H2 O2 -Inducible DNA Cross-linking Agents Capable of Releasing Multiple DNA Alkylators as Anticancer Prodrugs.

Three compounds with arylboronate esters conjugated with two equivalent nitrogen mustards [bis(2-chloroethyl)methylamine, HN2] have been synthesized and characterized. These inactive small molecules selectively react with H2 O2 to produce multiple DNA cross-linkers, such as two HN2 molecules alongside a bisquinone methide (bisQM), leading to efficient DNA ICL formation. In comparison to other amine functional groups, using HN2 as a leaving group greatly improves the DNA cross-linking efficiency of these arylboronate esters as well as cellular activity. The introduction of HN2 in these arylboronate ester analogues favored the generation of bisQM that can directly cross-link DNA. Two equivalents of HN2 are also generated from these compounds upon treatment with H2 O2 , which directly produces DNA ICL products. The cumulative effects of HN2 and bisQM on DNA cross-linking makes these molecules highly effective H2 O2 -inducible DNA ICL agents. The three compounds with HN2 as a leaving group showed greatly enhanced cytotoxicity towards cancer cells in comparison to those containing trimethyl amine as a leaving group. This provides an effective strategy for further design of novel potential ROS-activated anticancer prodrugs.

Design, synthesis and anticancer evaluation of novel oncolytic peptide-chlorambucil conjugates.

Nitrogen mustards (NMs) are an important class of chemotherapeutic drugs and have been widely employed for the treatment of various cancers. However, due to the high reactivity of nitrogen mustard, most NMs react with proteins and phospholipids within the cell membrane. Therefore, only a very small fraction of NMs can reach the reach nucleus, alkylating and cross-linking DNA. To efficiently penetrate the cell membrane barrier, the hybridization of NMs with a membranolytic agent may be an effective strategy. Herein, the chlorambucil (CLB, a kind of NM) hybrids were first designed by conjugation with membranolytic peptide LTX-315. However, although LTX-315 could help large amounts of CLB penetrate the cytomembrane and enter the cytoplasm, CLB still did not readily reach the nucleus. Our previous work demonstrated that the hybrid peptide NTP-385 obtained by covalent conjugation of rhodamine B with LTX-315 could accumulate in the nucleus. Hence, the NTP-385-CLB conjugate, named FXY-3, was then designed and systematically evaluated both in vitro and in vivo. FXY-3 displayed prominent localization in the cancer cell nucleus and induced severe DNA double-strand breaks (DSBs) to trigger cell apoptosis. Especially, compared with CLB and LTX-315, FXY-3 exhibited significantly increased in vitro cytotoxicity against a panel of cancer cell lines. Moreover, FXY-3 showed superior in vivo anticancer efficiency in the mouse cancer model. Collectively, this study established an effective strategy to increase the anticancer activity and the nuclear accumulation of NMs, which will provide a valuable reference for future nucleus-targeting modification of nitrogen mustards.

Bendamustine: A review of pharmacology, clinical use and immunological effects (Review).

Bendamustine is an alkylating agent classified into the group of nitrogen mustard analogues, synthesized almost sixty years ago. It was registered in former East Germany in 1971 and approved by the US Food and Drug Administration in 2008 for treatment of chronic lymphocytic leukemia and indolent B­cell non­Hodgkin lymphoma. Considering its beneficial properties in the therapy of relapsed or refractory hematological malignancies, synergistic effects with other antineoplastic agents and increasing recent reports on its immunomodulatory effects, bendamustine has once again gained its justified attention. The uniqueness of bendamustine­mediated effects should be observed keeping in mind its distinctive structure with structural similarities to both alkylating agents and purine analogs. In the present review, the current knowledge on the use of bendamustine in oncology, its pharmacokinetics, mechanism of action and toxicity was summarized. In addition, its immune­modulating effects that have not been fully elucidated so far are emphasized, hoping to encourage further investigations of this unique drug.

In Vitro Evaluation of DNA Damage Effect Markers toward Five Nitrogen Mustards Based on Liquid Chromatography-Tandem Mass Spectrometry.

Endogenous DNA lesions frequently occur due to internal effects such as oxidative stress, inflammation, endogenous alkylation, and epigenetic modifications. However, exposure to chemical toxicants from the environment, diet, or drugs can also induce significant endogenous DNA damage. The quantification of endogenous DNA damage effect markers might reflect the actual DNA damage level of chemical toxicants. Herein, we report a liquid chromatography-triple quadrupole tandem mass spectrometry (LC-QqQ MS/MS) method for simultaneous determination of eight representative endogenous DNA damage biomarkers, including five endogenous DNA damage effect markers (oxidative damage, 8-oxo-dG; lipid peroxidation, εdA and N2-Et-dG; inflammation, 5-Cl-dC; and endogenous alkylation, O6-Me-dG), and three epigenetic modifications (5-m-dC, 5-hm-dC, and N6-Me-dA). The method validation was performed, and the linear range was 0.05 pg to 2 ng (on-column), the limit of detection was 0.02 pg (on-column), and the precision, accuracy, matrix effect, and recovery were all between 85 and 115%. We then applied this method to evaluate endogenous DNA damage to human embryonic lung fibroblast cells exposed to five nitrogen mustards [NMs, i.e., HN1, HN2, HN3, chlorambucil (CB), and cyclophosphamide (CTX)], where curcumin exposure was used as a control due to its inability to induce the formation of endogenous DNA adducts. The amounts of eight DNA adducts in the low-, middle-, and high-concentration exposure groups of five NMs were almost all significantly different from those in the blank group (P < 0.05). We obtained a positive correlation between the contents of eight DNA damage biomarkers and the inhibition dose of five NMs, except for N2-Et-dG and 5-Cl-dC. Via further principal component analysis and partial least squares discriminant analysis, we clustered all NMs into three units with different cytotoxicity levels, that is, HN2 and HN1 (highly toxic), HN3 and CB (moderately toxic), and CTX (less toxic). Moreover, for the same concentration of HN1/2/3 exposure groups, as the cytotoxicity increased according to the order of HN3 < HN1 < HN2, the contents of 8-oxo-dG, 5-m-dC, 5-hm-dC, and N6-Me-dA increased, whereas the content of O6-Me-dG decreased. Therefore, the contents of these DNA damage effect markers were somewhat related to the cytotoxicity and concentration of NMs. We hope that this method will provide an alternative evaluation approach for the toxicological effects of NMs and the safety of the medication.

Coupling of a Novel TIMP3 Peptide to Carboxypeptidase G2 for Pro-Drug Activation at the Tumour Site.

Broad-spectrum cytotoxic drugs have been used in cancer therapy for decades. However, their lack of specificity to cancer cells often results in serious side-effects, limiting efficacy. For this reason, antibodies have been used to attempt to specifically target cytotoxic drugs to tumours. One such approach is antibody-directed enzyme prodrug therapy (ADEPT) which uses a tumour-directed monoclonal antibody, coupled to an enzyme, to convert a systemically administered non-toxic prodrug into a toxic one only at the tumour site. Among the main drawbacks of ADEPT is the immunogenicity of the antibody-enzyme complex, which is exacerbated by slow clearance due to size, hence limiting repeated administration. Additionally, the mono-specificity of the antibody could potentially result in drug resistance with repeated administration. We have identified a novel short peptide sequence, p700, derived from a human tissue inhibitor of metalloproteinases-3 (TIMP-3), which binds to and inhibits a number of tyrosine kinase growth factor receptors (VEGFRs1-3, FGFRs 1-4 and PDGFRα) which are known to be upregulated in many tumours and tumour vasculature. In this report, we fused p700 to His-tagged, codon-optimised, carboxypeptidase G2 (CPG2). CPG2 is a bacterial enzyme used in ADEPT, which activates potent nitrogen-mustard pro-drugs by removal of an inhibitory glutamic acid residue. Recombinant CPG2-p700 was highly expressed in Escherichia coli and successfully purified by nickel affinity chromatography. Biolayer interferometry showed that CPG2-p700 had a 100-fold increase in binding affinity for VEGFR2 compared with CPG2 alone and retained its catalytic activity, as determined by methotrexate cleavage. In the presence of CPG2-p700, the ZD2676P pro-drug showed significant cytotoxicity for 4T1 cells compared with prodrug alone or CPG2 alone. p700 is, therefore, a potentially useful alternative to monoclonal antibodies for enzyme pro-drug therapy and could equally be used for effective delivery of other cytotoxic drugs to tumour tissue.

Aldophosphamide-thiazolidine (NSC-613060) an oxazaphosphorine cytostatic that crosses the blood brain barrier.

The pharmacologically active metabolite of cyclophosphamide is aldophosphamide. With cysteine, aldophosphamide forms stable aldophosphamide-thiazolidine which under physiological pH and temperature conditions hydrolyzes to aldophosphamide and cysteine. Aldophosphamide-thiazolidine was synthesized and tested for its ability as a cytostatic. The LD50 after a single intraperitoneal injection in mice was determined to be 2162 mg/kg, but after intravenous bolus administration of 500 mg/kg or in chronic toxicity tests with daily intraperitoneal injections, neurological side effects were observed. Antitumor activity was determined in therapy experiments in CD2F1 mice bearing subcutaneously transplanted P388 mouse leukemia cells. Administration of 100 mg/kg (less than 5% LD50) days 1-5 after tumor transplantation yielded an ILS of 100%. Organ distribution studies showed that aldophosphamide-thiazolidine is evenly distributed in all tissues examined, including brain tissue. The possibilities to increase the antitumor activity of aldophosphamide-thiazolidine by modulating the alkylating function are discussed.

Synthesis and evaluation of new dinitrobenzamide mustards in human prostate cancer.

Tumor hypoxia has been widely explored over the years as a diagnostic and therapeutic marker. Herein, we have reported the design and synthesis of a series of dinitrobenzamide mustards (DNBM) based on the PR-104A hypoxia-selective prodrug. Specifically, we explored the impact of various leaving groups and the introduction of a carboxylic acid group on the biological performance of the DNBM constructs. Once in hand, the Log D values, cytotoxicity in PC-3 and DU-145 human prostate cancer cells lines and the hypoxia selectivities of the DNBM analogs were examined. Overall, the DNBM constructs were found to be tolerant to modifications with none of the explored modifications substantially degrading the cytotoxic potential of the constructs.

Derivatives of nitrogen mustard anticancer agents with improved cytotoxicity.

In previous studies, we demonstrated that esters of bendamustine containing a basic moiety are far more cytotoxic anticancer agents than their parent compound and that the substitution of the labile ester moiety by a branched ester or an amide markedly increases stability in the blood plasma. In the current study, we showed that this substitution was bioisosteric. Aiming at increased cytotoxicity, we introduced the same modification to related nitrogen mustards: 6-isobendamustine, chlorambucil, and melphalan. The synthesis was accomplished using the coupling reagents N,N'-dicyclohexylcarbodiimide or 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethylaminium tetrafluoroborate. Cytotoxicity against a panel of diverse cancer cells (carcinoma, sarcoma, and malignant melanoma) was assessed in a kinetic chemosensitivity assay. The target compounds showed cytotoxic or cytocidal effects at concentrations above 1 µM: a striking enhancement over bendamustine and 6-isobendamustine, both ineffective against the selected cancer cells at concentrations up to 50 µM, and a considerable improvement over chlorambucil, showing some potency only against the sarcoma cells. Melphalan was almost as effective as the target compounds-derivatization only provided a small improvement. The novel cytostatics are of interest as model compounds for analyzing a correlation between cytotoxicity and membrane transport and for the treatment of malignancies.

E. coli nitroreductase NfsA is a reporter gene for non-invasive PET imaging in cancer gene therapy applications.

The use of reporter genes to non-invasively image molecular processes inside cells has significant translational potential, particularly in the context of systemically administered gene therapy vectors and adoptively administered cells such as immune or stem cell based therapies. Bacterial nitroreductase enzymes possess ideal properties for reporter gene imaging applications, being of non-human origin and possessing the ability to metabolize a range of clinically relevant nitro(hetero)cyclic substrates. Methods: A library of eleven Escherichia coli nitroreductase candidates were screened for the ability to efficiently metabolize 2-nitroimidazole based positron emission tomography (PET) probes originally developed as radiotracers for hypoxic cell imaging. Several complementary methods were utilized to detect formation of cell-entrapped metabolites, including various in vitro and in vivo models to establish the capacity of the 2-nitroimidazole PET agent EF5 to quantify expression of a nitroreductase candidate. Proof-of-principle PET imaging studies were successfully conducted using 18F-HX4. Results: Recombinant enzyme kinetics, bacterial SOS reporter assays, anti-proliferative assays and flow cytometry approaches collectively identified the major oxygen-insensitive nitroreductase NfsA from E. coli (NfsA_Ec) as the most promising nitroreductase reporter gene. Cells expressing NfsA_Ec were demonstrably labelled with the imaging agent EF5 in a manner that was quantitatively superior to hypoxia, in monolayers (2D), multicellular layers (3D), and in human tumor xenograft models. EF5 retention correlated with NfsA_Ec positive cell density over a range of EF5 concentrations in 3D in vitro models and in xenografts in vivo and was predictive of in vivo anti-tumor activity of the cytotoxic prodrug PR-104. Following PET imaging with 18F-HX4, a significantly higher tumor-to-blood ratio was observed in two xenograft models for NfsA_Ec expressing tumors compared to the parental tumors thereof, providing verification of this reporter gene imaging approach. Conclusion: This study establishes that the bacterial nitroreductase NfsA_Ec can be utilized as an imaging capable reporter gene, with the ability to metabolize and trap 2-nitroimidazole PET imaging agents for non-invasive imaging of gene expression.

Bypass of DNA interstrand crosslinks by a Rev1-DNA polymerase ζ complex.

DNA polymerase ζ (Pol ζ) and Rev1 are essential for the repair of DNA interstrand crosslink (ICL) damage. We have used yeast DNA polymerases η, ζ and Rev1 to study translesion synthesis (TLS) past a nitrogen mustard-based interstrand crosslink (ICL) with an 8-atom linker between the crosslinked bases. The Rev1-Pol ζ complex was most efficient in complete bypass synthesis, by 2-3 fold, compared to Pol ζ alone or Pol η. Rev1 protein, but not its catalytic activity, was required for efficient TLS. A dCMP residue was faithfully inserted across the ICL-G by Pol η, Pol ζ, and Rev1-Pol ζ. Rev1-Pol ζ, and particularly Pol ζ alone showed a tendency to stall before the ICL, whereas Pol η stalled just after insertion across the ICL. The stalling of Pol η directly past the ICL is attributed to its autoinhibitory activity, caused by elongation of the short ICL-unhooked oligonucleotide (a six-mer in our study) by Pol η providing a barrier to further elongation of the correct primer. No stalling by Rev1-Pol ζ directly past the ICL was observed, suggesting that the proposed function of Pol ζ as an extender DNA polymerase is also required for ICL repair.

Oral Administration of Cannabis and Δ-9-tetrahydrocannabinol (THC) Preparations: A Systematic Review.

BACKGROUND AND OBJECTIVE: Changes in cannabis legalization regimes in several countries have influenced the diversification of cannabis use. There is an ever-increasing number of cannabis forms available, which are gaining popularity for both recreational and therapeutic use. From a therapeutic perspective, oral cannabis containing Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is a promising route of administration but there is still little information about its pharmacokinetics (PK) effects in humans. The purpose of this systematic review is to provide a general overview of the available PK data on cannabis and THC after oral administration. METHODS: A search of the published literature was conducted using the PubMed database to collect available articles describing the PK data of THC after oral administration in humans. RESULTS: The literature search yielded 363 results, 26 of which met our inclusion criteria. The PK of oral THC has been studied using capsules (including oil content), tablets, baked goods (brownies and cookies), and oil and tea (decoctions). Capsules and tablets, which mainly correspond to pharmaceutical forms, were found to be the oral formulations most commonly studied. Overall, the results reflect the high variability in the THC absorption of oral formulations, with delayed peak plasma concentrations compared to other routes of administration. CONCLUSIONS: Oral THC has a highly variable PK profile that differs between formulations, with seemingly higher variability in baked goods and oil forms. Overall, there is limited information available in this field. Therefore, further investigations are required to unravel the unpredictability of oral THC administration to increase the effectiveness and safety of oral formulations in medicinal use.

Inactivation of Plasmodium falciparum in whole blood using the amustaline and glutathione pathogen reduction technology.

BACKGROUND: Risk of transfusion-transmitted (TT) malaria is mainly associated with whole blood (WB) or red blood cell (RBC) transfusion. Risk mitigation relies mostly on donor deferral while a limited number of countries perform blood testing, both negatively impacting blood availability. This study investigated the efficacy of the pathogen reduction system using amustaline and glutathione (GSH) to inactivate Plasmodium falciparum in WB. STUDY DESIGN AND METHODS: WB units were spiked with ring stage P. falciparum infected RBCs. Parasite loads were measured in samples at time of infection, after 24 hours at room temperature (RT), and after a 24-hour incubation at RT post-treatment with 0.2 mM amustaline and 2 mM GSH. Serial 10-fold dilutions of the samples were inoculated to RBC cultures and maintained up to 4 weeks. Parasitemia was quantified by cytometry. RESULTS: The P. falciparum viability assay has a limit of detection of a single live parasite per sample. Input parasite titer was >5.7 log10 TCID50 per mL. A 24-hour incubation at RT paused parasite development in controls, but they retained viability and infectivity when tested in culture. In contrast, no infectious parasites were detected in the amustaline/GSH-treated sample after 4 weeks of culture. CONCLUSION: A robust level of P. falciparum inactivation was achieved in WB using amustaline/GSH treatment. Parasite log reduction was >5.7 log10 TCID50 per mL. Development of such a pathogen reduction system may provide an opportunity to reduce the risk of TT malaria and improve blood availability.

Synthesis of flavonoids nitrogen mustard derivatives and study on their antitumor activity in vitro.

Several novel flavonoids nitrogen mustard derivatives were synthesized and evaluated for antiproliferative activity against seven human cancer cell lines (HeLa, A549, HepG2, MCF7, SH-SY5Y, PC-3, DU145) by the MTT assay in vitro. The resulting IC50 showed that most compounds exhibited better inhibitory activity against seven cell lines. IC50 values of some compounds were lower than well-known melphalan. In particular, compound 8b was the most promising compound which inhibited HeLa cells with IC50 value of 1.43 µM. It showed excellent antitumor activity against these seven cell lines. Besides, it could arrest cell cycle of HeLa in G2/M phase and induce cell apoptosis. The loss of mitochondrial membrane potential may be an apoptotic mediating factor.

Preclinical safety assessment of pathogen reduced red blood cells treated with amustaline and glutathione.

BACKGROUND: The nucleic acid targeted pathogen reduction (PR) system utilizing amustaline (S-303) and glutathione (GSH) is designed to inactivate blood-borne pathogens and leukocytes in red blood cell concentrates (PR-RBCC). Inactivation is attained after amustaline intercalates and forms covalent nucleic acid adducts preventing replication, transcription, and translation. After pathogen inactivation, amustaline spontaneously hydrolyzes to S-300, the primary negatively charged reaction product; amustaline is below quantifiable levels in PR-RBCC. GSH quenches free unreacted amustaline. STUDY DESIGN AND METHODS: The genotoxic and carcinogenic potential of PR-RBCC, the reaction by-products, and S-300 were assessed in accordance with the International Conference on Harmonization (ICH) guidelines and performed in compliance with the Food and Drug Administration (FDA) good laboratory practice standards, 21 CFR Part 58. in vitro bacterial reverse mutagenicity and chromosomal aberration assays were performed with and without exogenous S9 metabolic activation, and in in vivo clastogenicity and carcinogenic assays using validated murine models. RESULTS: PR-RBCCs were not genotoxic in vitro and in vivo and were non-carcinogenic in p53+/- transgenic mice transfused over 26 weeks. Estimated safety margins for human exposure ranged from >90 to >36 fold for 2 to 5 PR-RBCCs per day, respectively. PR-RBCCs and S-300 did not induce chromosome aberration in the in vivo murine bone marrow micronucleus assay at systemically toxic doses. CONCLUSIONS: PR-RBCCs did not demonstrate genotoxicity in vitro or in vivo and were not carcinogenic in vivo. These studies support the safety of PR-RBCCs and suggest that there is no measurable genotoxic hazard associated with transfusion of PR-RBCCs.

Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations.

Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.

Nitrogen Mustards as Anticancer Chemotherapies: Historic Perspective, Current Developments and Future Trends.

Nitrogen mustards, a family of DNA alkylating agents, marked the start of cancer pharmacotherapy. While traditionally characterized by their dose-limiting toxic effects, nitrogen mustards have been the subject of intense research efforts, which have led to safer and more effective agents. Even though the alkylating prodrug mustards were first developed decades ago, active research on ways to improve their selectivity and cytotoxic efficacy is a currently active topic of research. This review addresses the historical development of the nitrogen mustards, outlining their mechanism of action, and discussing the improvements on their therapeutic profile made through rational structure modifications. A special emphasis is made on discussing the nitrogen mustard prodrug category, with Cyclophosphamide (CPA) serving as the main highlight. Selected insights on the latest developments on nitrogen mustards are then provided, limiting such information to agents that preserve the original nitrogen mustard mechanism as their primary mode of action. Additionally, future trends that might follow in the quest to optimize these invaluable chemotherapeutic medications are succinctly suggested.

Nitrogen Mustards as Alkylating Agents: A Review on Chemistry, Mechanism of Action and Current USFDA Status of Drugs.

BACKGROUND & OBJECTIVE: Nitrogen mustard derivatives form one of the major classes of anti-cancer agents in USFDA approved drugs list. These are polyfunctional alkylating agents which are distinguished by a unique mechanism of adduct formation with DNA involving cross-linking between guanine N-7 of one strand of DNA with the other. The generated cross-linking is irreversible and leads to cell apoptosis. Hence it is of great interest to explore this class of anticancer alkylating agents. METHODS: An exhaustive list of reviews, research articles, patents, books, patient information leaflets, and orange book is presented and the contents related to nitrogen mustard anti-cancer agents have been reviewed. Attempts are made to present synthesis schemes in a simplified manner. The mechanism of action of the drugs and their side effects are also systematically elaborated. RESULTS: This review provides a platform for understanding all aspects of such drugs right from synthesis to their mechanism of action and side effects, and lists USFDA approved ANDA players among alkylating anticancer agents in the current market. CONCLUSION: Perusing this article, generic scientists will be able to access literature information in this domain easily to gain insight into the nitrogen mustard alkylating agents for further ANDA development. It will help the scientific and research community to continue their pursuit for the design of newer and novel heterocyclic alkylating agents of this class in the coming future.

The cellular effects of novel triazine nitrogen mustards in glioblastoma LBC3, LN-18 and LN-229 cell lines.

1,3,5-triazine is an important heterocyclic skeleton for mono, two or three 2-chloroethylamine groups. The study presented here provides novel information on cellular effects of 1,3,5-triazine with mono, two or three 2-chloroethylamine groups in glioblastoma LBC3, LN-18 and LN-229 cell lines. In our study, the most cytotoxic effect was observed in 1,3,5-triazine with three 2-chloroethylamine groups (12f compound). It has been demonstrated that 12f induce time- and dose-dependent cytotoxicity in all investigated glioma cell lines. Apart from that in glioblastoma cells, treated with 12f compound, we noticed strong induction of apoptosis. In conclusion, this research provides novel information concerning cellular effects of apoptosis in LBC3, LN-18 and LN-229 cell lines. Moreover, we suggest that 12f compound may be a candidate for further evaluation as an effective chemotherapeutic agent for human glioblastoma cells.

Discovery and Optimization of Novel Hydrogen Peroxide Activated Aromatic Nitrogen Mustard Derivatives as Highly Potent Anticancer Agents.

We describe several new aromatic nitrogen mustards with various aromatic substituents and boronic esters that can be activated with H2O2 to efficiently cross-link DNA. In vitro studies demonstrated the anticancer potential of these compounds at lower concentrations than those of other clinically used chemotherapeutics, such as melphalan and chlorambucil. In particular, compound 10, bearing an amino acid ester chain, is selectively cytotoxic toward breast cancer and leukemia cells that have inherently high levels of reactive oxygen species. Importantly, 10 was 10-14-fold more efficacious than melphalan and chlorambucil for triple-negative breast-cancer (TNBC) cells. Similarly, 10 is more toxic toward primary chronic-lymphocytic-leukemia cells than either chlorambucil or the lead compound, 9. The introduction of an amino acid side chain improved the solubility and permeability of 10. Furthermore, 10 inhibited the growth of TNBC tumors in xenografted mice without obvious signs of general toxicity, making this compound an ideal drug candidate for clinical development.

Biochemistry of N-mustard tumour control compounds reconsidered.

The biochemicals and reactions involved in the present mechanism of degradation of tumour cells during chemotherapy are reconsidered and limitations noted. Alternative mechanisms and treatment methods are detailed.