Methotrexate (high-dose)
Trexall · Antifolate
Crystal nephropathy; glucarpidase rescue.
XTALATN
ModerateOpen →
BCL-2 inhibitor
Venetoclax
Venclexta · Veneto
A potent apoptosis inducer whose deep, rapid kill can crash the kidneys with tumor lysis — the mandated ramp-up exists for the kidney.
SevereBCL-2 inhibitor · approved 2016
CLL/SLLAcute myeloid leukemia (combinations)
Signature kidney injury
Crystal / Obstructive Nephropathy
Representative incidence3%
Tumor lysis syndrome is the defining renal risk, concentrated during the weekly dose ramp-up. Early-development unmitigated dosing caused fatal TLS; with the mandated 5-week ramp-up and risk-stratified prophylaxis, clinical TLS fell to ~3% (e.g., grade 3/4 laboratory TLS 3.1% in MURANO), and structured protocols can drive it near zero.
Source: Seymour et al., NEJM 2018 (MURANO; 3.1% grade 3/4 lab TLS)
Toxicity fingerprint
Tap a signature to trace where it strikes the nephron.
0%incidence
SeveritySevere
ReversibilityPartially reversible
Evidence0 refs
Nephron map
Vasculature / Endothelium
Proximal Tubule
Distal Tubule / Collecting Duct
Tubular LumenThe urine flow path
Crystal / Obstructive Nephropathy
Intratubular precipitation of drug or metabolite — high-dose methotrexate and tumor lysis crystals.
Mechanism of kidney injury
Rapid, synchronous apoptosis releases intracellular potassium, phosphate, and nucleic acids; nucleic acids are catabolized to uric acid. Uric acid and calcium-phosphate crystallize within distal tubules causing intratubular obstruction and crystal nephropathy, compounded by urate-driven afferent vasoconstriction and ischemic ATN — classic tumor-lysis AKI. The risk is exquisitely dose-step dependent, which is why the escalation schedule and prophylaxis are mandated.
Clinical presentation
Hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia and rising creatinine during ramp-up; oliguric AKI, cardiac arrhythmia and (historically) death in severe cases. Onset clusters within 24–72 h of each dose escalation step.
Onset
Acute — typically within hours to days of each dose-escalation step during the ramp-up.
Reversibility
Partially reversible
Anticancer mechanism
Selective BH3-mimetic inhibitor of the anti-apoptotic protein BCL-2; it displaces pro-apoptotic effectors (BIM/BAX/BAK) to restore mitochondrial apoptosis in malignant cells, producing deep, rapid remissions in CLL/SLL and (with azacitidine/low-dose cytarabine) in AML.
Management
Aggressive IV hydration, rasburicase for hyperuricemia, correct hyperkalemia/hyperphosphatemia/hypocalcemia, and hold venetoclax. Initiate renal replacement therapy early for refractory hyperkalemia, severe hyperphosphatemia/uremia or oliguria — the threshold is lower than usual because cell breakdown is ongoing.
Risk factors
- High tumor burden / bulky lymphadenopathy (≥5 cm) or high absolute lymphocyte count
- High baseline LDH
- Pre-existing CKD (reduced urate/phosphate clearance)
- Volume depletion
- Inadequate ramp-up or prophylaxis
Prevention
- Mandatory weekly dose ramp-up (e.g., 20→50→100→200→400 mg over 5 weeks)
- Risk-stratified TLS prophylaxis: IV/oral hydration plus allopurinol (low/medium risk) or rasburicase (high risk)
- Laboratory monitoring at and after each escalation (pre-dose, 6–8 h, 24 h)
- Inpatient admission with hydration for high-risk patients; consider pre-debulking (e.g., ibrutinib) to lower the TLS-risk category
Note · TLS risk is dose-ramp dependent and largely mitigated by the mandated escalation and prophylaxis schedule — the ramp-up protocol is, in effect, a nephroprotective regimen. Pre-treatment debulking shifts patients to a lower TLS-risk category.
Clinical depth
Renal dose adjustment
No dose adjustment for mild-to-moderate renal impairment; in severe impairment (CrCl <30) and dialysis, data are limited and patients warrant intensified TLS prophylaxis/monitoring because reduced clearance of urate and phosphate magnifies TLS risk rather than because venetoclax itself accumulates renally (it is hepatically cleared).
Dialyzability & ESKD dosing
Not meaningfully dialyzed — highly protein-bound (>99%), hepatically (CYP3A) metabolized small molecule with negligible renal excretion. Dialysis is used to treat TLS metabolic complications, not to remove the drug.
Differential diagnosis
Tumor-lysis AKI (hyperuricemia + hyperphosphatemia + hyperkalemia + hypocalcemia, urate/phosphate crystals) vs prerenal azotemia of hydration deficit vs contrast or other nephrotoxins. The temporal lock to ramp-up steps is the giveaway.
Monitoring
- TLS panel (uric acid, potassium, phosphate, calcium, creatinine) pre-dose, 6–8 h and 24 h after each ramp-up step
- Strict intake/output and volume status during escalation
- Continue intensified monitoring at each new dose level until 400 mg tolerated
Key trials & series
- Roberts et al., NEJM 2015 — pivotal R/R CLL phase 1 (clinical TLS including a death drove the mandated ramp-up)
- Seymour et al., NEJM 2018 — MURANO (venetoclax-rituximab; 3.1% grade 3/4 laboratory TLS)
- Al-Sawaf et al., Lancet Oncol 2020 — CLL14 (fixed-duration venetoclax-obinutuzumab frontline)
Clinical pearls
- The 5-week ramp-up and prophylaxis schedule is fundamentally a kidney-protection protocol — never skip dose escalation or TLS labs.
- TLS risk scales with tumor bulk and baseline renal function; debulking (e.g., with ibrutinib) can downgrade the risk category before venetoclax.
- In venetoclax TLS, start renal replacement therapy at a lower threshold than usual because ongoing apoptosis keeps releasing potassium and phosphate.
Where it strikes
Nephron segments
Tubular Lumen
The urine flow path
Proximal Tubule
Bulk reabsorption + drug uptake (OCT2, OATs)
Vasculature / Endothelium
Glomerular & peritubular capillaries
Injury signatures
Crystal / Obstructive NephropathyAcute Tubular NecrosisPrerenal / Hemodynamic AKIElectrolyte Wasting
Beyond the kidney
Class-level context for the major non-renal toxicities of bcl-2 inhibitors.
Hematologic
Cytopenias, thrombosis, TMA
- Neutropenia
Immune / Infusion
CRS, infusion reactions, irAEs, anaphylaxis
- Tumor-lysis-driven systemic effects
Evidence
7 peer-reviewed references. Citation metadata via PubMed / NLM.
LandmarkTumour lysis syndrome in patients with chronic lymphocytic leukaemia treated with BCL-2 inhibitors: risk factors, prophylaxis, and treatment recommendations.Tambaro FP et al. · Lancet Haematol 2020 · PMID 32004486Authoritative review of venetoclax TLS pathophysiology, risk stratification and prophylaxis.PMIDTargeting BCL2 with Venetoclax in Relapsed Chronic Lymphocytic Leukemia.Roberts AW et al. · N Engl J Med 2015 · PMID 26639348Pivotal R/R CLL trial; clinical TLS (including a fatal case) that drove the mandated dose ramp-up.PMIDVenetoclax-Rituximab in Relapsed or Refractory Chronic Lymphocytic Leukemia.Seymour JF et al. · N Engl J Med 2018 · PMID 29562156MURANO registrational phase 3; reports grade 3/4 laboratory TLS rate (3.1%) under the ramp-up.PMIDExpert consensus guidelines for the prophylaxis and management of tumor lysis syndrome in the United States: Results of a modified Delphi panel.Perissinotti AJ et al. · Cancer Treat Rev 2023 · PMID 37579533Modern TLS guideline addressing venetoclax-class risk and renal/electrolyte management.PMIDGuidelines for the management of pediatric and adult tumor lysis syndrome: an evidence-based review.Coiffier B et al. · J Clin Oncol 2008 · PMID 18509186Foundational TLS risk-stratification/prophylaxis framework (hydration, rasburicase, renal endpoints).PMIDRenal involvement in chronic lymphocytic leukemia.Wanchoo R et al. · Clin Kidney J 2018 · PMID 30288263Onconephrology review highlighting venetoclax-associated tumor lysis as a key nephrotoxicity.PMIDEmergencies in Hematology: Why, When and How I Treat?Duminuco A et al. · J Clin Med 2024 · PMID 39768494Review of tumor lysis syndrome pathophysiology, electrolyte derangements and AKI management.