Xencor, Inc. (NASDAQ: XNCR), a clinical-stage biopharmaceutical
company developing engineered antibodies and cytokines for the
treatment of cancer and autoimmune diseases, today announced
additional clinical data from expansion cohorts in its Phase 1
study of plamotamab, a CD20 x CD3 bispecific antibody, in patients
with relapsed or refractory non-Hodgkin lymphomas. Data will be
presented by Krish Patel, M.D., Director of the Lymphoma Program at
Swedish Cancer Institute, in a poster session today from 6:00 p.m.
to 8:00 p.m. CST at the 64th American Society of Hematology (ASH)
Annual Meeting in New Orleans, Louisiana.
“Patients with non-Hodgkin lymphomas need further therapy
options which can be efficacious, well-tolerated and importantly,
administered in a variety of settings,” said Dr. Patel. “In the
Phase 1 monotherapy study of plamotamab, the recommended
intravenous dose was well tolerated, and we are encouraged by the
responses observed in the study. This was a cohort of patients that
were heavily pretreated, enriched with adverse prognostic factors,
and included poor risk histology, such as high-grade B cell
lymphoma and activated B-cell DLBCL.”
“Our strategy is to develop plamotamab as part of multiple
highly active chemotherapy-free regimens across B-cell cancers.
Xencor’s first combination study, evaluating plamotamab with
tafasitamab plus lenalidomide, is enrolling patients with advanced,
aggressive lymphoma. Importantly, we are engineering novel B-cell
targeted CD28 bispecific antibodies that may selectively enhance
T-cell cytotoxic activity,” said Allen Yang, M.D., Ph.D., senior
vice president and chief medical officer at Xencor. “Additionally,
patients enrolling to the ongoing Phase 1 monotherapy study will
now receive subcutaneous doses of plamotamab.”
At data cut off on August 24, 2022, 44 patients with relapsed or
refractory non-Hodgkin lymphoma (NHL) had been enrolled before June
30, 2022 and received the recommended dose. Patients had a median
age of 69 years and had received a median of 4 prior therapies. At
baseline, 86% had advanced stage III or IV disease. Additionally,
50% of patients received CAR-T as a prior therapy.
The primary disease at enrollment for these patients was diffuse
large B-cell lymphoma (DLBCL; n=26), high-grade B-cell lymphoma
(HGBCL; n=6), follicular lymphoma (FL; n=10), and other lymphoma
(n=2).
Safety Analysis
The safety profile of plamotamab was consistent with previous
results. The most common Grade 3 or 4 treatment-emergent adverse
events (AEs) across all patients were neutropenia (25.0%), anemia
(15.9%) and lymphopenia (11.4%). Grade 3 immune effector
cell-associated neurotoxicity syndrome was observed in one patient
(2.3%). AEs leading to plamotamab discontinuation occurred in nine
patients (20.5%), including four patients (9.1%) who discontinued
due to COVID-19. Cytokine release syndrome (CRS), the most common
AE, was observed in 70.5% of patients, and no patients experienced
Grade 3 or 4 CRS.
Efficacy Analysis
The efficacy analysis included both evaluable and
intent-to-treat (ITT) patient populations. Responses were assessed
based on the Lugano Classification.
In the efficacy evaluable population of patients with DLBCL or
HGBCL, the overall response rate (ORR) was 52.0% (13/25), and the
complete response rate was 24.0% (6/25). For patients who received
prior CAR-T therapy, the ORR was 50.0% (8/16), and the CR rate was
25.0% (4/16). In the ITT population, the ORR was 43.8% (14/32), and
the complete response rate was 18.8% (6/32). The median duration of
response (mDOR) for both populations was 126 days.
In the efficacy evaluable population of patients with FL, the
ORR was 87.5% (7/8), and the CR rate was 50.0% (4/8). In the ITT
population, the ORR was 80.0% (8/10), and the CR rate was 40.0%
(4/10). The mDOR for both populations had not been reached.
Dose Exposure-Response Analysis
An analysis of the plamotamab exposure-response (ER)
relationship from the dose-escalation portion of the Phase 1 study
examined IL-6 levels, CRS incidence, high-grade AEs and overall
response. First-dose CRS was related to maximum plamotamab
concentration (Cmax). The probability of CRS with step-up dosing,
however, was better modeled using the magnitude of the step-up
increment, as measured by the ratio of Cmax after dosing to the
concentration prior to that dosing (Ctrough). Once the target dose
was reached, there was no relationship of exposure to high-grade
CRS. This analysis indicates the potential for a wide therapeutic
window at the target dose and provides guidance for improving
dosing regimens in future clinical studies of plamotamab.
The poster will be archived under "Events & Presentations"
in the Investors section of the Company's website located at
www.xencor.com.
About Plamotamab
Plamotamab is an investigational tumor-targeted XmAb® bispecific
antibody that contains both a CD20 binding domain and a cytotoxic
T-cell binding domain (CD3). CD20 is highly expressed across a
range of B-cell tumors, including non-Hodgkin lymphoma (NHL).
Engagement of CD3 by plamotamab activates T cells for highly potent
and targeted killing of CD20-expressing tumor cells.
Safety and anti-tumor activity from the ongoing Phase 1 clinical
study has indicated that plamotamab was generally well tolerated
and demonstrated encouraging clinical activity as a monotherapy.
Plamotamab is also being evaluated in a Phase 2 study, in
combination with tafasitamab plus lenalidomide, in patients with
relapsed or refractory diffuse large B-cell lymphoma. The study
consists of two parts, a safety run-in intended to establish the
safety of the triple combination and a two-arm, open-label cohort
where patients will be randomized to receive either the triple
combination or tafasitamab plus lenalidomide.
Xencor has entered an exclusive collaboration and worldwide
license agreement with Janssen Biotech, Inc. (Janssen) to develop
and commercialize plamotamab and novel XmAb B-cell targeting
bispecific antibodies that are designed to conditionally activate T
cells through co-stimulation.
About Xencor
Xencor is a clinical-stage biopharmaceutical company developing
engineered antibodies and cytokines for the treatment of patients
with cancer and autoimmune diseases. More than 20 candidates
engineered with Xencor's XmAb® technology are in clinical
development, and three XmAb medicines are marketed by partners.
Xencor's XmAb engineering technology enables small changes to a
protein's structure that result in new mechanisms of therapeutic
action. For more information, please visit www.xencor.com.
Forward-Looking Statements
Certain statements contained in this press release may
constitute forward-looking statements within the meaning of
applicable securities laws. Forward-looking statements include
statements that are not purely statements of historical fact, and
can generally be identified by the use of words such as
“potential,” “can,” “will,” “plan,” “may,” “could,” “would,”
“expect,” “anticipate,” “seek,” “look forward,” “believe,”
“committed,” “investigational,” and similar terms, or by express or
implied discussions relating to clinical trial data for plamotamab
generally, planned clinical trials, the quotations from Xencor
management and study investigator and other statements that are not
purely statements of historical fact. Such statements are made on
the basis of the current beliefs, expectations, and assumptions of
the management of Xencor and are subject to significant known and
unknown risks, uncertainties and other factors that may cause
actual results, performance or achievements and the timing of
events to be materially different from those implied by such
statements, and therefore these statements should not be read as
guarantees of future performance or results. Such risks include,
without limitation, the risks associated with the process of
discovering, developing, manufacturing and commercializing drugs
that are safe and effective for use as human therapeutics and other
risks, including the ability of publicly disclosed preliminary
clinical trial data to support continued clinical development and
regulatory approval for specific treatments, in each case as
described in Xencor's public securities filings. For a discussion
of these and other factors, please refer to Xencor's annual report
on Form 10-K for the year ended December 31, 2021 as well as
Xencor's subsequent filings with the Securities and Exchange
Commission. You are cautioned not to place undue reliance on these
forward-looking statements, which speak only as of the date hereof.
This caution is made under the safe harbor provisions of the
Private Securities Litigation Reform Act of 1995, as amended to
date. All forward-looking statements are qualified in their
entirety by this cautionary statement and Xencor undertakes no
obligation to revise or update this press release to reflect events
or circumstances after the date hereof, except as required by
law.
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version on businesswire.com: https://www.businesswire.com/news/home/20221212005254/en/
For Investors: Charles Liles cliles@xencor.com 626-737-8118
For Media: Jason I. Spark Evoke Canale
jason.spark@evokegroup.com 619-849-6005
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