📋 Key Information Summary
- Multiple myeloma is a clonal plasma cell malignancy characterised by CRAB criteria: Calcaemia (hypercalcaemia), Renal insufficiency, Anaemia, and Bone lesions — these represent end-organ damage and mandate treatment initiation.
- The International Staging System (ISS) and Revised ISS (R-ISS) incorporating β₂-microglobulin, albumin, LDH, and cytogenetic risk stratify patients into standard-, intermediate-, and high-risk groups.
- Key investigations include serum protein electrophoresis (SPEP) with immunofixation, serum free light chain (sFLC) assay, 24-hour urine Bence Jones protein, bone marrow biopsy with FISH/cytogenetics, and whole-body low-dose CT or PET-CT.
- Induction therapy in transplant-eligible patients typically comprises a bortezomib-based triplet (e.g., bortezomib–lenalidomide–dexamethasone [VRd]) followed by autologous stem cell transplantation (ASCT).
- In transplant-ineligible patients, VRd-lite (modified dosing) or daratumumab-containing regimens (D-VMP, DRd) are first-line per Australian guidelines.
- Proteasome inhibitors (bortezomib, carfilzomib) and immunomodulatory drugs (lenalidomide, pomalidomide) form the backbone of myeloma therapy; monoclonal antibodies (daratumumab, isatuximab) are increasingly incorporated.
- Bortezomib subcutaneous administration reduces peripheral neuropathy; schedule weekly (days 1, 8, 15) rather than twice-weekly to improve tolerability.
- Lenalidomide is PBS-listed as Authority Required for maintenance post-ASCT and relapsed/refractory myeloma; dose adjustment is essential for renal impairment (CrCl <60 mL/min).
- Bisphosphonate therapy (zoledronic acid or pamidronate) is indicated for all patients with myeloma bone disease; denosumab is an alternative if renal impairment precludes bisphosphonates.
- Tumour lysis syndrome prophylaxis and thromboprophylaxis with lenalidomide-containing regimens are critical supportive measures.
- Aboriginal and Torres Strait Islander peoples may present with later-stage disease and have higher rates of renal complications; culturally safe, community-based follow-up improves outcomes.
- Smouldering (asymptomatic) myeloma requires monitoring only unless high-risk features are present; the 20/2/20 criteria help identify candidates for early intervention.
Introduction & Australian Epidemiology
Multiple myeloma is a malignant neoplasm of terminally differentiated B-lymphocytes (plasma cells) that accumulate in the bone marrow, producing monoclonal immunoglobulin (M-protein) and/or free light chains. It accounts for approximately 10% of all haematological malignancies and remains incurable in the majority of patients, although recent therapeutic advances have substantially improved survival.
In Australia, myeloma is the second most common haematological malignancy. The Australian Institute of Health and Welfare (AIHW) reports approximately 1,800–2,000 new diagnoses annually, with an age-standardised incidence rate of around 7.5 per 100,000. Median age at diagnosis is 69 years, with a slight male predominance (1.4:1). Five-year relative survival has improved from approximately 30% in the early 2000s to over 55% in recent cohorts, attributable to proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and improved supportive care.
Aboriginal and Torres Strait Islander Australians have a higher incidence of myeloma and are more likely to present with advanced disease, renal impairment, and hypercalcaemia. Barriers to timely diagnosis and specialist referral contribute to these disparities.
The diagnostic and therapeutic landscape continues to evolve with the introduction of chimeric antigen receptor (CAR) T-cell therapies (ide-cel, cilta-cel) and bispecific antibodies (teclistamab, elranatamab) for relapsed/refractory disease, though access in Australia remains largely through clinical trials and special access schemes.
Pathogenesis & CRAB Criteria
Pathogenesis
Multiple myeloma arises from clonal expansion of post-germinal centre plasma cells within the bone marrow. The pathogenesis involves a multi-step process:
- Monoclonal gammopathy of undetermined significance (MGUS): Present in ~3.5% of adults >50 years; progresses to myeloma at ~1% per year.
- Smouldering multiple myeloma (SMM): Intermediate asymptomatic stage; 10% risk of progression in the first 5 years, declining thereafter.
- Symptomatic multiple myeloma: Characterised by end-organ damage defined by CRAB criteria or specific biomarkers of malignancy.
Key genetic events include primary translocations involving the immunoglobulin heavy chain locus (t(11;14), t(4;14), t(14;16)), hyperdiploidy, and secondary mutations in NRAS, KRAS, TP53, and DIS3. The bone marrow microenvironment — including osteoclasts, osteoblasts, and stromal cells — plays a critical role in disease progression, bone destruction, and drug resistance.
CRAB Criteria — Defining End-Organ Damage
Investigations (SPEP, Biopsy & Imaging)
Laboratory Investigations
Imaging
Additional Investigations at Diagnosis
- LDH: Elevated LDH indicates aggressive disease biology and extramedullary involvement; required for R-ISS staging.
- Serum viscosity: If symptomatic hyperviscosity (IgA and IgG3 subtypes most likely); treat with plasmapheresis if symptomatic.
- Baseline ECG and cardiac assessment: Prior to carfilzomib or anthracycline-containing regimens.
- Hepatitis B serology: Mandatory before immunosuppressive therapy; antiviral prophylaxis if HBsAg positive or HBcAb positive.
- Immunoglobulin levels: Quantitative IgG, IgA, IgM; monitor for secondary hypogammaglobulinaemia and infection risk.
Staging (ISS) & Prognosis
International Staging System (ISS)
| Stage | Criteria | Median Survival |
|---|---|---|
| I | β₂-microglobulin <3.5 mg/L and albumin ≥35 g/L | 62 months |
| II | Neither stage I nor III | 44 months |
| III | β₂-microglobulin ≥5.5 mg/L | 29 months |
Revised International Staging System (R-ISS)
The R-ISS incorporates cytogenetic risk and LDH into the ISS, providing more refined prognostication:
| R-ISS Stage | Criteria | 5-Year OS |
|---|---|---|
| I | ISS I + standard-risk cytogenetics + normal LDH | ~82% |
| II | Neither I nor III | ~62% |
| III | ISS III + high-risk cytogenetics [t(4;14), t(14;16), del(17p)] or elevated LDH | ~40% |
Cytogenetic Risk Stratification
Management (Bortezomib, IMiDs & ASCT)
Treatment Paradigm Overview
Myeloma management is stratified by transplant eligibility (typically age <70–75, adequate organ function, ECOG 0–2) and risk status. All patients require assessment at a multidisciplinary myeloma clinic with access to autologous stem cell transplantation.
Induction Therapy — Transplant-Eligible Patients
The current Australian standard of care induction is bortezomib, lenalidomide, and dexamethasone (VRd) for 4–6 cycles:
Autologous Stem Cell Transplantation (ASCT)
ASCT remains the standard of care for transplant-eligible patients in Australia. It is performed following 4–6 cycles of induction therapy and PBSC mobilisation with cyclophosphamide + G-CSF or G-CSF ± plerixafor.
Induction Therapy — Transplant-Ineligible Patients
For patients not eligible for ASCT (typically >75 years, significant comorbidities), the following regimens are recommended:
- Daratumumab–bortezomib–melphalan–prednisolone (D-VMP): Daratumumab 16 mg/kg IV weekly × 6 weeks (cycle 1), then every 3 weeks × 8 cycles, then every 4 weeks maintenance. Bortezomib 1.3 mg/m² SC weekly × 9 cycles. Melphalan 9 mg/m² PO days 1–4. Prednisolone 60 mg/m² PO days 1–4. PBS Authority Required for daratumumab.
- Daratumumab–lenalidomide–dexamethasone (DRd): Daratumumab + lenalidomide 25 mg days 1–21 + dexamethasone 40 mg weekly. Increasingly preferred due to superior progression-free survival (MAIA trial).
- Bortezomib–lenalidomide–dexamethasone (VRd-lite): Modified dosing for elderly: bortezomib 1.3 mg/m² SC weekly, lenalidomide 15 mg days 1–21, dexamethasone 20 mg weekly.
Relapsed/Refractory Myeloma
Treatment at relapse depends on the number of prior lines, agents used, duration of prior response, and transplant eligibility. Key regimens include:
Supportive Care — Mandatory for All Patients
- Bisphosphonates: Zoledronic acid 4 mg IV every 4 weeks (or monthly for up to 2 years, then 3-monthly per MRC Myeloma IX data). Adjust for renal function (CrCl <30 mL/min: avoid or halve dose). Pamidronate 90 mg IV is an alternative. PBS General Benefit.
- Denosumab: 120 mg SC every 4 weeks. Alternative to bisphosphonates when renal impairment precludes zoledronic acid. Monitor for hypocalcaemia. PBS Authority Required for myeloma bone disease.
- Infection prophylaxis: Valaciclovir 500 mg PO daily for herpes zoster prophylaxis during bortezomib therapy; consider co-trimoxazole 480 mg PO daily for PCP prophylaxis with significant immunosuppression; IVIg if recurrent bacterial infections and IgG <4 g/L.
- Erythropoiesis-stimulating agents (ESAs): If Hb <100 g/L and on active therapy; combine with iron supplementation if iron-deficient. PBS Authority Required.
- Skeletal protection: Weight-bearing exercise, calcium and vitamin D supplementation, physiotherapy, vertebroplasty for vertebral compression fractures.
- Vaccination: Annual influenza, pneumococcal (Prevenar 13 then Pneumovax 23), COVID-19 boosters; avoid live vaccines. COVID-19 vaccination timing relative to daratumumab should be coordinated with treating team.
- Pain management: Multimodal analgesia; radiotherapy for localised bone pain; surgical stabilisation for impending or actual pathological fractures.
Monitoring & Response Assessment
| Timepoint | Assessment | Details |
|---|---|---|
| Each cycle | SPEP, sFLC, FBC, renal function, calcium | Monitor response and toxicity; adjust doses per protocol |
| Post-induction (cycle 4–6) | SPEP, sFLC, urine IFE, bone marrow biopsy (if CR suspected) | IMWG response criteria: sCR, CR, VGPR, PR, SD, PD |
| Post-ASCT (Day +100) | SPEP, sFLC, bone marrow biopsy, PET-CT (optional) | Assess depth of response; decide on consolidation/maintenance |
| During maintenance | SPEP, sFLC, FBC, renal function every 1–3 months | MRD assessment (flow cytometry or NGS) increasingly used in trials |
| Suspected relapse | SPEP, sFLC, PET-CT or MRI, bone marrow biopsy | Biochemical relapse (25% M-protein increase) vs clinical relapse (CRAB); guide retreatment decisions |
Special Populations
Aboriginal and Torres Strait Islander Health Considerations
Multiple myeloma has a higher age-standardised incidence in Aboriginal and Torres Strait Islander Australians compared to non-Indigenous Australians. ATSI patients are more likely to present with advanced disease, higher rates of renal impairment, hypercalcaemia, and anaemia at diagnosis, contributing to poorer outcomes.
📚 References
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- 2. Palumbo A, Avet-Loiseau H, Oliva S, et al. Revised International Staging System for Multiple Myeloma: a report from International Myeloma Working Group. J Clin Oncol. 2015;33(26):2863–2869. doi:10.1200/JCO.2015.61.2267
- 3. Durie BGM, Hoering A, Abidi MH, et al. Bortezomib with lenalidomide and dexamethasone versus lenalidomide and dexamethasone alone in patients with newly diagnosed myeloma without intent for immediate autologous stem-cell transplant (SWOG S0777): a randomised, open-label, phase 3 trial. Lancet. 2017;389(10068):519–527. doi:10.1016/S0140-6736(16)31594-X
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- 9. Dimopoulos MA, Moreau P, Palumbo A, et al. Carfilzomib and dexamethasone versus bortezomib and dexamethasone for patients with relapsed or refractory multiple myeloma (ENDEAVOR): a randomised, phase 3, open-label, multicentre study. Lancet Oncol. 2016;17(1):27–38. doi:10.1016/S1470-2045(15)00464-7
- 10. Richardson PG, Oriol A, Beksac M, et al. Pomalidomide, bortezomib, and dexamethasone for patients with relapsed or refractory multiple myeloma previously treated with lenalidomide (OPTIMISMM): a randomised, open-label, phase 3 trial. Lancet Oncol. 2019;20(6):781–794. doi:10.1016/S1470-2045(19)30152-4
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- 12. National Health and Medical Research Council (NHMRC). National Statement on Ethical Conduct in Human Research. Canberra: NHMRC; 2023 (updated). Relevant to clinical trial participation in myeloma research.
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