Prostate cancer is the second most common type of cancer diagnosed in American men and it is the cause of death for about 27,540 people every year in the US. The malignant disease occurs when there is an uncontrollable growth of cells in the prostate and affects both the reproductive and urinary systems. The prostate is a male gland found below the bladder, near the rectum and around the urethra. Patients often experience symptoms such as urinary problems like a slow or weak urinary stream or the need to urinate more often especially at night, blood in the urine, erectile dysfunction, pain, and weakness or numbness in the limbs.
There are different treatment options to treat prostate cancer, such as watchful waiting or active surveillance, surgery, radiation therapy, cryotherapy, hormone therapy, chemotherapy, vaccine treatment, and bone-directed treatment. Each case is different and the choice of a treatment depend on numerous factors like the patient’s age and expected lifespan, other severe diseases, cancer stage and grade, patients’ and physicians’ feeling and opinions regarding treatment and potential side effects, as well as the probability of curing the cancer.
How Vinblastine Works
Vinblastine is the abbreviation of sulfate salt of vinblastine, a natural alkaloid isolated from the plant Catharanthus roseus (Madagascar periwinkle) with antineoplastic properties. The compound is included in the vinca alkaloids class of medicine, which can also be called plant alkaloids or microtubule inhibitors, and it is used to slow or stop the growth of cancer cells. The mechanism of action of vinblastine is based on the disruption of the microtubule formation and function during mitosis, which interferes with glutamic acid metabolism.
This process results in the drug stopping the cancer cells from separating into two new cells, blocking the growth of the cancer. Vinblastine is available as a clear fluid or as a powder and it is injected intravenously into the patient’s bloodstream. It may be done through a thin and short tube called cannula placed in the arm or through a central line, a portacath, or a PICC line placed directly into a large vein in the chest. The treatment is given by a doctor or nurse at a medical facility, usually once a week. The length of the treatment depends on additional drugs prescribed, how well the body responds to the therapy and on the type of cancer.
Vinblastine to Treat Prostate Cancer
The US Food and Drug Administration (FDA) first approved vinblastine in 1961 for the treatment of leukemia and lymphoma. It is currently commercialized under the brand names Velban and Velsar and it is now used in patients who suffer from breast cancer resistant to other treatments, a type of gestational trophoblastic disease called choriocarcinoma resistant to other chemotherapy drugs, Hodgkin lymphoma, Kaposi sarcoma, mycosis fungoides, Non-Hodgkin lymphoma (NHL), testicular cancer, and prostate cancer. Vinblastine is most commonly administered in combination with estramustine or with estramustine and mitomycin-C. It has been shown effective in reducing PSA levels as well as decrease pain, as explained the authors of the study “Chemotherapeutic Approaches in Advanced Prostate Cancer.”
“Several groups have evaluated the clinical potential of combination chemotherapy with vinblastine (Velban) and estramustine (Emcyt) (VE), two microtubule inhibitors with independent mechanisms of action that appear to provide additive therapeutic effects. Preliminary data obtained from 29 patients with hormone refractory prostate cancer indicated that oral estramustine (140 mg) taken three times daily and weekly intravenous bolus vinblastine (6 mg/m²) provided a clinical response rate of 24% to 50% (as measured by more than 50% reductions in PAP or PSA, respectively) . The overall objective response rate was 30%. Later studies employing different VE dosing (ie, 4 mg/m² weekly vinblastine, 10 mg/kg or 600 mg/m² estramustine) found 54% to 61% rates of PSA reduction. The median duration of response was seven months.”
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