• Christina L Zuch de Zafra, Flordeliza Fajardo, Wendy Zhong, Matthew J Bernett, Umesh S Muchhal, Gregory L Moore, Jennitte Stevens, Ryan Case, Joshua T Pearson, Siyuan Liu, Patricia L McElroy, Jude Canon, John R Desjarlais, Angela Coxon, Mercedesz Balazs, and Olivier Nolan-Stevaux.
• Comparative Biology and Safety Sciences, Amgen South San Francisco, California.
• Clin Cancer Res. 2019 Jul 1; 25 (13): 3921-3933.

PurposeDespite advances in the treatment of multiple myeloma, new therapies are needed to induce more profound clinical responses. T-cell-redirected lysis triggered by bispecific antibodies recruiting T cells to cancer cells is a clinically validated mechanism of action against hematologic malignancies and CD38 is a tumor-associated antigen with near-universal expression in multiple myeloma. Thus, an anti-CD38/CD3 bispecific T-cell-recruiting antibody has the potential to be an effective new therapeutic for multiple myeloma.Experimental DesignAnti-CD38/CD3 XmAb T-cell-recruiting antibodies with different affinities for CD38 and CD3 were assessed in vitro and in vivo for their redirected T-cell lysis activity against cancer cell lines, their lower levels of cytokine release, and their potency in the presence of high levels of soluble CD38. Select candidates were further tested in cynomolgus monkeys for B-cell depletion and cytokine release properties.ResultsAMG 424 was selected on the basis of its ability to kill cancer cells expressing high and low levels of CD38 in vitro and trigger T-cell proliferation, but with attenuated cytokine release. In vivo, AMG 424 induces tumor growth inhibition in bone marrow-invasive mouse cancer models and the depletion of peripheral B cells in cynomolgus monkeys, without triggering excessive cytokine release. The activity of AMG 424 against normal immune cells expressing CD38 is also presented.ConclusionsThese findings support the clinical development of AMG 424, an affinity-optimized T-cell-recruiting antibody with the potential to elicit significant clinical activity in patients with multiple myeloma.©2019 American Association for Cancer Research.

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