Check and Checkmate: Battling Cancer with Multiplex Immunotherapy
Authors: John C. Bell
Journal: Molecular Therapy (2020)

Immunotherapy is an exciting and potentially “game changing” approach to the treatment of cancer but, to date, is effective in only a minority of cancer patients. It is widely recognized that tumor plasticity and heterogeneity within and between cancer patients prevents any one modality from having significant activity in a broad spectrum of patients. Chen and Mellman1Chen D.S. Mellman I. Elements of cancer immunity and the cancer-immune set point.Nature. 2017; 541: 321-330Crossref PubMed Scopus (2565) Google Scholar have argued that each patient’s tumor has a cancer-immune setpoint that “represents the threshold that must be surpassed for a person with cancer to respond to immunotherapy”. Essentially, multiple dynamic hurdles in the hostile tumor microenvironment (TME) must be overcome in order to have an effective therapeutic regimen. In this issue of Molecular Therapy, Porter et al.2Porter C.E. Shaw A.R. Jung Y. Yip T. Castro P.D. Sandulache V.C. Sikora A. Gottschalk S. Ittman M.M. Brenner M.K. Suzuki M. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.Mol Ther. 2020; 28 (this issue): 1251-1262Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar describe a combinatorial immunotherapeutic approach designed to attack critical elements of the cancer immunity cycle that are thought to be necessary to overcome cancer immune setpoints. Their strategy attacks the cancer on multiple fronts using a unique virus vector system that combines an oncolytic virus with a “tag-along” gene therapy vehicle and a chimeric antigen receptor (CAR) T cell product. A successful immunotherapeutic strategy for cancer will be one that elicits a broad and robust repertoire of tumor-specific memory CD8+ and CD4+ cells, resulting in cancer cell killing and prevention of recurrence.3Chen D.S. Mellman I. Oncology meets immunology: the cancer-immunity cycle.Immunity. 2013; 39: 1-10Abstract Full Text Full Text PDF PubMed Scopus (3570) Google Scholar However, cancers evolve multiple strategies to prevent this from happening. They express factors that inactivate or block the recruitment of tumor-specific T cells; suppress the activity of innate immune cells; neutralize the activity of antigen processing and presenting cells; downregulate the expression of major histocompatibility complex (MHC) expressing molecules; and recruit and promote the survival of immune-suppressing cell types. Broadly speaking, tumors have been classified as inflamed, immune excluded, and immune desert based upon histological characterization of the extent and geography of immune cell infiltrates found within them. In general, inflamed tumors have a lower so-called “cancer-immune setpoint” and respond better to immune checkpoint inhibitor (ICI) therapy. Checkpoint proteins, such as PD-L1 on tumor cells and PD-1 on T cells, help keep immune responses in check. Blocking the binding of PD-L1 to PD-1 with an immune checkpoint inhibitor (anti-PD-L1 or anti-PD-1) enables T cells to kill tumor cells. The immune excluded and immune desert phenotypes have a higher setpoint and do not respond to ICI or other forms of immunotherapy. A goal of novel immunotherapeutic strategies is to lower the cancer-immune setpoint, although, based upon the dynamic nature and complexity of a hostile TME, this will not be achieved with a single targeted therapeutic agent. Porter et al.2Porter C.E. Shaw A.R. Jung Y. Yip T. Castro P.D. Sandulache V.C. Sikora A. Gottschalk S. Ittman M.M. Brenner M.K. Suzuki M. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.Mol Ther. 2020; 28 (this issue): 1251-1262Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar tackled this problem using an orchestrated therapeutic approach to overcome some of the well understood hurdles that mitigate successful immunotherapy. Oncolytic viruses (OVs) are designed to selectively infect and destroy cancer cells, releasing antigens that are subsequently presented to the immune system and generating a targeted T cell response against the tumor.4Fu L.Q. Wang S.B. Cai M.H. Wang X.J. Chen J.Y. Tong X.M. Chen X.Y. Mou X.Z. Recent advances in oncolytic virus-based cancer therapy.Virus Res. 2019; 270: 197675Crossref PubMed Scopus (24) Google Scholar In addition, the act of infection can initiate an inflammatory signal, triggering the recruitment of T cells and other immune effector cells into the TME. In general, however, oncolytic activity on its own is insufficient to produce significant and long-lasting responses in cancer patients,5Streby K.A. Currier M.A. Triplet M. Ott K. Dishman D.J. Vaughan M.R. Ranalli M.A. Setty B. Skeens M.A. Whiteside S. et al.First-in-Human Intravenous Seprehvir in Young Cancer Patients: A Phase 1 Clinical Trial.Mol Ther. 2019; 27: 1930-1938Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar,6Hirooka Y. Kasuya H. Ishikawa T. Kawashima H. Ohno E. Villalobos I.B. Naoe Y. Ichinose T. Koyama N. Tanaka M. et al.A Phase I clinical trial of EUS-guided intratumoral injection of the oncolytic virus, HF10 for unresectable locally advanced pancreatic cancer.BMC Cancer. 2018; 18: 596Crossref PubMed Scopus (70) Google Scholar and considerable effort has gone into creating novel OV platforms that lyse tumors while, at the same time, providing additional immune stimulating signals to the TME.7Twumasi-Boateng K. Pettigrew J.L. Kwok Y.Y.E. Bell J.C. Nelson B.H. Oncolytic viruses as engineering platforms for combination immunotherapy.Nat. Rev. Cancer. 2018; 18: 419-432Crossref PubMed Scopus (225) Google Scholar Several groups have developed highly selective oncolytic adenovirus; however, a significant limitation of this platform is the constrained size of therapeutic payload that can be incorporated into the vector without compromising replication and oncolytic activity. To overcome this issue, Porter et al.2Porter C.E. Shaw A.R. Jung Y. Yip T. Castro P.D. Sandulache V.C. Sikora A. Gottschalk S. Ittman M.M. Brenner M.K. Suzuki M. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.Mol Ther. 2020; 28 (this issue): 1251-1262Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar developed a two-virus system comprised of a “gutted adenovirus genome” or helper dependent adenovirus (HDAd) that can be complemented by a replication-competent oncolytic adenovirus (Onc.Ad).8Farzad L. Cerullo V. Yagyu S. Bertin T. Hemminki A. Rooney C. Lee B. Suzuki M. Combinatorial treatment with oncolytic adenovirus and helper-dependent adenovirus augments adenoviral cancer gene therapy.Mol. Ther. Oncolytics. 2014; 1: 14008Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar,9Farzad L.M. Suzuki M. Feasibility of Applying Helper-Dependent Adenoviral Vectors for Cancer Immunotherapy.Biomedicines. 2014; 2: 110-131Crossref PubMed Scopus (3) Google Scholar In their strategy, a cancer gene therapy vector was engineered by removing all viral coding genes from an adenovirus backbone, creating a replication-incompetent virus that can be armed with approximately 34 kb of therapeutic transgenes. Their HDAd was engineered to express immune stimulating genes that attack different barriers commonly found in tumors. In earlier studies, the authors created an HDAd expressing a PD-L1 blocking antibody to overcome immune checkpoint inhibition mediated by the PD1/PDL1 axis. A second transgene, the pro-inflammatory cytokine interleukin (IL)-12p70, was added to create a dually armed vector called HDAdDuo. IL-12 is known to potentiate the activity of anti-PD1 therapy and, together, was shown to augment the activity of a CAR T cell product directed against the HER2 antigen in solid tumor models.10Rosewell Shaw A. Porter C.E. Watanabe N. Tanoue K. Sikora A. Gottschalk S. Brenner M.K. Suzuki M. Adenovirotherapy Delivering Cytokine and Checkpoint Inhibitor Augments CAR T Cells against Metastatic Head and Neck Cancer.Mol Ther. 2017; 25: 2440-2451Abstract Full Text Full Text PDF PubMed Scopus (114) Google Scholar, 11Rosewell Shaw A. Suzuki M. Recent advances in oncolytic adenovirus therapies for cancer.Curr. Opin. Virol. 2016; 21: 9-15Crossref PubMed Scopus (71) Google Scholar, 12Rosewell Shaw A. Suzuki M. Oncolytic Viruses Partner With T-Cell Therapy for Solid Tumor Treatment.Front. Immunol. 2018; 9: 2103Crossref PubMed Scopus (38) Google Scholar CAR T therapy often fails due to the selection of tumor cells that have lost the expression of the antigen targeted by the engineered T cell product.13Bukhari A. El Chaer F. Koka R. Singh Z. Hutnick E. Ruehle K. Lee S.T. Kocoglu M.H. Shanholtz C. Badros A. et al.Rapid relapse of large B-cell lymphoma after CD19 directed CAR-T-cell therapy due to CD-19 antigen loss.Am. J. Hematol. 2019; 94: E273-E275Crossref PubMed Scopus (22) Google Scholar, 14Orlando E.J. Han X. Tribouley C. Wood P.A. Leary R.J. Riester M. Levine J.E. Qayed M. Grupp S.A. Boyer M. et al.Genetic mechanisms of target antigen loss in CAR19 therapy of acute lymphoblastic leukemia.Nat. Med. 2018; 24: 1504-1506Crossref PubMed Scopus (277) Google Scholar, 15O’Rourke D.M. Nasrallah M.P. Desai A. Melenhorst J.J. Mansfield K. Morrissette J.J.D. Martinez-Lage M. Brem S. Maloney E. Shen A. et al.A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma.Sci. Transl. Med. 2017; 9: eaaa0984Crossref PubMed Scopus (883) Google Scholar Porter et al.2Porter C.E. Shaw A.R. Jung Y. Yip T. Castro P.D. Sandulache V.C. Sikora A. Gottschalk S. Ittman M.M. Brenner M.K. Suzuki M. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.Mol Ther. 2020; 28 (this issue): 1251-1262Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar created an HDAdTrio vector that additionally expressed a T cell engager or bispecific tumor-targeted T cell engager (BiTE) directed against CD44v6, an antigen demonstrated to be widely overexpressed on a number of cancer cell types. The BiTE, when expressed from HDAdTrio, is able to arm HER2.CAR T cells and facilitate the killing of CD44v6-expressing cells, whether they express HER2 or not, and thus, in principle, helps to minimize the CAR T therapy failure due to antigen loss. As predicted, the addition of a replication-competent adenovirus or Onc.Ad amplified the expression of HDAdTrio transgenes within the TME and created a significantly more effective therapeutic regimen in orthotopic tumor models. The experiments described by Porter et al.2Porter C.E. Shaw A.R. Jung Y. Yip T. Castro P.D. Sandulache V.C. Sikora A. Gottschalk S. Ittman M.M. Brenner M.K. Suzuki M. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous Tumors.Mol Ther. 2020; 28 (this issue): 1251-1262Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar could represent an important step forward in the development of CAR T cell treatments for solid tumors. While a pro-inflammatory TME triggered by OV activity was predicted to aid in the recruitment and activation of CAR T cells in solid tumors,16Ajina A. Maher J. Synergistic combination of oncolytic virotherapy with CAR T-cell therapy.Prog. Mol. Biol. Transl. Sci. 2019; 164: 217-292Crossref PubMed Scopus (11) Google Scholar they showed that, depending upon the complexity of the tumor under attack, a more sophisticated multi-targeted pronged approach may be required. This concept is now well appreciated, and several OV therapeutics that encode multiple therapeutic transgenes are under clinical development. One potential advantage of the Onc.Ad/HDAdTrio approach is that the expression of therapeutic transgenes is uncoupled from oncolytic activity. This may permit more persistent expression of therapeutic transgenes in tumor cells transduced by HDAdTrio and not infected and killed off by the Onc.Ad. On the other hand, clinically advancing a therapeutic that involves a combination of vectors may have significant regulatory hurdles. In either case, these studies highlight the need for sophisticated strategies in the game of chess between our dynamic immune systems and malignancies that strive to evade or blunt anti-tumor immune responses. Oncolytic Adenovirus Armed with BiTE, Cytokine, and Checkpoint Inhibitor Enables CAR T Cells to Control the Growth of Heterogeneous TumorsPorter et al.Molecular TherapyFebruary 24, 2020In BriefTo enable HER2.CAR T cells to target two tumor antigens through both CAR and native TCR, Porter et al. developed a binary oncolytic-helper adenovirus expressing an engager molecule (BiTE), IL-12, and PD-L1 antibody. This combination therapy significantly improved tumor control and survival in models of HER2-positive and HER-negative cancer. Full-Text PDF Open Archive