Cisplatin
Platinol · Platinum agent
Proximal tubular ATN + magnesium wasting; the archetype.
ATNLYTEPRE
SevereOpen →
Peptide-conjugated alkylator
Melphalan flufenamide (melflufen)
Pepaxto · Melflu
A peptide-conjugated alkylator that floods myeloma cells with melphalan — and its exposure rises as the kidney fails.
ModeratePeptide-conjugated alkylating agent · approved 2021
Relapsed/refractory multiple myeloma (with dexamethasone)
Signature kidney injury
Acute Tubular Necrosis
Direct nephrotoxicity is not a prominent trial signal; the renal relevance is pharmacokinetic and disease-context. A dedicated phase II study (BRIDGE) in myeloma patients with moderate or severe renal impairment characterized melphalan exposure across renal function and supported a reduced 30 mg dose for moderate impairment, with no new safety signals but substantial treatment-emergent toxicity (including deaths in a heavily pretreated population). As a melphalan-delivery system, its renal liabilities mirror the alkylator class (myelosuppression, and the alkylator-associated risk of tubular injury at high exposure).
Source: Pour et al., Clin Lymphoma Myeloma Leuk 2026 (BRIDGE renal-impairment phase II)
Mechanism of kidney injury
Melflufen is a delivery vehicle that liberates melphalan intracellularly. The kidney is principally the elimination/exposure determinant: in renal impairment, altered handling of the released alkylator changes exposure (the BRIDGE study guided a moderate-impairment dose reduction), and accumulation amplifies systemic alkylator toxicity — chiefly profound myelosuppression. By alkylator-class analogy, high melphalan exposure can stress the proximal tubule and, with tumor cytoreduction, contribute to electrolyte disturbances; intrinsic, biopsy-defined melflufen tubular injury is not well characterized. The dominant, mechanism-anchored renal concern is exposure-driven toxicity in reduced GFR requiring dose adjustment.
Clinical presentation
Predominantly hematologic toxicity (thrombocytopenia, neutropenia, anemia). A creatinine rise would most often reflect underlying myeloma kidney disease, volume depletion, or tumor-lysis-related electrolyte shifts rather than a discrete melflufen tubular lesion. Watch for cytopenia-related complications.
Onset
Cytopenias within the first cycles; any renal change is typically subacute and multifactorial.
Reversibility
Variable
Anticancer mechanism
Lipophilic peptide-drug conjugate of melphalan. It diffuses readily into cells and is rapidly cleaved by aminopeptidases (markedly overexpressed in myeloma cells), releasing and trapping high intracellular concentrations of the alkylator melphalan — yielding roughly a 50-fold enrichment of payload versus free melphalan. With dexamethasone for relapsed/refractory multiple myeloma (regulatory status has shifted; included for onconephrology completeness).
Management
Dose-reduce for renal impairment, interrupt/modify for hematologic toxicity, and provide supportive care (transfusion, growth factors). Manage myeloma-related renal disease and electrolytes; nephrology input for unexplained AKI.
Risk factors
- Moderate-to-severe renal impairment (altered melphalan exposure)
- Underlying myeloma cast nephropathy / hypercalcemia
- Heavy prior therapy and low marrow reserve
- Volume depletion
Prevention
- Assess renal function and reduce the dose for moderate impairment per BRIDGE/label guidance
- Monitor blood counts closely
- Treat underlying myeloma renal disease and maintain hydration
- Tumor-lysis precautions in high-burden disease
Note · Profile included for onconephrology completeness; melflufen's U.S. regulatory status has changed since 2021. The renal message is exposure-and-dose (BRIDGE supports a reduced dose in moderate impairment), not a well-defined intrinsic tubular lesion. Distinct from parent melphalan as a peptide-conjugate with its own PK.
Clinical depth
Renal dose adjustment
Reduced dose (30 mg) recommended for moderate renal impairment (eGFR ~30 to <45 mL/min/1.73 m2) based on the BRIDGE PK study; data in severe impairment are limited (a 20 mg dose was studied). Recalculate eGFR before dosing.
Dialyzability & ESKD dosing
Released melphalan is a small molecule with limited published dialyzability data for the conjugate; no established dosing in dialysis-dependent patients. Use with caution and close monitoring in advanced CKD.
Differential diagnosis
A creatinine rise on melflufen is usually myeloma cast nephropathy, hypercalcemia, prerenal volume depletion, or tumor lysis rather than a primary drug lesion; alkylator-class tubular injury is a theoretical high-exposure concern. Free light chains and calcium help separate disease relapse from drug effect.
Monitoring
- Complete blood count before each cycle and at nadir
- eGFR before dosing
- Serum calcium, free light chains (disease activity)
- Tumor-lysis labs in high-burden disease
Key trials & series
- OCEAN / HORIZON melflufen myeloma program (efficacy/safety context)
- BRIDGE (Pour Clin Lymphoma Myeloma Leuk 2026) renal-impairment phase II PK/dosing study
Clinical pearls
- Melflufen is a melphalan delivery system — think alkylator toxicity, dominated by myelosuppression, with renal function setting exposure.
- Reduce the dose in moderate renal impairment (BRIDGE supports 30 mg); severe-impairment data are limited.
- Most renal events trace to the myeloma (cast nephropathy, hypercalcemia) rather than to melflufen itself.
- Distinct from parent melphalan as a peptide-conjugate with its own pharmacokinetics — do not assume identical dosing.
Where it strikes
Nephron segments
Proximal Tubule
Bulk reabsorption + drug uptake (OCT2, OATs)
Injury signatures
Acute Tubular NecrosisElectrolyte Wasting
Beyond the kidney
Class-level context for the major non-renal toxicities of peptide-conjugated alkylators.
Hematologic
Cytopenias, thrombosis, TMA
- Myelosuppression; secondary malignancy risk
Neurologic
Neuropathy, encephalopathy, ICANS, PRES
- Ifosfamide encephalopathy (chloroacetaldehyde)
Cardiac
Cardiomyopathy, QT, ischemia, myocarditis
- High-dose cyclophosphamide cardiotoxicity
Evidence
3 peer-reviewed references. Citation metadata via PubMed / NLM.
LandmarkBRIDGE (OP-107): A Phase 2 Pharmacokinetic Study of Melflufen Plus Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma and Impaired Renal Function.Pour L et al. · Clin Lymphoma Myeloma Leuk 2026 · PMID 42215355Dedicated renal-impairment PK study guiding a reduced 30 mg dose in moderate impairment, with safety in moderate-to-severe impairment.PMIDSpotlight on Melphalan Flufenamide: An Up-and-Coming Therapy for the Treatment of Myeloma.Morabito F et al. · Drug Des Devel Ther 2021 · PMID 34262262Reviews the aminopeptidase-driven mechanism and ~50-fold intracellular melphalan enrichment that defines melflufen's pharmacology.PMIDConventional Chemotherapy Nephrotoxicity.Gupta S et al. · Adv Chronic Kidney Dis 2021 · PMID 35190107Onconephrology reference for alkylator nephrotoxicity and renal dose-modification principles.