Advancing Biologics Development Programs with Legacy Cell Lines: Advantages and Limitations of Genetic Testing for Addressing Clonality Concerns Prior to Availability of Late Stage Process and Product Consistency Data

Abstract

The bioprocessing industry uses recombinant mammalian cell lines to generate therapeutic biologic drugs. To ensure consistent product quality of the therapeutic proteins, it is imperative to have a controlled production process. Regulatory agencies and the biotechnology industry consider cell line "clonal origin" an important aspect of maintaining process control. Demonstration of clonal origin of the cell substrate, or production cell line, has received considerable attention in the past few years, and the industry has improved methods and devised standards to increase the probability and/or assurance of clonal derivation. However, older production cell lines developed before the implementation of these methods, herein referred to as "legacy cell lines," may not meet current regulatory expectations for demonstration of clonal derivation. In this article, the members of the IQ Consortium Working Group on Clonality present our position that the demonstration of process consistency and product comparability of critical quality attributes throughout the development life cycle should be sufficient to approve a license application without additional genetic analysis to support clonal origin, even for legacy cell lines that may not meet current day clonal derivation standards. With this commentary, we discuss advantages and limitations of genetic testing methods to support clonal derivation of legacy cell lines and wish to promote a mutual understanding with the regulatory authorities regarding their optional use during early drug development, subsequent to Investigational New Drug (IND) application and before demonstration of product and process consistency at Biologics License Applications (BLA) submission.

Retrospective assessment of clonal origin of cell lines

“…[2][3][4][5][6] The balance between monoclonality and alternate control strategies required for a manufacturing cell line is an ongoing discussion. 2,6,7 A key consideration is the genetic plasticity of CHO cells resulting in an MCB derived from a single progenitor cell being a heterogeneous population. [8][9][10][11][12] Typically the assurance for a claim of monoclonality requires data supporting a probability equivalent to two rounds of limiting dilution at sufficiently low seeding.…”

“…Recently regulatory authorities have required that data to support a claim of “monoclonality.” If data is not sufficient for such a claim, further analysis to give assurance of monoclonality and/or augmented control strategy to ensure consistent product quality is required 2‐6 . The balance between monoclonality and alternate control strategies required for a manufacturing cell line is an ongoing discussion 2,6,7 . A key consideration is the genetic plasticity of CHO cells resulting in an MCB derived from a single progenitor cell being a heterogeneous population 8‐12 .…”