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Molecular Templates Announces Presentations at the American Society of Hematology (ASH) 2019 Annual Meeting

AUSTIN, Texas, Dec. 09, 2019 (GLOBE NEWSWIRE) -- Molecular Templates, Inc., (MTEM) a clinical-stage biopharmaceutical  company focused on the discovery and development of the Company’s proprietary engineered toxin bodies (ETBs), which are differentiated, targeted, biologic therapeutics, today announced the presentations of two posters on its pipeline programs at the American Society of Hematology (ASH) 2019 Annual Meeting, taking place December 7-10, 2019 in Orlando, Florida.   One of these posters includes final results from the Phase 1/1b study of MT-3724, in subjects with relapsed/refractory (R/R) diffuse large b-cell lymphoma (DLBCL).

Poster Title: Monotherapy Activity with the First CD20-Targeted Immunotoxin, MT-3724, in Subjects with Relapsed/Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL)
Abstract Number: 4098
Presenter: Daniel Persky MD, University of Arizona Cancer Center
Session: 626. Aggressive Lymphoma (Diffuse Large B-Cell and Other Aggressive B-Cell Non-Hodgkin Lymphomas)—Results from Prospective Clinical Trials 
Time: Monday, December 9, 2019: 6:00 PM-8:00 PM ET

This is a multi-center, open-label, dose-escalation and dose-expansion study of MT-3724, the first CD20 targeted immunotoxin to enter clinical trials.  The Phase 1/1b portion of the study consists of two Parts in which a total of 27 subjects with NHL were enrolled; 21 in Part 1 (dose escalation) and 6 in Part 2 (expansion cohort), both closed to enrollment.  In total, 25 subjects were evaluable for efficacy, including 19 subjects with DLBCL or mixed DLBCL/follicular lymphoma.

MT-3724 competes for binding with rituximab (RTX) and other commercially available CD20-targeting monoclonal antibodies. Consistent with this competition, initial efficacy data from the dose expansion study revealed only one of eight subjects with measurable serum rituximab (RTX) levels had any suggestion of benefit (a mixed response) to MT-3724. 

The expansion cohort mandated negative serum RTX levels for enrolled subjects.  Of the 13 serum rituximab negative (RTX-neg) DLBCL or mixed DLBCL/FL subjects, 5 responded (38% objective response rate) across the range of 5 to 100 μg/kg doses. Of the 5 responses, 2 were complete responses (CRs) and 3 were partial responses (PRs).  Three patients had stable disease (including 2 patients with 49% and 47% tumor reductions) and 5 patients had progressive disease.

Of the 5 serum RTX-neg subjects with DLBCL who received MT-3724 at 50 μg/kg, the maximum tolerated dose (MTD), 3 responded (2 CR, 1 PRs).   Of all 25 subjects evaluable for efficacy, 13 developed anti-drug antibodies (ADAs) or neutralizing antibodies (NAbs); the development of ADAs or NAbs did not preclude benefit of MT-3724, consistent with what has been seen with other immunotoxins. Safety events were mostly mild to moderate, and dose limiting toxicities (DLTs) were indicative of innate immune response, including grade 2 capillary leak syndrome and grades 1-3 arthralgias and myalgias.   No life-threatening toxicities were attributed to MT-3724.

A Phase 2 dose-expansion portion of the study (Part 3) has been initiated to investigate MT-3724 in serum RTX-neg subjects with DLBCL. This is actively enrolling globally. A tolerable dose and schedule for the Phase 2 has been identified: 50 μg/kg/dose with a cap of 6000 μg/dose infused over 1 hour on Days 1, 3, 5, 8, 10 and 12 of a 21-day cycle. (ClinicalTrials.gov Identifier: NCT02361346).

Poster Title: A Phase 2a Open-Label Study to Investigate Safety and Tolerability (including the MTD), Efficacy, Pharmacokinetics, Pharmacodynamics and Immunogenicity of MT-3724 in Combination with Lenalidomide in Subjects with Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma
Presenter: Jason Tache, DO, BRCR Medical Center
Abstract #:  1597
Session: 626. Aggressive Lymphoma (Diffuse Large B-Cell and Other Aggressive B-Cell Non-Hodgkin Lymphomas)—Results from Prospective Clinical Trials
Time and Location: Saturday, December 7, 2019: 5:30 PM-7:30 PM ET

MT-3724. a novel Engineered Toxin Body (ETB), possesses specific and high affinity for CD20+ cells and causes apoptosis via a unique mechanism of action, forced internalization of the ETB bound to the receptor, retrograde transport through the cytosol, and enzymatic deactivation of ribosomal function.  Therefore, combining MT‑3724 with standard cytotoxic chemotherapy and/or immune modulatory agents may provide enhanced benefit in NHL treatment algorithms. This is a multi-center, open-label, multiple-dose Phase 2a study designed to evaluate MT-3724 in combination with lenalidomide in adult subjects with histologically confirmed, relapsed or refractory NHL.  The primary objective is to determine safety and tolerability, including the MTD, of MT-3724 + lenalidomide. Secondary objectives include pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity and tumor response.

The study will be conducted in two parts: Part 1 will include MT-3724 dose escalation according to the modified 3+3 design to identify the MTD of MT-3724 in combination with standard doses of lenalidomide and will include up to 24 subjects with histologically confirmed NHL. Part 2 is designed to confirm the safety and tolerability of MT-3724 + lenalidomide in the MTD Expansion Cohort, where the dose declared as MTD of MT-3724 in Part 1 would be given in combination with lenalidomide in up to 40 subjects with CD20+ DLBCL. In addition, the PK, PD, immunogenicity and tumor response of MT-3724 + lenalidomide will be evaluated in Part 2.

The study is currently ongoing; eligible subjects will be identified and treated through competitive enrollment at multiple study centers (ClinicalTrials.gov Identifier: NCT03645395).

Copies of the posters presented at ASH can be found in the Presentations section of Molecular Templates’ website at http://ir.mtem.com/events-and-presentations/presentations.

About Molecular Templates 
Molecular Templates is a clinical-stage oncology company focused on the discovery and development of differentiated, targeted, biologic therapeutics. We believe our proprietary biologic drug platform technology, referred to as engineered toxin bodies, or ETBs, provides a differentiated mechanism of action that may address some of the limitations associated with currently available cancer therapeutics. ETBs utilize a genetically engineered form of Shiga-like Toxin A subunit, or SLTA, a ribosome inactivating bacterial protein, that can be targeted to specifically destroy cancer cells.

Forward-Looking Statements
This press release contains forward-looking statements for purposes of the Private Securities Litigation Reform Act of 1995 (the “Act”). Molecular Templates disclaims any intent or obligation to update these forward-looking statements, and claims the protection of the Act’s Safe Harbor for forward-looking statements.  All statements, other than statements of historical facts, included in this press release regarding strategy, future operations, future financial position, future revenue, projected expenses, prospects, plans and objectives of management are forward-looking statements. In addition, when or if used in this press release, the words “may,” “could,” “should,” “anticipate,” “believe,” “estimate,” “expect,” “intend,” “plan,” “predict” and similar expressions and their variants, as they relate to Molecular Templates may identify forward-looking statements.  Examples of such statements include, but are not limited to, statements relating to the development of the Company’s lead program, MT-3724, and the replication of  monotherapy activity in the Phase II studies with MT-3724; the expected timing of submitting various IND applications, conducting studies, dosing patients, and reporting additional updates on studies or data from various studies; and the Company’s belief that its proprietary biologic drug platform technology, or ETBs, provides for a differentiated mechanism of action that may address some of the limitations associated with currently available cancer therapeutics.

Forward-looking statements are not guarantees of future performance and involve risks and uncertainties. Actual events or results may differ materially from those discussed in the forward-looking statements as a result of various factors including, but not limited to, the uncertainties inherent in the preclinical and clinical development process; whether the Company’s cash resources will be sufficient to fund its continuing operations for the periods and/or trials anticipated; the ability of the Company to protect its intellectual property rights; and legislative, regulatory, political and economic developments, as well as those risks identified under the heading “Risk Factors” in the Company’s filings with the SEC. Any forward-looking statements contained in this press release speak only as of the date hereof, and the Company specifically disclaims any obligation to update any forward-looking statement, whether because of new information, future events or otherwise.

Investor Contact:

Adam Cutler
Chief Financial Officer
adam.cutler@mtem.com
862-204-4006

Source: Molecular Templates, Inc.