Nanobody-based CTLA4 inhibitors for immune checkpoint blockade therapy of canine cancer patients

AbstractCancer is the leading cause of death in the geriatric dog population. Currently, the use of immune checkpoint inhibitors (ICIs) such as anti-CTLA4 antibodies has markedly improved the prognosis of several cancers in their advanced stages. However, ICIs targeting CTLA4 blockade to treat canine cancer patients are yet to define. In this study, we sought to develop, characterize and assess whether chimeric heavy chain only antibodies (cHcAbs) against CTLA4 are viable therapeutic candidates for the treatment of canine cancers. Anti-CTLA4 nanobodies (Nbs) were identified from a yeast nanobody (Nb) library using magnetic-assisted cell sorting (MACS) and flow cytometry. cHcAbs were engineered by genetically fusing the DNA sequences coding for anti-CTLA4 Nbs with the Fc domain of the subclass B of canine IgG. Recombinant cHcAbs were purified from ExpiCHO-S cells. Stable cell lines expressing canine CTLA4 and FcγRI were used to elucidate the binding ability and specificity of cHcAbs. PBMCs isolated from healthy dogs were used to evaluate the ability of cHcAbs to activate canine PBMCs (cPBMCs). Novel Nbs were identified using the extracellular domain of canine CTLA4 protein to screen a fully synthetic yeast nanobody library. Purified Nbs bind specifically to natïve canine CTLA4. We report that chimeric HcAbs, which were engineered by fusing the anti-CTLA4 Nbs and Fc region of subclass B of canine IgG, were half the size of a conventional mAb and formed dimers. The chimeric HcAbs specifically binds both with canine CTLA4 and Fcγ receptors. As the binding of Nbs overlapped with the MYPPPY motif of canine CTLA4, these Nbs were expected to sterically disrupt the interaction of canine CTLA4 to B-7s. Like their human counterpart, canine CTLA4 was expressed on helper T cells and a small subset of cytotoxic T cells. Canine Tregs also constitutively expressed CTLA4, and stimulation with PMA/Ionomycin dramatically increased expression of CTLA4 on the cell surface. Stimulation of cPBMCs in the presence of agonistic anti-CD3 Ab and cHcAb6 significantly increased the expression of IFN-γ as compared to the isotype control. This study identifies a novel nanobody-based CTLA4 inhibitor for the treatment of canine cancer patients.

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Nanobody-based CTLA4 inhibitors for immune checkpoint blockade therapy of canine cancer patients

10.21203/rs.3.rs-765466/v1 ◽

2021 ◽

Author(s):

Jonathan Marable ◽

Damien Ruiz ◽

Anil K. Jaiswal ◽

Ritankar Bhattacharya ◽

Robert Pantazes ◽

...

Keyword(s):

T Cells ◽

Cancer Patients ◽

Dna Sequences ◽

Immune Checkpoint ◽

Checkpoint Inhibitors ◽

Cytotoxic T Cells ◽

Immune Checkpoint Blockade ◽

Small Subset ◽

Canine Cancer ◽

Advanced Stages

Abstract Background Cancer is the leading cause of death in the geriatric dog population. Currently, the use of immune checkpoint inhibitors (ICIs) such as anti-CTLA4 antibodies has markedly improved the prognosis of several cancers in their advanced stages. However, ICIs targeting CTLA4 blockade to treat canine cancer patients are yet to define. In this study, we sought to develop, characterize and assess whether chimeric heavy chain only antibodies (cHcAbs) against CTLA4 are viable therapeutic candidates for the treatment of canine cancers.Methods Anti-CTLA4 nanobodies (Nbs) were identified from a yeast nanobody (Nb) library using magnetic-assisted cell sorting (MACS) and flow cytometry. cHcAbs were engineered by genetically fusing the DNA sequences coding for anti-CTLA4 Nbs with the Fc domain of the subclass B of canine IgG. Recombinant cHcAbs were purified from ExpiCHO-S cells. Stable cell lines expressing canine CTLA4 and FcγRI were used to elucidate the binding ability and specificity of cHcAbs. PBMCs isolated from healthy dogs were used to evaluate the ability of cHcAbs to activate canine PBMCs.Results Novel Nbs were identified using the extracellular domain of canine CTLA4 protein to screen a fully synthetic yeast nanobody library. Purified Nbs bind specifically to natïve canine CTLA4. We report that chimeric HcAbs, which were engineered by fusing the anti-CTLA4 Nbs and Fc region of subclass B of canine IgG, were half the size of a conventional mAb and formed dimers. The chimeric HcAbs specifically binds both with canine CTLA4 and FcƳ receptors. As the binding of Nbs overlapped with the MYPPPY motif of canine CTLA4, these Nbs were expected to sterically disrupt the interaction of canine CTLA4 to B-7s. Like their human counterpart, canine CTLA4 was expressed on helper T cells and a small subset of cytotoxic T cells. Canine Tregs also constitutively expressed CTLA4, and stimulation with PMA/Ionomycin dramatically increased expression of CTLA4 on the cell surface. Stimulation of canine PBMCs in the presence of agonistic anti-CD3 Ab and cHcAb6 significantly increased the expression of IFN-γ as compared to the isotype control.Conclusions This study identifies a novel nanobody-based CTLA4 inhibitor for the treatment of canine cancer patients. Furthermore, this approach provides a critical proof-of-concept for developing nanobody-based humanized anti-CTLA4 therapy for advanced stages of cancers.

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Treatment with therapeutic anticoagulation is not associated with immunotherapy response in advanced cancer patients

Journal of Translational Medicine ◽

10.1186/s12967-021-02712-w ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Paul Johannet ◽

Amelia Sawyers ◽

Nicholas Gulati ◽

Douglas Donnelly ◽

Samuel Kozloff ◽

...

Keyword(s):

Cancer Patients ◽

Advanced Cancer ◽

Immune Checkpoint ◽

Checkpoint Inhibitors ◽

Objective Response ◽

Progression Free Survival ◽

Immune Checkpoint Blockade ◽

Coagulation Cascade ◽

Advanced Cancer Patients ◽

Clinical Endpoints

Abstract Background Recent preclinical data suggest that there may be therapeutic synergy between immune checkpoint blockade and inhibition of the coagulation cascade. Here, we investigate whether patients who received immune checkpoint inhibitors (ICI) and were on concomitant anticoagulation (AC) experienced better treatment outcomes than individuals not on AC.Affiliation: Kindly confirm if corresponding authors affiliation is identified correctly.The corresponding author's affiliation is correct. Methods We studied a cohort of 728 advanced cancer patients who received 948 lines of ICI at NYU (2010–2020). Patients were classified based on whether they did (n = 120) or did not (n = 828) receive therapeutic AC at any point during their treatment with ICI. We investigated the relationship between AC status and multiple clinical endpoints including best overall response (BOR), objective response rate (ORR), disease control rate (DCR), progression free survival (PFS), overall survival (OS), and the incidence of bleeding complications.Affiliations: Journal instruction requires a country for affiliations; however, this is missing in affiliations 1 to 5. Please verify if the provided country is correct and amend if necessary.The country is correct for all affiliations (1 - 5). Results Treatment with AC was not associated with significantly different BOR (P = 0.80), ORR (P =0.60), DCR (P =0.77), PFS (P = 0.59), or OS (P =0.64). Patients who received AC were significantly more likely to suffer a major or clinically relevant minor bleed (P = 0.05). Conclusion AC does not appear to impact the activity or efficacy of ICI in advanced cancer patients. On the basis of our findings, we caution that there is insufficient evidence to support prospectively evaluating the combination of AC and immunotherapy.

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Immune checkpoint blockade in the treatment of malignant tumor: current statue and future strategies

Cancer Cell International ◽

10.1186/s12935-021-02299-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Wenwen Yang ◽

Caining Lei ◽

Shaoming Song ◽

Wutang Jing ◽

Chuanwei Jin ◽

...

Keyword(s):

T Cells ◽

Malignant Tumor ◽

Immune Checkpoint ◽

Cytotoxic T Lymphocyte ◽

Malignant Tumors ◽

Checkpoint Inhibitors ◽

Immune Surveillance ◽

Immune Checkpoint Blockade ◽

Checkpoint Response ◽

Inhibitory Molecule

AbstractAfter being stagnant for decades, there has finally been a paradigm shift in the treatment of cancer with the emergence and application of immune checkpoint inhibitors (ICIs). The most extensively utilized ICIs are targeting the pathways involving programmed death-1 (PD-1) and cytotoxic T-lymphocyte associated protein 4 (CTLA-4). PD-1, as an crucial immune inhibitory molecule, by and large reasons the immune checkpoint response of T cells, making tumor cells get away from immune surveillance. Programmed cell death ligand-1 (PD-L1) is exceptionally expressed in most cancers cells and approves non-stop activation of the PD-1 pathway in the tumor microenvironment. PD-1/PD-L1 inhibitors can block the combination of PD-1 and PD-L1, inhibit hostile to regulatory signals, and restore the activity of T cells, thereby bettering immune response. The current researchers assume that the efficacy of these drugs is related to PD-L1 expression in tumor tissue, tumor mutation burden (TMB), and other emerging biomarkers. Although malignant tumors can benefit from the immunotherapy of PD-1/PD-L1 inhibitors, formulating a customized medication model and discovering biomarkers that can predict efficacy are the new trend in the new era of malignant tumor immunotherapy. This review summarizes the mechanism of action of PD-1/PD-L1 inhibitors, their clinical outcomes on various malignant tumors, their efficacy biomarkers, as well as predictive markers of irAEs.

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646 Evaluating a preclinical model of contact hypersensitivity for skin immune checkpoint toxicity

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0646 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A683-A683

Author(s):

Barbara Ma ◽

Abhinav Jaiswal ◽

K Sanjana Devi ◽

Qingrong Huang ◽

Joy Hsu ◽

...

Keyword(s):

T Cells ◽

Adverse Events ◽

Clin Oncol ◽

Cd8 T Cells ◽

Murine Model ◽

Immune Checkpoint ◽

Immune Checkpoint Inhibitors ◽

Checkpoint Inhibitors ◽

Immune Checkpoint Blockade ◽

Contact Hypersensitivity

BackgroundImmune checkpoint inhibitors (ICIs) are limited by the high incidence of immune-related adverse events (irAEs) occurring in up to 40% of solid tumor patients on anti-PD-1 monotherapy 1 2 and 72% in anti-CTLA-4/anti-PD-1 combination.3 4 These toxicities can cause treatment cessation, hospitalization and even death.5–7 IrAEs are variable in severity, timing, onset, and remain poorly understood. Amongst the different toxicities, skin irAEs are most frequent, occur the earliest, and are correlated with a positive prognosis.4 8 However, there is a lack of preclinical models to study checkpoint toxicity. We evaluated a murine model of allergic contact dermatitis (contact hypersensitivity to 2,4-dinitrofluorobenzene) that is mediated by CD8+ T cells to gain a mechanistic understanding of skin checkpoint toxicity.MethodsC57BL/6 mice (n = 5 per group) were sensitized epicutaneously on shaved flank with hapten 0.5% DNFB on day -5 and elicited on their ears with DNFB on day 0. Starting four weeks later, mice were treated with either anti-programmed cell death protein (PD-1) or isotype. At the time of the first recall challenge only, mice were given either anti-PD-1 or isotype. Mice received subsequent rechallenges with DNFB to the ears and ear swelling was measured at various time points. Mice were depleted of circulating or skin CD8+ T cells by anti-CD8 mAbs from day 29 onwards, and maintained weekly, as in this model CD8+ T cells are the main hapten responder population. Samples were collected for histochemistry and analyzed by flow cytometry.ResultsOur data indicate that despite the depletion of circulating T cells, anti-PD-1 recipients mount a higher initial recall response to contact agents. Higher ear swelling was observed with increased inflammation in these mice. Our data suggest anti-PD-1 can liberate local T cell responses in the absence of a contribution from blood, and may offer a model to test therapeutic interventions to alleviate peripheral immune toxicities.ConclusionsOur results suggest that this murine model of contact hypersensitivity represents a potential model for skin immune checkpoint toxicities. This model of locally-mediated inflammatory recall may advance the goal of uncoupling toxicity from efficacy in patients with immune-related adverse events.Ethics ApprovalThe animal study was approved by Weill Cornell Medicine’s IACUC; approval number D16-00186.ReferencesNaidoo J, Page DB, Li BT, et al. Toxicities of the anti-PD-1 and anti-PD-L1 immune checkpoint antibodies. Ann Oncol 2015;26(12):2375–91. doi: 10.1093/annonc/mdv383.Belum VR, Benhuri B, Postow MA, et al. Characterisation and management of dermatologic adverse events to agents targeting the PD-1 receptor. Eur J Cancer 2016;60:12–25. doi: 10.1016/j.ejca.2016.02.010.Postow MA, Sidlow R, Hellmann MD. Immune-Related Adverse Events Associated with Immune Checkpoint Blockade. N Engl J Med 2018;378(2):158–168. doi: 10.1056/NEJMra1703481.Martins F, Sofiya L, Sykiotis GP, et al. Adverse effects of immune-checkpoint inhibitors: epidemiology, management and surveillance. Nat Rev Clin Oncol 2019;16(9):563–580. doi: 10.1038/s41571-019-0218-0.Puzanov I, Diab A, Abdallah K, et al. Managing toxicities associated with immune checkpoint inhibitors: consensus recommendations from the society for immunotherapy of cancer (SITC) Toxicity Management Working Group. J Immunother Cancer 2017;5(1):95. doi: 10.1186/s40425-017-0300-z.Wills B, Brahmer JR, Naidoo J. Treatment of complications from immune checkpoint inhibition in patients with lung cancer. Curr Treat Options Oncol 2018;19(9):46. doi: 10.1007/s11864-018-0562-9.Michot JM, Bigenwald C, Champiat S, et al. Immune-related adverse events with immune checkpoint blockade: a comprehensive review. Eur J Cancer 2016;54:139–148. doi: 10.1016/j.ejca.2015.11.016.Phillips GS, Wu J, Hellmann MD, et al. Treatment outcomes of immune-related cutaneous adverse events. J Clin Oncol 2019:JCO1802141. doi: 10.1200/JCO.18.02141.

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The Risks and Benefits of Immune Checkpoint Blockade in Anti-AChR Antibody-Seropositive Non-Small Cell Lung Cancer Patients

Cancers ◽

10.3390/cancers11020140 ◽

2019 ◽

Vol 11 (2) ◽

pp. 140 ◽

Cited By ~ 8

Author(s):

Koichi Saruwatari ◽

Ryo Sato ◽

Shunya Nakane ◽

Shinya Sakata ◽

Koutaro Takamatsu ◽

...

Keyword(s):

Lung Cancer ◽

Cancer Patients ◽

Immune Checkpoint ◽

Immune Checkpoint Inhibitors ◽

Checkpoint Inhibitors ◽

Antibody Therapy ◽

Lung Squamous Cell Carcinoma ◽

Complete Response ◽

Immune Checkpoint Blockade ◽

Advanced Cancer Patients

Background: Anti-programmed cell death 1 (PD-1) monoclonal antibodies (Abs) unleash an immune response to cancer. However, a disruption of the immune checkpoint function by blocking PD-1/PD-ligand 1(PD-L1) signaling may trigger myasthenia gravis (MG) as a life-threatening immune-related adverse event. MG is a neuromuscular disease and is closely associated with being positive for anti-acetylcholine receptor (anti-AChR) Abs, which are high specific and diagnostic Abs for MG. Methods: A 72-year-old man was diagnosed with chemotherapy-refractory lung squamous cell carcinoma and nivolumab was selected as the third-line regimen. We describe the first report of an anti-AChR Ab-seropositive lung cancer patient achieving a durable complete response (CR) to an anti-PD-1 antibody therapy. To further explore this case, we performed multiplex immunofluorescence analysis on a pretreatment tumor. Results: The patient achieved a durable CR without developing MG. However, the levels of anti-AChR Abs were elevated during two years of anti-PD-1 antibody therapy. The tumor of the subclinical MG patient had high PD-L1 expression and an infiltrated–inflamed tumor immune microenvironment. Conclusions: This study suggests that immune checkpoint inhibitors can be safely used and provide the benefits for advanced cancer patients with immunologically ‘hot’ tumor even if anti-AChR Abs are positive. Although careful monitoring clinical manifestation in consultation with neurologist is needed, immune checkpoint inhibitors should be considered as a treatment option for asymptomatic anti-AChR Ab-seropositive cancer patients.

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T-Cell Exhaustion in Mycobacterium tuberculosis and Nontuberculous Mycobacteria Infection: Pathophysiology and Therapeutic Perspectives

Microorganisms ◽

10.3390/microorganisms9122460 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2460

Author(s):

Andrea Lombardi ◽

Simone Villa ◽

Valeria Castelli ◽

Alessandra Bandera ◽

Andrea Gori

Keyword(s):

T Cells ◽

Mycobacterium Tuberculosis ◽

Immune Checkpoint ◽

Nontuberculous Mycobacteria ◽

Checkpoint Inhibitors ◽

Immune Checkpoint Blockade ◽

Chronic Infections ◽

Mycobacterium Tuberculosis Infection ◽

Phenotypic Profile ◽

Immune Exhaustion

Immune exhaustion is a condition associated with chronic infections and cancers, characterized by the inability of antigen-specific T cells to eliminate the cognate antigen. Exhausted T cells display a peculiar phenotypic profile and exclusive functional characteristics. Immune exhaustion has been described in patients with Mycobacterium tuberculosis infection, and cases of tuberculosis reactivation have been reported in those treated with immune checkpoint inhibitors, drugs able to re-establish T-cells’ function. Exhausted T CD8+ cells’ profile has also been described in patients with infection due to nontuberculous mycobacteria. In this review, we initially provide an overview of the mechanisms leading to immune exhaustion in patients infected by Mycobacterium tuberculosis and nontuberculous mycobacteria. We then dissect the therapeutic perspectives related to immune checkpoint blockade in patients with these infections.

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Comprehensive Analysis of the Immune Microenvironment Reveals that CD52 is a Marker for Breast Cancer Treatment with Immune Checkpoint Inhibitors

10.21203/rs.3.rs-1078018/v1 ◽

2021 ◽

Author(s):

Qiang Wang ◽

Xuxu Liu ◽

Pengfei Wang ◽

Dankun Luo ◽

Wenqi Gao ◽

...

Keyword(s):

Breast Cancer ◽

T Cells ◽

Cancer Patients ◽

Immune Checkpoint ◽

Immune Checkpoint Inhibitors ◽

Checkpoint Inhibitors ◽

Adaptive Immune Response ◽

Breast Cancer Patients ◽

Immune Microenvironment ◽

Adaptive Immune

Abstract Background:Breast cancer (BC) is one of the most common tumors in women. Recent years, immune checkpoint inhibitors (ICIs) have brought good news to BC patients. Although significant achievements have been made through treatment with ICIs, some people who experience serious immune-related adverse events (IrAEs) are still insensitive to this approach. The response to ICI treatment depends on the type of tumor microenvironment (TME). Methods:WGCNA (weighted gene co-expression network analysis), ESTIMATE algorithm, LASSO regression analysis, survival analysis, functional enrichment analysis are conducted to analyze the BC data in the TCGA database. Immunohistochemistry was used to verify the expression of CD52 in BC.Results:WGCNA and ESTIMATE algorithm found that the CD52 is closely related to the immune microenvironment. CD52 highly expressed in various breast cancer subtypes, and patients with high expression of CD52 have longer survival time. Compared with the low-CD52 group, the high-CD52 group had more immune cell infiltration. TIMER database verification results showed that CD8+ T cells, activated memory CD4 T cells, memory B cells, γδ T cells, and Tregs were positively correlated with CD52 expression, while M2 macrophages were negatively correlated. CD52 can change the trend of TIC (CD8+ T) and tumor-associated macrophage (TAM) infiltration with respect to the survival time of breast cancer patients. Based on the expression of CD52, we explored the relationship between CD52 and the adaptive immune response (AIR). CD52 is a marker of AIR stratification in breast cancer patients. We constructed a CD52-related adaptive immune response gene signature (CD52rAIRGsig) which is an independent prognostic factor for breast cancer and related to genome instability and the immune cells infiltration in the TME. CD52 and CD52rAIRGsig were associated with PD-1 signaling and immune checkpoint inhibitor markers, which proves that patients with high CD52 expression and low risk of CD52rAIRGsig are more suitable for ICI treatment. We then screened chemotherapeutics for personalized medicine based on CD52rAIRGsig. Conclusion:Therefore, we have discovered a new marker to guide the treatment and prognosis of breast cancer patients with ICIs. This provides a combined treatment strategy including different combinations of ICIs combined with chemotherapeutic drugs to treat breast cancer.

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Surface engineering of oncolytic adenovirus for combinations of immune checkpoint blockade and virotherapy

Biomaterials Science ◽

10.1039/d1bm00928a ◽

2021 ◽

Author(s):

Peng Lv ◽

Xiaomei Chen ◽

Shiying Fu ◽

En Ren ◽

Chao Liu ◽

...

Keyword(s):

Cancer Treatment ◽

Cancer Immunotherapy ◽

Cancer Patients ◽

Immune Checkpoint ◽

Immune Checkpoint Inhibitors ◽

Surface Engineering ◽

Checkpoint Inhibitors ◽

Immune Checkpoint Blockade ◽

Oncolytic Adenovirus ◽

Checkpoint Blockade

Advances in the development of modern cancer immunotherapy and immune checkpoint inhibitors have dramatically changed the landscape of cancer treatment. However, most cancer patients are refractory to immune checkpoint inhibitors...

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Therapy of lymphoma by immune checkpoint inhibitors: the role of T cells, NK cells and cytokine-induced tumor senescence

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-001660 ◽

2021 ◽

Vol 9 (1) ◽

pp. e001660

Author(s):

Fatima Ahmetlic ◽

Josia Fauser ◽

Tanja Riedel ◽

Vera Bauer ◽

Carolin Flessner ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Growth ◽

Nk Cells ◽

Immune Checkpoint ◽

Immune Checkpoint Inhibitors ◽

Checkpoint Inhibitors ◽

Immune Checkpoint Blockade ◽

Ifn Γ

BackgroundAlthough antibodies blocking immune checkpoints have already been approved for clinical cancer treatment, the mechanisms involved are not yet completely elucidated. Here we used a λ-MYC transgenic model of endogenously growing B-cell lymphoma to analyze the requirements for effective therapy with immune checkpoint inhibitors.MethodsGrowth of spontaneous lymphoma was monitored in mice that received antibodies targeting programmed cell death protein 1 and cytotoxic T lymphocyte-associated protein-4, and the role of different immune cell compartments and cytokines was studied by in vivo depletion experiments. Activation of T and natural killer cells and the induction of tumor senescence were analyzed by flow cytometry.ResultsOn immune checkpoint blockade, visible lymphomas developed at later time points than in untreated controls, indicating an enhanced tumor control. Importantly, 20% to 30% of mice were even long-term protected and did never develop clinical signs of tumor growth. The therapeutic effect was dependent on cytokine-induced senescence in malignant B cells. The proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor (TNF) were necessary for the survival benefit as well as for senescence induction in the λ-MYC model. Antibody therapy improved T-cell functions such as cytokine production, and long-time survivors were only observed in the presence of T cells. Yet, NK cells also had a pronounced effect on therapy-induced delay of tumor growth. Antibody treatment enhanced numbers, proliferation and IFN-γ expression of NK cells in developing tumors. The therapeutic effect was fully abrogated only after depletion of both, T cells and NK cells, or after ablation of either IFN-γ or TNF.ConclusionsTumor cell senescence may explain why patients responding to immune checkpoint blockade frequently show stable growth arrest of tumors rather than complete tumor regression. In the lymphoma model studied, successful therapy required both, tumor-directed T-cell responses and NK cells, which control, at least partly, tumor development through cytokine-induced tumor senescence.

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Immune Cell Profiling in CML Bone Marrow By Multiplex Immunohistochemistry

Blood ◽

10.1182/blood.v128.22.1897.1897 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1897-1897

Author(s):

Brück Oscar ◽

Sami Blom ◽

Riku Turkki ◽

Panu E Kovanen ◽

Antonio Ribeiro ◽

...

Keyword(s):

T Cells ◽

Cd8 T Cells ◽

Immune Checkpoint ◽

Cd4 T Cells ◽

Research Funding ◽

Immune Cell ◽

Checkpoint Inhibitors ◽

Cytotoxic T Cells ◽

Helper T Cells ◽

Analysis Software

Abstract Background In most solid tumors, CD8+ cytotoxic T-cells and type 1 T-helper cells are associated with a positive prognosis, but a strong immunosuppressive microenvironment may hamper their effectiveness. This notion has contributed to the development of new immune-activating therapies, such as immune checkpoint inhibitors. Although having demonstrated long-term remissions in many different solid tumor types, immune checkpoint inhibitors have not been evaluated comprehensively in hematological malignancies. In this study, we aimed to characterize the cellular and molecular immunological profiles of chronic myeloid leukemia (CML) patients' bone marrow (BM) samples. Methods BM biopsies were taken at the time of diagnosis from chronic phase CML patients (n=57) treated in the Helsinki University Hospital during years 2005-2015. We used non-leukemic (NL) BM biopsies (n=10) as controls. Using hematopathologic expertise, we constructed tissue microarray (TMA) blocks from duplicate BM spots characterized with high leukemic cell infiltration. We stained TMA slides using multiplexed immunohistochemistry (IHC) combining fluorescent and chromogenic staining allowing detection of up to six markers and nuclei simultaneously. Marker panels included T and B-lymphoid (CD3, CD4, CD8, CD20), myeloid dendritic (CD11c, BDCA-1, BDCA-3), macrophage (CD68, pSTAT1, c-MAF), natural killer cell (CD3 and CD56) and leukemia cell (CD34) markers. In addition, we examined immune checkpoint molecules (PD1, CTLA4, OX40, LAG3, TIM3) and their ligands in leukemic cells (HLA-G, PD-L1, PD-L2, HLA-ABC), as well as activation markers (CD25, CD27, CD57, Granzyme B and CD45RO). We analyzed leukemia patients' immune checkpoint expression profiles quantitatively using the image analysis software Cell Profiler and cell analysis software FlowJo and compared results with NL BMs' immune cell profiles. Results The proportion of CD3+ T cells of all cells was significantly higher in CML BM vs. NL BM (median 6.0% [interquartile range (IQR) 3.6-10.7] vs. 2.1% [IQR 1.5-4.5], p=0.001). There was no significant difference in CD8+ cytotoxic T cell levels, but CD4+ helper T cells were 8-fold more abundant in CML as compared to non-leukemic BM (p<0.0001). The proportion of both memory CD45RO+CD8+ T cells (62.2% [IQR 47.4-69.8] vs. 47.3% [IQR 27.9-56.2] of CD8+ T cells, p=0.03) and memory CD45RO+CD4+ T cells (61.8% [IQR 51.8-68.5] vs. 40.0% [IQR 25.6-57.9] of CD4+ T cells, p=0.004) were significantly higher in leukemic patients. Although the proportion of PD1+CD8+ T cells did not differ between CML and NL BM, there was a significantly lower proportion of PD1+CD4+ T cells in CML BM vs. NL BM (25.1% [IQR 17.0-38.7] vs. 69.5% [IQR 50.7-77.9], p<0.0001). However, as the number of CD4+ T cells was increased in CML, the absolute number of CD4+PD1+ T cells of total cell population was 3-fold higher in CML BM than in NL BM (p=0.02). Both the proportion of OX40+CD4+ T cells (42.3% [IQR 28.7-51.6] vs. 18.1% [IQR 13.2-22.9], p=0.001) and OX40+CD8+ T cells (42.6% [IQR 25.8-60.7] vs. 12.7% [IQR 5.0-15.8], p<0.0001) were increased in leukemic patients. Interestingly, also the proportion of OX40+PD1+CD8+ T cells (25.7% [IQR 15.4-36.4] vs. 11.9% [IQR 5.0-15.8], p=0.0019) was higher in CML samples. Conclusion Multiplex IHC allows detailed characterization of immune cell subtypes and their phenotypes in BM biopsy samples. Our data show significant heterogeneity in immune cell subsets between individual patients. The CML BM is characterized with an increase in CD3+ T cells, especially helper T cells and CD45RO+ memory T cells, when compared to non-leukemic BM. Phenotypically, OX40+PD1neg T cells and OX40+PD1+ cytotoxic T cells were elevated in CML patients. The analysis of other immune cell subclasses, including inhibitory immune cells, and the correlation of histologic findings to prognostic data are ongoing. Together, they will provide a detailed understanding of BM immune cell composition in CML. Disclosures Mustjoki: Novartis: Honoraria, Research Funding; Ariad: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding.

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