Engineered enzyme cuts cost, complexity to manufacture HIV drug lenacapavir

Directed evolution has enabled a high-performance biocatalyst to streamline synthesis of the HIV prevention drug lenacapavir which could reduce costs and expand access

A recent study has described a biocatalytic strategy that could transform the manufacture of lenacapavir, a long-acting antiretroviral medicine for HIV prevention. The research, led by professors Anthony Green and Nick Turner, both of the department of chemistry, Manchester Institute of Biotechnology at the University of Manchester, UK, has used directed evolution to engineer a bespoke aminotransferase enzyme capable of streamlining a critical step in the drug’s synthesis. The approach has the potential to reduce production costs substantially and to support broader global access.

Lenacapavir, which regulatory authorities including the US’ Food and Drug Administration and the UK’s Medicines and Healthcare Products Regulatory Agency have approved, is administered as a twice-yearly injectable to give prophylaxis pre-exposure to the virus. Clinical trials have shown very high levels of protection. And although royalty-free licensing agreements are already in place to allow for the manufacture of generics in 120 lower-income countries, the cost and complexity of producing the active pharmaceutical ingredient have remained a significant constraint to its availability.

At the centre of the challenge lies the molecule’s highly functionalised core, which consists of four distinct building blocks and incorporates a chiral amine. Chirality, which describes the existence of two mirror-image molecular forms, has critical importance in pharmaceutical chemistry because only one configuration typically delivers the desired biological effect. To synthesise this core with high selectivity using conventional multi-step chemical methods has proved both time-intensive and expensive.

The research team has addressed this bottleneck by turning to biocatalysis, which offers a route to perform complex transformations with high selectivity under milder conditions. They applied directed evolution, a technique that accelerates natural selection in the laboratory, to refine an aminotransferase enzyme capable of catalysing the formation of the target chiral amine. Using a strategy known as substrate walking, they began with an enzyme that exhibited no detectable activity on the desired substrate. Across eight iterative rounds of evolution – and after screening more than 12,000 variants – the team introduced ten mutations that progressively enhanced catalytic activity, stability and substrate compatibility.

The resulting enzyme demonstrated strong performance. It converted 98 per cent of the starting material and delivered a yield of more than 90 per cent, with an enantiomeric excess greater than 99 per cent, which confirmed that the correct chiral form was produced with high fidelity – enantiomerism is where pairs of molecules mirror each other but cannot be superimposed. The team also evaluated the enzyme under conditions that reflect industrial practice and has indicated that the process could scale effectively.

To understand the structural basis for these improvements, the researchers used X-ray crystallography to determine a high-resolution three-dimensional structure of the evolved enzyme. This analysis has shown how specific mutations reshaped the active site to accommodate the bulky ketone precursor and facilitate its conversion into the desired amine. Such structural insight is essential to inform future enzyme engineering projects and to extend the approach to other complex pharmaceutical targets.

“Our work has shown that it is possible to redesign enzymes to tackle one of the most challenging steps in lenacapavir synthesis, which opens a realistic path to more efficient manufacture,” the researchers stated, highlighting the translational potential of the platform.”

The team has begun to collaborate with industrial partners to translate the process from laboratory demonstration to full-scale biomanufacturing. In parallel, they have given the methodology open access, with the engineered enzyme available through the company Prozomix, which has offered free samples to organisations that wish to adopt the route.

If implemented at scale, the approach could enable a shorter, cleaner and more economical production pathway for lenacapavir. Such gains would align with global public health objectives to expand access to long-acting HIV prevention strategies, particularly in regions where cost remains a decisive barrier.

For further reading please visit: 10.1021/jacs.6c02519