A Study to Evaluate the Safety and Efficacy of GS-6624 (Formerly AB0024) in Patients With Idiopathic Pulmonary Fibrosis

The primary objective of this study is to characterize the safety, tolerability, and PK of
GS-6624 after multiple IV administrations in patients with IPF. The secondary objectives are
to evaluate the formation of anti-GS-6624 antibodies and to measure the effects of GS-6624
on FVC, DLCO, and SGRQ score. A total of 48 patients will be enrolled. In the double-blind
phase (Part A), a total of 18 patients were enrolled at 3 dose levels. Part A was completed
in October 2011.

In Part B, 30 patients will be enrolled at 2 dose levels. Part B is open-label and is
currently enrolling.

Inclusion Criteria:

1. Acceptable results on pulmonary function tests

2. At rest oxygen saturation ≥90% on room air

3. Adequate organ function

Exclusion Criteria:

1. High resolution computer tomography pattern showing emphysema that is greater than
fibrosis

2. Acceptable results on whole body plethysmography

3. History of clinically significant hepatic or renal disease

4. Poorly controlled or severe diabetes mellitus

5. Use of systemic immunosuppressants within 28 days of GS-6624 infusion