What is the recommended diagnostic workup and first‑line treatment for multiple myeloma, including options for transplant‑eligible and transplant‑ineligible patients?

Multiple Myeloma: Diagnostic Workup and First-Line Treatment

Diagnostic Workup

Whole-body low-dose CT is now the preferred imaging modality for detecting bone disease in multiple myeloma, replacing traditional skeletal surveys. 1

Essential Laboratory Testing

• Serum protein electrophoresis (SPEP) with immunofixation to detect and characterize the monoclonal protein 2, 3
• 24-hour urine collection for protein electrophoresis and immunofixation—random urine samples are insufficient 3
• Serum free light chain assay with kappa/lambda ratio, particularly critical when standard SPEP is negative 3
• Quantification of IgG, IgA, and IgM immunoglobulins by nephelometry 3
• Complete blood count, serum creatinine, calcium, LDH, and β2-microglobulin for staging and risk assessment 2

Bone Marrow Evaluation

• Bone marrow aspiration and biopsy to quantify plasma cell infiltration (≥10% clonal plasma cells required for diagnosis) 2, 4
• Cytogenetic analysis by FISH to detect high-risk features including del(17p), t(4;14), t(14;16), t(14;20), gain 1q, del 1p, or p53 mutation 2, 4

Imaging Studies

• Whole-body low-dose CT detects up to 60% more lesions than skeletal surveys and is superior for spine and pelvis evaluation 1
• FDG-PET/CT or MRI may be used as alternatives at baseline, particularly useful for extramedullary disease, nonsecretory myeloma, or equivocal lesions 1
• Focused skull and rib radiographs may still be needed as these areas are not well visualized by CT or MRI 1

Risk Stratification

• Revised International Staging System (R-ISS) combines β2-microglobulin, albumin, LDH levels, and high-risk cytogenetics (del(17p), t(4;14), t(14;16)) 2, 4
• Double-hit myeloma is defined by presence of any two high-risk factors; triple-hit myeloma by three or more 4

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First-Line Treatment for Transplant-Eligible Patients

For transplant-eligible patients, induction therapy with daratumumab plus bortezomib, lenalidomide, and dexamethasone (Dara-VRd) followed by autologous stem cell transplantation represents the current standard of care. 4, 5

Induction Therapy

• VRd (bortezomib, lenalidomide, dexamethasone) for 3-4 cycles is standard for transplant-eligible patients 5
• Dara-VRd (daratumumab plus VRd) is preferred for high-risk patients with adverse cytogenetics 5
• Avoid alkylating agents during induction to prevent stem cell damage 1

Consolidation

• High-dose melphalan 200 mg/m² followed by autologous stem cell transplantation (ASCT) 6, 2, 3
• Peripheral blood progenitor cells are preferred over bone marrow as the stem cell source 6
• Selected standard-risk patients may collect stem cells and delay transplant until first relapse 5

Maintenance Therapy

• Lenalidomide maintenance for standard-risk patients to prolong progression-free survival 2, 5
• Bortezomib plus lenalidomide maintenance is required for high-risk myeloma 5

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First-Line Treatment for Transplant-Ineligible Patients

For transplant-ineligible patients, daratumumab, lenalidomide, and dexamethasone (DRd) continued until progression is the preferred regimen. 4, 5

Primary Treatment Options

• DRd (daratumumab, lenalidomide, dexamethasone) until progression is the preferred option for older adults 7
• VRd for 8-12 cycles followed by lenalidomide maintenance is an alternative 5
• Bortezomib/melphalan/prednisone (VMP): bortezomib 1.3 mg/m² subcutaneously days 1,8,15,22; melphalan 9 mg/m² orally days 1-4; prednisone 60 mg/m² orally days 1-4; repeated every 35 days 2
• Lenalidomide/low-dose dexamethasone (Rd): lenalidomide 25 mg orally days 1-21; dexamethasone 40 mg orally days 1,8,15,22; repeated every 28 days 2

Frailty Assessment

• Functional status, comorbidities, and activities of daily living should guide treatment intensity—frail patients experience higher nonhematologic toxicity and treatment discontinuation 1

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Supportive Care Measures

Bone Protection

• Long-term bisphosphonates (oral or IV) reduce skeletal events and should be administered to all patients with bone disease 1, 6, 2

Renal Protection

• Aggressive IV hydration with normal saline at 150-200 mL/hour to achieve urine output >100 mL/hour in patients with renal insufficiency or high tumor burden 2
• Rasburicase 0.2 mg/kg IV as single dose for tumor lysis syndrome prophylaxis in high-risk patients 2
• Immediate bortezomib-based chemotherapy should not be delayed for extended periods in patients with renal involvement 2

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Response Monitoring

• M-protein assessment (serum/urine electrophoresis) after 1-2 cycles initially, then every other cycle during active treatment 2
• Complete response requires bone marrow aspiration showing <5% plasma cells and negative immunofixation 1, 6
• Very good partial response (VGPR) is defined by disappearance of M-component or >90% reduction with positive immunofixation 1
• Use the same free light chain assay for serial measurements to ensure accurate relative quantification 6

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Critical Pitfalls to Avoid

• Do not treat smoldering (asymptomatic) myeloma—observation with monitoring at 3-6 month intervals is appropriate 6, 2
• Avoid multiagent chemotherapy in elderly patients—it has not proven superior and may be inferior 6
• Do not use VAD (vincristine, adriamycin, dexamethasone) as it is no longer standard for induction or relapse 1
• Ensure thromboprophylaxis when using thalidomide-based regimens, particularly in patients with high tumor burden or history of thrombosis 1