A systematic review and network meta-analysis comparing azacitidine and decitabine for the treatment of myelodysplastic syndrome

Are We Ready For "Triplet" Therapy in Higher-Risk MDS?

Higher-risk Myelodysplastic Syndromes/Neoplasms (MDS) represent an ongoing therapeutic challenge, with few effective therapies, many of which may have limited use in this older patient population often with considerations around comorbidities. Outside of transplant, azacitidine and decitabine remain the only disease-modifying therapies, and are palliative in nature. Recent interest has grown in extending combination chemotherapies used to treat acute myeloid leukemia (AML) to patients with MDS, including novel combination chemotherapy "doublets" and "triplets." In this review, we discuss considerations around combination chemotherapy in MDS, specifically as relates to study design, appropriate endpoints, supportive considerations, and how to integrate these into the current treatment paradigm. New therapies in MDS are desperately needed but also require considerations particular to this unique patient population.

Historical expectations with DNA methyltransferase inhibitor monotherapy in MDS: when is combination therapy truly "promising"?

DNA methyltransferase inhibitors (DNMTIs) for patients with higher risk myelodysplastic syndromes (HR-MDS) have low complete remission rates and are not curative. Early DNMTI combination clinical trials in HR-MDS are often termed "promising," but many randomized trials subsequently failed to show benefit. Clearer understanding of when a combination is likely to improve upon DNMTI monotherapy would inform randomized studies. We reviewed MDS azacitidine or decitabine monotherapy studies. We collected baseline demographics including International Prognostic Scoring System (IPSS) risk, DNMTI, disease characteristics; and response variables including survival and marrow and hematologic responses. Aggregate estimates across studies were calculated using meta-analyses techniques. Using a binomial design, we estimated the necessary operating characteristics to design a phase 2 study showing improved efficacy of a combination over monotherapy. Among 1908 patients, the overall response rate (ORR) was 24% (n = 464; 95% confidence interval [CI], 0.22-0.26): 267 complete response (CR, 14%), 68 partial response (4%), and 129 marrow complete remission (7%). Among 1604 patients for whom a hematologic response was reported, 476 (30%; 95% CI, 0.27-0.32) reported hematologic improvement (HI). More patients treated with azacitidine achieved HI (38%; 95% CI, 0.35-0.41) compared with decitabine (15%; 95% CI, 0.13-0.19), whereas the marrow ORR rate was higher with decitabine (29%; 95% CI, 0.26-0.33) compared with azacitidine (21%; 95% CI, 0.19-0.23). CR rates were similar between DNMTIs: 13% with azacitidine and 16% with decitabine. Variables that influence MDS response include the specific DNMTI backbone and the distribution of IPSS risk of patients enrolled on a trial. Considering these factors can help identify which early combination approaches are worth assessing in larger randomized trials.

Comparison Between Decitabine and Azacitidine for Patients With Acute Myeloid Leukemia and Higher-Risk Myelodysplastic Syndrome: A Systematic Review and Network Meta-Analysis

Background: The hypomethylating agents (HMAs) azacitidine (AZA) and decitabine (DAC) have been widely used in patients with acute myeloid leukemia (AML) and higher-risk myelodysplastic syndrome (HR-MDS). However, few direct clinical trials have been carried out to compare the efficacy and adverse events (AEs) between these two agents. The clinical choice between them is controversial. A systematic review and network meta-analysis (NMA) was performed to compare the efficacy, safety, and survival of DAC and AZA in AML and HR-MDS patients.

Methods: We systematically searched MEDLINE, Embase, Web of Science, and Cochrane Library through March 15, 2021. Randomized controlled trials (RCTs) on AML or HR-MDS patients comparing the efficacy and safety between DAC and AZA or comparing one of HMAs to conventional care regimens (CCR) were selected.

Results: Eight RCTs (n = 2,184) were identified in the NMA. Four trials compared AZA to CCR, and four compared DAC to CCR. Direct comparisons indicated that, compared to CCR, both AZA and DAC were associated with higher overall response (OR) rate (AZA vs. CCR: relative risk (RR) = 1.48, 95% CI 1.05–2.1; DAC vs. CCR: RR = 2.14, 95% CI 1.21–3.79) and longer overall survival (OS) (AZA vs. CCR: HR = 0.64, 95% CI 0.50–0.82; DAC vs. CCR: HR = 0.84, 95% CI 0.72–0.98), and AZA showed higher rate of complete remission with incomplete blood count recovery (CRi) (HR = 2.52, 95% CI 1.27–5). For the indirect method, DAC showed a higher complete remission (CR) rate than AZA in patients with both AML (RR = 2.28, 95% CI 1.12–4.65) and MDS (RR = 7.57, 95% CI 1.26–45.54). Additionally, DAC significantly increased the risk of 3/4 grade anemia (RR = 1.61, 95% CI: 1.03–2.51), febrile neutropenia (RR = 4.03, 95% CI: 1.41–11.52), and leukopenia (RR = 3.43, 95% CI 1.64–7.16) compared with AZA. No statistical significance was found for the other studied outcomes.

Conclusion: Compared to CCR, both AZA and DAC can promote outcomes in patients with AML and HR-MDS. DAC showed higher efficacy especially CR rate than AZA (low-certainty evidence), while AZA experienced lower frequent grade 3/4 cytopenia than patients receiving DAC treatment.

Hypomethylating Chemotherapeutic Agents as Therapy for Myelodysplastic Syndromes and Prevention of Acute Myeloid Leukemia

Myelodysplastic Syndromes (MDSs) affect the elderly and can progress to Acute Myeloid Leukemia (AML). Epigenetic alterations including DNA methylation and chromatin modification may contribute to the initiation and progression of these malignancies. DNA hypomethylating agents such as decitabine and azacitidine are used as therapeutic treatments and have shown to promote expression of genes involved in tumor suppression, apoptosis, and immune response. Another anti-cancer drug, the proteasome inhibitor bortezomib, is used as a chemotherapeutic treatment for multiple myeloma (MM). Phase III clinical trials of decitabine and azacitidine used alone and in combination with other chemotherapeutics demonstrated their capacity to treat hematological malignancies and prolong the survival of MDS and AML patients. Although phase III clinical trials examining bortezomib's role in MDS and AML patients are limited, its underlying mechanisms in MM highlight its potential as a chemotherapeutic for such malignancies. Further research is needed to better understand how the epigenetic mechanisms mediated by these chemotherapeutic agents and their targeted gene networks are associated with the development and progression of MDS into AML. This review discusses the mechanisms by which decitabine, azacitidine, and bortezomib alter epigenetic programs and their results from phase III clinical trials.

High-dose regimens of hypomethylating agents promote transfusion independence in IPSS lower-risk myelodysplastic syndromes: a meta-analysis of prospective studies

The hypomethylating agents (HMAs) azacytidine (AZA) and decitabine (DAC) are usually administered after the failure of erythropoietin-stimulating agents for lower-risk myelodysplastic syndromes (LR-MDS). However, it is unclear whether one of these HMAs has superior efficacy and safety. This was investigated in the present study by means of a meta-analysis of prospective studies published between January 1990 and July 2020 in PubMed, EMBASE, CENTRAL, and ClinicalTrials.gov databases; 19 studies with 1076 patients were included in the final analysis. The transfusion independence (TI) rate (66.7% [95% confidence interval: 41.7%-87.4%]) was higher with AZA 75 mg/m²/day for 7 days than with other regimens (all p<0.025). The proportion of patients with intermediate-1 risk influenced overall survival (p<0.05). There were no differences in treatment response, survival, and adverse event rates between patients treated with AZA (75 mg/m²/day for 5 days) and DAC (20 mg/m²/day for 3 days), although the latter group had a higher rate of grade 3/4 anemia (15.8% vs 0.0%; p<0.0001) and lower rate of diarrhea/constipation (6.9% vs 25.0%; p=0.002). Thus, both HMAs at high doses achieved reasonable response and TI rates with acceptable side effects, but did not prolong the overall survival in LR-MDS patients.

Decitabine inhibits the proliferation of human T-cell acute lymphoblastic leukemia molt4 cells and promotes apoptosis partly by regulating the PI3K/AKT/mTOR pathway

T cell acute lymphoblastic leukemia (T-ALL) is a highly aggressive hematological cancer; however, there is a lack of effective chemotherapeutic or targeted drugs for the treatment of T-ALL. Decitabine is a DNA demethylation agent but it has not been used for T-ALL treatment. Therefore, the present study aimed to assess the inhibitory effect of decitabine on T-ALL molt4 cells and determine its regulatory role in the PI3K/AKT/mTOR pathway. Molt4 cells were stimulated with decitabine in vitro, after which cell proliferation, apoptosis and cell cycle analyses were performed to assess cell viability. Subcellular morphology was observed using transmission electron microscopy. Expression levels of phosphate and tension homology (PTEN), genes involved in the PI3K/AKT/mTOR pathway and the corresponding downstream genes were analyzed using reverse transcription-quantitative PCR and western blotting. The results showed that decitabine induced apoptosis, inhibited proliferation and arrested molt4 cells in the G₂ phase. Following decitabine intervention, an increase in the number of lipid droplets, autophagosomes and mitochondrial damage was observed. At concentrations of 1 and 10 µM, decitabine downregulated the expression of PI3K, AKT, mTOR, P70S6 and eukaryotic initiating factor 4E-binding protein 1, which in turn upregulated PTEN expression; however, 50 µM decitabine downregulated PTEN levels. Overall, these results demonstrated that decitabine reduced the viability of molt4 cells partly by inhibiting the PI3K/AKT/mTOR pathway via PTEN, especially at low decitabine concentrations.

In MDS, is higher risk higher reward?

Patients with higher-risk myelodysplastic syndrome (HR-MDS) are defined by the original or revised International Prognostic Scoring System and specific genetic features. Treatment of HR-MDS is challenging. Allogeneic hematopoietic stem cell transplantation, the only curative approach, is feasible in a minority of fit or intermediate fitness patients aged <70 to 75 years who are willing to face the risks of the procedure. Response to azacitidine and decitabine, the only approved drugs for HR-MDS and considered the standard of care, is partial and transient in most patients. The development of novel more personalized and efficient drugs is an unmet medical need. During the last decade, there have been substantial advances in understanding the multiple molecular, cellular, and immunological disturbances involved in the pathogenesis of myelodysplastic syndrome. As a result, a number of clinical and translational studies of new more focused treatment approaches for HR-MDS patients are underway. In contrast to acute myeloid leukemia, they have not resulted in any new drug approval. This review addresses the benefits and limitations of current treatment alternatives, offers a practical individualized treatment approach, and summarizes the clinical trials in progress for HR-MDS.

Recent Advances in Use of Topoisomerase Inhibitors in Combination Cancer Therapy

Inhibitors targeting human topoisomerase I and topoisomerase II alpha have provided a useful chemotherapy option for the treatment of many patients suffering from a variety of cancers. While the treatment can be effective in many patient cases, use of these human topoisomerase inhibitors is limited by side-effects that can be severe. A strategy of employing the topoisomerase inhibitors in combination with other treatments can potentially sensitize the cancer to increase the therapeutic efficacy and reduce resistance or adverse side effects. The combination strategies reviewed here include inhibitors of DNA repair, epigenetic modifications, signaling modulators and immunotherapy. The ongoing investigations on cellular response to topoisomerase inhibitors and newly initiated clinical trials may lead to adoption of novel cancer therapy regimens that can effectively stop the proliferation of cancer cells while limiting the development of resistance.

A Dual-Bioresponsive Drug-Delivery Depot for Combination of Epigenetic Modulation and Immune Checkpoint Blockade

Patients with advanced melanoma that is of low tumor-associated antigen (TAA) expression often respond poorly to PD-1/PD-L1 blockade therapy. Epigenetic modulators, such as hypomethylation agents (HMAs), can enhance the antitumor immune response by inducing TAA expression. Here, a dual bioresponsive gel depot that can respond to the acidic pH and reactive oxygen species (ROS) within the tumor microenvironment (TME) for codelivery of anti-PD1 antibody (aPD1) and Zebularine (Zeb), an HMA, is engineered. aPD1 is first loaded into pH-sensitive calcium carbonate nanoparticles (CaCO₃ NPs), which are then encapsulated in the ROS-responsive hydrogel together with Zeb (Zeb-aPD1-NPs-Gel). It is demonstrated that this combination therapy increases the immunogenicity of cancer cells, and also plays roles in reversing immunosuppressive TME, which contributes to inhibiting the tumor growth and prolonging the survival time of B16F10-melanoma-bearing mice.