Canadian-based Biomira Inc. plans a Phase III trial of its Theratopecancer drug next year based on Phase II studies demonstrating thetherapeutic vaccine extended mean survival of breast cancer patientsnearly three times as long as those who received standard treatmentssuch as chemotherapy and radiation.
The Edmonton, Alberta company also will meet with the FDA andCanadian regulatory officials to determine if the Phase II data issufficient for submission of a drug approval application forTheratope under accelerated review guidelines for cancer therapies inboth countries.
The Phase II trial involved 50 patients with metastatic or recurrentbreast cancer. All the patients received one of three Theratopeprograms. The participants' responses were compared with a"retrospective control group" composed of breast cancer patientswith similar age and disease profiles and similar treatment historieswith chemotherapy, radiation or other conventional therapies. Thepatients in the control group were culled from information maintainedby the National Oncology Database, in Rockville, Md.
Although not a head-to-head comparison, the only significantdifference between the Theratope-treated groups and the controlgroup was the use of Biomira's therapeutic vaccine.
Median survival of patients in the control group was 9.2 months. TheTheratope group in which 25 patients received a low dose ofintravenous cyclophosphamide followed by the Theratope vaccineexperienced a mean survival of 26.5 months. Findings showedpatients receiving Theratope in this study and previous trialsexperienced minimal toxicity with the vaccine.
Cyclophosphamide, a chemotherapeutic, is used to kick start theimmune system prior to pushing it into high gear with Theratope. Thecyclophosphamide dose used is not cytotoxic.
Theratope uses a synthetic cancer antigen loaded on a protein carrierto stimulate an immune system attack on tumors.
The Theratope treatment program involving intravenousadministration of low dose cyclophosphamide followed by thevaccine will be used in the Phase III trial.
In the Phase II study, the other two groups received either 12 days oforal cyclophosphamide followed by Theratope or Theratope alone.Median survival for all 50 patients in the three Theratope treatmentgroups was 19.1 months, compared with 9.2 months for the controlgroup.
Grant MacLean, Biomira's vice president of clinical and regulatoryaffairs, said the Phase III trial is expected to begin in January 1997and to be complete in two years. However, interim data will beexamined at six months and 18 months, and either analysis could beused to support submission of a drug approval application.
MacLean said use of the retrospective control group in the Phase IIstudy will be one aspect of discussions with regulatory officials onthe possibility of filing for accelerated review in Canada and the U.S.
Theratope May Be Used For Colon Cancer
For treatment of metastatic breast cancer, Theratope is targeted foruse after first-line chemotherapy treatments to keep the cancer inremission and extend survival. The vaccine, MacLean added, may beevaluated as a first-line therapy in subsequent trials for other cancers,such as colon.
In the Phase III breast cancer trial, patients will receive chemotherapyand then will be divided into two groups: one will receive theTheratope vaccine program, which includes the low dosecyclophosphamide, and the other will receive a placebo.
The primary endpoint is median survival, but the study also willevaluate the rate of progression of disease in the placebo andtreatment groups.
Biomira is seeking a corporate partner for Theratope, but willproceed with the Phase III trial without one. In October, Biomiraraised $27 million through a public offering of 4 million shares at$6.75 per share to support continued clinical development ofTheratope.
Biomira's stock (NASDAQ:BIOMF) closed Friday at $6.937, down$0.125. n
-- Charles Craig
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