Protein Electrophoresis vs. Immunofixation Electrophoresis (IFE)

The Diagnostic Figure

Side-by-Side Comparison

Key Points from Textbooks

• Detects M protein as a narrow "church spire" peak on the densitometer or a dense discrete band on agarose gel
• Allows quantitation of the M protein spike - important for monitoring response to treatment
• Monoclonal free light chains (Bence Jones proteins) are rarely seen on serum electrophoresis but are easily detected on urine electrophoresis (UPEP)
• UPEP requires a 24-hour urine collection

• After separating proteins, monospecific antisera are applied against IgG (G), IgA (A), IgM (M), kappa (K), and lambda (λ) - each in its own lane
• A monoclonal protein produces a discrete, sharp band in the corresponding lane (e.g., both the G lane and λ lane light up = IgG lambda myeloma)
• Normal/polyclonal increases produce no discrete bands (just diffuse smearing)
• Particularly important in:
  • Oligosecretory myeloma
  • Primary (AL) amyloidosis
  • Solitary plasmacytoma
  • After treatment of myeloma/macroglobulinemia - to confirm complete response

"Immunofixation should always be performed in conjunction with electrophoresis when multiple myeloma or related disorders are first suspected so as to detect small, unmeasurable M proteins that may be missed on electrophoresis."

• Goldman-Cecil Medicine

Clinical Workflow

Suspicion of plasma cell disorder
        ↓
  SPEP + UPEP (screen)
   ↙              ↘
Abnormal peak     Normal but high suspicion
        ↓                  ↓
     IFE ←————————————————→ IFE still indicated
        ↓
  Identifies: IgG κ? IgA λ? Free light chain only?
        ↓
  Confirms diagnosis (myeloma, MGUS, amyloidosis, etc.)
        ↓
  Follow-up: SPEP for quantitative monitoring of M-spike

Summary in One Line

• Harrison's Principles of Internal Medicine 22E, Fig. 116-2
• Goldman-Cecil Medicine, Chapter 173: Plasma Cell Disorders

Multiple Myeloma: Treatment

Treatment Algorithm

Step 1: Determine Transplant Eligibility

• Physiologic age (<65-70 years is a rough cut-off)
• Good performance status (ECOG 0-2)
• Absence of significant cardiopulmonary or other comorbidities

A. Transplant-Eligible Patients (~50% of newly diagnosed)

1. Induction Therapy (3-4 months)

• Bortezomib 1.3 mg/m² SC days 1, 8, 15; Lenalidomide 25 mg oral days 1-14; Dexamethasone 20-40 mg

• DVRd (Daratumumab + VRd) - particularly favored in high-risk disease
• DRd (Daratumumab + lenalidomide + dexamethasone)
• VCd/CyBorD (Bortezomib + cyclophosphamide + dexamethasone) - especially if renal failure

2. Stem Cell Collection

• Granulocyte colony-stimulating factor (G-CSF) +/- plerixafor or cyclophosphamide
• Collect within 6 months if patient is on lenalidomide (prolonged use compromises stem cell yield)

3. Autologous Stem Cell Transplant (ASCT)

• Conditioning: Melphalan 200 mg/m² (high-dose) followed by infusion of peripheral blood stem cells
• Mortality very low (<1%)
• Not curative but prolongs event-free and overall survival
• Early vs. Delayed ASCT: In standard-risk patients, delaying transplant until first relapse (with stem cells cryopreserved) is an acceptable alternative

4. Maintenance Therapy (post-ASCT)

• Standard-risk: Lenalidomide monotherapy (prolongs PFS and OS)
• High-risk cytogenetics [del17p, t(4;14), t(14;16)]: Bortezomib + lenalidomide combination maintenance, or daratumumab post-ASCT

B. Transplant-Ineligible Patients (~50%)

C. High-Risk Smoldering Myeloma

• Low/intermediate-risk: Observation every 3-4 months only
• High-risk (≥2 of: M-protein >2 g/dL, FLC ratio >20, BM plasma cells >20%): Lenalidomide 25 mg days 1-21 per 28-day cycle x ~2 years; reduces progression to symptomatic myeloma and overall mortality

Key Drug Classes

Important: Acyclovir prophylaxis is mandatory in all patients receiving bortezomib (herpes zoster reactivation risk). DVT prophylaxis (aspirin or anticoagulant) required with all IMiD-containing regimens.

D. Relapsed/Refractory Myeloma

• Goal: choose a regimen with 2+ agents the patient has not previously received or to which disease is not refractory
• If relapse >6 months after stopping therapy: reintroduction of initial regimen is reasonable
• If delayed ASCT planned: perform ASCT at first relapse
• Second ASCT: considered if first remission lasted >18 months (no maintenance) or >36 months (with maintenance)

• CAR-T therapy: Idecabtagene vicleucel (ide-cel) and Ciltacabtagene autoleucel (cilta-cel) - both target BCMA
• Bispecific antibodies: Teclistamab, elranatamab, talquetamab
• Pomalidomide-based regimens: Effective even in lenalidomide-refractory disease
• Carfilzomib (KRd): Effective in bortezomib-refractory disease
• Venetoclax: Exclusively for t(11;14) myeloma

E. Supportive Care / Complication Management

Response Assessment

• sCR (stringent CR), CR, VGPR (very good partial response), PR (partial response)
• Minimal Residual Disease (MRD) negativity is associated with better survival outcomes, though therapy is not routinely changed based on MRD status alone

"NCCN Guidelines for Multiple Myeloma, Version 1.2025 (PMID 40340857)" - updates include new systemic therapy recommendations for both newly diagnosed and relapsed/refractory MM.

• Harrison's Principles of Internal Medicine 22E (2025), Chapter 116
• Goldman-Cecil Medicine, Chapter 173: Plasma Cell Disorders

VTD (Bortezomib + Thalidomide + Dexamethasone)

Mechanism of Action

Indication

Standard Dosing Schedule (21-day cycles)

• Typically 4-6 cycles are given before proceeding to stem cell transplant
• Bortezomib is preferably given subcutaneously (SC) rather than IV to reduce peripheral neuropathy risk

Clinical Evidence

1. Cavo et al., Lancet 2010 - VTD vs. TD (thalidomide + dexamethasone) before and after double ASCT: VTD achieved significantly higher CR rates
2. Rosinol et al. (PETHEMA/GEM), Blood 2012 - VTD superior to VCD and TD as pre-transplant induction; higher rates of CR + VGPR

VTD vs. VRd - Key Differences

"Other similar three-drug combinations (bortezomib, thalidomide, and dexamethasone or bortezomib, cyclophosphamide, and dexamethasone) also achieve >90% response rate." - Harrison's Principles of Internal Medicine 22E

Key Side Effects

• Antithrombotic (aspirin or low-molecular-weight heparin) - DVT risk from thalidomide
• Acyclovir - herpes zoster reactivation risk from bortezomib
• Thalidomide is teratogenic - strict pregnancy prevention program (STEPS program) required

DVTd Variant

Summary

• Harrison's Principles of Internal Medicine 22E, Chapter 116
• Goldman-Cecil Medicine, Chapter 173 (ref A4: CASSIOPEIA trial)

HDT - High-Dose Therapy in Multiple Myeloma

Why It's Done

The HDT-ASCT Process Step by Step

Induction (VRd / VTD / DVRd x 3-6 cycles)
         ↓
Stem Cell Mobilization
(G-CSF ± plerixafor or cyclophosphamide)
         ↓
Peripheral Blood Stem Cell Harvest
(collect enough for 1-2 transplants)
         ↓
HDT: Melphalan 200 mg/m² IV
(conditioning/myeloablative chemotherapy)
         ↓
ASCT: Infusion of stored stem cells (Day 0)
         ↓
Engraftment (typically Day +10 to +14)
         ↓
Maintenance therapy (lenalidomide ± bortezomib)

Key Facts

"Randomized studies comparing standard-dose therapy to high-dose melphalan therapy with hematopoietic stem cell support have shown that HDT can achieve higher overall response rates, with up to 25-40% additional CRs and prolonged progression-free and overall survival; however, few, if any, patients are cured." - Harrison's Principles of Internal Medicine 22E

Who is Eligible?

Early vs. Delayed HDT-ASCT

• Early: Proceed to ASCT right after induction - preferred because it is convenient, avoids prolonged chemotherapy, and achieves deep early response
• Delayed: Collect and cryopreserve stem cells after induction, continue therapy, perform ASCT at first relapse - acceptable option in standard-risk patients. Randomized trials showed no significant difference in overall survival between the two approaches.

Maintenance After HDT-ASCT

Allogeneic Transplant?

• Harrison's Principles of Internal Medicine 22E, Chapter 116