Programmed death receptor-1/programmed death receptor ligand-1 blockade after transient lymphodepletion to treat myeloma.

Early phase clinical trials targeting the programmed death receptor-1/ligand-1 (PD-1/PD-L1) pathway to overcome tumor-mediated immunosuppression have reported promising results for a variety of cancers. This pathway appears to play an important role in the failure of immune reactivity to malignant plasma cells in multiple myeloma patients, as the tumor cells express relatively high levels of PD-L1, and T cells show increased PD-1 expression. In the current study, we demonstrate that PD-1/PD-L1 blockade with a PD-L1-specific Ab elicits rejection of a murine myeloma when combined with lymphodepleting irradiation. This particular combined approach by itself has not previously been shown to be efficacious in other tumor models. The antitumor effect of lymphodepletion/anti-PD-L1 therapy was most robust when tumor Ag-experienced T cells were present either through cell transfer or survival after nonmyeloablative irradiation. In vivo depletion of CD4 or CD8 T cells completely eliminated antitumor efficacy of the lymphodepletion/anti-PD-L1 therapy, indicating that both T cell subsets are necessary for tumor rejection. Elimination of myeloma by T cells occurs relatively quickly as tumor cells in the bone marrow were nearly nondetectable by 5 d after the first anti-PD-L1 treatment, suggesting that antimyeloma reactivity is primarily mediated by preactivated T cells, rather than newly generated myeloma-reactive T cells. Anti-PD-L1 plus lymphodepletion failed to improve survival in two solid tumor models, but demonstrated significant efficacy in two hematologic malignancy models. In summary, our results support the clinical testing of lymphodepletion and PD-1/PD-L1 blockade as a novel approach for improving the survival of patients with multiple myeloma.

Tumor-specific T cells in head and neck cancer have rescuable functionality and can be identified through single-cell co-culture.

BACKGROUND: Human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) remains a treatment-resistance disease with limited response to immunotherapy. While T cells in HNSCC are known to display phenotypic dysfunction, whether they retain rescuable functional capacity and tumor-killing capability remains unclear. METHODS: To investigate the functionality and tumor-specificity of tumor-infiltrating lymphocytes (TILs) across HNSCCs, malignant cell lines and TILs were derived from 31 HPV-negative HNSCCs at the time of standard surgical resection. T cell functional capacity was evaluated through ex vivo expansion, immunophenotyping, and IsoLight single-cell proteomics. Tumor-specificity was investigated through both bulk and single-cell tumor-TIL co-culture. RESULTS: TILs could be successfully generated from 24 patients (77%), including both previously untreated and radiation recurrent HNSCCs. We demonstrate that across HNSCCs, TILs express multiple exhaustion markers but maintain a predominantly effector memory phenotype. After ex vivo expansion, TILs retain immunogenic functionality even from radiation-resistant, exhausted, and T cell-depleted disease. We further demonstrate tumor-specificity of T cells across HNSCC patients through patient-matched malignant cell-T cell co-culture. Finally, we use optofluidic technology to establish an autologous single tumor cell-single T cell co-culture platform for HNSCC. Cells derived from three HNSCC patients underwent single-cell co-culture which enabled identification and visualization of individual tumor-killing TILs in real-time in all patients. CONCLUSIONS: These studies show that cancer-specific T cells exist across HNSCC patients with rescuable immunogenicity and can be identified on a single-cell level. These data lay the foundation for development of patient-specific T cell immunotherapies in HNSCC.

Phosphatidylethanolamine is externalized at the surface of microparticles.

Microparticles (MPs) are membrane-bound vesicles shed normally or as a result of various (pathological) stimuli. MPs contain a wealth of bio-active macromolecules. Aminophospholipid phosphatidylserine (PS) is present on the surface of many MPs. As PS and phosphatidylethanolamine (PE) are related, yet distinct aminophospholipids, the purpose of this study was to systematically and directly assess PE exposure on MPs. We examined MPs from various human cellular sources (human breast cancer, endothelial, red and white blood cells) by flow cytometry using a PE-specific probe, duramycin, and two PS-specific probes, annexin V and lactadherin. PS and PE exposure percentage was comparable on vascular and blood cell-derived MPs (80-90% of MP-gated events). However, the percentage of malignant breast cancer MPs exposing PE (~90%) was significantly higher than PS (~50%). Thus, while PS and PE exposure can result from a general loss of membrane asymmetry, there may also be distinct mechanisms of PE and PS exposure on MPs that vary by cellular source.

Controlling Cytokine Release Syndrome to Harness the Full Potential of CAR-Based Cellular Therapy.

Chimeric Antigen Receptor (CAR)-based therapies offer a promising, targeted approach to effectively treat relapsed or refractory B cell malignancies. However, the treatment-related toxicity defined as cytokine-release syndrome (CRS) often develops in patients, and if uncontrolled, can be fatal. Grading systems have now been developed to further characterize and objectify clinical findings in order to provide algorithm-based guidance on CRS-related treatment decisions. The pharmacological treatments associated with these algorithms suppress inflammation through a variety of mechanisms and are paramount to improving the safety profile of CAR-based therapies. However, fatalities are still occurring, and there are downsides to these treatments, including the possibility of disrupting CAR-T cell persistence. This review article will describe the clinical presentation and current management of CRS, and through our now deeper understanding of downstream signaling pathways, will provide a molecular framework to formulate new hypotheses regarding clinical applications to contain proinflammatory cytokines responsible for CRS.

Methods for studying voltage-gated sodium channels in heterologous expression systems.

The discovery that oocytes of the frog Xenopus laevis can be induced to express working membrane ion channels by introducing channel mRNA into their cytoplasm (heterologous expression) has greatly impacted the field of ion channel physiology. With the addition of site-directed mutagenesis techniques, the functional consequences of virtually any mutation can now be specifically and easily assessed. Here, we describe an effective procedure for investigating cardiac sodium channel gating (hNaV1.5) both in Xenopus oocytes, and in a mammalian expression system, human embryonic kidney (HEK) 293 cells. We describe cell attached patch clamp for oocytes, and whole cell voltage clamp in HEK 293 cells.