Genomic and Immunophenotypic Landscape of Acquired Resistance to PD-(L)1 Blockade in Non-Small-Cell Lung Cancer.

PURPOSE: Although immune checkpoint inhibitors (ICI) have extended survival in patients with non-small-cell lung cancer (NSCLC), acquired resistance (AR) to ICI frequently develops after an initial benefit. However, the mechanisms of AR to ICI in NSCLC are largely unknown. METHODS: Comprehensive tumor genomic profiling, machine learning-based assessment of tumor-infiltrating lymphocytes, multiplexed immunofluorescence, and/or HLA-I immunohistochemistry (IHC) were performed on matched pre- and post-ICI tumor biopsies from patients with NSCLC treated with ICI at the Dana-Farber Cancer Institute who developed AR to ICI. Two additional cohorts of patients with intervening chemotherapy or targeted therapies between biopsies were included as controls. RESULTS: We performed comprehensive genomic profiling and immunophenotypic characterization on samples from 82 patients with NSCLC and matched pre- and post-ICI biopsies and compared findings with a control cohort of patients with non-ICI intervening therapies between biopsies (chemotherapy, N = 32; targeted therapies, N = 89; both, N = 17). Putative resistance mutations were identified in 27.8% of immunotherapy-treated cases and included acquired loss-of-function mutations in STK11, B2M, APC, MTOR, KEAP1, and JAK1/2; these acquired alterations were not observed in the control groups. Immunophenotyping of matched pre- and post-ICI samples demonstrated significant decreases in intratumoral lymphocytes, CD3e+ and CD8a+ T cells, and PD-L1-PD1 engagement, as well as increased distance between tumor cells and CD8+PD-1+ T cells. There was a significant decrease in HLA class I expression in the immunotherapy cohort at the time of AR compared with the chemotherapy (P = .005) and the targeted therapy (P = .01) cohorts. CONCLUSION: These findings highlight the genomic and immunophenotypic heterogeneity of ICI resistance in NSCLC, which will need to be considered when developing novel therapeutic strategies aimed at overcoming resistance.

T cell egress via lymphatic vessels is tuned by antigen encounter and limits tumor control.

Antigen-specific CD8+ T cell accumulation in tumors is a prerequisite for effective immunotherapy, and yet the mechanisms of lymphocyte transit are not well defined. Here we show that tumor-associated lymphatic vessels control T cell exit from tumors via the chemokine CXCL12, and intratumoral antigen encounter tunes CXCR4 expression by effector CD8+ T cells. Only high-affinity antigen downregulates CXCR4 and upregulates the CXCL12 decoy receptor, ACKR3, thereby reducing CXCL12 sensitivity and promoting T cell retention. A diverse repertoire of functional tumor-specific CD8+ T cells, therefore, exit the tumor, which limits the pool of CD8+ T cells available to exert tumor control. CXCR4 inhibition or loss of lymphatic-specific CXCL12 boosts T cell retention and enhances tumor control. These data indicate that strategies to limit T cell egress might be an approach to boost the quantity and quality of intratumoral T cells and thereby response to immunotherapy.

Cancer cell states recur across tumor types and form specific interactions with the tumor microenvironment.

Transcriptional heterogeneity among malignant cells of a tumor has been studied in individual cancer types and shown to be organized into cancer cell states; however, it remains unclear to what extent these states span tumor types, constituting general features of cancer. Here, we perform a pan-cancer single-cell RNA-sequencing analysis across 15 cancer types and identify a catalog of gene modules whose expression defines recurrent cancer cell states including 'stress', 'interferon response', 'epithelial-mesenchymal transition', 'metal response', 'basal' and 'ciliated'. Spatial transcriptomic analysis linked the interferon response in cancer cells to T cells and macrophages in the tumor microenvironment. Using mouse models, we further found that induction of the interferon response module varies by tumor location and is diminished upon elimination of lymphocytes. Our work provides a framework for studying how cancer cell states interact with the tumor microenvironment to form organized systems capable of immune evasion, drug resistance and metastasis.

Long-termin vivomonitoring of gliotic sheathing of ultrathin entropic coated brain microprobes with fiber-based optical coherence tomography.

Objective.Microfabricated neuroprosthetic devices have made possible important observations on neuron activity; however, long-term high-fidelity recording performance of these devices has yet to be realized. Tissue-device interactions appear to be a primary source of lost recording performance. The current state of the art for visualizing the tissue response surrounding brain implants in animals is immunohistochemistry + confocal microscopy, which is mainly performed after sacrificing the animal. Monitoring the tissue response as it develops could reveal important features of the response which may inform improvements in electrode design.Approach.Optical coherence tomography (OCT), an imaging technique commonly used in ophthalmology, has already been adapted for imaging of brain tissue. Here, we use OCT to achieve real-time,in vivomonitoring of the tissue response surrounding chronically implanted neural devices. The employed tissue-response-provoking implants are coated with a plasma-deposited nanofilm, which has been demonstrated as a biocompatible and anti-inflammatory interface for indwelling devices. We evaluate the method by comparing the OCT results to traditional histology qualitatively and quantitatively.Main results.The differences in OCT signal across the implantation period between the plasma group and the control reveal that the plasma-type coating of otherwise rigid brain probes (glass) only slightly improve the glial encapsulation in the brain parenchyma indicating that geometrical or mechanical influences are dominating the encapsulation process.Significance.Our approach can long-term monitor and compare the tissue-response to chronically-implanted neural probes with and withour plasma coating in living animal models. Our findings provide valuable insigh to the well acknowledged yet not solved challenge.

Magnetically Inserted Neural Electrodes: Tissue Response and Functional Lifetime.

Neural recording and stimulation have great clinical potential. Long-term neural recording remains a challenge, however, as implantable electrodes eventually fail due to the adverse effects of the host tissue response to the indwelling implant. Astrocytes and microglia attempt to engulf the electrode, increasing the electrical impedance between the electrode and neurons, and possibly pushing neurons away from the recording site. Faster insertion speed, finer tip geometry, smaller size, and lower material stiffness all seem to decrease damage caused by insertion and reduce the intensity of the tissue response. However, electrodes that are too small result in buckling, making insertion impossible. In this paper, we assess the viability of high-speed (27.8 m/s) deployment of 25 µm, ferromagnetic microelectrodes into rat brain. To characterize functionality of magnetically inserted electrodes, 4 Long-Evans rats were implanted for 31 days with impedance measurements and neural recordings taken daily. Performance was compared to 150 µm diameter PlasticsOne electrodes since 25 µm electrodes buckled during "slow speed" insertion. Platinum-iron magnetically inserted electrodes resolved single unit activity throughout the duration of the study in one rat, and saw no significant change (p=0.970) in impedance (4.54% increase) from day 0 (Z0 ≈ 144 kΩ,Z31 ≈ 150 kΩ). These findings provide a proof-of-concept for magnetic insertion as a viable insertion method that enables nonbuckling implantation of small (25 µm) microelectrodes, with potential for neural recording applications.