Shares of drug makers Pfizer Inc. /zigman2/quotes/202877789/delayed PFE +0.07% and Eli Lilly & Co. /zigman2/quotes/200106384/delayed LLY -0.02% declined in the extended session Thursday after the companies said a clinical study of an osteoarthritis drug didn't meet certain goals. Pfizer shares declined 1% after hours, following a 1.3% decline to close at $39.38 in the regular trading session. Lilly shares fell 1.9% after hours, following a 1.1% close lower at $115.20. The companies said that a late-stage study of their drug tanezumab at 5 mg did not show a statistically significant improvement in overall osteoarthritis symptoms compared with nonsteroidal anti-inflammatory drugs. A 2.5 mg dose did not show a statistically significant improvement in pain, physical function or patients' overall assessment, the companies said. "We are analyzing these findings in the context of the recent Phase 3 results as we assess potential next steps for tanezumab," said Ken Verburg, Pfizer's tanezumab development team leader, in a statement. "We plan to review the totality of data from our clinical development program for tanezumab with regulatory authorities."