Advances in stem cell transplantation: making it better and safer

Enhancing the Activation and Releasing the Brakes: A Double Hit Strategy to Improve NK Cell Cytotoxicity Against Multiple Myeloma

Natural killer (NK) cells are innate lymphocytes with a strong antitumor ability. In tumor patients, such as multiple myeloma (MM) patients, an elevated number of NK cells after stem cell transplantation (SCT) has been reported to be correlated with a higher overall survival rate. With the aim of improving NK cell use for adoptive cell therapy, we also addressed the cytotoxicity of patient-derived, cytokine-stimulated NK cells against MM cells at specific time points: at diagnosis and before and after autologous stem cell transplantation. Remarkably, after cytokine stimulation, the patients' NK cells did not significantly differ from those of healthy donors. In a small cohort of MM patients, we were able to isolate autologous tumor cells, and we could demonstrate that IL-2/15 stimulated autologous NK cells were able to significantly improve their killing capacity of autologous tumor cells. With the aim to further improve the NK cell killing capacity against MM cells, we investigated the potential use of NK specific check point inhibitors with focus on NKG2A because this inhibitory NK cell receptor was upregulated following ex vivo cytokine stimulation and MM cells showed HLA-E expression that could even be increased by exposure to IFN-γ. Importantly, blocking of NKG2A resulted in a significant increase in the NK cell-mediated lysis of different MM target cells. Finally, these results let suggest that combining cytokine induced NK cell activation and the specific check point inhibition of the NKG2A-mediated pathways can be an effective strategy to optimize NK cell therapeutic approaches for treatment of multiple myeloma.

Dyslipidemia and lipid-lowering treatment in a hematopoietic stem cell transplant cohort: 25 years of follow-up data

BACKGROUND

Dyslipidemia is common after hematopoietic stem cell transplantation (HSCT). Few data regarding the time course of lipid profiles after HSCT, the effect of multiple transplantations, and efficacy and safety of lipid-lowering treatments are available.

OBJECTIVE

The objective of the study was to determine the prevalence and treatment of dyslipidemia over a 25-year period in a large, single-center cohort.

METHODS

One thousand one hundred ninety-six adult patients (≥16 years) who underwent HSCT during 1973 to 2013 and who survived ≥100 days were studied retrospectively.

RESULTS

The prevalence of dyslipidemia before transplantation was 36% and 28% in the autologous and allogeneic groups, respectively (P < .001). Three months after HSCT, the prevalence rose to 62% and 74% (P < .001), and at 25 years, it was 67% and 89%. Lipid profiles were similar after first and subsequent transplants. Baseline dyslipidemia (odds ratio [OR] = 2.72), allogeneic transplant (OR = 2.44), and age ≥ 35 years (OR = 2.33) were independent risk factors for dyslipidemia at 1 year. Lipid-lowering treatment was given to 223 (19%) patients, primarily in the form of statins (86%) and was associated with a decrease in total cholesterol from 246 to 192 mg/dL (P < .01) and from 244 to 195 mg/dL (P < .001) in the autologous and allogeneic groups, respectively. There were 10 cases (4%) of muscle symptoms prompting cessation of lipid-lowering therapy, including 1 case of rhabdomyolysis. The OR for dyslipidemia among patients who suffered a cardiovascular event (conditional logistic regression) was 3.5 (95% confidence interval = 1.6-7.7, P = .002).

CONCLUSION

This study confirms that dyslipidemia is a common and long-lasting phenomenon among both allogeneic and autologous HSCT patients. Statins are effective, generally well-tolerated and should be highly recommended for the management of post-HSCT dyslipidemia.

Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies

Despite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA-alkylating agent-based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre-clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA-alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information-backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety.