Second allogeneic bone marrow transplantation for post-transplant leukemia relapse: results of a survey of 66 cases in 24 Japanese institutes

Post-Hematopoietic Cell Transplantation Relapsed Acute Lymphoblastic Leukemia: Current Challenges and Future Directions

Allogeneic hematopoietic cell transplantation (allo-HCT) represents an important and potentially curative treatment option for adult patients with acute lymphoblastic leukemia. Relapse continues to remain the most important factor influencing overall survival post allo-HCT. We discuss early identification, clinical manifestations, and management of relapsed disease. Routine evaluation of measurable residual disease (MRD) and change in donor chimerism play a crucial role in early detection. Pivotal clinical trials have led to FDA approval of multiple novel agents like blinatumomab and inotuzumab. Combining targeted therapy with cellular immunotherapy serves as the backbone for prolonging overall survival in these patients. Donor lymphocyte infusions have traditionally been used in relapsed disease with suboptimal outcomes. This review provides insight into use of cellular therapy in MRD positivity and decreasing donor chimerism. It also discusses various modalities of combining cellular therapy with novel agents and discussing the impact of chimeric antigen receptor T-cell therapy in the setting of post allo-HCT relapse both as consolidative therapy and as a bridge to second transplant.

Outcomes in patients with acute lymphoblastic leukemia who underwent second allogeneic hematopoietic cell transplantation for relapse after first transplantation

Outcomes in patients with acute lymphoblastic leukemia (ALL) who experience relapse after allogeneic hematopoietic cell transplantation (HCT) are unsatisfactory. This study aimed to evaluate the outcomes of patients with ALL who underwent second HCT (HCT2) for relapse after first HCT. It was a single-center retrospective study including adult patients with ALL who underwent HCT2 between 1991 and 2020. The cohort was stratified according to the transplant year, and included 39 patients with a median age of 29 years. A more recent transplant year was associated with achievement of complete remission (CR) and use of reduced-intensity conditioning (RIC), compared with an earlier transplant year. The overall survival (OS) rate and 2-year cumulative incidence of non-relapse mortality (recent vs. earlier) were 55% vs. 8% (P < 0.001) and 26% vs. 75% (P < 0.001), respectively. In multivariate analysis, non-CR (vs. CR; HR 3.6, 95% CI 1.2-11.3, P = 0.025) and myeloablative conditioning (vs. RIC; HR 3.5, 95% CI 1.3-9.4, P = 0.011) were negative prognostic factors for OS. Outcomes of the recent cohort from real-world data are promising, and achieving CR and using the RIC regimen at HCT2 may be an important therapeutic strategy.

Second unmanipulated allogeneic transplantation could be used as a salvage option for patients with relapsed acute leukemia post-chemotherapy plus modified donor lymphocyte infusion

Relapse is the main problem after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The outcome of a second allo-HSCT (HSCT2) for relapse post-HSCT has shown promising results in some previous studies. However, little is known about the efficacy of HSCT2 in patients with relapsed/refractory acute leukemia (AL) post-chemotherapy plus modified donor lymphocyte infusion (post-Chemo + m-DLI) after the first allo-HSCT (HSCT1). Therefore, we retrospectively analyzed the efficacy of HSCT2 in 28 patients with relapsed/refractory AL post-Chemo + m-DLI in our center. With a median follow-up of 918 (457-1732) days, 26 patients (92.9%) achieved complete remission, and 2 patients exhibited persistent disease. The probabilities of overall survival (OS) and disease-free survival (DFS) 1 year after HSCT2 were 25.0% and 21.4%, respectively. The cumulative incidences of nonrelapse mortality on day 100 and at 1 year post-HSCT2 were 7.1% ± 4.9% and 25.0% ± 8.4%. The cumulative incidences of relapse were 50.0% ± 9.8% and 53.5% ± 9.9% at 1 and 2 years post-HSCT2, respectively. Risk stratification prior to HSCT1 and percentage of blasts before HSCT2 were independent risk factors for OS post-HSCT2, and relapse within 6 months post-HSCT1 was an independent risk factor for DFS and relapse post-HSCT2. Our findings suggest that HSCT2 could be a salvage option for patients with relapsed AL post-Chemo + m-DLI.

Second allogeneic transplants for multiple myeloma: a report from the EBMT Chronic Malignancies Working Party

The EBMT Chronic Malignancies Working Party performed a retrospective analysis of 215 patients who underwent a second allo-HCT for myeloma between 1994 and 2017, 159 for relapse and 56 for graft failure. In the relapse group, overall survival (OS) was 38% (30–46%) at 2 years and 25% (17–32%) at 5 years. Patients who had a HLA-identical sibling (HLAid-Sib) donor for their first and second transplants had superior OS (5 year OS: HLAid-Sib/HLAid-Sib: 35% (24–46%); Others 9% (0–17%), p < 0.001). There was a significantly higher incidence of acute grade II-IV GvHD in those patients who had also developed GvHD following their initial HLA-identical sibling allo-HCT (HLAid-Sib/HLAid-Sib: 50% (33–67%); Other 22% (8–36%), p = 0.03). More as opposed to fewer than 2 years between transplants was associated with superior 5-yr OS (31% (21–40%) vs. 10% (1–20%), P = 0.005). On multivariate analysis, consecutive HLA-identical sibling donor transplants conferred a significant OS advantage (0.4 (0.24–0.67), p < 0.001). In the graft failure group, OS was 41% at 2 years. In summary, a second allo-HCT using a HLA-identical sibling donor, if available, provides the best transplant outcomes for relapsed myeloma in this setting.

Outcome predictors after retransplantation in relapsed acute lymphoblastic leukemia: a multicenter, retrospective study

Retransplantation is the only curative treatment option for patients with acute lymphoblastic leukemia (ALL) that has relapsed after allogeneic hematopoietic cell transplantation (allo-HCT); however, data in this setting remain scant. Hence, this multicenter, retrospective study aims to determine outcome predictors after retransplantation in relapsed ALL. We examined 55 recipients who underwent multiple allo-HCTs during 2006-2018. The 2-year overall survival (OS), progression-free survival (PFS), and non-relapse mortality rates were 35.9%, 29.1%, and 23.6%, respectively. We observed a trend of better outcome in Ph + ALL (n = 22) patients compared with non-Ph ALL (n = 33) patients; the 2-year PFS was 40.9% versus 21.2%, indicating a beneficial effect of more potent second- or third-generation tyrosine kinase inhibitors. Univariate analysis revealed that late relapse after the previous transplant was the only significant predictor of better transplant outcome among Ph + ALL patients, whereas factors related to prolonged OS/PFS in non-Ph ALL patients were late relapse after the previous transplant, longer duration from disease relapse/progression to second or more allo-HCT, disease status at the transplantation, and good performance status. Nevertheless, further investigations are warranted to determine whether novel molecular-targeted agents with higher efficacy and fewer toxicities could exceed conventional chemotherapies as a bridging strategy to next allo-HCT and improve the outcomes of non-Ph ALL patients.

Geriatric nutritional risk index as a useful prognostic factor in second allogeneic hematopoietic stem cell transplantation

Second allogeneic hematopoietic stem cell transplantation (allo-HSCT) has a low survival outcome and a high non-relapse mortality (NRM) rate which is a major obstacle to this treatment. We hypothesized that the status of malnourishment after first allo-HSCT as represented by the geriatric nutritional risk index (GNRI) could be used as a prognostic factor to determine the outcomes of second allo-HSCT. A total of 108 patients with a median age of 42 (range, 17-69) years, who received second allo-HSCT for disease recurrence after first allo-HSCT from our institution, were included in this study. Low GNRI had a significant impact on NRM at 2 years after second allo-HSCT: 56.9% in patients with GNRI ≤ 92 compared with 27.5% in patients with GNRI > 92 (P = 0.002). In multivariate analysis, GNRI of ≤ 92 was the only significant factor for NRM (hazard ratio [HR] 2.29, 95% confidence interval [CI] 1.15-4.56, P = 0.018). High-risk disease status at second allo-HSCT (HR 2.74, 95% CI 1.46-5.14, P = 0.002) and GNRI of ≤ 92 (HR 1.70, 95% CI 1.02-2.82, P = 0.042) were identified as significant factors for overall survival (OS). A score of 1 was assigned to each factor, and the OS rate at 2 years after second allo-HSCT decreased according to the score: 53.0% in patients with score 0, 32.3% with score 1, and 2.5% with score 2 (P < 0.001). In conclusion, GNRI could be a useful predictor for the outcomes of second allo-HSCT. A prospective study in other cohorts is warranted to validate the findings of our study.

Haploidentical Donor Transplantation Using a Novel Clofarabine-containing Conditioning Regimen for Very High-risk Hematologic Malignant Neoplasms

Recurrent/refractory hematologic malignancies have a poor prognosis, and there is a need for novel treatment regimens that can be tolerated by this heavily pretreated patient group. Clofarabine has antileukemic activity with an acceptable toxicity profile. In a phase I clinical trial (NCT00824135), we substituted clofarabine for fludarabine in a well-established reduced-intensity conditioning regimen for a T cell-depleted, mismatched-related (haploidentical) donor transplant backbone and explored the maximum tolerated dose of clofarabine in this combination in 15 patients undergoing hematopoietic cell transplantation for recurrent/refractory or secondary leukemia. Clofarabine was well tolerated at a dose of 50 mg/m/d for 5 days in this regimen, with minimal treatment-related mortality in a heavily pretreated group of high-risk patients. All patients exhibited quick hematopoietic recovery, with median times to neutrophil and platelet engraftment being 11 and 16 days, respectively. Transient elevation of transaminases was the most common toxicity-observed in 13 patients (86.7%), with 6 (40%) grade III or above. Three patients (20%) developed hepatic veno-occlusive disease. Eleven patients (73.3%) died, with the most common cause of death being disease relapse (in 9 patients [60%]), followed by treatment-related mortality (in 2 patients [13.3%]). Four (26.6%) of the patients are long-term survivors.

Prevention and treatment of relapse after stem cell transplantation by cellular therapies

Despite recent advances in reducing therapy-related mortality after allogeneic stem cell transplantation (alloSCT) relapse remains the major cause of treatment failure and little progress has been achieved in the last decades. At the 3rd International Workshop on Biology, Prevention, and Treatment of Relapse held in Hamburg/Germany in November 2016 international experts presented and discussed recent developments in the field. Here, the potential of cellular therapies including unspecific and specific T cells, genetically modified T cells, CAR-T cells, NK-cells, and second allografting in prevention and treatment of relapse after alloSCT are summarized.

Outcome of Second Allogeneic Hematopoietic Cell Transplantation in Patients With Acute Lymphoblastic Leukemia

BACKGROUND

The outcome of patients with acute lymphoblastic leukemia (ALL) relapsing after allogeneic hematopoietic cell transplantation (AlloHCT) is poor. Although morphologic remission can sometimes be achieved, such remissions are usually transient if not consolidated by a second AlloHCT (AlloHCT2).

MATERIALS AND METHODS

We retrospectively analyzed the outcomes of 27 patients with ALL who had undergone AlloHCT2 for relapsed disease at our center during a 12-year period.

RESULTS

With a median follow-up of 50.9 months for living patients, the 2-year overall and event-free survival were 40.7% and 29.6%, respectively. Patients with either a disease-free interval or interval between transplants of > 1 year had better overall survival (P = .02 and P = .0005) after AlloHCT2.

CONCLUSION

AlloHCT2 remains a potential curative option in a subset of patients with relapsed ALL after the first AlloHCT.

Second Allogeneic Stem Cell Transplantation for Acute Leukemia Using a Chemotherapy-Only Cytoreduction with Clofarabine, Melphalan, and Thiotepa

Relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) remains one of the leading causes of mortality in patients with leukemia. Treatment options in this population remain limited, with concern for both increased toxicity and further relapse. We treated 18 patients with acute leukemia for marrow ± extramedullary relapse after a previous alloHSCT with a myeloablative cytoreductive regimen including clofarabine, melphalan, and thiotepa followed by a second or third transplantation from the same or a different donor. All patients were in remission at the time of the second or third transplantation. All evaluable patients engrafted. The most common toxicity was reversible transaminitis associated with clofarabine. Two patients died from transplantation-related causes. Seven patients relapsed after their second or third transplanation and died of disease. Nine of 18 patients are alive and disease free, with a 3-year 49% probability of overall survival (OS). Patients whose remission duration after initial alloHSCT was >6 months achieved superior outcomes (3-year OS, 74%, 95% confidence interval, 53% to 100%), compared with those relapsing within 6 months (0%) (P < .001). This new cytoreductive regimen has yielded promising results with acceptable toxicity for second or third transplantations in patients with high-risk acute leukemia who relapsed after a prior transplantation, using various graft and donor options. This approach merits further evaluation in collaborative group studies.

Second allogeneic transplantation for relapse of malignant disease: retrospective analysis of outcome and predictive factors by the EBMT

In patients treated with allogeneic stem cell transplantation (SCT) for malignant disease who suffer from a relapse after the transplantation, the role of second allogeneic SCT is often uncertain. In a retrospective analysis, 2632 second allogeneic transplantations carried out for a relapse after the first transplantation were analyzed to define indications and identify predictive factors. Fifteen percent of the patients remained relapse-free until 5 years after the second SCT. Patients with CML had a better survival than patients with other diseases. In a multivariate analysis, factors associated with better survival were low disease burden, longer remission duration after the first transplantation, longer interval between the transplantations, younger age, absence of grade II-IV acute GvHD or chronic GvHD after the first transplantation, and later year of transplantation. The European Society for Blood and Marrow Transplantation risk score predicted the outcome. Using the same donor as in the first transplantation vs another donor had no predictive value for survival. Sibling donor was a favorable predictive factor. In conclusion, second allogeneic SCT offers a reasonable option especially for young patients with a long remission after the first transplantation and a low disease burden. The present findings do not support the usefulness of changing the donor for the second transplantation.

Second allogeneic transplantation using unrelated cord blood for relapsed hematological malignancies after allogeneic transplantation

The efficacy of second allogeneic stem cell transplantation (SCT2) using cord blood (CB) for patients with relapsed hematological malignancies after initial allogeneic stem cell transplantation (SCT1) is unknown. We analyzed the results of SCT2 using single-unit unrelated CB in 34 adult patients with relapsed hematological malignancies after SCT1 in our institution. The patients had acute myeloid leukemia (n = 23), acute lymphoblastic leukemia (n = 7), chronic myelogenous leukemia (n = 2), and myelodysplastic syndrome (n = 2). The cumulative incidence of neutrophil and platelet engraftment was 81.6% at 30 days and 68.5% at 100 days, respectively. With a median follow-up of 40 months, the probability of overall survival at 3 years was 29.0%. The cumulative incidence of relapse and transplant-related mortality at 3 years were 60.7% and 27.2%, respectively. The use of CB could offer the opportunity to receive SCT2 for patients who experienced disease relapse after SCT1 without HLA-identical related or unrelated donors.

Outcomes after Second Hematopoietic Stem Cell Transplantations in Pediatric Patients with Relapsed Hematological Malignancies

Relapse of hematological malignancies after hematopoietic stem cell transplantation (HCT) is associated with poor prognosis. A second HCT represents one of the few therapeutic options for these high-risk patients. For children undergoing second HCT, the outcome data are particularly limited. We, therefore, conducted a retrospective single-institution study and report the outcomes and prognostic variables associated with overall survival (OS) and relapse in 43 pediatric patients who underwent a second HCT between 2000 and 2013. Eleven of the 43 patients who underwent transplantation remain alive and disease-free at a median follow-up of 49 months (range, 5 to 127 months). The 5-year probability of OS for the entire cohort was 24%. Patients who had early relapse (<6 months) after first HCT had significantly worse OS than those who relapsed late (>6 months), with 5-year OS at 11% versus 34%, respectively (hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.21 to 4.93; P = .013). Active disease at time of second HCT was also associated with a significantly increased risk of relapse (subdistribution hazard ratio [SHR], 2.36; P = .049) for the entire cohort and relapse was the most frequent cause of death (23 of 32; 72%). On subgroup analysis for the 34 patients with leukemia alone, presence of active disease was associated both with a significant decrease in OS (SHR, 2.28; 95% CI, 1.02 to 5.09; P = .044) and significant increase in the rate of relapse (SHR, 2.46; P = .046). By contrast, underlying disease, donor source, conditioning regimen, or development of GVHD did not modify OS or rate of relapse. Hence, a second HCT appears to be a useful therapeutic option in children with relapsed hematological malignancies that is most likely to benefit those individuals with late onset of relapse and with low disease burden at the time of transplantation.

Treatment of relapse of acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation

Disease relapse remains a major cause of mortality for patients with acute myeloid leukemia (AML) undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Historically, patients who experience disease relapse after HSCT have a dismal prognosis with very few long-term survivors. There is no standard treatment for patients in this situation given the variability in patient characteristics, disease biology, complications such as graft-vs.-host disease (GVHD) and infections, donor availability, and patient choice. Here, we discuss the current options for treatment of relapsed AML after HSCT including conventional chemotherapy, novel agents, donor leukocyte infusion, second allogeneic HSCT, and emerging therapies.

Long-term survival and late effects among one-year survivors of second allogeneic hematopoietic cell transplantation for relapsed acute leukemia and myelodysplastic syndromes

We analyzed the outcomes of patients who survived disease-free for 1 year or more after a second allogeneic hematopoietic cell transplantation (HCT) for relapsed acute leukemia or myelodysplastic syndromes between 1980 and 2009. A total of 1285 patients received a second allogeneic transplant after disease relapse; among these, 325 were relapse free at 1 year after the second HCT. The median time from first to second HCT was 17 and 24 months for children and adults, respectively. A myeloablative preparative regimen was used in the second transplantation in 62% of children and 45% of adult patients. The overall 10-year conditional survival rates after second transplantation in this cohort of patients who had survived disease-free for at least 1 year was 55% in children and 39% in adults. Relapse was the leading cause of mortality (77% and 54% of deaths in children and adults, respectively). In multivariate analyses, only disease status before second HCT was significantly associated with higher risk for overall mortality (hazard ratio, 1.71 for patients with disease not in complete remission before second HCT, P < .01). Chronic graft-versus-host disease (GVHD) developed in 43% and 75% of children and adults after second transplantation. Chronic GVHD was the leading cause of nonrelapse mortality, followed by organ failure and infection. The cumulative incidence of developing at least 1 of the studied late effects within 10 years after second HCT was 63% in children and 55% in adults. The most frequent late effects in children were growth disturbance (10-year cumulative incidence, 22%) and cataracts (20%); in adults they were cataracts (20%) and avascular necrosis (13%). Among patients with acute leukemia and myelodysplastic syndromes who receive a second allogeneic HCT for relapse and survive disease free for at least 1 year, many can be expected to survive long term. However, they continue to be at risk for relapse and nonrelapse morbidity and mortality. Novel approaches are needed to minimize relapse risk and long-term transplantation morbidity in this population.

Second haematopoietic SCT using HLA-haploidentical donors in patients with relapse of acute leukaemia after a first allogeneic transplantation

Haploidentical haematopoietic SCT (HSCT) using T-cell-replete grafts and post-transplant high-dose CY has found increasing acceptance. Our purpose was to evaluate the feasibility and outcome of this strategy as second HSCT incorporating donor change for acute leukaemia relapse after a first allogeneic transplantation. The courses of 20 consecutive adults (median age 37 years, 12 male) with AML (n=14), ALL (n=5) and acute bi-phenotypic leukaemia (n=1) were analysed retrospectively. Conditioning consisted of fludarabine, CY and either melphalan or TBI or tresosulfan+/-etoposide. Engraftment was achieved in 17 (85%), and a second remission was induced in 15 patients (75%) on day +30. The rate of grade II-IV acute GvHD was 35%, while chronic GvHD occurred in five patients. Most commonly observed grade III-IV toxicities were mucositis (30%), hyperbilirubinemia (20%), elevation of transaminases (20%) and creatinine (20%), while invasive fungal infection affected 30%. One-year non-relapse mortality (NRM) was 36%. At a median follow-up of 17 months, estimated 1-year OS was 45%, and 1-year relapse-free survival was 33%. This strategy was feasible and allowed for successful engraftment with a moderate rate of toxicity. Early outcome and NRM are at least comparable with results after a second HSCT from HLA-matched donors without donor change at HSCT2.

Immunotherapy following relapse of acute leukaemia after T-cell-replete allogeneic peripheral blood progenitor cell transplantation: importance of new onset chronic graft-versus-host disease

INTRODUCTION

To further define the relative impact of immunotherapy and subsequent development of graft-versus-host disease (GVHD) on survival in patients with relapsed acute leukaemia postallogeneic hematopoietic stem cell transplant (SCT), we performed a single-centre retrospective analysis of 32 actively treated patients between 2003 and 2011.

METHODS

A total of 13 patients were identified who were treated actively with cessation of immunosuppression ± Fludarabine, Cytarabine, G-CSF (FLAG) induction, but no donor leucocyte infusion (DLI) (non-DLI group) and 19 patients received the same step-wise therapy plus G-CSF mobilized DLI (G-DLI group).

RESULTS

Groups were not statistically different with regards to baseline characteristics; however, the G-DLI group contained more sibling donors as opposed to unrelated donors than the non-DLI group. With a median follow-up of 47 months, the median overall survival (OS) of the non-DLI and G-DLI groups was not statistically different (8 months vs. 9 months, respectively, P = 0.5). Survival at 3 years was <10% in both groups. Univariate analysis identified response to FLAG, and new onset chronic GVHD as the only factors associated with improved OS.

CONCLUSION

Second donor stem cell infusions are unwarranted in the treatment of relapse after allogeneic SCT and therapeutic strategies should focus on cytoreduction followed by immune modulation with the aim of invoking chronic GVHD.

Second allograft for hematologic relapse of acute leukemia after first allogeneic stem-cell transplantation from related and unrelated donors: the role of donor change

PURPOSE

To evaluate the role of a second allogeneic hematopoietic stem-cell transplantation (HSCT2) given for relapsed acute leukemia (AL) after related or unrelated first hematopoietic stem-cell transplantation (HSCT1) and to analyze the role of donor change for HSCT2 in both settings.

PATIENTS AND METHODS

We performed a retrospective registry study on 179 HSCT2s given for relapse after HSCT1 from matched related donors (n = 75) or unrelated donors (n = 104), using identical or alternative donors for HSCT2. Separate analyses were performed according to donor at HSCT1.

RESULTS

Independent of donor, 74% of patients achieved complete remission after HSCT2, and half of these patients experienced relapse again. Overall survival (OS) at 2 years was 25% ± 4% (39% ± 7% after related HSCT2; 19% ± 4% after unrelated HSCT2). Long-term survivors were observed even after two unrelated HSCT2s. Multivariate analysis for OS from HSCT2 confirmed established risk factors (remission duration after HSCT1: hazard ratio [HR], 2.37; 95% CI, 1.61 to 3.46; P < .001; stage at HSCT2: HR, 0.53; 95% CI, 0.34 to 0.83; P = .006). Outcome of HSCT2 was better after related HSCT1 than after unrelated HSCT1 (2-year OS: 37% ± 6% v 16% ± 4%, respectively; HR, 0.68; 95% CI, 0.47 to 0.98; P = .042, multivariate Cox regression). After both related and unrelated HSCT1, selecting a new donor for HSCT2 did not result in a relevant improvement in OS compared with HSCT2 from the original donor; however, donor change was not detrimental either.

CONCLUSION

After relapse from allogeneic HSCT1, HSCT2 can induce 2-year OS in approximately 25% of patients. Unrelated HSCT2 is feasible after related and unrelated HSCT1. Donor change for HSCT2 is a valid option. However, a clear advantage in terms of OS could not be demonstrated.

Subsequent donation requests among 2472 unrelated hematopoietic progenitor cell donors are associated with bone marrow harvest

Approximately 1 in 20 unrelated donors are asked to make a second donation of hematopoietic progenitor cells, the majority for the same patient. Anthony Nolan undertook a study of subsequent hematopoietic progenitor cell donations made by its donors from 2005 to 2011, with the aims of predicting those donors more likely to be called for a second donation, assessing rates of serious adverse reactions and examining harvest yields. This was not a study of factors predictive of second allografts. During the study period 2591 donations were made, of which 120 (4.6%) were subsequent donations. The median time between donations was 179 days (range, 21-4016). Indications for a second allogeneic transplant included primary graft failure (11.7%), secondary graft failure (53.2%), relapse (30.6%) and others (1.8%). On multivariate analysis, bone marrow harvest at first donation was associated with subsequent donation requests (odds ratio 2.00, P=0.001). The rate of serious adverse reactions in donors making a subsequent donation appeared greater than the rate in those making a first donation (relative risk=3.29, P=0.005). Harvest yields per kilogram recipient body weight were equivalent between donations, although females appeared to have a lower yield at the subsequent donation. Knowledge of these factors will help unrelated donor registries to counsel their donors.

Outcomes of second allogeneic hematopoietic stem cell transplantation for patients with acute lymphoblastic leukemia

For patients with ALL who relapse following allo-SCT, only a second SCT provides a realistic chance for long-term disease remission. We retrospectively analyzed the outcomes of 31 patients with relapsed ALL after a prior allo-SCT, who received a second SCT (SCT2) at our center. With a median follow-up of 3 years, 1- and 3-year PFS was 23 and 11% and 1- and 3 year OS rates were 23 and 11%. Twelve patients (39%) were transplanted with active disease, of whom 75% attained a CR. We found a significant relationship between the time to treatment failure following first allograft (SCT1) and PFS following SCT2 (P=0.02, hazard ratio=0.93/month). In summary, a second transplant remains a potential treatment option for achieving response in a highly refractory patient population. While long-term survival is limited, a significant proportion of patients remains disease-free for up to 1 year following SCT2, providing a window of time to administer preventive interventions. Notably, our four long-term survivors received novel therapies with their second transplant underscoring the need for a fundamental change in the methods for SCT2 to improve outcome.

The second therapeutic trial for children with hematological malignancies who relapsed after their first allogeneic SCT: long-term outcomes

The impact of a second all-SCT on the long-term outcomes of children who relapse after allo-SCT has been unclear. We retrospectively analyzed the long-term outcomes of different salvage treatments for such children. Sixty-six children with hematological malignancies (40 ALL, 22 AML, three MDS, and one CML) who relapsed after a first allo-SCT received either a second allo-SCT (n = 16) or CTx and/or DLI (n = 50). The median follow-up for all children was 9.1 yr. The five-yr OS after relapse was significantly better in patients who underwent a second allo-SCT (42.9%) than in patients treated with CTx and/or DLI (11.8%) (p < 0.05). However, this advantage diminished with increasing time. The eight-yr OS for these groups of patients were 21.4% and 11.8%, respectively (p = n.s.). Among the 16 patients who received a second allo-SCT, two died more than five yr after the second allo-SCT. A second allo-SCT can therefore lead to a prolonged OS in patients who relapse after allo-SCT. However, a second allo-SCT should be selected carefully. This is because the mortality rate is still high, even when there is an extensive duration of time following the second allo-SCT.

Approaches to relapse after allogeneic stem cell transplantation

PURPOSE OF REVIEW

Relapse has become the leading cause of death following allogeneic hematopoietic stem cell transplantation (HSCT). Despite improved understanding of the biology that underlies the graft-versus-leukemia/tumor effect the relapse rate did not decrease over the past 20 years. In general, prognosis is poor for patients who relapsed to an allograft since effective treatment options are limited. Here, we review the available and upcoming treatment approaches for relapse.

RECENT FINDINGS

Treatment of relapse after allogeneic HSCT has been rarely investigated systematically and results differ substantially from diseases. Withdrawal of immunosuppressive medication, donor lymphocyte infusions with or without chemotherapy and/or second allogeneic HSCT are the most used options. New specific cellular approaches such as disease-specific T-cells, alloreactive natural killer cells or vaccination strategies are under investigation. Novel agents such as tyrosine-kinase inhibitors, hypomethylating agents, monoclonal antibodies, immunomodulating drugs, or proteasome-inhibitors either alone or in combination with adoptive immunotherapy are upcoming promising options, but valid data are lacking so far.

SUMMARY

With some exceptions (chronic myeloid leukemia), treatment options for patients who relapse are limited. The results are poor and the majority of patients ultimately die of their disease. More effort and research is needed to prevent and treat relapse after allogeneic HSCT.

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.

Outcome of 93 patients with relapse or progression following allogeneic hematopoietic cell transplantation

Relapse/progression after allogeneic hematopoietic cell transplantation (allo-HCT) remains the major cause of treatment failure. In this study, the subsequent clinical outcome was overviewed in 292 patients with leukemia/myelodysplastic syndrome who received allo-HCT. Among them, 93 (32%) showed relapse/progression. Cohort 1 was chosen to receive no interventions with curative intent (n = 25). Cohort 2 received reinduction chemotherapy and/or donor lymphocyte infusion (n = 48), and Cohort 3 underwent a second allo-HCT (n = 20). Sixty-three patients received reinduction chemotherapy, and 27 (43%) achieved subsequent complete remission (CR). The incidence of nonrelapse mortality (NRM) was similar among the three cohorts (4, 15, and 5%). The 1-year overall survival (OS) after relapse was significantly better in patients with a second HCT (58%) than in others (14%, Cohorts 1 and 2; P <.001). However, the 2-year OS did not differ between the two groups, which suggests that it is difficult to maintain CR after the second HCT. Multivariate analysis showed that reinduction chemotherapy, CR after intervention, second HCT, and longer time to post-transplant relapse were associated with improved survival. In conclusion, for patients with relapse after allo-HCT, successful reinduction chemotherapy and a second HCT may be effective for prolonging survival without excessive NRM. However, effective measures to prevent disease progression after a second HCT clearly need to be developed.

Management of relapse after allo-SCT for AML and the role of second transplantation

Relapse after allo-SCT for AML carries very poor prognosis. Second allo-SCT, although curative, is not an appropriate treatment option for a large number of relapsing patients (only 2-20% patients receive a second allo-SCT), and efforts to increase the number of patients who may benefit from a second allo-SCT are ongoing. In addition, understanding the varied biological processes that are operative in disease relapse has encouraged the development of novel therapies, and could be beneficial to patients who are currently managed conservatively with supportive care for relapsed disease. Incorporating novel combinations of drugs with immunomodulation, although theoretically attractive, should be tested in the setting of clinical trials. In this review, we discuss the currently available approaches for relapsed AML after allo-SCT.

ASH evidence-based guidelines: is there a role for second allogeneic transplant after relapse?

A 35-year-old male with a FLT3(+) AML underwent allogeneic peripheral blood stem cell transplant using a myeloablative non-total body irradiation (TBI) conditioning regimen from his HLA-matched sibling donor. Following transplantation, he developed grade II acute graft-versus-host disease (GVHD) that resolved with increasing immunosuppression. The medications were subsequently discontinued, and he did not develop any evidence of chronic GVHD. Eighteen months after transplant, while off all immunosuppression, he developed fatigue and a blood count showed circulating blasts consistent with relapse of his disease. Among the various therapeutic questions is whether there is a role for a second allogeneic transplant to treat his disease and if so, at what time, with what conditioning, and with which type of donor.

Outcome of second allogeneic transplants using reduced-intensity conditioning following relapse of haematological malignancy after an initial allogeneic transplant

Disease relapse following an allogeneic transplant remains a major cause of treatment failure, often with a poor outcome. Second allogeneic transplant procedures have been associated with high TRM, especially with myeloablative conditioning. We hypothesized that the use of reduced-intensity conditioning (RIC) would decrease the TRM. We performed a retrospective national multicentre analysis of 71 patients receiving a second allogeneic transplant using RIC after disease relapse following an initial allogeneic transplant. The majority of patients had leukaemia/myelodysplasia (MDS) (N=57), nine had lymphoproliferative disorders, two had myeloma and three had myeloproliferative diseases. A total of 25% of patients had unrelated donors. The median follow-up was 906 days from the second allograft. The predicted overall survival (OS) and TRM at 2 years were 28 and 27%, respectively. TRM was significantly lower in those who relapsed late (>11 months) following the first transplant (2 years: 17 vs 38% in early relapses; P=0.03). Two factors were significantly associated with a better survival: late relapse (P=0.014) and chronic GVHD following the second transplant (P=0.014). These data support our hypothesis that the second RIC allograft results in a lower TRM than using MA. A proportion of patients achieved a sustained remission even when relapsing after a previous MA transplant.

Outcomes of patients with AML and MDS who relapse or progress after reduced intensity allogeneic hematopoietic cell transplantation

We describe treatment, outcomes and prognostic factors for patients who relapse following transplantation with a reduced intensity conditioning regimen. Seventy consecutive patients with high-risk myeloid malignancies underwent transplant and 25 (36%) relapsed, a median of 120 days later. The median percentage of bone marrow blasts at relapse was 24, the median donor chimerism was 73% and new karyotypic abnormalities occurred in 8 out of 20 (40%) evaluable patients. Twenty-one patients (84%) received aggressive treatment for relapse, including chemotherapy (60%), second hematopoietic cell transplantation (HCT; 52%) and/or donor lymphocyte infusion (DLI; 12%). Thirteen achieved a complete response (CR) and four remain in CR. Median overall survival (OS) after relapse was 6 months (95% confidence interval=2.7-9.9 months), and actuarial 1 year OS was 24%. Most deaths were due to disease progression (17/20, 85%). We did not observe an advantage for cellular therapy (DLI or second transplant) compared to chemotherapy. Salvage therapy for relapse after reduced intensity HCT is feasible, associated with low treatment-related mortality, and may result in prolonged survival in select patients. Studies exploring the optimal treatment for relapse following reduced intensity HCT are warranted.

Prospective trial of high-dose chemotherapy followed by infusions of peripheral blood stem cells and dose-escalated donor lymphocytes for relapsed leukemia after allogeneic stem cell transplantation

To determine whether induction of graft-versus-host disease (GVHD) improves the outcome of acute relapsed leukemia after stem cell transplantation (SCT), we used high-dose cytarabine (ara-C) followed by infusions of donor-derived buffy coats containing peripheral blood stem cells to treat 12 patients with relapsed leukemia. Donor lymphocyte infusion (DLI) was repeated at least twice over a 5-week interval for patients in whom grade II to IV acute GVHD did not develop after the first DLI. Grade II to IV acute GVHD developed in 4 (33%) of the patients. Chronic GVHD developed in 3 patients, 2 of whom had not experienced acute GVHD. Four (67%) of the 6 patients who developed grade II to IV acute and/or chronic GVHD after DLI responded, but none of the other 6 patients responded. Four (33%) of the patients (2 with acute myelogenous leukemia [AML] and 2 with acute lymphoblastic leukemia [ALL]) achieved complete remission lasting longer than 4 months after the first DLI, but 3 of them had relapses in bone sites. Of these 4 patients, 1 patient with AML and 2 with ALL were alive 8 to 27 months after DLI. These findings indicate that high-dose ara-C combined with megadose DLI may produce durable remission of acute leukemia that has relapsed after SCT when GVHD is induced. The low induction rate of GVHD and extramedullary relapse after remission is achieved with DLI are problems yet to be solved.

Disease burden may identify patients more likely to benefit from second allogeneic hematopoietic stem cell transplantation to treat relapsed acute myelogenous leukemia

The major cause of failure after allogeneic hematopoietic stem cell transplantation (HSCT) for acute myelogenous leukemia (AML) is disease relapse or progression. We analyzed the outcome of second HSCT for treatment of patients with relapsed, refractory AML/myelodysplastic syndrome (MDS) at our institution. A total of 72 patients were eligible for this analysis. In all, 25 (35%) patients received salvage chemotherapy prior to the second transplant procedure and only two (3%) patients were in complete remission at the time of the second transplant. A total of 20 patients (28%) had low leukemia burden as measured by the absence of peripheral blood blasts and <or=5% blasts in the bone marrow at the time of the second transplant. Although, the overall median survival after the second transplant was 6 months, a subset of patients who had low leukemia burden at the time of the second transplant had a 5-year survival of 25 vs 12% in those with a high leukemia burden. Thus, a second transplant may offer the possibility of long-term disease control in a subset of patients who have a 'low bulk' disease at the time of transplantation.

Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Rescued with a Second Allogeneic Stem Cell Transplantation from a Haploidentical Mother after Relapse following Cord Blood Transplantation

A 32-year-old female patient who had Philadelphia chromosome-positive acute lymphoblastic leukemia underwent cord blood transplantation while in her second remission. However, she had a hematological and central nervous system relapse 3 months later. After reinduction with imatinib mesylate, unmanipulated peripheral blood stem cell transplantation was performed from the patient's haploidentical mother with a reduced-intensity conditioning regimen. Rabbit antithymocyte globulin, tacrolimus, and methylprednisolone were used for prophylaxis of graft-versus-host disease. Engraftment of neutrophils was observed on day 12, and complete donor chimerism was obtained by day 24. The posttransplantation course was uneventful. Although the patient had a relapse 10 months later, this case demonstrated that transplantation from a haploidentical donor is clearly a feasible alternative for patients who desperately need rescue transplantation.

Second allografts for relapsed hematologic malignancies: feasibility of using a different donor

A second allogeneic hematopoietic stem cell transplant (HSCT) for relapsed hematologic malignancies is an option in select patients after an initial allograft has failed. If the original donor is not available, a different donor may have to be considered. We report our experience of performing a second allogeneic HSCT using a different donor in patients with relapsed leukemia and lymphoma. In a 5-year period, six patients underwent a second allograft with myeloablative conditioning using a different donor. Four of these were retransplanted using a matched-unrelated donor. Four of the patients (67%) remain progression-free at a median follow-up of 32 months (range 3-72). There were no cases of transplant-related mortality. We conclude that a second allogeneic HSCT using a different donor is a viable option for selected patients relapsing after an allograft if the original donor is not available.

Allogeneic bone marrow transplantation in children with myelodysplastic syndrome or juvenile myelomonocytic leukemia: the Seattle experience

The purpose of this study was to evaluate the role of allogeneic bone marrow transplantation (BMT) in children with myelodysplastic syndrome (MDS). In total, 94 consecutive pediatric patients with MDS received an allogeneic BMT from 1976 to 2001 for refractory anemia (RA) (n=25), RA with ringed sideroblasts (RARS) (n=2), RA with excess blasts (RAEB) (n=20), RAEB in transformation (RAEB-T) (n=14), juvenile myelomonocytic leukemia (JMML) (n=32) or chronic myelomonocytic leukemia (CMML) (n=1). The estimated 3-year probabilities of survival, event-free survival (EFS), nonrelapse mortality and relapse were 50, 41, 28 and 29%, respectively. Patients with RA/RARS had an estimated 3-year survival of 74% compared to 68% in those with RAEB and 33% in patients with JMML/CMML. In multivariable analysis, patients with RAEB-T or JMML were 3.9 and 3.7 times more likely to die compared to those with RA/RARS and RAEB (P=0.005 and 0.004, respectively). Patients with RAEB-T were 5.5 times more likely to relapse (P=0.01). The median follow-up among the 43 surviving patients is 10 years (range 1-25). We conclude that allogeneic BMT for children with MDS is well tolerated and can be curative.

Second transplant for acute and chronic leukemia relapsing after first HLA-identical sibling transplant

Treatment options for persons with leukemia relapsing after allogeneic transplantation are limited. We analyzed the outcome of 279 patients with acute and chronic leukemia, who relapsed after HLA-identical sibling transplantation and received a second allogeneic transplant. The influence of potential risk factors on treatment-related mortality (TRM), relapse, treatment failure (relapse or death) and overall survival after second transplantation were assessed using proportional-hazards regression. The cumulative incidences (95% confidence interval) of relapse and TRM at 5 years were 42 (36-48)% and 30 (24-36)%, respectively. The 5-year probabilities of both overall and leukemia-free survival were 28 (23-34)%. In multivariate analyses, risks of treatment failure and mortality were lower in younger patients (< or =20 years) and patients who relapsed after 6 months from first transplantation. Risks of relapse were lower in patients who relapsed after 6 months from first transplantation and in complete remission prior to second transplantation. Risks of relapse were higher after reduced-intensity conditioning regimens. Any potential advantage of using a different matched related donor for a second transplantation is not supported by these data. Although age, disease status and conditioning regimen are important, duration of remission after first transplantation appear to be the most important determinant of outcome.

Second allogeneic hematopoietic stem cell transplantation for juvenile myelomonocytic leukemia: case report and literature review

Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disease in young childhood. Hematopoietic stem cell transplantation (HSCT) is the only way to cure the disease, but relapse after HSCT remains a major cause of treatment failure. A 5-year-old girl with JMML, who had experienced a relapse after the first transplant, did not respond to donor lymphocyte infusion and withdrawal of immune-suppressing agents. She was successfully treated using a second transplant. Detailed reports from the English literature since 1988 relating to a total of 13 JMML patients undergoing a second transplant were reviewed. Seven of the 13 JMML patients (54%) were alive and disease-free, with a median follow-up of 53 months after the second transplant. Within the first 6 months following the initial transplant, 10 JMML patients suffered either autologous recovery (n = 6) or early relapse (n = 4). Seven of the 10 (70%) were alive, with a median survival period of 53 months after the second transplant. Six JMML patients underwent retransplantation within 6 months of the first transplant, with three of these (50%) alive at follow-ups of 24, 57, and 90 months after the second procedure. The authors conclude that a second transplant within 6 months may be worth considering for JMML patients who experience autologous recovery or earlier relapse after the first transplant.

Donor lymphocyte infusion to treat relapse after allogeneic bone marrow transplantation for myelodysplastic syndrome

Donor lymphocyte infusion has become established as a salvage therapy for patients with hematological disorders relapsing after allogeneic bone marrow transplantation (BMT). The role of donor lymphocyte infusion for patients with myelodysplastic syndrome (MDS) remains to be established. Between July 1993 and October 2001, 14 patients with MDS relapsing after allogeneic BMT received DLI as salvage therapy. At the time of BMT, one patient had RA, nine had RAEB, of whom three were in CR after induction-type chemotherapy, two had RAEB-T, one had CMML and one had AML. Donors were HLA-matched siblings (n=12), HLA-matched other relative (n=1) and unrelated (n=1). At the time of relapse, the median marrow blast count was 9%. The median CD3+ cell dose administered was 6.3 x 10(7)/kg. With a median follow-up of 49 months, six patients were alive, of whom two were in CR after DLI alone and remained disease-free, two were in CR after a second BMT and two had active disease. Eight patients died of disease progression. Although DLI alone seems to be effective in a small number of patients with MDS, other treatment strategies, including prior debulking chemotherapy, deserve investigation.

A pilot study of cytoreductive chemotherapy combined with infusion of additional peripheral blood stem cells reserved at time of harvest for transplantation in case of relapsed hematologic malignancies after allogeneic peripheral blood stem cell transplant

Reharvesting leukocytes from donors for a donor leukocyte infusion (DLI) is inconvenient and occasionally impossible in case of unrelated donors. It is well known that the effect of a growth factor-primed DLI is comparable to that of a nonprimed DLI. In total, 42 patients with hematologic malignancies and a high risk of relapse were allocated, on an intent-to-treat basis, a peripheral blood stem cell transplantation (PBSCT) from HLA-matched sibling donors, and then at the time of harvest, additional peripheral blood stem cells (PBSCs) were also reserved for a therapeutic primed DLI in case of relapse. In all, 12 patients who relapsed after allogeneic PBSCT were treated with mainly cytarabine-based chemotherapy followed by a cryopreserved PBSC infusion. The median dose of CD3+ and CD34+ cells for the primed DLIs was 1.43 x 10(8)/kg and 4.75 x 10(6)/kg, respectively. Six of the 12 relapsed patients exhibited a complete response after the primed DLI, plus their 1-year survival rate was 33%. The new development or progression of graft-versus-host disease after a primed DLI was observed in 50% of the patients. Overall, the survival at 1 year was 16.7%. Accordingly, the induction of a graft-versus-leukemia effect through a primed DLI, using additional PBSCs reserved at the original time of harvest, would appear to be feasible for patients with relapsed hematologic malignancies. Furthermore, this approach is also more convenient for donors.