Crystal Mackall, Postdoctoral Faculty Sponsor
Crystal Mackall, Postdoctoral Research Mentor
Enhanced T cell effector activity by targeting the Mediator kinase module.
Science (New York, N.Y.)
2022; 378 (6620): eabn5647
T cells are the major arm of the immune system responsible for controlling and regressing cancers. To identify genes limiting T cell function, we conducted genome-wide CRISPR knockout screens in human chimeric antigen receptor (CAR) T cells. Top hits were MED12 and CCNC, components of the Mediator kinase module. Targeted MED12 deletion enhanced antitumor activity and sustained the effector phenotype in CAR- and T cell receptor-engineered T cells, and inhibition of CDK8/19 kinase activity increased expansion of nonengineered T cells. MED12-deficient T cells manifested increased core Meditator chromatin occupancy at transcriptionally active enhancers-most notably for STAT and AP-1 transcription factors-and increased IL2RA expression and interleukin-2 sensitivity. These results implicate Mediator in T cell effector programming and identify the kinase module as a target for enhancing potency of antitumor T cell responses.
View details for DOI 10.1126/science.abn5647
View details for PubMedID 36356142
Enhanced safety and efficacy of protease-regulated CAR-T cell receptors.
Regulatable CAR platforms could circumvent toxicities associated with CAR-T therapy, but existing systems have shortcomings including leakiness and attenuated activity. Here, we present SNIP CARs, a protease-based platform for regulating CAR activity using an FDA-approved small molecule. Design iterations yielded CAR-T cells that manifest full functional capacity with drug and no leaky activity in the absence of drug. In numerous models, SNIP CAR-T cells were more potent than constitutive CAR-T cells and showed diminished T cell exhaustion and greater stemness. In a ROR1-based CAR lethality model, drug cessation following toxicity onset reversed toxicity, thereby credentialing the platform as a safety switch. In the same model, reduced drug dosing opened a therapeutic window that resulted in tumor eradication in the absence of toxicity. SNIP CARs enable remote tuning of CAR activity, which provides solutions to safety and efficacy barriers that are currently limiting progress in using CAR-T cells to treat solid tumors.
View details for DOI 10.1016/j.cell.2022.03.041
View details for PubMedID 35483375
Delivery of CAR-T cells in a transient injectable stimulatory hydrogel niche improves treatment of solid tumors.
2022; 8 (14): eabn8264
Adoptive cell therapy (ACT) has proven to be highly effective in treating blood cancers, but traditional approaches to ACT are poorly effective in treating solid tumors observed clinically. Novel delivery methods for therapeutic cells have shown promise for treatment of solid tumors when compared with standard intravenous administration methods, but the few reported approaches leverage biomaterials that are complex to manufacture and have primarily demonstrated applicability following tumor resection or in immune-privileged tissues. Here, we engineer simple-to-implement injectable hydrogels for the controlled co-delivery of CAR-T cells and stimulatory cytokines that improve treatment of solid tumors. The unique architecture of this material simultaneously inhibits passive diffusion of entrapped cytokines and permits active motility of entrapped cells to enable long-term retention, viability, and activation of CAR-T cells. The generation of a transient inflammatory niche following administration affords sustained exposure of CAR-T cells, induces a tumor-reactive CAR-T phenotype, and improves efficacy of treatment.
View details for DOI 10.1126/sciadv.abn8264
View details for PubMedID 35394838
GPC2-CAR T cells tuned for low antigen density mediate potent activity against neuroblastoma without toxicity
2022; 40 (1): 53-+
View details for DOI 10.1016/j.ccell.2021.12-005
View details for Web of Science ID 000744691500012
Transient rest restores functionality in exhausted CAR-T cells through epigenetic remodeling.
Science (New York, N.Y.)
2021; 372 (6537)
T cell exhaustion limits immune responses against cancer and is a major cause of resistance to chimeric antigen receptor (CAR)-T cell therapeutics. Using murine xenograft models and an in vitro model wherein tonic CAR signaling induces hallmark features of exhaustion, we tested the effect of transient cessation of receptor signaling, or rest, on the development and maintenance of exhaustion. Induction of rest through enforced down-regulation of the CAR protein using a drug-regulatable system or treatment with the multikinase inhibitor dasatinib resulted in the acquisition of a memory-like phenotype, global transcriptional and epigenetic reprogramming, and restored antitumor functionality in exhausted CAR-T cells. This work demonstrates that rest can enhance CAR-T cell efficacy by preventing or reversing exhaustion, and it challenges the notion that exhaustion is an epigenetically fixed state.
View details for DOI 10.1126/science.aba1786
View details for PubMedID 33795428
Global analysis of shared T cell specificities in human non-small cell lung cancer enables HLA inference and antigen discovery.
2021; 54 (3): 586–602.e8
To identify disease-relevant T cell receptors (TCRs) with shared antigen specificity, we analyzed 778,938 TCRβ chain sequences from 178 non-small cell lung cancer patients using the GLIPH2 (grouping of lymphocyte interactions with paratope hotspots 2) algorithm. We identified over 66,000 shared specificity groups, of which 435 were clonally expanded and enriched in tumors compared to adjacent lung. The antigenic epitopes of one such tumor-enriched specificity group were identified using a yeast peptide-HLA A∗02:01 display library. These included a peptide from the epithelial protein TMEM161A, which is overexpressed in tumors and cross-reactive epitopes from Epstein-Barr virus and E. coli. Our findings suggest that this cross-reactivity may underlie the presence of virus-specific T cells in tumor infiltrates and that pathogen cross-reactivity may be a feature of multiple cancers. The approach and analytical pipelines generated in this work, as well as the specificity groups defined here, present a resource for understanding the T cell response in cancer.
View details for DOI 10.1016/j.immuni.2021.02.014
View details for PubMedID 33691136
PET reporter gene imaging and ganciclovir-mediated ablation of chimeric antigen receptor T-cells in solid tumors.
Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. Additionally, the potential adverse effects of CAR T-cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a positron emission tomography (PET) reporter gene for imaging of T-cell trafficking in brain tumor patients. The HSV1-TK enzyme can act as a suicide gene of transduced cells through treatment with the prodrug ganciclovir (GCV). Here we report the molecular engineering, imaging, and GCV-mediated destruction of B7H3 CAR T-cells incorporating a mutated version of the HSV1-tk gene (sr39tk) with improved enzymatic activity for GCV. The sr39tk gene did not affect B7H3 CAR T-cell functionality and in vitro and in vivo studies in osteosarcoma models showed no significant effect on B7H3 CAR T-cell antitumor activity. PET/CT imaging with 9-(4-[18F]-fluoro-3-[hydroxymethyl]butyl)guanine [18F]FHBG of B7H3-sr39tk CAR T-cells in an orthotopic model of osteosarcoma revealed tumor homing and systemic immune expansion. Bioluminescence and PET imaging of B7H3-sr39tk CAR T-cells confirmed complete tumor ablation with intraperitoneal GCV administration. This imaging and suicide ablation system can provide insight into CAR T-cell migration and proliferation during clinical trials while serving as a suicide switch to limit potential toxicities.
View details for DOI 10.1158/0008-5472.CAN-19-3579
View details for PubMedID 32958548