Rajiv Trehan

Functional tumor-specific CD8+ T cells are essential for effective anti-tumor immune response and immune checkpoint inhibitor therapy. Here we show that, compared to other organ sites, primary, metastatic liver tumors in murine models contain a higher number of tumor-specific CD8+ T cells which are also dysfunctional. High-dimensional, multi-omic analysis of patient samples reveals a higher frequency of exhausted tumor-reactive CD8+ T cells and enriched interactions between these cells and SPP1+ macrophages in profibrotic, alpha-SMA rich regions specifically in the liver. Differential pseudotime trajectory inference analysis reveals that extrahepatic signaling promotes an intermediate cell (IC) population in the liver, characterized by co-expression of VISG4, CSF1R, CD163, TGF-βR, IL-6R, and SPP1. Analysis of premetastatic adenocarcinoma patient samples reveals enrichment of this population may predict liver metastasis. These findings suggest a mechanism by which extrahepatic tumors drive liver metastasis by promoting an IC population that inhibits tumor-reactive CD8+ T cell function.

Polydimethyl siloxane (PDMS) has been used extensively for microfluidic devices due to its chemical properties allowing for rapid molding and versatile biological application. Soft lithography based PDMS fabrication primarily comprises casting from patterned photoresist on a silicon wafer. The patterned photoresist is often replaced with the cast PDMS as a more durable template mold for final PDMS fabrication that is less fragile and expensive. PDMS-PDMS double casting prolongs the longevity of soft lithography molds and reduces overall costs to microfuidic applications. A common end to the lifetime of PDMS negative masters is the risk of bonding between the replicate and mold and distorted topographrical features. This review examines common chemical and physical debonding approaches between PDMS-PDMS castings to exend the lifetime of PDMS masters.

BACKGROUND: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality. The combination of tremelimumab and durvalumab is now a standard treatment option for advanced HCC. OBJECTIVE: To study immune responses in HCC patients treated with tremelimumab and durvalumab. DESIGN: We treated 28 HCC patients with durvalumab, tremelimumab and locoregional therapies. We performed a high-dimensional multiomics analysis including whole exome sequencing, single-cell RNA seq, CO-Detection by indEXing, flow cytometry and multiplex cytokine/chemokine analysis of patients' blood and tumour samples and integrated this data to elucidate immune correlatives and response mechanisms. Mice with syngeneic HCC were treated with anti-PD-L1 plus anti-CTLA4 for hepatic lymphocytes, tumour-infiltrating lymphocytes and peripheral blood mononuclear cell analysis. RESULTS: The median overall survival was 19.2 months. Tumour tissue analysis revealed enhanced interferon responses, with stronger effects in responders. Gene set variation analysis indicated enhanced antigen presentation in responders. Spatial analysis revealed that non-responder tumours had higher numbers of Tregs located in neighbourhoods enriched with immune cells and expressed higher levels of ICOS and PD-1. Conversely, non-responder PD1+CD8+T in these Treg-enriched neighbourhoods expressed lower ICOS. Cell-communication analysis demonstrated that Treg-CD8+T interaction was enhanced in non-responder tissue. Peripheral blood analysis showed increased classical monocytes in responders and Tregs in non-responders. Treg-CD8+T interaction was confirmed in preclinical models. Finally, single-patient computational analysis from the all-across analysis was performed on 860 features, which led to the identification of multiomics feature sets including Treg features. CONCLUSION: Our study provides a blueprint for in-depth analysis of immune correlates in immunotherapy studies and demonstrates the importance of Treg distribution in HCC. TRIAL REGISTRATION NUMBERS: NCT02821754 and the EudraCT identifier: 2019-002767-98.