Phase I Clinical Trials in Acute Myeloid Leukemia: 23-Year Experience From Cancer Therapy Evaluation Program of the National Cancer Institute

Recent Developments and Future Perspectives of Purine Derivatives as a Promising Scaffold in Drug Discovery

Numerous purine-containing compounds have undergone extensive investigation for their medical efficacy across various diseases. The swift progress in purine-based medicinal chemistry has brought to light the therapeutic capabilities of purine-derived compounds in addressing challenging medical conditions. Defined by a heterocyclic ring comprising a pyrimidine ring linked with an imidazole ring, purine exhibits a diverse array of therapeutic attributes. This review systematically addresses the multifaceted potential of purine derivatives in combating various diseases, including their roles as anticancer agents, antiviral compounds (anti-herpes, anti-HIV, and anti-influenzae), autoimmune and anti-inflammatory agents, antihyperuricemic and anti-gout solutions, antimicrobial agents, antitubercular compounds, anti-leishmanial agents, and anticonvulsants. Emphasis is placed on the remarkable progress made in developing purine-based compounds, elucidating their significant target sites. The article provides a comprehensive exploration of developments in both natural and synthetic purines, offering insights into their role in managing a diverse range of illnesses. Additionally, the discussion delves into the structure-activity relationships and biological activities of the most promising purine molecules. The intriguing capabilities revealed by these purine-based scaffolds unequivocally position them at the forefront of drug candidate development. As such, this review holds potential significance for researchers actively involved in synthesizing purine-based drug candidates, providing a roadmap for the continued advancement of this promising field.

Design, Synthesis, In Silico Studies and Inhibitory Activity towards Bcr-Abl, BTK and FLT3-ITD of New 2,6,9-Trisubstituted Purine Derivatives as Potential Agents for the Treatment of Leukaemia

We report 31 new compounds designed, synthesized and evaluated on Bcr-Abl, BTK and FLT3-ITD as part of our program to develop 2,6,9-trisubstituted purine derivatives as inhibitors of oncogenic kinases. The design was inspired by the chemical structures of well-known kinase inhibitors and our previously developed purine derivatives. The synthesis of these purines was simple and used a microwave reactor for the final step. Kinase assays showed three inhibitors with high selectivity for each protein that were identified: 4f (IC₅₀ = 70 nM for Bcr-Abl), 5j (IC₅₀ = 0.41 μM for BTK) and 5b (IC₅₀ = 0.38 μM for FLT-ITD). The 3D-QSAR analysis and molecular docking studies suggested that two fragments are potent and selective inhibitors of these three kinases: a substitution at the 6-phenylamino ring and the length and volume of the alkyl group at N-9. The N-7 and the N-methyl-piperazine moiety linked to the aminophenyl ring at C-2 are also requirements for obtaining the activity. Furthermore, most of these purine derivatives were shown to have a significant inhibitory effect in vitro on the proliferation of leukaemia and lymphoma cells (HL60, MV4-11, CEM, K562 and Ramos) at low concentrations. Finally, we show that the selected purines (4i, 5b and 5j) inhibit the downstream signalling of the respective kinases in cell models. Thus, this study provides new evidence regarding how certain chemical modifications of purine ring substituents provide novel inhibitors of target kinases as potential anti-leukaemia drugs.

Trends in Grade 5 Toxicity and Response in Phase I Trials in Hematologic Malignancy: 20-Year Experience From the Cancer Therapy Evaluation Program at the National Cancer Institute

PURPOSE

Cancer drug development has largely shifted from cytotoxic chemotherapy to targeted treatment in the past two decades. Although previous studies have highlighted improvement in response rates in recent phase I trials, disease-focused reporting is limited.

METHODS

We integrated patient-level data for patients with hematologic malignancies who participated in phase I trials sponsored by the National Cancer Institute Cancer Therapy Evaluation Program between January 2000 and May 2019 and estimated the trend of grade 5 toxicity and response by disease subtype over time.

RESULTS

We analyzed 161 trials involving 3,308 patients, all of whom were assessed for toxicity and 2,404 of whom were evaluable for response to therapy. The overall rate of grade 5 toxicities was 1.81% (95% CI, 1.36 to 2.27), with no significant change in the rate over time. Baseline characteristics associated with higher risk of grade 5 toxicity were age and performance status ≥ 2 at enrollment. Overall response rate (ORR) and complete response (CR) rate for all trials during the study period were 25.1% and 14.7%, respectively. A significant increase in both ORR and CR rate was observed over time (ORR: 18.5% in 2000-2005, 25.9% in 2006-2012, and 50.6% in 2013-2019, P < .001). ORR in phase I trials varied across disease subtypes: 20.2% in acute myeloid leukemia, 9.1% in myelodysplastic syndrome, 43.2% in lymphoma, 42.9% in chronic lymphocytic leukemia, 15.1% in acute lymphoblastic leukemia, and 16.5% in myeloma.

CONCLUSION

Over time, the ORR and CR rates in phase I trials for hematologic malignancy have improved meaningfully, whereas the rate of toxicity-related death remains stable. This study provides broad experience that physicians can use when discussing the potential outcomes for patients with hematologic malignancy considering participation in phase I trials.

Epidemiology of acute myeloid leukemia: Recent progress and enduring challenges

Acute myeloid leukemia (AML) is a malignant disorder of the bone marrow which is characterized by the clonal expansion and differentiation arrest of myeloid progenitor cells. The age-adjusted incidence of AML is 4.3 per 100,000 annually in the United States (US). Incidence increases with age with a median age at diagnosis of 68 years in the US. The etiology of AML is heterogeneous. In some patients, prior exposure to therapeutic, occupational or environmental DNA-damaging agents is implicated, but most cases of AML remain without a clear etiology. AML is the most common form of acute leukemia in adults and has the shortest survival (5-year survival = 24%). Curative therapies, including intensive chemotherapy and allogeneic stem cell transplantation, are generally applicable to a minority of patients who are younger and fit, while most older individuals exhibit poor prognosis and survival. Differences in patient outcomes are influenced by disease characteristics, access to care including active therapies and supportive care, and other factors. After many years without therapeutic advances, several new therapies have been approved and are expected to impact patient outcomes, especially for older patients and those with refractory disease.

Evaluating the Impact of the Addition of Cladribine to Standard Acute Myeloid Leukemia Induction Therapy

BACKGROUND

Treatment for acute myeloid leukemia (AML) has remained relatively unchanged over the past few decades. Although recent drug approvals have provided an increase in the number of treatment options in AML, further optimization of standard induction therapy is still necessary. The most commonly utilized induction options have been well studied, but there is a paucity of literature comparing the combination of idarubicin with cytarabine and cladribine.

OBJECTIVE

To assess the clinical effectiveness of the addition of cladribine to idarubicin and cytarabine (7+3 IA) induction therapy in the treatment of AML.

METHODS

This retrospective, propensity score-matched cohort study evaluated 37 patients with previously untreated AML who received either 7+3 IA or idarubicin, cytarabine, and cladribine (7+3+5 IAC) as induction therapy. The primary end point of this study was complete response (CR), with secondary end points including hospital length of stay (LOS), and adverse event rates.

RESULTS

After propensity score matching, odds of reaching CR in the 7+3+5 IAC cohort were increased by 33% (95% CI = 1.09-1.55; P < 0.01) compared with the 7+3 IA cohort. Patients who received cladribine were also found to have a reduction in hospital LOS by 3.5 days (95% CI = 0.07-6.85; P = 0.045) without an increase in adverse event rates.

CONCLUSION

The addition of cladribine to the 7+3 IA regimen may improve clinical outcomes when used as initial induction therapy, without increasing the incidence of adverse event rates.

Invasive aspergillosis in acute myeloid leukemia: Are we making progress in reducing mortality?

The incidence of invasive fungal disease (IFD) has varied during the last decades. However, over the years, we have observed a progressive reduction of mortality, mainly due to wider use of prophylactic antifungal therapy (i.e., new azoles, such as posaconazole), the development of new and more effective antifungal drugs (lipid compounds of amphotericin B, candins, and azoles of the previous generation) and improvement of diagnostic tools. Based on a number of international studies across three decades, the attributable mortality rate for IFD and invasive aspergillosis (IA) among patients with acute myeloid leukemia (AML) has progressively declined. In the first report, in 2001, the attributable mortality rate for aspergillosis observed in AML patients by the GIMEMA (Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto) group was near 60%. A subsequent multicenter Italian study by SEIFEM (Sorveglianza Epidemiologica Infezioni Fungine nelle Emopatie Maligne) reported an attributable mortality of 38% among 3,012 patients recruited from 1999 through 2003. Further reduction to 27% was reported for patients diagnosed between 2004 and 2007 in another SEIFEM study. Over the last few years, a different trend in mortality for IA has been observed in the various phases of therapy in patients with acute leukemia: while in the induction phase of treatment, characterized by a higher incidence of IA, we observed a reduction of mortality over the years, among relapsed/refractory patients, the mortality remains dramatically high.