeloma treatments, especially bortezomib, thalidomide, and to a lesser extent lenalidomide. Several studies suggest that vitamin D supplementation may help reduce the symptoms of neuropathy.In this prospective study, we will investigate the relationship between vitamin D and PN among MM patients treated with either bortezomib or thalidomide. The study consists of a screening period of up to 14 days, followed by a single assessment visit to evaluate vitamin D levels, incidence and severity of PN, neuropathic pain, and markers of depression. Patient charts will also be utilized to assess the frequency of skeletal-related events.

Inclusion criteria

• Voluntary written informed consent before performance of any study-related procedure not part of normal medical care, with the understanding that consent may be withdrawn by the subject at any time without prejudice to future medical care.
• Prior diagnosis of multiple myeloma based on standard criteria (Durie 1986)
• Received consecutive, prior treatment for MM with a regimen consisting of at least 16 consecutive weeks of bortezomib or 16 consecutive weeks of thalidomide prior to the Day of Assessment
• The 16 weeks of consecutive treatment must have included at least one of the following doses and schedules:

• Bortezomib: ≥ 1.0 mg/m² dosed 3 or more times per each 4-week period
• Thalidomide: ≥ 50 mg/day dosed daily
• The qualifying regimen may include both bortezomib and thalidomide. However, the above inclusion requirements need only be satisfied by either one of the agents.
• Age ≥18 years at the time of signing the informed consent form
• Able to adhere to the study visit schedule and other protocol requirements

Exclusion criteria

• Plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, monoclonal protein (M-protein) and skin changes (POEMS) syndrome (Bardwick 1980)
• Plasma cell leukemia
• Primary amyloidosis
• Vitamin D level assessment occurring within the 12 months preceding the Day of Assessment
• Vitamin D non-dietary oral supplementation > 1200 IU per day for > 30 total days within the 12 month period preceding the Day of Assessment
• Serious medical or psychiatric illness likely to interfere with participation in this clinical study.
• Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form
• Any condition, including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study.