GlaxoSmithKline has discontinued development of a mid-stage antibiotic licensed from Anacor Pharmaceuticals for the treatment of complicated urinary tract infections.

The news is not a huge surprise given that the drugs major suspended four clinical trials of GSK2251052 in February. That move was due to the identification of microbiological findings of resistance in a small number of patients in a Phase IIb trial.

Since then, GSK has conducted additional pre-clinical research and "after assessing various options" has elected to discontinue further development of GSK2251052 and return all rights to Anacor.

The companies originally linked up in July 2010 when Anacor banked a $15 million initial fee and was eligible to receive development milestones up to $75 million, commercial milestones up to $175 million and royalties.

However, Anacor noted that GSK is continuing to fund the former’s research activities in tuberculosis. Its two lead product candidates are  tavaborole, a topical antifungal for the treatment of onychomycosis and AN2728, a topical anti-inflammatory PDE-4 inhibitor for atopic dermatitis and psoriasis.