Erdafitinib (Balversa): Bladder Cancer & FGFR Therapy
Erdafitinib acts like a precision rifle for treating bladder cancer. In many patients, tumors grow due to a genetic glitch in FGFR receptors. Think of these as "antennas" on the cell surface that are stuck in the "receive" mode, constantly signaling the cell to grow and divide.
Erdafitinib (Balversa) cuts off these signals by blocking the broken antennas. Without the growth command, cancer cells stop multiplying and die. It is the first targeted therapy approved for patients with advanced urothelial cancer who have stopped responding to standard platinum-based chemotherapy.
Unique to this drug, the dosage is often "up-titrated" based on blood test results (phosphate levels) to ensure maximum efficacy.
Indications
- Urothelial Carcinoma (Bladder Cancer): Treatment of adults with locally advanced or metastatic bladder cancer.
- Crucial Requirement: Effective only in patients with susceptible FGFR3 or FGFR2 genetic alterations. An FDA-approved companion diagnostic test is mandatory before starting therapy to confirm the mutation.
Dosage and administration
Taken once daily, with a smart dosing strategy.
- Starting Dose: 8 mg (typically two 4 mg tablets) once daily.
- Up-Titration (Days 14–21): Your doctor will check your blood phosphate levels. If levels haven't risen enough (indicating the drug isn't fully active yet) and you tolerate the drug well, the dose is increased to 9 mg.
- Instructions: Swallow whole with water, with or without food.
- Eye Disorders: History of central serous retinopathy (CSR) or retinal pigment epithelial detachment.
- Pregnancy and breastfeeding (severe teratogenic risk).
- Severe hepatic impairment.
Pay close attention to your eyes and nails.
- Eyes (Critical): Blurred vision or floating spots. The drug can cause fluid buildup in the retina. Monthly eye exams are mandatory.
- Hyperphosphatemia (Very Common): High blood phosphate levels. This is actually a marker that the drug is working. You may need a low-phosphate diet.
- Nails & Skin: Nail detachment (onycholysis), dry skin, mouth sores.
- Digestive: Diarrhea, dry mouth, taste changes.