Glofitamab, a novel CD20xCD3, T-cell-engaging bispecific antibody, demonstrated single-agent activity in study NP30179, a first-in-human, phase 1 trial in relapsed/refractory B-cell non-Hodgkin lymphoma. Preclinical studies showed that glofitamab leads to T-cell activation, proliferation and tumor cell killing upon binding to CD20 on malignant cells. Here, we provide evidence of glofitamab's clinical activity, including pharmacodynamics, mode of action and factors associated with clinical response, by evaluating biomarkers in patient samples from the dose-escalation part of this trial. Patients enrolled in NP30179 received single-dose obinutuzumab pretreatment (1000 mg; Gpt) 7 days prior to intravenous glofitamab (5 µg-25 mg). Glofitamab treatment lasted ≤12 cycles once every 2 or 3 weeks. Blood samples were collected at predefined time points per clinical protocol; T-cell populations were evaluated centrally by flow cytometry, and cytokine profiles were analyzed. Immunohistochemical and genomic biomarker analyses were performed on tumor biopsies. Pharmacodynamic modulation was observed with glofitamab treatment including dose-dependent induction of cytokines, and T-cell margination, proliferation and activation in peripheral blood. Gene expression analysis of pre-treatment tumor biopsies indicated that tumor cell intrinsic factors like TP53 signaling are associated with resistance to glofitamab, but may also be interlinked with a diminished effector T-cell profile in resistant tumors and thus represent a poor prognostic factor per se. This integrative biomarker data analysis provides clinical evidence of glofitamab's mode of action, supports optimal biological dose selection, and will further guide clinical development. This trial was registered at www.clinicaltrials.gov as #NCT03075696.

The 15th edition of the Workshop on Recent Issues in Bioanalysis (15th WRIB) was held on 27 September to 1 October 2021. Even with a last-minute move from in-person to virtual, an overwhelmingly high number of nearly 900 professionals representing pharma and biotech companies, contract research organizations (CROs), and multiple regulatory agencies still eagerly convened to actively discuss the most current topics of interest in bioanalysis. The 15th WRIB included three Main Workshops and seven Specialized Workshops that together spanned 1 week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on biomarker assay development and validation (BAV) (focused on clarifying the confusion created by the increased use of the term “context of use” [COU]); mass spectrometry of proteins (therapeutic, biomarker and transgene); state-of-the-art cytometry innovation and validation; and critical reagent and positive control generation were the special features of the 15th edition. This 2021 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 2021 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 2) covers the recommendations on ISR for Biomarkers, Liquid Biopsies, Spectral Cytometry, Inhalation/Oral & Multispecific Biotherapeutics, Accuracy/LLOQ for Flow Cytometry. Part 1A (Endogenous Compounds, Small Molecules, Complex Methods, Regulated Mass Spec of Large Molecules, Small Molecule, PoC), Part 1B (Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine) and Part 3 (TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparability & Cut Point Appropriateness) are published in volume 14 of Bioanalysis, issues 9 and 11 (2022), respectively.

Despite significant recent improvements in the field of immunotherapy, cancer remains a heavy burden on patients and healthcare systems. In recent years, immunotherapies have led to remarkable strides in treating certain cancers. However, despite the success of checkpoint inhibitors and the advent of cellular therapies, novel strategies need to be explored to (1) improve treatment in patients where these approaches fail and (2) make such treatments widely and financially accessible. Vaccines based on tumor antigens (Ag) have emerged as an innovative strategy with the potential to address these areas. Here, we review the fundamental aspects relevant for the development of cancer vaccines and the critical role of dendritic cells (DCs) in this process. We first offer a general overview of DC biology and routes of Ag presentation eliciting effective T cell-mediated immune responses. We then present new therapeutic avenues specifically targeting Fc gamma receptors (FcγR) as a means to deliver antigen selectively to DCs and its effects on T-cell activation. We present an overview of the mechanistic aspects of FcγR-mediated DC targeting, as well as potential tumor vaccination strategies based on preclinical and translational studies. In particular, we highlight recent developments in the field of recombinant immune complex-like large molecules and their potential for DC-mediated tumor vaccination in the clinic. These findings go beyond cancer research and may be of relevance for other disease areas that could benefit from FcγR-targeted antigen delivery, such as autoimmunity and infectious diseases.

INTRODUCTION: Activated Tregs in the tumor micro-environment are correlated with poor outcomes, and are considered as key players in tumor immune-escape. So far, Treg depletion has not been successful in patients, either because adequate Treg depletion was not achieved or because Teff cells have either been impacted or depleted as well. RG6292 is the first anti-human CD25 antibody developed to specifically deplete human Tregs while preserving IL-2R STAT5 signaling and Teff activity. It has been optimized for ADCC and selective depletion of cells with high CD25 density (Treg). MATERIALS and METHODS: Adult patients with advanced solid tumors were given RG6292 i.v. Q3W as monotherapy (S1: NCT04158583) or in combination with atezolizumab 1200 mg Q3W (S2: NCT04642365) in a Ph1 dose escalation study. 76 pts have been treated at dose levels ranging from 0.3 mg to 165 mg in S1 and 48 pts at dose levels ranging from 0.3 mg to 160 mg in S2. In both studies a Bayesian logistic regression model with overdose control guided dose escalation was utilized. Data cutoff was May 27, 2022. Pharmacokinetic and pharmacodynamic analyses were undertaken in peripheral blood and tumor tissue. PK/PD modeling applied to Treg and Teff cells helped characterize and identify the optimal therapeutic window to ensure (1) relevant Treg depletion and (2) limited impact on T effector. RESULTS: RG6292 has a linear and time independent PK with no ADA detected. A Population PK-PD modeling approach was applied to Treg and Teff cells in the periphery. To predict the RG6292 effects in the tumor microenvironment (TME), the PK/PD relationships observed and characterized in the periphery for all cell subpopulations were considered the same, a tumor uptake factor of 15% was considered. At steady-state trough, a 70 mg Q3W dose was predicted to lead to 72% of patients with concentration above the Treg (%CD4) EC50 in tumor and 40% of patients with concentration above the Non-Treg (%CD4) EC50 in plasma. RG6292 induced a dose-dependent peripheral and intratumoral Treg depletion in on-treatment biopsies taken 28 days after initiation of treatment. Treatment did not appear to impact the number nor the functionality of intratumoral CD8 T cells nor any evident effect observed on PDL1 expression. In blood, stable levels of all other immune cells were observed after treatment. Moreover, in both studies a marginal increase of IFNg, CXCL10, IL-10, TNF was observed. No consistent gene expression alterations nor immune signatures could be observed when comparing BSL vs OT biopsies in S1. CONCLUSION: RG6292, consistent with its proposed mechanism of action, induces profound and preferential depletion of Treg cells over CD8+CD25+ in the periphery and in the TME at clinically safe doses between 35-70mg. Further development of RG6292 is currently being explored. Citation Format: Tamara Tanos, Kevin Smart, Valentina Gambardella, Kristoffer Rohrberg, Michael Ong, Maria Esperanza Rodriguez Ruiz, Jean-Pascal Machiels, Miguel Fernández Sanmamed, Josep Tabernero, Anna Spreafico, Daniel Renouf, Stephen Luen, Rachel Galot, Bernard Doger, Emiliano Calvo, Aung Naing, Samira Curdt, Nicolas Staedler, Mike Flores, Enrique Gómez Alcaide, Chiahuey Ooi, Michael Hettich, Sebastian Dziadek, Yuying Xie, Gabriel Schnetzler, Theresa Kolben, Linxinyu Xu, Vaios Karanikas, Christophe Boetsch. Pharmacokinetic/pharmacodynamic (PK/PD) relationships of the novel Treg depleter RG6292 in Phase Ia and Ib studies in patients with solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT176.