Reduced-intensity conditioning regimens for allogeneic transplantation in children with acute lymphoblastic leukemia

[Efficacy and safety of secondary allogeneic hematopoietic stem cell transplantation in 70 patients with recurrent hematologic malignancies after transplantation]

Objectives: To investigate the role of donor change in the second hematopoietic stem cell transplantation (HSCT2) for hematological relapse of malignant hematology after the first transplantation (HSCT1) . Methods: We retrospectively analyzed patients with relapsed hematological malignancies who received HSCT2 at our single center between Mar 1998 and Dec 2020. A total of 70 patients were enrolled[49 males and 21 females; median age, 31.5 (3-61) yr]. Results: Forty-nine male and 21 female patients were enrolled in the trial. At the time of HSCT2, the median age was 31.5 (3-61) years old. Thirty-one patients were diagnosed with acute myeloid leukemia, 23 patients with ALL, and 16 patients with MDS or other malignant hematology disease. Thirty patients had HSCT2 with donor change, and 40 patients underwent HSCT2 without donor change. The median relapse time after HSCT1 was 245.5 (26-2 905) days. After HSCT2, 70 patients had neutrophil engraftment, and 62 (88.6%) had platelet engraftment. The cumulative incidence of platelet engraftment was (93.1±4.7) % in patients with donor change and (86.0±5.7) % in patients without donor change (P=0.636). The cumulative incidence of CMV infection in patients with and without donor change was (64.0±10.3) % and (37.0±7.8) % (P=0.053), respectively. The cumulative incidence of grade Ⅱ-Ⅳ acute graft versus host disease was (19.4±7.9) % vs (31.3±7.5) %, respectively (P=0.227). The cumulative incidence of TRM 100-day post HSCT2 was (9.2±5.1) % vs (6.7±4.6) % (P=0.648), and the cumulative incidence of chronic graft versus host disease at 1-yr post-HSCT2 was (36.7±11.4) % versus (65.6±9.1) % (P=0.031). With a median follow-up of 767 (271-4 936) days, 38 patients had complete remission (CR), and three patients had persistent disease. The CR rate was 92.7%. The cumulative incidences of overall survival (OS) and disease-free survival (DFS) 2 yr after HSCT2 were 25.8% and 23.7%, respectively. The cumulative incidence of relapse, OS, and DFS was (52.6±11.6) % vs (62.4±11.3) % (P=0.423), (28.3±8.6) % vs (23.8±7.5) % (P=0.643), and (28.3±8.6) % vs (22.3±7.7) % (P=0.787), respectively, in patients with changed donor compared with patients with the original donor. Relapses within 6 months post-HSCT1 and with persistent disease before HSCT2 were risk factors for OS, DFS, and CIR. Disease status before HSCT2 and early relapse (within 6 months post-HSCT1) was an independent risk factor for OS, DFS, and CIR post-HSCT2. Conclusion: Our findings indicate that changing donors did not affect the clinical outcome of HSCT2.

Hematopoietic Cell Transplantation after CD19 Chimeric Antigen Receptor T Cell-Induced Acute Lymphoblastic Lymphoma Remission Confers a Leukemia-Free Survival Advantage

Consolidative hematopoietic cell transplantation (HCT) after CD19 chimeric antigen receptor (CAR) T cell therapy is frequently performed for patients with refractory/ relapsed B cell acute lymphoblastic leukemia (B-ALL). However, there is controversy regarding the role of HCT following remission attainment. We evaluated the effect of consolidative HCT on leukemia-free survival (LFS) in pediatric and young adult subjects following CD19 CAR T cell induced remission. We evaluated the effect of consolidative HCT on LFS in pediatric and young adult subjects treated with a 41BB-CD19 CAR T cell product on a phase 1/2 trial, Pediatric and Young Adult Leukemia Adoptive Therapy (PLAT)-02 (ClinicalTrials.gov identifier NCT02028455), using a time-dependent Cox proportional hazards statistical model. Fifty of 64 subjects enrolled in PLAT-02 phase 1 and early phase 2 were evaluated, excluding 14 subjects who did not achieve remission, relapsed, or died before day 63 post-CAR T cell therapy. An improved LFS (P = .01) was observed in subjects who underwent consolidative HCT after CAR T cell therapy versus watchful waiting. Consolidative HCT improved LFS specifically in subjects who had no prior history of HCT, with a trend toward significance (P = .09). This benefit was not evident when restricted to the cohort of 34 subjects with a history of prior HCT (P = .45). However, for subjects who had CAR T cell functional persistence of 63 days or less, inclusive of those with a history of prior HCT, HCT significantly improved LFS outcomes (P = .01). These data support the use of consolidative HCT following CD19 CAR T cell-induced remission for patients with no prior history of HCT and those with short functional CAR T cell persistence.

Hematopoietic cell transplantation for acute lymphoblastic leukemia: review of current indications and outcomes

The treatment landscape for patients with acute lymphoblastic leukemia (ALL) is changing. Continued investigation into the biology of ALL, and broader use and more precise methods of measuring residual disease allow for improved risk stratification of patients and identification of the subset of patients at greatest risk of disease relapse and who may benefit from hematopoietic cell transplantation (HCT) in first complete remission. Further, recent advances in HCT preparative regimens, donor selection, graft manipulation, and graft-versus-host disease prophylaxis and treatment have resulted in fewer transplant-related morbidities and mortality and better survival outcomes. Finally, the development of effective immunotherapeutic salvage agents, such as the chimeric antigen receptor T-cell therapy, tisagenlecleucel, have significantly changed the treatment landscape of this disease, allowing patients with advanced disease to be considered for HCT with curative intent. In this review, we will provide an update on the indications and outcome of pediatric and adult ALL.

Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide in Children with High-Risk Leukemia Using a Reduced-Intensity Conditioning Regimen and Peripheral Blood as the Stem Cell Source

The use of haploidentical donor hematopoietic stem cell transplantation with post-transplantation cyclophosphamide (Haplo-PTCy) in children is increasing; however, it is still not clear which preparative regimen is best in this setting. We present the long-term results of 42 patients age <18 years with high-risk leukemia who underwent this procedure using a reduced-intensity conditioning regimen (RIC) and peripheral blood as the stem cell source. Twenty-six patients had acute lymphoblastic leukemia, 13 had acute myelogenous leukemia, 2 had juvenile myelomonocytic leukemia, and 1 had blast crisis of chronic myelogenous leukemia. One-third of the patients were in first remission, 50% were in second remission, 14% were in third remission, and 3% had refractory disease. Neutrophil recovery occurred in 100% of the 40 patients alive at day +30, and transplantation-related mortality at 1 year was 14%. The incidence of acute graft-versus-disease (GVHD) grade III-IV was 17%, and the cumulative incidence of moderate to severe chronic GVHD at 1 year was 29%. The median duration of follow-up for surviving patients was 45 months; overall survival and event-free survival at 36 months were 56% and 46%, respectively. Long-term results of this series show that the use of an RIC regimen with peripheral blood stem cells as the cell source, in children with high-risk leukemia who underwent haplo-PTCy has tolerable toxicity, universal engraftment, and good survival rates.

Successful preemptive therapy with single-dose rituximab for Epstein-Barr virus infection to prevent post-transplant lymphoproliferative disease after pediatric hematopoietic stem cell transplantation

BACKGROUND

The efficacy of preemptive treatment containing rituximab to prevent post-transplant lymphoproliferative disease (PTLD) in children has not yet been fully elucidated.

METHODS

We analyzed 19 pediatric patients who developed high Epstein-Barr virus (EBV) DNAemia (EBV viral load of greater than 40 000 copies/mL) after allogeneic hematopoietic stem cell transplantation (HSCT) and were preemptively administered rituximab. Rituximab was intravenously injected at a dose of 375 mg/m² once the EBV viral load was greater than 40 000 copies/mL.

RESULTS

In all 19 patients, EBV DNAemia was eradicated after a median of 9 days (range, 3-20 days), and PTLD did not occur. One patient had transient fever, and four patients did not fully recover B cell counts after transplantation. We suggested that delayed B cell recovery was caused by chronic graft-versus-host disease (GVHD) related drugs, not rituximab administration. And there were no other infection-related side effects.

CONCLUSIONS

In conclusion, preemptive therapy containing rituximab is expected to reduce the incidence of PTLD after HSCT and improve post-transplantation outcomes in children.

Allogeneic stem cell transplantation in the era of novel therapies for acute lymphoblastic leukaemia

Immunotherapy is changing the treatment of acute lymphoblastic leukaemia (ALL) in adults and children. However, regardless of these new therapies, allogeneic hematopoietic cell transplantation (allo-HCT) still play a key role in the treatment of ALL, although it is uncertain how these new therapies will impact on the transplant procedure and indications. This article reviews the indications of allo-HCT for children and adults diagnosed with ALL, the different sources and conditioning regimens for transplantation as well as the role of measurable residual diseases pre- and post-HCT in the era of the new therapies for ALL.

Reduced-Intensity Haploidentical Bone Marrow Transplantation with Post-Transplant Cyclophosphamide for Solid Tumors in Pediatric and Young Adult Patients

High-risk, recurrent, or refractory solid tumors in pediatric, adolescent, and young adult (AYA) patients have an extremely poor prognosis despite current intensive treatment regimens. We piloted an allogeneic bone marrow transplant platform using reduced-intensity conditioning (RIC) and partially HLA-mismatched (haploidentical) related donors for this population of pediatric and AYA solid tumor patients. Sixteen patients received fludarabine, cyclophosphamide, melphalan, and low-dose total body irradiation RIC haploidentical BMT (haploBMT) followed by post-transplantation cyclophosphamide (PTCy), mycophenolate mofetil, and sirolimus. All assessable patients were full donor chimeras on day 30 with a median neutrophil recovery of 19 days and platelet recovery of 21 days. One patient (7%) exhibited secondary graft failure associated with concomitant infection. The median follow-up time was 15 months. Overall survival was 88%, 56%, and 21% at 6, 12, and 24 months, respectively. Median survival from transplant date was 14 months with a median progression-free survival 7 months. We observed limited graft-versus-host disease in 3 patients and nonrelapse mortality in 1 patient. We demonstrated that RIC haploBMT with PTCy is feasible and has acceptable toxicities in patients with incurable pediatric and AYA solid tumors; thus, this approach serves as a platform for post-transplant strategies to prevent relapse and optimize progression-free survival.

The Cost of Hematopoietic Stem-Cell Transplantation in the United States

BACKGROUND

Hematopoietic stem-cell transplantation (HSCT) requires highly specialized, resource-intensive care. Myeloablative conditioning regimens used before HSCT generally require inpatient stays and are more intensive than other preparative regimens, and may therefore be more costly.

OBJECTIVE

To estimate the costs associated with inpatient HSCT according to the type of the conditioning regimen used and other potential contributors to the overall cost of the procedure.

METHOD

We used data from the Truven Health MarketScan insurance claims database to analyze healthcare costs for pediatric (age <18 years) and adult (age ≥18 years) patients who had autologous or allogeneic inpatient HSCT between January 1, 2010, and September 23, 2013. We developed an algorithm to determine whether conditioning regimens were myeloablative or nonmyeloablative/reduced intensity.

RESULTS

We identified a sample of 1562 patients who had inpatient HSCT during the study period for whom the transplant type and the conditioning regimen were determinable: 398 patients had myeloablative allogeneic HSCT; 195 patients had nonmyeloablative/reduced-intensity allogeneic HSCT; and 969 patients had myeloablative autologous HSCT. The median total healthcare cost at 100 days was $289,283 for the myeloablative allogeneic regimen cohort compared with $253,467 for the nonmyeloablative/reduced-intensity allogeneic regimen cohort, and $140,792 for the myeloablative autologous regimen cohort. The mean hospital length of stay for the index (first claim of) HSCT was 35.6 days in the myeloablative allogeneic regimen cohort, 26.6 days in the nonmyeloablative/reduced-intensity allogeneic cohort, and 21.8 days in the myeloablative autologous regimen cohort.

CONCLUSION

Allogeneic HSCT was more expensive than autologous HSCT, regardless of the regimen used. Myeloablative conditioning regimens led to higher overall costs than nonmyeloablative/reduced-intensity regimens in the allogeneic HSCT cohort, indicating a greater cost burden associated with inpatient services for higher-intensity preparative conditioning regimens. Pediatric patients had higher costs than adult patients. Future research should involve validating the algorithm for identifying conditioning regimens using clinical data.

Nonmyeloablative Haploidentical Bone Marrow Transplantation with Post-Transplantation Cyclophosphamide for Pediatric and Young Adult Patients with High-Risk Hematologic Malignancies

Lower-intensity conditioning regimens for haploidentical blood or marrow transplantation (BMT) are safe and efficacious for adult patients with hematologic malignancies. We report data for pediatric/young adult patients with high-risk hematologic malignancies (n = 40) treated with nonmyeloablative haploidentical BMT with post-transplantation cyclophosphamide from 2003 to 2015. Patients received a preparative regimen of fludarabine, cyclophosphamide, and total body irradiation. Post-transplantation immunosuppression consisted of cyclophosphamide, mycophenolate mofetil, and tacrolimus. Donor engraftment occurred in 29 of 32 (91%), with median time to engraftment of neutrophils >500/µL of 16 days (range, 13 to 22) and for platelets >20,000/µL without transfusion of 18 days (range, 12 to 62). Cumulative incidences of acute graft-versus-host disease (GVHD) grades II to IV and grades III and IV at day 100 were 33% and 5%, respectively. The cumulative incidence of chronic GVHD was 23%, with 7% moderate-to-severe chronic GVHD, according to National Institutes of Health consensus criteria. Transplantation-related mortality (TRM) at 1 year was 13%. The cumulative incidence of relapse at 2 years was 52%. With a median follow-up of 20 months (range, 3 to 148), 1-year actuarial overall and event-free survival were 56% and 43%, respectively. Thus, we demonstrate excellent rates of engraftment, GVHD, and TRM in pediatric/young adult patients treated with this regimen. This approach is a widely available, safe, and feasible option for pediatric and young adult patients with high-risk hematologic malignancies, including those with a prior history of myeloablative BMT and/or those with comorbidities or organ dysfunction that preclude eligibility for myeloablative BMT.

Comparison of a fludarabine and melphalan combination-based reduced toxicity conditioning with myeloablative conditioning by radiation and/or busulfan in acute myeloid leukemia in Japanese children and adolescents

BACKGROUND

The relative efficacy of allogeneic hematopoietic cell transplantation (allo-HCT) after reduced toxicity conditioning (RTC) compared with standard myeloablative conditioning (MAC) in pediatric patients with acute myeloid leukemia (AML) has not been studied extensively. To address whether RTC is a feasible approach for pediatric patients with AML in remission, we performed a retrospective investigation of the outcomes of the first transplant in patients who had received an allo-HCT after RTC or standard MAC, using nationwide registration data collected between 2000 and 2011 in Japan.

PROCEDURE

We compared a fludarabine (Flu) and melphalan (Mel)-based regimen (RTC; n = 34) with total body irradiation (TBI) and/or busulfan (Bu)-based conditioning (MAC; n = 102) in demographic- and disease-criteria-matched childhood and adolescent patients with AML in first or second complete remission (CR1/CR2).

RESULTS

The incidence of engraftment, early complications, grade II-IV acute graft-versus-host disease (GVHD), and chronic GVHD were similar in each conditioning group. The risk of relapse (25% vs. 26%) and non-relapse mortality (13% vs. 11%) after 3 years did not differ between these groups, and univariate and multivariate analyses demonstrated that the 3-year overall survival (OS) rates after Flu/Mel-RTC and MAC were comparable (mean, 72% [range, 51-85%] and 68% [range, 58-77%], respectively).

CONCLUSIONS

The results suggest that the Flu/Mel-RTC regimen is a clinically acceptable conditioning strategy for childhood and adolescent patients with AML in remission. Although this retrospective, registry-based analysis has several limitations, RTC deserves to be further investigated in prospective trials.

Hematopoietic cell transplantation and cellular therapeutics in the treatment of childhood malignancies

Hematopoietic cell transplantation (HCT) represents the most common and effective form of immunotherapy for childhood malignancies. The role of the graft-versus-leukemia effect in allogeneic HCT has been well established in childhood malignancies, but is also associated with short-term and long-term morbidity. HCT may be ineffective in some settings at obtaining control of the malignancy, and as such, cannot be used as a universal cancer immunotherapy. Novel therapies using dendritic cell vaccinations, tumor-infiltrating lymphocytes, and chimeric antigen receptor T cells are being evaluated as potential adjuvants to HCT.

Reduced-toxicity myeloablative conditioning consisting of 8-Gy total body irradiation, cyclophosphamide and fludarabine for pediatric hematological malignancies

Conventional myeloablative conditioning (MAC) regimens often cause severe regimen-related toxicity (RRT). Furthermore, many patients suffer from poor quality of life in accordance with the increase in long-term survivors. We therefore devised a reduced-toxicity myeloablative conditioning (RTMAC) regimen consisting of 8-Gy total body irradiation (TBI), fludarabine (FLU) and cyclophosphamide (CY) for pediatric hematological malignancies. A retrospective single-center analysis was performed on patients with leukemia or myelodysplastic syndrome (MDS), aged ≤20 years, who had received an 8-Gy TBI/FLU/CY RTMAC regimen followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Thirty-one patients underwent first allo-HSCT after an RTMAC regimen. The diagnoses were acute lymphoblastic leukemia (n = 11), acute myeloid leukemia (n = 13), MDS (n = 4), juvenile myelomonocytic leukemia (n = 1) and acute leukemias of ambiguous lineage (n = 2). While 3 patients showed early hematological relapse, the remaining 28 patients achieved engraftments. None of the patients developed grade 4 or 5 toxicities during the study period. The 5-year overall survival and relapse-free survival were 80% [95% confidence interval: CI, 61-91%] and 71% [95% CI, 52-84%], respectively. Our RTMAC regimen would be less toxic and offers a high probability of survival for children with hematological malignancies.

Hematopoietic stem cell transplantation in adolescents and young adults

BACKGROUND

Adolescents and young adults (AYAs) are a very unique subset of our population journeying through a dynamic stage of their lives. This age group often remains understudied as a separate entity because they are commonly lumped into either pediatric or adult subgroups.

METHODS

Here we review acute and chronic issues surrounding hematopoietic stem cell transplantation (HSCT) with a focus on the AYA age group.

RESULTS

HSCT is a commonly used treatment modality for patients with certain types of cancers. AYA patients undergoing HSCT present a very unique perspective, circumstances, medical, psychological and social issues requiring a diligent workup, care and follow-up.

CONCLUSION

The medical care of these patients should be approached in a multidisciplinary method involving the patient, caregivers, physicians, psychologists and social workers.

Fludarabine, cytarabine, granulocyte colony-stimulating factor and melphalan (FALG with L-PAM) as a reduced toxicity conditioning regimen in children with acute leukemia

BACKGROUND

The conventional conditioning regimen for patients with leukemia prior to allogeneic stem cell transplantation is myeloablation to eradicate residual leukemic cells and host immunocompetent cells. This helps prevent leukemic relapse as well as rejection after transplantation. A myeloablative conditioning regimen with busulfan (BU) or total body irradiation (TBI) is effective for eradication of leukemic cells but is also associated with significant toxicities in the acute or late phase in pediatric patients. In an effort to minimize these adverse effects, we conducted bone marrow transplantation (BMT) from unrelated volunteer donors using a conditioning regimen without BU or TBI.

PROCEDURE

Ten patients with acute leukemia in first or second remission were given a "non-BU, non-TBI conditioning regimen," which consisted of fludarabine (FLU), cytarabine (CA), and melphalan (L-PAM) after FLAG combined with L-PAM.

RESULTS

Engraftment was obtained in all patients, and two patients died of relapse. Eight of 10 patients have been disease-free for a median of 126 months (116-142) after transplantation. The overall survival, event-free survival, relapse rate, and treatment-related mortality were 80.0%, 80.0%, 20.0% and 0.0%, respectively. In female patients, spontaneous menstruation with normal luteinizing hormone (LH), follicle stimulating hormone (FSH), and estradiol (E2) levels was observed in all four patients at post-pubertal age.

CONCLUSIONS

This conditioning regimen of FLAG combined with L-PAM (which did not contain BU and TBI) was associated with good outcomes and minimal late adverse effects in children with acute leukemia who have undergone allogeneic BMT from unrelated volunteer donors.

Transplantation for children with acute myeloid leukemia: a comparison of outcomes with reduced intensity and myeloablative regimens

The safety and efficacy of reduced-intensity conditioning (RIC) regimens for the treatment of pediatric acute myeloid leukemia is unknown. We compared the outcome of allogeneic hematopoietic cell transplantation in children with acute myeloid leukemia using RIC regimens with those receiving myeloablative-conditioning (MAC) regimens. A total of 180 patients were evaluated (39 with RIC and 141 with MAC regimens). Results of univariate and multivariate analysis showed no significant differences in the rates of acute and chronic graft-versus-host disease, leukemia-free, and overall survival between treatment groups. The 5-year probabilities of overall survival with RIC and MAC regimens were 45% and 48%, respectively (P = .99). Moreover, relapse rates were not higher with RIC compared with MAC regimens (39% vs 39%; P = .95), and recipients of MAC regimens were not at higher risk for transplant-related mortality compared with recipients of RIC regimens (16% vs 16%; P = .73). After carefully controlled analyses, we found that in this relatively modest study population, the data supported a role for RIC regimens for acute myeloid leukemia in children undergoing allogeneic hematopoietic cell transplantation. The data also provided justification for designing a carefully controlled randomized clinical trial that examines the efficacy of regimen intensity in this population.

Determination of intracellular fludarabine triphosphate in human peripheral blood mononuclear cells by LC-MS/MS

Fludarabine is a nucleoside analog routinely used in conditioning regimens of pediatric allogeneic stem cell transplantation to promote stem cell engraftment. In children, it remains a challenge to accurately and precisely quantify the active intracellular triphosphate species of fludarabine in vivo, primarily due to limitations on blood volume and inadequate assay sensitivity. Here we report a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for determination of fludarabine triphosphate in human peripheral blood mononuclear cells (PBMC). PBMC (∼5 million cells) were collected and lysed in 1mL 70% methanol containing 1.2mM tris buffer (pH 7.4). The lysate (80μL) was mixed with internal standard (2-chloro-adenosine triphosphate, 150ng/mL, 20μL) and injected onto an API5000 LC-MS/MS system. Separation was achieved on a hypercarb column (100mm×2.1mm, 3μm) eluted with 100mM ammonium acetate (pH 9.8) and acetonitrile in a gradient mode at a flow rate of 0.4mL/min. Multiple reactions monitoring (MRM) and electrospray ionization in negative mode (ESI(-)) were used for detection. The ion pairs 524.0/158.6 for the drug and 540.0/158.8 for the IS were selected for quantification and 524.0/425.7 used for confirmation. Retention time was 3.0 and 3.4min for fludarabine triphosphate and the IS, respectively. The concentration range for the calibration curve was 1.52-76nM. Our method is simple, fast, and has been successfully applied in a clinical dose-concentration study in children to quantify intracellular fludarabine in low volume clinical samples. The median concentration was 1.03 and 3.19pmole/million PBMC at trough and peak time points, respectively. Fludarabine triphosphate is degraded in water within hours but relatively stable in 70% methanol-tris (1.2mM, pH 7.4). One limitation is that the hypercarb column takes a longer time to equilibrate than conventional reverse phase columns, and peaks become broad and distorted if the column is not washed and stored properly.

Reduced-intensity conditioning followed by allogeneic transplantation in pediatric malignancies: a report from the Société Française des Cancers de l'Enfant and the Société Française de Greffe de Moelle et de Thérapie Cellulaire

We report French prospective experience with reduced-intensity conditioning-allo-SCT in 46 patients (median age: 15.5 years, 4.8-20.2) presenting high-risk AL (n=11), Hodgkin's lymphoma (n=15) or solid tumors (n=20). Graft sources were BM (n=21), PBSC (n=20) and cord blood (CB; n=5) from related (n=20) or unrelated (n=26) donors. For CB grafts, only one patient out of five achieved sustained engraftment. For PBSC/BM grafts, engraftment rate was 95%, hematopoietic recovery times were not significantly different between BM, PBSC, sibling or unrelated grafts, day+100. Full donor chimerism was achieved in 94% of patients, and incidences of primary acute GVHD and chronic GVHD were 49% and 14%, respectively. Underlying disease was fatal in 39% of patients. TRM was 6.9%. Three-year OS was 49.15%. OS and EFS were not significantly different between patients transplanted with different grafts and with or without primary GVHD. Patients with solid tumor or measurable disease at transplant had poorer outcomes. Three-year EFS: 33.3% for ALL, 75.0% for AML, 51.8% for Hodgkin's lymphoma, 28.6% for neuroblastoma and 22.2% for sarcoma patients. This multicentre study concluded that Bu/fludarabine/anti-thymocyte globulin conditioning with PB or BM, related or unrelated grafts in patients with various malignancies at high-risk for transplantation toxicity results in high engraftment rates, low TRM and acceptable survival.

Leukemia cell-rhabdovirus vaccine: personalized immunotherapy for acute lymphoblastic leukemia

PURPOSE

Acute lymphoblastic leukemia (ALL) remains incurable in most adults. It has been difficult to provide effective immunotherapy to improve outcomes for the majority of patients. Rhabdoviruses induce strong antiviral immune responses. We hypothesized that mice administered ex vivo rhabdovirus-infected ALL cells [immunotherapy by leukemia-oncotropic virus (iLOV)] would develop robust antileukemic immune responses capable of controlling ALL.

EXPERIMENTAL DESIGN

Viral protein production, replication, and cytopathy were measured in human and murine ALL cells exposed to attenuated rhabdovirus. Survival following injection of graded amounts of ALL cells was compared between cohorts of mice administered γ-irradiated rhabdovirus-infected ALL cells (iLOV) or multiple control vaccines to determine key immunotherapeutic components and characteristics. Host immune requirements were assessed in immunodeficient and bone marrow-transplanted mice or by adoptive splenocyte transfer from immunized donors. Antileukemic immune memory was ascertained by second leukemic challenge in long-term survivors.

RESULTS

Human and murine ALL cells were infected and killed by rhabdovirus; this produced a potent antileukemia vaccine. iLOV protected mice from otherwise lethal ALL by developing durable leukemia-specific immune-mediated responses (P < 0.0001), which required an intact CTL compartment. Preexisting antiviral immunity augmented iLOV potency. Splenocytes from iLOV-vaccinated donors protected 60% of naïve recipients from ALL challenge (P = 0.0001). Injecting leukemia cells activated by, or concurrent with, multiple Toll-like receptor agonists could not reproduce the protective effect of iLOV. Similarly, injecting uninfected irradiated viable, apoptotic, or necrotic leukemia cells with/without concurrent rhabdovirus administration was ineffective.

CONCLUSION

Rhabdovirus-infected leukemia cells can be used to produce a vaccine that induces robust specific immunity against aggressive leukemia.

Transplantation conditioning regimens and outcomes after allogeneic hematopoietic cell transplantation in children and adolescents with acute lymphoblastic leukemia

Relapse is common after hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL). Although 1200 cGy total body irradiation (TBI) and cyclophosphamide (Cy) is the standard conditioning regimen, attempts to reduce relapse have led to the addition of a second chemotherapeutic agent and/or higher dose of TBI. We examined HSCT outcomes in patients age <18 years with ALL, in second or subsequent remission or in relapse at transplantation. Most transplantations were performed with the patient in remission. Patients received grafts from an HLA-matched sibling or unrelated donor. Four treatment groups were created: (1) Cy + TBI ≤ 1200 cGy (n = 304), (2) Cy + etoposide + TBI ≤ 1200 cGy (n = 108), (3) Cy + TBI ≥ 1300 cGy (n = 327), and (4) Cy + etoposide + TBI ≥ 1300 cGy (n = 26). Neither TBI > 1200 cGy nor the addition of etoposide resulted in fewer relapses. The 5-year probability of relapse was 30% for group 1, 28% for group 2, 35% for group 3, and 31% for group 4. However, transplantation-related mortality was higher (35% versus 25%, P = .02) and overall survival lower (36% versus 48%, P = .03) in group 4 compared with group 3. Our findings indicate that compared with the standard regimen, neither TBI > 1200 cGy nor the addition of etoposide improves survival after HSCT for ALL.

Allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning regimen in children: a single-center experience

This single-center retrospective study reported the outcome of 19 children treated with a reduced-intensity conditioning (RIC) regimen prior to allogeneic stem cell transplantation (allo-SCT), for hematologic malignancies (n = 17), bone marrow failure (n = 1), and neuroblastoma (n = 1). Children were ineligible for standard myeloablative conditioning because of severe comorbidities (n = 9), a previous auto or allo-SCT (n = 7) or a prior history of extensive chemotherapy (n = 3). All patients underwent a fludarabine-based RIC regimen, and received grafts from matched-related donors (n = 5), match-unrelated donors (n = 6), or unrelated cord blood (UCB, n = 8). In this series, two patients treated with UCB failed to engraft and 63% achieved full donor chimerism at day 100 after allo-SCT. With a median follow-up of 537 d (range, 115-4136), treatment-related mortality was 16% and overall survival was 47%. The principal cause of death was disease relapse (n = 7). Acute graft versus host disease (GVHD) occurred in 53% of patients, while only 10% developed extensive chronic GVHD. Overall, results from this series suggest that RIC allo-SCT can be a valid alternative treatment option in unfit children with malignant hematological diseases. Prospective studies are needed to enlarge pediatric experience in this domain and better identify those children more suitable for a RIC allo-SCT approach.

Role of cytotoxic therapy with hematopoietic stem cell transplantation in the treatment of pediatric acute lymphoblastic leukemia: update of the 2005 evidence-based review

Clinical research published since the first evidence-based review on the role of hematopoietic stem cell transplantation (SCT) in the treatment of pediatric acute lymphoblastic leukemia (ALL) is presented and critically evaluated in this update. Treatment recommendations are provided by an expert panel. Allogeneic SCT is recommended for children who: are in second complete remission (CR2) after experiencing an early marrow relapse for precursor-B ALL; experienced primary induction failure, but subsequently achieved a CR1; have T-lineage ALL in CR2; or have ALL in third or greater remission. Although the 2005 pediatric ALL evidence-based review (EBR) recommended allogeneic SCT for children with Philadelphia chromosome positive (Ph+) ALL in CR1, preliminary tyrosine kinase inhibitor (TKI) data demonstrate that early outcomes are comparable for allogeneic SCT and chemotherapy + imatinib. Based on the evidence, autologous SCT is not recommended for ALL in CR1. Allogeneic SCT is not recommended for: T-lineage ALL in CR1; mixed-lineage leukemia (MLL)+ ALL when it is the sole adverse risk factor; isolated central nervous system (CNS) relapse in precursor-B ALL. Based on expert opinion, allogeneic SCT may be considered for hypodiploid ALL and persistent minimal residual disease [corrected] (MRD) positivity in ALL in CR1 or greater, although these are areas that need further study. Treatment recommendations pertaining to various transplantation techniques are also provided, as are areas of needed future research.

Outcome of myeloablative conditioning and unrelated donor hematopoietic cell transplantation for childhood acute lymphoblastic leukemia in third remission

We conducted a retrospective study of 155 children who underwent unrelated donor hematopoietic cell transplantation (HCT) between 1990 and 2005 for acute lymphoblastic leukemia in third remission. The median patient age was 11 years, the median time from diagnosis to first relapse was 36 months, and the median time from first relapse to second relapse was 26 months. Stem cell sources were bone marrow (n = 115), peripheral blood (n = 11), and cord blood (n = 29). All patients received a myeloablative pretransplantation conditioning regimen. The 5-year estimates of leukemia-free survival, relapse, and nonrelapse mortality were 30%, 25%, and 45%, respectively. In multivariate analysis, the only risk factor associated with relapse was the interval between the first relapse and the second relapse. Second relapses occurring >26 months from the first relapse were associated with lower risk for post-HCT relapse compared with second relapses occurring at ≤26 months (relative risk, 0.4; P = .01). Relapse risk was lowest when late second relapse was preceded by late first relapse (>36 months from diagnosis), as demonstrated by a 3-year relapse rate of 9% (P = .0009). Our data indicate that long-term leukemia-free survival can be achieved in children with acute lymphoblastic leukemia in third remission using unrelated donor HCT, especially when the second relapse occurs late.

[Reduced intensity allogenic hematopoietic stem cell transplantation in children]

Better understanding of the antitumor effect of allogeneic transplant and the need to reduce the toxicity of the procedure, particularly in elderly patients have spurred the development of reduced-intensity conditioning regimens (RIC). These regimens allow fast engraftment with very low chemotherapy-induced toxicity. They are widely used in adults and there are numerous studies to demonstrate their feasibility and efficiency, but in pediatrics, the place of RIC remains to be determined. They can be proposed in two pediatric populations. First, solid tumors or hematological malignancies remaining unresponsive to the reference strategies according to best practices in pediatrics. Second, in children presenting malignancies for which allografting is the only recognized curative indication but is contraindicated with myeloablative conditioning regimens. More than 100 pediatrics cases have been reported in various pathologies, including blood diseases, acute leukemia, Hodgkin's lymphoma and solid tumors, and promising results published recently underline how RIC warrants further investigation in prospective comparative multicentric trials. The use of new post-graft treatment modalities is expected to pave the way to the development of RIC in pediatric patients.

Pediatric Acute Lymphoblastic Leukemia: Is There Still a Role for Transplant?

Constant questioning of the applicability of transplant for any diagnosis is appropriate. This is particularly necessary in fields such as pediatric leukemia, in which significant progress in therapy and risk classification is being made. Outcomes with chemotherapy are constantly improving, and donor availability and transplant outcomes are also better. It is important to be aware of likely outcomes when counseling families and recommending therapy, and to consider issues of likely late side effects. Biological studies that predict prognosis, for example, array-based studies, hold hope of identifying the children destined to relapse at the outset of disease. However, a rigorous approach must be taken in determining whether transplant does improve outcome whenever this strategy is applied.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT.