According to results recently presented at the 2002 annual meeting of the American Society of Hematology, the agent Velcade™ (bortezomib, formerly PS-341) demonstrates anti-cancer activity and improves quality of life in patients with multiple myeloma that has stopped responding to standard therapies.
Multiple myeloma is a cancer involving important immune (infection-fighting) cells called plasma cells. Plasma cells aid the body in fighting infection by producing specialized proteins called antibodies that have the ability to target and/or kill foreign cells. In multiple myeloma, cancerous plasma cells produce abnormal and excessive antibodies that do not have the ability to properly fight infection. In addition, the cancerous plasma cells accumulate in the bone marrow, suppressing the normal formation and function of other cells that are necessary for normal production of blood cells and immune functions. The excessive accumulation of cancer cells in the bone marrow ultimately leads to the formation of tumors in the bone and to the breakdown of bone. Furthermore, the cancerous plasma cells secrete dysfunctional antibodies, referred to as M proteins, which can be measured in the blood. Once multiple myeloma stops responding to standard therapies, it is referred to as “refractory”. Patients with refractory multiple myeloma are currently left with few effective treatment options and long-term survival is suboptimal.
Velcade™ is classified as a proteosome inhibitor and has been granted “fast-track” status with the United States Food and Drug Administration (FDA). It is currently in its last phases of clinical trials prior to the FDA approval process. Proteosomes are proteins existent in virtually every cell that are responsible for the breakdown and re-use of other proteins in a cell. In addition, Velcade™ has demonstrated an effect on several proteins that regulate cellular growth and replication by either inhibiting or facilitating progression of numerous biological pathways.
A recent clinical trial evaluating Velcade™ involved 202 patients with relapsed or refractory multiple myeloma. This group of patients had an average age of approximately 60 years and had received extensive prior therapy, with 74% having previously received thalidomide and 54% having previously received high-dose therapy. The average number of prior therapies received by each patient was 6. Treatment in this trial consisted of Velcade™ and dexamethasone (steroid) if Velcade™ did not demonstrate an anti-cancer response after two courses of treatment.
The overall anti-cancer response rate was 35%. The overall average survival was 16 months and the average time to cancer progression was 7 months. For patients who responded to treatment, quality of life was dramatically improved and blood transfusion requirements were reduced. The most common side effects were nausea, diarrhea and loss of appetite which were generally mild to moderate. The current ongoing clinical trial compares Velcade™ to high-dose dexamethasone in patients with recurrent multiple myeloma.
These researchers concluded that Velcade™ is a promising therapeutic option for patients with refractory multiple myeloma. Future clinical trials will help to determine the optimal timing of the use of Velcade™ in the treatment of multiple myeloma. Patients with refractory multiple myeloma may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating Velcade™ or other promising therapies.
Reference: Richardson P, Barlogie B, Berenson J, et al. A phase II multicenter study of the proteasome inhibitor Bortezomib (Velcade™) formerly PS-341 in multiple myeloma patients (Pts) with relapsed/refractory disease. Proceedings of the 2002 meeting of the American Society of Hematology. Blood.100;104a: abstract number 385.
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