Is There a Place for Hematopoietic Stem Cell Transplantation in Rheumatology?

Remission is not maintained over 2 years with hematopoietic stem cell transplantation for rheumatoid arthritis: A systematic review with meta-analysis

BACKGROUND

Hematopoietic stem cell (HSC) transplantation (HSCT) is being accepted as a standard of care in various inflammatory diseases. The treatment of rheumatoid arthritis (RA) has been closely evolving with the understanding of disease pathogenesis. With the rising resistance to the traditional disease-modifying anti-rheumatic drugs and targeted biological therapy, researchers are in pursuit of other methods for disease management. Since the ultimate goal of the ideal treatment of RA is to restore immune tolerance, HSCT attracts much attention considering its reparative, paracrine, and anti-inflammatory effects. However, a systematic review of studies on HSCT in RA is lacking.

AIM

To investigate the role of HSCT in the management of RA.

METHODS

A detailed search of PubMed, Scopus, EMBASE, Cochrane, and the Web of Science databases was made to identify the relevant articles till September 2020 following Cochrane and PRISMA guidelines. We extracted data including the number of patients, source of hematopoietic stem cells, their mobilization and conditioning regimens, results, and complications from the eligible studies. Results were dichotomized into success (ACR 50/70) and failure (ACR 20) based on the improvement from baseline characteristics. The methodological quality of the included studies was also assessed. Analysis was performed using OpenMeta[Analysis] software.

RESULTS

We included 17 studies (1 randomized controlled trial, 11 prospective, and 5 retrospective studies) with 233 patients for analysis. HSCT provided a significantly beneficial overall improvement in the clinical grades of ACR criteria (Z = 11.309, P < 0.001). However, the remission was noted only till 24 mo and later on the significance of the result was lost (Z = 1.737, P = 0.082). A less than 1% treatment-related mortality was noted from the included studies. No major drug-related toxicities were noted in any of the included studies. All patients who underwent allogeneic HSCT received immunosuppression in the conditioning regimen to counteract the graft-vs-host reaction which made them vulnerable to infections. It is noted that the source of hematopoietic stem cells did not play a role in altering the functional outcome and both autologous (Z = 9.972, P < 0.001) and allogenic (Z = 6.978, P < 0.001) sources produced significant improvement in the outcome compared to the pre-operative state despite having a significant heterogeneity among the studies reporting them (I² = 99.4, P < 0.001).

CONCLUSION

Although the available literature is encouraging towards the use of HSCT in refractory cases with significant improvement from baseline till 2 years, the inclusion of HSCT into the standard of care of RA needs further exploration.

Novel Discoveries in Immune Dysregulation in Inborn Errors of Immunity

With the expansion of our knowledge on inborn errors of immunity (IEI), it gradually becomes clear that immune dysregulation plays an important part. In some cases, autoimmunity, hyperinflammation and lymphoproliferation are far more serious than infections. Thus, immune dysregulation has become significant in disease monitoring and treatment. In recent years, the wide application of whole-exome sequencing/whole-genome sequencing has tremendously promoted the discovery and further studies of new IEI. The number of discovered IEI is growing rapidly, followed by numerous studies of their pathogenesis and therapy. In this review, we focus on novel discovered primary immune dysregulation diseases, including deficiency of SLC7A7, CD122, DEF6, FERMT1, TGFB1, RIPK1, CD137, TET2 and SOCS1. We discuss their genetic mutation, symptoms and current therapeutic methods, and point out the gaps in this field.

Autologous stem-cell transplantation in systemic sclerosis-associated interstitial lung disease: early action in selected patients rather than escalation therapy for all

Systemic sclerosis (SSc) is a rare rheumatic disease characterised by inflammation, vasculopathy and fibrosis of skin and internal organs. A common complication and a leading cause of death in SSc is interstitial lung disease (ILD). The current armamentarium of treatments in SSc-ILD mainly includes immunosuppressive therapies and has recently been expanded with anti-fibrotic agent nintedanib. Autologous stem cell transplantation (SCT) is increasingly used in progressive diffuse cutaneous SSc. This intensive treatment has been studied in three randomised trials and demonstrated to improve survival and quality of life. In the subsets of patients with SSc-ILD, SCT resulted in stabilisation and modest improvement of lung volumes and disease extent on high resolution computed tomography, but less impact was seen on diffusion capacity. Comparison of SCT outcomes with results from SSc-ILD trials is difficult though, as lung involvement per se was not an inclusion criterion in all SCT trials. Also, baseline characteristics differed between studies. The risk of severe treatment-related complications from SCT is still considerable and patients with extensive lung disease are particularly at risk of complications during transplantation. Therefore SCT should only be provided by experienced multidisciplinary teams in carefully selected patients. Future research needs to include comprehensive pulmonary evaluation and establish whether SCT early in the disease might prevent irreversible pulmonary damage and reduce treatment-related complications. Also, more insight in mechanisms of action of SCT in the lung and predictors for response will improve the use of this treatment in SSc-ILD. In this review the role of SCT in the treatment of SSc-ILD is summarised.

Stem cell therapy in dermatology

Stem cells are precursor cells present in many tissues with ability to differentiate into various types of cells. This interesting property of plasticity can have therapeutic implications and there has been substantial research in this field in last few decades. As a result, stem cell therapy is now used as a therapeutic modality in many conditions, and has made its way in dermatology too. Stem cells can be classified on the basis of their source and differentiating capacity. In skin, they are present in the inter-follicular epidermis, hair follicle, dermis and adipose tissue, which help in maintaining normal skin homeostasis and repair and regeneration during injury. In view of their unique properties, they have been employed in treatment of several dermatoses including systemic sclerosis, systemic lupus erythematosus, scleromyxedema, alopecia, Merkel cell carcinoma, pemphigus vulgaris, psoriasis, wound healing, epidermolysis bullosa and even aesthetic medicine, with variable success. The advent of stem cell therapy has undoubtedly brought us closer to curative treatment of disorders previously considered untreatable. Nevertheless, there are multiple lacunae which need to be addressed including ideal patient selection, timing of intervention, appropriate conditioning regimens, post-intervention care and cost effectiveness. Further research in these aspects would help optimize the results of stem cell therapy.

Is biological therapy in systemic sclerosis the answer?

Systemic sclerosis is a systemic fibrosing disorder associated with significant morbidity and mortality, with no universally accepted disease-modifying therapy. Significant advances in the understanding of systemic sclerosis in recent years have guided the exploration of biological drugs in systemic sclerosis. In this narrative review, we summarize the published literature on biologic therapies in systemic sclerosis. A double-blind randomized trial, and an open label trial of tocilizumab (which antagonizes the interleukin 6 receptor), identified potential benefits in skin and lung fibrosis in systemic sclerosis; however, these differences failed to attain statistical significance. Two open-label trials compared rituximab (which depletes B lymphocytes) to conventional treatment/ cyclophosphamide in systemic sclerosis-associated interstitial lung disease (ILD), and revealed significant improvements in lung functions and skin disease with rituximab. Significant observational data also support the use of rituximab in skin, lung, muscle and joint manifestations of systemic sclerosis. Abatacept (which blocks T lymphocyte activation) has demonstrated utility for skin and joint disease in systemic sclerosis; a recent clinical trial failed to demonstrate benefits in improving skin thickness compared to placebo. Agents targeting type I interferons, interleukin 17 pathway, CD19 and plasma cells hold promise in systemic sclerosis; however, high-quality evidence is lacking. The results of different ongoing clinical trials targeting B lymphocytes, T lymphocytes, various cytokines (interleukins 6, 17, 4, 13, IL-1α), platelet-derived growth factor receptor, proteasome, integrins or oncostatin M may help guide future therapeutic regimens with biological agents in systemic sclerosis.