The nitrosoureas: carmustine (BCNU) and lomustine (CCNU)

First-principles study of a SiC nanosheet as an effective material for nitrosourea and carmustine anti-cancer drug delivery

The development of novel nanosheet-based drug delivery systems requires a systematic understanding of the interactions between the drug and the nanosheet carrier under various physiological environments. In this work, we investigated electronic and quantum molecular descriptors of a SiC monolayer adsorbed with the anticancer drugs nitrosourea (NU) and carmustine (BCNU) using density functional theory (DFT). Our calculations revealed negative adsorption energies for both drugs, indicating a spontaneous and energetically favorable adsorption process. Density of states and orbital population analysis studies revealed that both drugs are capable of significantly (>30%) narrowing the gap between HOMO and LUMO, depending on the configuration of the adsorption complex. Furthermore, the electronic and quantum molecular descriptors were investigated in gas and water mediums to explore the effect of the solvent on the adsorption process. Our calculations predict a higher narrowing of the HOMO-LUMO gap in the water phase compared to the gas phase. Besides, a modest reduction in global hardness and a marked increase in the global electrophilicity index were observed after the adsorption of the drug molecules by the SiC nanosheet, indicating its high reactivity towards both NU and BCNU. Changing the medium to water showed a maximum 2× increase in the global electrophilicity index of the nanosheet for NU and a maximum 7× increase for BCNU. Additionally, the thermodynamic study of the adsorption process indicates that the formation energies at high temperatures are smaller than those at low temperatures, unfolding the potential of SiC nanosheet for application in the phototherapy of these drugs.

Chemotherapy for the treatment of intracranial glioma in dogs

Gliomas are the second most common primary brain tumor in dogs and although they are associated with a poor prognosis, limited data are available relating to the efficacy of standard therapeutic options such as surgery, radiation and chemotherapy. Additionally, canine glioma is gaining relevance as a naturally occurring animal model that recapitulates human disease with fidelity. There is an intense comparative research drive to test new therapeutic approaches in dogs and assess if results translate efficiently into human clinical trials to improve the poor outcomes associated with the current standard-of-care. However, the paucity of data and controversy around most appropriate treatment for intracranial gliomas in dogs make comparisons among modalities troublesome. To further inform therapeutic decision-making, client discussion, and future studies evaluating treatment responses, the outcomes of 127 dogs with intracranial glioma, either presumed (n = 49) or histologically confirmed (n = 78), that received chemotherapy as leading or adjuvant treatment are reviewed here. This review highlights the status of current chemotherapeutic approaches to intracranial gliomas in dogs, most notably temozolomide and lomustine; areas of novel treatment currently in development, and difficulties to consensuate and compare different study observations. Finally, suggestions are made to facilitate evidence-based research in the field of canine glioma therapeutics.

Diagnosis and management of complications from the treatment of primary central nervous system tumors in adults

Central nervous system (CNS) tumor patients commonly undergo multimodality treatment in the course of their disease. Adverse effects and complications from these interventions have not been systematically studied, but pose significant challenges in clinical practice and impact function and quality of life, especially in the management of long-term brain tumor survivors. Here, the European Association of Neuro-Oncology (EANO) has developed recommendations to prevent, diagnose, and manage adverse effects and complications in the adult primary brain CNS tumor (except lymphomas) patient population with a specific focus on surgery, radiotherapy, and pharmacotherapy. Specifically, we also provide recommendations for dose adaptations, interruptions, and reexposure for pharmacotherapy that may serve as a reference for the management of standard of care in clinical trials. We also summarize which interventions are unnecessary, inactive or contraindicated. This consensus paper should serve as a reference for the conduct of standard therapy within and outside of clinical trials.

Pharmacokinetics and Biodistribution of 89Zr-Miltuximab and Its Antibody Fragments as Glypican-1 Targeting Immuno-PET Agents in Glioblastoma

Glioblastoma (GBM) is the most aggressive form of primary brain cancer, accounting for about 85% of all primary central nervous system (CNS) tumors. With standard treatment strategies like surgery, radiation, and chemotherapy, the median survival time of patients with GBM is only 12-15 months from diagnosis. The poor prognosis of GBM is due to a very high tumor recurrence rate following initial treatment, indicating a dire need for improved diagnostic and therapeutic alternatives for this disease. Antibody-based immunotheranostics holds great promise in treating GBM, combining the theranostic applications of radioisotopes and target-specificity of antibodies. In this study, we developed and validated antibody-based positron emission tomography (PET) tracers targeting the heparan sulfate proteoglycan, glypican-1 (GPC-1), for noninvasive detection of disease using diagnostic molecular imaging. GPC-1 is overexpressed in multiple solid tumor types, including GBM, and is a promising biomarker for novel immunotheranostics. Here, we investigate zirconium-89 (⁸⁹Zr)-conjugated Miltuximab (a clinical stage anti-GPC-1 monoclonal antibody developed by GlyTherix, Ltd.) and engineered fragments for their potential as immuno-PET tracers to detect GPC-1^positive GBM tumors in preclinical models. We explore the effects of molecular size, avidity, and Fc-domain on the pharmacokinetics and biodistribution in vivo, by comparing in parallel the full-length antibody (Miltuximab), Fab'2, Fab, and single-chain variable fragment (scFv) formats. High radiolabeling efficiency (>95%) was demonstrated by all the formats and the stability post-radiolabeling was higher for larger constructs of Miltuximab and the Fab. Receptor-mediated internalization of all ⁸⁹Zr-labeled formats was observed in a human GBM cell line in vitro, while full-length Miltuximab demonstrated the highest tumor retention (5.7 ± 0.94% ID/g, day-9 postinjection (p.i.)) and overall better tumor-to-background ratios than the smaller Fc-less formats. Results from in vivo PET image quantification and ex vivo scintillation counting were highly correlated. Altogether, ⁸⁹Zr-DFO-Miltuximab appears to be an effective immuno-PET imaging agent for detecting GPC-1^positive tumors such as GBM and the current results support utility of the Fc containing whole mAb format over smaller antibody fragments for this target.

Drug-Drug Interactions of Cannabidiol with Standard-of-Care Chemotherapeutics

Cannabidiol (CBD) is an easily accessible and affordable Marijuana (Cannabis sativa L.) plant derivative with an extensive history of medical use spanning thousands of years. Interest in the therapeutic potential of CBD has increased in recent years, including its anti-tumour properties in various cancer models. In addition to the direct anticancer effects of CBD, preclinical research on numerous cannabinoids, including CBD, has highlighted their potential use in: (i) attenuating chemotherapy-induced adverse effects and (ii) enhancing the efficacy of some anticancer drugs. Therefore, CBD is gaining popularity as a supportive therapy during cancer treatment, often in combination with standard-of-care cancer chemotherapeutics. However, CBD is a biologically active substance that modulates various cellular targets, thereby possibly resulting in unpredictable outcomes, especially in combinations with other medications and therapeutic modalities. In this review, we summarize the current knowledge of CBD interactions with selected anticancer chemotherapeutics, discuss the emerging mechanistic basis for the observed biological effects, and highlight both the potential benefits and risks of such combined treatments. Apart from the experimental and preclinical results, we also indicate the planned or ongoing clinical trials aiming to evaluate the impact of CBD combinations in oncology. The results of these and future trials are essential to provide better guidance for oncologists to judge the benefit-versus-risk ratio of these exciting treatment strategies. We hope that our present overview of this rapidly advancing field of biomedicine will inspire more preclinical and clinical studies to further our understanding of the underlying biology and optimize the benefits for cancer patients.

Continuous Extraction of 2-Chloroethyl isocyanate for 1-(2-chloroethyl)-3-cyclohexylurea Purification

This study details the development of simulation-aided design, development, and successful operation of a continuous liquid-liquid extraction platform made with 1.5 mm tubing for the extraction of 2-chloroethyl isocyanate, an important reagent in the synthesis of cancer drugs. Preliminary solvent screening was carried out with partition coefficient calculations to determine solvents of interest. Next, batch and flow extraction experiments of 2-chloroethyl isocyanate in 2-methyl tetrahydrofuran and water were conducted to estimate extraction parameters. Following parameter estimation, experimental and model values for KLa were determined in the range of 1.13×10-3 to 36.0×10-3 s-1. Simulations of the extraction of 2-chloroethyl isocyanate were found to agree with experimental data resulting in a maximum efficiency of 77% and percent extraction of 69% for the continuous platform. Finally, model selection and discrimination was implemented for design space generation with experimental and model determined KLa values to guide lab-scale operation.

Current and promising treatment strategies in glioma

Gliomas are the most common primary central nervous system tumors; despite recent advances in diagnosis and treatment, glioma patients generally have a poor prognosis. Hence there is a clear need for improved therapeutic options. In recent years, significant effort has been made to investigate immunotherapy and precision oncology approaches. The review covers well-established strategies such as surgery, temozolomide, PCV, and mTOR inhibitors. Furthermore, it summarizes promising therapies: tumor treating fields, immune therapies, tyrosine kinases inhibitors, IDH(Isocitrate dehydrogenase)-targeted approaches, and others. While there are many promising treatment strategies, none fundamentally changed the management of glioma patients. However, we are still awaiting the outcome of ongoing trials, which have the potential to revolutionize the treatment of glioma.

Role of inflammation and oxidative stress in chemotherapy-induced neurotoxicity

Chemotherapeutic agents may adversely affect the nervous system, including the neural precursor cells as well as the white matter. Although the mechanisms are not completely understood, several hypotheses connecting inflammation and oxidative stress with neurotoxicity are now emerging. The proposed mechanisms differ depending on the class of drug. For example, toxicity due to cisplatin occurs due to activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which alters hippocampal long-term potentiation. Free radical injury is also involved in the cisplatin-mediated neurotoxicity as dysregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) has been seen which protects against the free radical injury by regulating glutathione S-transferases and hemeoxygenase-1 (HO-1). Thus, correcting the imbalance between NF-κB and Nrf2/HO-1 pathways may alleviate cisplatin-induced neurotoxicity. With newer agents like bortezomib, peripheral neuropathy occurs due to up-regulation of TNF-α and IL-6 in the sensory neurons. Superoxide dismutase dysregulation is also involved in bortezomib-induced neuropathy. This article reviews the available literature on inflammation and oxidative stress in neurotoxicity caused by various classes of chemotherapeutic agents. It covers the conventional medicines like platinum compounds, vinca alkaloids, and methotrexate, as well as the newer therapeutic agents like immunomodulators and immune checkpoint inhibitors. A better understanding of the pathophysiology will lead to further advancement in strategies for management of chemotherapy-induced neurotoxicity.

Antibody-Based Formats to Target Glioblastoma: Overcoming Barriers to Protein Drug Delivery

Glioblastoma (GB) is recognized as the most aggressive form of primary brain cancer. Despite advances in treatment strategies that include surgery, radiation, and chemotherapy, the median survival time (∼15 months) of patients with GB has not significantly improved. The poor prognosis of GB is also associated with a very high chance of tumor recurrence (∼90%), and current treatment measures have failed to address the complications associated with this disease. However, targeted therapies enabled through antibody engineering have shown promise in countering GB when used in combination with conventional approaches. Here, we discuss the challenges in conventional as well as future GB therapeutics and highlight some of the known advantages of using targeted biologics to overcome these impediments. We also review a broad range of potential alternative routes that could be used clinically to administer anti-GB biologics to the brain through evasion of its natural barriers.

Continuous Flow Synthesis of Anticancer Drugs

Continuous flow chemistry is by now an established and valued synthesis technology regularly exploited in academic and industrial laboratories to bring about the improved preparation of a variety of molecular structures. Benefits such as better heat and mass transfer, improved process control and safety, a small equipment footprint, as well as the ability to integrate in-line analysis and purification tools into telescoped sequences are often cited when comparing flow to analogous batch processes. In this short review, the latest developments regarding the exploitation of continuous flow protocols towards the synthesis of anticancer drugs are evaluated. Our efforts focus predominately on the period of 2016-2021 and highlight key case studies where either the final active pharmaceutical ingredient (API) or its building blocks were produced continuously. It is hoped that this manuscript will serve as a useful synopsis showcasing the impact of continuous flow chemistry towards the generation of important anticancer drugs.

Surface adsorption of nitrosourea on pristine and doped (Al, Ga and In) boron nitride nanosheets as anticancer drug carriers: the DFT and COSMO insights

To minimize the side effects of chemotherapeutic drugs and enhance the effectiveness of cancer treatment, it is necessary to find a suitable drug delivery carrier for anticancer drugs. Recently nanomaterials are extensively being studied as drug vehicles and transport drugs in tumor cells. Using DFT calculations, the adsorption behavior with electronic sensitivity and reactivity of pristine and doped (Al, Ga and In)-BNNS towards the nitrosourea (NU) drug has been investigated in gas as well as water media. Our calculations showed that the NU drug is physically adsorbed on the pristine BNNS with −0.49 and −0.26 eV by transferring little amount of charge of about 0.033e and 0.046e in gas and water media in the most stable complex. But after replacing one of the central B atoms with an Al or Ga or In atom, the sensitivity of the doped BNNS remarkably enhances towards the NU drug molecules. The NU drug prefers to be chemically adsorbed on the BN(Al)NS, BN(Ga)NS and BN(In)NS by −1.28, −1.58 and −3.06 eV in the gas phase and −1.34, −1.23 and −3.65 eV in water media in the most stable complexes respectively. The large destabilization of LUMO energies after the adsorption of the NU drug on the BN(Al)NS, BN(Ga)NS and BN(In)NS significantly reduces their E_g from 4.37 to 0.69, 4.37 to 1.04 and 4.33 to 0.66 eV in the S1 complex respectively. The reduction of E_g of doped BNNS by the NU drug greatly enhances the electrical conductivity which can be converted to an electrical signal. Therefore, this doped BNNS can be used as a fascinating electronic sensor for the detection of NU drug molecules. Furthermore the work function of the doped BNNS was largely affected by the NU drug adsorption about 47.3%, 39.3% and 40.4% in the gas phase and 41.3%, 36.6% and 31.6% in water media in the S1 complex of NU/BN(Al)NS, NU/BN(Ga)NS and NU/BN(In)NS respectively. Thus, the doped BNNS may be used as a Ф type sensor for NU drug molecules.

Doped (Al, Ga and In)-BNNS can be used as fascinating drug carriers for the NU drug.

Retinal toxicities of systemic anticancer drugs

Newer anticancer drugs have revolutionized cancer treatment in the last decade, but conventional chemotherapy still occupies a central position in many cancers, with combination therapy and newer methods of delivery increasing their efficacy while minimizing toxicities. We discuss the retinal toxicities of anticancer drugs with an emphasis on the mechanism of toxicity. Uveitis is seen with the use of v-raf murine sarcoma viral oncogene homolog B editing anticancer inhibitors as well as immunotherapy. Most of the cases are mild with only anterior uveitis, but severe cases of posterior uveitis, panuveitis, and Vogt-Koyanagi-Harada-like disease may also occur. In the retina, a transient neurosensory detachment is observed in almost all patients on mitogen-activated protein kinase kinase (MEK) inhibitors. Microvasculopathy is often seen with interferon α, but vascular occlusion is a more serious toxicity caused by interferon α and MEK inhibitors. Crystalline retinopathy with or without macular edema may occur with tamoxifen; however, even asymptomatic patients may develop cavitatory spaces seen on optical coherence tomography. A unique macular edema with angiographic silence is characteristic of taxanes. Delayed dark adaptation has been observed with fenretinide. Interestingly, this drug is finding potential application in Stargardt disease and age-related macular degeneration.

Molecular docking of potential cytotoxic alkylating carmustine derivatives 2-chloroethylnitrososulfamides analogues of 2-chloroethylnitrosoureas

The objective of this work was the molecular modelling by bio-isostery of 2-chloroethylnitrosoureas CENU into 2-chloroethylnitrososulfamides CENS derived from Carmustine. We evaluated the pharmacodynamic profile of the new chemical class by studying molecular docking using innovative software. Good molecular docking scores were obtained through Auto-dock vina of the PyRx 0.8 software, the energy of the complexes formed (Target-Ligand) during the interaction varies from - 5,400 to -5,700 Kcal/mol, the total average between the 45 conformers is -5,213 Kcal/mol. The results were validated by Auto-dock vina 1.5.6 in collaboration with the Molecular Chemistry and Natural Substances Laboratory at the Meknes Faculty of Science - Morocco, a range of -4,900 to -5,100 Kcal/mol was noted for CENS complexes derived from Carmustine with the 2DND target, reflecting a better CENS chemical affinity to the biological target and the stability of the ligand-DNA complex, compared with the analogue reference Carmustine with a score of - 4,700 Kcal/mol. By superimposing the results of molecular docking, analysis of data from the study of electrophilia based on load transfer ECT and publications on CENS, we can predict that inter-strand crosslink is likely to occur between the Guanine dG22 of strand B and the Cytosine dC3 of strand A, located in the poly dA-poly dT segment end within the narrow minor groove of the DNA target (2DND). The molecular docking study was a preliminary approach to understand the therapeutic mode of action of CENS.Communicated by Ramaswamy H. Sarma.

The l-Alanosine Gene Cluster Encodes a Pathway for Diazeniumdiolate Biosynthesis

N-Nitroso-containing natural products are bioactive metabolites with antibacterial and anticancer properties. In particular, compounds containing the diazeniumdiolate (N-nitrosohydroxylamine) group display a wide range of bioactivities ranging from cytotoxicity to metal chelation. Despite the importance of this structural motif, knowledge of its biosynthesis is limited. Herein we describe the discovery of a biosynthetic gene cluster in Streptomyces alanosinicus ATCC 15710 responsible for producing the diazeniumdiolate natural product l-alanosine. Gene disruption and stable isotope feeding experiments identified essential biosynthetic genes and revealed the source of the N-nitroso group. Additional biochemical characterization of the biosynthetic enzymes revealed that the non-proteinogenic amino acid l-2,3-diaminopropionic acid (l-Dap) is synthesized and loaded onto a free-standing peptidyl carrier protein (PCP) domain in l-alanosine biosynthesis, which we propose may be a mechanism of handling unstable intermediates generated en route to the diazeniumdiolate. These discoveries will facilitate efforts to determine the biochemistry of diazeniumdiolate formation.

Alkylating anticancer agents and their relations to microRNAs

Alkylating agents represent an important class of anticancer drugs. The occurrence and emergence of tumor resistance to the treatment with alkylating agents denotes a severe problem in the clinics. A detailed understanding of the mechanisms of activity of alkylating drugs is essential in order to overcome drug resistance. In particular, the role of non-coding microRNAs concerning alkylating drug activity and resistance in various cancers is highlighted in this review. Both synthetic and natural alkylating agents, which are approved for cancer therapy, are discussed concerning their interplay with microRNAs.

An N-nitrosating metalloenzyme constructs the pharmacophore of streptozotocin

N-nitroso-containing small molecules, such as the bacterial natural product streptozotocin, are prominent carcinogens^1,2 and important cancer chemotherapeutics^3,4. Despite this functional group’s significant impact on human health, dedicated enzymes involved in N-nitroso assembly have not been identified. Here, we describe a metalloenzyme from streptozotocin biosynthesis (SznF) that catalyzes an oxidative rearrangement of the guanidine group of N^ω-methyl-L-arginine to generate an N-nitrosourea product. Structural characterization and mutagenesis of SznF uncovered two separate active sites that promote distinct steps in this transformation using different iron-containing metallocofactors. The discovery of this biosynthetic reaction, which has little precedent in enzymology or organic synthesis, expands the catalytic capabilities of non-heme iron-dependent enzymes to include N–N bond formation. We find biosynthetic gene clusters encoding SznF homologs are widely distributed among bacteria, including environmental organisms, plant symbionts, and human pathogens, suggesting an unexpectedly diverse and uncharacterized microbial reservoir of bioactive N-nitroso metabolites.

Inventory of oral anticancer agents: Pharmaceutical formulation aspects with focus on the solid dispersion technique

Dissolution from the pharmaceutical formulation is a prerequisite for complete and consistent absorption of any orally administered drug, including anticancer agents (oncolytics). Poor dissolution of an oncolytic can result in low oral bioavailability, high variability in blood concentrations and with that suboptimal or even failing therapy. This review discusses pharmaceutical formulation aspects and absorption pharmacokinetics of currently licensed orally administered oncolytics. In nearly half of orally dosed oncolytics poor dissolution is likely to play a major role in low and unpredictable absorption. Dissolution-limited drug absorption can be improved with a solid dispersion which is a formulation method that induces super-saturated drug dissolution and with that it enhances in vivo absorption. This review discusses formulation principles with focus on the solid dispersion technology and how it works to enhance drug absorption. There are currently three licensed orally dosed oncolytics formulated as a solid dispersion (everolimus, vemurafenib and regorafenib) and these formulations result in remarkably improved dissolution and absorption compared to what can be achieved with conventional formulations of the respective oncolytics. Because of the successful implementation of these three solid dispersion formulations, we encourage the application of this formulation method for poorly soluble oral oncolytics.

Toca 511 plus 5-fluorocytosine in combination with lomustine shows chemotoxic and immunotherapeutic activity with no additive toxicity in rodent glioblastoma models

BACKGROUND

Toca 511, a gamma retroviral replicating vector encoding cytosine deaminase, used in combination with 5-fluorocytosine (5-FC) kills tumor by local production of 5-fluorouracil (5-FU), inducing local and systemic immunotherapeutic response resulting in long-term survival after cessation of 5-FC. Toca 511 and Toca FC (oral extended-release 5-FC) are under investigation in patients with recurrent high-grade glioma. Lomustine is a treatment option for patients with high-grade glioma.

METHODS

We investigated the effects of lomustine combined with Toca 511 + 5-FC in syngeneic orthotopic glioma models. Safety and survival were evaluated in immune-competent rat F98 and mouse Tu-2449 models comparing Toca 511 + 5-FC to lomustine + 5-FC or the combination of Toca 511 + 5-FC + lomustine. After intracranial implantation of tumor, Toca 511 was delivered transcranially followed by cycles of intraperitoneal 5-FC with or without lomustine at the first or fourth cycle.

RESULTS

Coadministration of 5-FC with lomustine was well tolerated. In F98, combination Toca 511 + 5-FC and lomustine increased median survival, but "cures" were not achieved. In Tu-2449, combination Toca 511 + 5-FC and lomustine increased median survival and resulted in high numbers of cure. Rejection of tumor rechallenge occurred after treatment with Toca 511 + 5-FC or combined with lomustine, but not with lomustine + 5-FC. Mixed lymphocyte-tumor cell reactions using splenocytes from cured animals showed robust killing of target cells in an effector:target ratio-dependent manner with Toca 511 + 5-FC and Toca 511 + 5-FC + lomustine day 10.

CONCLUSION

The combination of Toca 511 + 5-FC and lomustine shows promising efficacy with no additive toxicity in murine glioma models. Immunotherapeutic responses resulting in long-term survival were preserved despite lomustine-related myelosuppression.

N6-methyladenine functions as a potential epigenetic mark in eukaryotes

N(6)-methyladenine (6mA) is one of the most abundant types of DNA methylation, and plays an important role in bacteria; however, its roles in higher eukaryotes, such as plants, insects, and mammals, have been considered less important. Recent studies highlight that 6mA does indeed occur, and that it plays an important role in eukaryotes, such as worm, fly, and green algae, and thus the regulation of 6mA has emerged as a novel epigenetic mechanism in higher eukaryotes. Despite this intriguing development, a number of important issues regarding its biological roles are yet to be addressed. In this review, we focus on the 5mC and 6mA modifications in terms of their production, distribution, and the erasure of 6mA in higher eukaryotes including mammals. We perform an analysis of the potential functions of 6mA, hence widening understanding of this new epigenetic mark in higher eukaryotes, and suggesting future studies in this field.

Overexpression of Nrf2 attenuates Carmustine-induced cytotoxicity in U87MG human glioma cells

Background

Malignant glioma is one of the most devastating tumors in adults with poor patient prognosis. Notably, glioma often exhibits resistance to conventional chemotherapeutic approaches, complicating patient treatments. However, the molecular mediators involved in tumor chemoresistance remain poorly defined, creating a barrier to the successful management of glioma. In the present study, we hypothesized that the antioxidant transcription factor, Nrf2 (nuclear factor erythroid-derived 2 like 2), attenuates glioma cytotoxicity to Carmustine (BCNU), a widely used chemotherapeutic agent known to modulate cellular oxidative balance.

Methods

To test the hypothesis, we employed human malignant glioma cell line, U87MG and overexpression of Nrf2 in glioma cells was achieved using both pharmacological and genetic approaches.

Results

Notably, induction of Nrf2 was associated with increased expression of heme oxygenase-1 (HO-1), a stress inducible enzyme involved in anti-oxidant defense. In addition, over expression of Nrf2 in U87MG cells significantly attenuated the cytotoxicity of Carmustine as evidenced by both cellular viability assay and flow cytometry analysis. Consistent with this, antioxidants such as glutathione and N-acetyl cysteine significantly reduced Carmustine mediated glioma cytotoxicity.

Conclusions

Taken together, these data strongly implicate an unexplored role of Nrf2 in glioma resistance to Carmustine and raise the possible use of Nrf2 inhibitors as adjunct to Carmustine for the treatment of malignant glioma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1134-z) contains supplementary material, which is available to authorized users.

Interstitial chemotherapy for malignant glioma: Future prospects in the era of multimodal therapy

The advent of interstitial chemotherapy has significantly increased therapeutic options for patients with malignant glioma. Interstitial chemotherapy can deliver high concentrations of chemotherapeutic agents, directly at the site of the brain tumor while bypassing systemic toxicities. Gliadel, a locally implanted polymer that releases the alkylating agent carmustine, given alone and in combination with various other antitumor and resistance modifying therapies, has significantly increased the median survival for patients with malignant glioma. Convection enhanced delivery, a technique used to directly infuse drugs into brain tissue, has shown promise for the delivery of immunotoxins, monoclonal antibodies, and chemotherapeutic agents. Preclinical studies include delivery of chemotherapeutic and immunomodulating agents by polymer and microchips. Interstitial chemotherapy was shown to maximize local efficacy and is an important strategy for the efficacy of any multimodal approach.

The role of Gliadel wafers in the treatment of high-grade gliomas

Glioblastoma multiforme (GBM) is the most aggressive brain tumor. Standard treatment includes surgery, radiation and chemotherapy. Prognosis is dismal with an average survival of approximately 1 year. Gliadel wafers are one treatment option, working as a source for local chemotherapy delivery. Their use is controversial with questionable survival benefit and potential side effects. We reviewed the literature in an effort to clarify their role in the treatment of high-grade gliomas. A systematic PubMed search was performed using the keywords 'Gliadel', 'carmustine' or 'BCNU wafers' in newly diagnosed high-grade glioma patients. Treatment regimen, and median survival were analyzed. Adverse event ratio was calculated by computing the number of adverse events in a study per patient receiving carmustine wafers. Nineteen studies with 795 patients were included in our review. Survival was 8.7-22.6 months with a mean overall survival (OS) of 16.2 months (control survival is approximately 14 months with surgery and adjuvant chemoradiotherapy). Adverse event ratio using Gliadel wafersin control group. Complication rate was 42.7%. Gliadel wafers may marginally increase survival and local control in newly diagnosed GBM patients but are associated with a high complication rate; therefore, we do not recommend using Gliadel wafers in patients with GBM. Further research may be warranted once a safer alternative to Gliadel wafers has been introduced.

Low apparent risk of CCNU (lomustine)-associated clinical hepatotoxicity in cats

The purpose of this study was to evaluate the prevalence of serum alanine transaminase (ALT) increases in cats treated with 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU, lomustine). The medical records of 95 cats treated with CCNU were reviewed, 29 of which met study criteria (at least one treatment with CCNU as a single agent, and at least one pretreatment and one post-treatment complete biochemical profile). Cats that received concurrent prednisone or dexamethasone were included, but those that received concurrent hepatoprotective or hepatotoxic medications were excluded. Cats included in the study were diagnosed with hepatic carcinoma, mammary carcinoma, lymphoma, mast cell tumor, plasma cell tumor and gastrointestinal leiomyoma. CCNU was given as a single agent at 31-60 mg/m(2), once every 4-8 weeks. Serum alanine transaminase (ALT) activity was measured after at least one dose of CCNU. Four cats (13.7%) had increased ALT activity above the reference interval before starting treatment. Two additional cats (6.8%) developed increased ALT activity above the reference interval 1 month after treatment with CCNU. One cat developed clinical signs potentially associated with hepatotoxicity, without a concurrent increase in ALT, 3 weeks following the final dose of CCNU. No association between dosing frequency, cumulative dose, initial starting dose or concurrent medications, and increases in ALT were found. Clinically significant hepatic injury is seemingly uncommon in cats treated with CCNU.

Quantification of meCCNU-induced dG-dC crosslinks in oligonucleotide duplexes by liquid chromatography/electrospray ionization tandem mass spectrometry

Chloroethynitrosoureas (CENUs) are important alkylating agents widely used in the treatment of cancers. Decomposition of CENUs generates active electrophilic ions that damage DNA, including the formation of dG-dC crosslinks which represents the most important cytotoxic mechanism of CENUs. In this work, a high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method was employed to analyze the dG-dC crosslinks induced by 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (meCCNU, Semustine). The direct quantitation of dG-dC crosslinks in oligonucleotide duplexes was achieved by the selected reaction monitoring (SRM) mode using synthesized (15) N(3) -labeled dG-dC as an internal standard. Methods of enzymatic digestion and HPLC separation were developed for obtaining separation and reproducibility of the dG-dC peak in chromatograms. The limit-of-detection (LOD) was determined to be 0.08 nM and the limit-of-quantification (LOQ) was determined to be 0.16 nM. The linearity of the calibration curve was 0.9997 over the range of 0.08 to 32 nM. The precision and accuracy of the method ranged from 1.1 to 6.6% and 96 to 109%, respectively. The recovery of the dG-dC crosslink in the enzymatic hydrolysates from the oligonucleotide duplex was determined to be from 91 to 106%. The results of the validation study indicate that the method is suitable for quantifying dG-dC crosslinks in DNA. Consequently, this method was used to determine meCCNU-induced dG-dC crosslinks in four duplexes with different GC contents. The results showed that the crosslinking fraction (CF) increased as the GC content in the duplex increased, and a relatively low CF was observed in the early period of the reaction.

CCNU (lomustine) toxicity in dogs: a retrospective study (2002-07)

OBJECTIVE

To describe the incidence of haematological, renal, hepatic and gastrointestinal toxicities in tumour-bearing dogs receiving 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU).

DESIGN

The medical records of 206 dogs that were treated with CCNU at the Melbourne Veterinary Specialist Centre between February 2002 and December 2007 were retrospectively evaluated.

RESULTS

Of the 206 dogs treated with CCNU, 185 met the inclusion criteria for at least one class of toxicity. CCNU was used most commonly in the treatment of lymphoma, mast cell tumour, brain tumour, histiocytic tumours and epitheliotropic lymphoma. Throughout treatment, 56.9% of dogs experienced neutropenia, 34.2% experienced anaemia and 14.2% experienced thrombocytopenia. Gastrointestinal toxicosis was detected in 37.8% of dogs, the most common sign of which was vomiting (24.3%). Potential renal toxicity and elevated alanine transaminase (ALT) concentration were reported in 12.2% and 48.8% of dogs, respectively. The incidence of hepatic failure was 1.2%.

CONCLUSIONS

CCNU-associated toxicity in dogs is common, but is usually not life threatening.

Proline analogue of nitrosourea as a new cytotoxic prodrug

Carmustine is frequently used as anticancer drug. High toxicity and low selectivity reduces the application of this drug. Though, there is a necessity to find new compounds characterized by similar therapeutic effects but a higher selectivity and safety. As a result, the proline analogue of nitrosourea, N-[N'-(2-bromophenyl)-N'-nitrosocarbamoyl]proline (AC), has been synthesized. The aim of this study was to compare the influence of carmustine and the proline analogue of nitrosourea on the antioxidant abilities of fibroblasts and leukemia cells, MOLT4. It was shown that carmustine as well as AC cause an increase in hydrogen peroxide concentration in normal and neoplastic cells. Incubation with both compounds led to a diminution of the activity of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, and reductase. Changes in activity / level of antioxidant parameters were accompanied by augmentation of lipid and oxidative protein modifications. In conclusion, carmustine and AC cause changes in the antioxidative system of normal and MOLT4 cells and are a reason of oxidative stress formation.

Medulloblastoma in childhood: revisiting intrathecal therapy in infants and children

INTRODUCTION

Intrathecal chemotherapy is being explored in medulloblastoma in pre-school children as part of brain-sparing strategies and as an alternative to unacceptably neurotoxic cranio-spinal radiotherapy. The range of drugs suitable for this route of administration is restricted by the lack of research evidence of pharmacological suitability and efficacy of other drugs in medulloblastoma.

METHODS

Ideal clinical, biological, physicochemical and pharmaceutical properties for intrathecal administration were defined through literature review of pharmaceutical texts, Medline, Embase and consulting the manufacturers. A total of 126 chemotherapy agents were assessed against these criteria by searching the academic domain of pharmaceutical texts, computer databases and consultation with manufacturers.

RESULTS

Of the 126 candidate drugs, 99 were rejected because of documentation of their irritant nature, neurotoxicity and requirement for hepatic activation in standard pharmaceutical texts. Fifty were rejected for a single identifiable reason including, neurotoxicity (n = 24), irritant (n = 15), needs enzyme activation (n = 5), clinical evidence of intrathecal neurotoxicity (n = 4) and no evidence of tumour-specific efficacy (n = 2). Where two reasons were cited the justifications were: neurotoxic and irritant (n = 3) and needs activation and systemic administration results in equivalent concentration (n = 1). Twenty-seven drugs remained of which 12 were selected as eligible for further clinical investigation, and 15 were selected for further pre-clinical investigation.

CONCLUSIONS

The pre-determined criteria were not applicable, in their entirety, in the majority of drugs, due to lack of information in the academic domain, emphasising the importance of a more open approach for sharing basic drug information. The prioritised list of 12 candidate drugs for clinical trial and 15 for pre-clinical investigation justify that a concerted research effort in this area of practice is made.

Use of lomustine to treat cutaneous nonepitheliotropic lymphoma in a cat

A 17-year-old spayed female domestic shorthair cat was referred for evaluation of severe skin lesions, including ulceration, nodule formation, erythema, and alopecia. Cutaneous nonepitheliotropic lymphoma was diagnosed histologically. There was no evidence of visceral organ involvement, but renal function was decreased. The cat was treated with lomustine (45.5 mg/m2, PO, q 21 d), and skin lesions resolved after administration of the third dose. No severe toxicoses were identified. Results suggest that lomustine may be useful for treatment of cutaneous nonepitheliotropic lymphoma in cats; however, optimal dosage, efficacy, and potential adverse effects must be determined.

Carmustine, Vincristine, and Prednisone in the Treatment of Canine Lymphosarcoma

A chemotherapeutic protocol using carmustine in combination with vincristine and prednisone was tested in dogs with multicentric malignant lymphosarcoma. Of seven dogs treated, six (85.7%) achieved complete remission. A partial response occurred in one dog. Median survival time was 224 days (mean 386 days), and median duration of remission was 183 days (mean 323 days). Marked neutropenia was observed following carmustine administration. There were no significant alterations in platelets and red blood cell counts during treatment, and no abnormalities attributable to the chemotherapy were found in serum biochemical profiles. Results of this study showed that carmustine is an effective alternative option in the treatment of canine lymphosarcoma.

New chemotherapy agents in veterinary medicine

Several anticancer drugs have been added to the therapeutic armamentarium in recent years. Some of these agents are traditional drugs with a long history of use in human oncology. Increased sophistication in clinical trial design in veterinary oncology has allowed the incorporation of agents previously viewed as excessively toxic. Other agents have been developed more recently. This article summarizes the veterinary experience with two older alkylating agents, lomustine and streptozocin, and newer compounds ifosfamide and gemcitabine. The published literature regarding veterinary use of these agents is limited, and the reader is advised to contact a veterinary oncologist for current guidelines when contemplating use of these agents.

Down-regulation of DNA repair in human CD34(+) progenitor cells corresponds to increased drug sensitivity and apoptotic response

Although DNA repair processes have been shown to considerably modulate the cytotoxic effects of alkylating agents, little information is available on the role of these mechanisms in chemotherapy-induced myelosuppression. Therefore, we have analyzed in detail the DNA repair capacity of primary human hematopoietic cells from cord blood (CB) or bone marrow (BM) by 2 functional assays, the immunocytologic assay (ICA) and single-cell gel electrophoresis (comet assay). Besides substantial interindividual differences, we consistently observed significantly lower repair capacity of CD34(+) cells in comparison to CD34(-), CD19(+), or CD33(+) cells of the same donor. After exposure to the alkylating agent ethylnitrosourea (EtNU), the comet assay displayed on average twice as many DNA single-strand breaks (SSBs) in CD34(+) cells and a tripled half-life of these lesions in comparison to corresponding CD34(-) cells. Similarly, reduced SSB repair activity in CD34(+) cells was detected following melphalan or cisplatin application. When specific antibodies were used to monitor DNA reaction products of these drugs, adduct levels were significantly higher and lesions persisted longer in the CD34(+) fraction. To assess the contribution of individual pathways to overall DNA repair, modulators blocking defined steps in repair processes were coapplied with alkylating drugs. Similar "modulation pattern" in corresponding CD34(+) and CD34(-) cell fractions indicated a generalized reduction in DNA repair capacity of CD34(+) cells, rather than deficiencies in a specific pathway. Because CD34(+) cells also displayed higher frequencies of apoptosis in response to melphalan or cisplatin, these findings may help to explain the myelosuppression after exposure to alkylating agents.