News from Genzyme Website-Genzyme General Announces Results from Phase 4 Study

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Genzyme General Announces Results from Phase 4 Study of Thyrogen

Date: June 21, 2001

Data Suggest Expanded Role in Thyroid Cancer Screening

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Genzyme General (Nasdaq:GENZ) on June 21 presented interim results

from an ongoing post-marketing study that adds new evidence that

Thyrogen® (thyrotropin alfa injection) can help doctors identify

those at risk of a recurrence of thyroid cancer. The data, which

included a more broad patient population than previous studies, were

presented at The Endocrine Society's 83rd annual meeting in Denver.

Thyrogen was approved by the FDA in late-1998 as an adjunct to two

common thyroid cancer screening tools, serum thyroglobulin (Tg)

testing and whole body scanning. It increases the sensitivity of the

Tg test while also allowing patients to avoid the side effects of

hypothyroidism, such as fatigue, depression and weight gain,

associated with whole body scanning.

The preliminary results presented today suggest that Thyrogen can be

a useful tool in screening patients who have been treated for thyroid

cancer but are in the early stages of disease follow-up, when the

risk of recurrence is highest. The study involved 342 patients at 58

centers in the United States who have had their thyroid gland removed

in the past 10 years after being diagnosed with cancer, and who are

treated with thyroid hormone therapy.

Patients underwent thyroglobulin (Tg) screening both before and after

being administered Thyrogen. After Thyrogen was administered, 18

percent of patients had a rise of at least 2 ng/ml above their

baseline Tg level, an endpoint chosen because it is considered to be

clinically meaningful. Using Thyrogen to accurately identify those

with an elevated Tg level, which is an indicator of residual or

cancerous thyroid tissue, gives physicians a powerful tool for making

decisions about follow-up care.

" This study and previous studies demonstrate that Thyrogen can help

improve the sensitivity of thyroglobulin testing at all ends of the

spectrum, including high-risk patients and those with otherwise

undetectable levels of thyroglobulin, " said the study's principal

investigator, Dr. Leonard Wartofsky of Washington Hospital Center in

Washington, D.C. " This should provide patients and their physicians

with a better understanding of who is at risk for recurrence and may

need increased follow-up care. "

Patients who have had their thyroid gland removed must take thyroid

hormone supplements to maintain their metabolism. Prior to the

introduction of Thyrogen in 1998, these patients had to withdraw from

hormone supplements for up to six weeks when they underwent

diagnostic testing, in order to heighten the sensitivity of the test.

This hiatus causes a patient to experience the symptoms of

hypothyroidism, which include fatigue, weight gain, constipation,

mental dullness, lethargy, depression and other adverse reactions.

Thyrogen, which is a recombinant form of thyroid stimulating hormone,

allows patients to avoid withdrawing from hormone therapy while

undergoing diagnostic testing.

Serum thyroglobulin testing and radioiodine imaging are the two

diagnostic procedures most commonly used with patients being examined

for remnant thyroid tissue, thyroid cancer recurrence or metastases.

In the U.S., physicians order more than 150,000 thyroglobulin tests

and 30,000 radioiodine imaging whole body scans each year for thyroid

cancer patients.

Genzyme General develops and markets therapeutic products and

diagnostic products and services. Genzyme General has four

therapeutic products on the market and a strong pipeline of products

in development focused on the treatment of genetic disorders and

other chronic debilitating diseases with well-defined patient

populations. Genzyme General is a division of the biotechnology

company Genzyme Corporation.

This press release contains forward-looking statements based on

management's current expectations, including without limitation

statements about: the potential expanded utility of Thyrogen; and

Genzyme's estimates of the number of thyroglobulin tests and

radioiodine imaging whole body scans ordered annually in the U.S. for

thyroid cancer patients. Actual results may materially differ due to

numerous factors, including: market acceptance of the use of Thyrogen

for a broader patient population; the accuracy of Genzyme's

information about the number of the above-mentioned tests and scans

ordered annually in the U.S.; and the risks and uncertainties

described in reports filed by Genzyme Corporation with the Securities

and Exchange Commission under the Securities Exchange Act of 1934, as

amended, including without limitation Exhibit 99.2 to Genzyme's 2000

Annual Report on Form 10-K. Genzyme General Division Common Stock is

a series of common stock of Genzyme Corporation. Therefore, holders

of Genzyme General Division Common Stock are subject to all of the

risks and uncertainties described in the aforementioned reports.

Genzyme® and Thyrogen® are registered trademarks of Genzyme

Corporation. All rights are reserved.