High incidence of extramedullary relapse of AML after busulfan/cyclophosphamide conditioning and allogeneic stem cell transplantation

Acute Leukemia Relapse after Hematopoietic Stem Cell Transplantation: The Good, the Bad, and the Ugly of Isolated Extramedullary Relapse in a Latin American Population

Hematopoietic stem cell transplantation (HSCT) is an effective therapy for acute leukemia (AL). Relapse represents the main cause of mortality. Isolated extramedullary relapse (iEMR) is atypical and has been related to better outcomes. Here we describe the clinical characteristics and outcomes of AL relapse after HSCT in our study population and analyze the impacts of different types of relapse on survival outcomes. This retrospective, multicenter study included 124 patients age ≥15 years with AL who underwent HSCT between 2004 and 2019. At diagnosis, 66.1% of the patients had lymphocytic AL, 19.7% presented with high-risk features, and 18.5% had extramedullary disease (EMD). At HSCT, 83.1% of the patients were in complete remission (CR), and 44.8% had negative measurable residual disease (MRD). The vast majority of donors were related (96%), including 48.4% HLA-matched and 47.6% haploidentical. Myeloablative conditioning was provided to 80.6% of patients. The median overall survival (OS) was 15 months (95% confidence interval [CI] 9.9 to 20.1 months). Factors associated with improved OS were adolescent and young adult (AYA) patient (P = .035), first or second CR (P = .026), and chronic graft-versus-host disease (GVHD) (P < .001). Acute GVHD grade III-IV (P = .009) was associated with increased mortality. The median relapse-free survival was 13 months (95% CI, 7.17 to 18.8 months); early disease status (P = .017) and chronic GVHD (P < .001) had protective roles. Sixty-eight patients (55%) relapsed after HSCT, with a median time to relapse of 6 months (95% CI, 3.6 to 8.4 months). iEMR was reported in 16 patients (23.5%). The most commonly involved extramedullary sites were the central nervous system and skin. Compared to patients with bone marrow relapse, all patients with iEMR had a diagnosis of acute lymphoid leukemia (P = .008), and 93.8% belonged to the AYA group; regarding pre-HSCT characteristics, iEMR patients had higher rates of negative MRD (P = .06) and a history of EMD (P = .009). Seventy-seven percent of relapsed patients received additional treatment with curative intent. The median OS after relapse (OSr) was 4 months (95% CI, 2.6 to 5.4 months). Factors related to increased OSr included lymphoid phenotype (P = .03), iEMR (P = .0042), late relapse (≥6 months) (P = .014), receipt of systemic therapy including second HSCT (P < .001), and response to therapy (P < .001). Rates of relapse and iEMR were higher than those previously reported in other studies. Advanced disease, reduced-intensity conditioning, and a diminished graft-versus-leukemia effect were factors influencing these findings. At relapse, presenting with iEMR after 6 months and receiving intensive therapy with adequate response were associated with better outcomes. Our results strongly suggest that a personalized approach to treating patients with HSCT is needed to counterbalance specific adverse factors and can positively impact clinical outcomes.

A Case of Central Nervous System Post-Transplant Lymphoproliferative Disorder Following Haploidentical Stem Cell Transplantation in a Patient With Acute Lymphoblastic Leukemia

We present a differential diagnosis of an intracranial lesion following haploidentical stem cell transplantation (haplo-SCT) in a female patient with acute lymphoblastic leukemia (ALL). This patient received an anti-CD19-chimeric antigen receptor (CAR) T-cell therapy for refractory B-cell ALL and obtained minimal residual disease (MRD)-positive (0.03%) complete remission (CR). Then the patient received a bridging therapy of haplo-SCT. After bridging therapy, the patient maintained MRD-negative and full donor chimerism in bone marrow (BM) and was negative for Epstein–Barr virus (EBV)-DNA copy in peripheral blood. At 91 days after haplo-SCT, the patient presented with dizziness and fatigue and magnetic resonance imaging (MRI) demonstrated an intracranial lesion. The diagnosis of isolated extramedullary relapse (IEMR) was temporarily considered. Then next-generation sequencing (NGS) identified positive EBV-DNA in the cerebrospinal fluid, although EBV-DNA in the peripheral blood was negative. Furthermore, the positive EBV-DNA by NGS and complete donor chimerism in the brain tissue confirmed the diagnosis of central nervous system post-transplant lymphoproliferative disorder (CNS-PTLD). However, the EBV-encoded small RNAs (EBERs) in situ hybridization was sparsely positive. The patient was subsequently treated with anti-CD22-CAR T cells in combination with Zanubrutinib, but the disease progressed quickly and died. Donor chimerism examination of focal biopsy provides important evidence for diagnosing PTLD. Furthermore, NGS detection of EBV-DNA in local lesions is more valuable for diagnosing PTLD than detection of EBV-DNA in the peripheral blood.

Trial registration: The patient was enrolled in a clinical trial of ChiCTR1800019622 and ChiCTR1800019298.

Different Kinetics and Risk Factors for Isolated Extramedullary Relapse after Allogeneic Hematopoietic Stem Cell Transplantation in Children with Acute Leukemia

Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the most frequent cause of post-transplantation mortality. Isolated extramedullary (EM) relapse (iEMR) after HSCT is relatively rare and not well characterized, particularly in pediatric patients. We retrospectively analyzed 1527 consecutive pediatric patients with acute leukemia after allo-HSCT to study the incidence, risk factors, and outcome of iEMR compared with systemic relapse. The 5-year cumulative incidence of systemic relapse (either bone marrow [BM] only or BM combined with EMR) was 24.8%, and that of iEMR was 5.5%. The onset of relapse after allo-HSCT was significantly longer in EM sites than in BM sites (7.19 and 5.58 months, respectively; P = .013). Complete response (CR) 2+/active disease at transplantation (hazard ratio [HR], 3.1; P < .001) and prior EM disease (HR, 2.3; P = .007) were independent risk factors for iEMR. Chronic graft-versus-host disease reduced the risk of systemic relapse (HR, 0.5; P = .043) but did not protect against iEMR. The prognosis of patients who developed iEMR remained poor but was slightly better than that of patients who developed systemic relapse (3-year overall survival, 16.5% versus 15.3%; P = .089). Patients experiencing their first systemic relapse continued to have further systemic relapse, but only a minority progressed to iEMR, whereas those experiencing their iEMR at first relapse developed further systemic relapse and iEMR at approximately similar frequencies. A second iEMR was more common after a first iEMR than after a first systemic relapse (58.8% versus 13.0%; P = .001) and was associated with poor outcome. iEMR has a poor prognosis, particularly after a second relapse, and effective strategies are needed to improve outcomes.

Myeloid sarcoma, chloroma, or extramedullary acute myeloid leukemia tumor: A tale of misnomers, controversy and the unresolved

The World Health Organization classification and definition of "myeloid sarcoma" is imprecise and misleading. A more accurate term is "extramedullary acute myeloid leukemia tumor (eAML)." The pathogenesis of eAML has been associated with aberrancy of cellular adhesion molecules, chemokine receptors/ligands and RAS-MAPK/ERK signaling. eAML can present with or without synchronous or metachronous intramedullary acute myeloid leukemia (AML) so a bone marrow evaluation is always recommended. Accurate diagnosis of eAML requires tissue biopsy. eAML confined to one or a few sites is frequently treated with local therapy such as radiotherapy. About 75-90% of patients with isolated eAML will develop metachronous intramedullary AML with a median latency period ranging from 4 to 12 months; thus, patients with isolated eAML may also be treated with systemic anti-leukemia therapy. eAML does not appear to have an independent prognostic impact; selection of post-remission therapy including allogeneic hematopoietic cell transplant (alloHCT) is typically guided by intramedullary disease risk. Management of isolated eAML should be individualized based on patient characteristics as well as eAML location and cytogenetic/molecular features. The role of PET/CT in eAML is also currently being elucidated. Improving outcomes of patients with eAML requires further knowledge of its etiology and mechanism(s) as well as therapeutic approaches beyond conventional chemotherapy, ideally in the context of controlled trials.

Extra-medullary recurrence of myeloid leukemia as myeloid sarcoma after allogeneic stem cell transplantation: impact of conditioning intensity

Myeloid sarcoma (MS) as a solid extra-medullary (EM) manifestation of acute myeloid leukemia (AML), myeloproliferative or myelodysplastic syndromes is a rare presentation of relapse after allogeneic hematopoietic stem cell transplantation (HSCT). The databases of the Departments of Hematology and Oncology of the University Hospitals of Jena and Rostock were screened for patients aged 18 years or older for onset of MS after HSCT for myeloid malignancies between 2002 and 2019. Nineteen patients with MS were identified, the majority of whom had received reduced-intensity conditioning (RIC). The median onset of MS was 425 days after HSCT and the median overall survival since MS was 234 days. Although MS is associated with a poor prognosis, three patients survived more than two years and one more than 11 years after MS onset. These results indicate that RIC protocols may be associated with a higher risk of EM relapse. Since EM relapse occurred in the presence of Graft-versus-host-disease, these observations also demonstrate the limitations of graft-versus-tumor effects after HSCT. In conclusion, occurrence of MS after HSCT is associated with a poor prognosis, as multimodal curative concepts including intensive chemotherapy and another HSCT are often not viable.

Lysyl oxidase expression is associated with inferior outcome and Extramedullary disease of acute myeloid leukemia

BACKGROUND

Lysyl oxidase (LOX) has been described as necessary for premetastatic niche formation in epithelium-derived malignancies and its expression level therefore correlates with risk of metastatic disease and overall survival. However, its role in acute myeloid leukemia (AML) has not been sufficiently analyzed.

METHODS

We investigated LOX plasma expression in 683 AML patients (age 17-60 years) treated within the prospective AML2003 trial (NCT00180102). The optimal cut-off LOX value was determined using a minimal-p-value method dichotomizing patients into a LOX-high group (> 109 ng/mL, n = 272, 40%) and a LOX-low group (≤ 109 ng/mL, n = 411, 60%).

RESULTS

Higher LOX expression was associated with lower peripheral white blood cells, lower serum LDH, and a lower frequency of FLT3-ITD and NPM1 mutations at diagnosis. Higher LOX expression was found significantly more frequently in patients with secondary AML and therapy-related AML, in patients with French-American-British M5 subtypes, and in patients with adverse-risk cytogenetics. Comparing patients in the LOX-high group and the LOX-low group revealed a 3-year overall survival (OS) of 47 and 53% (p = 0.022) and 3-year event-free survival (EFS) of 27 and 35% (p = 0.005), respectively. In the LOX-high group significantly more patients had extramedullary AML compared to the LOX-low group (p = 0.037). Combining extramedullary AML and LOX as interacting factors in a multivariate analysis resulted in an independent impact on survival for the LOX-high-extramedullary interaction for OS (HR = 2.25, p = 0.025) and EFS (HR = 2.48, p = 0.008). Furthermore, in patients with extramedullary disease (n = 59) the LOX level predicted survival. Patients within the LOX-low group had an OS of 43% and EFS of 36% as compared to the LOX-high group with an OS of 13% and EFS of 6% (p = 0.002 and p = 0.008, respectively).

CONCLUSION

We hypothesize LOX expression to be a new potential biomarker to predict outcome in AML, specifically in AML subgroups such as the prognostic heterogeneous group of AML patients with extramedullary disease.

TRIAL REGISTRATION

This retrospective study was performed with patient samples registered within the prospective AML2003 trial (NCT00180102). Patients were enrolled between December 2003 and November 2009.

Complete response of myeloid sarcoma with cardiac involvement to radiotherapy

We present a rare case of intracardiac myeloid sarcoma (MS) of acute myeloid leukemia (AML) and who responds completely well to low-dose radiotherapy. This 19-year-old young man initially presented with AML and received standard chemotherapy followed by allogeneic hematopoietic stem cell transplantation (HSCT). However, he developed intracardiac isolated MS relapse with the presentation of exertional dyspnea and superior vena cava (SVC) syndrome 3 years later. He then received radiotherapy with 24 Gy at a 12 daily fractions using forward "field in field" intensity modulated radiotherapy technique. He dramatically had improved clinical symptoms, and complete remission was achieved one month after completing radiotherapy. Our result is in line with anecdotal case reports showed that radiotherapy with 15 Gy in 10 fractions or with 24 Gy in 12 fractions resulted in good response and less toxicity of 2 cases of MS with cardiac involvement. These results indicate that a modest radiotherapy dose, 24 Gy, achieves good local control of MS with cardiac involvement.

Usefulness and pitfalls of F-18-FDG PET/CT for diagnosing extramedullary acute leukemia

PURPOSE

It is very important to identify whether there is extramedullary involvement in acute leukemia (AL), especially in those with recurrent disease. This retrospective study aimed to assess the role of (18)F-FDG PET/CT for diagnosing extramedullary AL.

MATERIALS AND METHODS

PET/CT examinations were performed in 9 patients with newly diagnosed AL, and 70 patients suspected to have recurrent AL. All the patients were diagnosed with AL by bone marrow biopsy. The diagnosis of extramedullary lesions was established according to the combination of pathology, physical examination, and imaging techniques including magnetic resonance imaging (MRI) and PET/CT, and/or cerebrospinal fluid (CSF) cytologic testing, and clinical follow-up.

RESULTS

Of the 79 patients, including 34 acute lymphocytic leukemia (ALL) and 45 acute myeloid leukemia (AML) cases, 30 patients were diagnosed with extramedullary AL. (18)F-FDG PET/CT demonstrated (18)F-FDG positive lesions in the extramedullary regions in 42 patients. Among them, 28 patients were diagnosed to have extramedullary AL and the other 14 were diagnosed with non-hematological malignancies (false positive disease). The sensitivity, specificity, and accuracy of (18)F-FDG PET/CT in diagnosing extramedullary involvement of AL were 93.3% (28/30), 71.4% (35/49), and 79.7%, respectively. The (18)F-FDG uptake of lesions was not significantly different between extramedullary AL and false positive cases (SUVmax: 6.66 ± 2.65 vs. 5.85 ± 1.88, t=1.275, P=0.206). The FDG uptake of extramedullary AL between ALL and AML were also not significantly different (SUVmax: 7.01 ± 2.82 vs. 6.10 ± 2.29, t=1.332, P=0.188). The predominant locations of extramedullary AL were the spleen, soft tissue, lymph nodes, central nerve system, liver, testis, and kidney. A total of 48.2% (27/56) of extramedullary AL lesions presented as diffuse FDG uptake compared with 6.25% (1/16) in the false positive lesions (χ(2)=9.221, P=0.002).

CONCLUSION

(18)F-FDG PET/CT is a sensitive, but not specific imaging modality for diagnosing extramedullary AL. Diffuse (18)F-FDG uptake in extramedullary lesions may indicate leukemia involvement.

Extramedullary relapse of acute leukemia after allogeneic hematopoietic stem cell transplantation: different characteristics between acute myelogenous leukemia and acute lymphoblastic leukemia

Extramedullary relapse (EMR) of acute leukemia (AL) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a contributor to post-transplantation mortality and remains poorly understood, especially the different characteristics of EMR in patients with acute myelogenous leukemia (AML) and those with acute lymphoblastic leukemia (ALL). To investigate the incidence, risk factors, and clinical outcomes of EMR for AML and ALL, we performed a retrospective analysis of 362 patients with AL who underwent allo-HSCT at the First affiliated Hospital of Soochow University between January 2001 and March 2012. Compared with patients with AML, those with ALL had a higher incidence of EMR (12.9% versus 4.6%; P = .009). The most common site of EMR was the central nervous system, especially in the ALL group. Multivariate analyses identified the leading risk factors for EMR in the patients with AML as advanced disease status at HSCT, hyperleukocytosis at diagnosis, history of extramedullary leukemia before HSCT, and a total body irradiation-based conditioning regimen, and the top risk factors for EMR in the patients with ALL as hyperleukocytosis at diagnosis, adverse cytogenetics, and transfusion of peripheral blood stem cells. The prognosis for EMR of AL is poor, and treatment options are very limited; however, the estimated 3-year overall survival (OS) was significantly lower in patients with AML compared with those with ALL (0 versus 18.5%; P = .000). The characteristics of post-allo-HSCT EMR differed between the patients with AML and those with ALL, possibly suggesting different pathogenetic mechanisms for EMR of AML and EMR of ALL after allo-HSCT; further investigation is needed.

Imaging of Abdominal Complications Associated with Hematopoietic Stem Cell Transplantation

Complications associated with hematopoietic stem cell transplantation are common and frequently involve the gastrointestinal tract and other abdominal organs. Imaging is often used to help to confirm or exclude a suspected complication and to facilitate management. In this article, we review the imaging findings of abdominal complications related to hematopoietic stem cell transplantation.

Imaging findings in recurrent extramedullary leukaemias

Acute leukaemias are relatively common malignancies. Treatment has advanced significantly in the recent past and there has been improved patient survival. This improved initial response is leading to an increasing number of cases of relapse. Extramedullary relapse occurs in a wide variety of locations with varying presentations, imaging findings and differentials. The pathophysiology and clinical course of recurrent extramedullary myeloid and lymphocytic leukaemias are reviewed in this article. The wide variety of imaging findings associated with many important sites of recurrence and the associated differential diagnosis are discussed and illustrated.

Clinical characteristics and outcome of isolated extramedullary relapse in acute leukemia after allogeneic stem cell transplantation: a single-center analysis

Isolated extramedullary relapse (EMR) of acute leukemia (AL) is a rare occurrence. However, it appears to be more common after allogeneic stem cell transplantation (allo-SCT). To characterize what has been observed in isolated EMR, we investigated 287 consecutive AL patients (144 acute myeloid leukemia; 138 acute lymphocytic leukemia; 5 acute mixed-lineage leukemia) who underwent allo-SCT. Twelve cases experienced relapse at extramedullary sites without concomitant involvement of the bone marrow (BM). The onset to relapse after allo-SCT was longer in extramedullary sites than in the BM (median, 10 months versus 5.5 months). EMR sites varied widely and included the central nervous system, skin, bone, pelvis and breasts. Univariate analysis demonstrated that cytogenetic abnormalities were correlated significantly with the onset of isolated EMR (P=0.001). The prognosis for patients who develop EMR remained poor but was relatively better than that after BM relapse (overall survival, 10 versus 18 months). Compared with local or single therapy, patients treated with systemic treatment in combination with local treatment could yield a favorable prognosis. In conclusion, we observed a significant number of isolated cases of EMR in AL patients after allo-SCT, cytogenetic abnormalities were correlated significantly with the onset of isolated EMR. We found that intensive approaches combining local and systemic therapy could produce favorable responses which may cure a proportion of these patients.

Extramedullary relapse of acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation: incidence, risk factors and outcomes

Extramedullary relapse after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia is a contributor to post-transplant mortality but risk factors for, and outcomes of, this condition are not well characterized. We analyzed 257 consecutive patients undergoing allogeneic stem cell transplantation for acute myeloid leukemia at our institution to characterize extramedullary relapse, identify predictive variables and assess outcomes. The 5-year cumulative incidence of isolated extramedullary or bone marrow relapse was 9% and 29%, respectively. Extramedullary relapse occurred later than marrow relapse and most frequently involved skin and soft tissue. Factors predictive of extramedullary relapse after transplantation included previous extramedullary disease, French-American-British classification M4/M5 leukemia, high risk cytogenetics, and advanced disease status at the time of transplantation. Children were more likely than adults to develop extramedullary relapse, a finding probably explained by an overrepresentation of extramedullary disease prior to transplantation and M4/M5 leukemia in children. Acute graft-versus-host disease was not protective against relapse. Unlike medullary relapse, chronic graft-versus-host disease was not protective against extramedullary relapse. The survival rate after extramedullary relapse was 30% at 1 year and 12% at 2 years. Extramedullary relapse is a significant contributor to mortality after allogeneic transplantation for acute myeloid leukemia and appears to be resistant to the immunotherapeutic effect of allogeneic grafting. Effective strategies for patients with extramedullary relapse are needed to improve outcomes after transplantation.

Extramedullary relapse of acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation: incidence, risk factors and outcomes

Extramedullary relapse after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia is a contributor to post-transplant mortality but risk factors for, and outcomes of, this condition are not well characterized. We analyzed 257 consecutive patients undergoing allogeneic stem cell transplantation for acute myeloid leukemia at our institution to characterize extramedullary relapse, identify predictive variables and assess outcomes. The 5-year cumulative incidence of isolated extramedullary or bone marrow relapse was 9% and 29%, respectively. Extramedullary relapse occurred later than marrow relapse and most frequently involved skin and soft tissue. Factors predictive of extramedullary relapse after transplantation included previous extramedullary disease, French-American-British classification M4/M5 leukemia, high risk cytogenetics, and advanced disease status at the time of transplantation. Children were more likely than adults to develop extramedullary relapse, a finding probably explained by an overrepresentation of extramedullary disease prior to transplantation and M4/M5 leukemia in children. Acute graft-versus-host disease was not protective against relapse. Unlike medullary relapse, chronic graft-versus-host disease was not protective against extramedullary relapse. The survival rate after extramedullary relapse was 30% at 1 year and 12% at 2 years. Extramedullary relapse is a significant contributor to mortality after allogeneic transplantation for acute myeloid leukemia and appears to be resistant to the immunotherapeutic effect of allogeneic grafting. Effective strategies for patients with extramedullary relapse are needed to improve outcomes after transplantation.

Allogeneic hematopoietic stem cell transplantation for adult AML patients with granulocytic sarcoma

We recently reported that adult acute myeloid leukemia (AML) patients with granulocytic sarcoma (GS) possessed unique clinical features and poor prognosis. However, the optimal therapeutic strategy for this entity has not been established. Therefore, the aim of this study was to assess the efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for the management of AML with GS. We retrospectively analyzed 503 consecutive adult AML patients (median age, 44 years; range, 15-73 years) who received allo-HSCT. A total of 44 patients (8.7%) had GS before transplantation. Patients with GS achieved comparable survival to those without GS (5-year overall survival (OS), 47% vs 44%, respectively, P=0.621). In patients with GS, excellent outcomes were seen in those that underwent allo-HSCT while in complete remission, whereas nine out of ten patients with GS at the time of transplant experienced a relapse within 6 months after allo-HSCT. Local irradiation for GS prior to allo-HSCT and acute and chronic graft-versus-host disease did not affect survival significantly. Multivariate analysis identified age, disease status and the use of myeloablative conditioning as independent prognostic factors for OS. These data suggest that better control of GS prior to allo-HSCT is crucial to improve the outcome of transplantation for those with GS.

Extramedullary relapse of acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation: an easily overlooked but significant pattern of relapse

Acute myeloid leukemia may manifest as myeloid sarcoma in a variety of extramedullary (EM) tissues at diagnosis or at relapse. Although EM relapse after allogeneic hematopoietic stem cell transplantation (alloSCT) has been considered to be rare, recent studies have suggested that it occurs in 5% to 12% of patients who receive alloSCT, accounting for 7% to 46% of total relapses. The incidence of EM relapse after immunomodulation (eg, donor lymphocyte infusion) or a second SCT is even higher. Moreover, patients with EM relapse are more likely to have had preceding acute graft-versus-host disease or chronic graft-versus-host disease relative to those with bone marrow relapse. Collectively, these observations suggest that the preferential occurrence of the graft-versus-leukemia effect underlies the pathogenesis of EM relapse. Establishing an early diagnosis of EM relapse has been challenging because of the immense diversity in the relapse sites; however, recent studies have suggested the usefulness of (18)F-fluorodeoxyglucose positron emission tomography scans in the detection of EM relapse. As a treatment for EM relapse, a combination of local and systemic therapy should be considered, because local therapy alone often results in subsequent systemic relapse. The prognosis for patients who develop EM relapse after SCT remains poor but is slightly better than that after bone marrow relapse. In addition to an early diagnosis with new modalities, clinical studies using new agents that may offer systemic activity while preserving the graft-versus-leukemia effect are warranted as part of an effort to improve the clinical outcome.

Extramedullary relapse of acute myelogenous leukemia after allogeneic hematopoietic stem cell transplantation: better prognosis than systemic relapse

Allogeneic hematopoietic cell transplantation (HSCT) is considered a curative treatment for acute myelogenous leukemia (AML). Extramedullary relapse after HSCT for AML is a rare event and is less well defined than systemic, hematologic relapse. We retrospectively studied all patients with AML (n = 436) who underwent HSCT at the University of Minnesota between 1996 and 2008 who developed either a bone marrow (BM) or extramedullary (EM) relapse, and examined the incidence and risk factors for BM and EM relapse. Of 128 patients who relapsed post-HSCT, 25 had relapse in EM sites, either isolated (n = 13) or with concurrent BM relapse (n = 12). Relapse sites included bone (n = 1), central nervous system (n = 6), gastrointestinal (n = 4), lymphatic (n = 4), skin (n = 5), genitourinary (n = 1), pulmonary (n = 1), and soft tissue (n = 3). The time to relapse was longer in the EM sites (median, 328 days vs 168 days). Patients with EM relapse were more likely to have had preceding acute graft-versus-host disease (GVHD) (77% vs 49%; P = .03) or chronic GVHD (46% vs 15%; P = .02) compared with those with BM relapse. The 6-month survival postrelapse was significantly better in patients with isolated EM relapse (69%) compared with those with combined EM and BM relapse (8%) or those with BM relapse alone (27%) (P < .01). Compared with local therapy alone, systemic therapy yielded better 6-month survival in patients with EM relapse. This study suggests differing pathogenesis of BM relapse versus EM relapse of AML after allogeneic HSCT. GVHD and its accompanying graft-versus-leukemia effect may better protect BM sites, but patients with EM relapse have better responses to combined therapy and improved survival compared with those with BM relapse.

Blockade of interleukin-23 signaling results in targeted protection of the colon and allows for separation of graft-versus-host and graft-versus-leukemia responses

Allogeneic stem cell transplantation is the most potent form of effective adoptive immunotherapy. The graft-versus-leukemia (GVL) effect mediated by the allogeneic graft, however, is typically coexpressed with graft-versus-host disease (GVHD), which is the major complication of allogeneic stem cell transplantation. In this study, we used genetic and antibody-based strategies to examine the effect that blockade of interleukin 23 (IL-23) signaling had on GVH and GVL reactivity in murine transplantation recipients. These studies demonstrate that the selective protection of the colon that occurs as a consequence of inhibition of IL-23 signaling reduces GVHD without loss of the GVL effect. The separation of GVH and GVL reactivity was noted in both acute and chronic hematologic malignancy models, indicating that this approach was not restricted by the kinetic profile of the underlying leukemia. Furthermore, a potent GVL response could be mounted in the colon under conditions where tumor cells migrated to this site, indicating that this organ did not serve as a sanctuary site for subsequent systemic relapse in GVHD-protected animals. These studies demonstrate that blockade of IL-23 signaling is an effective strategy for separating GVH and GVL responses and identify IL-23 as a therapeutic target for the regulation of alloresponses in humans.

Isolated extramedullary relapse presenting as autologous lymphocyte response

Isolated EMR in the CNS is a relatively rare form of recurrent leukemia. We report here a case of a 38-year-old man with inv(16) acute myeloid leukemia (AML, M2) who suffered a central nervous system (CNS) relapse after allogeneic bone marrow transplantation (BMT) from a human leukocyte antigen (HLA)-matched sibling donor. After complete remission was achieved by chemotherapy, he received allogeneic BMT from his HLA-matched sister. His leukemia relapsed in the CNS 2.5 years after the allogeneic BMT. Lumbar puncture revealed 780/muL white blood cells with 67.3% leukemia cells and 32.7% mature lymphocytes. Fluorescent in situ hybridization (FISH) using a probe for the Y chromosome demonstrated that both leukemia cells and lymphocytes in the cerebrospinal fluid (CSF) were derived from the recipient, although the bone marrow cells were from the donor. No leukemia cells with inv(16) were detected by FISH in the bone marrow. This is the first report to clarify the chimerism of lymphocytes in the CSF of patients with isolated EMR in the CNS after allogeneic SCT, in which analysis revealed that autologous immunologic cells rather than donor lymphocytes responded to the recurrent isolated leukemic cells in CNS. This observation suggests that the CNS is a "sanctuary" site not only from chemotherapy but also from the graft-versus-leukemia effect. The present case contributes to our understanding of the possibility of immunological escape phenomenon of recurrent leukemia cells in extramedullary sites.

Gemtuzumab therapy for isolated extramedullary AML relapse following allogeneic stem-cell transplant

BACKGROUND

A 19-year-old male with primary refractory acute myeloid leukemia received salvage therapy with mitoxantrone and cytarabine combination. He received consolidation therapy 3 months later with a matched-unrelated-donor stem-cell transplant. The disease relapsed in the bone marrow (BM) 9 months after the initial stem-cell transplant, and was successfully treated by repeat transplant from the same donor. Ten months following repeat transplant, the patient presented with an increasing number of extramedullary sites of biopsy-proven disease relapse (i.e. cranial and peripheral nerves, tongue, abdominal wall and chest wall). Repeated biopsy of the BM and chimera study showed no morphologic evidence of leukemic infiltrate with 100% donor-cell population.

INVESTIGATIONS

Physical examination, complete blood count, BM biopsy, flow cytometry, cytogenetic analysis, chimera study, tongue biopsy, abdominal-wall biopsy, cytology and immunohistochemistry, CT scan of the chest, abdomen and pelvis, MRI of the brain, and cerebrospinal fluid analysis.

DIAGNOSIS

Isolated extramedullary relapse of acute myeloid leukemia after stem-cell transplant.

MANAGEMENT

Primary leukemia treatment with idarubicin, cytarabine, etoposide, dexamethasone, tioguanine on protocol and salvage therapy with mitoxantrone and cytarabine combination for primary refractory disease. A matched-unrelated-donor stem-cell transplant for consolidation and donor-lymphocyte infusions were performed, followed by repeat unrelated-donor transplant for leukemia relapse in the marrow, radiation therapy and gemtuzumab ozogamicin for multiple sites of extramedullary leukemia relapse.

Repeated relapses of acute myelogenous leukemia in the isolated extramedullary sites following allogeneic bone marrow transplantations

Isolated extramedullary (EM) relapses of acute myelogenous leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) have been reported to be rare, and are usually followed by bone marrow relapses. We report a 49-year-old man with AML with the unfavorable chromosome abnormality 7q-, who was treated by allo-HSCT. Fifteen months after allo-HSCT, the patient initially developed a relapse only in his inguinal lymph nodes, and then bone marrow relapse became evident one month after the EM relapse. Subsequently, the patient received chemotherapy and a second allo-HSCT from another donor, but he suffered another relapse in different EM sites including the skin and central nervous system with a persistently normal marrow. This case is characterized by repeated relapses in isolated EM sites after allo-HSCT and suggests that the anti-leukemic effects of chemotherapy and/or graft-versus-leukemia effects in the EM sites might not be so uniformly effective as that in the marrow. Accordingly, we should be aware that AML relapses can occur repeatedly only in isolated EM sites post allo-HSCT, resulting in treatment failure and a poor prognosis.

Extramedullary sites of leukemia relapse after transplant

Recurrent or residual leukemia found in extramedullary sites after intensive treatments adversely affects prognosis. To summarize the sites and outcomes when extramedullary relapses have been reported after stem cell transplants, and to elucidate when long survival has been achieved, 207 cases were analysed. Authors were contacted for follow-up information. The most commonly reported sites are soft tissue in acute leukemias and bone in CML. Extramedullary relapse occurred typically within 2 years in ALL, but later in one-third of myeloid leukemias. Most testicular relapses reported in AML followed non-TBI conditioning. Marrow relapse was not inevitable if aggressive treatment was begun early. Local therapy alone was generally inadequate. Intensive therapy has produced lengthy remissions in cases of acute leukemias involving various sites, whereas CML cases, particularly involving bone, were most resistant to treatment. Heightened awareness and aggressive treatment should improve the prospect for cure after extramedullary relapse.

Isolated extramedullary relapse after autologous bone marrow transplantation for acute myeloid leukemia: case report and review of the literature

Isolated extramedullary relapse (IEMR) is a pattern of acute myeloid leukemia (AML) relapse post-allogeneic bone marrow transplantation (alloBMT). Less is known about IEMR post-autologous BMT (autoBMT) and about factors associated with IEMR. We report a case of a woman with M4 AML who experienced IEMR post-autoBMT and review the related literature. Seventy-two alloBMT and 3 autoBMT patients, including ours, were identified. The review suggests that an M2 or M4 French-American-British (FAB) phenotype, intermediate cytogenetic risk group, and chromosome 8 abnormalities are more frequently associated with the occurrence of IEMR. IEMR occurs earlier in autoBMT than in alloBMT. Combined treatment with radiation and high-dose chemotherapy may be effective. When we searched the European Bone Marrow Transplant Registry (EBMTR) database, we found the incidence of IEMR to be statistically greater in alloBMT than in autoBMT (11% vs. 6%; P = 0.02), but no correlations have been found with the conditioning transplant regimen used. A closer follow-up, including body and central nervous system scan, should be considered in patients who are undergoing BMT presenting with several IEMR-associated factors.

Myeloablative conditioning regimens for AML allografts: 30 years later

During the last three decades, several myeloablative conditioning regimens have been used for AML allografts. In this review, we systematically examine the data from studies reporting on myeloablative conditioning regimens for AML allografts. High-dose busulfan combined with cyclophosphamide (BuCy) and cyclophosphamide in combination with total body irradiation (CyTBI) are the two most commonly used conditioning regimens for AML allografts. From the available data, there are no significant differences in survival with these two regimens. A small benefit of decreased relapse rate with CyTBI is counterbalanced by a nonsignificant increase in treatment-related mortality. The incidence of veno-occlusive disease is significantly higher in patients treated with BuCy. Therapeutic monitoring of busulfan was not reported in any of the studies comparing the regimens. Either of the regimens can be used for AML allografts, and the choice may ultimately depend on local availability and expertise. Further improvements may be possible from modifications of the standard regimens. Data from these latter studies seem to be encouraging, but are not based on comparative randomized trials.

Bone marrow vs extramedullary relapse of acute leukemia after allogeneic hematopoietic cell transplantation: risk factors and clinical course

A total of 118 consecutive adult patients with acute leukemia (78 AML, 36 ALL, and four acute mixed lineage leukemia) underwent allogeneic hematopoietic cell transplantation (HCT) after conditioning with BuCy (n=113) or a nonmyeloablative regimen of busulfan-fludarabine (n=5). After a median follow-up of 35.8 months (range, 6.4-91.0), 34 patients experienced at least one episode of leukemia relapse. Of 34 initial episodes, 14 (41%) occurred in extramedullary sites, with (n=8) or without (n=6) concomitant bone marrow involvement. The median time to relapse in the extramedullary sites was longer than that of relapse in bone marrow only (13.5 vs 6.1 months, P=0.046). Acute leukemia subtype and disease status at HCT showed an independent predictive value for overall relapse, as well as for extramedullary relapse with or without bone marrow involvement (Philadelphia chromosome positive acute leukemia vs low-risk AML, relative risk 22.68 (95% CI, 2.18-235.64); other than first CR vs first CR, relative risk 5.61 (95% CI, 1.80-17.51)), but not for bone marrow relapse. Our study suggests that there may be different pathogenetic mechanisms for bone marrow vs extramedullary relapse of acute leukemia after allogeneic HCT. The mode of relapse needs to be investigated in future reports of acute leukemia treated with allogeneic HCT.

Hematopoietic stem cell transplantation: the Vancouver experience

Hematopoietic stem cell transplantation has been available as a therapeutic modality for selected adult patients in Vancouver, British Columbia since 1981. We report on the history, progress, and future prospects of the Leukemia/Bone Marrow Transplantation Program of British Columbia. The basic mechanisms and indications for hematopoietic stem cell transplantation are outlined. Limitations of this procedure are also examined, particularly that of associated toxicities such as graft-versus-host-disease.

Unusual presentation of central nervous system relapse with oculomotor nerve palsy in a case of CD56-positive acute myeloid leukemia following allogeneic stem cell transplantation

Allogeneic stem cell transplantation (allo-SCT) plays an important role in the treatment of infants and children with acute myelogenous leukemia (AML). Leukemic relapse after allo-SCT is responsible for a high rate of treatment failure. Extra-medullary relapse (EMR), without involvement of bone marrow, is rare compared to medullary relapse. CD56, the neural cell adhesion molecule, may contribute to the higher frequency of CNS relapse in CD56-positive AML. We observed an isolated EMR on the oculomotor nerve of a 17-month-old girl 12 weeks after cord blood transplantation (CBT), who was transplanted because of CD56-positive AML. Diagnosis of relapse was suspected clinically and confirmed by magnetic resonance imaging (MRI), and fluorescence-activated cell sorter (FACS) and chimerism analysis of cerebrospinal fluid (CSF). Therapy consisted of intra-thecal chemotherapy, CNS irradiation, and systemic immunomodulation by cyclosporin A (CsA) and basiliximab withdrawal. Twenty-one months after relapse, the patient shows full remission of symptoms and previously described oculomotor nerve infiltration.

Isolated myelosarcoma in children--update and review

Primary myelosarcomas, also called leukemia cutis, granulocytic sarcomas or chloromas, are rare extramedullary manifestations of acute myeloid leukemia (AML) which precede bone marrow involvement. Skin infiltration was the most frequent localization associated with a myelomonocytic differentiation. Although first remission was achieved by most children, risk of relapse seemed to be increased. This might be caused by the specific biology of myelosarcomas, but also may be the result of delayed or reduced treatment. During the AML-BFM-studies 87/93/98 (11/1987-7/2000) 37 children with isolated myelosarcomas were diagnosed. Eighteen of the 37 patients survived with a 5-year overall survival estimation of 0.54+/-0.09 compared to 0.59+/-0.02; p(log rank) = 0.94. However, reduced or delayed treatment in 17 children led to an increased relapse rate of 71% compared to 35% in children treated soon after diagnosis. The 5-year overall survival in these patients was 0.41+/-0.11. According to our experience and review of the literature, an early diagnostic workup is needed in children with unusual skin lesions or tumors, considering myelosarcoma as primary manifestation of AML. Intensive AML-specific chemotherapy is generally recommended soon after diagnosis.

Extramedullary relapse after allogeneic bone marrow transplantation for haematological malignancy

We describe the risk factors for and the natural history and response to treatment of extramedullary (EM) relapse in 183 patients who underwent allogeneic bone marrow transplantation (alloBMT) for a variety of haematological malignancies at our institution over a 7 1/2 year period. Fifty-one patients relapsed; 15 had EM relapse either alone or in association with marrow involvement. A retrospective analysis found that the presence of chronic GVHD and a longer interval between transplant and relapse were independently associated with an increased risk of EM compared to marrow-only relapse. EM relapse was also associated with a longer post-relapse survival. Patients with EM relapse appeared to respond to cytotoxic therapy but not to DLI. EM relapse after alloBMT may be more common than previously thought and have a better prognosis than marrow-only relapse. While patients developing chronic GVHD after alloBMT have a lower overall relapse risk than those who do not, they may be more prone to delayed relapse at EM sites.

High frequency of extramedullary relapse of acute leukemia after allogeneic bone marrow transplantation

We investigated the frequency and mode of relapses of acute leukemia after allogeneic BMT in a series of 50 consecutive patients. The median age of patients was 31.5 years with 26 males. Thirty-two patients had AML. Forty-three patients were in first CR. All patients received BuCy regimen with GVHD prophylaxis of cyclosporine plus methotrexate. After a median follow-up time of 22.4 months (range, 6.0-52.9), 14 patients (28%) relapsed. Seven patients (50%) relapsed in the bone marrow only; three (21%) relapsed in extramedullary sites only; and four (29%) relapsed in both extramedullary sites and bone marrow. Times to relapses in bone marrow only (median 6.3 months) were significantly shorter when compared to times to extramedullary relapses with or without bone marrow involvement (median 12.3 months, P = 0.048). Sites of extramedullary relapses varied widely among the patients. In conclusion, we observed a high frequency of extramedullary relapses of acute leukemia after allogeneic BMT (50%). The GVL effect observed in the extramedullary sites of the body may not be as effective as in the bone marrow in patients with acute leukemia after allogeneic BMT.

Extra-medullary relapse of leukemia following allogeneic bone marrow transplantation

The curative effect of allogeneic bone marrow transplantation (BMT) for acute and chronic leukemia is attributed to the intensive conditioning chemotherapy with or without radiotherapy, as well as an immune-mediated graft versus leukemia (GVL) effect. A different pattern of relapse has been observed after allogeneic BMT for patients with leukemia. Compared with treatment using conventional chemotherapy alone, isolated extra-medullary relapse of disease appears to be seen more commonly after allogeneic BMT. While a full donor's hematopoiesis may be retained, prolonged morphological remission has been observed in the recipient's bone marrow. There appears to be a population of leukemic cells with an affinity to extra-medullary tissues. The failure of the leukemic clone to repopulate the recipient's marrow suggests the presence of a more profound GVL effect in the marrow environment. The optimal treatment for extra-medullary relapse of leukemia following allogeneic BMT remains uncertain. In the case of isolated extra-medullary relapses following BMT, the leukemia may still be responsive to further treatment with chemotherapy and/or radiotherapy. The prognosis is poor in general, but prolonged survival has been observed in some of these patients. With the preservation of donor's hematopoiesis in the recipient's marrow, the use of intensive chemotherapy followed by donor lymphocyte or stem cell re-infusion is a promising option.