Non-myeloablative hematopoietic stem cell transplantation is of limited value in advanced or refractory acute myeloblastic leukemia. The Mexican experience

Effects of intensified conditioning on Epstein-Barr virus and cytomegalovirus infections in allogeneic hematopoietic stem cell transplantation for hematological malignancies

BACKGROUND

Intensified conditioning regimens (increasing the intensity of standard myeloablative conditioning) for hematological malignancies in allogeneic hematopoietic stem cell transplantation (allo-HSCT) could reduce the relapse rate of the underlying disease, but it might simultaneously increase the transplant-related mortality including the mortality of infections. To explore whether intensified conditioning affected Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infections, 185 patients undergoing allo-HSCT were enrolled.

METHODS

A total of 104 cases received standard and 81 intensified conditioning. Cyclosporine A (CsA) withdrawal and/or donor lymphocyte infusion (DLI) were conducted in high-risk patients. The EBV-DNA and CMV-DNA levels of blood were monitored regularly by quantitative real-time polymerase chain reaction (RQ-PCR) and immune reconstitution of recipients were analyzed by flow cytometry.

RESULTS

The 3-year cumulative incidence of EBV viremia, EBV-associated diseases and mortality of EBV-associated diseases were 25.3% ± 4.6%, 10.5% ± 3.4% and 0.0% ± 0.0% in the standard group, compared with 45.6% ± 6.5%, 26.0% ±5.3% and 7.3% ± 3.1% in the intensified group (P = 0.002, P = 0.002, P = 0.008). The 3-year cumulative incidence of CMV viremia and CMV-associated diseases, mortality of CMV-associated diseases and incidence of bacterial and fungal infections were similar between the two groups (P = 0.855, P = 0.581, P = 0.933, P = 0.142, P = 0.182, respectively). Multivariate analysis showed that intensified conditioning was one of the risk factors for EBV viremia and EBV-associated diseases (P = 0.037, P = 0.037), but it had no effects on CMV infections. The percentage of CD4+ T cells and CD4+/CD8+ ratio at 3 months post-transplantation were lower in the intensified group (P = 0.032, P = 0.022). The 3-year OS and DFS in the standard group were 62.2% ± 5.8% and 60.6% ± 5.6%, compared with 51.6% ± 6.2% and 51.1% ± 5.9% in the intensified group (P = 0.029, P = 0.063).

CONCLUSIONS

Intensified conditioning represents a promising approach for high-risk hematological malignancies, although it affects early immune reconstitution of recipients and increases the incidence and mortality of EBV infections.

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

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

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

Intermediate intensity conditioning regimen containing FLAMSA, treosulfan, cyclophosphamide, and ATG for allogeneic stem cell transplantation in elderly patients with relapsed or high-risk acute myeloid leukemia

Lower dosage of total body irradiation (TBI) and chemotherapy in reduced-intensity conditioning (RIC) regimens prior to allogeneic stem cell transplantation have reduced the toxicity of the conditioning and non-relapse mortality. The FLAMSA-RIC protocol for high-risk patients with acute myeloid leukemia (AML) and myelodysplastic syndrome has shown promising results in refractory disease as well as in first complete remission. Still, the RIC protocol containing 4 Gy TBI/cyclophosphamide/anti-thymocyte globulin (ATG) implicates acute toxicity mainly due to TBI preventing its usage in patients with advanced age and/or severe co-morbidities. To increase feasibility and safety of the conditioning, we substituted TBI with treosulfan. Seventeen patients with relapsed or high-risk AML and either advanced age or concomitant disease were treated within a preparative regimen containing a 4-day course of chemotherapy (FLAMSA) followed by RIC comprising of treosulfan, cyclophosphamide, and ATG. After median follow-up of 12 months, the estimated incidences of relapse and non-relapse mortality were 25% and 20%, respectively. One-year overall survival was 62%. In conclusion, FLAMSA-treosulfan/cyclophosphamide/ATG is an intermediate intensity conditioning regimen with acceptable non-relapse mortality for patients with relapsed or high-risk AML. Substituting TBI with treosulfan provides an alternative to treat elderly patients or patients with severe co-morbidities when TBI appears not feasible due to the potential of increased toxicity.