Andrew D. Weinberg

Helper T-cell subsets : phenotype, function and the role of lymphokines in regulating their development

We have concentrated here on the lymphokines which might serve to regulate the different pathways of precursor development. We suggest that, as a result of antigenic stimulation, specific precursor cells both proliferate and become committed to develop into either an effector cell, a memory cell or an anergized cell. Anergy has not been dealt with in this review, but it is likely to be one of the options available. The development of an effector population takes 4-7 d (quite analogous to the time it takes for CTLp to become CTL and for resting B to become Ab-forming cells). The effector populations are large, generally IL-2R-positive cells. These cells have upregulated many adhesion molecule systems [e.g., Pgp-1, LFA-1 and ICAM-1 (Swain unpublished)], but downregulated the Mel-14 homing receptor. Effectors are ready to respond to APC such as specific B cells with a rapid synthesis and secretion of lymphokines. The effector population is then quickly downregulated, both by the turn off of lymphokine synthesis/secretion and possibly by its own suicide. This kind of pattern makes teleological sense since the cells making such high titers of lymphokines could have many potent pleitropic effects. It also seems to be the strategy employed in the generation of other terminally differentiated effectors (such as CTL and plasma cells). The requirement for restimulation and the requirement for direct and perhaps prolonged contact between the helper effector and the APC-B cell can be expected to help ensure that these lymphokines are localized (reviewed in Swain & Dutton 1987, Swain & Croft 1990) and effectively delivered to specific responding cells. We postulate that at the same time, or perhaps subsequent to this, another set of signals drives precursors to generate prememory cells. Our studies suggest these emerging memory cells may be phenotypically unique and we postulate that they are specialized to become a long-lived population of memory cells that will persist indefinitely as a protective population of increased frequency for the antigen encountered and which is also able to respond more rapidly and effectively. The greater effectiveness of the memory response would thus be due to dramatically increased frequency, to characteristic and stable changes in adhesion molecule expression and to the fact that, in addition to IL-2, resting memory cells also secrete at least low titers of IL-3, IL-4, IFN-gamma and other lymphokines upon initial restimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

OX40, PD-1 and CTLA-4 are selectively expressed on tumor-infiltrating T cells in head and neck cancer

The tumor microenvironment of squamous cell carcinoma of the head and neck (SCCHN) has been shown to be immune suppressive. Therefore, strategies aimed at overcoming this issue could have a positive therapeutic impact. Hence, we investigated the expression of the known immune‐modulatory proteins OX40, programmed cell death protein 1 (PD‐1) and cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4) in SCCHN on different T‐cell subsets of tumor‐infiltrating lymphocytes (TIL) to ascertain whether these proteins could potentially be targeted alone or in combination for future clinical trials. T cells from peripheral blood (PBL) and tumor were analyzed for the expression of OX40, PD‐1 and CTLA‐4 in 29 patients undergoing surgery. These proteins were all expressed significantly higher in T‐cell subsets isolated from tumors compared with PBL of the same patient. OX40 expression was significantly greater in the TIL regulatory T‐cell (Treg) population relative to conventional CD4 and CD8 TIL or the Treg isolated from PBL. PD‐1 expression was increased in all T‐cell subsets relative to PBL. CTLA‐4 was also increased in all TIL subsets relative to blood, and similar to OX40, its highest level of expression was observed in the Treg TIL. The highest frequency of PD‐1, CTLA‐4 and OX40 triple‐positive cells were found in the Treg population isolated from the tumor. We analyzed both human papilloma virus‐positive and ‐negative patients and found similar levels and expression patterns of these two patient populations for all three proteins. These data suggest that there may be therapeutic advantages of targeting these pathways independently or in combination for patients with this disease.

Combinational Immunotherapy with Allo-DRibble Vaccines and Anti-OX40 Co-Stimulation Leads to Generation of Cross-Reactive Effector T Cells and Tumor Regression

It is well-known that vaccines comprising of irradiated whole tumor cells or tumor-derived heat shock proteins can generate tumor-specific immune responses. In contrast, we showed recently that vaccines composed of autophagosomes (DRibbles) derived from syngeneic sarcomas could induce cross-reactive T-cell responses and cross-protection against the tumor. This unusual property of DRibbles was related to the selective recruitment of defective ribosomal products (DRiPs) and other short-lived proteins (SLiPs) into autophagosomes via sequestosome (SQSTM1, p62) mediated association of ubiquitinated SLiPs to the autophagy gene product LC3. Here, we extend our observations to mammary carcinomas from mice of different genetic background. We demonstrated that combined of intranodal administration of autologous or allogeneic DRibbles together with anti-OX40 antibody led to robust proliferation, expansion, and differentiation of memory and effector T cells. We also showed that SLiPs is an excellent source of antigen for cross-priming of CD8+ T-cells that recognize shared tumor antigens in the context of host MHC class I molecules. Thus, our results provide a strong basis for novel clinical trials that combine allogeneic “off-the-shelf” DRibble vaccines together with antibodies against co-stimulatory molecules.

Caloric restriction maintains OX40 agonist-mediated tumor immunity and CD4 T cell priming during aging

Immune responses wane during aging, posing challenges to the potential effectiveness of cancer immunotherapies. We previously demonstrated that in the context of a promising immunotherapeutic, OX40 agonist (αOX40), older animals exhibited impaired anti-tumor immune responses and diminished CD4 T cell effector differentiation. In this study, we hypothesized that tumor immune responses could be maintained during aging through caloric restriction (CR) or dietary supplementation with resveratrol (RES), a CR mimetic. Mice were placed on either a calorically restricted diet or a RES-formulated diet starting between 4 and 6xa0months of age and continued until mice reached 12xa0months of age. Tumor immune responses were assessed after challenging with either sarcoma or breast tumor cells followed by αOX40 treatment. Our results show that CR, but not RES, maintained OX40-mediated anti-tumor immunity. In addition, CR fully sustained antigen-specific CD4 T cell priming in aged hosts (12xa0months old), whereas tumor-specific CD8 T cell priming was not fully maintained compared to young reference animals (2xa0months old). Thus, CR appears to maintain immunological fitness of the CD4 T cell priming environment during aging, which is critical for optimal OX40-mediated responses.

Co-expression of CD39 and CD103 identifies tumor-reactive CD8 T cells in human solid tumors

Identifying tumor antigen-specific T cells from cancer patients has important implications for immunotherapy diagnostics and therapeutics. Here, we show that CD103+CD39+ tumor-infiltrating CD8 T cells (CD8 TIL) are enriched for tumor-reactive cells both in primary and metastatic tumors. This CD8 TIL subset is found across six different malignancies and displays an exhausted tissue-resident memory phenotype. CD103+CD39+ CD8 TILs have a distinct T-cell receptor (TCR) repertoire, with T-cell clones expanded in the tumor but present at low frequencies in the periphery. CD103+CD39+ CD8 TILs also efficiently kill autologous tumor cells in a MHC-class I-dependent manner. Finally, higher frequencies of CD103+CD39+ CD8 TILs in patients with head and neck cancer are associated with better overall survival. Our data thus describe an approach for detecting tumor-reactive CD8 TILs that will help define mechanisms of existing immunotherapy treatments, and may lead to future adoptive T-cell cancer therapies.Identifying and enumerating tumor-specific CD8 T cells are important for assessing cancer prognosis and therapy efficacy. Here the authors show that CD39 and CD103 mark a subset of tumor-infiltrating CD8 T cells that are tumor-reactive and exhibit characteristics of exhausted or tissue-resident memory T cells.

Abstract 37: Anti-OX40 (MEDI6469) prior to definitive surgical resection in patients with head and neck squamous cell carcinoma

Background: Head and neck squamous cell carcinomas (HNSCC) produce suppressive factors that impair the immune system, thus limiting effective antitumor immunity. OX40 is a member of the tumor necrosis factor (TNF) receptor family and its biologic activity leads to potent co-stimulation, which can enhance T-cell memory, proliferation and antitumor activity in patients with metastatic cancer. However, its effect on wound healing and the optimal timing of administration in relation to surgery to induce immune changes within the tumor microenvironment (TME) is not known. Objectives: To determine the safety and peak immunologic activity of neoadjuvant anti-OX40 treatment administered prior to definitive surgical resection in patients with locoregionally advanced HNSCC. Methods: Between January 2016 and July 2016, 10 patients with locoregionally advanced HNSCC were enrolled into this phase Ib neoadjuvant time course trial testing a murine antibody to OX40 (MEDI6469) administered 2 days, 1 week and 2 weeks prior to definitive surgical resection. In order to assess changes in the tumor microenvironment (TME), a tissue biopsy and peripheral blood samples were obtained prior to MEDI6469 infusion and tissue was also harvested at the time of surgical resection from the primary tumor site, metastatic and draining lymph nodes along with peripheral blood. Assessments of tumor infiltrating lymphocyte (TIL) populations were performed based on flow cytometry and fluorescent multiplex immunohistochemistry (mIHC); other circulating immunologic parameters that correlate with changes induced by MEDI6469 administration were also measured. These immune changes were assessed and compiled in a “cumulative suppression index,” which incorporates immunosuppressive elements within the tumor, such as FoxP3+ and PD-L1+ cells, to be correlated with clinical variables and outcome. Surgical complications were described using the Clavien-Dindo grading scale. Clinical trial information: NCT02274155. Results: MEDI6469 administration was well tolerated and there were no grade 3 or 4 adverse events (AEs) attributable to anti-OX40 treatment. The toxicity profile was mild, most commonly consisting of low-grade fever prior to surgery, which was performed in all patients without delay. Postoperative grade 3 and 4 complications per Clavien-Dindo scale were observed in two patients. Immunologic changes were observed at all time courses with significant activation and proliferation of CD4+ and CD8+ central and effector memory T-cell populations in both the TME and circulation occurring between 12 and 19 days following MEDI6469 infusion. Ki67 was specifically induced in the TME and on peripheral blood PBMCs after MEDI6469 administration, returning to baseline at Day 55. Up-regulation of PD-L1 was also seen in the tumor post treatment in the majority of specimens. In the tumor, expression of CD39, ICOS and PD-1 is increased on CD4+ T cells in almost all patients and a recently identified tumor-reactive T-cell subset of CD39+CD103+CD8+ T cells, with resident memory phenotype, was increased in some patients. Conclusion: Preoperative MEDI6469 administration prior to surgery is feasible and safe in patients with HNSCC and results in activation and proliferation of T cell populations and up-regulation of PD-L1 in tumor cells occurring between 12 and 19 days following infusion. Citation Format: R. Bryan Bell, Rom S. Leidner, Rebekka A. Duhen, Carmen Ballesteros-Merino, Zipei Feng, Yoshinobu Koguchi, Carlo B. Bifulco, Brendan D. Curti, Walter J. Urba, Bernard A. Fox, Andrew D. Weinberg. Anti-OX40 (MEDI6469) prior to definitive surgical resection in patients with head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; April 23-25, 2017; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(23_Suppl):Abstract nr 37.

Finding the right balance: aOX40 immunotherapy enhances effector T cell function without impairing regulatory T cells intrinsic suppressive capacity in mouse tumor models

Meeting abstractsnnExpression of the co-stimulatory molecule OX40 is induced after TCR ligation on conventional T cells and the importance of OX40 in promoting proliferation, effector function, and survival of activated T cells are illustrated in multiple disease models. Paradoxically, CD4+Foxp3+