antibodies Review Therapeutic Monoclonal Antibodies Targeting Immune Checkpoints for the Treatment of Solid Tumors 1, , 1, , 1 1 Nicholas Gravbrot * y , Kacy Gilbert-Gard * y, Paras Mehta , Yarah Ghotmi , Madhulika Banerjee 1, Christopher Mazis 1 and Srinath Sundararajan 1,2 1 Division of Hematology-Oncology, Department of Medicine, University of Arizona Cancer Center, Tucson, AZ 85724, USA;
[email protected] (P.M.);
[email protected] (Y.G.);
[email protected] (M.B.);
[email protected] (C.M.);
[email protected] (S.S.) 2 Texas Oncology, Dallas, TX 75251, USA * Correspondence:
[email protected] (N.G.);
[email protected] (K.G.-G.) N.G. and K.G.-G. contributed equally to this work. y Received: 24 September 2019; Accepted: 16 October 2019; Published: 21 October 2019 Abstract: Recently, modulation of immune checkpoints has risen to prominence as a means to treat a number of solid malignancies, given the durable response seen in many patients and improved side effect profile compared to conventional chemotherapeutic agents. Several classes of immune checkpoint modulators have been developed. Here, we review current monoclonal antibodies directed against immune checkpoints that are employed in practice today. We discuss the history, mechanism, indications, and clinical data for each class of therapies. Furthermore, we review the challenges to durable tumor responses that are seen in some patients and discuss possible interventions to circumvent these barriers. Keywords: immunotherapy; checkpoint inhibitor; monoclonal antibody; cancer therapy 1. Introduction In recent years, the limitations of conventional chemotherapy have spurred research into more precise cancer treatment, using targeted therapies in hopes of selectively eradicating cancer while sparing normal host cells.