Prognostic value of indoleamine 2,3 dioxygenase in patients with higher-risk myelodysplastic syndromes treated with azacytidine

Resistance to Hypomethylating Agents in Myelodysplastic Syndrome and Acute Myeloid Leukemia From Clinical Data and Molecular Mechanism

The nucleoside analogs decitabine (5-AZA-dC) and azacitidine (5-AZA) have been developed as targeted therapies to reverse DNA methylation in different cancer types, and they significantly improve the survival of patients who are not suitable for traditional intensive chemotherapies or other treatment regimens. However, approximately 50% of patients have a response to hypomethylating agents (HMAs), and many patients have no response originally or in the process of treatment. Even though new combination regimens have been tested to overcome the resistance to 5-AZA-dC or 5-AZA, only a small proportion of patients benefited from these strategies, and the outcome was very poor. However, the mechanisms of the resistance remain unknown. Some studies only partially described management after failure and the mechanisms of resistance. Herein, we will review the clinical and molecular signatures of the HMA response, alternative treatment after failure, and the causes of resistance in hematological malignancies.

Predicting outcome in higher-risk myelodysplastic syndrome patients treated with azacitidine

5-Azacitidine (5-AZA) is widely used for the treatment of higher-risk myelodysplastic syndromes. However, response and survival rates vary considerably, while indicated treatment duration remains undefined. For these reasons, factors determining response and survival are of major importance. Clinical, morphological, flow cytometry, cytogenetic and molecular factors are discussed in this review. Biomarkers predictive of response and prognosis, as well as their link to the mode of action of 5-AZA are also addressed, shifting the focus from clinical practice to investigational research. Their use could further improve prognostic classification of 5-AZA treated higher-risk myelodysplastic syndromes in the near future.

A phase 1b/2 study of azacitidine with PD-L1 antibody avelumab in relapsed/refractory acute myeloid leukemia

BACKGROUND

Patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) have limited treatment options. In preclinical models of AML, inhibition of the PD-1/PD-L1 axis demonstrated antileukemic activity. Avelumab is an anti-PD-L1 immune checkpoint inhibitor (ICI) approved in multiple solid tumors. The authors conducted a phase 1b/2 clinical trial to assess the safety and efficacy of azacitidine with avelumab in patients with R/R AML.

METHODS

Patients aged ≥18 years who had R/R AML received azacitidine 75 mg/m² on days 1 through 7 and avelumab on days 1 and 14 of 28-day cycles.

RESULTS

Nineteen patients were treated. The median age was 66 years (range, 22-83 years), 100% had European LeukemiaNet 2017 adverse-risk disease, and 63% had prior exposure to a hypomethylating agent. Avelumab was dosed at 3 mg/kg for the first 7 patients and at 10 mg/kg for the subsequent 12 patients. The most common grade ≥3 treatment-related adverse events were neutropenia and anemia in 2 patients each. Two patients experienced immune-related adverse events of grade 2 and grade 3 pneumonitis, respectively. The overall complete remission rate was 10.5%, and both were complete remission with residual thrombocytopenia. The median overall survival was 4.8 months. Bone marrow blasts were analyzed for immune-related markers by mass cytometry and demonstrated significantly higher expression of PD-L2 compared with PD-L1 both pretherapy and at all time points during therapy, with increasing PD-L2 expression on therapy.

CONCLUSIONS

Although the combination of azacitidine and avelumab was well tolerated, clinical activity was limited. High expression of PD-L2 on bone marrow blasts may be an important mechanism of resistance to anti-PD-L1 therapy in AML.

LAY SUMMARY

This report describes the results of a phase 1b/2 study of azacitidine with the anti-PD-L1 immune checkpoint inhibitor avelumab for patients with relapsed/refractory acute myeloid leukemia (AML). The clinical activity of the combination therapy was modest, with an overall response rate of 10.5%. However, mass cytometry analysis revealed significantly higher expression of PD-L2 compared with PD-L1 on AML blasts from all patients who were analyzed at all time points. These data suggest a novel potential role for PD-L2 as a means of AML immune escape.

Targeting Amino Acid Metabolic Vulnerabilities in Myeloid Malignancies

Tumor cells require a higher supply of nutrients for growth and proliferation than normal cells. It is well established that metabolic reprograming in cancers for increased nutrient supply exposes a host of targetable vulnerabilities. In this article we review the documented changes in expression patterns of amino acid metabolic enzymes and transporters in myeloid malignancies and the growing list of small molecules and therapeutic strategies used to disrupt amino acid metabolic circuits within the cell. Pharmacological inhibition of amino acid metabolism is effective in inducing cell death in leukemic stem cells and primary blasts, as well as in reducing tumor burden in in vivo murine models of human disease. Thus targeting amino acid metabolism provides a host of potential translational opportunities for exploitation to improve the outcomes for patients with myeloid malignancies.

Bone marrow dendritic cell aggregates associate with systemic immune dysregulation in chronic myelomonocytic leukemia

Systemic immune microenvironment signatures in CMML indicate an altered T- and natural killer cell balance. CMML bone marrow dendritic cell aggregates associate with disease progression and systemic regulatory T-cell phenotypic switch.

Phenotypic characterization of leukemia-initiating stem cells in chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a stem cell-derived neoplasm characterized by dysplasia, uncontrolled expansion of monocytes, and substantial risk to transform to secondary acute myeloid leukemia (sAML). So far, little is known about CMML-initiating cells. We found that leukemic stem cells (LSC) in CMML reside in a CD34⁺/CD38^- fraction of the malignant clone. Whereas CD34⁺/CD38^- cells engrafted NSGS mice with overt CMML, no CMML was produced by CD34⁺/CD38⁺ progenitors or the bulk of CD34^- monocytes. CMML LSC invariably expressed CD33, CD117, CD123 and CD133. In a subset of patients, CMML LSC also displayed CD52, IL-1RAP and/or CLL-1. CMML LSC did not express CD25 or CD26. However, in sAML following CMML, the LSC also expressed CD25 and high levels of CD114, CD123 and IL-1RAP. No correlations between LSC phenotypes, CMML-variant, mutation-profiles, or clinical course were identified. Pre-incubation of CMML LSC with gemtuzumab-ozogamicin or venetoclax resulted in decreased growth and impaired engraftment in NSGS mice. Together, CMML LSC are CD34⁺/CD38^- cells that express a distinct profile of surface markers and target-antigens. During progression to sAML, LSC acquire or upregulate certain cytokine receptors, including CD25, CD114 and CD123. Characterization of CMML LSC should facilitate their enrichment and the development of LSC-eradicating therapies.

Factors affecting response to 5-azacytidine and prognosis of myelodysplastic syndrome. Is long-term survival a realistic goal?

The introduction of hypomethylating agents (HMAs) 5-azacytidine and decitabine has altered the prognosis of patients with myelodysplastic syndrome (MDS). Over the past few years, the International Prognostic Scoring System (IPSS) and the revised IPSS (IPSS-R) have been used both to define the prognosis of patients with MDS and to select patients to be treated with HMAs. Nevertheless, the prognosis of individual patients with MDS can differ considerably from the one calculated with the use of the above-mentioned prognostic systems. Thus, some patients may achieve long-term survival irrespective of their initial prognostic score. Several factors besides those used to define the IPSS/IPSS-R are analyzed in this review article; these include age and gender, the baseline hematologic characteristics, the comorbidities, the cytogenetic and molecular profile of the patients, as well as their response to treatment with 5-azacytidine. Thus, insight into a more personalized way of managing patients with MDS is given and long-term survival is set as a more realistic goal of treatment with 5-azacytidine.

Biochemical phenotyping of multiple myeloma patients at diagnosis reveals a disorder of mitochondrial complexes I and II and a Hartnup-like disturbance as underlying conditions, also influencing different stages of the disease

The aim of this study was to identify novel plasma metabolic signatures with possible relevance during multiple myeloma (MM) development and progression. A biochemical quantitative phenotyping platform based on targeted electrospray ionization tandem mass spectrometry technology was used to aid in the identification of any eventual perturbed biochemical pathway in peripheral blood plasma from 36 MM patients and 73 healthy controls. Our results showed that MM cases present an increase in short and medium/long-chain species of acylcarnitines resembling Multiple AcylCoA Dehydrogenase Deficiency (MADD), particularly, associated with MM advanced International Staging System (ISS). Lipids profile showed lower concentrations of phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and sphingomyelins (SM) in the MM patients and its respective ISS groups. MM cases were accompanied by a drop in the concentration of essential amino acids, especially tryptophan, with a significant inverse correlation between the progressive drop in tryptophan with the elevation of β2-microglobulin, with the increase in systemic methylation levels (Symmetric Arginine Dimethylation, SDMA) and with the accumulation of esterified carnitines in relation to free carnitine (AcylC/C0). Serotonin was significantly elevated in cases of MM, without a clear association with ISS. Kynurenine/tryptophan ratio demonstrates that the activity of dioxigenases is even higher in the cases classified as ISS 3. In conclusion, our study showed that MM patients at diagnosis showed metabolic disorders resembling both mitochondrial complexes I and II and Hartnup-like disturbances as underlying conditions, also influencing different stages of the disease.