Merck & Co has expanded its presence in HIV by signing two licensing deals and unveiling plans for a mid-stage study for one of its own drugs.

First up, a deal has been signed with Chimerix giving the US major access to  CMX157, the former’s lipid acyclic nucleoside phosphonate which has completed Phase I. Cashwise, Chimerix will receive $17.5 million upfront and be eligible to receive up to $151 million in milestones, plus royalties on future sales.

Merck has also signed an agreement with Japan's Yamasa Corp to develop EFdA (4’-ethynyl-2-fluoro-2’-deoxyadenosine), a nucleoside reverse transcriptase inhibitor candidate in preclinical studies which has shown antiviral activity toward highly-resistant HIV strains. The company will pay an upfront fee and future milestone payments in return for exclusive worldwide rights; financial details were not disclosed.

The New Jersey-based firm also disclosed that it intends to initiate a Phase II study for MK-1439, its own next-generation non-nucleoside reverse transcriptase inhibitor. The trial will evaluate the drug in HIV positive, treatment-naive patients compared to Bristol-Myers Squibb's Sustiva (efavirenz), both in combination with Gilead Sciences' Truvada (emtricitabine/tenofovir).

Robin Isaacs, head of infectious disease clinical research at Merck Research Laboratories, said that "despite the tremendous advances made over the past 20 years, there remains considerable unmet need in the treatment of HIV infection". The company nodded that it is looking at "at least five distinct targets and have several HIV compounds in development".