Splenic irradiation as a component of a reduced-intensity conditioning regimen for hematopoietic stem cell transplantation in myelofibrosis with massive splenomegaly

Management of adult patients with CMML undergoing allo-HCT: recommendations from the EBMT PH&G Committee

ABSTRACT

Chronic myelomonocytic leukemia (CMML) is a heterogeneous disease presenting with either myeloproliferative or myelodysplastic features. Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only potentially curative option, but the inherent toxicity of this procedure makes the decision to proceed to allo-HCT challenging, particularly because patients with CMML are mostly older and comorbid. Therefore, the decision between a nonintensive treatment approach and allo-HCT represents a delicate balance, especially because prospective randomized studies are lacking and retrospective data in the literature are conflicting. International consensus on the selection of patients and the ideal timing of allo-HCT, specifically in CMML, could not be reached in international recommendations published 6 years ago. Since then, new, CMML-specific data have been published. The European Society for Blood and Marrow Transplantation (EBMT) Practice Harmonization and Guidelines (PH&G) Committee assembled a panel of experts in the field to provide the first best practice recommendations on the role of allo-HCT specifically in CMML. Recommendations were based on the results of an international survey, a comprehensive review of the literature, and expert opinions on the subject, after structured discussion and circulation of recommendations. Algorithms for patient selection, timing of allo-HCT during the course of the disease, pretransplant strategies, allo-HCT modality, as well as posttransplant management for patients with CMML were outlined. The keynote message is, that once a patient has been identified as a transplant candidate, upfront transplantation without prior disease-modifying treatment is preferred to maximize chances of reaching allo-HCT whenever possible, irrespective of bone marrow blast counts.

Splenomegaly in patients with primary or secondary myelofibrosis who are candidates for allogeneic hematopoietic cell transplantation: a Position Paper on behalf of the Chronic Malignancies Working Party of the EBMT

Splenomegaly is a hallmark of myelofibrosis, a debilitating haematological malignancy for which the only curative option is allogeneic haematopoietic cell transplantation (HCT). Considerable splenic enlargement might be associated with a higher risk of delayed engraftment and graft failure, increased non-relapse mortality, and worse overall survival after HCT as compared with patients without significantly enlarged splenomegaly. Currently, there are no standardised guidelines to assist transplantation physicians in deciding optimal management of splenomegaly before HCT. Therefore, the aim of this Position Paper is to offer a shared position statement on this issue. An international group of haematologists, transplantation physicians, gastroenterologists, surgeons, radiotherapists, and radiologists with experience in the treatment of myelofibrosis contributed to this Position Paper. The key issues addressed by this group included the assessment, prevalence, and clinical significance of splenomegaly, and the need for a therapeutic intervention before HCT for the control of splenomegaly. Specific scenarios, including splanchnic vein thrombosis and COVID-19, are also discussed. All patients with myelofibrosis must have their spleen size assessed before allogeneic HCT. Myelofibrosis patients with splenomegaly measuring 5 cm and larger, particularly when exceeding 15 cm below the left costal margin, or with splenomegaly-related symptoms, could benefit from treatment with the aim of reducing the spleen size before HCT. In the absence of, or loss of, response, patients with increasing spleen size should be evaluated for second-line options, depending on availability, patient fitness, and centre experience. Splanchnic vein thrombosis is not an absolute contraindication for HCT, but a multidisciplinary approach is warranted. Finally, prevention and treatment of COVID-19 should adhere to standard recommendations for immunocompromised patients.

Successful haploidentical hematopoietic stem cell transplantation (HSCT) and durable engraftment by repeated donor lymphocyte infusions for a Chinese patient with transfusion-dependent hemoglobin (Hb) Hammersmith and massive splenomegaly

BACKGROUND

Hemoglobin (Hb) Hammersmith is a rare form of unstable β-chain hemoglobinopathy causing hemolytic anemia. This rare event led to a more serious transfusion-dependent phenotype in a patient. It was successfully cured by haploidentical hematopoietic stem cell transplantation (HSCT).

METHODS AND RESULTS

A 9-year-old mainland Chinese male with a history of neonatal unconjugated hyperbilirubinemia was diagnosed to have hemoglobin (Hb) Hammersmith. He required regular blood transfusion but was unable to be transfused to desired parameters for 8 years prior to transplant due to social and geographical reasons. He subsequently developed marrow hyperplasia and progressive splenomegaly (down to umbilicus level), suggestive of extramedullary hematopoiesis. Eventually, the family came to Hong Kong and complied to a more intensive transfusion regimen and preconditioning chemotherapy 3 months prior to transplant. He underwent haploidentical HSCT using paternal TCRαβ/CD45RA-depleted graft but suffered from graft rejection, despite splenic irradiation for massive splenomegaly. It was successfully salvaged with second HSCT with unmanipulated graft from the same donor with additional serotherapy and donor lymphocyte infusions.

CONCLUSION

Allogenic haploidentical HSCT for hemoglobin Hammersmith is feasible but adequate immunosuppression during conditioning is crucial. Precise adoptive cell therapy can promote durable engraftment.

Pre-transplant Splenic Irradiation in Patients with Myeloproliferative Neoplasms

Purpose

Allogeneic hematopoietic cell transplantation (HCT) serves as the only curative treatment option for patients with myelofibrosis and other myeloproliferative neoplasms. Splenomegaly commonly manifests in patients with myeloproliferative neoplasms and can lead to delayed or poor engraftment, increased transfusion burden, and worse survival. Methods to decrease the effect of splenomegaly include splenectomy and splenic irradiation. We sought to report on clinical outcomes for patients treated with splenic irradiation as part of their transplant conditioning.

Methods and Materials

Patients with splenomegaly measuring greater than 22 cm were referred for splenic irradiation. They received radiation to the entire spleen to 10 Gy in 5 fractions using 3-dimensional conformal radiation with anteroposterior/posteroanterior or opposed tangent fields. Blood counts were monitored closely on treatment. Changes in splenic size were measured using first and last treatment image guided radiation therapy and pre- and posttransplant diagnostic imaging.

Results

Seventeen patients completed pretransplant splenic irradiation between 2012 and 2021. Median platelet, white blood cell, and hemoglobin levels decreased on treatment. One patient required platelet transfusion and 3 required packed red blood cell transfusions. Mean decrease in spleen size during radiation was -8.5% in the craniocaudal dimension. Prolonged decreases, measured 2 to 12 months after transplant, averaged 14.64%. All patients engrafted. Fourteen (82.4%) were alive at time of analysis with median follow-up of 4.2 years from hematopoietic cell transplantation.

Conclusions

Splenic irradiation offers a safe method of managing significant splenomegaly as part of transplant conditioning. Transplant outcomes in this series were excellent. Prospective data may be beneficial to determine the absolute benefit of this addition to pretransplant conditioning in this patient population.

Impact of spleen size and splenectomy on outcomes of allogeneic hematopoietic cell transplantation for myelofibrosis: A retrospective analysis by the chronic malignancies working party on behalf of European society for blood and marrow transplantation (EBMT)

The role of spleen size and splenectomy for the prediction of post-allogeneic hematopoietic stem cell transplant (allo-HCT) outcome in myelofibrosis remains under debate. In EBMT registry, we identified a cohort of 1195 myelofibrosis patients transplanted between 2000-2017 after either fludarabine-busulfan or fludarabine-melphalan regimens. Overall, splenectomy was performed in 202 (16.9%) patients and its use decreased over time (28.3% in 2000-2009 vs 14.1% in 2010-2017 period). By multivariate analysis, splenectomy was associated with less NRM (HR 0.64, 95% CI 0.44-0.93, P = .018) but increased risk of relapse (HR 1.43, 95% CI 1.01-2.02, P = .042), with no significant impact on OS (HR 0.86, 95% CI 0.67-1.12, P = .274). However, in subset analysis comparing the impact of splenectomy vs specific spleen sizes, for patients with progressive disease, an improved survival was seen in splenectomised subjects compared to those patients with a palpable spleen length ≥ 15 cm (HR 0.44, 95% CI 0.28-0.69, P < .001), caused by a significant reduction in NRM (HR 0.26, 95% CI 0.14-0.49, P < .001), without significantly increased relapse risk (HR 1.47, 95% CI 0.87-2.49, P = .147). Overall, despite the possible biases typical of retrospective cohorts, this study highlights the potential detrimental effect of massive splenomegaly in transplant outcome and supports the role of splenectomy for myelofibrosis patients with progressive disease and large splenomegaly.

Splenomegaly May Increase the Risk of Rejection in Low-Risk Matched Related Donor Transplant for Thalassemia, This Risk Can Be Partially Overcome by Additional Immunosuppression during Conditioning

Severe thalassemia syndromes (ST) are highly curable by bone marrow transplant (BMT), but rejection may still occur. We retrospectively analyzed our fully matched related donor transplants to establish if isolated splenomegaly is an independent risk factor for rejection and if this risk can be reduced by modifying the conditioning protocol. In this study, we compared rejection rates between patients with and without splenomegaly in 189 consecutive low-risk ST transplants across 2 sequential conditioning regimens: regimen A (August 2013 to December 2016): busulfan (14 mg/kg oral, not adjusted to serum levels), cyclophosphamide (200 mg/kg), and anti-thymocyte globulin (ATG) (Genzyme (Sanofi, Paris, France) 4 mg/kg or Fresenius (Grafalon, Neovii Biotech GmbH, Gräfelfing Germany) 16 mg/kg on days -12 to -10), and regimen B: same backbone as regimen A except fludarabine total dose of 150 mg was added upfront and ATG dose was increased to 7 mg/kg in case of splenomegaly and/or sex-mismatched transplants (January 2017 to September 2018). Compared with regimen A, in regimen B, both overall rejection rates (RRs) (16% versus 6.5%, P = .023) and treatment-related mortality (TRM) (9.9% versus 2.8%, P = .038) improved significantly. By Cox regression analysis, the improvement in RR between the 2 protocols was particularly significant in patients with splenomegaly (RR 54.5% versus 6.5%, P = .00015; TRM 18.2% versus 6.5%, P = .25) (hazard ratio, 4.13; confidence interval, 1.61 to 10.6; P = .003). The increased risk of rejection related to splenomegaly can be overcome by adding fludarabine to the standard ATG-Busulfan- Cyclophosphamide (ATG-Bu-Cy) protocol without significantly increasing transplant-related morbidity and mortality or resorting to splenectomy pre-BMT.

Splenic irradiation before allogeneic stem cell transplantation for myelofibrosis

Splenectomy before allogeneic stem cell transplantation (ASCT) for patients with myelofibrosis (MF) remains a matter of debate, and conflicting results have been reported to date. The procedure seems to fasten post-transplant hematological recovery, but it does not have an impact on survival. The role of pre-transplant splenic irradiation (SI) is much more difficult to evaluate. Forty-four patients (25 males and 19 females) with MF at median age of 49 years at diagnosis (range 14-67) underwent ASCT. The post-transplant outcome was compared between irradiated and non-irradiated patients. Eleven patients received irradiation before transplantation. Median dose of radiation was 1000 cGy (range 600-2400). There was no difference in median time to engraftment between patients with and without previous radiotherapy. Acute and chronic graft versus host disease (GVHD) occurred in 47% and 36% of patients, respectively. There was no difference in GVHD incidence between groups. Eight patients relapsed/progressed in irradiated group versus 17 in non-irradiated (70% vs. 51%; p = 0.3). Transformation to acute myeloid leukemia was observed in 3 patients: 2 in irradiated and 1 in non-irradiated group. In total, 22 patients died with no statistical difference in death rate between irradiated and non-irradiated subjects. The probability of overall survival after transplant for the entire cohort at 2 years was 54% (72% for irradiated and 48% for non-irradiated patients; p = 0.25). Splenic irradiation prior to ASCT for myelofibrosis has not beneficial effect on post-transplant outcome.

Indication and management of allogeneic stem cell transplantation in primary myelofibrosis: a consensus process by an EBMT/ELN international working group

The aim of this work is to produce recommendations on the management of allogeneic stem cell transplantation (allo-SCT) in primary myelofibrosis (PMF). A comprehensive systematic review of articles released from 1999 to 2015 (January) was used as a source of scientific evidence. Recommendations were produced using a Delphi process involving a panel of 23 experts appointed by the European LeukemiaNet and European Blood and Marrow Transplantation Group. Key questions included patient selection, donor selection, pre-transplant management, conditioning regimen, post-transplant management, prevention and management of relapse after transplant. Patients with intermediate-2- or high-risk disease and age <70 years should be considered as candidates for allo-SCT. Patients with intermediate-1-risk disease and age <65 years should be considered as candidates if they present with either refractory, transfusion-dependent anemia, or a percentage of blasts in peripheral blood (PB) >2%, or adverse cytogenetics. Pre-transplant splenectomy should be decided on a case by case basis. Patients with intermediate-2- or high-risk disease lacking an human leukocyte antigen (HLA)-matched sibling or unrelated donor, should be enrolled in a protocol using HLA non-identical donors. PB was considered the most appropriate source of hematopoietic stem cells for HLA-matched sibling and unrelated donor transplants. The optimal intensity of the conditioning regimen still needs to be defined. Strategies such as discontinuation of immune-suppressive drugs, donor lymphocyte infusion or both were deemed appropriate to avoid clinical relapse. In conclusion, we provided consensus-based recommendations aimed to optimize allo-SCT in PMF. Unmet clinical needs were highlighted.

Hematopoietic stem cell transplantation for myelofibrosis: where are we now?

PURPOSE OF REVIEW

A succinct yet comprehensive review of the biology of myeloproliferative neoplasms and therapeutic options with a focus on rational decision making for hematopoietic stem cell transplantation.

RECENT FINDINGS

The introduction of Janus kinase inhibitors for myelofibrosis have ushered in a new era for treatment of constitutional symptoms and splenomegaly in myelofibrosis, but the effect of these agents on the natural history of the disease has yet to be clearly defined. Reduced intensity transplants have emerged as the preferred option with recent evidence suggesting fludarabine and melphalan as the optimal conditioning regimen.

SUMMARY

Myelofibrosis is a rare hematologic malignancy with limited curative therapeutic options. Significant advances in our understanding of disease pathogenesis have led to new targets and new therapeutic options are forthcoming. Hematopoietic stem cell transplantation is at present the only treatment with curative intent; however, the selection of patients who are likely to be best served by this procedure is difficult. As myelofibrosis is an extremely rare disease, randomized clinical trials specifically investigating the role of transplantation in myelofibrosis are unlikely to occur, thus current decision making processes are best guided by retrospective analyses from registry databases and single institution experiences.