Treatment of Elderly Acute Myeloid Leukemia Patients

Immunoliposomes in Acute Myeloid Leukaemia Therapy: An Overview of Possible Targets and Obstacles

Acute Myeloid Leukaemia (AML) is the neoplastic transformation of Hematopoietic Stem Cells (HSC) and relapsed disease is a major challenge in the treatment. Despite technological advances in the field of medicine and our heightened knowledge regarding the pathogenesis of AML, the initial therapy of "7+3" Cytarabine and Daunorubicin has remained mainly unchanged since 1973. AML is a disease of the elderly, and increased morbidity in this patient group does not allow the full use of the treatment and drug-resistant relapse is common. Nanocarriers are drug-delivery systems that can be used to transport drugs to the bone marrow and target Leukemic Stem Cells (LSC), conferring less side-effects compared to the free-drug alternative. Nanocarriers also can be used to favour the transport of drugs that otherwise would not have been used clinically due to toxicity and poor efficacy. Liposomes are a type of nanocarrier that can be used as a dedicated drug delivery system, which can also have active ligands on the surface in order to interact with antigens on the target cells or tissues. In addition to using small molecules, it is possible to attach antibodies to the liposome surface, generating so-called immunoliposomes. By using immunoliposomes as a drug-delivery system, it is possible to minimize the toxic side effects caused by the chemotherapeutic drug on healthy organs, and at the same time direct the drugs towards the remaining AML blasts and stem cells. This article aims to explore the possibilities of using immunoliposomes as a drug carrier in AML therapy. Emphasis will be on possible target molecules on the AML cells, leukaemic stem cells, as well as bone marrow constituents relevant to AML therapy. Further, some conditions and precautions that must be met for immunoliposomes to be used in AML therapy will be discussed.

Outcomes of Allogeneic Stem Cell Transplantation in Elderly Patients with Acute Myeloid Leukemia: A Systematic Review and Meta-analysis

A large number of elderly patients with acute myeloid leukemia (AML) are not offered treatments with curative intent, such as allogeneic stem cell transplantation (SCT), because of fears of toxicity and perceived futility of intensive treatment. Therefore, the outcomes of SCT in elderly AML patients remain poorly defined. We performed a meta-analysis of all previous articles up until September 22, 2015 of SCT in AML patients >60 years. The primary endpoints were relapse-free survival (RFS) and overall survival (OS) at 6 months and at 1, 2, and 3 years. A total of 13 studies (749 patients) were included. The pooled estimates and 95% confidence intervals (CI) for RFS at 6 months, 1 year, 2 years, and 3 years were 62% (95% CI, 54% to 69%), 47% (95% CI, 42% to 53%), 44% (95% CI, 33% to 55%), and 35% (95% CI, 26% to 45%), respectively. The corresponding numbers for OS were 73% (95% CI, 66% to 79%), 58% (95% CI, 50% to 65%), 45% (95% CI, 35% to 54%), and 38% (95% CI, 29% to 48%), respectively. We found no evidence of publication bias in our primary endpoints, with the exception of relapse, where there appeared to be a relative lack of small studies with high relapse rates. Sensitivity analysis did not identify an overtly influential study for our primary endpoints, with 1 exception in 2-year RFS analysis. The present analysis argues against significant publication bias and demonstrates consistency among reports despite differences in patient-, disease-, center-, and transplantation-related characteristics. Our results suggest that reduced-intensity SCT is a viable treatment option for elderly AML patients with a 3-year RFS of 35% for those over the age of 60. These results argue against using age per se as the sole criterion against SCT and would help remove some of the barriers that often preclude curative intent treatment. Correct identification of patients who would benefit from SCT can improve outcomes in this frequently undertreated population.

Paraptosis cell death induction by the thiamine analog benfotiamine in leukemia cells

Benfotiamine is a synthetic thiamine analogue that stimulates transketolase, a cellular enzyme essential for glucose metabolism. Currently, benfotiamine is used to treat diabetic neuropathy. We recently reported that oral benfotiamine induced a temporary but remarkable recovery from acute myeloid leukemia in an elderly patient who was ineligible for standard chemotherapy due to dementia and renal failure. In the present study we present evidences that benfotiamine possess antitumor activity against leukemia cells. In a panel of nine myeloid leukemia cell lines benfotiamine impaired the viability of HL-60, NB4, K562 and KG1 cells and also inhibited the growing of primary leukemic blasts. The antitumor activity of benfotiamine is not mediated by apoptosis, necrosis or autophagy, but rather occurs though paraptosis cell death induction. Mechanistic studies revealed that benfotiamine inhibited the activity of constitutively active ERK1/2 and concomitantly increased the phosphorylation of JNK1/2 kinase in leukemic cells. In addition, benfotiamine induced the down regulation of the cell cycle regulator CDK3 which resulted in G1 cell cycle arrest in the sensitive leukemic cells. Moreover, combination index studies showed that benfotiamine enhanced the antiproliferative activities of cytarabine against leukemia cells. These findings suggest that benfotiamine has antitumor therapeutic potential.

Iodinin (1,6-dihydroxyphenazine 5,10-dioxide) from Streptosporangium sp. induces apoptosis selectively in myeloid leukemia cell lines and patient cells

Despite recent improvement in therapy, acute myeloid leukemia (AML) is still associated with high lethality. In the presented study, we analyzed the bioactive compound iodinin (1,6-dihydroxyphenazine 5,10-dioxide) from a marine actinomycetes bacterium for the ability to induce cell death in a range of cell types. Iodinin showed selective toxicity to AML and acute promyelocytic (APL) leukemia cells, with EC50 values for cell death up to 40 times lower for leukemia cells when compared with normal cells. Iodinin also successfully induced cell death in patient-derived leukemia cells or cell lines with features associated with poor prognostic such as FLT3 internal tandem duplications or mutated/deficient p53. The cell death had typical apoptotic morphology, and activation of apoptotic signaling proteins like caspase-3. Molecular modeling suggested that iodinin could intercalate between bases in the DNA in a way similar to the anti-cancer drug daunorubicin (DNR), causing DNA-strand breaks. Iodinin induced apoptosis in several therapy-resistant AML-patient blasts, but to a low degree in peripheral blood leukocytes, and in contrast to DNR, not in rat cardiomyoblasts. The low activity towards normal cell types that are usually affected by anti-leukemia therapy suggests that iodinin and related compounds represent promising structures in the development of anti-cancer therapy.