GlaxoSmithKline PLC (GSK) said on Tuesday it would develop an HIV treatment with Japan’s Shionogi for use in regimens with dosing gaps of three months or more, as the drugmaker seeks to build on the success of its previous long-acting therapies. The British firm said it would pay Shionogi 20 million pounds ($27.36 million) upfront, with an additional 15 million pounds ($20.3 million) payable on completion of development milestones for the therapy S-365598, adding that human trials are expected by 2023. GSK’s ViiV Healthcare unit, in which Shionogi and Pfizer hold small stakes, will work with the Japanese drugmaker on the experimental treatment which prevents the HIV virus from duplicating by blocking an enzyme released by it. “We will continue this collaboration [with Shionogi] and explore the potential of S-365598 to anchor ViiV Healthcare’s pipeline beyond 2030,” said Kimberly Smith, head of R&D at the GSK unit. Gilead Sciences’ Truvada …