Allogeneic hematopoietic cell transplantation outcomes for children with B-precursor acute lymphoblastic leukemia and early or late BM relapse.

Large registry studies have shown superior disease-free survival (DFS) with matched sibling donor (MSD) allogeneic hematopoietic cell transplantation (allo-HCT) over chemotherapy alone for patients with B-precursor acute lymphoblastic leukemia (ALL) and a late BM relapse. As most of these patients will not have an MSD, the decision to pursue an unrelated allo-HCT in second remission (CR2) or await a future relapse and perform HCT in third remission (CR3) continues to be debated. Between 1990 and 2006, 41 children with relapsed B-precursor ALL received a myeloablative allo-HCT at the University of Minnesota. Graft sources consisted of matched related donor (n=11), matched unrelated donor (n=9), and unrelated umbilical cord blood (n=21). Before allo-HCT, 15 patients had an early relapse (<36 months from diagnosis) and 26 had an initial late relapse (36 months from diagnosis). In all, 30 patients (73%) were in CR2 and 11 were in CR3 (27%) at time of allo-HCT. Five year OS/DFS were similar for patients with an early or late marrow relapse, but there was inferior DFS among late-relapse patients transplanted in CR3 compared with CR2 (30% vs 75%, P=0.04). These results suggest that allo-HCT should be pursued in children after a first marrow relapse, rather than waiting for subsequent recurrence.

Autologous stem cell transplantation for high-risk Ewing's sarcoma and other pediatric solid tumors.

The prognosis for many pediatric and young adult patients with solid tumors that have metastasized at the time of diagnosis or have relapsed after therapy remains very poor. The steep dose-response curve of many of these tumors to alkylating agents makes myeloablative chemotherapy followed by autologous stem cell transplantation (ASCT) an attractive potential therapy. The role of ASCT for these high-risk patients is yet to be conclusively determined. We have transplanted 36 patients on two consecutive protocols with a variety of histological diagnoses. Overall survival (OS) was 63% (95% CI: 47-79%) at 1 year and 33% (95% CI: 16-50%) at 3 years. Patients with a diagnosis of Ewing's sarcoma (ES) or desmoplastic small round cell tumor (DSRCT) had significantly better survival than those with other diagnoses with estimated 3-year OS of 54% (95% CI: 29-79%) for this group of patients (P = 0.03). There were two transplant-related deaths both attributable to hepatic veno-occlusive disease. Median follow-up among survivors is 3.5 years (range: 0.6-7.9 years). These data justify continued investigation of ASCT as a consolidation therapy in patients with metastatic or relapsed ES and DSRCT.

Role of high-dose chemotherapy with hematopoietic stem cell rescue in the treatment of metastatic or recurrent rhabdomyosarcoma.

PURPOSE: This review summarizes the published data on the use of high-dose chemotherapy and hematopoietic stem cell rescue (HSCR) in the treatment of recurrent or metastatic rhabdomyosarcoma (RMS). PATIENTS AND METHODS: Three hundred eighty-nine patients were identified from 22 articles selected by computer generated searching of MEDLINE (1979-present). One hundred seventy-seven patients had stage 4 disease and were treated during first complete remission (CRI). The remaining patients were treated during CR1/first partial remission (PR1) (110 patients), CR2/PR2 (53 patients), CR2 (12 patients), CR3 (1 patient), or treated with disease (36 patients). RESULTS: Patients treated during CR1 or CR1/PR1 had event-free survival (EFS) rates ranging from 24% to 29% at 3 to 6 years from diagnosis and overall survival (OS) rates ranging from 20% to 40% at 2 to 6 years after diagnosis according to data provided as Kaplan-Meier estimates. Studies without Kaplan-Meier estimates (n = 32) indicate that 12 patients (38%) with stage IV RMS treated during CR1 or CR1/PR1 were surviving 7 to 60 months from diagnosis, similar to patients with stage IV RMS treated on Intergroup Rhabdomyosarcoma Studies II or III. Patients treated during CR2, CR3, or with evidence of disease had a worse outcome with an estimated 3 years OS of 12% (n = 51). Studies without Kaplan-Meier estimates (n = 27) indicate that four patients (15%) treated during CR2, CR3, or with disease were surviving 17 to 33 months after transplant. CONCLUSIONS: Based on these data, there does not appear to be a significant advantage to undergoing high-dose chemotherapy with HSCR for patients with relapsed or refractory high-risk RMS. Clearly, there is a need for incorporating new treatment strategies for patients with high-risk RMS.

In vitro tumor-pulsed or in vivo Flt3 ligand-generated dendritic cells provide protection against acute myelogenous leukemia in nontransplanted or syngeneic bone marrow-transplanted mice.

To determine whether immune stimulation could reduce acute myelogenous leukemia (AML) lethality, dendritic cells (DCs) were pulsed with AML antigens and used as vaccines or generated in vivo by Flt3 ligand (Flt3L), a potent stimulator of DC and natural killer (NK) cell generation. Mice were then challenged with AML cells. The total number of splenic anti-AML cytotoxic T-lymphocyte precursors (CTLPs) present at the time of challenge was increased 1.9-fold and 16.4-fold by Flt3L or DC tumor vaccines, respectively. As compared with the 0% survival of controls, 63% or more of recipients of pulsed DCs or Flt3L survived long term. Mice given AML cells prior to DC vaccines or Flt3L had only a slight survival advantage versus non-treated controls. NK cells or NK cells and T cells were found to be involved in the antitumor responses of Flt3L or DCs, respectively. DC vaccines lead to long-term memory responses but Flt3L does not. Syngeneic bone marrow transplantation (BMT) recipients were analyzed beginning 2 months post-BMT. In contrast to the uniform lethality in BMT controls given AML cells, recipients of either Flt3L or DC vaccines had a significant increase in survival. The total number of splenic anti-AML CTLPs at the time of AML challenge in BMT controls was 40% of concurrently analyzed non-BMT controls. Flt3L or DC vaccines increased the total anti-AML CTLPs 1.4-fold and 6.8-fold, respectively. Neither approach was successful when initiated after AML challenge. It was concluded that DC vaccines and Flt3L administration can enhance an AML response in non-transplanted or syngeneic BMT mice but only when initiated prior to AML progression.

Retinoblastoma and Hirschsprung disease in a patient with interstitial deletion of chromosome 13.

Retinoblastoma is a rare pediatric malignancy (1/20,000) while Hirschsprung disease is a relatively common pediatric disorder (1/5,000). We describe a boy with bilateral retinoblastoma, Hirschsprung disease, multiple minor anomalies, and an interstitial deletion 13q (q13 --> q22). This child and a similar previously reported girl with retinoblastoma and Hirschsprung disease may represent a previously unrecognized contiguous gene syndrome.

Cloning, characterization, and expression in Escherichia coli of the Streptomyces clavuligerus gene encoding deacetoxycephalosporin C synthetase.

Biosynthesis of cephalosporin antibiotics involves an expansion of the five-membered thiazolidine ring of penicillin N to the six-membered dihydrothiazine ring of deacetoxycephalosporin C by a deacetoxycephalosporin C synthetase (DAOCS) enzyme activity. Hydroxylation of deacetoxycephalosporin C to form deacetylcephalosporin C by a deacetylcephalosporin C synthetase (DACS) activity is the next step in biosynthesis of cephalosporins. In Cephalosporium acremonium, both of these catalytic activities are exhibited by a bifunctional enzyme, DAOCS-DACS, encoded by a single gene, cefEF. In Streptomyces clavuligerus, separable enzymes, DAOCS (expandase) and DACS (hydroxylase), catalyze these respective reactions. We have cloned, sequenced, and expressed in E. coli an S. clavuligerus gene, designated cefE, which encodes DAOCS but not DACS. The deduced amino acid sequence of DAOCS from S. clavuligerus (calculated Mr of 34,519) shows marked similarity (approximately 57%) to the deduced sequence of DAOCS-DACS from C. acremonium; however, the latter sequence is longer by 21 amino acid residues.

Cloning and expression in Escherichia coli of isopenicillin N synthetase genes from Streptomyces lipmanii and Aspergillus nidulans.

beta-Lactam antibiotics such as penicillins and cephalosporins are synthesized by a wide variety of microbes, including procaryotes and eucaryotes. Isopenicillin N synthetase catalyzes a key reaction in the biosynthetic pathway of penicillins and cephalosporins. The genes encoding this protein have previously been cloned from the filamentous fungi Cephalosporium acremonium and Penicillium chrysogenum and characterized. We have extended our analysis to the isopenicillin N synthetase genes from the fungus Aspergillus nidulans and the gram-positive procaryote Streptomyces lipmanii. The isopenicillin N synthetase genes from these organisms have been cloned and sequenced, and the proteins encoded by the open reading frames were expressed in Escherichia coli. Active isopenicillin N synthetase enzyme was recovered from extracts of E. coli cells prepared from cells containing each of the genes in expression vectors. The four isopenicillin N synthetase genes studied are closely related. Pairwise comparison of the DNA sequences showed between 62.5 and 75.7% identity; comparison of the predicted amino acid sequences showed between 53.9 and 80.6% identity. The close homology of the procaryotic and eucaryotic isopenicillin N synthetase genes suggests horizontal transfer of the genes during evolution.