Cetuximab & Panitumumab
Erbitux · Vectibix · Anti-EGFR antibody
TRPM6 magnesium wasting.
LYTE
MildOpen →
CYP17 inhibitor
Abiraterone
Zytiga · Abi
CYP17 blockade drives an ACTH-mediated mineralocorticoid excess — hypokalemia, hypertension, edema.
ModerateAndrogen-biosynthesis inhibitor · approved 2011
Metastatic castration-resistant prostate cancerMetastatic castration-sensitive prostate cancer
Signature kidney injury
Electrolyte Wasting
Mineralocorticoid-excess effects are common: in COU-AA-301 fluid retention, hypertension and hypokalemia were all more frequent than with placebo-prednisone. Severe (grade 3–4) hypokalemia, occasionally to 1.7–2.1 mEq/L, is reported even with concomitant prednisone. Meta-analysis confirms an increased relative risk of hypertension.
Source: de Bono et al., N Engl J Med 2011 (COU-AA-301)
Mechanism of kidney injury
CYP17 inhibition reduces cortisol synthesis, triggering a compensatory rise in pituitary ACTH that drives accumulation of upstream steroid precursors with intact mineralocorticoid activity — chiefly 11-deoxycorticosterone and corticosterone. These agonize the mineralocorticoid receptor in the aldosterone-sensitive distal nephron (principal cells of the late distal tubule/collecting duct), upregulating ENaC and the Na-K-ATPase: sodium and water are retained while potassium and hydrogen are wasted. The result is hypokalemia, metabolic alkalosis, volume expansion and hypertension. Co-administered prednisone suppresses ACTH and largely prevents this; missed glucocorticoid coverage unmasks it. Intrinsic tubular toxicity is not a feature.
Clinical presentation
Hypokalemia (sometimes severe — weakness, ileus, lethargy, arrhythmia or seizure), hypertension, peripheral edema and a hypokalemic metabolic alkalosis with low urinary potassium-sparing only if MR antagonism is added. Renin and aldosterone are suppressed (an apparent-mineralocorticoid-excess biochemical picture). True AKI is uncommon.
Onset
Within the first weeks of therapy; recurs if glucocorticoid coverage is inadequate or interrupted.
Reversibility
Reversible
Anticancer mechanism
Inhibits CYP17A1 (17α-hydroxylase/C17,20-lyase), the rate-limiting enzyme of androgen biosynthesis, blocking testosterone production in testes, adrenals and tumor. Given with prednisone for metastatic castration-resistant and high-risk castration-sensitive prostate cancer.
Management
Replete potassium and treat hypertension; optimize/intensify glucocorticoid dosing to suppress ACTH drive. For refractory mineralocorticoid excess add a mineralocorticoid-receptor antagonist — eplerenone is preferred (a real-world cohort showed it controls toxicity and can even allow steroid-sparing), or amiloride to block ENaC. Spironolactone is avoided in prostate cancer because of partial androgen-receptor agonism.
Risk factors
- Inadequate or missed glucocorticoid co-therapy
- Baseline hypertension or hypokalemia
- Concurrent loop/thiazide diuretics
- Pre-existing adrenal suppression
Prevention
- Co-administer prednisone/prednisolone exactly as labeled
- Monitor potassium, blood pressure and fluid status at least monthly early on
- Pre-emptive potassium repletion
- Use eplerenone (not spironolactone) for residual mineralocorticoid activity
Note · The signature is an electrolyte/blood-pressure syndrome from secondary mineralocorticoid excess, not a primary tubular toxin. Eplerenone or amiloride target the distal nephron directly; spironolactone is generally avoided because it can stimulate the androgen receptor.
Clinical depth
Renal dose adjustment
No formal renal dose adjustment for mild–moderate impairment (not studied in severe CKD/ESKD). Hepatic impairment requires dose reduction. The actionable adjustment is glucocorticoid coverage and potassium/BP management, not renal dosing.
Dialyzability & ESKD dosing
Highly protein-bound (>99%) and hepatically metabolized (CYP3A4/SULT2A1); not meaningfully dialyzable. No specific ESKD dosing established — manage electrolytes clinically.
Differential diagnosis
Differentiate ACTH-driven secondary mineralocorticoid excess (low renin, low aldosterone, hypokalemic alkalosis, responds to eplerenone/steroid) from primary hyperaldosteronism (high aldosterone), diuretic effect, and GI potassium loss; true AKI should prompt a search for a separate cause.
Monitoring
- Serum potassium every cycle (more often if abnormal)
- Blood pressure at each visit
- Fluid/edema status
- Liver function tests per label
- Adherence to prednisone
Key trials & series
- COU-AA-301 (de Bono NEJM 2011) and COU-AA-302 mCRPC trials
- LATITUDE / STAMPEDE castration-sensitive trials
- Gill Clin Genitourin Cancer 2017 eplerenone real-world cohort
Clinical pearls
- The syndrome is apparent mineralocorticoid excess: low renin AND low aldosterone with hypokalemic alkalosis — the culprit is deoxycorticosterone, not aldosterone.
- Use eplerenone, NOT spironolactone — spironolactone's androgen-receptor agonism can blunt the anticancer effect.
- Most hypokalemia is preventable by ensuring the patient actually takes the co-prescribed prednisone.
- Eplerenone can permit steroid-sparing in selected patients who must avoid prednisone (Gill 2017).
Where it strikes
Nephron segments
Distal Tubule / Collecting Duct
Fine-tuning of Na, K, Mg, acid & water
Injury signatures
Electrolyte WastingHypertension
Beyond the kidney
Class-level context for the major non-renal toxicities of cyp17 inhibitors.
Cardiac
Cardiomyopathy, QT, ischemia, myocarditis
- QT, hypertension, fluid retention
Musculoskeletal
Myalgia, myositis, rhabdomyolysis, ONJ
- Bone loss, fatigue, hot flashes
Hepatic / Liver
Transaminitis, hepatitis, VOD/SOS
- Transaminitis (abiraterone)
Evidence
6 peer-reviewed references. Citation metadata via PubMed / NLM.
LandmarkAbiraterone and increased survival in metastatic prostate cancer.de Bono JS et al. · N Engl J Med 2011 · PMID 21612468Pivotal COU-AA-301 trial: mineralocorticoid-related events (fluid retention, hypertension, hypokalemia) more frequent than placebo.PMIDEfficacy of Eplerenone in the Management of Mineralocorticoid Excess in Men With Metastatic Castration-resistant Prostate Cancer Treated With Abiraterone Without Prednisone.Gill D et al. · Clin Genitourin Cancer 2017 · PMID 28131750Real-world cohort showing eplerenone controls abiraterone mineralocorticoid toxicity and can allow steroid avoidance — directly informs management.PMIDAbiraterone-Associated Mineralocorticoid Excess: A Case Report.Shaffi SK et al. · Cureus 2024 · PMID 38318572Nephrology case detailing ACTH-mediated mineralocorticoid excess pathophysiology and management (amiloride).PMIDSerious Hypokalemia Associated with Abiraterone Acetate in Patients with Castration-Resistant Prostate Cancer.Yamamoto Y et al. · Case Rep Urol 2018 · PMID 30305978Two cases of grade 4 hypokalemia (K 1.7–2.1 mEq/L) despite abiraterone plus prednisone.PMIDThe Cardiovascular Toxicity of Abiraterone and Enzalutamide in Prostate Cancer.Iacovelli R et al. · Clin Genitourin Cancer 2017 · PMID 29339044Meta-analysis quantifying increased hypertension risk with abiraterone.PMIDCardiovascular Events and Androgen Receptor Signaling Inhibitors in Advanced Prostate Cancer: A Systematic Review and Meta-Analysis.El-Taji O et al. · JAMA Oncol 2024 · PMID 38842801Large meta-analysis confirming the hypertension/cardiovascular signal of ARSIs including abiraterone.