RUBEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RUBEX (RUBEX).
RUBEX is a monoclonal antibody that inhibits the programmed death-ligand 1 (PD-L1) pathway by binding to PD-L1 on tumor cells and immune cells, thereby blocking its interaction with PD-1 and CD80 (B7.1) receptors. This restores antitumor T-cell immune responses.
| Metabolism | RUBEX is a monoclonal antibody, expected to be degraded into small peptides and amino acids via general protein catabolism; not metabolized by cytochrome P450 enzymes. |
| Excretion | RUBEX is primarily eliminated via biliary excretion (70-80%) as unchanged drug and metabolites, with renal excretion accounting for 15-20% (mostly as metabolites). Less than 5% is excreted fecally. |
| Half-life | Terminal elimination half-life is 18-24 hours in healthy adults, allowing once-daily dosing. In patients with hepatic impairment, half-life may be prolonged. |
| Protein binding | Approximately 85-90% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution is 0.8-1.2 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is 75-85% due to first-pass metabolism. |
| Onset of Action | Oral: 2-4 hours; Intravenous: 15-30 minutes. |
| Duration of Action | Duration of action is 24-36 hours, supporting once-daily dosing. Clinical effect persists beyond the half-life due to active metabolite activity. |
| Molecular Weight | 358.33 |
10 mg/m2 intravenously over 3-5 minutes on days 1 and 8 of a 28-day cycle.
| Dosage form | INJECTABLE |
| Renal impairment | No specific adjustment recommended; caution in severe renal impairment (CrCl <30 mL/min) due to limited data. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: not recommended. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been determined. |
| Geriatric use | No specific adjustment; monitor for increased myelosuppression due to age-related decline in organ function. |
| 1st trimester | Use is contraindicated due to teratogenicity; avoid in pregnancy. |
| 2nd trimester | Use is contraindicated; risk of fetal harm. |
| 3rd trimester | Use is contraindicated; risk of fetal harm and premature labor. |
Clinical note
Comprehensive clinical and safety monograph for RUBEX (RUBEX).
| Placental transfer | RUBEX crosses the placenta; detected in fetal circulation. Degree of transfer is significant with fetal concentrations approximately 50% of maternal levels. |
| Breastfeeding | RUBEX is excreted in breast milk; potential for serious adverse reactions in nursing infants. Discontinue breastfeeding or discontinue drug, taking into account importance of drug to mother. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
PregnancyBreastfeedingHypersensitivity to RUBEX or any component
| Precautions | Immune-mediated pneumonitis, Immune-mediated colitis, Immune-mediated hepatitis, Immune-mediated endocrinopathies (e.g., hypothyroidism, adrenal insufficiency), Immune-mediated nephritis and renal dysfunction, Infusion-related reactions, Embryo-fetal toxicity |
| Food/Dietary | Avoid grapefruit and grapefruit juice during therapy as it may increase doxorubicin levels. No other specific food restrictions. |
| Clinical Pearls |
Loading safety data…
| L5 (Contraindicated) |
| Teratogenic Risk | RUBEX is contraindicated in pregnancy. First trimester: High risk of major congenital malformations including neural tube defects, cardiovascular anomalies, and craniofacial defects. Second and third trimesters: Risk of spontaneous abortion, fetal growth restriction, and neonatal toxicity. Pregnancy must be excluded before initiation. |
| Fetal Monitoring | Monitor complete blood count with differential, liver function tests, renal function, and uric acid levels at baseline and regularly during therapy. Monthly pregnancy tests in women of childbearing potential. Fetal ultrasound if inadvertent exposure occurs. |
| Fertility Effects | RUBEX causes gonadal suppression, amenorrhea, and oligospermia. May impair fertility in both males and females. Effects may be reversible upon discontinuation, but prolonged therapy may lead to permanent infertility. |
| Rubex (doxorubicin) is an anthracycline antineoplastic with cumulative dose-dependent cardiotoxicity. Monitor LVEF before and during therapy; discontinue if signs of CHF develop. Extravasation causes severe tissue necrosis—administer via central line. Observe for red urine (harmless discoloration). |
| Patient Advice | Urine may appear reddish for 1-2 days after treatment; this is normal and not blood. · Report chest pain, shortness of breath, or swelling of ankles immediately. · Avoid sun exposure; use sunscreen as photosensitivity may occur. · Notify your doctor of any signs of infection (fever, sore throat) or unusual bleeding. · Do not receive live vaccines during treatment. |