ASTM E3042-16

3.1 Rodent-derived cell lines are widely used in the production of biopharmaceutical drugs such as mAbs and Fc fusion proteins. These cell lines have been shown to contain genes encoding endogenous retroviral-like particles or endogenous retrovirus. Despite the lack of evidence for an association between such rodent retroviruses and disease in humans, the potential contamination of human therapeutics raises safety concerns for biopharmaceutical drugs. Additionally, adventitious agents such as viruses can be introduced into a biopharmaceutical drug substance manufacturing process from other sources, and potential safety issues can be attributed to these potential unknowns. For these reasons, effective viral clearance is an essential aspect of an integrated approach combining safety testing and process characterization which ensures virus safety for biopharmaceutical drug products made using rodent cell lines.

3.2 Solvent/detergent inactivation has been widely used for decades to inactivate enveloped viruses in blood plasma derived biopharmaceutical therapies (1-3).3 Solvent/detergent systems using the detergents Triton X-100 or Polysorbate 80 along with the organic solvent tri(n-butyl)phosphate (TNBP) have been used to inactivate enveloped viruses by disrupting the viral envelope thereby reducing the ability of the enveloped virus to attach to and then infect the host cell (4 and 5).

3.3 Most manufacturers of mAbs, recombinant proteins, and Fc fusion proteins have focused on viral inactivation methods using the detergent Triton X-100 or Polysorbate 80 in the absence of TNBP (6), which can interfere with subsequent bioprocessing steps. The ability of the detergents alone to inactivate retroviruses has been demonstrated in monoclonal antibodies produced in rodent-derived cell lines (6-9). At a 2011 workshop devoted to viral clearance steps used in bioprocessing (7), investigators from one firm showed incubation with 0.2 % Triton X-100 for 60 min of hold time at ambient temperature inactivated >5 log₁₀ of X-MuLV across four separate mAbs in cell culture matrices.

1.1 This practice assures effective inactivation of ≥4 log_{1.2 The parameters specified for this practice are clarification, Triton X-100 detergent concentration, hold time, pH, and inactivation temperature.}

1.3 This practice can be used in conjunction with other clearance or inactivation unit operations that are orthogonal to this inactivation mechanism to achieve sufficient total process clearance or inactivation of rodent retrovirus.

1.4 This detergent inactivation step is performed on a clarified, cell-free intermediate of the monoclonal antibody or IgG Fc fusion protein.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.