On November 6, 2019 Xencor, Inc. (NASDAQ: XNCR), a clinical-stage biopharmaceutical company developing engineered monoclonal antibodies for the treatment of cancer, autoimmune diseases, asthma and allergic diseases, reported that initial data from its ongoing Phase 1 dose-escalation study of XmAb13676, a CD20 x CD3 bispecific antibody, in patients with B-cell malignancies will be presented in a poster session during the 61st American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting in Orlando, Florida on Monday, December 9, 2019 (Press release, Xencor, NOV 6, 2019, View Source [SID1234550532]).

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"Initial results from dose-escalation cohorts demonstrate encouraging clinical activity in heavily pretreated patients with several subtypes of non-Hodgkin lymphoma, as well as chronic lymphocytic leukemia. The most common treatment-related adverse event has been fever. Cytokine release syndrome, the second most common adverse event, has been generally manageable with premedication," said Bassil Dahiyat, Ph.D., president and chief executive officer at Xencor.

Key Highlights from the Abstract

The abstract with accepted data from the study are available through the ASH (Free ASH Whitepaper) website. Updated results will be shared at the ASH (Free ASH Whitepaper) Annual Meeting.

At data cut off on June 28, 2019, 36 patients with relapsed/refractory non-Hodgkin’s lymphoma (r/r NHL) and 8 patients with relapsed/refractory chronic lymphocytic leukemia (r/r CLL) had received XmAb13676. The study was designed in two parts: Part A to establish an initial priming dose and Part B to escalate dosing on subsequent administration. Prophylactic treatment for cytokine release syndrome (CRS) was mandated prior to each administration of XmAb13676.
Patients with r/r NHL (n=36) had a median age of 61.5 years, a median of 3.5 prior therapies and had been diagnosed a median of 24.6 months prior to treatment. In the efficacy evaluable population and at doses ranging from 80 to 125 mcg/kg, objective responses were observed in 33% of patients (n=6/18), including 42% of DLBCL patients (n=5/12). CRS occurred in 42% of patients (n=15/36), and one patient receiving an initial dose of 125 mcg/kg experienced Grade 4 CRS. A priming dose of 45 mcg/kg was chosen for Part B.
Patients with r/r CLL (n=8) had a median age of 76 years, a median of 4.5 prior therapies and had been diagnosed a median of 76.1 months prior to treatment. There was one complete response (Richter transformation) in five patients treated at the 20 mcg/kg dose level, the highest dose administered in the ongoing Part A of the study. CRS occurred in 25% of patients (n=2/8), and one patient experienced Grade 3 CRS.
Presentation Details

Abstract: 4079
Title: Preliminary Safety and Anti-tumor Activity of XmAb13676, an Anti-CD20 x Anti-CD3 Bispecific Antibody in Patients with Relapsed/Refractory Non-Hodgkin’s Lymphoma and Chronic Lymphocytic Leukemia
Presenter: Krish Patel, M.D., Director of the Lymphoma Program at Swedish Cancer Institute
Session: 626. Aggressive Lymphoma (Diffuse Large B-Cell and Other Aggressive B-Cell Non-Hodgkin Lymphomas)—Results from Prospective Clinical Trials: Poster III
Date & Time: Monday, December 9, 2019, 6:00 p.m. – 8:00 p.m. EST
Location: Orange County Convention Center, Hall B
About XmAb13676

XmAb13676 is a tumor-targeted antibody that contains both a CD20 binding domain and a cytotoxic T-cell binding domain (CD3) in a Phase 1 clinical trial for the treatment of B-cell malignancies. An XmAb bispecific Fc domain serves as the scaffold for these two antigen binding domains and confers long circulating half-life, stability and ease of manufacture on XmAb13676. CD20 is highly expressed on B-cell tumors, including in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Engagement of CD3 by XmAb13676 activates T cells for highly potent and targeted killing of CD20-expressing tumor cells.