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not part of normal medical care, with the understanding that consent may be withdrawn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.