High incidence of graft failure in unrelated cord blood transplantation using a reduced-intensity preparative regimen consisting of fludarabine and melphalan

Development of an umbilical cord blood transplantation-specific nonrelapse mortality risk assessment score

ABSTRACT

Higher rate of nonrelapse mortality (NRM) remains yet to be resolved in umbilical cord blood transplantation (UCBT). Considering that UCBT has some unique features compared with allogeneic hematopoietic cell transplantation from other graft sources, a UCBT-specific NRM risk assessment system is required. Thus, in this study, we sought to develop a UCBT-specific NRM Risk Assessment (CoBRA) score. Using a nationwide registry database, we retrospectively analyzed 4437 recipients who had received their first single-unit UCBT. Using the backward elimination method, we constructed the CoBRA score in a training cohort (n = 2687), which consisted of recipients age ≥55 years (score 2), hematopoietic cell transplantation-specific comorbidity index ≥3 (score 2), male recipient, graft-versus-host disease prophylaxis other than tacrolimus in combination with methotrexate, performance status (PS) 2 to 4, HLA allele mismatch ≥ 2, refined Disease Risk Index high risk, myeloablative conditioning, and CD34+ cell doses < 0.82 × 105/kg (score 1 in each). The recipients were categorized into 3 groups: low (0-4 points), intermediate (5-7 points), and high (8-11 points) groups according to the CoBRA score. In the validation cohort (n = 1750), the cumulative incidence of NRM at 2 years was 14.9%, 25.5%, and 47.1% (P < .001), and 2-year overall survival (OS) was 74.2%, 52.7%, and 26.3% (P < .001) in the low, intermediate, and high groups, respectively. In summary, the CoBRA score could predict the NRM risk as well as OS after UCBT. Further external validation will be needed to confirm the significance of the CoBRA score.

Improved survival after single-unit cord blood transplantation using fludarabine and melphalan-based reduced-intensity conditioning for malignant lymphoma: impact of melphalan dose and graft-versus-host disease prophylaxis with mycophenolate mofetil

We evaluated 413 adult patients with lymphoma who underwent unrelated cord blood transplantation (UCBT) with fludarabine and melphalan (FM)-based reduced-intensity conditioning between 2002 and 2017 to investigate longitudinal changes in outcomes and the optimal melphalan dose and graft-versus-host disease (GVHD) prophylaxis regimen. Outcomes were compared between FM80/100 (melphalan dose: 80 or 100 mg/m²) and FM140 (melphalan dose: 140 mg/m²), as well as between calcineurin inhibitor (CNI) plus methotrexate (MTX), CNI plus mycophenolate mofetil (MMF), and CNI alone. The 3-year overall survival (OS) and non-relapse mortality (NRM) rates improved over time (OS: 27% in 2000s vs. 42% in 2010s, p < 0.001; NRM: 43% in 2000s vs. 26% in 2010s, p < 0.001). Multivariable analysis showed that in the 2000s, melphalan dose and GVHD prophylaxis regimen did not affect any outcomes. In the 2010s, FM80/100 (vs. FM140) related to better OS (hazard ratio [HR] 0.62, p = 0.01) and NRM (HR 0.52, p = 0.016). MTX + CNI and CNI alone (vs. CNI + MMF) related to worse OS (CNI + MTX, HR 2.01, p < 0.001; CNI alone, HR 2.65, p < 0.001) and relapse/progression (CNI + MTX, HR 2.40, p < 0.001; CNI alone, HR 2.13, p = 0.023). In recent years, the use of FM80/100 and CNI + MMF significantly reduced the risk of NRM and relapse/progression, respectively, and resulted in better OS after UCBT for lymphoma.

Better outcomes of modified myeloablative conditioning without antithymocyte globulin versus myeloablative conditioning in cord blood transplantation for hematological malignancies: A retrospective (development) and a prospective (validation) study

Cord blood transplantation (CBT) is an effective option for treating hematological malignancies, but graft failure (GF) remains the primary cause of therapy failure. Thus, based on myeloablative conditioning (MAC) of busulfan with cyclophosphamide (Bu/Cy) or total body irradiation with Cy (TBI/Cy), fludarabine (Flu) was added to Bu/Cy and cytarabine (CA) to TBI/Cy for a modified myeloablative conditioning (MMAC). To compare the prognosis of MMAC with MAC, we conducted a retrospective study including 58 patients who underwent CBT with MAC or MMAC from 2000 to 2011. Neutrophil and platelet engraftment rate, overall survival (OS) and disease free survival (DFS) were significantly higher in the MMAC group (adjusted hazard ratio [HR], 2.58, 2.43, 0.36 and 0.37; p < 0.01, p = 0.01, p = 0.02 and p = 0.02, separately). Nonrelapse mortality (NRM) was comparable (p = 0.183). To validate the outcomes noted in the MMAC group, we conducted a prospective single‐arm clinical trial including 188 patients who underwent CBT with MMAC from 2011 to 2015. Engraftment rate, survival and NRM of the MMAC group in the prospective trail (MMAC‐P) were similar to the MMAC group in the retrospective study (MMAC‐R). This study is the first to demonstrate the superiority of MMAC to MAC in CBT for hematological malignancies.

What's new?

Cord blood transplants can help patients with blood cancer, but too often, the transplant fails due to immune rejection or other problems. Typically, patients receive myeloablative conditioning (MAC) prior to CBT, but more intense regimen might improve transplant success. Here, the authors compared the success of modified myeloablative conditioning (MMAC) with conventional MAC by looking at 58 patients over an 11‐year period. They then followed up with a four‐year prospective study, including 188 patients who received cord blood transplant with MMAC. The modified conditioning regimen boosted graft success and improved survival of patients with hematological cancers.

Phase II study of intrabone single unit cord blood transplantation for hematological malignancies

The outcomes of cord blood transplantation with non‐irradiated reduced‐intensity conditioning for hematological malignancies need to be improved because of graft failure and delayed engraftment. Intrabone infusion of cord blood cells has the potential to resolve the problems. In this phase II study, 21 adult patients with hematological malignancy received intrabone transplantation of serological HLA‐A, B, and DR ≥4/6 matched single cord blood with a median number of cryopreserved total nucleated cells of 2.7 × 10⁷/kg (range, 2.0–4.9 × 10⁷/kg) following non‐irradiated fludarabine‐based reduced‐intensity conditioning. Short‐term methotrexate and tacrolimus were given as graft‐versus‐host disease prophylaxis, and granulocyte colony‐stimulating factor was given after transplantation. No severe adverse events related to intrabone injection were observed. The cumulative incidences of neutrophils ≥0.5 × 10⁹/L, reticulocytes ≥1%, and platelets ≥20 × 10⁹/L recoveries were 76.2%, 71.4%, and 76.2%, respectively, with median time to recoveries of 17, 28, and 32 days after transplantation, respectively. The probability of survival with neutrophil engraftment on day 60 was 71.4%, and overall survival at 1 year after transplantation was 52.4%. The incidences of grade II–IV and III–IV acute graft‐versus‐host disease were 44% and 19%, respectively, with no cases of chronic graft‐versus‐host disease. The present study showed the safety of direct intrabone infusion of cord blood. Further analysis is required to confirm the efficacy of intrabone single cord blood transplantation with non‐irradiated reduced‐intensity conditioning for adult patients with hematological malignancy. This study was registered with UMIN‐CTR, number 000000865.

Alemtuzumab, Fludarabine, Low-Dose TBI, and Double Umbilical Cord Transplant for Primary Graft Failure in a Patient with Recurrent HLH

Graft failure occurs at relatively low frequency, but commonly in hemophagocytic lymphohistiocytosis (HLH), especially with umbilical cord blood transplant (UCBT). No standard approaches to management of graft failure exist. We present a challenging case of relapsed HLH following first UCBT with primary graft failure following second UCBT. We report a novel reduced intensity conditioning regimen of alemtuzumab, 4 Gy total body irradiation and fludarabine for salvage of primary graft failure followed by double UCBT. The reported patient successfully engrafted with 100% donor chimerism following salvage UCBT with no occurrence of acute or chronic graft-versus-host disease.

A novel reduced-intensity umbilical cord blood transplantation using a recombinant G-CSF combined with high-dose Ara-C for active myeloid malignancies

Non-remitting patients with hematologic myeloid malignancies have poor prognosis. To overcome this problem, we investigated the use of reduced-intensity preconditioning umbilical cord blood transplantation (RICBT) combined with recombinant G-CSF (rG-CSF) with high-dose Ara-C, fludarabine, melphalan, and 4 Gy of TBI in a phase I/II study in patients with non-remitting myeloid hematologic malignancies. Thirteen patients were enrolled, including 12 with non-remitting AML and one patient with blastic crisis CML (CML-BC). The patients' median age was 45 years, with a median comorbidity index of 4. All patients received 4/6 serological HLA-antigen matched unrelated umbilical cord blood. All patients were engrafted within 30 days after RICBT (median, 20 days; range, 14-29) and achieved complete remission without prior hematopoiesis. Common grade III non-hematologic toxicities included eight cases of transient mucositis (62%) and six cases of febrile neutropenia (46%). Transplant-related mortality was 7.7%. The 1-year overall survival was 28.6% in cases without post-RICBT treatment and 83.3% in cases with post-RICBT treatment. These data suggest that in active AML and CML-BC, the combination of rG-CSF with high-dose Ara-C and fludarabine/melphalan/4 Gy TBI with a reduced-intensity preconditioning regimen is well tolerated, secures engraftment and has significant anti-leukemia activity. In addition, performing post-RICBT treatment may provide high-quality long-term survival and remission.

Double umbilical cord blood transplantation in patients with hematologic malignancies using a reduced-intensity preparative regimen without antithymocyte globulin

Reduced-intensity conditioning (RIC) regimens in cord blood transplant (CBT) are increasingly utilized for older patients and those with comorbidities. However, the optimal conditioning regimen has not yet been established and remains a significant challenge of this therapeutic approach. Antithymocyte globulin (ATG) has been incorporated into conditioning regimens in order to decrease the risk of graft failure; however, use of ATG is often associated with infusion reactions and risk of post-transplant complications. We report the results of a non-ATG-containing RIC regimen, where patients received 2 Gy TBI unless they were considered to be at higher risk of graft failure, in which case they received 3 Gy of TBI. Thirty patients underwent CBT using this protocol for high-risk hematological malignancies. There was only one case of secondary and no cases of primary graft failure. At 1 year, estimates of non-relapse mortality, OS and PFS were 29%, 53% and 45%, respectively. The cumulative incidences of grade III-IV acute and chronic GVHD were 14% and 18%, respectively. In summary, the results of this study demonstrate that this non-ATG-containing conditioning regimen provides a low incidence of graft failure without increasing regimen-related toxicity.

Fludarabine, melphalan, thiotepa and anti-thymocyte globulin conditioning for unrelated cord blood transplant

Unrelated cord blood transplant (CBT) is an alternative treatment option for patients who lack a matched donor. However, the optimal type and intensity of the preparative regimen remains unclear. We evaluated the toxicity and outcomes of a conditioning regimen consisting of melphalan 140 mg/m(2) (day - 8), thiotepa 10 mg/kg (day - 7), fludarabine 160 mg/m(2) over 4 days (days - 6 to - 3) and rabbit antithymocyte globulin (ATG) 1.25 mg/kg (day - 4) and 1.75 mg/kg (day - 3) (FMT). Forty-seven patients with advanced hematologic malignancies with a median age of 23 years (30 adults and 17 children) were treated. Sixty percent of patients were in remission at transplant. Ninety-one percent of the patients engrafted neutrophils after a median of 22 days, and all but one of the patients achieving donor engraftment had hematopoietic recovery with 100% cord blood-derived cells. Grade 3 gastrointestinal toxicity was the major non-hematopoietic toxicity, occurring in 32% of patients. Cumulative incidence of day-100 grade II-IV acute graft-versus-host disease (aGVHD) and chronic graft-versus-host disease (cGVHD) was 53% and 34%, respectively, and non-relapse mortality at day 100 and 2 years was 11% and 40%. Two-year disease-free and overall survival rates were 31% and 44%, respectively. These results suggest that FMT is a feasible conditioning regimen for patients undergoing CBT.

Prospective study of one- vs two-unit umbilical cord blood transplantation following reduced intensity conditioning in adults with hematological malignancies

As the threshold nucleated cell dose for one-unit umbilical cord blood (UCB) in adults has not to date been firmly established, we prospectively compared one- vs two-unit UCB transplantation after reduced intensity conditioning (RIC) in adult patients with hematological malignancies. Study design specified one-UCB unit if the cryopreserved total nucleated cell (TNC) dose was 2.5 × 10(7)/kg recipient weight, otherwise two units matched at minima of 4/6 HLA loci to the patient and 3/6 to each other were infused. A total of 27 patients received one unit; 23 patients received two units. Median time to ANC >500/μL was 24 days (95% confidence interval 22-28 days), 25 days for one unit and 23 days for two units (P=0.99). At day 100, ANC >500/μL was 88.4 and 91.3% in the one- and two-unit groups (P=0.99), respectively. Three-year EFS was 28.6% and 39.1% in the one- and two-unit groups (P=0.71), respectively. Infusion of two units was associated with a significantly lower relapse risk, 30.4% vs 59.3% (P=0.045). Infused cell doses (TNC, CD3(+), CD34(+) and CD56(+)CD3(neg)) did not impact on engraftment, OS or EFS. Taken together, one-unit UCB transplantation with a threshold cell dose 2.5 × 10(7)/kg recipient weight after RIC is a viable option for adults, although infusion of two units confers a lower relapse incidence.

Immune Reactions following Cord Blood Transplantations in Adults

Cord blood transplantation (CBT) is an attractive alternative therapy in adult patients with advanced hematological malignancies in whom matched donors are unavailable. However, the risk of complications, especially infections, post-CBT increases the mortality rates in these patients. Although the incidence of acute and chronic graft versus host disease (GVHD) post-CBT is lower than that following bone marrow transplantation and peripheral blood stem cell transplantation (SCT), the additional immunosuppressive therapy required to treat it could increase the mortality in these patients. Further, chronic GVHD following CBT is milder and responds better to treatment than that occurring after bone marrow transplants. Unlike bone marrow transplantation, the onset of GVHD is a positive prognostic indicator of overall survival in patients receiving CBT, due to the graft versus malignancy (GVM) effect. This paper focuses on the immune reactions following CBT and aims to elucidate a management strategy for acute and chronic GVHD.

Umbilical cord blood: current status and future directions

Once considered biological waste, umbilical cord blood (UCB) has become an accepted source of haematopoietic stem cells (HSCs). With initial success in the pediatric setting, UCB transplantation continues to gain favor in the adult patient population. Novel approaches to UCB transplantation include use of two units and a variety of graft manipulations. Additional uses for UCB are currently being explored and include applications in regenerative medicine and immunotherapy.

Cord blood transplants: one, two or more units?

PURPOSE OF REVIEW

This review summarizes the current status of double-unit cord blood transplantation (CBT) to improve engraftment, reduce transplant-related mortality, and improve disease-free survival.

RECENT FINDINGS

Transplantation of cord blood provides a potentially curative therapy for many patients without a suitably human leukocyte antigen-matched related or unrelated donor. Single-unit CBT outcomes have been compromised, however, in adults and larger children by limited cell dose. The introduction of double-unit CBT has improved engraftment and transplant-related mortality in adult patients transplanted for hematologic malignancies, with recent data also suggesting a protection against relapse. These improved outcomes are seen despite only a single unit being responsible for sustained donor hematopoiesis in nearly all patients. The study of double-unit CBT provides unique insights into transplant biology, with emerging data suggesting unit dominance is related to unit viability and unit-versus-unit immune interactions. Multiple unit CBT further serves as a platform to test novel graft manipulations.

SUMMARY

The development of double-unit CBT now allows the majority of patients, regardless of size or racial/ethnic background, access to transplant therapy. Ongoing investigation will serve to further improve outcomes and expand the role of CBT in the future.

Alternative donors hematopoietic stem cells transplantation for adults with acute myeloid leukemia: Umbilical cord blood or haploidentical donors?

Use of allogeneic transplantation for patients with acute myeloid leukemia (AML) depends mainly on the risk of the disease, and HLA matched donor availability. In patients with high-risk leukemia, in the absence of a HLA (human leukocyte antigen) matched donor, alternative donors such as unrelated umbilical cord blood (UCB) or haploidentical donor (haplo) have been currently used. Both strategies have important advantages such as shorter time to transplant, which is particularly relevant to patients requiring urgent transplantation, and tolerance of HLA mismatched graft that make possible that a donor can be found for virtually all patients. However, in spite of higher incidence of graft failure in UCB transplatation recipients and higher relapse incidence after haplo transplants, final outcomes seem to be comparable with HLA matched unrelated hematopoietic stem cell transplantation (bone marrow or peripheral blood). Therefore, the complexity of choosing the best alternative donor will depend on urgency of the transplantation, status and risk of the disease, donor criteria and center experience. Here we review the current status of UCBT and haplo transplants to treat adults with high-risk acute myeloid leukemia and we discuss the main issues associated with the use of both hematopoietic stem cell transplant approaches.

Extending cord blood transplant to adults: dealing with problems and results overall

The development of newer strategies to overcome, in particular, the cell dose limitation, has increased the availability of umbilical cord blood (UCB) as a source of hematopoietic stem cells (HSC) for transplantation of adults. Among these strategies is the development of the double UCB, ex vivo, and reduced-intensity transplantation platforms. Several ongoing registry-based and single-institution and multicenter clinical trials are investigating ways to make UCB transplantation safer and to improve the outcomes of adults after UCB transplantation. We review the background data and promising newer strategies that will further expand the utilization of UCB for the treatment of adults.

CD34+ cell dose and establishment of full donor chimerism at day +100 are important factors for survival with reduced-intensity conditioning with fludarabine and melphalan before allogeneic hematopoietic SCT for hematologic malignancies

The combination of fludarabine and melphalan as a reduced-intensity conditioning (RIC) regimen extends allogeneic hematopoietic SCT (HSCT) as a therapeutic option for elderly or frail patients with relapsed, refractory or other high-risk hematologic malignancies. Whether any modifiable factors exist that could improve survival before or immediately after HSCT is unknown. We reviewed the medical records of the first 50 patients at our institution to undergo fludarabine/melphalan RIC from September 2000 to September 2007 to determine factors associated with survival. A total of 25 (50%) patients had undergone prior HSCT and as such was a high-risk group of patients. On multivariate analysis, CD34(+) cell dose greater than 5.5 × 10(6) per kg (risk ratio (RR) 0.44, 95% CI 0.19-0.98, P=0.02) and full donor chimerism at day +100 (RR 0.17, 95% CI 0.06-0.64, P=0.002) remained independent prognostic factors. In our series, achievement of full donor chimerism at day +100 was associated with an approximately 70% 2-year survival, a favorable outcome in this high-risk group of patients. Although the infused CD34(+) cell dose is a modifiable variable, whether donor lymphocyte infusions or other immunologic interventions should be performed to promote the establishment of full chimerism early post transplant remains unknown.

Cord blood transplantation for haematological malignancies: conditioning regimens, double cord transplant and infectious complications

Growing evidence supports the efficacy of cord blood transplantation (CBT) to treat patients with haematological malignancies, and the number of CBTs is rapidly increasing. Herein, we review considerations regarding conditioning regimens for CBT, the impact of double unit transplantation on CBT outcomes, and data regarding infectious complications following CBT.

Early central nervous complications after umbilical cord blood transplantation for adults

Early central nervous complications (CNS) are significant after allogeneic stem cell transplantation; however, the clinical characteristics of early CNS complications have not yet been well described. The medical record of 77 patients who underwent cord blood transplantation (CBT) between March 2001 and November 2005, at 8 centers of the Nagoya Blood and Marrow Transplantation Group were retrospectively reviewed. The preparative regimen included myeloablative CBT (n = 31) or reduced-intensity (RI)-CBT (n = 46). Of the 77 patients, 10 (13%) developed early CNS complications. Causes included Cyclosporine encephalopathy (n = 5), tacrolimus encephalopathy (n = 2), thrombocytic microangiopathy (n = 1), and unknown (n = 3). The median time of onset was 19 days (range: 2-58 days). All of the 10 patients developed impaired consciousness. Seizures developed in 6 patients. Early CNS complications spontaneously subsided in 3 patients. Three patients responded to cyclosporine or tacrolimus discontinuation. The remaining 4 patients died within 30 days of developing of early CNS complications. No relationship was detected between the preparative regimen and the onset of early CNS complications, while an HLA disparity showed borderline significance (hazard ratio, 3.24; 95% confidential interval, 0.94-11.20; P = .06). Early CNS complications are a significant problem after CBT, and the clinician has to be aware of the possibility of these complications.