Patients and methods

Patients

All patients included in this report were transplanted by the Pediatric Bone Marrow Transplant (BMT) Program of the University of Colorado School of Medicine based at The Children's Hospital, Denver or by the Pediatric BMT Program of Northwestern University based at Children's Memorial Hospital, Chicago. All families provided signed, informed consent for their children's transplants, including the option to analyze and report the outcomes of their treatment. This report includes all patients with monosomy 7 AML and MDS transplanted at The Children's Hospital between January 1994, when the program opened, and March 2003 and at Children's Memorial Hospital between March 1992, when that program opened, and March 2003. Data for this study were extracted from the Pediatric BMT Program Databases at the two institutions.

A total of 16 patients with monosomy 7 and AML or MDS underwent allogeneic HSCT from 1992 to 2003 at The Children's Hospital (TCH) in Denver, Colorado and Children's Memorial Hospital (CMH) in Chicago, Illinois. Primary diagnoses were MDS (N=5), therapy-related MDS (N=3), AML (N=5) and therapy-related AML (N=3). Clinical details, leukemia and MDS subclassifications and complete cytogenetic results are presented in Tables 1 and 2. There were eight female and eight male patients. Median age at diagnosis was 64.5 months (range, 12 to 199 months). Median age at hematopoietic stem cell transplant (HSCT) was 69.5 months (range, 27 to 207 months). Median interval from diagnosis to transplantation was 8 months (range, 2 to 49 months). In all, 11 patients had complete loss of one copy of chromosome 7, while five patients had partial loss of 7q. Deletion of 7q31 sequences was documented by fluorescent in situ hybridization (FISH) studies for all TCH patients except UPIN#67. The chromosome 7 breakpoint in that case was distal to the region recognized by the probe. FISH studies were not conducted on any of the CMH patients.

Table 1 - (a) Patient data and (b) outcome data.

Full table

Table 2 - Cytogenetic results.

Full table

Nine of the patients were treated pre-transplant with conventional dose induction therapy appropriate to the patient's marrow disorder (MDS, AML). For AML patients, central nervous system prophylaxis was with intrathecal AraC. Patients were transplanted in first complete remission (N=3), first relapse (N=1), second complete remission (N=1), ongoing MDS (N=7), induction failure (N=3) and third relapse (N=1). Conditioning regimens were total body irradiation (TBI) with cyclophosphamide (CTX; 45 mg/kg/day intravenously for 2 days) and AraC (2.0–2.5 g/m²/dose intravenously every 12 h for six doses over 3 days) in seven patients; busulfan and CTX in two patients; TBI with CTX (60 mg/kg/day intravenously for 3 days) and etoposide (VP, 1000 mg/m²/day intravenously for one dose) in four patients; busulfan (1 mg/kg/dose every 6 h intravenously for 16 doses)/CTX (60 mg/kg/day intravenously for 3 days) with VP (1000 mg/m²/day intravenously for one dose) in one patient; fludarabine (25 mg/m²/day intravenously for 6 days) with busulfan (1 mg/kg every 6 h intravenously for eight doses) in one patient and busulfan/CTX for initial transplant followed by nonmyeloablative AraC with asparaginase at recurrence in one patient. In the TBI-containing regimens, radiation was delivered to a total dose of 1200 cGy (six fractions at TCH, eight fractions at CMH) with blocking of the lungs to limit the core dose to 900 cGy and a 400 cGy testicular boost in boys (at TCH) with acute leukemia. Busulfan/CTX conditioning and AraC/asparaginase (Capizzi regimen) were given as previously described.^7,8

Donor types and stem cell sources were matched sibling marrow (MS BMT; N=3), matched sibling cord blood (MS CB; N=1), matched sibling peripheral blood stem cells (N=3), mismatched related marrow (N=1), unrelated marrow (N=2), and unrelated cord blood (UD CB; N=6). The cutoff date for data accrual was March 6, 2003 at The Children's Hospital and Children's Memorial Hospital, at which time event-free survival curves were generated.

Statistical analysis

The event-free survival curves presented in Figure 1 were computed using the method of Kaplan and Meier.⁹ Outcomes were analyzed from the time (day 0) of the patient's most recent hematopoietic stem cell infusion until the time of first subsequent event or, for patients without events, the time of last follow-up. Events in this analysis were defined as disease relapse or progression, death from complication or other cause and graft failure or rejection. Quality of life assessments were conducted using the Lansky or Karnofsky score, as appropriate to patient age.¹⁰

Figure 1.

Monosomy 7 AML and MDS event-free survival after allogeneic HSCT – 11 of 16 patients survive event free with a median follow-up of 986 days (range 330–2011), following allogeneic hematopoietic stem cell transplantation (HSCT) for AML and MDS with monosomy 7.

Full figure and legend (50K)

Specimens

Patient samples (blood and marrow) were obtained at initial diagnosis. Cytogenetic assays were performed in The Colorado Genetics Laboratory and at the Arkansas Children's Hospital Cytogenetics Laboratory using previously described procedures.¹¹ Karyotypes were reviewed by one of the authors (L McGavran) for the patients at TCH and by the Arkansas Children's Hospital Cytogenetics Laboratory for the patients at CMH and were described according to the International System for Cytogenetic Nomenclature.¹²

FISH studies

FISH studies were performed using interphase nuclei and metaphase spreads from uncultured bone marrow samples prepared for cytogenetic analyses. FISH probes were obtained from Vysis, Inc. (Downer's Grove, IL, USA) and consist of alphoid sequences for #7 centromere (D7Z1) and DNA sequences within band 7q31 D7S486, differentially labeled with Spectrum Orange™ and Spectrum Green™, respectively. Hybridization and post-wash procedures followed the manufacturer's protocols. The slides were analyzed using an Olympus BX60 microscope with appropriate fluorescent filters. A minimum of 200 interphase nuclei, counterstained with DAPI (4'6-amidino-2-phenylindole) were scored for the number of centromere and 7q31 signals.

Results

Of 16 patients, 11 survived event-free with a median follow-up in survivors of 986 days (range 330–2011 days) (see Figure 1). Four of four patients with AML transplanted in complete remission and six of seven with MDS are currently alive without evidence of disease and with few chronic complications (see Table 1 and Figure 1). One patient (UPIN 63) with therapy-related AML following treatment for spinal cord sarcoma recurred at 6 months following MS BMT at another center. She was salvaged using an immunotherapeutic strategy. She received non-myeloablative chemotherapy (AraC, asparaginase; Capizzi regimen) plus reinfusion of donor marrow without post-infusion immunosuppression. Following blood count recovery, the patient received a single donor lymphocyte infusion (DLI) of 1 10⁸ CD3+ cells/kg and a 2-year course of low dose, intermittent IL-2 for the purpose of enhancing graft-versus-leukemia effects (GVL).¹³ She is surviving in CR2, 5 years from second donor marrow infusion and 3 years from last antileukemia therapy.

Neutrophil engraftment occurred at a median of 27.5 days (range, day +12 to day +100). Two patients died prior to engraftment. One patient, who received a haploidentical, T-cell-depleted graft from her father, died at day +38 prior to engraftment. One patient died of grade IV mucositis at day +35 prior to engraftment.

Toxicity was responsible for the deaths of the five nonsurviving patients, occurring at a median of 48 days post-HSCT. The three patients with induction failure, one patient with MDS, and the patient transplanted in third relapse all died of complications. Deaths were due to infection (N=2), graft-versus-host disease (GVH; N=1), grade IV mucositis (N=1) and multiorgan failure (N=1). UPIN 78 was transplanted using UD BMT following AML induction failure. She died on day +124 in CR1 with donor engraftment. Death was due to multiorgan failure related to enterobacter sepsis. Prior post-HSCT complications had included Aspergillus pneumonia/cellulitis and CMV pneumonia. UPIN 67 was transplanted in third relapse and died from adenovirus gastroenteritis, stenotrophomonas sepsis and pulmonary hemorrhage on day +38. UPIN 65 had therapy-related AML following treatment for osteosarcoma and was transplanted following induction failure. He developed fatal grade IV GVH of the gastrointestinal tract and liver, which terminally led to severe gastrointestinal and central nervous system hemorrhage. UPIN 99 had therapy-related AML following treatment for acute lymphoblastic leukemia (ALL) and was transplanted following induction failure. She died at day +82 from multiorgan failure related to preparative therapy and without documented infection. UPIN 940012 had therapy-related MDS and died following transplant due to fatal grade IV mucositis at day +35.

Among patients who received matched sibling donor transplants using marrow, peripheral blood stem cells or cord blood, six of seven (86%) survive event-free. Six of the seven (86%) patients who received unrelated cord blood transplants and the one patient who received a matched sibling cord blood transplant are surviving event-free. In addition to the one patient who died following unrelated cord blood transplant, the two patients with an unrelated BMT and the patient with a mismatched related BMT all died of complications. One of the three patients who received matched sibling PBSC died of multiorgan failure. Of the two patients who received matched sibling marrow and the one patient treated with immunotherapy following initially failed matched sibling BMT, all survive event-free. Of the five patients who failed HSCT, three had complete loss and two had partial loss of chromosome 7.

Quality of life assessments in the 11 surviving patients are all high. Performance scores were 90 (N=4) or 100 (N=7) at a median follow-up of 986 days (range 330–2011 days).

Discussion

Monosomy 7 in pediatric patients with AML or MDS is associated with poor event-free survival when treated with conventional chemotherapy. In Table 3, the few studies that report survival results according to therapy in patients with monosomy 7 are listed. Details and patient numbers are limited, and studies often include both pediatric and adult patients. In the current literature, it is difficult to track the management and treatment-related outcomes of these patients, since they are often grouped with other patients with various poor prognosis cytogenetic or clinical features.

Table 3 - Literature review of disease-free survival in pediatric patients with monosomy 7.

Full table

In 2000, Chang et al¹⁵ reported 233 patients with AML on Pediatric Oncology Group Study 8821 who had chromosomal abnormalities other than t(8;21) or inversion 16. Patients with monosomy 7 were not described separately. The patients with chromosomal abnormalities other than t(8;21) or inversion 16 had the lowest event-free survival with 4-year event-free survival of 27.0% compared to 49.3 and 43.1% for those with t(8;21) or inversion 16 and those with normal leukemic karyotype, respectively.

Kardos et al¹⁸ recently reported in 2003 on 67 pediatric patients with refractory anemia. Of these patients, 32 had monosomy 7. At ten years, of 23 patients who underwent allogeneic SCT, 57% survived; whereas, of nine patients who were not transplanted, 33% survived. Although causes of death for the patients with monosomy 7 were not detailed, this series of refractory anemia in pediatric patients suggests that SCT should be considered in these patients.

In 2002, Woods et al²⁰ reported results of Children's Cancer Group study CCG-2891. Of the 1096 enrolled patients, 871 had AML, 23 had t-AML and 16 had MDS, which had progressed to AML. Of the remaining 74 patients with various forms of MDS or juvenile myelomonocytic leukemia (JMML), 13 had JMML, two had refractory anemia (RA), 33 had RA with excess blasts (RAEB) and 26 had RAEB in transformation (RAEBt). Excluding the patients with JMML, 36% of 61 patients with MDS had monosomy 7. In the patients with AML or MDS with progression to AML, 4% of 887 patients had AML with monosomy 7. Patients achieving remission received allogeneic SCT if a matched related donor was available. All others were randomized to receive intensive chemotherapy or autologous SCT. Event-free and overall survival for the 74 patients with MDS/JMML with monosomy 7 was 38 and 54% at 6 years, respectively, not significantly different from survival in patients with MDS/JMML without monosomy 7. In comparison, event-free and overall survival for 15 evaluable patients with monosomy 7 AML was 19 and 47%, respectively. Treatment-related outcomes in the patients with monosomy 7 were not detailed; however, the authors report that overall survival did not vary significantly in AML patients with or without monosomy 7 due to a relatively high salvage rate using unrelated SCT in the patients with monosomy 7.

In 1998, Grimwade et al²¹ reported results of the MRC AML 10 Trial. Among other aspects, this study of adult and pediatric patients with AML analyzed the independent prognostic significance of pretreatment cytogenetics. They reported a relatively favorable outcome for patients with t(8;21), t(15;17) and inversion 16. In contrast, there was a relatively poor outcome for patients with a complex karyotype, complete or partial loss of chromosome 5, loss of chromosome 7 and abnormalities of 3q. In the adverse cytogenetics group, there was a decreased likelihood of achieving complete remission, increased deaths during induction therapy, a higher rate of leukemic relapse and poorer overall survival. There were 61 patients with monosomy 7 (48 de novo AML, 13 with secondary AML). Of the 61 patients with AML with monosomy 7, 54% achieved complete remission, 16% died during induction and 30% had resistant disease. On follow-up, 80% of the monosomy 7 patients who entered CR had relapsed by 5 years from diagnosis. Overall, only 10% of patients with AML and monosomy 7 were alive at 5 years, implying difficulty salvaging patients who failed primary chemotherapy. By comparison, the patients without poor prognosis cytogenetic abnormalities (ie without a complex karyotype, loss of chromosome 5, loss of chromosome 7 or abnormality of 3q) had a 42% overall survival at 5 years.

In a subsequent analysis of the MRC 10 trial by Wheatley et al,¹ among 1711 patients, there were 204 patients in the adverse cytogenetic risk group who received chemotherapy alone as primary treatment. They had 19% survival at 5 years. By comparison, 16 patients underwent allogeneic BMT with 38% survival at 5 years post-transplant. A total of 23 patients underwent autologous BMT with 29% survival at 5 years post-transplant. These results grouped all of the poor prognosis cytogenetic abnormalities and did not separate adult and pediatric patients. Thus, the results of HSCT specific to children with monosomy 7 AML cannot be ascertained from this report.

Webb et al¹⁹ reported 36 children with RAEB and RAEBt, 12 of whom had loss of chromosome 7. Six of the 12 patients had been treated under the AML 10 and AML 12 MRC trials. Of these 12 patients, three underwent allogeneic SCT, six received chemotherapy alone and three received no treatment. One of the three transplanted patients was alive at 2.25 years. Of the two nonsurviving transplanted patients, one died of complications of therapy and one died of disease. Two of the six patients who received chemotherapy alone survived at 8.7 and 4.7 years.

In 1999, Luna-Fineman et al²² evaluated 167 pediatric patients with transient myeloproliferative syndrome with Down's syndrome, MDS or juvenile myelomonocytic leukemia. A total of 53 patients had monosomy 7. Of all the patients, 32% experienced transformation to acute leukemia, usually within 2 years of diagnosis. This provides substance to the belief that monosomy 7 MDS and AML represent a biologic continuum of disease. Of the 167 patients, 116 patients received HSCT (matched sibling, N=86; unrelated donor, N=23; autologous, N=7). Of the 116 patients with MDS who received a transplant, 39% survived at 10 years. The survival of children transplanted with monosomy 7 was not specifically detailed; however, univariant analysis showed no apparent impact of monosomy 7 on post-transplant survival.

The outcomes of 189 pediatric patients in Japan with MDS were reported by Sasaki et al²³ in 2001. A total of 92 patients received HSCT with overall survival ranging from 35 to 100% at 8 years, depending on FAB subclassification. Of the 189 patients, 17 had monosomy 7. Therapy for these 17 patients was not specified. The survival rate for these patients was 0%.

Data on outcome for patients with monosomy 7 AML or MDS treated with chemotherapy are limited; however, it appears to be poor with 0–33% survival in the above trials and others summarized in Table 3. The combined pediatric transplant experience in monosomy 7 AML and MDS obtained from our review of previously published reports was 45 patients, where both specific diagnosis and HSCT could be clearly substantiated. These children were transplanted with varying disease status and using varied donor types. Overall, it appeared that 23 of these 45 had prolonged survival.

Our experience includes 16 patients with AML or MDS with monosomy 7 who were transplanted in various disease states with allogeneic donors of bone marrow, peripheral stem cells or cord blood. Five patients died of transplant-related complications. In all, 11 patients are surviving disease-free with a median follow-up of 986 days post-HSCT (range 330–2011 days). Of 11 patients who were transplanted with MDS or with AML in CR, 10 are surviving event free; in comparison, patients transplanted with active leukemia fared more poorly. Thus, our experience suggests that allogeneic transplantation is more effective than the above summarized chemotherapeutic strategies. This assessment remains limited by the number of patients in our series and suggests the need to clarify optimal therapy for these patients in future prospective trials.

GVL may be a significant factor in curative treatment for at least some patients. This is strongly suggested by our patient (UPIN 63) who relapsed after an initial allogeneic BMT. The patient attained a sustained remission after nonmyeloablative chemotherapy with marrow infusion and DLI without GVH prophylaxis and with possible enhancement of GVL with IL-2 therapy. An additional patient not included in this series further demonstrates the potential impact of GVL in the monosomy 7 disorders. This child, followed at The Children's Hospital in Denver, underwent matched unrelated donor BMT elsewhere for monosomy 7 AML (James Casper, personal communication). He suffered relapse of his AML at 6 months post-BMT. Second remission was obtained with DLI, administered without post-infusion immunosuppression. This patient remains alive and well in CR2, with a Lansky performance score of 90, now 72 months post-DLI.

The prognostic implications of complete vs partial monosomy 7 has been considered in some publications. In the report by Hasle et al,⁴ 3-year survivals of 50% for 63 patients with complete monosomy 7 alone, 42% for 20 patients with complete monosomy 7 with other chromosome abnormalities, 0% for four patients with 7q-, and 35% survival for 13 patients with loss of 7q with other chromosome abnormalities were reported. The increased survival in complete monosomy 7 alone was felt to be only due to improved survival in patients with MDS compared to those with AML. In our study, seven of 10 (70%) patients with complete monosomy 7 survive disease-free compared with four of six (67%) patients with partial loss of monosomy 7. Thus, in the context of currently available therapies, the impact of complete vs partial monosomy 7 on outcome is not yet clear.

In conclusion, our experience indicates that treatment with allogeneic HSCT using a variety of donor types is effective therapy for childhood AML and MDS associated with monosomy 7. Patients with MDS alone and AML in CR appear to benefit most from this approach. Our experience, combined with the other reports reviewed above, appears better than that reported for chemotherapy management of these patients and suggests that allogeneic HSCT should be the therapy of choice for young patients with monosomy 7 AML or MDS. Those patients with advanced or resistant leukemia fared more poorly in our series. It is possible that allogeneic HSCT using different preparative and supportive therapy approaches could further improve disease-free survival in patients with more advanced disease since these patients died from toxicity, but with disease control. GVL appears to play an active role in leukemia control for some patients. Quality of life in surviving patients was very good. Thus, our experience suggests that it is appropriate to consider allogeneic HSCT early in the course of monosomy 7 AML and MDS.

References

References