Health stocks slunk back from earlier in the week on clinical and regulatory updates and business development news Thursday.

First,

BioCryst

(BCRX) - Get Report

fell $3.81, or 32%, to $7.97 Thursday after announcing after-close Wednesday that a phase II trial didn't meet its primary endpoint

due to the size of needles used to administer flu treatment peravimir. BioCryst is a component of the Nasdaq biotechnology index, which was down 4.52, or 0.5%, to 843.48.

Meanwhile,

Medicure

(MCU)

said Thursday that it completed enrollment in its MEND-CABG II trial, a phase III study will evaluate safety and efficacy of the company's MC-1 in patients undergoing coronary artery bypass graft (CABG) surgery. Enrollment in the 3,000-patient pivotal trial wrapped up about two months early. Shares rose some 4.5% before ending the day at the flat line.

Also,

AstraZeneca

(AZN) - Get Report

said that results published in the

Journal of Clinical Oncology

on Thursday show vandetanib, an oral anti-cancer drug, in combination with docetaxel, improved progression-free survival in patients with advanced non-small-cell lung cancer.

Based on these data, the company has initiated a phase III trial, currently under way, to evaluate vandetanib and docetaxel in second-line treatment of non-small cell lung cancer. The study is recruiting and aims to enroll approximately 1,400 patients. The primary end points of the study are to assess progression free survival. Response rates and overall survival will be secondary endpoints. Shares were up 23 cents, or 0.5%, to $48.44 Thursday.

On the regulatory end,

Wyeth

TST Recommends

(WYE)

said Thursday that the Committee for Medicinal Products for Human Use (CHMP), which gives recommendations to European regulators, gave a positive opinion for the approval of the company's Torisel as a first-line therapy for patients with advanced renal cell carcinoma (RCC) but a negative opinion on granting marketing authorization to mylotarg for acute myeloid leukemia (AML).

"We believe that Mylotarg is an important drug treatment for acute myeloid leukemia, and we will continue to work with the CHMP to address the committee's concerns and pursue a way forward," said Robert Ruffolo, president of Wyeth Research. Shares were trading down 2% to $44.92.

Specialty pharmaceutical company

Acusphere

(ACUS)

said Wednesday after close that it will postpone plans to announce its new product development program, which was originally scheduled for late in the third quarter, because its focusing on partnership discussions primarily for its lead product candidate Imagify, a cardiovascular drug for the detection of coronary artery disease. Shares were climbed 4.9% to $1.50.

Also

Applera

(ABI)

molecular diagnostic company

Celera

(CRA)

said it signed a definitive agreement to buy privately held Atria Genetics, which has a line of diagnostics to identify potential donors in the bone-marrow matching process, for $33 million in cash. The transaction is expected to close in the second quarter of 2008. Celera edged down 44 cents, or 3.2%, to $13.54. Applera climbed 0.5% to $34.41.

Elsewhere on Thursday,

China Medical Technologies

(CMED)

gave up $2.26, or 5.5%, to $38.72, after Brean Murray Carrat downgraded the company to hold from buy citing concern about slowing growth in the High Intensity Focused Ultrasound (HIFU) business.

"In our recent visit to China, we met with several HIFU distributors, as well as with hospitals that have installed HIFU systems. We believe overall HIFU sales growth is clearly slowing down, more than many investors currently expect," Brean Murray Carrat explained in a report Friday.

The report noted that some doctors felt the equipment was underutilized and the treatment is too much of a financial burden for ordinary patients, and also government healthcare administrators are tightening control over large medical equipment procurement, negatively affecting sales.