Genzyme Corp. said a Phase III trial of Thyrogen thyroid stimulanthormone, administered before diagnostic scanning, showed itimproved quality of life in 94 percent of thyroid cancer patients andproduced scans as good or better than conventional methods in 86percent of the patients.In 8 percent of the 129 evaluable patients, the conventionalscanning method, which leads to short-term symptoms ofhypothyroidism, was deemed superior, but not clinically relevant.The conventional, or hormone-withdrawal technique, revealeddisease in 6 percent of patients that the Thyrogen scan missed.Both were done in conjunction with radioiodine whole bodyscanning.Different analysts had different interpretations of the results, whichwere released Wednesday, when Genzyme stock(NASDAQ:GENZ) gained 13 cents. The stock, which had beenrising steadily recently, dropped $4 (11 percent) Thursday, closingat $33.63 per share."We're not quite sure why the stock went up as much as it did, andwe're not sure why it went down [Thursday]," Stephen Push,Genzyme's vice president for corporate communications, toldBioWorld. He said even if the trial data were interpretednegatively, which the company thinks would be in error, therelatively minor $50 million U.S. market for Thyrogen doesn'tjustify the drop.Analysts concerned about results cited the 6 percent of cases inwhich the conventional scan revealed disease, but Thyrogen didnot. Push said, however, that Thyrogen picked up the disease in 2.5percent of patients when it was not revealed by conventionalscanning.Patients with thyroid cancer usually have partial or total removal ofthe thyroid gland. Then they take synthetic hormone daily toreplace those that were produced by the gland. Patients are thenchecked once or twice a year for metastasis, usually by hormonewithdrawal followed by radioiodine, which relies on the ability ofthyroid stimulating hormone (TSH) to absorb and retain iodine.Patients stop their hormone supplement for about three weeksbefore the test to get TSH levels well above normal. That is whenthe various symptoms _ fatigue, depression, constipation, etc. _of hypothyroidism set in. Thyrogen recombinant TSH is analternate way of raising TSH levels before testing.David Stone, a managing director at Cowen & Co., told BioWorld,"It is an erroneous conclusion for observers to say this smalldifference reflects an inherent flaw in the Thyrogen scan ratherthan the variability of the procedure."For most diagnostic tests, 90 percent is about as accurate as itgets," Stone added. "The hormone withdrawal scan is known tohave 15 percent false positive results. The withdrawl scan is thegold standard only insofar as it's the only basis doctors have formaking a decision. We think the product's just fine."While the scanning numbers were open to some interpretation, thequality-of-life figures were definitive, Push said. Investigators usedtwo scales, one involving symptoms of hypothyroidism and theother measuring mood states, to measure quality-of-life issues.Push said statistical significance was proved, to an extremely highlevel, that Thyrogen reduced adverse states when compared tohormone withdrawal in all symptoms and mood states.Thyrogen's side effects, he said, mostly involved mild nausea,which occurred in 17 percent of patients."Our next step is a preliminary meeting with the FDA," Push said."We're moving forward with all the aspects of preparing a [newdrug] application so if the FDA says go ahead, we'll be ready to doit late this year or early next year." n
-- Jim Shrine
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