Successful engraftment in crossmatch-positive HLA-mismatched peripheral blood stem cell transplantation after depletion of antidonor cytotoxic HLA antibodies with rituximab and donor platelet infusion

Treatment of allosensitized patients receiving allogeneic transplantation

Treatment with PE, rituximab, IVIg, and donor buffy coat is effective in promoting engraftment in patients with DSA <20 000 MFI.

Patients with persistent positive C1q at transplant have a higher risk of engraftment failure and poor survival.

Donor-specific anti-HLA antibodies (DSAs) are a major cause of engraftment failure in patients receiving haploidentical stem cell transplantation (HaploSCT). Effective treatments are needed for these patients, who often have no other donor options and/or are in need to proceed urgently to transplantation. We studied a multimodality treatment with alternate-day plasma exchange (PE), rituximab, intravenous γ globulin (IVIg) and an irradiated donor buffy coat for patients with DSAs at 2 institutions. Thirty-seven patients with a median age of 51 years were treated with this desensitization protocol. Treatment outcomes were compared with a control group of HaploSCT patients without DSAs (n = 345). The majority of patients in the DSA group were female (83.8% vs 37.1% in controls, P < .001) and received stem cells from a child as the donor (67.6% vs 44.1%, P = .002). Mean DSA level before and after desensitization was 10 198 and 5937 mean fluorescence intensity (MFI), respectively, with mean differences of 4030 MFI. Fourteen of 30 tested patients (46.7%) had C1q positivity, while 8 of 29 tested patients (27.6%) remained positive after desensitization. In multivariable analysis, patients with initial DSA > 20 000 MFI and persistent positive C1q after desensitization had a significantly lower engraftment rate, which resulted in significantly higher non-relapse mortality and worse overall survival (OS) than controls, whereas graft outcome and survival of patients with initial DSA < 20 000 MFI and those with negative C1q after treatment were comparable with controls. In conclusion, treatment with PE, rituximab, IVIg, and donor buffy coat is effective in promoting engraftment in patients with DSAs ≤20 000 MFI.

Combination treatment of rituximab and donor platelets infusion to reduce donor-specific anti-HLA antibodies for stem cells engraftment in haploidentical transplantation

BACKGROUND

Donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) in recipients is a risk factor for donor stem cell graft failure in haploidentical hematopoietic stem cell transplantation (haplo-HSCT), and the treatment to reduce the levels of DSAs is not unanimous. This study was to analysis the role of DSAs for stem cell engraftment and to discuss the effective treatment to reduce DSAs in haplo-HSCT.

METHODS

We retrospectively evaluated the levels of DSAs and the effect of the combination treatment of rituximab and donor platelets (PLTs) for donor stem cell engraftment in haplo-HSCT patients from June 2016 to March 2018 at our center.

RESULTS

Nine patients (11.5%) out of the total 78 patients were DSAs-positive and multivariate analysis revealed DSAs was the only factor that affected engraftment. Seven out of the 9 DSAs (+) patients received therapy: Four had antibodies against donor HLA class I (HLA-I) antigens and were administered two therapeutic amounts of donor apheresis platelets (platelet count approximately 3-5 × 10¹¹ ) before donor stem cell infusion and the other three patients received a combination therapy of donor apheresis platelets and rituximab due to the antibodies against both donor HLA-I antigens and HLA class II (HLA-II) antigens. All the seven patients achieved donor stem cell engraftment successfully, and the DSAs levels decreased rapidly after transplantation.

CONCLUSIONS

DSAs is an important factor affecting engraftment in haplo-HSCT. Donor platelet transfusion is one simple and effective treatment for HLA-I DSAs, and a combination therapy should be administered if patients have both HLA-I and HLA-II antibodies.

[Effects of preexisting donor-specific HLA antibodies for graft failure in un-manipulated haploidentical hematopoietic stem cell transplantation]

目的

探讨单倍体相合造血干细胞移植中HLA供者特异性抗体（DSA）对干细胞植入的影响以及处理方法。

方法

采用免疫磁珠液相芯片技术，对2016年6月至2017年5月拟行单倍体相合造血干细胞移植患者进行HLA抗体及DSA的检测，对已完成移植患者进行DSA与植入失败相关性分析，检测移植前后DSA水平，探索针对DSA的处理方法。

结果

共检测了92例拟行单倍体相合造血干细胞移植患者的HLA抗体，其中16例（17.4%）存在HLA抗体，6例（6.5%）DSA阳性。在常规清髓性预处理单倍体相合移植中，26例DSA阴性患者中有24例成功植入，仅有2例发生植入失败，而采用常规预处理的4例DSA阳性患者中仅有1例成功植入，其余3例发生植入失败，二组患者植入率差异有统计学意义[92.3%（24/26）对25.0%（1/4），χ²=8.433，P=0.004]。多因素分析显示，DSA是影响供者干细胞植入的唯一因素[OR=12.0（95% CI 1.39~103.5），P=0.024]。6例DSA阳性的患者中，4例次在移植时采取了针对DSA的措施，均获得供者干细胞顺利植入，其中3例HLA-Ⅰ类DSA阳性患者（首次移植2例、二次移植1例）在输入供者干细胞之前输入供者血小板，另1例HLA-Ⅰ、HLA-Ⅱ类DSA并存患者在二次移植时更换供者并给予全身放疗、利妥昔单抗及供者血小板输注。

结论

DSA是导致单倍体相合造血干细胞植入失败的关键因素，移植前应进行常规检查，DSA阳性患者应选用DSA阴性供者；无合适供者时，应采取适当措施降低DSA水平以促进干细胞植入。

The European Society for Blood and Marrow Transplantation (EBMT) Consensus Guidelines for the Detection and Treatment of Donor-specific Anti-HLA Antibodies (DSA) in Haploidentical Hematopoietic Cell Transplantation

Haploidentical donors are now increasingly considered for transplantation in the absence of HLA-matched donors or when an urgent transplant is needed. Donor-specific anti-HLA antibodies (DSA) have been recently recognized as an important barrier against successful engraftment of donor cells, which can affect transplant survival. DSA appear more prevalent in this type of transplant due to higher likelihood of alloimmunization of multiparous females against offspring's HLA antigens, and the degree of mismatch. Here we summarize the evidence for the role of DSA in the development of primary graft failure in haploidentical transplantation and provide consensus recommendations from the European Society for Blood and Marrow Transplant Group on testing, monitoring, and treatment of patients with DSA receiving haploidentical hematopoietic progenitor cell transplantation.

Donor-Specific Anti-HLA Antibodies in Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (AHSCT) is a curative treatment for a wide variety of hematological diseases. In 30% of the cases, a geno-identical donor is available. Any other situation displays some level of human leukocyte antigen (HLA) incompatibility between donor and recipient. Deleterious effects of anti-HLA immunization have long been recognized in solid organ transplant recipients. More recently, anti-HLA immunization was shown to increase the risk of primary graft failure (PGF), a severe complication of AHSCT that occurs in 3-4% of matched unrelated donor transplantation and up to 15% in cord blood transplantation and T-cell depleted haplo-identical stem cell transplantation. Rates of PGF in patients with DSA were reported to be between 24 and 83% with the highest rates in haplo-identical and cord blood transplantation recipients. This led to the recommendation of anti-HLA antibody screening to detect donor-specific antibodies (DSA) in recipients prior to AHSCT. In this review, we highlight the role of anti-HLA antibodies in AHSCT and the mechanisms that may lead to PGF in patients with DSA, and discuss current issues in the field.

Desensitization with plasma exchange in a patient with human leukocyte antigen donor-specific antibodies before T-cell-replete haploidentical transplantation

BACKGROUND

The presence of human leukocyte antigen donor-specific antibodies (DSAs) increases the risk of graft failure in T-cell-replete haploidentical hematopoietic stem cell transplantation (haplo-HSCT) CASE REPORT: A 49-year-old female with high-risk acute myeloid leukemia in first complete remission received a haplo-HSCT from her daughter. Pretransplant recipient screening examination showed high DSAs levels against unshared class I leukocyte antigens.

RESULTS

The patient underwent a desensitization program consisting of plasma exchange (PEX), polyvalent intravenous (IV) immunoglobulins, and IV tacrolimus and mycophenolate mofetil (MMF). This protocol resulted in the disappearance of the DSA anti HLA B41. Engraftment was prompt with stable full donor chimerism.

CONCLUSIONS

This case report suggests that the adopted scheme is safe for reducing DSA levels and facilitating donor engraftment in patients scheduled for haplo-HSCT.

Donor Specific Anti-HLA Antibody and Risk of Graft Failure in Haploidentical Stem Cell Transplantation

Outcomes of allogeneic hematopoietic stem cell transplantation (AHSCT) using HLA-half matched related donors (haploidentical) have recently improved due to better control of alloreactive reactions in both graft-versus-host and host-versus-graft directions. The recognition of the role of humoral rejection in the development of primary graft failure in this setting has broadened our understanding about causes of engraftment failure in these patients, helped us better select donors for patients in need of AHSCT, and developed rational therapeutic measures for HLA sensitized patients to prevent this unfortunate event, which is usually associated with a very high mortality rate. With these recent advances the rate of graft failure in haploidentical transplantation has decreased to less than 5%.

Desensitization for solid organ and hematopoietic stem cell transplantation

Desensitization protocols are being used worldwide to enable kidney transplantation across immunologic barriers, i.e. antibody to donor HLA or ABO antigens, which were once thought to be absolute contraindications to transplantation. Desensitization protocols are also being applied to permit transplantation of HLA mismatched hematopoietic stem cells to patients with antibody to donor HLA, to enhance the opportunity for transplantation of non-renal organs, and to treat antibody-mediated rejection. Although desensitization for organ transplantation carries an increased risk of antibody-mediated rejection, ultimately these transplants extend and enhance the quality of life for solid organ recipients, and desensitization that permits transplantation of hematopoietic stem cells is life saving for patients with limited donor options. Complex patient factors and variability in treatment protocols have made it difficult to identify, precisely, the mechanisms underlying the downregulation of donor-specific antibodies. The mechanisms underlying desensitization may differ among the various protocols in use, although there are likely to be some common features. However, it is likely that desensitization achieves a sort of immune detente by first reducing the immunologic barrier and then by creating an environment in which an autoregulatory process restricts the immune response to the allograft.

The role of HLA antibodies in allogeneic SCT: is the 'type-and-screen' strategy necessary not only for blood type but also for HLA?

The role of HLA antibodies in SCT has drawn increasing attention because of the significantly increased number of patients who receive HLA-mismatched SCT, including cord blood transplantation, haploidentical SCT and unrelated SCT. Technical advancements in the methods of HLA Ab testing have realized rapid, accurate and objective identification, as well as quantification of specific HLA antibodies. Recent clinical studies have suggested that the presence of donor-specific HLA antibodies (DSA) in patients is associated with graft failure in HLA-mismatched SCT when the above-listed stem cell sources are used and results in different impacts. Of note, most of the 'HLA-matched' unrelated SCT actually involve HLA mismatches in HLA-DP and the presence of antibodies against this locus has been reported to be associated with graft failure. Thus, HLA Ab should be examined as a work-up for all patients who undergo SCT from 'alternative donors.' The simplest route for preventing HLA Ab-mediated graft failure in Ab-positive patients is to avoid donors who possess the target Ag of HLA antibodies. If SCT from such donors must be performed, treatment for DSA before SCT may improve the chances of successful donor engraftment.

Incidence of humoral sensitization in HLA partially mismatched hematopoietic stem cell transplantation

As part of the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), seven centers participated in a collaborative project to determine whether any significant humoral sensitization occurred post-transplant among recipients of HLA partially mismatched hematopoietic cell transplants (HCTs). A total of 140 donor/recipient pairs were enrolled with a total of 367 pre-and post-transplant sera analyzed. The majority of the samples (69.1%) were obtained within 30-90 days post-HCT. HLA-specific antibodies were defined using single antigen bead assays on a Luminex platform with a positive cutoff value of 1000 normalized median fluorescence intensity (MFI). There was an overall incidence of post-HCT sensitization toward donor HLA mismatches of 5.7%; however, all cases were among recipients of one HLA haplotype-mismatched grafts under nonmyeloablative, pre-transplant conditioning. Among the one haplotype-mismatched recipients, 15.7% (8/51) developed donor HLA-specific antibodies and 29.4% also had antibodies directed toward third party HLA antigens. Among the donor-specific antibodies, 9.8% were directed toward HLA class I antigens; 7.8% were against class II antigens; and 2.0% had both class I and II specificity. The relative strength of post-transplant antibodies was low with no significant difference in the mean maximum MFI values between third party and donor-specific antibodies. Because only a small number (10.2%) of the post-transplant samples were obtained 180 days or more post-HCT, longer term study is needed to evaluate any clinical relevance of these low-to-moderate levels of donor-specific antibody in one haplotype-mismatched recipients, as well as to determine whether any other antibodies occur at later times.