Subsequent malignancies after allogeneic hematopoietic stem cell transplantation

Molecular disparity of HLA-DPB1 is associated with the development of subsequent solid cancer after allogeneic hematopoietic stem cell transplantation

BACKGROUND

An increased incidence of subsequent solid cancers (SSCs) has been reported in long-term survivors of allogeneic hematopoietic stem cell transplantation (allo-HSCT), and SSC is associated with inferior mortality and morbidity. Previous studies showed that the incidence of SSC is significantly higher in those who underwent allo-HSCT from HLA-mismatched donors, suggesting that persistent alloimmunity may predispose patients to SSCs. It was recently reported that, in a cohort of patients who received allo-HSCT from an unrelated donor matched at HLA-A, -B, -C, -DRB1/3/4/5, and -DQB1 loci, HLA-DPB1 alloimmunity determined by high mismatched eplets (MEs) and Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) score (PS), was associated with relapse protection and increased risk of acute graft-versus-host disease (GVHD).

METHODS

In the present study, the impact of HLA-DPB1 alloimmunity assessed by molecular mismatch algorithms on the development of SSCs in a cohort of 1514 patients who underwent allo-HSCT for hematologic malignancies was further investigated. ME load at the HLA-DPB1 locus was measured using the HLAMatchmaker module incorporated in HLA Fusion software, and the PS for mismatched HLA-DPB1 was calculated using the HSCT module from the PIRCHE online matching service.

RESULTS

In multivariable analysis after adjusting for baseline risk factors, higher ME, PS-I, and PS-II in the GVH direction, but not in the HVG direction, were associated with an increased risk of SSCs (ME: subdistribution hazard ratio [SHR] 1.58, p = .01; PS-I: SHR 1.59, p = .009; PS-II: SHR 1.71, p = .003). In contrast, nonpermissive HLA-DPB1 mismatches defined by the conventional T-cell epitope algorithm were not predictive of the risk of SSCs. Moreover, posttransplant cyclophosphamide-based GVHD prophylaxis was associated with a reduced risk of subsequent solid cancer (SHR 0.34, p = .021).

CONCLUSIONS

These results indicate for the first time that increased GVH alloreactivity could contribute to the development of SSCs in allo-HSCT survivors.

Incidence of subsequent malignancies after total body irradiation-based allogeneic HSCT in children with ALL - long-term follow-up from the prospective ALL-SCT 2003 trial

Total body irradiation (TBI)-based conditioning is associated with superior leukemia-free survival in children with ALL undergoing HSCT. However, the risk for subsequent malignant neoplasms (SMN) remains a significant concern. We analyzed 705 pediatric patients enrolled in the prospective ALL-SCT-BFM-2003 trial and its subsequent registry. Patients >2 years received conditioning with TBI 12 Gy/etoposide (n = 558) and children ≤2 years of age or with contraindications for TBI received busulfan/cyclophosphamide/etoposide (n = 110). The 5- and 10-year cumulative incidence of SMN was 0.02 ± 0.01 and 0.13 ± 0.03, respectively. In total, 39 SMN (34 solid tumors, 5 MDS/AML) were diagnosed in 33 patients at a median of 5.8 years (1.7-13.4), exclusively in the TBI group. Of 33 affected patients, 21 (64%) are alive at a median follow-up of 5.1 years (0-9.9) after diagnosis of their first SMN. In univariate analysis, neither age at HSCT, donor type, acute GVHD, chronic GVHD, nor CMV constituted a significant risk factor for SMN. The only significant risk factor was TBI versus non-TBI based conditioning. This analysis confirms and quantifies the increased risk of SMN in children with ALL after conditioning with TBI. Future strategies to avoid TBI will need careful tailoring within prospective, controlled studies to prevent unfavorable outcomes.

Modifying the tumour microenvironment and reverting tumour cells: New strategies for treating malignant tumours

The tumour microenvironment (TME) plays a pivotal role in tumour fate determination. The TME acts together with the genetic material of tumour cells to determine their initiation, metastasis and drug resistance. Stromal cells in the TME promote the growth and metastasis of tumour cells by secreting soluble molecules or exosomes. The abnormal microenvironment reduces immune surveillance and tumour killing. The TME causes low anti‐tumour drug penetration and reactivity and high drug resistance. Tumour angiogenesis and microenvironmental hypoxia limit the drug concentration within the TME and enhance the stemness of tumour cells. Therefore, modifying the TME to effectively attack tumour cells could represent a comprehensive and effective anti‐tumour strategy. Normal cells, such as stem cells and immune cells, can penetrate and disrupt the abnormal TME. Reconstruction of the TME with healthy cells is an exciting new direction for tumour treatment. We will elaborate on the mechanism of the TME to support tumours and the current cell therapies for targeting tumours and the TME—such as immune cell therapies, haematopoietic stem cell (HSC) transplantation therapies, mesenchymal stem cell (MSC) transfer and embryonic stem cell‐based microenvironment therapies—to provide novel ideas for producing breakthroughs in tumour therapy strategies.

Chronic myeloid leukemia following liver transplantation: A case report

Long-term utilization of immunosuppression in organ transplant recipients leads to decreased immune-mediated tumor surveillance and increased risk of developing malignant tumors. However, chronic myeloid leukemia (CML) following living donor liver transplantation (LDLT) is rarely reported. The current case report presents a 42-year-old male patient who developed CML 14 months following LDLT. The patient achieved complete hematologic remission and early molecular response at 3 months imatinib treatment and major molecular response at 12 months imatinib treatment. The pathogenesis, risk factors, treatment and prognosis for CML following liver transplantation are unclear. Therefore, further analysis through accumulation of cases will be of great importance to prevent and treat this rare complication following liver transplantation.