On November 1, 2018 Xencor, Inc. (NASDAQ:XNCR), a clinical-stage biopharmaceutical company developing monoclonal antibodies for the treatment of autoimmune disease, asthma and allergic diseases, and cancer, reported that initial data from its ongoing Phase 1 dose-escalation study of XmAb14045, a CD123 x CD3 bispecific antibody, in patients with relapsed/refractory acute myeloid leukemia (AML) will be presented in an oral session at the 2018 American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting on Monday, December 3, 2018 (Press release, Xencor, NOV 1, 2018, View Source [SID1234530578]).

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Key Highlights from the Abstract

At data cut off on June 27, 2018, 63 patients with relapsed/refractory AML and one patient with B cell acute lymphoblastic leukemia had received XmAb14045. Patients had a median age of 61 years and were heavily pretreated, having a median of three prior therapies, and 30% (n=19/64) had undergone prior allogeneic stem cell transplantation.
No MTD was identified, and cytokine release syndrome (CRS) was the most common toxicity occurring in 49 of 64 patients (77%). Seven patients (11%) experienced Grade 3 or 4 CRS. CRS was generally manageable with premedication.
23% of evaluable patients with AML achieved either complete remission (CR) or CR with incomplete hematologic recovery (CRi) at the two highest dose levels studied to date (1.3 and 2.3 mcg/kg weekly; n=3/13).
Two patients with responses were bridged to stem cell transplantation, and the third was ineligible but remained in remission at 14+ weeks after initiating therapy.
"Initial results from the ongoing study of our lead bispecific antibody XmAb14045 in heavily pretreated patients with acute myeloid leukemia demonstrate that several patients achieved complete remissions," said Paul Foster, M.D., senior vice president and chief medical offer at Xencor. "XmAb14045 is a full-length immunoglobulin designed to be dosed intermittently. We continue to optimize dosing regimen as we advance the Phase 1 study."

Presentation Details

Abstract:

763

Title:

Complete Responses in Relapsed/Refractory Acute Myeloid Leukemia (AML) Patients on a Weekly Dosing Schedule of XmAb14045, a CD123 x CD3 T Cell-Engaging Bispecific Antibody: Initial Results of a Phase 1 Study

Presenter:

Farhad Ravandi, M.D., Professor of Medicine and Chief of Section of Developmental Therapeutics in the Department of Leukemia at the University of Texas – M.D. Anderson Cancer Center

Session:

616. Acute Myeloid Leukemia: Novel Therapy, excluding Transplantation: New Treatment Strategies

Date & Time:

Monday, December 3, 2018, 2:45 p.m. PST

Location:

Manchester Grand Hyatt San Diego, Seaport Ballroom F

The accepted abstract is now available on the ASH (Free ASH Whitepaper) conference website.

Analyst & Investor Event and Webcast Information
Xencor will host an analyst and investor event on Monday, December 3, 2018 from 8:00 to 10:00 p.m. PST with formal remarks at 8:30 p.m. PST. The event will feature a discussion of the data presented at ASH (Free ASH Whitepaper) and Xencor’s bispecific oncology pipeline. The event will be webcast live and can be accessed under Events & Presentations in the Investors section of www.xencor.com, where it will be archived for 30 days.

About XmAb14045
XmAb14045 is a tumor-targeted antibody that contains both a CD123 binding domain and a cytotoxic T-cell binding domain (CD3) in a Phase 1 clinical trial for the treatment of acute myeloid leukemia (AML) and other CD123-expressing hematologic 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 XmAb14045. CD123 is highly expressed on AML cells and leukemic stem cells, and it is associated with poorer prognosis in AML patients. Engagement of CD3 by XmAb14045 activates T cells for highly potent and targeted killing of CD123-expressing tumor cells.