Allogeneic stem cell transplantation for autoimmune diseases: nonmyeloablative conditioning regimens

Hematopoietic stem cell transplantation and cellular therapies for autoimmune diseases: overview and future considerations from the Autoimmune Diseases Working Party (ADWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Autoimmune diseases (ADs) represent a heterogenous group of complex diseases with increasing incidence in Western countries and are a major cause of morbidity. Hematopoietic stem cell transplantation (HSCT) has evolved over the last 25 years as a specific treatment for patients with severe ADs, through eradication of the pathogenic immunologic memory and profound immune renewal. HSCT for ADs is recently facing a unique developmental phase across transplant centers. This review provides a comprehensive overview of the recent evidence and developments in the area, including fundamentals of preclinical research, clinical studies in neurologic, rheumatologic and gastroenterologic diseases, which represent major indications at present, along with evidence of HSCT for rarer indications. Moreover, we describe the interwoven challenges of delivering more advanced cellular therapies, exploiting mesenchymal stem cells, regulatory T cells and potentially CAR-T cell therapies, in patients affected by ADs. Overall, we discuss past and current indications, efficacy, associated risks and benefits, and future directions of HSCT and advanced cellular therapies in the treatment of severe/refractory ADs, integrating the available literature with European Society for Blood and Marrow Transplantation (EBMT) registry data.

Hematopoietic Stem Cell Transplantation for Autoimmune Disease

The introduction of targeted biologic therapies has changed the treatment landscape for autoimmune diseases (ADs) substantially, but although these therapies provide more specificity, they require continuous administration, rarely restore organ function or reverse disability, and are not curative. Over the last 25 years, hematopoietic stem cell transplantation (HSCT) has been increasingly used to treat patients in whom the risk:benefit ratio of HSCT is acceptable. In contrast to chronic suppression of immune function, this intensive one-off procedure aims to provide treatment-free remissions by the reinduction of self-tolerance. The European Society for Blood and Marrow Transplantation (EBMT) Autoimmune Diseases Working Party (ADWP) has been central to development of this approach, with over 3,300 HSCT registrations for ADs. Recent data have improved the evidence base to support autologous HSCT in multiple sclerosis, systemic sclerosis, and Crohn's disease, along with a wide range of rarer disease indications, and autologous HSCT has become an integral part of treatment algorithms in various ADs.

Allogeneic HSCT for Autoimmune Diseases: A Retrospective Study From the EBMT ADWP, IEWP, and PDWP Working Parties

Background: This retrospective study assessed the use and long-term outcome of allogeneic hematopoietic stem cell transplantation (HSCT) in patients with severe autoimmune diseases (ADs), reported to the European Society for Blood and Marrow Transplantation (EBMT) registry.

Methods: Between 1997 and 2014, 128 patients received allogeneic HSCT for various hematological (n = 49) and non-hematological (n = 79) refractory ADs. The median age was 12.7 years (0.2–62.2). Donors were syngeneic for seven, matched related for 46, unrelated for 51, haploidentical for 15, and cord blood for nine patients.

Results: The incidence of grades II-IV acute graft-vs.-host disease (GvHD) was 20.8% at 100 days. Cumulative incidence of chronic GvHD was 27.8% at 5-years. Non-relapse mortality (NRM) was 12.7% at 100-days. Overall survival (OS) and Progression-Free Survival (PFS) were 70.2 and 59.4% at 5-years, respectively. By multivariate analysis, age <18 years, males, and more recent year of transplant were found to be significantly associated with improved PFS. Reduced conditioning intensity was associated with a lower NRM. On a subgroup of 64 patients with detailed information a complete clinical response was obtained in 67% of patients at 1-year.

Conclusions: This large EBMT survey suggests the potential of allogeneic HSCT to induce long-term disease control in a large proportion of refractory ADs, with acceptable toxicities and NRM, especially in younger patients.

[Use of mesenchymal stem cells in the combination therapy of ulcerative colitis]

AIM

To compare results of treatment in patients with moderate and severe ulcerative colitis (UC), receiving standart anti-inflammatory therapy (second group) and its combination with bone marrow-derived mesenchymal stromal cells (MSC) (first group).

RESULTS

Complex therapy of UC acute flare-up, including MSC did not influence on reccurence frequency, remission duration and mean value of clinical and endoscopic activity indices during 1 year of follow-up: in 1 group UC flare-up occurred in 2 (16.7%) patients, in 2 group--in 3 patients (30%). RR was 0.3 (95% CI 0/08--1.36; p=0.2; x2=1.47). After 2 years of follow-up risk of UC exacerbation in 1 group was 3 times lower than in the 2 group (p=0.03). Mean duration of remission in the 1 group was 22 months, in the 2 group--17 months (p=0.049). After 3 years of follow-up remission duration in the 1 and 2 groups were 22 and 22 months, respectively (p=0.66). Activity Index according to Rachmilevich in the 1 group was 4.75+/-1.13 points, in the 2--8.1+/-1.1 points (p=0.001).

CONCLUSION

MSC application increases efficacy of anti-inflammatory treatment in patients with acute exacerbation of UC.

Cell therapy of refractory Crohn's disease

We analyzed medium-term efficiency and safety of biological therapy of Crohn's disease, in particular transplantation of allogenic mesenchymal stromal bone marrow cells and anticytokine therapy with selective immunosuppressive agents. It was found that both methods of biological therapy of refractory Crohn's disease resulted in clinical and in some cases endoscopic remission. In most cases, clinical remission was maintained without steroid hormone therapy. Thus, both methods produce comparable clinical results. It was concluded that transplantation of mesenchymal stromal bone marrow cells could be considered as a promising method in the therapy of refractory Crohn's disease comparable by its efficiency with infliximab therapy.

[Hematopoietic stem cell transplantation in systemic autoimmune diseases. State of the art]

The use of stem cell transplantation for severe autoimmune diseases refractory to conventional therapy arose from two discoveries: the excellent results of animal experiments, and serendipitous observations in human coincidental diseases. Experimental data and early phase I-II trials in highly selected patients suggest that highdose chemotherapy followed by autologous hematopoietic stem cell transplantation can arrest progression of severe autoimmune diseases with an acceptable risk/benefit ratio. The present article reviews the phase II-III prospective, multicenter, randomized trials that have been performed in distinct autoimmunediseases. In addition, allogeneic stem cell transplantation for autoimmune diseases is being cautiously explored in current protocols.

Reduced-intensity allogeneic stem cell transplantation in adults and children with malignant and nonmalignant diseases: end of the beginning and future challenges

During the last 10 years, multiple studies using reduced-intensity (RI) conditioning followed by allogeneic stem cell transplantation (AlloSCT) have been reported in adult and, less so, pediatric recipients. RI AlloSCT allegedly eradicates malignant cells through a graft-versus-leukemia/graft-versus-tumor effect provided by alloreactive donor T lymphocytes, natural killer cells, or both. Various studies have clearly demonstrated a graft-versus-leukemia/graft-versus-tumor effect in hematologic malignancies and solid tumors. Acute short-term toxicity, including infection and organ decompensation after myeloablative conditioning therapy, can result in a significant incidence of early transplant-related mortality. More importantly, long-term late effects-including growth retardation, infertility, and secondary malignancies-are major complications after myeloablative conditioning therapy, especially in vulnerable children, who are more susceptible to these complications. Recent results comparing RI conditioning with myeloablative conditioning followed by HLA-matched sibling AlloSCT have demonstrated a significant reduction in use of blood products, risk of infections, transplant-related mortality, length of hospitalization, and feasibility of conditioning therapy in outpatient settings. Despite the success of RI AlloSCT, large prospective randomized multicenter studies are necessary to define the appropriate patient population, optimal conditioning regimens and pretransplantation immunosuppression, role of donor lymphocyte infusions, duration of hospitalization, overall survival, cost-benefit ratio, and differences in long-term effects to evaluate the role of RI AlloSCT more fully. We review the recent experience of RI AlloSCT in adults and children with both malignant and nonmalignant diseases and discuss the challenges for the future.

Reduced-intensity allogeneic hematopoietic stem cell transplantation for acute leukemias: ‘what is the best recipe?’

Reduced-intensity stem cell transplantation (RIST) has been shown to be a safe and useful alternative transplant method for patients including elderly and medically unfit patients. RIST conditioning regimens vary widely in the intensity of myeloablation, immunoablation, and antileukemia effects, and thus optimal regimen for each disease entity is yet to be determined. Most reports on RIST to date are small, single-institution experiences or retrospective studies with heterogeneous patient populations and primary diseases, complicating any direct comparison between studies. In acute myeloid leukemia (AML), moderate-intensity regimens may be effective, achieving 30-70% 1-year disease-free survival in various series, but minimal-intensity regimens are associated with high relapse rates. In acute lymphoblastic leukemia (ALL), not even moderate-intensity regimens are effective and most patients with advanced ALL relapse post transplant. Thus, the risk/benefit ratios of graft-versus-host disease/graft-versus-leukemia effect differ among diseases. Larger, prospective, multi-center clinical trials are needed to determine the best use of RIST in hematologic malignancies.

Stem cell transplantation in autoimmune diseases: an update

Immunosuppressive or immunomodulatory treatments are often used in patients with various autoimmune diseases (AID). However, since conventional treatments are rarely curative, alternative treatment methods have been looked for. Based on animal experiments and anecdotal case reports, stem cell transplantation (SCT) has received considerable attention in the treatment of severe autoimmune diseases during the last decade. This review summarizes current experience of SCT in patients this field. Although early experience shows some promise, randomized studies are necessary to evaluate the real value of autologous SCT in various autoimmune diseases. Since autologous SCT may not be curative in patients with AID, also evaluation of allogeneic SCT is important in the future.

Haematopoietic stem cell transplantation for autoimmune disorders: the American perspective

The hypothesis that haematopoietic stem cell transplantation (HSCT) might be useful in treating refractory autoimmune diseases (AID) was suggested by studies in animal models and by the improvement of concurrent autoimmune diseases in patients who had undergone transplantation for haematological disorders. This concept has now been tested in a substantial number of phase I/II clinical trials of autologous HSCT. These early results are promising, even in patients who have failed on multiple standard therapies for AID. Transplantation-related toxicity has decreased with growing experience in the application of this procedure, better patient selection and the modification of treatment protocols. Randomized trials currently under way or under consideration should clarify the role of HSCT in patients with autoimmune disorders.

Rheumatoid arthritis

Haematopoietic stem cell transplantation (HSCT) is now being investigated as a potential therapy for patients with severe refractory rheumatoid arthritis unresponsive to conventional therapies, including tumour necrosis factor-alpha blockade. Pilot studies and an analysis of worldwide cases included in the European Group for Blood and Marrow Transplantation/Autologous Blood and Marrow Transplant Registry registry have enabled the progression of the technique. HSCT is well tolerated in patients with rheumatoid arthritis, and there has been no transplant-related mortality. Although HSCT is not a cure, an improved response to previously ineffective therapies is often seen. Further research is, however, required, and this procedure is still considered appropriate only for those patients for whom there is no reasonable therapeutic alternative. This paper reviews all the previous data relating to HSCT in rheumatoid arthritis, outlines the current stand and discusses future protocol options and research.

Rituximab in autoimmune diseases

Modern treatments of autoimmune diseases are based on immunological therapies. Rituximab induces a targeted B-cell depletion in the aim of eradicating autoreactive clones in various autoimmune disorders. Several studies are being undertaken and preliminary reports are very encouraging. The mechanism of action is not evident, but appears to be connected with the lowering of autoantibody levels, in the diseases where relevant antibody titres are relievable. Most of the patients treated were affected by idiopathic thrombocytopenic purpura (ITP) and autoimmune haemolytic anaemia, but also very rare diseases like acquired haemophilia are reported. Best results are described in autoimmune haemolytic anaemia, in many others there is clear evidence for efficacy; in all the diseases the number of complete or partial remission, though temporary, is much greater than 50%. Side effects are rarely reported, and immunosuppression is not a great problem. The persistence of clinical improvement for more than 1 year after B-lymphocyte repopulation supports the hypothesis of a stochastic generation of pathogenic B-cell subsets. Other studies and controlled trials are required to establish when and which patients are to be treated, and find the opportunity of the association of others drugs.

Significance of chimerism in hematopoietic stem cell transplantation: new variations on an old theme

The main goal of post-transplantation monitoring in hematopoietic stem cell transplantation (HSCT) is to predict negative events, such as disease relapse, graft rejection and graft-versus-host disease, in order to intervene with appropriate therapy. In this context, chimerism analysis is an important method in monitoring post HSCT outcome. Mixed chimerism (MC) is mainly evaluated to define engraftment and relapse. Detection of MC is a prerequisite in both myeloablative and nonmyeloablative HSCT, in order to assess the graft status and decide later therapeutic strategies such as donor lymphocyte infusion. In this review, we discuss various techniques including erythrocyte phenotyping, cytogenetic analysis, fluorescent in situ hybridization, restriction fragment length polymorphism, STR/VNTR analysis and real-time quantitative PCR, along with the various methods used to detect minimal residual disease (MRD) in different diseases such as chronic myeloid leukemia, acute myelomonocytic leukemia or acute lymphoblastic leukemia. The review mainly highlights the optimal methodological approach, which needs to be informative, sensitive and quantitatively accurate for MC detection. Future of post HSCT graft monitoring lies in the selection of the most accurate and sensitive technique to determine both MC and MRD. Such an approach would be helpful in not only determining relapse or rejection, but also in ascertaining various responses to different treatment modalities.