AB0029 INHIBITION OF EFFECTOR B CELLS BY IBRUTINIB IN SYSTEMIC SCLEROSIS

Background:

Systemic sclerosis (SSc) is a connective tissue disease with significant morbidity and mortality. Effective treatment is still missing, and clinical control of the disease remains challenging. In particular, the development of pulmonary and cardiac fibrosis and pulmonary hypertension are severe complications responsible for excessive mortality. Currently available treatment strategies – besides aggressive autologous stem cell transplantation which is an option only for selected patients – only alleviate symptoms and slow disease progression. Previous attempts of immunomodulating therapies addressing B cell pathology like rituximab and tocilizumab in SSc showed mixed efficacy1,2

Objectives:

Here, we investigated the therapeutic potential of ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor used in B cell malignancies, to alter B cell pathology in SSc in anin vitromodel of autoimmunity.

Methods:

PBMCs and sorted B cells of 24 patients with SSc were used for functional testing after stimulation with hypomethylated DNA fragments (CpG) to induce an innate immune response. The effects of ibrutinib on cytokine production, autoantibody release and activation of the transcription factor NFκB were evaluated via multiplex cytokine assay, ELISA and flow cytometry.

Results:

Ibrutinib was able to reduce the production of the profibrotic hallmark cytokines IL-6 and TNF-α, which are mainly released by the effector B cell population, in response to TLR9-stimulation. Importantly, small doses of ibrutinib (0.1 µM) preserved the production of immunoregulatory IL-10 and IFN-γ while effectively inhibiting the cardinal cytokines of hyperactivated profibrotic effector B cells in SSc. Intracellular cytokine staining of IL-6 in B cell subsets further endorsed the potential of ibrutinib to inhibit B cells in a subset-specific manner, reducing IL-6+naïve B cells significantly but not IL-6+memory B cells. The subset specificity was abolished when high doses of ibrutinib (10 µM) were applied. In a flow cytometry analysis of phosphorylated NFκB, an important transcription factor in the induction of innate immune responses in B cells, significantly less activation was observed with ibrutinib treatment (0.1 µM). Higher doses of ibrutinib were unable to further reduce the abundance of pNFκB.

Conclusion:

Our data could pave the avenue for a clinical application of ibrutinib for patients with SSc as a novel treatment option for the underlying pathogenetic immune imbalance contributing to disease onset and progression.

References:

[1]Khanna, D.et al.Efficacy and Safety of Tocilizumab for the Treatment of Systemic Sclerosis: Results from a Phase 3 Randomized Controlled Trial [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10).

[2]Jordan, S.et al.Effects and safety of rituximab in systemic sclerosis: an analysis from the European Scleroderma Trial and Research (EUSTAR) group.Ann. Rheum. Dis.74, 1188–1194 (2015).

Disclosure of Interests:

Jakob Einhaus: None declared, Ann-Christin Pecher: None declared, Elisa Asteriti: None declared, Hannes Schmid: None declared, Kathy-Ann Secker: None declared, Silke Duerr-Stoerzer: None declared, Hildegard Keppeler: None declared, Reinhild Klein: None declared, Corina Schneidawind: None declared, Jörg Henes Grant/research support from: Novartis, Roche-Chugai, Consultant of: Novartis, Roche, Celgene, Pfizer, Abbvie, Sanofi, Boehringer-Ingelheim,, Dominik Schneidawind: None declared

Retrospective single center analysis of outcome, risk factors and therapy in steroid refractory graft-versus-host disease after allogeneic hematopoietic cell transplantation

Acute and chronic graft-vs.-host disease (aGvHD and cGvHD) are major complications after allogeneic hematopoietic cell transplantation (HCT) leading to substantial morbidity and mortality. This retrospective single-center study analyzes incidence, therapy, and outcome of GvHD in n = 721 patients ≥18 years having received allogeneic HCT 2004-2013 with a special focus on steroid refractory GvHD. Acute (n = 355/49.2%) and chronic (n = 269/37.3%) GvHD were mainly treated by steroids in first-line therapy. The proportion of steroid refractory aGvHD and cGvHD was 35.7% and 31.4%, respectively. As there is no standard therapy for steroid refractory GvHD, a range of different agents was used. In aGvHD, the overall response rate (ORR) of steroid refractory GvHD to second-line treatment was 27.4%. Mycophenolate mofetil (MMF) and mTOR inhibitors led to superior response rates (ORR 50.0% and 53.3%, respectively). In steroid refractory cGvHD therapy, ORR was 44.4%. Use of calcineurin inhibitors (CNI; n = 11/45.5%), MMF (n = 18/50.0%), mTOR inhibitors (n = 10/60.0%), and extracorporeal photophoresis (ECP; n = 16/56.3%) showed ORR above average. Targeted therapies lead to responses in 7.7% (n = 13). This data may help to improve the design of future prospective clinical studies in GvHD.

Allogeneic hematopoietic cell transplantation in patients with acute myeloid leukemia and pulmonary mucormycosis

Mucormycosis is a serious invasive fungal infection in immunocompromised patients. Patients undergoing treatment for hematologic malignancies are predominantly prone to the pulmonary manifestation of mucormycosis. Historically, allogeneic hematopoietic cell transplantation (HCT) in patients suffering from pulmonary mucormycosis (PM) was considered contraindicated owing to mortality rates up to 90%. We present 3 patients with acute myeloid leukemia and PM who were treated with radical surgical debridement combined with high-dose liposomal amphotericin B (LAB), and subsequently underwent successful allogeneic HCT. To date, all 3 patients are in complete remission and show no signs of mucormycosis. Allogeneic HCT in patients with PM seems feasible provided that the infectious focus is completely removed surgically and adequate antifungal pharmacotherapy, such as high-dose LAB or posaconazole, is established.

[Allogeneic stem cell transplantation for acute myeloid leukemia and HIV infection--case 3/2012]

HISTORY AND ADMISSION FINDINGS

A 27-year-old male patient with a past medical history of HIV presented with acute myeloid leukemia for allogeneic hematopoietic stem cell transplantation (HSCT). Highly active anti-retroviral therapy suppressed the viral load below detection threshold.

INVESTIGATIONS

There were no contraindications for allogeneic HSCT.

TREATMENT AND COURSE

Myeloablative conditioning consisted of total body irradiation and cyclophosphamide. Anti-thymocyte globulin, tacrolimus and mycophenolate mofetil were used for immunosuppression. Combined anti-retroviral therapy (nucleoside and nucleotide analog reverse-transcriptase inhibitor, boostered protease inhibitor, maraviroc and raltegravir) was maintained for allogeneic HSCT and viral load remained below detection threshold. No graft-versus-host disease or serious infectious complications occurred. The patient showed good graft function with stable hematopoiesis. Localized Kaposi's sarcoma was diagnosed six months after allogeneic HSCT and treated successfully with surgical excision and reduction of immunosuppression. Almost one year after allogeneic HSCT, the CD4+ cell count is rising and viral load remains below detection threshold with combined anti-retroviral therapy.

CONCLUSION

Allogeneic HSCT can be safely performed in HIV positive patients. Kaposi's sarcoma is a rare event after allogeneic HSCT and linked to strong immunosuppression.