Therapy Areas: Autoimmune
Xencor Enters Global Collaboration and License Agreement with Janssen to Advance Plamotamab and XmAb CD28 Bispecific Antibody Combinations for the Treatment of Patients With B-Cell Malignancies
5 October 2021 - - US-based clinical-stage biopharmaceutical company Xencor, Inc. (NASDAQ: XNCR) has forged an exclusive collaboration and worldwide license agreement with Johnson and Johnson's (NYSE: JNJ) Janssen Biotech Inc business to develop and commercialize plamotamab and novel XmAb B-cell targeting bispecific antibodies that are designed to conditionally activate T cells through the CD28 co-stimulatory receptor, the company said.

Plamotamab is a CD20 x CD3 XmAb bispecific antibody and is currently completing a Phase 1 dose-escalation study in patients with CD20-expressing hematologic malignancies.

Under the terms of the agreement, Janssen will receive worldwide exclusive development and commercialization rights to plamotamab, whether as a monotherapy or in combination regimens. Xencor will collaborate with Janssen on further clinical development of plamotamab with Janssen paying 80% and Xencor paying 20% of costs, including those for a subcutaneous formulation anticipated to enter clinical trials in 2022.

In parallel, Xencor will continue, at its own expense, a previously announced clinical collaboration to evaluate the combination of plamotamab, tafasitamab and lenalidomide in patients with B-cell lymphoma, including a Phase 2 trial in relapsed or refractory diffuse large B-cell lymphoma anticipated to start in late 2021 or early 2022.

Further, Xencor will apply its XmAb bispecific Fc technology to create and characterize XmAb CD28 bispecific antibody candidates against B-cell targets during a two-year joint research collaboration, and Janssen will have an exclusive worldwide license to develop selected molecules in combination with plamotamab and other agents, such as CD3 bispecific antibodies.

Xencor will receive an upfront payment of USD100 m, and Johnson and Johnson Innovation - JJDC, Inc. will purchase USD 25m of newly issued shares of Xencor common stock.

Xencor will be eligible to receive up to USD 1.188bn in potential development, regulatory and sales milestone payments, as well as tiered royalties on net sales of products developed under the agreement, ranging from mid-teen to low-twenties percentages for products containing plamotamab and plamotamab/CD28 bispecific antibody combinations.

Separate terms apply to CD28 bispecific antibodies commercialized outside of a plamotamab combination, where Xencor retains an option to co-fund development costs in exchange for higher royalties and the right to co-detail such products in the United States.

The agreement is subject to customary closing conditions, including clearance under the Hart-Scott-Rodino Antitrust Improvements Act, and closing is expected to occur in 4Q21.

Plamotamab is an investigational tumor-targeted XmAb bispecific antibody that contains both a CD20 binding domain and a cytotoxic T-cell binding domain. CD20 is highly expressed across a range of B-cell tumors, including non-Hodgkin lymphoma and chronic lymphocytic leukemia.

Engagement of CD3 by plamotamab activates T cells for highly potent and targeted killing of CD20-expressing tumor cells.

Plamotamab is currently being evaluated in a Phase 1 clinical study for the treatment of patients with CD20-expressing hematologic malignancies, including NHL and CLL.

Preliminary safety and anti-tumor activity from the Phase 1 study indicated that plamotamab was generally well tolerated and demonstrated encouraging clinical activity as a monotherapy.

CD28 bispecific antibodies are a class of T cell engager designed to synergize with and complement, in a tumor-specific manner, other mechanisms of T cell activation, such as checkpoint inhibitors and CD3 bispecific antibodies.

CD28 is a key immune co-stimulatory receptor on T cells that historically has proved difficult to engage therapeutically.

Xencor has engineered XmAb bispecific antibodies, targeting CD28 with one binding domain and tumor cells with a second binding domain, that have demonstrated tumor-dependent T-cell activity in preclinical testing.

Xencor announced its first collaboration with Janssen to discover a CD28 bispecific antibody against an undisclosed prostate tumor target in 2020.

Xencor's lead CD28 bispecific program, XmAb808, targets B7-H3 for potential use against a wide range of tumor types and is expected to start clinical development in 2022.

Xencor is a clinical-stage biopharmaceutical company developing engineered monoclonal antibodies and cytokines for the treatment of cancer and autoimmune diseases.

Currently, 22 candidates engineered with Xencor's XmAb technology are in clinical development internally and with partners. Xencor's XmAb antibody engineering technology enables small changes to the structure of proteins resulting in new mechanisms of therapeutic action.
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