A 72-year-old man with multiple myeloma on lenalidomide-bortezomib-dexamethasone (RVD) regimen has achieved a very good partial response (VGPR). After 4 cycles, serum protein electrophoresis shows a residual M-spike of 0.3 g/dL. Bone marrow shows 3% plasma cells by flow cytometry but immunofixation is still positive. Which response category does this meet?
- A Complete response (CR)
- B Very good partial response (VGPR) ✓
- C Stringent complete response (sCR)
- D Partial response (PR)
Correct answer: B. Very good partial response (VGPR)
Explanation
IMWG response criteria for myeloma: VGPR requires ≥90% reduction in serum M-component and urine M-protein <100 mg/24h OR serum and urine M-protein detectable only by immunofixation. A residual M-spike of 0.3 g/dL with positive immunofixation indicates VGPR if this represents ≥90% reduction from baseline. Complete response (CR) requires negative immunofixation on serum and urine, while stringent CR adds normal FLC ratio and absence of clonal plasma cells by immunohistochemistry. The residual M-spike and positive immunofixation preclude CR.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.