Inclusion Criteria:

- One prior allograft from an 8/8 or 7/8 allele matched related or unrelated donor,
received 60 to 90 days prior to initiation of lenalidomide

- Meet the diagnostic criteria of symptomatic myeloma at anytime prior to allogeneic
HCT

- Have high-risk multiple myeloma

- Received ≤ three (3) prior lines of therapy. Prior therapies may include: combination
chemotherapy, monotherapy, lenalidomide and autologous HCT. Localized radiation
therapy does not count as a single line of therapy. Previous progression on
lenalidomide does not exclude participation in the study.

- Received a reduced intensity conditioning regimen

- Received or are receiving a GVHD prophylaxis regimen of a calcineurin inhibitor in
combination with either methotrexate, mycophenolate mofetil (MMF) or sirolimus

- Karnofsky performance score ≥ 80 or ECOG ≤ 2

- There must be at least 50% donor chimerism and no evidence of falling donor chimerism
within 1 month of enrollment

- Laboratory test results within range, within 14 days prior to initiation of
lenalidomide

- All study participants must be registered into the mandatory RevAssist® program, and
be willing and able to comply with the requirements of RevAssist®.

Exclusion Criteria:

- Disease progression at time of study entry

- Patients with any grade III-IV GVHD at the time of study entry

- Patients requiring additional immunosuppressive therapy to control acute GVHD other
than corticosteroids and immunosuppressive agents used for prophylaxis.

- Concomitant use of other investigational agents

- Patients who have received donor lymphocyte infusions

- Active CNS malignancy

- Uncontrolled bacterial, viral, or fungal infections

- Prior malignancies except resected basal cell carcinoma or treated cervical carcinoma
in situ < 5 years from study entry.

- Known hypersensitivity or desquamating rash to either thalidomide or lenalidomide.

- Known positive for HIV or active infectious hepatitis.

- Women who are pregnant or breastfeeding.

- New York Heart Association (NYHA) Class III or IV heart failure, uncontrolled angina,
severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of
acute ischemia or active conduction system abnormalities.