Sonrotoclax

The kidney injury is a downstream consequence of on-target pharmacology, not intrinsic nephrotoxicity. By potently inhibiting BCL-2, sonrotoclax drives rapid, synchronous apoptosis of a large malignant B-cell mass; the dying cells spill intracellular potassium, phosphate, and purines. Purines are catabolized to uric acid, and uric acid plus calcium-phosphate then precipitate as intratubular crystals, producing obstructive and inflammatory crystal nephropathy — the classic mechanism of tumor-lysis acute kidney injury (Howard, Nat Rev Dis Primers 2024). Hyperphosphatemia with secondary hypocalcemia and hyperkalemia complete the metabolic storm; volume depletion and any concurrent nephrotoxin amplify tubular urate/phosphate concentration and precipitation. The lesson learned with venetoclax — that potency translates directly into tumor-lysis risk requiring graded exposure — applies with at least equal force to this more potent successor (Tambaro & Wierda, Lancet Haematol 2020). The parent drug itself is cleared largely by hepatic metabolism and biliary/fecal excretion rather than by the kidney (Cai, Cancer Chemother Pharmacol 2025), so renal impairment is not the route of elimination — the kidney is the victim of lysis, not the clearance organ.

AKI appears as part of a tumor-lysis picture rather than an isolated creatinine rise: within hours to a few days of an effective (often ramp-up) dose, uric acid, phosphate, potassium, and LDH climb while calcium falls, sometimes with cramps, tetany, arrhythmia, or seizure. Oliguria and a rising creatinine track the crystal load and any volume depletion. The urine sediment is typically bland or shows urate/phosphate crystals. In the absence of tumor lysis, sonrotoclax is not expected to produce a distinct tubular or glomerular lesion.

Management targets the tumor-lysis syndrome, not the drug's clearance. Give aggressive IV hydration to restore renal perfusion and flush the tubules; treat hyperuricemia with rasburicase for significant or established elevations (allopurinol for lower-risk prophylaxis); manage hyperkalemia and hyperphosphatemia medically; and correct calcium only if symptomatic, since repleting calcium into a hyperphosphatemic milieu risks calcium-phosphate deposition. Provide standard supportive AKI care and avoid additional nephrotoxins. Escalate to renal replacement therapy for refractory hyperkalemia, severe symptomatic hyperphosphatemia/hypocalcemia, volume overload, or oliguric AKI unresponsive to medical measures. Interrupt sonrotoclax and re-ramp per protocol for clinical tumor lysis or significant AKI; the ramp-up schedule exists precisely so that dosing can be paused and resumed at a lower step rather than abandoned.Lesion-level management framework

No validated pharmacokinetic renal dose adjustment is established. Sonrotoclax is cleared predominantly by hepatic metabolism and biliary/fecal excretion rather than renal elimination (Cai, Cancer Chemother Pharmacol 2025), so creatinine clearance is not the primary determinant of exposure, and dedicated data in severe renal impairment or dialysis are limited. The clinically decisive dose lever is instead the mandated stepwise ramp-up, which controls tumor-lysis magnitude; dosing is interrupted, delayed, or re-escalated based on tumor-lysis and organ toxicity rather than on baseline GFR. Pre-existing CKD raises tumor-lysis-AKI risk and warrants intensified prophylaxis and monitoring even though it does not, by itself, mandate a lower milligram dose.

Not meaningfully dialyzable as a therapeutic target: sonrotoclax is a small but highly protein-bound, lipophilic molecule cleared hepatically, so hemodialysis is not a route of drug removal and there is no role for dialysis to reverse an overdose of the parent compound. This is distinct from treating its complications — renal replacement therapy is a legitimate and sometimes necessary tool for the tumor-lysis metabolites (potassium, phosphate, uric acid) and for oliguric AKI; it clears the metabolic consequences, not the drug.

The task is to recognize tumor lysis as the cause and exclude mimics. Tumor-lysis crystal nephropathy is favored by hyperuricemia, hyperphosphatemia, hyperkalemia, high LDH, and a falling calcium within 1–3 days of an effective or escalated dose, usually with a bland sediment and often a low fractional excretion of sodium early. Distinguish it from prerenal AKI due to poor intake or GI losses (which lacks the metabolic signature), from concomitant nephrotoxin or contrast exposure, and from pre-existing CKD. Unlike platinum agents or ifosfamide, sonrotoclax is not a primary proximal-tubular toxin — an isolated Fanconi picture or a slowly rising creatinine without electrolyte chaos points elsewhere.