Evolution of a Green and Sustainable Manufacturing Process for Belzutifan: Part 4─Applications of Process Analytical Technology in Heterogeneous Biocatalytic Hydroxylation

Belzutifan has been approved recently by the U.S. Food and Drug Administration (FDA) for treating patients with certain types of Von Hippel-Lindau (VHL) disease-associated tumors. Although a commercial synthetic process has been established to make belzutifan, a further optimized process with fewer steps, improved cost-effectiveness, and a smaller environmental footprint is always in demand. In the new commercial synthetic route, a single-step biocatalytic hydroxylation reaction was used to replace the five chemical steps required in the previous route. In developing this new biocatalytic reaction, multiple process analytical technologies (PATs), such as Fourier transform infrared spectroscopy (FTIR), in situ imaging, dissolved oxygen monitoring, etc., were used to track important reaction parameters under complex reaction conditions (e.g., multiphases and dense slurry). With quantitative modeling, the product concentration and yield can be tracked in real time based on FTIR. This is particularly important for dense slurry reactions, for which offline sampling becomes challenging due to the sample inhomogeneity. In-depth mechanistic insights were also obtained using PATs revealing reaction kinetics controlled by different mass transfer limited processes, as well as the unique role of 1-octanol. These PAT-enabled capabilities for reaction tracking and understanding facilitated process development from the laboratory to the pilot scale and ensured a robust process for the hydroxylation reaction.