A new drug to treat advanced colon and rectal cancer was approved by FDA just four days after an agency advisory committee recommended the approval.
Camptosar (irinotecan) is for patients whose colorectal cancer has recurred or progressed despite treatment with standard chemotherapy. Approved June 17, as recommended by FDA's Oncology Drugs Advisory Committee, Camptosar is the second in a promising new class of antitumor drugs called camptothecins to be approved in three weeks. Camptothecins work by inhibiting the enzyme topoisomerase-I.
Primary treatment for colorectal cancer is surgery, with or without added chemotherapy or radiotherapy. However, the cancer recurs in about half the patients. The drug Fluorouracil (5-FU), with or without leucovorin (a compound related to the vitamin folic acid), is first-line chemotherapy for patients with colorectal cancer that has spread. However, by the time the cancer is diagnosed, it has already spread in about half of the patients. Treatment options when the cancer does not respond to first-line therapy are very limited.
In three studies of patients whose metastatic (spread) colorectal cancer recurred or progressed despite chemotherapy, the new drug reduced tumor size in about 13 percent of patients for an average of six months. Side effects included diarrhea (in some cases, prolonged or severe enough to require treatment) and leukopenia, a temporary drop in white blood cells that reduces the body's ability to fight infections.
On the oncology advisory committee's recommendation, FDA granted Camptosar accelerated approval based on clinical improvements such as tumor shrinkage, rather than survival time or quality of life. The committee also gave advice on additional studies to further evaluate the safety and effectiveness of the drug. FDA may withdraw its approval if postmarketing studies do not verify clinical benefits.
Camptosar is manufactured by Pharmacia & Upjohn Inc., Kalamazoo, Mich.
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