Antithymocyte Globulin and Sirolimus in Treating Patients With Relapsed Multiple Myeloma

DISEASE CHARACTERISTICS:

• Previously diagnosed multiple myeloma (MM) based on standard criteria
• Soft tissue (not bone only) plasmacytomas allowed
• Measurable disease, meeting both of the following criteria:
• Monoclonal population of plasma cell in the bone marrow
• Quantifiable serum and/or urine monoclonal protein (i.e., generally, but not exclusively, IgG > 1 g/dL, IgA > 0.5 g/dL, or urine light-chain excretion ≥ 200 mg/24 hours)
• Steroid-refractory disease, defined as less than a minimum response to prior high-dose glucocorticoid therapy
• Minimal response requires all of the following criteria:
• 25-49% reduction in the level of serum monoclonal paraprotein maintained for ≥ 6 weeks
• 50-89% reduction in 24-hour urinary light-chain excretion, but still > 200 mg/24 hours, maintained for ≥ 6 weeks
• 25-49% reduction in the size of soft tissue plasmacytomas (clinically or by CT scan or MRI)
• No increase in size or number of lytic bone lesions
• High-dose glucocorticoid therapy defined as 480 mg dexamethasone (or equivalent) alone or as part of a vincristine, doxorubicin, and dexamethasone regimen
• Must have undergone autologous transplantation OR received ≥ 2 conventional lines of therapy
• Currently requiring therapy for progressive disease, as indicated by any of the following criteria:
• 25% increase in paraprotein
• Development of new or progression of pre-existing lytic bone lesions or soft tissue plasmacytomas
• Hypercalcemia not attributable to any other cause
• Relapse from complete remission
• No nonsecretory MM

PATIENT CHARACTERISTICS:

• Zubrod performance status 0-2
• 3-4 allowed if, in the opinion of the investigator, secondary to MM-related bone pain
• Life expectancy ≥ 3 months
• Creatinine ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 2.5 times ULN
• Bilirubin ≤ 1.5 times ULN
• Calcium < 14 mg/dL
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• HIV negative
• Hepatitis B surface antigen and hepatitis C antibody negative
• No known history of allergy to rabbit proteins
• No history of cardiac amyloidosis
• No poorly controlled hypertension, diabetes mellitus, coronary artery disease, or other serious medical or psychiatric illness
• No myocardial infarction within the past 6 weeks
• No New York Heart Association class III or IV heart failure
• No uncontrolled angina
• No severe uncontrolled ventricular arrhythmias
• No evidence of acute ischemia or active conduction system abnormality by electrocardiogram
• No active systemic infection requiring treatment unless adequately controlled with appropriate antimicrobial therapy (e.g., treated central line infection)
• No acute viral illness
• No pathologic fractures or symptomatic hyperviscosity
• No other prior malignancy except adequately treated basal cell or squamous cell skin cancer, cervical cancer in situ, or any other cancer with a disease-free status for ≥ 3 years

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 8 weeks since prior immunotherapy or antibody therapy
• At least 4 weeks since prior major surgery (except for kyphoplasty)
• At least 3 weeks since prior conventional chemotherapy or radiotherapy for MM
• At least 3 weeks since prior bortezomib, thalidomide, or clarithromycin for MM
• No prior anti-thymocyte globulin
• No concurrent radiotherapy
• No other concurrent antineoplastic therapy with known activity against MM, including clarithromycin
• No other concurrent investigational agents