Genzyme Inc. said it expects to begin a second Phase III trial ofThyrogen early next year to bolster results of a recently completedstudy, and it will pay for the additional trial with revenues fromlimited marketing of the drug to thyroid cancer patients.
Sales of Thyrogen to patients other than those participating in thenew Phase III trial will be controlled through an FDA-approvedtreatment investigational new drug (IND) protocol. Thyrogen hasbeen available on a compassionate use basis outside the scope ofclinical studies, but the treatment IND may broaden that availability.
The drug, a recombinant thyroid stimulating hormone (TSH), isdesigned to offset hyperthyroidism experienced when patients whosethyroid glands have been removed undergo subsequent tests todetermine if the disease has spread.
The treatment IND was established by the FDA to permit limited useof drugs prior to market approval for patients whose seriousconditions have no alternative treatments.
Kathleen Rinehart, spokeswoman for the Cambridge, Mass.-basedGenzyme, said charges for Thyrogen to patients participating in thetreatment IND will be based on the costs associated with the secondPhase III trial. She said no dollar amount has been set.
"We'll just break even," Rinehart said. "The charges will cover costsof manufacturing, distribution and research and developmentassociated with the confirmatory Phase III trial."
Details of the second Phase III study have not been determined, shesaid, nor have the parameters for making the drug available throughthe treatment IND. Genzyme said nearly 170,000 people, most ofthem women, have thyroid cancer in the U.S.
Genzyme's chairman and CEO, Henri Termeer, said in a preparedstatement that the FDA asked for the second Phase III trial because"they felt the results [of the first Phase III trial] were not robustenough to waive the normal requirement for a confirmatory studybefore an new drug application (NDA) is submitted."
Rinehart said Genzyme now expects to file the NDA for Thyrogen in1996.
Thyroid cancer patients usually have their thyroid glands removedand must receive daily synthetic thyroid hormone replacements.Subsequent radioiodine tests for metastases are conducted once ortwice a year and require elevated levels of TSH. Those higher levelsof TSH are achieved by discontinuing thyroid hormone replacementsfor three weeks, which leads to hyperthyroidism and such problemsas fatigue, depression and constipation.
Thyrogen is designed to boost TSH levels while patients continuereceiving thyroid hormone replacements.
In the first Phase III test, Genzyme said the Thyrogen scans "were asgood as or better than conventional radioiodine scans in 86 percent"of the 129 evaluable patients. However in 14 percent of the patients,the conventional scans outperformed those conducted withThyrogen, prompting the FDA to request the additional Phase IIIstudy.
The clinical trials also showed Thyrogen was safe and improvedquality of life in 94 percent of the patients who received it. Genzymesaid the only adverse side effect reported was "temporary, usuallymild, nausea" in 16 percent of the patients.
Genzyme's stock (NASDAQ:GENZ) closed Monday at $31.25, up75 cents. n
-- Charles Craig
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