Purine Nucleoside Analogues Research Articles

Pooled safety summary for patients treated with the CD22-directed cytotoxin moxetumomab pasudotox-tdfk.

7014 Background: Moxetumomab pasudotox-tdfk was FDA-approved in 2018 for the treatment of adults with relapsed/refractory hairy cell leukemia (HCL) who have received ≥2 prior therapies, including a purine nucleoside analog. Methods: The pooled integrated safety summary included all adult patients (N=165) treated with ≥1 dose of moxetumomab across 5 open-label, single-arm clinical trials. Two trials included patients with HCL (N=129, with N=80 in the pivotal phase 3 trial) and 3 trials included patients with non-Hodgkin lymphoma (N=15) or chronic lymphocytic leukemia/small lymphocytic lymphoma (N=21). Overall, 81% were male, median age was 60 years (range 34–84) and 94% had an ECOG ≤1. Results: The most common adverse events (AEs) with moxetumomab were peripheral edema (41%), hypoalbuminemia (35%), and nausea (35%). Serious AEs occurred in 47 (28.5%) patients and were considered treatment-related in 21 (12.7%) patients. Treatment-related AEs were mainly grade 1/2; the most common were peripheral edema (32%), hypoalbuminemia (32%), increased ALT (29%), increased AST (28%), nausea (26%), headache (24%), pyrexia (23%), fatigue (22%), and myalgia (20%). In total, 19 deaths (11.5% of patients) occurred (including 3 in the pivotal trial), with most (13) due to underlying disease and 6 due to AEs (none were assessed as treatment-related by the investigators, however, 1 fatal AE in a non-HCL patient was re-assessed by the Sponsor as possibly related to moxetumomab). In 16 patients (9.7%), a treatment-related AE led to treatment discontinuation, with hemolytic uremic syndrome HUS; 3.6%) and capillary leak syndrome (CLS; 2.4%) the most common. Treatment-related AEs resulted in dose delay, omission or treatment interruption in 11 patients (6.7%). Conclusions: Moxetumomab had an acceptable safety profile based on pooled data from 165 adult patients with hematologic malignancies, with few treatment-related discontinuations. Proactive monitoring of patients is important to manage AEs. These results are consistent with results from the pivotal phase 3 trial in patients with HCL. Clinical trial information: NCT01829711, NCT00586924, NCT00587457, NCT00587015, NCT01030536.

Assessment of microRNA expression in leukemic cells as predictors of sensitivity to purine nucleoside analogs, fludarabine and cladribine, in chronic lymphocytic leukemia patients.

Background: Great progress has been achieved lately in the therapy for chronic lymphocytic leukemia (CLL), one of the most frequently diagnosed adult leukemias. New classes of drugs, such as kinase inhibitors and BCL-2 protein antagonists, have been approved for treatment of CLL patients. Despite the abovementioned therapies the disease can still be effectively treated with purine nucleoside analogs (PNA). However, some patients, for example, those with TP53 gene abnormalities, become resistant, and the other factors involved in the therapy resistance are still being investigated. This study was aimed at analyzing the possible role of microRNAs as markers predicting the outcome of chemotherapy based on PNA – fludarabine and cladribine in CLL patients.Methods: The expression of miR-21, miR-34a, miR-181a and miR-221 in previously separated leukemic cells was assessed with the use of qRQ-PCR technique at the moment of diagnosis in 40 CLL patients. In turn, apoptosis induced by fludarabine and cladribine in 24-hour cell culture was evaluated by determining the increase in the percentage of apoptotic cells of CD5+/CD19+/Cas3+ phenotype, using a flow cytometry method. Nine of the 40 studied subjects were treated with fludarabine-based regimens and were analyzed with regards to in vivo response to PNA.Results: We detected a significantly higher PNA-induced apoptosis rate in patients with high miR-34a expression in comparison to low expression ones. Interestingly, such differences were detected particularly in standard cytogenetic patients.Conclusions: These results may prove an important role of miR-34a expression as a predictor of apoptosis, even in cases when other risk factors like cytogenetic abnormalities are absent. An assessment of microRNAs expression seems to be useful as an indicator of sensitivity to PNA and may help to predict PNA-based therapy outcome.

HSR19-086: Healthcare Costs and Resource Utilization Associated With Adverse Events Among Hairy Cell Leukemia Patients Treated With Purine Nucleoside Analogs

Background: Purine nucleoside analogs (PNAs) are highly effective for first-line treatment of hairy cell leukemia (HCL). In clinical trials of single PNAs, several adverse events (AEs) were reported; however, little is known regarding the costs and healthcare resource utilization (HRU) resulting from AEs in HCL patients (pts) treated with PNAs in non-clinical trial settings. Objective: Determine the costs and HRU of high incident and clinically important AEs associated with PNA therapy in HCL pts in the Truven MarketScan database. Methods: Adults (aged ≥18 years) with ≥2 HCL diagnosis codes ≥30 days apart during January 1, 2006–December 31, 2015 were included. Pts had ≥1 prescription claim for a PNA (cladribine or pentostatin ± rituximab) after HCL diagnosis date. First PNA claim date was defined as the index date. Pts had continuous health plan enrollment for ≥6 months at baseline and ≥12-months follow-up with no PNA in the baseline period. Pts were placed into cohorts based on the occurrence of myelosuppression (MSPN) and opportunistic infections (OI) as these were highest incident and clinically important AEs observed. Generalized linear models were used to compare outcomes during the 12-month follow-up. Results: Of the 219 pts with no history of MSPN, 101 developed MSPN (incidence [I]: 461 per 1000 pt-years) and of 619 pts with no history of OI, 26 developed OI (I: 42 per 1000 pt-years). Demographics were similar between pts with and without MSPN and OI. Pts who developed OI or MSPN had significantly higher inpatient admissions and costs (Table 1). Conclusions: PNA-treated HCL pts who developed MSPN or OI incurred higher HRU than those who did not develop either condition. This indicates the need for new therapeutic strategies to reduce HCL-treatment-associated toxicities.

Lead optimization and biological evaluation of fragment-based cN-II inhibitors

The development of cytosolic 5′-nucleotidase II (cN-II) inhibitors is essential to validate cN-II as a potential target for the reversion of resistance to cytotoxic nucleoside analogues. We previously reported a fragment-based approach combined with molecular modelling, herein, the selected hit-fragments were used again in another computational approach based on the Ilib-diverse (a software enabling to build virtual molecule libraries through fragment based de novo design) program to generate a focused library of potential inhibitors. A molecular scaffold related to a previously identified compound was selected and led to a novel series of compounds. Ten out of nineteen derivatives showed 50–75% inhibition on the purified recombinant protein at 200 μM and among them three derivatives (12, 13 and 18) exhibited Ki in the sub-millimolar range (0.84, 2.4 and 0.58 mM, respectively). Despite their only modest potency, the cN-II inhibitors showed synergistic effects when used in combination with cytotoxic purine nucleoside analogues on cancer cells. Therefore, these derivatives represent a family of non-nucleos(t)idic cN-II inhibitors with potential usefulness to overcome cancer drug resistance especially in hematological malignancies in which cN-II activity has been described as an important parameter.

Dynamic Kinetic Resolution of α-Purine Substituted Alkanoic Acids: Access to Chiral Acyclic Purine Nucleosides.

An efficient route to construct chiral acyclic purine nucleoside analogues via dynamic kinetic resolution of α-purine substituted alkanoic acids is reported. Using ( S)-BTM as the catalyst, diverse chiral acyclic purine nucleoside analogues were obtained in moderate to good yields (up to 93%) and high enantioselectivities (up to 98% ee). Chiral acyclic purine nucleosides could be obtained from the esterified products via reduction reaction, which could then be transferred into Tenofovir analogues.

Adverse Events Among Patients with Hairy Cell Leukemia Treated with Purine Nucleoside Analogs in the United States

Introduction: Purine nucleoside analogs (PNAs) are the recommended first-line treatment in patients with hairy cell leukemia (HCL) owing to their efficacy. However, because of the rarity of this disease, little is known about clinically significant adverse events (AEs) outside of previously performed clinical trials. This retrospective claims-based study of patients treated in the current era of improved supportive care assessed the incidence and prevalence rates of AEs associated with PNA use and healthcare resource utilization (HRU) among patients with HCL enrolled in the Truven MarketScan Commercial Claims and Encounters and the Medicare Supplemental databases.Methods: Adults (≥18 years old) diagnosed with HCL (≥2 medical claims ≥30 days apart) between January 1, 2006 and December 31, 2015 were included in the study. All patients had ≥1 claim for PNA therapy (cladribine or pentostatin ± rituximab) after the HCL diagnosis date and the 1st prescription claim was defined as the index date. Continuous health plan enrollment for ≥6 months pre- (baseline period) and ≥12 months post-index date (follow-up period) was required. Patients treated with a PNA during the baseline period were excluded. Incidence rate was defined as the number of new cases of an AE during the follow-up period divided by the number of patients at risk (patients without any evidence of the adverse event in the 6-month baseline period). Prevalence rate was defined as the number of all AEs (existing cases during the baseline period and new cases during the follow-up period) divided by the total number of patients. Incidence and prevalence rates were calculated as rate per 1000 patient-years at risk. To evaluate the HRU, PNA-treated patients with HCL were categorized based on occurrence of highest AE during the follow-up period. Generalized linear model (GLM) compared HRU during the 12-month follow-up, adjusting for demographic, clinical characteristics, and baseline total healthcare costs.Results: In total, 647 PNA-treated patients with HCL were identified. Mean age (standard deviation) was 57.1 (12.2) years. Most patients were men (81.5%) and resided in the southern USA (32.2%). Over the 12-month follow-up period, 87.2% of the PNA-treated patients developed at least one AE. PNA-related AEs with the highest incidence rate were myelosuppression, anemia, and skin toxicities. The prevalence rate showed a similar trend for PNA-related AEs. Infectious complications including opportunistic infections were seen at a high rate (Table 1). The incidence and prevalence of infectious complications overall were 23.5% and 39.3% (235 and 393 per 1000 patient-years), respectively. Patients who developed myelosuppression had a higher rate of hospitalization compared with those who did not (47.4% vs 12.2%; p<0.0001) and had a longer inpatient length of stay (LOS) (3.4 vs 0.8 [days]; p=0.001). A higher proportion of patients who developed opportunistic infections were hospitalized compared with those who did not (53.7% vs 30.8%; p=0.025) and had a longer inpatient LOS (5.4 vs 2.4 [days]), although this was not statistically significant (p=0.138).Conclusion: This large claims-based dataset of patients with HCL treated with PNAs shows that a substantial proportion of patients developed AEs, including myelosuppression (most frequent) and infectious complications. Because of the nature of the data set, information regarding mortality is not currently available. However, infections due to myelo- and immunosuppression are known to be the most frequent causes of death in this patient population. These findings indicate a need for larger studies evaluating the outcomes of patients with HCL treated with approved therapies to understand better their short- and long-term toxicities, as well as for the development of therapies with lower risks of myelo- and immunosuppression. DisclosuresPavilack:AstraZeneca: Employment. Olufade:AstraZeneca: Equity Ownership; AstraZeneca: Employment. Bashyal:STATinMED: Employment. Li:STATinMED: Employment. Andritsos:HCLF: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy.

Infection at the Time of Initial Therapy for Hairy Cell Leukemia Is Associated with Inferior Time to Next Treatment

Introduction: Hairy Cell Leukemia (HCL) is a rare, chronic hematological malignancy that makes up approximately 2% of all leukemias. HCL patients are at a markedly increased risk for infection related to a combination of disease-related and treatment-related immunosuppression which has been well described in the literature. However, the significance of infection prior to initiation of HCL therapy and its impact on the subsequent selection of HCL treatment, or outcomes, is not well described. Using the HCL patient data registry, we report here the impact of antecedent infection on the treatment patterns and outcomes of HCL patients.Methods: We evaluated adult (≥18 years) patients with HCL who had information regarding antecedent infections and subsequent HCL treatment during 1984-2018. The primary endpoint was progression-free survival (PFS-1). Secondary endpoint included time to next treatment (TTNT). PFS-1 was measured from the date of first HCL treatment to date of progression/death or last follow-up. TTNT was defined as the time from first HCL treatment to initiation of second HCL treatment. The study population was stratified into 3 groups based on the presence or absence of antecedent infections: no infection prior to first HCL treatment (no infection group), infection within 30 days prior to first HCL treatment (infection1 group) and infection >30 days prior to first HCL treatment (infection2 group). Fisher's exact test or Kruskal-Wallis test was used to compare the characteristics among the no infection and infection groups and the Cox proportional hazard model was used to evaluate the association with PFS-1 and TTNT.Results: A total of 205 HCL patients who had information regarding antecedent infections and subsequent HCL treatment were eligible for the study. Among these, 144 (70%) belonged to the no infection group, while 26 patients (13%) belonged to infection1 group and 35 (17%) to infection2 group. Patient characteristics are shown in Table 1 with a breakdown between the three groups. The majority of the patients were Caucasian with a male preponderance and had classic HCL.The patients in the infection1 group had a lower median WBC (K/uL) (1.9 vs 3.1 vs 2.9), particularly the absolute neutrophil count (K/uL) (0.4 vs 0.7 vs 0.8) and significantly lower median hemoglobin (gm%) (10.1 vs 12.2 vs 12.4) relative to the no infection and infection2 groups, respectively (p=0.01). Similarly, a greater proportion of patients in the infection1 group had significant comorbidities (including pulmonary, gastrointestinal and hepatic disease) relative to no infection and infection2 groups as shown in Table 1. The majority of patients received purine nucleoside analogs as their first HCL treatment (no infection group=92%, infection1 group=85%, infection2 group=94%).The median PFS-1 (in years) was better in the no infection group compared to the infection1 group but was not statistically significant (17.0 [95% CI=7.9-not reached (NR)] vs 8.8 [95% CI=4.2-NR], respectively, p=0.98, Figure 1). However, the median TTNT (in years) was significantly longer for HCL patients with no infection versus the infection1 group (6.3 [95% CI=5.4-7.8] vs 3.6 [95% CI=0.7-NR], respectively, p=0.001, Figure 1). On subgroup analysis, relative to the no infection group, median PFS-1 (in years) was not significantly different in infection1 group treated with Pentostatin (10.7 [95% CI=3.53-NR] vs NR [95% CI=1.38-NR], respectively, p=0.43), however, the median PFS-1 (in years) was shorter in the infection1 group treated with Cladribine (17.0 [95% CI=7.67-NR] vs 4.0 [95% CI=2.00-NR], respectively), although not reaching statistical significance (p=0.09) probably due to small sample size.Conclusion: In this large series of HCL patients who received treatment, we show that the patients who had infections at the time of HCL treatment have a significantly shorter TTNT. The reasons for this are unclear but may indicate that patients were unable to receive treatment in a timely manner because of the infection, or were unable to complete treatment because of complications. The significant difference in hemoglobin between the infection1 and other groups indicates the possibility that these patients had more advanced HCL at the time of diagnosis. These findings indicate the potential long term negative impact of infections in patients who need treatment for HCL and reinforce the need for careful management in this setting. [Display omitted] DisclosuresLozanski:Beckman: Research Funding; Coulter: Research Funding; Stem Line: Research Funding; Genentech: Research Funding; Novartis: Research Funding; BI: Research Funding. Andritsos:HCLF: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy.

Down-Regulation of CD25 Antigen in Hairy Cell Leukemia Patients after Treatment

Background:Hairy Cell Leukemia (HCL) is a rare hematological malignancy, comprising only of 2% of all leukemias, with an estimated 900 new cases diagnosed each year in the United States. HCL displays a characteristic immunophenotypic profile that include pan-B cell markers including CD103, CD11c, and CD25. World Health Organization guidelines defines two forms of HCL, classic HCL (cHCL) and variant HCL (HCLv) as two distinct clinical entities. Patients with cHCL have a distinct immunophenotypic profile on their malignant leukemic cells including CD20+, CD19+, CD11c+, CD25+, CD103+, and CD123+, while the leukemic cells from patients with HCLv show CD11c+, CD20+ and CD19+, while lacking CD25 and CD123 expression. Some patients with cHCL will retain CD25 positivity while demonstrating negativity for other typical markers, herein termed atypical HCL (aHCL). Presence or absence of CD25 is an important determinant in classifying patients into cHCL and HCLv. Although it has previously been reported that CD25 expression may be lost during treatment with the targeted agent vemurafenib, we sought to identify whether this immunophenotypic change occurs following other treatment types, including standard purine nucleoside analog therapy and with targeted BTK inhibition.Methods:Adult patients (≥18 years) with a diagnosis of HCL whom had immunophenotype data collected before and after treatment between 2010 and 2018 were included in the study. Immunophenotype and morphological characteristics of initial and follow-up peripheral blood, bone marrow aspirate, and core biopsy specimens were reviewed and correlated with the treatment received.Results:We evaluated 30 HCL patients who underwent different therapies. All available specimens were reviewed and showed morphologic features characteristic for cHCL (n=26, 86.7%), and aHCL (n=4, 13.3%). The median age at HCL diagnosis was 50 years (44-76 years) with male predominance (76%). Patients with aHCL were treated with ibrutinib (n=2) and pentostatin (n=2). Patients with cHCL were treated with pentostatin (n=12), ibrutinib (n=8), vemurafenib (n=4), dabrafenib (n=1), and cladribine (n=1). Bone marrow analyses showed that all the patients had leukemic B-lymphocyte co-expression of CD19, CD20, CD103, CD11c, CD25, and CD123 prior to treatment. Some patients also had a smaller percentage of lymphocytes lacking CD25 expression along with the CD25 positive lymphocytes. Follow-up bone marrow and peripheral blood analysis showed that almost half (n=14, 46%) of treated patients had a partial or complete loss of CD25 expression regardless of the treatment type. Leukemic cells continued to express other HCL signature markers.Conclusion:Our study indicates that during the course of disease some patients display a loss of CD25 expression after therapy. This phenomenon was observed across different therapies and is not specific to the type of treatment. This is the first study to show treatment-dependent CD25 variability with pentostatin, ibrutinib and dabrafenib. Our results advocate for caution when using CD25 for the differential diagnosis of cHCL versus HCLv in treated patients. Future studies are needed in larger patient cohorts to determine the overall role and utility of CD25 in the diagnosis of cHCL and HCLv. DisclosuresLozanski:Genentech: Research Funding; Stem Line: Research Funding; BI: Research Funding; Novartis: Research Funding; Beckman: Research Funding; Coulter: Research Funding. Andritsos:Astra Zeneca: Consultancy; HCLF: Membership on an entity's Board of Directors or advisory committees.

Moxetumomab Pasudotox: First Global Approval.

Moxetumomab pasudotox-tdfk (LUMOXITI™), an anti CD22 recombinant immunotoxin, has been developed by MedImmune and its parent company AstraZeneca for the treatment of hairy cell leukaemia. The product, discovered at the National Cancer Institute, is an optimised version of immunotoxin CAT-3888. Moxetumomab pasudotox is composed of the Fv fragment of an anti-CD22 monoclonal antibody fused to a 38 kDa fragment of Pseudomonas exotoxin A, PE38. The Fv portion of moxetumomab pasudotox binds to CD22, a cell surface receptor expressed on a variety of malignant B-cells, thereby delivering the toxin moiety PE38 directly to tumour cells. Once internalised, PE38 catalyses the ADP ribosylation of the diphthamide residue in elongation factor-2 (EF-2), resulting in the rapid fall in levels of the anti-apoptotic protein myeloid cell leukaemia 1 (Mcl-1), leading to apoptotic cell death. This article summarizes the milestones in the development of moxetumomab pasudotox leading to this first approval for the treatment of adults with relapsed or refractory hairy cell leukaemia who received at least two prior systemic therapies, including treatment with a purine nucleoside analogue. Development of moxetumomab pasudotox for non-Hodgkin’s lymphoma, chronic lymphocytic leukaemia and precursor cell lymphoblastic leukaemia/lymphoma was discontinued.

Waldenström macroglobulinemia: 2019 update on diagnosis, risk stratification, and management.

Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with immunoglobulin M (IgM) monoclonal protein. Clinical features include anemia, thrombocytopenia, hepatosplenomegaly, lymphadenopathy, and rarely hyperviscosity. Presence of IgM monoclonal protein associated with ≥10% clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis. The L265P mutation in MYD88 is detectable in >90% of patients and is found in the majority of IgM monoclonal gammopathy of undetermined significance patients. Age, hemoglobin level, platelet count, β2 microglobulin, and monoclonal IgM concentrations are characteristics that are predictive of outcomes. Not all patients who fulfill WM criteria require therapy; these patients can be observed until symptoms develop. Rituximab-monotherapy is inferior to regimens that combine it with bendamustine, an alkylating agent, a proteosome inhibitor, or ibrutinib. Purine nucleoside analogs are active but usage is declining for less toxic alternatives. The preferred Mayo Clinic induction is rituximab and bendamustine. Potential for stem cell transplantation should be considered in selected younger patients. Bortezomib, fludarabine, thalidomide, everolimus, ibrutinib, carfilzomib, lenalidomide, and bendamustine have all been shown to have activity in relapsed WM. Given WM's natural history, reduction of therapy toxicity is an important part of treatment selection.

Discovery of Novel 7-Aryl 7-Deazapurine 3'-Deoxy-ribofuranosyl Nucleosides with Potent Activity against Trypanosoma cruzi.

Chagas disease is the leading cause of cardiac-related mortality in Latin American countries where it is endemic. Trypanosoma cruzi, the disease-causing pathogen, is unable to synthesize purines de novo, necessitating salvage of preformed host purines. Therefore, purine and purine-nucleoside analogues might constitute an attractive source for identifying antitrypanosomal hits. In this study, structural elements of two purine-nucleoside analogues (i.e., cordycepin and a recently discovered 7-substituted 7-deazaadenosine) led to the identification of novel nucleoside analogues with potent in vitro activity. The structure-activity relationships of substituents at C-7 were investigated, ultimately leading to the selection of compound 5, with a C-7 para-chlorophenyl group, for in vivo evaluation. This derivative showed complete suppression of T. cruzi Y-strain blood parasitemia when orally administered twice daily for 5 days at 25 mg/kg and was able to protect infected mice from parasite-induced mortality. However, sterile cure by immunosuppression could not be demonstrated.

Evaluation of induction chemotherapies after hypomethylating agent failure in myelodysplastic syndromes and acute myeloid leukemia

AbstractHypomethylating agent (HMA) failure in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) carries a poor prognosis with limited treatment options. Although intensive, remission induction chemotherapy is often used subsequently, in particular to bridge to allogeneic transplantation, it is not clear whether an advantage exists for any particular regimen. Based on an international collaboration, we retrospectively analyzed induction response rate and survival in 366 patients after HMA failure. Patients received 7+3, intermediate- to high-dose cytarabine (IDAC), or purine nucleoside analog–based regimens. For the MDS cohort (n = 307), the overall response rate (ORR) was 41%; median overall survival (OS) was 10.8 months, and 40% of responding patients bridged to allogeneic stem cell transplant (allo-SCT). For the AML cohort (n = 59), the ORR was 32%, OS 6 months, and 42% of responding patients bridged to allo-SCT. Prognostic factors for response in MDS included adverse cytogenetics (odds ratio [OR], 0.46, P = .01), age ≥65 years (OR, 0.47; P < .01), and use of IDAC (OR, 2.91, P = .01). Shorter survival was associated with adverse cytogenetics (hazard ratio [HR], 1.43; P = .06). In the AML cohort, OS was decreased by disease progression at time of HMA failure (HR, 2.66; P = .02) and prolonged with use of an anthracycline-containing regimen (HR, 0.37; P = .01). In conclusion, intensive chemotherapy after HMA failure may be a reasonable treatment option for selected patients as a bridge to allogeneic transplantation and should be considered a potential platform for future investigations.

Synthesis of Chiral Six-Membered Carbocyclic Purine Nucleosides via Organocatalytic Enantioselective [3 + 3] Annulation.

A direct route to chiral six-membered carbocyclic purine nucleoside analogues with three chiral stereocenters, including a chiral tetrasubstituted carbon center, via a highly enantioselective [3 + 3] annulation has been established. With the application of Takemoto's catalyst, various chiral six-membered carbocyclic purine nucleoside analogues were obtained in high yields (up to 89%) with moderate to good diastereoselectivities (up to 90:10 dr) and excellent enantioselectivities (92-98% ee). Furthermore, diverse chiral six-membered carbocyclic purine nucleoside analogues were generated by simple transformations.

CD73 inhibition by purine cytotoxic nucleoside analogue-based diphosphonates

The ecto-5′-nucleotidase CD73 has emerged as an important drug target in oncoimmunology as well as in other diseases. We describe new ADP analogues as CD73 inhibitors based on the replacement of the adenosine moiety, in the reference inhibitor APCP, by purine nucleoside analogues. Compounds were assessed for CD73 inhibition both on purified recombinant protein and on CD73-expressing cancer cells. The clofarabine-containing compound (2) was shown to be more potent than APCP with IC50 values of 0.18 μM (vs. 3.8 μM) on purified protein and 0.24 μM (vs. 23.6 μM) on CD73 expressed on cells. This work gives additional insights into structure-activity relationship of substrate-analogues as CD73 inhibitors.

Moxetumomab pasudotox in relapsed/refractory hairy cell leukemia

This is a pivotal, multicenter, open-label study of moxetumomab pasudotox, a recombinant CD22-targeting immunotoxin, in hairy cell leukemia (HCL), a rare B cell malignancy with high CD22 expression. The study enrolled patients with relapsed/refractory HCL who had ≥2 prior systemic therapies, including ≥1 purine nucleoside analog. Patients received moxetumomab pasudotox 40 µg/kg intravenously on days 1, 3, and 5 every 28 days for ≤6 cycles. Blinded independent central review determined disease response and minimal residual disease (MRD) status. Among 80 patients (79% males; median age, 60.0 years), durable complete response (CR) rate was 30%, CR rate was 41%, and objective response rate (CR and partial response) was 75%; 64 patients (80%) achieved hematologic remission. Among complete responders, 27 (85%) achieved MRD negativity by immunohistochemistry. The most frequent adverse events (AEs) were peripheral edema (39%), nausea (35%), fatigue (34%), and headache (33%). Treatment-related serious AEs of hemolytic uremic syndrome (7.5%) and capillary leak syndrome (5%) were reversible and generally manageable with supportive care and treatment discontinuation (6 patients; 7.5%). Moxetumomab pasudotox treatment achieved a high rate of independently assessed durable response and MRD eradication in heavily pretreated patients with HCL, with acceptable tolerability.

Nucleoside Analogue-Based Supramolecular Nanodrugs Driven by Molecular Recognition for Synergistic Cancer Therapy.

The utilization of nanotechnology for the delivery of a wide range of anticancer drugs has the potential to reduce adverse effects of free drugs and improve the anticancer efficacy. However, carrier materials and/or chemical modifications associated with drug delivery make it difficult for nanodrugs to achieve clinical translation and final Food and Drug Administration (FDA) approvals. We have discovered a molecular recognition strategy to directly assemble two FDA-approved small-molecule hydrophobic and hydrophilic anticancer drugs into well-defined, stable nanostructures with high and quantitative drug loading. Molecular dynamics simulations demonstrate that purine nucleoside analogue clofarabine and folate analogue raltitrexed can self-assemble into stable nanoparticles through molecular recognition. In vitro studies exemplify how the clofarabine:raltitrexed nanoparticles could greatly improve synergistic combination effects by arresting more G1 phase of the cell cycle and reducing intracellular deoxynucleotide pools. More importantly, the nanodrugs increase the blood retention half-life of the free drugs, improve accumulation of drugs in tumor sites, and promote the synergistic tumor suppression property in vivo.

Nucleoside analogs to manage sequence divergence in nucleic acid amplification and SNP detection.

Described here are the synthesis, enzymology and some applications of a purine nucleoside analog (H) designed to have two tautomeric forms, one complementary to thymidine (T), the other complementary to cytidine (C). The performance of H is compared by various metrics to performances of other ‘biversal’ analogs that similarly rely on tautomerism to complement both pyrimidines. These include (i) the thermodynamic stability of duplexes that pair these biversals with various standard nucleotides, (ii) the ability of the biversals to support polymerase chain reaction (PCR), (iii) the ability of primers containing biversals to equally amplify targets having polymorphisms in the primer binding site, and (iv) the ability of ligation-based assays to exploit the biversals to detect medically relevant single nucleotide polymorphisms (SNPs) in sequences flanked by medically irrelevant polymorphisms. One advantage of H over the widely used inosine ‘universal base’ and ‘mixed sequence’ probes is seen in ligation-based assays to detect SNPs. The need to detect medically relevant SNPs within ambiguous sequences is especially important when probing RNA viruses, which rapidly mutate to create drug resistance, but also suffer neutral drift, the second obstructing simple methods to detect the first. Thus, H is being developed to detect variants of viruses that are rapidly mutating.

Asymmetric Synthesis of Chiral Acyclic Purine Nucleosides Containing a Hemiaminal Ester Moiety via Three-Component Dynamic Kinetic Resolution.

An efficient route to construct chiral acyclic purine nucleosides containing a hemiaminal ester moiety is reported via three-component dynamic kinetic resolution of purines, aldehydes, and acid anhydrides. The procedure provides diverse chiral acyclic purine nucleoside analogues in a regioselective manner with good yields (up to 93% yield) and excellent enantioselectivities (up to 95% ee). Furthermore, the chiral (acyloxyalkyl)-5-fluorouracil could also be generated as a potential prodrug of 5-fluorouracil.

Raman spectroscopy and density functional theory study of energetically closely separated C2′‐endo and C3′‐endo pentose forms in purine nucleoside analogue drug‐gold conjugates

AbstractWe performed a vibrational analysis of a cyclin‐dependent kinase inhibitor as an anticancer drug using Raman spectroscopy and quantum mechanical calculations. BMK‐Y101, a purine nucleoside analogue cyclin‐dependent kinase inhibitor, was found to adsorb on gold nanoparticles as evidenced by ultraviolet–visible absorption spectroscopy. Density functional theory (DFT) calculations were introduced to examine the energetic stabilities of the tautomeric amino and imino purine rings as well as C3′‐endo and C2′‐endo pentose forms for the possible binding geometries to 6‐atom gold clusters. DFT calculations predicted that the N9 binding mode of the C2′‐endo amino purine conformer would be the most stable in coordination with the gold atoms, despite very small energy differences of 0.026 kcal/mol to the second stable conformer of the N1 coordinated state. Surface‐enhanced Raman scattering (SERS) spectra were analyzed with appropriate vibrational assignments according to the DFT calculations and potential energy distribution analysis. The vibrational band at ~1,460 cm−1, which can be ascribed to the ν(N9–C4)(20%) + ν(N3–C4)(13%) + ν(C10–C7)(12%) + ν(C7–C8)(12%) + ν(N3–C2)(11%) mode for the N9‐coordination on Au6, appeared to be the most prominent in the SERS spectra, as predicted from the DFT calculations. BMK‐Y101 appeared to be detached from gold nanoparticles efficiently not in cell culture media but in hepatocarcinoma cells. Our findings indicate that quantum mechanical DFT calculations can be successfully implemented to interpret the SERS spectral features of the nucleoside drug on Au surfaces.

When nucleoside chemistry met hypervalent iodine reagents.

There has been increasing use of hypervalent iodine reagents in the field of nucleoside chemistry. Applications span: (a) synthesis of nucleoside analogues with sulfur and seleno sugar surrogates, (b) synthesis of unusual carbocyclic and ether ring-containing nucleosides, (c) introduction of sulfur and selenium into pyrimidine bases of nucleosides and analogues, (d) synthesis of isoxazole and isoxazoline ring-containing nucleoside analogues, (e) involvement of purine ring nitrogen atoms for remote C-H bond oxidation, and (f) metal-catalyzed and uncatalyzed synthesis of benzimidazolyl purine nucleoside analogues by intramolecular C-N bond formation. This review offers a perspective on developments involving the use of hypervalent iodine reagents in the field of nucleoside chemistry that have appeared in the literature in the 2003-2017 time frame.