Maintaining the quality of vaccines through the use of standards: Current challenges and future opportunities.

An international hybrid meeting held 21-22 June 2023 in Ottawa, Canada brought together regulators, scientists, and industry experts to discuss a set of principles and best practices in the development and implementation of standards. Although the use of international standards (ISs) and international units (IUs) has been an essential part of ensuring human and animal vaccine quality in the past decades, the types and uses of standards have expanded with technological advances in manufacture and testing of vaccines. The needs of stakeholders are evolving in response to the ever-increasing complexity, diversity, and number of vaccine products as well as increasing efforts to replace animal-based potency tests with in vitro assays that measure relevant quality attributes. As such, there must be a concomitant evolution in the design and implementation of both international and in-house standards. Concomitantly, greater harmonization of regulatory expectations must be achieved through collaboration with standard-setting organizations, national control laboratories and manufacturers. Stakeholders provided perspectives on challenges and several recommendations emerged as essential to advancing agreed upon objectives.

Assessing parallelism prior to determining relative potency.

In the course of preparing a revision to Chapter (111) of the U.S. Pharmacopeia, the revision committee came to a unanimous agreement that the method for assessing parallelism that is currently presented in (111) and in the European Pharmacopeia's Chapter 5.3 is flawed and should be replaced. The symptoms are that perfectly acceptable assay results may fail due to good precision and that obviously faulty assay results may pass due to poor precision. The flaw is that the wrong statistical technique has been used. We propose an alternative approach based on the equivalence testing paradigm that does not have these shortcomings. Equivalence testing requires the establishment of equivalence limits. Specific approaches for establishing equivalence limits are discussed.

Phase 1 trial of FVIII gene transfer for severe hemophilia A using a retroviral construct administered by peripheral intravenous infusion.

In a phase 1 dose escalation study, 13 subjects with hemophilia A received by peripheral intravenous infusion a retroviral vector carrying a B-domain-deleted human factor VIII (hFVIII) gene. Infusions were well tolerated. Tests for replication competent retrovirus have been negative. Polymerase chain reaction (PCR) analyses demonstrate the persistence of vector gene sequences in peripheral blood mononuclear cells in 3 of 3 subjects tested. Factor VIII was measured in serial samples using both a one-stage clotting assay and a chromogenic assay. While no subject had sustained FVIII increases, 9 subjects had FVIII higher than 1% on at least 2 occasions 5 or more days after infusion of exogenous FVIII, with isolated levels that ranged from 2.3% to 19%. Pharmacokinetic parameters of exogenous FVIII infused into subjects 13 weeks after vector infusion showed an increased half-life (T1/2; P <.02) and area under the curve (AUC, P <.04) compared with prestudy values. Bleeding frequency decreased in 5 subjects compared with historical rates. These results demonstrate that this retroviral vector (hFVIII(V)) is safe and, in some subjects, persists more than a year in peripheral blood mononuclear cells, with measurable factor VIII levels and with increased available FVIII activity (increased T1/2 and AUC) after infusion of exogenous FVIII concentrate.