Histone deacetylases (HDACs) are key mediators of gene expression and, thus, major regulators of cell function. As such, HDACs play a role in orchestrating tumor biology, and the use of small inhibitors targeting theses proteins is attractive for the field of cancer therapy. Indeed, several HDAC inhibitors have received FDA-approval for the treatment of malignancies, while a myriad of these compounds continue to be evaluated in clinical trials. Besides their direct impact on tumor growth, HDAC inhibitors have been shown to increase immunogenicity of cancer cells, facilitating generation of a productive immune response against tumors. Immunotherapeutic approaches take advantage of the intrinsic ability of the immune system to manifest an anti-tumor response. Mechanisms of immune escape are often developed by cancer cells, neutralizing activity of the immune system. For example, upregulation of the PD1 ligands PDL1 and PDL2 by tumor cells negatively regulates the anti-tumor functions of PD1-expressing infiltrating T-cells. Importantly, strategies targeting this inhibitory axis have shown outstanding clinical benefit for the treatment of solid and hematological malignancies. The mechanisms by which HDAC inhibitors modulate tumor and immune cells biology were explored herein. Initially, treatment of melanoma cells with pan- and class I-selective HDAC inhibitors resulted in upregulation of PDL1 and PDL2 molecules. These effects were observed in mouse and human cell lines, as well as in tumor cells resected from metastatic melanoma patients. This upregulation was robust and sustained, lasting at least 96 hours in vitro, and validated in vivo using a B16F10 syngeneic mouse model. Enhanced expression of PDL1 mediated by HDAC inhibitors was found to result from enhanced histone acetylation at the PDL1 gene promoter region. Combination therapy of HDAC inhibition and PD1 blockade was explored in the tumor setting, leading to synergistic effects in terms of reducing melanoma progression and increasing survival of B16F10 melanoma-bearing mice. These data provide a clinical rationale for combination therapy of epigenetic modifiers (e.g. HDAC inhibitors) and PD1 blockade as means to augment cancer immunotherapy, improving patient outcomes. As a second pillar of this research, the impacts of HDAC-selective inhibition were explored on immune cell biology, since the broad nature of pan-HDAC inhibitors was shown to be detrimental to T-cells in vitro and in vivo. Based on screening assay results, novel implications of treating melanoma patient T-cells ex vivo with the HDAC6-selective inhibitor ACY1215 were investigated. Treatment with this compound was unique among pan- and isotype-selective HDAC inhibitors in modulating T-cell cytokine production and showing minimal impact of T-cell viability. ACY1215 tempered Th2 cytokine production (i.e. IL-4, IL-6 and IL-10), and maintained Th1 effector cytokines (e.g. IFNγ and IL-2). Furthermore, ACY1215 increased expression of surface markers, including CD69 activation marker and ICOS co-stimulatory molecule. In addition, ACY1215 treatment enhanced accumulation of central memory T-cells during ex vivo expansion of tumor infiltrating T-cells harvested from resected tumors of metastatic melanoma patients. Importantly, ACY1215-mediated inhibition improved tumor-killing capacity of T-cells. These results highlight an unexplored ability of selective HDAC inhibitor ACY1215 to augment T-cell expansion during protocols of adoptive cell therapy. While the discoveries presented here warrant further investigation of cellular and molecular mechanisms associated with ACY1215-treated T-cells, the clinic implications are clear and rapidly translatable.

BACKGROUND: Soft tissue sarcomas (STSs) are a diverse group of cancers that originate from mesenchymal tissue and are estimated to result in 13,130 new cases and 5,350 deaths this year. These neoplasms are hard to detect, which results in physicians struggling to treat late-stage STSs with a limited number of ineffective treatments. Currently, surgical excision is the primary treatment with radiation therapy administered when possible. However, even with optimal margins, the rate of recurrence is high, and the overall survival is low. There is a desperate need for new, more effective treatments. Immune checkpoint blockade (ICB) has recently had widespread success in treating melanoma, and in recent trials, SARC028 and Alliance A091401, have shown demonstrated activity of ICBs in STS in the neoadjuvant setting. Two histological subtypes of STS showed more promise than others: dedifferentiated liposarcoma (DDLPS) and undifferentiated pleomorphic sarcoma (UPS). Another issue plaguing the field of STS is that there is no universal indicator of response. The percentage of hyalinization found within the tumor was recently identified as a better marker of response than radiographic imaging or percent viable tumor. METHODS: This study was an investigator-initiated, single-center, randomized, open-label, phase II study (NCT03307616), in which 23 patients with either DDLPS of the retroperitoneum (RP) or UPS of the extremity/trunk (ET) were separated by disease into Cohort 1 and 2, respectively. Subjects in each cohort were randomized into two neoadjuvant treatment arms per cohort. Arm A (n=7) of Cohort 1 received nivolumab (anti-PD-1) monotherapy, while Arm B (n=7) of Cohort 1 received nivolumab and ipilimumab (anti-CTLA-4) combination therapy. Arm C (n=5) of Cohort 2 received nivolumab monotherapy and radiation therapy, whereas Arm D (n=4) of Cohort 2 received nivolumab/ipilimumab combination therapy and radiation therapy. A tumor biopsy was obtained before treatment, and another sample was taken during the primary treatment of surgical excision. These samples were processed and analyzed by a pathologist who determined the percentage of viable tumor, hyalinization, and necrosis in each sample. Radiographic imaging was also taken throughout to make RECIST 1.1 response determinations. RESULTS: The average treatment response (1 - % viable tumor) for Cohort 1 was 25 ± 23 and there was no difference between Arm A and Arm B, p=0.48. The average treatment response in Cohort 2 was higher at 85 ± 27, but there was also no significant difference between the arms, p = 0.46. The mean percent hyalinization for Cohort 1 was 13 ± 13%, and for Cohort 2 was 69 ± 35%. Again, there was no significant difference between the arms in the Cohort 1 or 2, p = 0.45 and p = 0.54, respectively. Lastly, the mean % necrosis in Cohort 1 was 13 ± 13 %, and in Cohort 2 was 17 ± 24%, and neither had significantly different results in the arms, p = 0.60 and p = 0.92. The RECIST 1.1 results were independent of the arms of the study, and the radiographic response (percent image change) did not correlate to any metric of histologic response. Those who received Ipilimumab had higher rates of adverse events. CONCLUSION: There is significant evidence that ICBs elicited a response in RP DDLPS and ET UPS, and the response of ET UPS was profound. However, there was no apparent benefit from the combination therapy compared to the monotherapy in either cohort. The higher response in ET UPS may be due to the additional radiation therapy or to the nature of UPS itself. Finally, radiographic imaging does not show the response which is apparent at the histological level, so treatment regimens and future experiments should no longer rely on radiographic imaging as a marker for response. / 2021-06-07T00:00:00Z

L'apport des anticorps immunomodulateurs ciblant PD-1, PD-L1 et CTLA-4 ont récemment révolutionné la prise en charge thérapeutique du cancer. Cependant, seule une minorité de patients développent des réponses objectives à ces traitements. Par conséquent, de nouvelles innovation thérapeutiques sont nécessaires afin d'augmenter l'immunogénicité des tumeurs et de surmonter la résistance à la thérapie contre les anticorps immunomodulateurs. Les propriétés oncolytiques de certains virus peuvent être exploitées afin de permettre un amorçage de l'immunité anti-tumorale. Différents virus oncolytiques (OVS) sont actuellement en développement clinique intense en combinaison avec des thérapies par anticorps immunomodulateurs. Nous avons trouvé qu'un vaccin viral pédiatrique disponible dans le commerce a des propriétés oncolytiques. Ce virus pédiatrique peut tuer directement les cellules cancéreuses, avec des caractéristiques de mort cellulaire immunogène. De plus, ce virus a des propriétés pro-inflammatoires et peut activer la voie NF-kB indépendamment des voies de danger cellulaire (TLR et IRF). Ces propriétés biologiques in vitro se traduisent in vivo en une activité anti-tumorale. L'Injection intra-tumorale du vaccin a des effets anti-tumoraux directs mais également à médiation immunitaire. De façon intéressante, dans des modèles de souris immunocompétentes porteuses de tumeurs murines, l'injection intra-tumorale de vaccin a un effet synergique avec des anti CTLA-4 permettant la guérison de 100% des souris. Les vaccins sont des produits pédiatriques et adultes de grade clinique. Par conséquent, des stratégies de vaccination in situ par injection intra-tumorale pourraient être rapidement mises en clinique / Immune checkpoint targeted therapies against PD-1, PD-L1 and CTLA-4 are currently revolutionizing cancer care. However, only a minority of patients develop objective responses with these treatments. Therefore, new therapeutic interventions are needed to increase the immunogenicity of tumors in order to overcome resistance to immune checkpoint blockade therapy. Oncolytic properties of common viruses can be exploited for the priming of anti-tumor immunity and such oncolytic viruses (OVs) are currently in intense clinical development in combination with immune checkpoint targeted therapies. We have found that commercially available virus vaccines do have oncolytic properties. These pediatric vaccine virus can directly kill cancer cells with features of immunogenic cell death. Moreover, it has pro-inflammatory properties and can activate the NF-Kb pathway in a toll-like receptor and IRF3 independent manner. These in vitro biological properties translate in vivo into anti-tumor activity. Intra-tumoral vaccine therapy has anti-tumor effects which are partly immune mediated. Interestingly, in immunocompetent murine pediatric tumor models, intra-tumoral injection overcome resistance and synergize with immune checkpoint targeted therapy. Vaccines are pediatric and adult clinical grade products. Therefore, in situ intra-tumoral immunization strategies could be implemented quickly in the clinic

Immune checkpoint blockade (ICB) shows remarkable clinical effects in patients with metastatic microsatellite-unstable (MSI) cancer. However, markers identifying potential non-responders are missing. We examined the prevalence of Beta-2-microglobulin (B2M) mutations, a common immune evasion mechanism, in stage IV MSI gastrointestinal cancer and its influence on metastatic pattern and patients’ survival under ICB. Twentyfive patients with metastatic, MSI gastrointestinal adenocarcinoma were included. Eighteen patients received ICB with pembrolizumab and one patient with nivolumab/ ipilimumab. Sequencing was performed to determine B2M mutation status. B2M mutations and loss of B2M expression were detected in 6 out of 25 stage IV MSI cancers. B2M mutations were strongly associated with exclusively peritoneal/peritoneal and lymph node metastases (p=0.0055). However, no significant differences in therapy response (25% vs. 46.6%, p>0.99) and survival (median PFS: 19.5 vs 33.0 months, p=0.74; median OS 39 months vs. not reached, p>0.99) were observed between B2Mmutant and B2M-wild type tumor patients. Among metastatic MSI GI cancers, B2Mmutant tumors represent a biologically distinct disease with distinct metastatic patterns. To assess ICB response in B2M-mutant MSI cancer patients, future studies need to account for the fact that baseline survival of patients with B2M-mutant MSI cancer may be longer than of patients with B2M-wild type MSI cancer.

New diagnostic methods and novel therapeutic agents spawn additional and heterogeneous information, leading to an increasingly complex decision-making process for optimal treatment of cancer. A great amount of information is collected in organ-specific multidisciplinary tumor boards (MDTBs). By considering the patient’s tumor properties, molecular pathological test results, and comorbidities, the MDTB has to consent an evidence-based treatment decision. Immunotherapies are increasingly important in today’s cancer treatment, resulting in detailed information that influences the decision-making process. Clinical decision support systems can facilitate a better understanding via processing of multiple datasets of oncological cases and molecular genetic information, potentially fostering transparency and comprehensibility of available information, eventually leading to an optimum treatment decision for the individual patient. We constructed a digital patient model based on Bayesian networks to combine the relevant patient-specific and molecular data with depended probabilities derived from pertinent studies and clinical guidelines to calculate treatment decisions in head and neck squamous cell carcinoma (HNSCC). In a validation analysis, the model can provide guidance within the growing subject of immunotherapy in HNSCC and, based on its ability to calculate reliable probabilities, facilitates estimation of suitable therapy options. We compared actual treatment decisions of 25 patients with the calculated recommendations of our model and found significant concordance (Cohen’s κ = 0.505, p = 0.009) and 84% accuracy.

PD-1 (Programmed Cell death protein -1) est un récepteur co-inhibiteur exprimé à la surface de lymphocytes T (LT) activés. Ce récepteur joue un rôle important dans le maintien de la tolérance périphérique tout en protégeant contre les maladies auto-immunes et inflammatoires. Cependant, une expression élevée et permanente de PD-1 et ses ligands PD-L1 et PD-L2 (PD-Ls) perturbe la réponse immunitaire contre les pathogènes et les cellules tumorales. Les inhibiteurs de points de contrôle immunitaires (ICI) ciblant l'axe PD-1/PD-Ls représentent aujourd’hui une avancé majeure dans le traitement de différents types de cancer, tant sur le plan de l’efficacité que de la tolérance. Le nivolumab (nivo) et le pembrolizumab (pembro) sont deux anticorps monoclonaux (AcM) anti-PD-1 qui bloquent l’interaction de PD-1 avec ses ligands. Ces AcM ont montré des résultats prometteurs dans le traitement de multiples types de cancers comme le mélanome, le cancer bronchique non à petites cellules, le carcinome à cellules rénales, etc. Malgré l’importance thérapeutique de nivo et de pembro dans le cancer, aucune étude n’a défini le devenir de PD-1 après la liaison à ces deux AcM. L’objectif de cette étude a été donc d’évaluer l’endocytose de PD-1 suite au liaison à des AcM anti-PD-1 (clone J110, nivo, pembro) et de déterminer s’il y a différence entre nivo et pembro vis à vis leur capacités à induire l'internalisation de PD-1. L’étude de l’endocytose de PD-1 a été réalisé sur des LT humains obtenus à partir du sang périphérique de donneurs sains et activés avec des Ac anti-CD3/anti-CD28 ou concanavaline A afin d’exprimer le récepteur PD-1. L’analyse des données par cytométrie en flux a montré que l’engagement de PD-1 avec l’Ac anti-PD-1 (clone J110) induit son endocytose dans les LT humains et que 50% de la totalité de PD-1 de surface est internalisé dans les premiers 30 minutes suivant l’incubation de cellules à 37°C, suivi d’un taux d’endocytose plus lent (56% en 60min). Notre étude a montré également que la liaison de nivo et de pembro au PD-1 induit son endocytose et que la plupart de récepteur est internalisée dans les 30 min suivant l’incubation de cellules à 37°C. Toutefois, 32 à 50% des récepteurs sont résistants à l’endocytose. L’analyse comparative de nivo et de pembro a révélé une différence statistiquement significative (p=0.03) entre le taux d’internalisation du complexe PD-1/nivo et celui du PD-1/pembro (46% versus 25% en 30min, respectivement). Même à des concentrations élevées de pembro, la liaison de nivo induit une meilleure internalisation de PD-1, ce qui suggère que nivo pourrait être plus efficace. Bien que les ICI comme nivo et pembro sont connus de bloquer l’interaction de PD-1 avec ses ligands, PD-L1 et PD-L2, notre étude a montré pour la première fois que ce deux AcM induisent aussi l’endocytose du récepteur PD-1 dans les LT humains avec des taux différents, et que 32% à 50% de récepteurs PD-1 sont résistants à l’endocytose. Ces résultats pourraient être exploités pour améliorer l’internalisation de PD-1 dans les LT humains et par la suite augmenter les potentiels thérapeutiques de nivolumab et de pembrolizumab dans le traitement du cancer. Mots clés : Récepteur PD-1, Ligands de PD-1, Lymphocytes T, Inhibiteurs de point de contrôle immunitaires, Anticorps anti-PD-1, Nivolumab, Pembrolizumab, Endocytose, Cancer / PD-1 (Programmed Cell death protein -1) is a co-inhibitory receptor expressed on the surface of activated T cells. It plays an important role in maintaining peripheral tolerance and protecting against autoimmune and inflammatory diseases. However, permanent expression of PD-1 and its ligands PD-L1/ PD-L2 (PD-Ls) disrupts the immune response against pathogens and tumor cells. Immune checkpoint blockade (ICB) targeting the PD-1/PD-Ls axis has revolutionized the treatment of many cancers. Nivolumab (nivo) and pembrolizumab (pembro) are two anti-PD-1 monoclonal antibodies (mAb) that block the interaction between PD-1 and its ligands. They have shown promising results in the treatment of multiple types of cancers such as melanoma, non-small cell lung cancer, renal cell carcinoma, etc. Surprisingly, despite the success of anti-PD-1 in cancer immunotherapy, no-one has defined the destiny of surface PD-1 following antibody binding. Therefore, the objective of my master thesis was to define the fate of surface PD-1 following antibody binding and whether different anti-PD-1 Abs in the clinic differ in their ability to induce PD-1 endocytosis. The study of PD-1 endocytosis was performed on human T lymphocytes obtained from peripheral blood of healthy donors and activated with anti-CD3/anti-CD28 Ab or concanavalin A to express PD-1 receptor. Data analysis by flow cytometry showed that following anti-PD-1 Ab binding, 50% of PD-1 becomes endocytosed by 30min. In addition, we found that the PD-1 receptor is internalised upon its engagement with nivo and pembro and that most of the receptor is endocytosed within 30 min. However, 32 to 50% of the receptors are resistant to endocytosis. The comparative analysis of nivo and pembro has revealed a statistically significant difference (p=0.03) between the internalisation rate of the PD-1/nivo complex versus PD-1/pembro (46% versus 25% by 30min, respectively). Even at high concentrations of pembro, nivo induces better internalization of PD-1, suggesting that nivo could be more effective than pembro. Our study showed for the first time that ICB involves not only in the blockade of PD-1/PD-Ls interaction, but also in the endocytosis of PD-1 receptors from the surface of human T-cells, which differs between nivolumab and pembrolizumab. These results could be exploited to increase the therapeutic potential of nivolumab and pembrolizumab in cancer treatment. Keywords: PD-1 receptor, PD-1 ligands, T lymphocytes, Immune checkpoint blockade, Anti-PD1 antibodies, Nivolumab, Pembrolizumab, Endocytosis, Cancer