Efficacy and safety of dose-escalating lenalidomide and dexamethasone (Rd) for unfit patients with relapsed or refractory multiple myeloma

INTERVENTION: Lenalidomide 10mg daily on day 1‐21 every 28 days, Dexamethasone 20mg a week on day 1, 8, 15, and 22 every 28 days Lenalidomide dose will be escalated from 10mg to 25mg (5mg per cycle) if there are no grade3 hematological toxicities and grade2 non‐hematological toxicities. CONDITION: Unfit patients with relapsed or refractory multiple myeloma PRIMARY OUTCOME: The best response during 1 year from initiation of treatment. SECONDARY OUTCOME: (1) Safety: Hematological toxicity of grade 4, non‐hematological toxicity of grade 3 to 4 ; (2) Continuation rate of treatment; (3) Total dosage of lenalidomide; (4) Overall survival; (5) Progression‐free survival (the rate of patients who are not recognized as having progression or recurrence) INCLUSION CRITERIA: (1) Multiple myeloma diagnosed in the criteria of IMWG (2) Patients aged 20 years old and over with autologous stem cell transplantation ineligible multiple myeloma (3) There is no treatment experience with lenalidomide, relapsed or refractory multiple myeloma patients with medical history over the past 1 regimen (bortezomib intolerance, also including patients paraprotein relapse) (4) Patients who have been judged by the initial dose of the attending physician is necessary loss of lenalidomide (5) Patients with ECOG of Perfomance Status (PS) 0‐3 (6) Patients who keep the function of major organs, it meets the following criteria 1. Neutrophil count 1,000 / mm3 or more 2. Platelets 50,000 / mm3 or more 3. Serum total bilirubin value is less than three times of the facility upper limit of normal 4. Serum AST, ALT value is less than five times of the facility upper limit of normal (7) 6 months or more of survival can be expected (8) Cre