2023 White Paper on Recent Issues in Bioanalysis: ISR for ADA Assays, the Rise of dPCR vs qPCR, International Reference Standards for Vaccine Assays, Anti-AAV TAb Post-Dose Assessment, NanoString Validation, ELISpot as Gold Standard (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Biotherapeutics Immunogenicity & Risk Assessment; ADA/NAb Assay/Reporting Harmonization).

The 17th Workshop on Recent Issues in Bioanalysis (17th WRIB) took place in Orlando, FL, USA on June 19-23, 2023. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 17th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week to allow an exhaustive and thorough coverage of all major issues in bioanalysis of biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on "EU IVDR 2017/746 Implementation and impact for the Global Biomarker Community: How to Comply with these NEW Regulations" and on "US FDA/OSIS Remote Regulatory Assessments (RRAs)" were the special features of the 17th edition. As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues. This 2023 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2023 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity. Part 1A (Mass Spectrometry Assays and Regulated Bioanalysis/BMV), P1B (Regulatory Inputs) and Part 2 (Biomarkers, IVD/CDx, LBA and Cell-Based Assays) are published in volume 16 of Bioanalysis, issues 8 and 9 (2024), respectively.

Anti-drug Antibody Magnitude and Clinical Relevance Using Signal to Noise (S/N): Bococizumab Case Study.

Historically, the biopharmaceutical industry has used titer to characterize the magnitude of an anti-drug antibody (ADA) response. While reporting levels of antibodies in terms of titer is generally understood and accepted by regulatory and medical communities, titer values are inherently variable given the multiple serial dilutions and reporting a value either directly before or interpolated at the assay cut point on the lower plateau of the assay curve range. Using S/N is an appealing alternative approach to titer as it simplifies analysis with less dilutions, significantly reducing testing, time, and resources and provides a more precise value potentially differentiating low-level ADA responses. Current bridging electrochemiluminescence (ECL) ADA assays using Meso Scale Discovery (MSD) platform are also significantly more sensitive and drug tolerant with wider assay ranges compared to historic ELISA platforms; therefore, ADA response based on S/N may help differentiate and identify those ADA samples that are more likely to be clinically relevant. Bococizumab is a humanized monoclonal antibody targeting proprotein convertase subtilisin-kexin type 9 (PCSK9), which reduces plasma levels of low-density lipoprotein (LDL) cholesterol. Bococizumab was discontinued during Phase 3 clinical development based in part on the high rate of ADA and wide variation in LDL cholesterol responses among patients. The impact of anti-bococizumab antibodies on pharmacokinetic (PK) and pharmacodynamic (PD) endpoints was originally assessed using titer. Retrospective analysis of anti-bococizumab ADA responses using S/N ratios illustrates that S/N is an acceptable alternative to titer for characterizing the magnitude of ADA response and interpretation of clinically relevant ADA.

Neutralizing Antibody Validation Testing and Reporting Harmonization.

Evolving immunogenicity assay performance expectations and a lack of harmonized neutralizing antibody validation testing and reporting tools have resulted in significant time spent by health authorities and sponsors on resolving filing queries. A team of experts within the American Association of Pharmaceutical Scientists' Therapeutic Product Immunogenicity Community across industry and the Food and Drug Administration addressed challenges unique to cell-based and non-cell-based neutralizing antibody assays. Harmonization of validation expectations and data reporting will facilitate filings to health authorities and are described in this manuscript. This team provides validation testing and reporting strategies and tools for the following assessments: (1) format selection; (2) cut point; (3) assay acceptance criteria; (4) control precision; (5) sensitivity including positive control selection and performance tracking; (6) negative control selection; (7) selectivity/specificity including matrix interference, hemolysis, lipemia, bilirubin, concomitant medications, and structurally similar analytes; (8) drug tolerance; (9) target tolerance; (10) sample stability; and (11) assay robustness.

A sensitive LC-MS/MS assay for the determination of dextromethorphan and metabolites in human urine--application for drug interaction studies assessing potential CYP3A and CYP2D6 inhibition.

The commonly used antitussive dextromethorphan can be used to simultaneously assess potential cytochrome P450 3A (CYP3A) and CYP2D6 inhibition during drug development. The metabolism of dextromethorphan to dextrorphan and subsequently to 3-hydroxymorphinan are via the 2D6 pathway, while the metabolism of dextromethorphan to 3-methoxymorphinan is via the 3A pathway. A sensitive and specific LC-MS/MS assay has been developed to determine the human urine concentrations of dextromethorphan and three metabolites (dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan) in support of drug interaction studies. Urine samples (0.5 ml), after enzymatic hydrolysis of the conjugates and containing 3-ethylmorphine as an internal standard, were extracted with chloroform under basic conditions. Following concentration and reconstitution, the samples were analyzed by LC-MS/MS. The assay was linear over the range of 5.00-500 ng/ml for dextromethorphan and 3-methoxymorphinan; and 200-3000 ng/ml for dextrorphan and 3-hydroxymorphinan using a Perkin-Elmer Sciex triple quadrupole mass spectrometer (API 300). The intra- and inter-day relative standard deviation (RSD) across three validation runs over the entire concentration range for all analytes was less than 15%. Accuracy determined at three or four concentrations (9.00, 200, and 400 ng/ml for dextromethorphan and 3-methoxymorphinan; 250, 400, 1300 and 2500 ng/ml for dextrorphan and 3-hydroxymorphinan) ranged between 96.3 and 113.8%. The stability of analytes in urine was demonstrated for 9 months at -20 degrees C, 24 h under ambient conditions and for up to three freeze/thaw cycles. The method described herein is suitable for the rapid and efficient measurement of dextromethorphan and different metabolites to estimate potential CYP3A inhibition by drug candidates and for screening of extensive and poor metabolizers of CYP2D6 in the heterogeneous population. The method has subsequently been validated on a Sciex API 3000 with lower limit of quantitation; 1.00 ng/ml for dextromethorphan and 3-methoxymorphinan; 60.0 ng/ml for dextrorphan and 100 ng/ml for 3-hydroxymorphinan.

Safety and pharmacology of ponezumab (PF-04360365) after a single 10-minute intravenous infusion in subjects with mild to moderate Alzheimer disease.

OBJECTIVE: Ponezumab (PF-04360365) is a humanized anti-amyloid beta (Aß) monoclonal antibody designed for treatment of Alzheimer disease (AD). A single 2-hour intravenous infusion of 0.1 to 10 mg/kg was previously shown to be safe and well tolerated in subjects with mild to moderate AD, with measurable effects on plasma and cerebrospinal fluid Aß. This phase I, dose-escalation, open-label study evaluated the safety, pharmacokinetics, and pharmacodynamics of a single 10-minute intravenous infusion. METHODS: Subjects with mild to moderate AD received ponezumab 1 mg/kg (n = 3), 3 mg/kg (n = 3), 5 mg/kg (n = 4), or 10 mg/kg (n = 5). They were followed up as outpatients for 6 months. RESULTS: All subjects completed the trial. Ponezumab was safe and well tolerated with no deaths, withdrawals, or drug-related moderate, severe, or serious adverse events. Mild drug-related adverse events included headache (3 patients) and lethargy and hypoesthesia (both in 1 patient). No infusion reactions, clinically meaningful laboratory abnormalities, vital sign changes, electrocardiographic changes, or antidrug antibodies were detected. There was no evidence of brain microhemorrhage, vasogenic edema, encephalitis, or other imaging abnormality. Cognitive function showed no treatment-related trends. Ponezumab displayed approximately dose-proportional increases in plasma exposure. Steady-state volume of distribution was 113 to 172 mL/kg, clearance was 2.7 to 3.0 mL/d/kg, and terminal half-life was 35 to 52 days. Plasma maximum observed concentration and the area under the plasma concentration-time profile from time 0 extrapolated to infinite time of Aß(1-x) and Aß(1-40) increased dose-dependently. CONCLUSIONS: Administration of ponezumab as a 10-minute infusion was safe and well tolerated and produced effects on plasma Aß species comparable with a 2-hour infusion. Shorter infusions may provide more flexibility, comfort, and convenience for patients and caregivers.

Safety and pharmacology of a single intravenous dose of ponezumab in subjects with mild-to-moderate Alzheimer disease: a phase I, randomized, placebo-controlled, double-blind, dose-escalation study.

OBJECTIVES: Ponezumab is a humanized antiamyloid beta (Aß) monoclonal antibody designed to treat Alzheimer disease (AD). METHODS: This randomized, double-blind, single-dose-escalation study evaluated the safety, pharmacokinetics, and pharmacodynamics of 0.1, 0.3, 1, 3, and 10 mg/kg ponezumab (n = 4, 4, 4, 6, and 8, respectively) versus placebo (n = 11) after a 2-hour intravenous infusion in subjects with mild-to-moderate AD. Cerebrospinal fluid (CSF) samples were obtained from the 1- and 10-mg/kg groups at baseline and at day 29. The subjects were followed for 1 year. RESULTS: All subjects completed the trial. Ponezumab was well tolerated with no drug-attributed serious adverse events. The most common adverse events were upper respiratory tract infection, headache, and back pain, all mild to moderate. One subject (10 mg/kg) experienced a mild hypersensitivity reaction. Another subject (0.1 mg/kg) demonstrated slight enlargement of a preexisting midbrain lesion. Electrocardiography and laboratory values (including CSF) were unremarkable. No evidence of new microhemorrhage, vasogenic edema, or meningoencephalitis was noted. Plasma maximum observed concentration increased approximately dose proportionally, and the area under the plasma concentration-time profile from time zero extrapolated to infinite time (AUC(inf)) increased slightly more than dose proportionally. Mean terminal half-life was approximately 6 weeks. Two subjects (10 mg/kg) had measurable CSF ponezumab concentrations (~0.5% of plasma values) at day 29. Plasma Aß(1-x) and Aß(1-40) increased dose dependently, and mean CSF Aß(1-x) increased 38% from baseline with 10 mg/kg (P = 0.002 vs placebo). CONCLUSIONS: A 2-hour infusion of 0.1 to 10 mg/kg ponezumab was well tolerated in subjects with mild-to-moderate AD. Plasma pharmacokinetic profile was approximately linear. Plasma Aß increased with dose, and CSF Aß increased at the highest dose, suggesting that intravenous ponezumab alters central Aß levels.