Tumor Regression Following Engineered Polyomavirus-Specific T Cell Therapy in Immune Checkpoint Inhibitor-Refractory Merkel Cell Carcinoma.

Although immune check-point inhibitors (CPIs) revolutionized treatment of Merkel cell carcinoma (MCC), patients with CPI-refractory MCC lack effective therapy. More than 80% of MCC express T-antigens encoded by Merkel cell polyomavirus, which is an ideal target for T-cell receptor (TCR)-based immunotherapy. However, MCC often repress HLA expression, requiring additional strategies to reverse the downregulation for allowing T cells to recognize their targets.

qPCR assay for detection of Woodchuck Hepatitis Virus Post-Transcriptional Regulatory Elements from CAR-T and TCR-T cells in fresh and formalin-fixed tissue.

As adoptive cellular therapies become more commonplace in cancer care, there is a growing need to monitor site-specific localization of engineered cells-such as chimeric antigen receptor T (CAR-T) cells and T-cell receptor T (TCR-T) cells-in patients' tissues to understand treatment effectiveness as well as associated adverse events. Manufacturing CAR-T and TCR-T cells involves transduction with viral vectors commonly containing the WPRE gene sequence to enhance gene expression, providing a viable assay target unique to these engineered cells. Quantitative PCR (qPCR) is currently used clinically in fresh patient tissue samples and blood with target sequences specific to each immunotherapy product.

MR1-restricted T cell clonotypes are associated with "resistance" to Mycobacterium tuberculosis infection.

T cells are required for protective immunity against Mycobacterium tuberculosis. We recently described a cohort of Ugandan household contacts of tuberculosis cases who appear to "resist" M. tuberculosis infection (resisters; RSTRs) and showed that these individuals harbor IFN-γ-independent T cell responses to M.

HA-1-targeted T-cell receptor T-cell therapy for recurrent leukemia after hematopoietic stem cell transplantation.

Relapse is the leading cause of death after allogeneic hematopoietic stem cell transplantation (HCT) for leukemia. T cells engineered by gene transfer to express T cell receptors (TCR; TCR-T) specific for hematopoietic-restricted minor histocompatibility (H) antigens may provide a potent selective antileukemic effect post-HCT. We conducted a phase 1 clinical trial using a novel TCR-T product targeting the minor H antigen, HA-1, to treat or consolidate treatment of persistent or recurrent leukemia and myeloid neoplasms.

Expansion of the HSV-2-specific T cell repertoire in skin after immunotherapeutic HSV-2 vaccine.

The skin at the site of HSV-2 reactivation is enriched for HSV-2-specific T cells. To evaluate whether an immunotherapeutic vaccine could elicit skin-based memory T cells, we studied skin biopsies and HSV-2-reactive CD4 T cells from peripheral blood mononuclear cells (PBMCs) by T cell receptor β () sequencing before and after vaccination with a replication-incompetent whole virus HSV-2 vaccine candidate (HSV529). The representation of HSV-2-reactive CD4 sequences from PBMCs in the skin repertoire increased after the first vaccine dose.

Circulating cancer-specific CD8 T cell frequency is associated with response to PD-1 blockade in Merkel cell carcinoma.

Understanding cancer immunobiology has been hampered by difficulty identifying cancer-specific T cells. Merkel cell polyomavirus (MCPyV) causes most Merkel cell carcinomas (MCCs). All patients with virus-driven MCC express MCPyV oncoproteins, facilitating identification of virus (cancer)-specific T cells.

Enhancing immunogenic responses through CDK4/6 and HIF2α inhibition in Merkel cell carcinoma.

Approximately 50% of Merkel cell carcinoma (MCC) patients facing this highly aggressive skin cancer initially respond positively to PD-1-based immunotherapy. Nevertheless, the recurrence of MCC post-immunotherapy emphasizes the pressing need for more effective treatments. Recent research has highlighted Cyclin-dependent kinases 4 and 6 (CDK4/6) as pivotal cell cycle regulators gaining prominence in cancer studies.

Repeated mRNA vaccination sequentially boosts SARS-CoV-2-specific CD8 T cells in persons with previous COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hybrid immunity is more protective than vaccination or previous infection alone. To investigate the kinetics of spike-reactive T (T) cells from SARS-CoV-2 infection through messenger RNA vaccination in persons with hybrid immunity, we identified the T cell receptor (TCR) sequences of thousands of index T cells and tracked their frequency in bulk TCRβ repertoires sampled longitudinally from the peripheral blood of persons who had recovered from coronavirus disease 2019 (COVID-19). Vaccinations led to large expansions in memory T cell clonotypes, most of which were CD8 T cells, while also eliciting diverse T cell clonotypes not observed before vaccination.

Timing of anti-PD-L1 antibody initiation affects efficacy/toxicity of CD19 CAR T-cell therapy for large B-cell lymphoma.

More than half of the patients treated with CD19-targeted chimeric antigen receptor (CAR) T-cell immunotherapy for large B-cell lymphoma (LBCL) do not achieve durable remission, which may be partly due to PD-1/PD-L1-associated CAR T-cell dysfunction. We report data from a phase 1 clinical trial (NCT02706405), in which adults with LBCL were treated with autologous CD19 CAR T cells (JCAR014) combined with escalating doses of the anti-PD-L1 monoclonal antibody, durvalumab, starting either before or after CAR T-cell infusion. The addition of durvalumab to JCAR014 was safe and not associated with increased autoimmune or immune effector cell-associated toxicities.

Factors associated with long-term outcomes of CD19 CAR T-cell therapy for relapsed/refractory CLL.

High response rates have been reported after CD19-targeted chimeric antigen receptor-modified (CD19 CAR) T-cell therapy for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL), yet the factors associated with duration of response in this setting are poorly characterized. We analyzed long-term outcomes in 47 patients with R/R CLL and/or Richter transformation treated on our phase 1/2 clinical trial of CD19 CAR T-cell therapy with an updated median follow-up of 79.6 months.

Genome Editing in Engineered T Cells for Cancer Immunotherapy.

Advanced gene transfer technologies and profound immunological insights have enabled substantial increases in the efficacy of anticancer adoptive cellular therapy (ACT). In recent years, the U.S.

CD8 T cell clonotypes from prior SARS-CoV-2 infection predominate during the cellular immune response to mRNA vaccination.

Almost three years into the SARS-CoV-2 pandemic, hybrid immunity is highly prevalent worldwide and more protective than vaccination or prior infection alone. Given emerging resistance of variant strains to neutralizing antibodies (nAb), it is likely that T cells contribute to this protection. To understand how sequential SARS-CoV-2 infection and mRNA-vectored SARS-CoV-2 spike (S) vaccines affect T cell clonotype-level expansion kinetics, we identified and cross-referenced TCR sequences from thousands of S-reactive single cells against deeply sequenced peripheral blood TCR repertoires longitudinally collected from persons during COVID-19 convalescence through booster vaccination.

An In Vivo Model of Human Macrophages in Metastatic Melanoma.

Despite recent therapeutic progress, advanced melanoma remains lethal for many patients. The composition of the immune tumor microenvironment (TME) has decisive impacts on therapy response and disease outcome, and high-dimensional analyses of patient samples reveal the heterogeneity of the immune TME. Macrophages infiltrate TMEs and generally associate with tumor progression, but the underlying mechanisms are incompletely understood.

Targeting an alternate Wilms' tumor antigen 1 peptide bypasses immunoproteasome dependency.

Designing effective antileukemic immunotherapy will require understanding mechanisms underlying tumor control or resistance. Here, we report a mechanism of escape from immunologic targeting in an acute myeloid leukemia (AML) patient, who relapsed 1 year after immunotherapy with engineered T cells expressing a human leukocyte antigen A*02 (HLA-A2)-restricted T cell receptor (TCR) specific for a Wilms' tumor antigen 1 epitope, WT1 (T). Resistance occurred despite persistence of functional therapeutic T cells and continuous expression of WT1 and HLA-A2 by the patient's AML cells.

Shared inflammatory pathways and therapeutic strategies in COVID-19 and cancer immunotherapy.

COVID-19, the syndrome caused by the infection with SARS-CoV-2 coronavirus, is characterized, in its severe form, by interstitial diffuse pneumonitis and acute respiratory distress syndrome (ARDS). ARDS and systemic manifestations of COVID-19 are mainly due to an exaggerated immune response triggered by the viral infection. Cytokine release syndrome (CRS), an inflammatory syndrome characterized by elevated levels of circulating cytokines, and endothelial dysfunction are systemic manifestations of COVID-19.

Quality Is King: Fundamental Insights into Tumor Antigenicity from Virus-Associated Merkel Cell Carcinoma.

Merkel cell carcinoma (MCC) is a rare skin malignancy that is a paradigm cancer for solid tumor immunotherapy. MCCs associated with Merkel cell polyomavirus (virus-positive MCC [VP-MCC]) or chronic UV exposure (virus-negative MCC [VN-MCC]) are anti-PD(L)1 responsive, despite VP-MCC's low mutational burden. This suggests that antigen quality, not merely mutation quantity, dictates immunotherapy responsiveness, and cell-based therapies targeting optimal antigens may be effective.

Detection of engineered T cells in FFPE tissue by multiplex in situ hybridization and immunohistochemistry.

Identifying engineered T cells in situ is important to understand the location, persistence, and phenotype of these cells in patients after adoptive T cell therapy. While engineered cells are routinely characterized in fresh tissue or blood from patients by flow cytometry, it is difficult to distinguish them from endogenous cells in formalin-fixed, paraffin-embedded (FFPE) tissue biopsies. To overcome this limitation, we have developed a method for characterizing engineered T cells in fixed tissue using in situ hybridization (ISH) to the woodchuck hepatitis post-transcriptional regulatory element (WPRE) common in many lentiviral vectors used to transduce chimeric antigen receptor T (CAR-T) and T cell receptor T (TCR-T) cells, coupled with alternative permeabilization conditions that allows subsequent multiplex immunohistochemical (mIHC) staining within the same image.

The Anticancer Potential of T Cell Receptor-Engineered T Cells.

Adoptively transferred T cell receptor (TCR)-transgenic T cells (TCR-T cells) are not restricted by cell surface expression of their targets and are therefore poised to become a main pillar of cellular cancer immunotherapies. Addressing clinical and laboratory data, we discuss emerging features for the efficient deployment of novel TCR-T therapies, such as selection of ideal TCRs targeting validated epitopes with well-characterized cancer cell expression and processing, enhancing TCR-T effector function, trafficking, expansion, persistence, and memory formation by strategic selection of substrate cells, and gene-engineering with synthetic co-stimulatory circuits. Overall, a better understanding of the relevant mechanisms of action and resistance will help prioritize the vast array of potential TCR-T optimizations for future clinical products.

Prevalent and Diverse Intratumoral Oncoprotein-Specific CD8 T Cells within Polyomavirus-Driven Merkel Cell Carcinomas.

Merkel cell carcinoma (MCC) is often caused by persistent expression of Merkel cell polyomavirus (MCPyV) T-antigen (T-Ag). These non-self proteins comprise about 400 amino acids (AA). Clinical responses to immune checkpoint inhibitors, seen in about half of patients, may relate to T-Ag-specific T cells.

Age-Specific Incidence of Melanoma in the United States.

Importance: Melanoma is epidemiologically linked to UV exposure, particularly childhood sunburn. Public health campaigns are increasing sun-protective behavior in the United States, but the effect on melanoma incidence is unknown.

Objective: To examine the incidence of melanoma in the United States and whether any age-specific differences are present.