Veno-occlusive Disease in HSCT Patients: Consensus-based Recommendations for Risk Assessment, Diagnosis, and Management by the GITMO Group

Variation in clinical practice affects veno-occlusive disease management, mainly in patients who undergo allogeneic hematopoietic stem cell transplantation. Disputes about diagnostic criteria, treatment, and prophylaxis, due to the lack of high-quality data, are at the base of this variability. With the aim of limiting inconsistency in clinical care, thus improving both patient outcomes and data collection reliability, the Italian Society of Stem cell transplant (Gruppo Italiano Trapianto Midollo Osseo e Terapia Cellulare) launched a collaborative effort to formulate recommendations based on integration of available evidence and expert's consensus. A systematic method, according to US National Institute of Health guidelines and Italian National System for Guidelines, was used. Twenty-nine recommendations were approved with a strong (20) or weak (9) level of agreement, while 26 were rejected. In particular, the panel pointed out the need to achieve an early diagnosis, encouraging the adoption of European Society for Blood and Marrow Transplantation criteria and the prompt use of ultrasonography. Moreover, our experts strongly recommended in favor of prophylactic use of ursodeoxycholic acid. As soon as a veno-occlusive disease diagnosis is established, treatment with defibrotide should be started for at least 21 days. A number of areas of uncertainty, particularly concerning risk stratification and use of diagnostic tools such as elastography has been identified and discussed.

Effect of Sirolimus levels between days 11 and 20 after allogeneic stem cell transplantation on the risk of hepatic sinusoidal obstruction syndrome

Sinusoidal obstruction syndrome (SOS) is a serious complication of hematopoietic stem cell transplantation (HSCT). Sirolimus plus tacrolimus is an accepted regimen for graft-versus-host disease (GVHD) prophylaxis, with both agents implicated as risk factors for SOS. We analyzed 260 consecutive patients who underwent allogeneic HSCT following myeloablative conditioning using total body irradiation (TBI)-based (n = 151) or chemotherapy only (n = 109) regimens, with sirolimus plus tacrolimus for GVHD prophylaxis. SOS occurred in 28 patients at a median of 22 (range, 12-58) days. Mean sirolimus trough levels were higher between days 11 and 20 following transplant in patients who developed SOS (10.3 vs. 8.5 ng/ml, P = 0.008), with no significant difference in mean trough levels between days 0 and 10 (P = 0.67) and days 21-30 (P = 0.37). No differences in mean tacrolimus trough levels during the same time intervals were observed between those developing SOS and others. On multivariable analysis, a mean sirolimus trough level ≥ 9 ng/ml between days 11 and 20 increased the risk of SOS (hazard ratio 3.68, 95% CI: 1.57-8.67, P = 0.003), together with a longer time from diagnosis to transplant (P = 0.004) and use of TBI (P = 0.006). Our results suggest that mean trough sirolimus levels ≥ 9 ng/mL between days 11 and 20 post transplant may increase the risk of SOS and should be avoided.

Uniform graft-versus-host disease prophylaxis with posttransplant cyclophosphamide, sirolimus, and mycophenolate mofetil following hematopoietic stem cell transplantation from haploidentical, matched sibling and unrelated donors

Following the success of posttransplant cyclophosphamide (PT-CY) as graft-versus-host disease (GVHD) prophylaxis in haploidentical transplantation, this prevention strategy has progressively been used for allogeneic hematopoietic stem cell transplantation (allo-HSCT) from HLA-matched sibling (MSD) and unrelated donor (MUD). We have introduced PT-CY plus sirolimus and micophenolate mofetil (PT-CY-Sir-MMF) as GVHD prophylaxis in allo-HSCT, irrespective of donor type. This study reports on the safety and efficacy of PT-CY-Sir-MMF in 158 consecutive allo-HSCT from MSD (n = 52), MUD (n = 64), and haploidentical (n = 42) donor. Median age was 53 years and 66% had acute leukemia or myelodysplastic syndrome. Cumulative incidences of acute GHVD grade II-IV, III-IV and moderate to severe cGVHD were 27%, 9% and 27%, respectively. The incidence of hepatic sinusoidal obstruction syndrome was 9.5%. The 1-year cumulative incidence of non-relapse mortality, relapse and event-free survival were 14%, 12% and 75%, respectively. Compared with MSD and MUD, haploidentical transplantation had a higher incidence of CMV DNAemia requiring therapy (34% vs 35% and 52%, respectively, p = 0.04) and was a risk factor for grade III-IV acute GVHD (RR 2.8, p = 0.05). Our study shows that PT-CY-Sir-MMF is not only feasible and effective in preventing GVHD after haploidentical HSCT, but also in allo-HSCT from MSD and MUD.

Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics of Immunosuppressants in Allogeneic Hematopoietic Cell Transplantation: Part II

Part I of this article included a pertinent review of allogeneic hematopoietic cell transplantation (alloHCT), the role of postgraft immunosuppression in alloHCT, and the pharmacokinetics, pharmacodynamics, and pharmacogenomics of the calcineurin inhibitors and methotrexate. In this article (Part II), we review the pharmacokinetics, pharmacodynamics, and pharmacogenomics of mycophenolic acid (MPA), sirolimus, and the antithymocyte globulins (ATG). We then discuss target concentration intervention (TCI) of these postgraft immunosuppressants in alloHCT patients, with a focus on current evidence for TCI and on how TCI may improve clinical management in these patients. Currently, TCI using trough concentrations is conducted for sirolimus in alloHCT patients. Several studies demonstrate that MPA plasma exposure is associated with clinical outcomes, with an increasing number of alloHCT patients needing TCI of MPA. Compared with MPA, there are fewer pharmacokinetic/dynamic studies of rabbit ATG and horse ATG in alloHCT patients. Future pharmacokinetic/dynamic research of postgraft immunosuppressants should include '-omics'-based tools: pharmacogenomics may be used to gain an improved understanding of the covariates influencing pharmacokinetics as well as proteomics and metabolomics as novel methods to elucidate pharmacodynamic responses.

Terminal hepatic venule injury in liver biopsies of allogeneic haematopoietic stem cell recipients-a study of 63 cases

AIMS

Subtle lesions of terminal hepatic venules (THVs) may be overlooked in liver biopsies from haematopoietic stem cell transplant (HSCT) receipients when graft-versus-host disease is the clinical concern. The aim of this study was to evaluate the frequency of THV injury resembling sinusoidal obstruction syndrome (SOS).

METHODS AND RESULTS

Sixty-three consecutive biopsies from allogeneic HSCT recipients were scored for injured THVs. Forty-nine (78%) biopsies had injured THVs, and 10 (16%) were diagnosed with SOS (mean ± standard deviation of injured THVs/biopsy: 90 ± 9%). Biopsies diagnosed with other diseases also had injured THVs (36 ± 33%). Biopsies from patients with cyclophosphamide plus fractionated total body irradiation conditioning and biopsies taken within 100 days post-HSCT had significantly more occluded THVs (respectively: 40 ± 38%, P = 0.0188; and 35 ± 35%, P = 0.0076) than those with other conditioning regimens or in biopsies taken >100 days post-HSCT. All biopsies taken at any time in the 6-year post-HSCT period had similar amounts of THV phlebosclerosis (23 ± 25%).

CONCLUSIONS

Our results demonstrate a high incidence of THV injuries resembling SOS in post-HSCT liver biopsies. THV injuries were detectable for several years post-HSCT, and were concurrent with other diagnoses. Our results also suggest that SOS may be underdiagnosed.

Calcineurin inhibitor--free graft-versus-host disease prophylaxis with post-transplantation cyclophosphamide and brief-course sirolimus following reduced-intensity peripheral blood stem cell transplantation

Calcineurin inhibitors (CNIs) form the foundation of current graft-versus-host disease (GVHD) prophylaxis regimens. We hypothesized that a CNI-free regimen consisting of post-transplantation cyclophosphamide (PTCy) and brief-course sirolimus would reduce chronic GVHD and nonrelapse mortality (NRM) after reduced-intensity conditioning allogeneic peripheral blood stem cell transplantation (PBSCT). Twenty-six patients (median age, 61 years) underwent unmanipulated PBSCT from an 8/8 locus-matched donor (matched related donor, n = 17; natched unrelated donor, n = 9). GVHD prophylaxis consisted of PTCy and brief-course sirolimus. Donor engraftment occurred in all patients. The cumulative incidence (CI) of grade II-IV acute GVHD, grade III-IV acute GVHD, and chronic GVHD was 46%, 15%, and 31% respectively. One-year NRM was 4%. The median time to immunosuppression discontinuation was day +138. With a median follow-up of 20 months, the estimated 2-year overall survival was 71%, estimated disease-free survival was 64%, and estimated relapse incidence was 32%. In patients with a lymphoid malignancy (eg, chronic lymphoblastic leukemia, non-Hodgkin lymphoma, Hodgkin disease), 2-year disease-free survival was 100%, and there were no relapses. Good immune reconstitution was evidenced by low cytomegalovirus reactivation rate of 21% (4 of 19 at-risk patients). GVHD prophylaxis with PTCy and sirolimus achieves consistent donor engraftment, low rates of chronic GVHD and NRM, and excellent outcomes in recipients of HLA-identical related and unrelated donor allogeneic PBSCT.