11.3 Multiple Myeloma & Plasma Cell Dyscrasias
Key Takeaways
- Multiple Myeloma is diagnosed by >=10% clonal bone marrow plasma cells (or biopsy-proven plasmacytoma) plus CRAB features (Hypercalcemia, Renal failure, Anemia, Bone lesions) or SLiM high-risk biomarkers (>=60% plasma cells, involved/uninvolved FLC ratio >=100, >1 focal MRI bone lesion).
- Frontline quadruplet therapy with Daratumumab + Bortezomib + Lenalidomide + Dexamethasone (D-VRd per GRIFFIN/PERSEUS) is the standard of care for transplant-eligible myeloma, followed by high-dose melphalan conditioned ASCT and lenalidomide maintenance; transplant-ineligible patients receive Daratumumab + Lenalidomide + Dexamethasone (D-Rd per MAIA).
- Immunomodulatory drugs (IMiDs: lenalidomide, pomalidomide) mandate strict REMS participation, risk-stratified thromboprophylaxis (aspirin for low-risk; therapeutic LMWH or DOAC for high-risk combinations), and dose adjustments for renal clearance.
- Proteasome inhibitors demand signature toxicity monitoring: bortezomib requires subcutaneous administration and mandatory acyclovir/valacyclovir prophylaxis to prevent Herpes Zoster reactivation; carfilzomib requires blood pressure control and cardiovascular monitoring for heart failure and ischemic events.
- Relapsed/refractory myeloma has been revolutionized by BCMA-directed CAR T-cell therapies (ciltacabtagene autoleucel, idecabtagene vicleucel), BCMA bispecific T-cell engagers (teclistamab, elranatamab with IVIG support for hypogammaglobulinemia), and the GPRC5D bispecific talquetamab (requiring management of oral dysgeusia, dysphagia, skin desquamation, and nail dystrophy).
11.3 Multiple Myeloma & Plasma Cell Dyscrasias
Multiple Myeloma is a clonal plasma cell neoplasm originating in the bone marrow that secretes monoclonal immunoglobulins (M-protein / paraprotein) or free light chains (kappa or lambda). The unregulated expansion of these malignant plasma cells disrupts normal hematopoiesis, stimulates osteoclast-mediated bone destruction, causes tubular nephropathy, and impairs humoral immunity.
Over the past two decades, the treatment paradigm for myeloma has transformed dramatically from melphalan-prednisone alkylator therapy into multi-target combinations of Immunomodulatory Drugs (IMiDs), Proteasome Inhibitors (PIs), Anti-CD38 Monoclonal Antibodies, BCMA- and GPRC5D-directed Bispecific Antibodies, and Autologous CAR T-Cell Therapies.
1. Diagnostic Criteria, Staging & Risk Stratification
According to the International Myeloma Working Group (IMWG), diagnosis requires >= 10% clonal bone marrow plasma cells (or biopsy-proven plasmacytoma) PLUS at least one of the classic CRAB features or SLiM biomarkers of malignancy:
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| IMWG MULTIPLE MYELOMA DIAGNOSTIC CRITERIA |
| |
| [CLASSIC CRAB FEATURES (End-Organ Damage)] |
| - **C** (Hypercalcemia): Serum Calcium > 11 mg/dL (or > 1 mg/dL above ULN)|
| - **R** (Renal Insufficiency): Serum Creatinine > 2 mg/dL or CrCl < 40 mL/|
| - **A** (Anemia): Hemoglobin < 10 g/dL (or > 2 g/dL below lower limit) |
| - **B** (Bone Lesions): >= 1 osteolytic lesion on skeletal radiography, |
| CT, or PET-CT |
| |
| [SLiM BIOMARKERS OF MALIGNANCY (>= 80% 2-Year Progression Risk)] |
| - **S** (Sixty Percent): **>= 60% clonal bone marrow plasma cells** |
| - **Li** (Light Chain Ratio): Involved-to-uninvolved serum **Free Light |
| Chain (FLC) ratio >= 100** (involved >= 100) |
| - **M** (MRI Focal Lesions): **> 1 focal lesion (>= 5 mm)** on MRI scans |
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Revised International Staging System (R-ISS & R2-ISS)
Prognosis is governed by tumor burden (serum beta-2 microglobulin and albumin), serum lactate dehydrogenase (LDH), and high-risk chromosomal abnormalities detected by interphase FISH:
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| R-ISS STAGING & HIGH-RISK CYTOGENETICS |
| |
| [HIGH-RISK CYTOGENETICS BY FISH] |
| - **del(17p) / TP53 deletion** (associated with aggressive biology / EMD) |
| - **t(4;14)(p16;q32)** (FGFR3 / MMSET deregulation) |
| - **t(14;16)(q32;q23)** (c-MAF deregulation) |
| - **t(14;20)(q32;q11)** (MAFB deregulation) |
| - **1q21 Gain / Amplification (+1q21 / amp1q21)** |
| |
| [R-ISS STAGES] |
| - **Stage I:** ISS Stage I (Serum beta-2 microglobulin < 3.5 mg/L AND |
| Albumin >= 3.5 g/dL) + Standard-risk FISH + Normal Serum LDH |
| - **Stage III:** ISS Stage III (Serum beta-2 microglobulin >= 5.5 mg/L) |
| AND EITHER High-risk FISH OR Elevated Serum LDH |
| - **Stage II:** All other combinations not fitting Stage I or III |
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2. Frontline Induction Paradigms: Quadruplets vs Triplets
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| FRONTLINE MULTIPLE MYELOMA ALGORITHM |
| |
| NEWLY DIAGNOSED ACTIVE MULTIPLE MYELOMA |
| | |
| Assess ASCT Eligibility (Age, Frailty, Organ Fn) |
| | |
| +-------------------------+-------------------------+ |
| | | |
| v v |
| [TRANSPLANT-ELIGIBLE] [TRANSPLANT-INELIGIBLE]|
| - **D-VRd Quadruplet Induction** (4-6 cycles) - **D-Rd Triplet** |
| * Daratumumab SC 1800 mg weekly/Q3W * Daratumumab SC |
| * Bortezomib 1.3 mg/m2 SC D1,4,8,11 * Lenalidomide 25 mg |
| * Lenalidomide 25 mg PO D1-14 Q21D * Dexamethasone 40 mg|
| * Dexamethasone 20-40 mg weekly - (MAIA Trial: median |
| * (GRIFFIN & PERSEUS Trials: superior uMRD) PFS > 61.9 months!) |
| | - Alternative (Frail): |
| v * VRd-Lite |
| [HIGH-DOSE MELPHALAN (200 mg/m2) + ASCT] |
| | |
| v |
| [POST-ASCT MAINTENANCE THERAPY] |
| - Standard Risk: **Lenalidomide 10-15 mg PO daily (D1-21 Q28D or cont.)**|
| (CALGB 10010 meta-analysis: +2.5 year overall survival benefit) |
| - High Risk: **Bortezomib Q2W** OR **Daratumumab + Lenalidomide** |
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3. Core Myeloma Drug Classes: Mechanisms, Toxicities & Pharmacist Interventions
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| CORE MYELOMA PHARMACOTHERAPY MASTER REFERENCE |
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| 1. IMMUNOMODULATORY DRUGS (IMiDs: Lenalidomide, Pomalidomide, Thalidomide) |
| - Mechanism: Bind **CEREBLON (CRBN)**, part of the CRL4-CRBN E3 ubiquitin|
| ligase complex -> triggers proteasomal degradation of Ikaros (IKZF1) |
| and Aiolos (IKZF3) -> downregulates IRF4 and MYC, activates T/NK cells.|
| - **Teratogenicity:** Strict REMS program mandate (Lenalidomide REMS, |
| Pomalyst REMS); mandatory 2 forms of contraception, 28-day supply limit|
| - **Venous Thromboembolism (VTE):** High risk when combined with steroids|
| - **Renal Dosing (Lenalidomide is renally cleared):** |
| * CrCl 30-50 mL/min: 10 mg PO daily |
| * CrCl < 30 mL/min: 15 mg PO Q48H or 5 mg daily |
| * Hemodialysis: 5 mg PO daily administered post-dialysis |
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| 2. PROTEASOME INHIBITORS (PIs: Bortezomib, Carfilzomib, Ixazomib) |
| - Mechanism: Inhibit 20S core of 26S proteasome -> unfolded protein |
| response, ER stress, apoptosis; downregulates NF-kappaB. |
| - **Bortezomib (Velcade):** Reversible boronate inhibitor. |
| * Toxicity: Peripheral neuropathy (PN: 10% SC vs 40% IV). Use SC route!|
| * Mandatory Prophylaxis: **Acyclovir 400 mg PO BID** or Valacyclovir |
| 500 mg daily for **Herpes Zoster (VZV) reactivation** prevention. |
| - **Carfilzomib (Kyprolis):** Irreversible epoxyketone inhibitor. |
| * Toxicity: **Cardiotoxicity / Heart Failure (8-10%)**, Hypertension |
| (20-25%), Pulmonary Hypertension, Dyspnea, Microangiopathy. |
| * Pharmacist Mandate: Monitor BP; avoid excessive IV pre-hydration. |
| - **Ixazomib (Ninlaro):** Oral boronate PI. Take on empty stomach (1h b/ |
| 2h after food); GI toxicity, thrombocytopenia, rash. |
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| 3. ANTI-CD38 MONOCLONAL ANTIBODIES (Daratumumab, Isatuximab) |
| - Mechanism: Target CD38 surface glycoprotein; CDC, ADCC, ADCP, apoptosis|
| - **Daratumumab (Darzalex / Darzalex Faspro [1800 mg SC + Hyaluronidase])|
| - **BLOOD BANK INTERFERENCE (CRITICAL BOARD PEARL):** |
| * Binds CD38 on reagent red blood cells, causing a **FALSE-POSITIVE |
| INDIRECT COOMBS TEST (Indirect Antiglobulin Test [IAT])** for up to |
| 6 months post-treatment! |
| * PHARMACY MANDATE: Obtain **Baseline Type & Screen with Extended Red |
| Blood Cell Phenotyping/Genotyping PRIOR TO FIRST DOSE** of anti-CD38.|
| * Inform blood bank to treat reagent RBCs with **Dithiothreitol (DTT)**|
| to denature surface CD38 (note: DTT destroys Kell [K] antigens). |
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IMiD-Associated VTE Risk Assessment & Pharmacotherapy
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| IMWG / ASCO THROMBOPROPHYLAXIS ALGORITHM |
| |
| PATIENT RECEIVING IMiD (Lenalidomide / Pomalidomide) + CORTICOSTEROID |
| | |
| Calculate VTE Risk Factors (SAVED or IMPEDE Score) |
| - Risk Factors: Prior VTE, BMI >= 30, High-Dose Dexamethasone (>=480 mg/m)|
| Concurrent Doxorubicin, Immobilization, Hyperviscosity, Renal failure |
| | |
| +-------------------------+-------------------------+ |
| | | |
| v (0 to 1 Individual Risk Factor) v (>=2 Factors) |
| [LOW VTE RISK] [HIGH VTE RISK] |
| - **Aspirin 81 mg to 325 mg PO daily** - **LMWH (Enoxaparin |
| 40 mg SC daily)** OR |
| - **DOAC (Apixaban |
| 2.5 mg PO BID or |
| Rivaroxaban 10 mg)** |
| - **Warfarin (INR 2-3)**
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4. Relapsed/Refractory Myeloma: Biologics, Bispecifics & CAR T-Cell Therapy
For patients progressing on frontline PIs, IMiDs, and anti-CD38 antibodies (triple-class refractory disease), recent breakthroughs have transformed outcomes:
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| NOVEL TARGETED PARADIGMS IN RELAPSED / REFRACTORY MM |
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| 1. BCMA-DIRECTED CAR T-CELL THERAPIES |
| - **Ciltacabtagene autoleucel (Cilta-cel; Carvykti):** CARTITUDE-4 trial |
| (Binds 2 distinct BCMA epitopes). Unprecedented ORR >95%, deep CRs. |
| * Signature Toxicities: CRS, ICANS, Delayed Movement / Parkinsonism. |
| - **Idecabtagene vicleucel (Ide-cel; Abecma):** KarMMa-3 trial. |
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| 2. BCMA-DIRECTED BISPECIFIC ANTIBODIES (BiTEs) |
| - **Teclistamab (Tecvayli):** Binds BCMA on myeloma + CD3 on T cells. |
| * Subcutaneous step-up dosing: 0.06 mg/kg -> 0.3 mg/kg -> 1.5 mg/kg. |
| - **Elranatamab (Elrexfio):** Subcutaneous step-up dosing to 76 mg QW. |
| - PHARMACY MANDATE FOR BCMA BISPECIFICS: |
| * **Severe Hypogammaglobulinemia (IgG < 400 mg/dL):** Mandatory monthly|
| **Intravenous Immunoglobulin (IVIG 0.4-0.5 g/kg)** replacement to |
| prevent catastrophic opportunistic infections. |
| * PJP prophylaxis (TMP-SMX) and anti-herpetic prophylaxis (Acyclovir). |
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| 3. GPRC5D-DIRECTED BISPECIFIC ANTIBODY |
| - **Talquetamab (Talvey):** Binds **G Protein-Coupled Receptor Family C |
| Group 5 Member D (GPRC5D)** on plasma cells + CD3 on T cells. |
| - MonumenTAL-1 trial: Highly effective post-BCMA therapy failure! |
| - SIGNATURE ON-TARGET / OFF-TUMOR TOXICITIES: |
| * **Oral Toxicity (Dysgeusia / Ageusia / Dry Mouth in 70-80%):** Lead |
| to weight loss; manage with saliva stimulants, ice chips, zinc. |
| * **Skin & Nail Toxicities (Palmar-plantar desquamation, Nail |
| Dystrophy / Onycholysis in 50-60%):** Treat with high-potency topical|
| corticosteroids and ammonium lactate / urea creams. |
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| 4. NUCLEAR EXPORT INHIBITOR: SELINEXOR (Xpovio) |
| - Mechanism: Selective Inhibitor of Nuclear Export (SINE); inhibits |
| **Exportin-1 (XPO1)**, forcing nuclear retention of p53, IkappaB, Rb. |
| - Dosing: 100 mg PO weekly (+ Bortezomib/Dex per BOSTON trial). |
| - PHARMACY MANDATE: **Severe Nausea, Anorexia & Hyponatremia** |
| * Mandatory Prophylaxis: **5-HT3 antagonist (Ondansetron)** PLUS |
| **Olanzapine 2.5 to 5 mg PO daily** at bedtime. |
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| 5. BCL-2 INHIBITOR IN t(11;14) MYELOMA: VENETOCLAX |
| - Translocation t(11;14)(q13;q32) creates high BCL-2 to MCL-1 ratio. |
| - Venetoclax 400-800 mg PO daily combined with dexamethasone +/- PI |
| yields remarkable >80% response rates specifically in t(11;14) disease!|
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5. Supportive Care in Myeloma: Bone Health, Renal Care & AL Amyloidosis
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| SUPPORTIVE PHARMACOTHERAPY & AL AMYLOIDOSIS PROTOCOLS |
| |
| 1. BONE-MODIFYING AGENTS (BMAs) IN MULTIPLE MYELOMA |
| - Indication: All active myeloma patients requiring therapy, regardless|
| of whether lytic bone lesions are visible on baseline imaging. |
| - **Zoledronic Acid (4 mg IV Q3-4W):** Reduce dose for baseline renal |
| impairment (CrCl 50-60: 3.5 mg; 40-49: 3.3 mg; 30-39: 3.0 mg). Avoid|
| if CrCl < 30 mL/min. |
| - **Denosumab (120 mg SC Q4W per Raje et al. Lancet Oncol 2018):** |
| * Preferred agent in renal insufficiency (CrCl < 30 mL/min or ESRD). |
| * Does NOT require renal dose adjustment. |
| * CRITICAL PEARL: Severe **Hypocalcemia Risk** and **Rebound Fractures|
| upon Abrupt Discontinuation** (consolidate with bisphosphonate). |
| - Osteonecrosis of the Jaw (ONJ) Prevention: Mandatory baseline dental |
| exam; hold BMAs prior to invasive dental procedures. |
| |
| 2. AL AMYLOIDOSIS (LIGHT CHAIN AMYLOIDOSIS) |
| - Pathophysiology: Clonal plasma cells produce misfolded light chains |
| that deposit as amyloid fibrils in heart (restrictive cardiomyopathy)|
| kidneys (nephrotic syndrome), liver, and autonomic nervous system. |
| - Frontline Standard (ANDROMEDA Trial: Kastritis et al. NEJM 2021): |
| **Daratumumab SC + CyBorD (Cyclophosphamide + Bortezomib + Dex)** |
| * Achieves rapid, deep hematologic complete response and organ |
| reversal (cardiac and renal response). |
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Master Multiple Myeloma Pharmacotherapy Summary
| Clinical Setting | Standard Regimens | Key Toxicities & Boxed Warnings | Essential Pharmacist Action Points | | :--- | :--- | :--- | :--- | :--- | | Frontline Transplant-Eligible | D-VRd -> ASCT -> Lenalidomide maintenance | Neuropathy (Bortezomib), VTE/cytopenias (Lenalidomide), Coombs interference (Dara) | Baseline extended red blood cell phenotyping; Acyclovir for VZV; Enoxaparin/Aspirin for VTE; SC bortezomib. | | Frontline Transplant-Ineligible | D-Rd (MAIA) or VRd-Lite | Fatigue, Diarrhea, Pneumonia, Neutropenia, VTE | Monthly IVIG if IgG <400 with infections; renal dose adjustment for Lenalidomide; VTE prophylaxis. | | Relapsed (Triple-Class Exposed) | Teclistamab / Elranatamab (BCMA BiTE) | CRS, ICANS, Severe Neutropenia, Opportunistic Sepsis | Step-up inpatient dosing; Dexamethasone premedication; monthly IVIG replacement; PJP/VZV prophylaxis. | | Relapsed (GPRC5D-Targeted) | Talquetamab (GPRC5D BiTE) | Dysgeusia/Ageusia, Dysphagia, Weight Loss, Palmar-plantar desquamation, Nail loss | Counsel on saliva stimulants, mouth ice chips, zinc; topical urea/steroid creams for skin/nails. | | Relapsed (t(11;14) Translocation) | Venetoclax + Dexamethasone | Nausea, Diarrhea, Neutropenia, Sepsis | Biomarker testing for t(11;14) by FISH; prophylactic antimicrobials; monitor CBC. | | Bone Disease Management | Zoledronic Acid OR Denosumab | Renal tubular necrosis (Zoledronic), Severe Hypocalcemia (Denosumab), ONJ | Calcium + Vitamin D co-prescription; dental clearance; use Denosumab if CrCl < 30 mL/min. | | AL Amyloidosis | Dara-CyBorD (ANDROMEDA) | Fluid retention, Arrhythmias, Neuropathy, Hypotension | Monitor NT-proBNP and troponin; avoid rapid IV hydration due to amyloid cardiomyopathy. |
A 61-year-old male with newly diagnosed symptomatic IgG kappa multiple myeloma (Stage II, R-ISS) is preparing to initiate frontline induction chemoimmunotherapy with Daratumumab, Bortezomib, Lenalidomide, and Dexamethasone (D-VRd). The patient has a baseline history of hypertension and a prior deep vein thrombosis 3 years ago following knee arthroscopy. Baseline laboratory testing demonstrates: Serum Creatinine 1.1 mg/dL, CrCl 82 mL/min, and Hemoglobin 10.1 g/dL. Which of the following combinations of clinical pharmacist interventions is required prior to and during the initiation of this regimen?
A 67-year-old female with relapsed/refractory multiple myeloma refractory to bortezomib, carfilzomib, lenalidomide, pomalidomide, and daratumumab initiates therapy with the GPRC5D-directed bispecific T-cell engager talquetamab per the standard step-up dosing schedule. After 6 weeks of maintenance dosing, she achieves a partial response but presents to the clinic complaining of severe loss of taste (ageusia), profound dry mouth, difficulty swallowing dry foods, painful peeling and erythema of her palms and soles, and softening with ridging of her fingernails (onycholysis). Which of the following explains the pathophysiology of these adverse events, and what is the most appropriate pharmacist-led management strategy?
A 74-year-old male with newly diagnosed multiple myeloma presents with extensive lytic lesions throughout his spine, pelvis, and femurs. His baseline laboratory profile shows: Serum Creatinine 2.9 mg/dL, estimated CrCl 22 mL/min, Serum Calcium 10.8 mg/dL, and Albumin 3.2 g/dL. The oncology team wants to initiate a bone-modifying agent to prevent skeletal-related events (pathologic fractures, spinal cord compression, radiation to bone). Which of the following recommendations should the oncology clinical pharmacist provide regarding the selection and safety of bone-modifying therapy for this patient?
A 56-year-old male with relapsed/refractory multiple myeloma receives teclistamab (BCMA-directed bispecific antibody) following step-up dosing. At Month 4 of therapy, the patient has achieved a complete response (negative immunofixation and normal serum free light chain ratio). Routine laboratory evaluation reveals: IgG 280 mg/dL (profoundly decreased; reference 700–1,600 mg/dL), IgA < 20 mg/dL, and IgM < 15 mg/dL. He reports two recent episodes of upper respiratory tract bacterial infections treated with outpatient amoxicillin-clavulanate. According to consensus guidelines and pharmacovigilance data, what is the most appropriate clinical pharmacist-led management strategy for this patient?