Joint Filer Name:

Three Arch Partners III, L.P.

Relationship to Issuer:

10% Owner

Address:

3200 Alpine Road, Portola Valley, CA 94028

Designated Filer:

Three Arch Management III, L.L.C.

Date of Event Requiring Statement:

03/03/2006

Issuer Name and Ticker or Trading Symbol:

Threshold Pharmaceuticals, Inc. (THLD)

Signature

Three Arch Partners III, L.P.

By:

Three Arch Management III, L.L.C. 

Its General Partner

By:

/s/ Barclay Nicholson

 Barclay Nicholson, Authorized Signatory

Joint Filer Name:

Three Arch Associates III, L.P.

Relationship to Issuer:

10% Owner

Address:

3200 Alpine Road, Portola Valley, CA 94028

Designated Filer:

Three Arch Management III, L.L.C.

Date of Event Requiring Statement:

03/03/2006

Issuer Name and Ticker or Trading Symbol:

Threshold Pharmaceuticals, Inc. (THLD)

Signature

Three Arch Associates III, L.P.

By:

Three Arch Management III, L.L.C.
Its General Partner 

By:

/s/ Barclay Nicholson

Joint Filer Name:

Mark A. Wan

Relationship to Issuer:

10% Owner

Address:

3200 Alpine Road, Portola Valley, CA 94028

Designated Filer:

Three Arch Management III, L.L.C.

Date of Event Requiring Statement:

03/03/2006

Issuer Name and Ticker or Trading Symbol:

Threshold Pharmaceuticals, Inc. (THLD)

Signature

Mark A. Wan

By:

/s/ Barclay Nicholson

 Barclay Nicholson, Authorized Signatory

Joint Filer Name:

Wilfred E. Jaeger

Relationship to Issuer:

10% Owner and Director

Address:

3200 Alpine Road, Portola Valley, CA 94028

Designated Filer:

Three Arch Management III, L.L.C.

Date of Event Requiring Statement:

03/03/2006

Issuer Name and Ticker or Trading Symbol:

Threshold Pharmaceuticals, Inc. (THLD)

Signature

Wilfred E. Jaeger

By:

/s/ Barclay Nicholson

 Barclay Nicholson, Authorized Signatory

Joint Filer Name:

Barclay Nicholson

Relationship to Issuer:

10% Owner

Address:

3200 Alpine Road, Portola Valley, CA 94028

Designated Filer:

Three Arch Management III, L.L.C.

Date of Event Requiring Statement:

03/03/2006

Issuer Name and Ticker or Trading Symbol:

Threshold Pharmaceuticals, Inc. (THLD)

Signature

Barclay Nicholson

By:

/s/ Barclay Nicholson

 Barclay Nicholson, Authorized Signatory