Changes in raw material supplier represents a major consideration for life-cycle management and proactive monitoring is recommended. A case study is presented with Ceramic Hydroxyapatite (CHT), a common biopurification media consisting of calcium phosphate. CHT is known to adsorb proteins at calcium and phosphate sites on its matrix, and elutes proteins bound to calcium sites via an increase in phosphate concentration. During late stage process development of a biomolecule, pyrophosphate present in a raw material, anhydrous potassium phosphate dibasic, was found to reduce yield. Pyrophosphate is known to readily bind to CHT, likely resulting in this yield loss. To mitigate this risk, a pyrophosphate specification of &lt; 450 ppm was established for this raw material. The anhydrous phosphate raw material utilized in this bioprocess is susceptible to pyrophosphate generation during its manufacturing process due to the high temperature required to convert phosphate from its hydrated to anhydrous form. Pyrophosphate concentration cannot directly be controlled at the raw material vendor, resulting in an effort to develop an assay to measure concentration in the raw material. Ultimately, an IC HPLC assay was developed to measure pyrophosphate concentration with a limit of detection of 50 ppm. To establish the assay specification, CHT studies were executed using a laboratory scale column. Pyrophosphate was added to conditioning and wash buffers at varying levels across experimental conditions, and the resulting yields were measured. A maximum pyrophosphate concentration of &lt;450 ppm in the raw material was selected for the specification on the basis of these results, below the concentration at which an impact to yield could be expected. The pyrophosphate assay established will be transferred to the potassium phosphate dibasic vendor to ensure robust supply of material meeting CHT process requirements. Development and implementation of this assay demonstrates an effective approach to control a raw material impurity.

Enabling robust CHT purification: Implementation of a raw material specification for control of pyrophosphate impurity

2019 Spring National Meeting

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