Various chemotherapy drugs, including vincristine (Oncovin®) and cyclophosphamide (Cytoxan®) have been used as a second or third-line treatment choice for chronic ITP patients. Each has a slightly different side effect profile. While they have been effective in a small percentage of cases, chemotherapy drugs can be quite toxic and have not been approved by the FDA to treat ITP.
Vincristine, a vinca alkaloid derived from the Madagascar periwinkle, inhibits the division of rapidly growing cells. It is frequently used in conjunction with other drugs or infusions for the treatment of lymphoma.1 Vincristine may be used in emergencies or in combination with other therapies for particularly difficult cases of ITP.6
Cyclophosphamide slows cell growth as well as suppresses the immune system. Most often used to treat lymphoma or other cancers, it alters T-cells2, a type of white blood cell, and may be preferentially considered for those ITP patients who have T-cell abnormalities.3
Rituximab (Rituxan® and MabThera®), a B-cell depletion therapy, is considered by some to be a chemotherapy treatment since it is often used to treat cancer.
The dose and duration of the chemotherapy agents varies with the age and size of the patient, other medications and additional medical conditions.
Vincristine is administered through an IV push. It is important that someone who is experienced with the treatment oversee the process since leakage into the surrounding tissue can cause severe problems or death.4
Cyclophosphomide can be given by tablet or injection.5
Chemotherapy agents can reduce the number of white blood cells and increase the chance of getting an infection. The side effects become more severe with increased or additional doses.
The most frequently reported side effects of vincristine are peripheral neuropathy (reduced sensation in fingers and toes), electrolyte imbalance, constipation and hair loss.1
Cyclophosphomide side effects include chemotherapy-induced nausea and vomiting, stomachache, diarrhea, and infertility. Delayed effects include the risk of developing bladder cancer or other tumors.2,5
- Wikipedia:vincristine http://en.wikipedia.org/wiki/Vincristine
- Wikipedia: cyclophosphamide http://en.wikipedia.org/wiki/Cyclophosphamide
- Sabnani I, Tsang P. “Therapeutic implications of T-cell clonopathy of unknown significance in chronic immune thrombocytopenic purpura.” Platelets. 2009 Mar;20(2):135-9. http://www.ncbi.nlm.nih.gov/pubmed/19235057
- Vincristine package insert http://www.accessdata.fda.gov/drugsatfda_docs/label/2014/071484s042lbl.pdf
- Cyclophosphamide package insert http://www.accessdata.fda.gov/drugsatfda_docs/label/2013/012141s090,012142s112lbl.pdf ,012142s112lbl.pdf
- Provan, D, “International consensus report on the investigation and management of primary immune thrombocytopenia,” Blood. 2010 Jan 14; 115 (2):168-86.http://bloodjournal.hematologylibrary.org/cgi/content/full/115/2/168