Abstract
Background:
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with an increased risk of graft-versus-host disease (GvHD), a strong prognostic predictor of early mortality within the first 2 years following allo-HSCT. The objective of this study was to describe the harm outcomes reported among patients receiving second- and third-line treatment as part of the management for GvHD via a systematic literature review.
Methods:
A total of 34 studies met the systematic review inclusion criteria, reporting adverse events (AEs) across 12 different second- and third-line therapies.
Results:
A total of 14 studies reported AEs across nine different therapies used in the treatment of acute GvHD (aGvHD), 17 studies reported AEs of eight different treatments for chronic GvHD (cGvHD) and 3 reported a mixed population. Infections were the AE reported most widely, followed by haematologic events and laboratory abnormalities. Reported infections per patient were lower under extracorporeal photopheresis (ECP) for aGvHD (0.267 infections per patient over 6 months) relative to any of the therapies studied (ranging from 0.853 infections per patient per 6 months under etanercept up to 1.998 infections per patient on inolimomab).
Conclusion:
The reported incidence of infectious AEs in aGvHD and grade 3–5 AEs in cGvHD was lower on ECP compared with pharmaceutical management.
Introduction
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a treatment option for many malignant and non-malignant disorders, including acute leukaemia, lymphoma and aplastic anaemia.1,2 The European Society of Blood and Marrow Transplantation (EBMT) recently published a survey reporting 17,302 allo-HSCT procedures across 655 centres in 48 countries during 2015 – an increase of 2.1% from 2014. 3 However, allo-HSCT is associated with an increased risk of graft-versus-host disease (GvHD), which occurs in approximately 30–70% of transplanted patients.4,5 This represents a potentially fatal complication; thus, GvHD is a strong prognostic predictor of early mortality within the first 2 years following allo-HSCT. 6
Approximately 40% of individuals experience acute GvHD (aGvHD) post allo-HSCT. However, this can range from 10% to 80% depending on patient-level risk factors. 1 Clinical manifestations of acute GvHD may include maculopapular rash, elevated serum bilirubin, persistent nausea or abdominal cramping/diarrhoea. By comparison, chronic GvHD (cGvHD) can affect nearly every organ or tissue in the body, 7 occurring in approximately 30–50% of allo-HSCT recipients,6,8 and may present as a cutaneous scleroderma and/or dry and ulcerated oral mucosa, potentially associated with gastrointestinal tract sclerosis. Similar to acute disease, chronic GvHD is also associated with an elevated serum bilirubin.
The clinical management of both acute and chronic GvHD is challenging due to the relatively high proportion of patients achieving sub-optimal responses on first-line corticosteroids (<50% durable response rate),9,10 and the higher mortality risk documented in steroid-refractory GvHD patients.9,11 Following first-line steroid management, there are a wide range of pharmaceutical agents currently recommended as second- or third-line treatments for aGvHD and cGvHD. Drugs available for aGvHD include interleukin-2 receptor antibodies (e.g., basiliximab, inolimomab), anti-TNF antibodies (e.g., infliximab, etanercept), serine/threonine kinases, mTOR inhibitors (e.g., sirolimus), and immunosuppressant drugs [e.g., mycophenolate mofetil (MMF)]. 12 Recommended treatment options for cGvHD are tyrosine kinase inhibitors (e.g., imatinib), mTOR inhibitors (e.g., sirolimus, everolimus), nucleoside analogue (e.g., pentostatin), anti-CD20 monoclonal antibody (rituximab) and immunosuppressant drugs (e.g., MMF).13,14 Non-pharmaceutical therapies include extracorporeal photopheresis (ECP) – an immunomodulatory therapy currently recommended as a second-line treatment in the British Committee for Standards in Haematology guidelines for both aGvHD and cGvHD.12,13 In addition, alternate therapeutic options, including mesenchymal stem cells (MSCs) infusion, have shown promise in patients with GvHD secondary to their immunomodulatory function. 15
Given the uncertainties surrounding the biological basis of both acute and chronic GvHD and the lack of consensus around a standardized treatment approach, the harm profile of available treatments is a particularly important consideration for both healthcare providers and patients when balancing the benefits and risks of competing treatment options for post-allo-HSCT GvHD. 16 Whilst ruxolitinib was approved by the United States (US) Food and Drug Administration (FDA) for steroid-refractory aGvHD in May 2019, 17 standardised recommendations on how to best implement such a diverse array of treatments remain lacking. 18 The objective of this study was to review and describe reported harm outcomes associated with second- and third-line therapies for GvHD following allo-HSCT.
Materials and methods
Search strategy and selection criteria
The systematic review protocol was developed as per Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and the PRISMA harms checklist.19,20 A systematic literature search was performed in Medline, Medline In-Process, Embase and the Cochrane Central Register of Controlled Trials (CENTRAL) on 15 December 2017. The search strategies used in each database are detailed in the Supplemental File S1. There was no restriction on publication date.
Studies were included if they satisfied the following criteria:
Patients were diagnosed with either clinician designated aGvHD or cGvHD after stem cell transplantation from any source.
Patients received any of the following interventions: ECP, basiliximab, inolimomab, etanercept, infliximab, sirolimus, MMF, sirolimus, everolimus, imatinib, pentostatin, rituximab, MSCs, methotrexate, alemtuzumab and ruxolitinib.
The study reported harms of any type.
Papers reporting randomised controlled trials (RCTs), non-randomised clinical trials, and cohort studies with prospective or retrospective design were considered for inclusion.
English language articles or those published in a range of other languages (including Chinese, Croatian, German and Spanish) were considered.
Papers reporting prophylactic use of the intervention, conference proceedings, abstracts, case reports, case series or literature reviews were excluded.
Abstract and full-text screening were conducted by two independent reviewers (R.Z. and V.V.). Inter-rater agreement was assessed via kappa statistics. 21 Disagreements were resolved by consensus.
Data extraction and quality assessment
The full-text versions of the included papers were read by a third reviewer (E.M.) who extracted and tabulated relevant data. The data extraction was verified by the second reviewer (V.V.). All included studies were reviewed for reporting causal relations between adverse effects and the treatment of interest. Studies were reviewed for the timing of adverse effects and relation to treatment dosage. Risk of bias across studies was assessed by analysing the reason for study exclusion during the screening of the full-text articles, with the main aim of assessing the extent of missing information due to selective reporting (Supplemental Table S1).
The overall quality of included studies was assessed using the Jadad scoring system. 22 The risk of individual study bias was assessed using the McMaster Quality Assessment Scale of Harms for primary studies (Supplemental File S2). 23 Future research recommendations are summarised in Supplemental File S3.
Consistent with the PRISMA harms checklist, 20 appropriate terminology and definitions were used throughout this review, with strict differentiation among the following terms: adverse drug reaction, adverse effect, adverse event, complication, harm, safety, side effect and toxicity.
The Common Toxicity Criteria (CTC) of the National Cancer Institute and World Health Organisation (WHO) Toxicity Grading Scale were used to access the severity of AEs when reported by the primary study.24,25
Statistical analyses
In studies reporting AEs for included aGvHD treatments, the standardized ratio between the number of AEs and total number of patients at risk was calculated. These were calculated separately for infections, laboratory abnormalities and serious AEs for a defined time horizon (reported follow-up time). Where data to derive the standardized ratio were unavailable, the cumulative incidence of AEs was used as a summary measure. Both approaches were combined to assess the average AE of the treatment of interest. Insufficient data was available across the aGvHD cohort to disaggregate the data by the infectious AE severity. AEs in cGvHD cohorts were summarised as the standardised ratio between the number of AEs grade 3–5 and the total number of patients at risk. Due to the large heterogeneity in patient and disease characteristics across included study populations and the non-standardized reporting of AEs, a meta-analysis was not feasible.
Results
The literature search of electronic databases generated 6772 hits, 213 of which were selected for full-text review. Following full-text review, 179 papers were excluded based on inclusion and exclusion criteria. A total of 34 studies were included (inter-reviewer agreement; kappa = 0.73). The full selection process is described in Figure 1. Of the 34 papers satisfying the inclusion criteria, 17 articles described treatment for cGvHD, 14 for aGvHD, and 3 for a mix of both sub-populations (Table 1).

PRISMA flow chart of articles included in this systematic review.
Overview of all included studies for aGvHD and cGvHD.
aGvHD, acute graft versus host disease; cGvHD, chronic graft versus host disease; CTC, common toxicity criteria of the National Cancer Institute; ECP, extra corporeal photopheresis; MMF, mycophenolate mofetil; MSC, mesenchymal stem cells; n.a., not applicable; n.r., not reported; RCT, randomised controlled trial; US, United States; WHO, World Health Organisation toxicity grading scale.
Acute graft-versus-host disease
A total of 14 studies covering 664 aGvHD patients reported AEs on therapies used in the treatment of aGvHD (Table 2). Of the nine therapies analysed, reported infections per patient were lower under ECP for aGvHD (0.267 infections per patient over 6 months) relative to any of the pharmaceutical therapies studied (ranging from 0.853 infections per patient per 6 months under etanercept up to 1.998 infections per patient on inolimomab) (Table 2). During 3 months of follow up, 1.639 infectious AEs per patient were reported for etanercept. 6 In the case of MMF, 0.375 infectious AEs were reported after 3 months of follow up. 33 Across 6 months follow up, infectious AEs per patient were reported as; 0.267 for ECP, 0.853 for etanercept, and 1.345 for infliximab.27,28,31 The cumulative incidences of severe (grade 3–5) infections for etanercept, MMF, and pentostatin were 47%, 80% and 67% respectively (9 months follow up). 30 A single study reported much lower cumulative incidences of severe infections, 32 44.5% annually for 114 patients treated with MMF. Infectious AEs per patient over 12 months of follow up were reported as 0.739 for basiliximab and 1.998 for inolimomab (Table 2).39,60
AEs in patients with aGvHD.
AEs, adverse events; aGvHD, acute graft versus host disease; CI, cumulative incidence; BSA, body surface area; EORTC, European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group; LA, Laboratory abnormalities; n.a., not applicable; n.r., not reported.
Severe laboratory abnormalities were reported in the cases of etanercept, MMF and pentostatin,29,30,32 with a 2-month cumulative incidence of 76%, 79.8/44% and 57%, respectively. These events were reported as absent for ECP, infliximab and basiliximab.27,31,39
Serious AEs leading to death were reported as 0.029 per patient for 6 months of follow up for etanercept, 28 and, for the same period, 0.134 serious AEs leading to sepsis per patient for ECP (Table 2). 27 At 1 year of follow up, serious AEs leading to death were reported as 0.174 per patient for basiliximab and 0.531 for inolimomab.39,60 In addition to the prospective studies reviewed, a retrospective cohort study was included. The study conducted a comparison of AEs among MMF, inolimomab and etanercept, reporting a hazard of bacterial infection of 2.84 and 3.26 times higher in patients treated with inolimomab and etanercept, respectively, relative to patients treated with MMF. 34 These observations were consistent with the prospective studies.
Chronic GvHD
A total of 17 studies covering 560 cGvHD patients met the inclusion criteria and reported AEs of eight different treatments for cGvHD (Table 3). The reported incidence of severe AEs in patients receiving ECP treatment for cGvHD (0.12 over 3 months; 0.480 AEs per patient annualised) was lower than that observed for either alemtuzumab (1.155 per 3 months), imatinib (upper range 1.17 per 3 months) or MMF (1.09 AEs per patient per 3 months).41,42 The event rate in patients receiving ECP was further lower relative to low-dose imatinib (200 mg) 0.59 grade 3–5 AEs per patient across 3 months (Table 3).43,44,46,47,61 However, a strong dosage related toxicity was observed across several imatinib studies. When imatinib was reduced to a dosage of 100 mg, an average of 0.26 severe AEs per patient within 6 months of follow up was observed. 46 For the same follow-up period, higher doses of imatinib (up to 300 mg) resulted in an average of 0.9 severe AEs per patient, 43 increasing to 1.17 AE per patient when the dosage is scaled up to 400 mg over 14 months of follow up. 44
AEs in patients with cGvHD.
AEs, adverse events; cGvHD, chronic graft versus host disease; LA, laboratory abnormalities; MMF, mycophenolate mofetil; n, number; n.a. not applicable; n.r., not reported.
One study reporting AEs during MMF treatment did not report treatment related AEs but rather overall AEs. 48 Thus, the 1.09 AEs per patient within 3 months of follow up likely represents a significant overestimation for MMF (Table 3). In two studies reporting pentostatin therapy, there was a higher AE rate per patient at 6 months (paediatric population) compared with that at 19 months of follow up (0.29 versus 0.69 per patient combined across both studies).50,51 In one study of patients treated with sirolimus, the number of AEs per patient was 0.53 over a 9-month follow-up period (Table 3). 56
Two studies of rituximab treatment reported a small rate of AEs per patient, from 0.14 to 0.19 per year.54,55 Those results differed from other studies where AEs per patient were 0.43 at 12 months and 0.46 at 19.5 months of follow up (Table 3).54,61
Mixed population of aGvHD and cGvHD
Three studies covering 126 patients reported a mixed study population across three different therapies: ECP, MSC and MMF. In one of these studies, AEs were reported separately for each indication (Tables 2 and 3). 59 No infusion-related toxicities attributable to MSC treatment were reported amongst the patient population. However, two studies only reported results for the combined cohort.58,57 One study reported 0.061 central line infections per patient at 6 months of follow up, and a 64% cumulative incidence of mild hypotensive events during ECP treatment. 57 The second study reported 0.499 hematologic and 0.133 gastrointestinal AEs per patient during MMF treatment, although follow-up time was not stated. 62
Discussion
Across included studies, infections were the most frequently reported AE on second- and third-line treatments for GvHD. Reported infection rates were lower under ECP management of aGvHD relative to any of the pharmaceutical treatments analysed (standardised per patient per unit of time). Severe AEs were also lower when ECP was used in cGvHD relative to other therapeutic treatments.
Furthermore, ECP treatment was associated with the lowest observed standardised incidence of both treatment-attributable infections and laboratory abnormalities. Infectious AEs per patient over 6 months for ECP (0.27) were lower than both etanercept (0.85) and infliximab (1.35) for the same period of follow up, and even lower in comparison with MMF (0.375), although this was over a relatively short 3-month follow-up period. Infusion of MSCs was also associated with a comparably low incidence of AEs attributable to infusions (0.087 per patient/8 months). Reporting of AEs per patient treated with basiliximab was not directly comparable due to the longer 12-month follow-up period. However, most infections occurred within 3–6 months following treatment.
No laboratory abnormalities were observed on either ECP, infliximab or basiliximab. The 2-month cumulative incidence of laboratory abnormalities was reported in the case of etanercept (76%), MMF (79.8/44%) and pentostatin (57%). However, those events are reported regardless of attribution to the drug, and it is not possible to assess the extent to which these incidences are attributable to the treatment or not.
ECP treatment reported the lowest average number of severe AEs per patient (0.12) in comparison with imatinib (0.59) at a low dosage, pentostatin (0.69) and MMF (1.09) over a follow-up period of 3 months. Rituximab has only long-term results reported at 12 and 19.5 months of follow up in two studies within a US population. However, results of rituximab treatment have a lower number of AEs per patient in two separate studies reporting on an Asian population (0.14 and 0.19 versus 0.43 per patient/year). However, in general, pharmacological treatments were associated with a higher observed incidence of severe AEs when compared with ECP treatment.
Whilst this review focussed specifically on AEs associated with second- and third-line management of GvHD, in clinical practice harms are balanced with potential benefits. Our findings are in line with United Kingdom (UK) and US guidelines that support the harm–benefit profile of ECP when used in the management of aGvHD.12,14 The studies included in this review show that, for both acute and chronic GvHD, ECP treatment has specific episodes of hypotension during apheresis, but they are usually asymptomatic, and laboratory anomalies were rare and mostly transient in nature.27,41,42
The evidence base quantifying AEs of interventions and therapeutics for second- and third-line treatment of aGvHD and cGvHD after allo-HSCT is limited.63,64 This systematic review of both second- and third-line treatments was designed to identify the available information in the published literature regarding aGvHD and cGvHD after allo-HSCT but does have some limitations. Being descriptive, the results presented in this review, whilst standardised, do not adjust for patient, disease or treatment factors that differ between the various populations described in the included studies that may also influence the risk of AEs. In particular, none of these descriptive comparisons were adjusted for pre-treatment with steroids. Whilst corticosteroids were out of scope of this review, the observed rates of infections on the various second-line therapies reviewed may be influenced by the duration and dosage of any prior first-line steroid management of GvHD. In addition, it could not be fully ascertained from all included studies whether patients were being treated with any of the study therapies as monotherapy or in combination. This may limit this review’s capacity to attribute any observed differences in AE rate to any one treatment. The lack of data around disease severity also makes it difficult to separate any of the observed differences in clinical outcome by therapy from variations in baseline disease severity. Furthermore, the full range of available therapies for GvHD after allo-HSCT was not captured in the included articles satisfying the inclusion criteria for this review. There was some variability in the grading of AEs across included studies. A formal meta-analysis sourcing individual patient data or key confounder aggregate data would be required to better separate treatment effects from these important sources of potential confounding. Finally, whilst the scope of this review was limited to AE reporting only, the harm profile of the therapies analysed needs to be balanced with their respective benefits for informed decision making in the clinical management of GvHD. Therapeutic burden, whilst outside the scope for our review, is also an important consideration in treatment selection. This is relevant for ECP, which requires central line placement and ongoing maintenance in addition to frequent clinic visits.
Overall, the reported incidence of infectious AEs in aGvHD and severe AEs in cGvHD was lower compared with pharmaceutical-only management. Formal statistical comparisons, including adjustment for corticosteroid pre-treatment, severity of GvHD and patient cohort heterogeneity, would be required to establish whether these observed reductions can be attributable to ECP itself.
Supplemental Material
sj-pdf-1-tah-10.1177_2040620720977039 – Supplemental material for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review
Supplemental material, sj-pdf-1-tah-10.1177_2040620720977039 for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review by Vladica M. Velickovic, Emily McIlwaine, Rongrong Zhang and Tim Spelman in Therapeutic Advances in Hematology
Supplemental Material
sj-pdf-2-tah-10.1177_2040620720977039 – Supplemental material for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review
Supplemental material, sj-pdf-2-tah-10.1177_2040620720977039 for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review by Vladica M. Velickovic, Emily McIlwaine, Rongrong Zhang and Tim Spelman in Therapeutic Advances in Hematology
Supplemental Material
sj-pdf-3-tah-10.1177_2040620720977039 – Supplemental material for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review
Supplemental material, sj-pdf-3-tah-10.1177_2040620720977039 for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review by Vladica M. Velickovic, Emily McIlwaine, Rongrong Zhang and Tim Spelman in Therapeutic Advances in Hematology
Supplemental Material
sj-pdf-4-tah-10.1177_2040620720977039 – Supplemental material for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review
Supplemental material, sj-pdf-4-tah-10.1177_2040620720977039 for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review by Vladica M. Velickovic, Emily McIlwaine, Rongrong Zhang and Tim Spelman in Therapeutic Advances in Hematology
Supplemental Material
sj-pdf-5-tah-10.1177_2040620720977039 – Supplemental material for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review
Supplemental material, sj-pdf-5-tah-10.1177_2040620720977039 for Adverse events in second- and third-line treatments for acute and chronic graft-versus-host disease: systematic review by Vladica M. Velickovic, Emily McIlwaine, Rongrong Zhang and Tim Spelman in Therapeutic Advances in Hematology
Footnotes
Author contributions
VV designed the study, ran the analysis, reviewed and interpreted the results and drafted and reviewed the manuscript.
EM designed the study, reviewed and interpreted the results and reviewed the manuscript.
RZ designed the study, reviewed and interpreted the results and reviewed the manuscript.
TS designed the study, reviewed and interpreted the results and drafted and reviewed the manuscript.
Conflict of interest statement
VV, EM, RZ, and TS are/were employees of Synergus AB – health economics and market access consulting company, which received a grant from Mallinckrodt Pharmaceuticals to perform the study. Mallinckrodt reviewed the manuscript only to verify accuracy of product mentions.
Ethical/consent statement
Our study did not require an ethical board approval because is was a systematic review of already published studies, each of which had obtained their own individual approval.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was supported with an unrestricted grant from Mallinckrodt Pharmaceuticals.
Supplemental material
Supplemental material for this article is available online.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
