10.3 Genitourinary Malignancies: Prostate, Renal Cell, and Urothelial Carcinomas

10.3 Genitourinary Malignancies: Prostate, Renal Cell, and Urothelial Carcinomas

Genitourinary (GU) malignancies encompass a diverse group of solid tumors originating from the prostate, kidneys, and urothelial tract. Over the last decade, GU oncology has undergone a monumental paradigm shift driven by hormonal intensification, immunotherapeutic checkpoint inhibition, antibody-drug conjugates (ADCs), hypoxia-inducible factor (HIF) targeting, and precision radioligand therapeutics.

Board-certified oncology pharmacists play an essential role in navigating androgen deprivation therapy (ADT) and Androgen Receptor Pathway Inhibitor (ARPI) toxicities (e.g., secondary hyperaldosteronism with abiraterone, metabolic/bone mineral density decline), balancing dual immunotherapy vs. IO-TKI combinations in renal cell carcinoma, managing unique ADC adverse effects (e.g., life-threatening cutaneous reactions and hyperglycemia with enfortumab vedotin), and monitoring radiopharmaceutical logistics.

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1. Prostate Cancer: Disease Continuum and Androgen Deprivation

Prostate cancer progresses through defined clinical states along the androgen axis: Localized -> Biochemical Recurrence -> Non-Metastatic Castration-Resistant (nmCRPC) -> Metastatic Castration-Sensitive (mCSPC) -> Metastatic Castration-Resistant Prostate Cancer (mCRPC).

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|                  PROSTATE CANCER CLINICAL CONTINUUM                         |
|                                                                             |
|   LOCALIZED PROSTATE CANCER:                                                |
|   - Very Low / Low Risk: Active Surveillance                                |
|   - Intermediate / High Risk: Radical Prostatectomy OR Definitive RT + ADT |
|                                                                             |
|   METASTATIC CASTRATION-SENSITIVE PROSTATE CANCER (mCSPC):                  |
|   - Standard: ADT Backbone + INTENSIFICATION (Doublet or Triplet)            |
|   - Avoid ADT monotherapy alone (obsolete standard)                         |
|                                                                             |
|   NON-METASTATIC CASTRATION-RESISTANT (nmCRPC):                             |
|   - Castrate serum testosterone (<50 ng/dL), rising PSA, NO distant mets on |
|     conventional CT/bone scan, PSA Doubling Time (PSADT) <= 10 months       |
|   - Standard: ADT + APALUTAMIDE / ENZALUTAMIDE / DAROLUTAMIDE               |
|                                                                             |
|   METASTATIC CASTRATION-RESISTANT PROSTATE CANCER (mCRPC):                  |
|   - ARPIs (Abiraterone, Enzalutamide) | Taxanes (Docetaxel, Cabazitaxel)    |
|   - PARP Inhibitors (Olaparib, Talazoparib, Rucaparib, Niraparib for HRRm)  |
|   - Radioligand Therapy: Lutetium-177 PSMA-617 (VISION)                     |
|   - Bone-Targeted Alpha Emitter: Radium-223 (ALSYMPCA)                      |
|   - Cellular Immunotherapy: Sipuleucel-T (IMPACT)                           |
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Androgen Deprivation Therapy (ADT) Pharmacology

Castration is defined as achieving and maintaining serum testosterone <50 ng/dL (optimally <20 ng/dL).

• LHRH (GnRH) Agonists (Leuprolide, Goserelin, Triptorelin): Bind pituitary LHRH receptors, causing an initial surge in LH and FSH, producing a transient testosterone flare (Days 1–14). This flare can cause spinal cord compression, urinary obstruction, or bone pain in patients with bulky metastases. Clinical Pearl: Co-administer a first-generation antiandrogen (e.g., Bicalutamide 50 mg PO daily) starting >=7 days prior to or concurrently with the LHRH agonist for 2–4 weeks to block the receptor during the flare.
• LHRH (GnRH) Antagonists (Degarelix SQ monthly, Relugolix 120 mg PO daily): Competitively block pituitary GnRH receptors, inducing immediate LH/FSH and testosterone suppression without testosterone flare. Degarelix and relugolix achieve faster testosterone reduction and carry a lower risk of major adverse cardiovascular events (MACE) compared to LHRH agonists (HERO trial).
• Adverse Effects of Long-Term ADT: Vasomotor hot flashes, loss of libido, sarcopenia, fatigue, metabolic syndrome (insulin resistance, dyslipidemia), osteopenia/osteoporosis (mandates baseline DEXA scan, calcium 1000–1200 mg/day, Vitamin D3 800–2000 IU/day, and bone antiresorptive agents: zoledronic acid or denosumab), and cardiovascular morbidity.

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2. Metastatic Castration-Sensitive Prostate Cancer (mCSPC)

ADT alone is no longer an acceptable standard for mCSPC. Treatment must be intensified with doublet or triplet systemic therapy.

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|                 mCSPC INTENSIFICATION TREATMENT ALGORITHM                   |
|                                                                             |
|                     [CONFIRMED METASTATIC CSPC / HSPC]                      |
|                                     |                                       |
|         +---------------------------+---------------------------+           |
|         |                                                       |           |
|         v                                                       v           |
|  [HIGH-VOLUME / HIGH-RISK DISEASE]               [LOW-VOLUME DISEASE]       |
|  (CHAARTED: >=4 bone mets with >=1               (Oligometastatic /         |
|   beyond axial skeleton, and/or visceral)         Low burden bone mets)     |
|         |                                                       |           |
|         v                                                       v           |
|  [TRIPLET THERAPY (Preferred Category 1)]        [DOUBLET THERAPY]          |
|  1. ADT + DOCETAXEL (6 cycles) +                 1. ADT + ENZALUTAMIDE      |
|     DAROLUTAMIDE (ARASENS Trial:                    (ARCHES / ENZAMET)      |
|     32% reduction in risk of death; HR 0.68)     2. ADT + APALUTAMIDE       |
|  2. ADT + DOCETAXEL (6 cycles) +                    (TITAN Trial)           |
|     ABIRATERONE + PREDNISONE                     3. ADT + ABIRATERONE +     |
|     (PEACE-1 Trial: OS HR 0.75)                     PREDNISONE (LATITUDE)   |
|                                                  4. ADT + Radiation to      |
|  [DOUBLET ALTERNATIVE (Frail / Taxane Infit)]       Primary (STAMPEDE)      |
|  - ADT + Abiraterone / Enzalutamide / Apalutamide                           |
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3. Metastatic Castration-Resistant Prostate Cancer (mCRPC)

In the mCRPC setting, castration therapy with ADT (LHRH agonist/antagonist) must be continued indefinitely to maintain castrate testosterone levels (<50 ng/dL) regardless of subsequent systemic therapy lines.

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|                   mCRPC PRECISION THERAPEUTIC OPTIONS                       |
|                                                                             |
|   1. ANDROGEN RECEPTOR PATHWAY INHIBITORS (ARPIs):                          |
|      - ABIRATERONE ACETATE (1000 mg PO Daily on EMPTY STOMACH) +            |
|        PREDNISONE (5 mg PO BID) [COU-AA-301 / 302 Trials]                   |
|        * CYP17 (17alpha-hydroxylase & C17,20-lyase) inhibitor               |
|        * Toxicities: Secondary Hyperaldosteronism (Hypertension,            |
|          Hypokalemia, Fluid Retention) -> Prevented by co-administered      |
|          prednisone; Hepatotoxicity (monitor AST/ALT/Bilirubin).            |
|      - ENZALUTAMIDE (160 mg PO Daily with or without food) [AFFIRM / PREVAIL]|
|        * AR signaling inhibitor (blocks binding, nuclear translocation, DNA)|
|        * Toxicities: Fatigue (35%), Falls, Seizure risk (0.9%), Drug        |
|          Interactions (Strong CYP3A4, moderate CYP2C9/2C19 inducer).        |
|                                                                             |
|   2. TAXANE CHEMOTHERAPY:                                                   |
|      - DOCETAXEL (75 mg/m2 IV Q3W + Prednisone 5 mg BID) [TAX 327 Trial]    |
|      - CABAZITAXEL (20-25 mg/m2 IV Q3W + Prednisone 5 mg Daily) [TROPIC/CARD|
|        * Overcomes docetaxel resistance (poor substrate for P-gp efflux)    |
|        * High myelosuppression -> Mandatory primary G-CSF prophylaxis.      |
|                                                                             |
|   3. PARP INHIBITORS IN HOMOLOGOUS RECOMBINATION REPAIR (HRR) MUTATIONS:    |
|      - OLAPARIB (300 mg PO BID) [PROfound Trial: BRCA1, BRCA2, ATM, etc.]   |
|      - RUCAPARIB (600 mg PO BID) [TRITON3 Trial: BRCA1/2, ATM]              |
|      - TALAZOPARIB + ENZALUTAMIDE [TALAPRO-2: HRR-mutated mCRPC]            |
|      - NIRAPARIB + ABIRATERONE / PREDNISONE [MAGNITUDE Trial: BRCA1/2-mut]  |
|      * Synthetic lethality in homologous recombination deficiency;          |
|        profound benefit in BRCA2 alterations. Monitor Anemia & Platelets.   |
|                                                                             |
|   4. RADIOPHARMACEUTICALS:                                                  |
|      - LUTETIUM-177 VIPIVOTIDE TETRAXETAN (177Lu-PSMA-617) [VISION Trial]:  |
|        * 7.4 GBq (200 mCi) IV Q6W for up to 6 cycles                        |
|        * Beta-emitting radioligand targeting PSMA on prostate cancer cells  |
|        * Requires PSMA-PET (68Ga-PSMA-11 or 18F-DCFPyL) positivity          |
|        * Toxicities: Myelosuppression (anemia, thrombocytopenia), Xerostomia|
|          (dry mouth in 39%), renal impairment.                              |
|      - RADIUM-223 DICHLORIDE [ALSYMPCA Trial]:                              |
|        * Alpha-emitting calcium mimetic targeting bone osteoblastic turnover|
|        * Indicated for symptomatic bone metastases WITHOUT visceral disease |
|        * DO NOT COMBINE WITH ABIRATERONE (increased bone fractures/death)   |
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4. Renal Cell Carcinoma (RCC): Clear Cell vs. Non-Clear Cell

Clear Cell Renal Cell Carcinoma (ccRCC, ~75–80% of RCC) is driven by loss or inactivation of the Von Hippel-Lindau (VHL) tumor suppressor gene on chromosome 3p. Loss of VHL prevents ubiquitin-mediated degradation of HIF-1alpha and HIF-2alpha, leading to constitutive transcription of VEGF, PDGF, and TGF-alpha, producing hypervascular tumors.

IMDC (Heng) Risk Stratification for Metastatic ccRCC

Systemic therapy selection is guided by the International Metastatic RCC Database Consortium (IMDC) risk model, based on 6 clinical factors:

1. Karnofsky Performance Status (KPS) < 80%
2. Time from initial diagnosis to systemic therapy < 1 year
3. Hemoglobin < Lower Limit of Normal (LLN)
4. Corrected Serum Calcium > Upper Limit of Normal (ULN)
5. Absolute Neutrophil Count > ULN
6. Platelet Count > ULN

• Favorable Risk (0 factors): Median OS ~43–50 months.
• Intermediate Risk (1–2 factors): Median OS ~22–27 months.
• Poor Risk (3–6 factors): Median OS ~8–12 months.

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|                 METASTATIC ccRCC FRONTLINE TREATMENT MATRIX                 |
|                                                                             |
|   [INTERMEDIATE / POOR RISK IMDC (Category 1 Options)]                      |
|   1. DUAL CHECKPOINT BLOCKADE:                                              |
|      * NIVOLUMAB (3 mg/kg) + IPILIMUMAB (1 mg/kg) IV Q3W x 4 doses ->       |
|        Nivolumab maintenance 240 mg Q2W / 480 mg Q4W [CheckMate 214]       |
|      * High Complete Response rate (~10-12%), durable OS plateau            |
|   2. IO + TKI COMBINATIONS:                                                 |
|      * PEMBROLIZUMAB (200 mg Q3W) + AXITINIB (5 mg PO BID) [KEYNOTE-426]   |
|      * NIVOLUMAB (240 mg Q2W) + CABOZANTINIB (40 mg PO Daily) [CheckMate 9ER]|
|      * PEMBROLIZUMAB (200 mg Q3W) + LENVATINIB (20 mg PO Daily) [CLEAR]     |
|        (CLEAR Trial: Highest median PFS 23.9 mo and ORR 71%)                |
|                                                                             |
|   [FAVORABLE RISK IMDC]                                                     |
|   - Preferred: IO + TKI Combination (Pembrolizumab + Axitinib / Lenvatinib; |
|     Nivolumab + Cabozantinib)                                               |
|   - Alternative: Active Surveillance (indolent disease) OR Single-Agent TKI |
|                                                                             |
|   [ADJUVANT ccRCC THERAPY (KEYNOTE-564)]                                    |
|   - High-Risk Resected ccRCC (pT2 high-grade, pT3-T4, pN+, or M1 NED)      |
|   - PEMBROLIZUMAB 200 mg Q3W (or 400 mg Q6W) x 1 YEAR                      |
|   - Landmark Overall Survival Benefit: 38% reduction in death (HR 0.62)     |
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Belzutifan (Welireg): Breakthrough HIF-2alpha Inhibitor

• Mechanism of Action: First-in-class small molecule that selectively binds to the PAS-B domain of HIF-2alpha, blocking its heterodimerization with HIF-1beta (ARNT) and inhibiting downstream oncogenic transcription of VEGF, cyclin D1, and erythropoietin.
• Indications:
  • Advanced clear cell RCC following prior PD-1/PD-L1 checkpoint inhibitor and VEGF-TKI therapy (Phase 3 LITESPARK-005 Trial).
  • Adult patients with Von Hippel-Lindau (VHL) disease who require therapy for associated RCC, central nervous system hemangioblastomas, or pancreatic neuroendocrine tumors.
• Dosing: 120 mg PO once daily continuously with or without food.
• Signature Class Toxicities & Interception:
  • Severe Anemia (Boxed Warning / Class Effect in >80–90%; Grade 3 in ~30%): Because HIF-2alpha regulates physiological renal erythropoietin (EPO) production, belzutifan directly suppresses erythropoiesis. Monitoring: Check baseline and periodic hemoglobin. Manage with Erythropoiesis-Stimulating Agents (ESAs: epoetin alfa, darbepoetin) and blood transfusions. Withhold for Hb <8.0 g/dL.
  • Severe Hypoxia (Class Effect in 10–15%): Monitor oxygen saturation by pulse oximetry at baseline, periodically, and with any exertional dyspnea. Withhold for SpO2 <88% or severe exercise-induced desaturation; administer supplemental oxygen.

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5. Urothelial Carcinoma: The Transformed Paradigm

Urothelial carcinoma comprises malignancies of the urinary bladder (~90%), renal pelvis, ureters, and urethra.

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|                   UROTHELIAL CARCINOMA CLINICAL PATHWAYS                    |
|                                                                             |
|   NON-MUSCLE INVASIVE BLADDER CANCER (NMIBC: Ta, T1, CIS):                  |
|   - Transurethral Resection of Bladder Tumor (TURBT)                        |
|   - Followed by Intravesical BCG (Bacillus Calmette-Guerin)                 |
|     * Induction: 6 weekly instillations                                     |
|     * Maintenance: 3 weekly instillations at 3, 6, 12, 18, 24, 30, 36 months|
|   - BCG-Unresponsive NMIBC: Intravesical Nadofaragene firadenovec,          |
|     Nogapendekin alfa inbakicept (IL-15 superagonist) + BCG, or Pembrolizumab|
|                                                                             |
|   MUSCLE-INVASIVE BLADDER CANCER (MIBC: cT2-T4a N0 M0):                     |
|   - Standard: NEOADJUVANT CISPLATIN CHEMOTHERAPY (ddMVAC x 4c with G-CSF    |
|     OR Gemcitabine + Cisplatin x 4c) -> RADICAL CYSTECTOMY + PELVIC LND     |
|   - Adjuvant Immunotherapy (CheckMate 274 Trial):                           |
|     * High-Risk Resected MIBC (ypT2-ypT4a or ypN+ post-neoadjuvant chemo;   |
|       or pT3-pT4a / pN+ without prior neoadjuvant cisplatin)                |
|     * ADJUVANT NIVOLUMAB 240 mg Q2W / 480 mg Q4W x 1 YEAR (DFS HR 0.70)    |
|                                                                             |
|   METASTATIC UROTHELIAL CARCINOMA (mUC) - THE EV-302 REVOLUTION:            |
|   - UNIVERSAL FRONTLINE STANDARD OF CARE:                                   |
|     * ENFORTUMAB VEDOTIN (1.25 mg/kg D1, 8) + PEMBROLIZUMAB (200 mg D1) Q21D|
|     * EV-302 / KEYNOTE-A39 Trial: Doubled mOS (31.5 vs 16.1 mo; HR 0.47)   |
|       and mPFS (12.5 vs 6.3 mo; HR 0.45) over standard Platinum Doublet!    |
|     * Replaces Gemcitabine + Cisplatin/Carboplatin as Frontline Standard.   |
|                                                                             |
|   - Alternative Frontline Options (EV Unfit / Ineligible):                  |
|     * Gemcitabine + Cisplatin + Nivolumab -> Nivolumab Maint (CheckMate 901)|
|     * Gemcitabine + Cisplatin/Carboplatin x 4-6c -> Consolidation Avelumab  |
|       Maintenance (JAVELIN Bladder 100 Trial: mOS 23.8 vs 15.0 mo, HR 0.69) |
|                                                                             |
|   - Targeted Second-Line Therapeutics:                                      |
|     * ERDAFITINIB (FGFR1-4 TKI) for susceptible FGFR3/2 alterations (THOR)  |
|     * SACITUZUMAB GOVITECAN (Trop-2 directed ADC with SN-38 payload)        |
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Enfortumab Vedotin (EV): Mechanism and Toxicity Mitigation

• Target & Structure: Fully human monoclonal antibody directed against Nectin-4 (cell adhesion molecule highly expressed on >90% of urothelial carcinomas), conjugated via a protease-cleavable valine-citrulline linker to the microtubule-disrupting agent Monomethyl Auristatin E (MMAE).
• Signature Boxed Warnings & Class Toxicities:
  • Severe Cutaneous Adverse Reactions (Boxed Warning): Severe rash, maculopapular eruptions, Stevens-Johnson syndrome (SJS), and Toxic Epidermal Necrolysis (TEN). Monitor closely; withhold for Grade 2 worsening rash; permanently discontinue for suspected SJS/TEN or exfoliative dermatitis.
  • Hyperglycemia & Diabetic Ketoacidosis (Boxed Warning): EV triggers severe, life-threatening hyperglycemia even in patients with normal baseline glucose. Monitor blood glucose closely. Withhold EV if blood glucose >250 mg/dL until controlled.
  • Peripheral Neuropathy (Sensory and Motor in ~50%): Axonal polyneuropathy from MMAE tubulin inhibition. Dose reductions (1.0 mg/kg -> 0.75 mg/kg -> 0.5 mg/kg) or treatment holds required for Grade >=2 neuropathy.
  • Ocular Disorders: Keratitis, dry eye symptoms; prophylactic artificial tears and ophthalmologic evaluation for persistent visual changes.

Erdafitinib (Balversa) in FGFR-Altered Urothelial Carcinoma

• Indication: Adult patients with susceptible FGFR3 genetic alterations (mutations or fusions) whose mUC progressed on prior systemic therapy (THOR Trial: OS HR 0.64 vs chemotherapy).
• Dosing & Dose Titration: Initial dose is 8 mg PO once daily. Assess serum phosphate levels at Day 14 to 21. If serum phosphate is <9.0 mg/dL and there are no drug-related toxicities, escalate dose to 9 mg PO once daily.
• Key Toxicities: Hyperphosphatemia, central serous retinopathy (mandatory baseline/periodic visual field and optical coherence tomography exams), onycholysis, and severe dry mouth / stomatitis.

Master Summary Matrix: Genitourinary Landmark Practice Milestones