C.R.B. and genomic biomarker analyses were performed on tumor biopsy samples. 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 pretreatment tumor biopsy samples indicated that tumor cell intrinsic factors such as TP53 Loxistatin Acid (E64-C) signaling are associated with resistance to glofitamab, but they may also be interlinked with a diminished effector T-cell profile Loxistatin Acid (E64-C) in resistant tumors and thus represent a poor prognostic factor per se. This integrative biomarker data analysis provides clinical evidence regarding glofitamabs mode of action, supports optimal biological dose selection, and will further guide clinical development. This trial was registered at www.clinicaltrials.gov as #”type”:”clinical-trial”,”attrs”:”text”:”NCT03075696″,”term_id”:”NCT03075696″NCT03075696. Introduction The introduction of the monoclonal anti-CD20 therapeutic antibodies rituximab and obinutuzumab, in combination with chemotherapy, has significantly improved outcomes for patients with various types?of B-cell non-Hodgkin lymphoma (B-NHL) over the past 20 years.1 However, despite improved survival rates, nearly one-half of advanced-stage indolent B-NHL and aggressive lymphomas remain incurable.2,3 Thus, an unmet clinical need remains to further improve disease-free survival and ultimately achieve a cure in a greater fraction of patients with B-NHL. Significant advances into Loxistatin Acid (E64-C) cancer therapy have been made through the introduction of immune-checkpoint inhibitors. However, despite success in solid tumors, studies introducing checkpoint inhibitors?have shown disappointing efficacy in most B-NHL subtypes. Chimeric antigen receptor (CAR) T-cell therapies have shown that direct promotion of T cellCmediated cell death can lead to clinically meaningful remissions.4 However, this approach is complicated by significant challenges such as unpredictable toxicity events and clinical delays due to complex manufacturing and implementation requirements. Glofitamab is a bispecific T-cell engager with a 2:1 molecular format of anti-CD20:anti-CD3? binders.5 Through the formation of a transient immunologic synapse between CD20+ B Loxistatin Acid (E64-C) cells and CD3+ polyclonal T cells, T cells become activated, rapidly proliferate, and subsequently drive antilymphoma activity through T cellCmediated B-cell lysis. Furthermore, glofitamab exhibited significantly higher potency compared with other bispecific antibody formats in preclinical studies5 and may have an improved safety profile compared with CAR T-cell therapies.6 Study NP30179 (#”type”:”clinical-trial”,”attrs”:”text”:”NCT03075696″,”term_id”:”NCT03075696″NCT03075696) is a multicenter, open-label, phase 1, dose-escalation trial with single-agent glofitamab dosing after obinutuzumab (Gazyva/Gazyvaro; Genentech USA, South San Francisco, CA) pretreatment (Gpt) that reported FHF4 dose-dependent clinical activity in heavily pretreated patients with relapsed/refractory (R/R) aggressive or indolent B-NHL.6 Here, we present the blood and tissue biomarker analysis from the same phase 1 dose-escalation study, to characterize glofitamabs mode of action in the clinic and to explore response predictive factors. Methods Study design and patients Biomarker data are described for adult patients with histolopathologically confirmed R/R B-NHL enrolled in the fixed dose-escalation cohorts (parts 1 and 2) of Study NP30179, a multicenter, open-label, phase 1 trial investigating the safety, efficacy, tolerability, pharmacokinetic variables, and pharmacodynamic biomarkers of glofitamab after a fixed, single dose of Gpt. Patient inclusion and study design have been previously reported.6 Briefly, patients had at least 1 prior lymphoma treatment and at least 1 measurable target lesion of 1.5 cm. All enrolled patients received an initial 1000 mg dose of Gpt 7 days before receiving glofitamab. Dose escalation was guided by a Bayesian-modified continuous reassessment method.7 Glofitamab was administered at doses of 5 g to 25 mg for up to 12 cycles once every 2 or 3 3 weeks. Response assessments were conducted at baseline, after 2 and 5 cycles, at the end of treatment, and every 3 months until disease progression. Overall response rates, best Loxistatin Acid (E64-C) overall response, and complete response (CR) rates were evaluated per the Lugano classification.8 All patients provided written informed consent. The trial was approved by each centers ethics committee or institutional review board and was performed in compliance.