Biotech stocks overall ticked up slightly Thursday, but one notable exception was

Cell Genesys

( CEGE), which sank 75% to 17 cents on word of a serious clinical setback.

The decline in Cell Genesys came after the company said it terminated a second study on its prostate cancer vaccine

GVAX

, and said it would cut 75% of its workforce.

Still, Cell Genesys did little to hurt the Nasdaq Biotechnology index, of which it's a component. The index added 3.3%, outperforming the broader market.

The Amex Biotechnology index added 2.1%. Components and biotech bellwethers

Amgen

(AMGN) - Get Report

and

Celgene

(CELG) - Get Report

added 1.6% and 1.5%, respectively.

Celgene

(CELG) - Get Report

and Acceleron Pharma said they have initiated a midstage trial on an investigational bone loss therapy in patients with multiple myeloma. It will trigger a $5 million milestone payment from Celgene to Acceleron.

Following the close, earnings are expected from

Gilead

(GILD) - Get Report

. Analysts surveyed by Thomson Reuters are looking for a profit of 49 cents a share on $1.32 billion in revenue. Gilead shares were up 5.9% ahead of quarterly results.

Elsewhere, Brean Murray and Merriman Curhan Ford initiated coverage on multiple small- to mid-cap health-care stocks.

Brean Murray began coverage on

Mentor

( MNT) with a hold rating. Shares were off by 1.5% at $15.82.

The firm also picked up coverage on

Xtent

(XTNT) - Get Report

,

NuVasive

(NUVA) - Get Report

and

Hansen Medical

(HNSN)

with buy ratings. Xtent shares were up 9.8%, and NuVasive gave up 2.2%. Hansen Medical gained 6.6%.

Meanwhile, Merriman Curhan Ford started

Dendreon

(DNDN)

with a sell rating. The stock was down 1.7%, at $80.06. The firm began coverage on

Ariad Pharma

(ARIA)

with a neutral rating. Shares rose 7.3% to $1.61.

Last, it gave

Exelixis

(EXEL) - Get Report

,

Sangamo

(SGMO) - Get Report

and

Oncolytics

(ONCY) - Get Report

all buy ratings. Exelixis added 2.4%, Sangamo shares were down 1.1%, and Oncolytics tacked on 0.8%.