Elliptinium acetate in metastatic breast cancer--a phase II study

Ellipticine, its Derivatives: Re-evaluation of Clinical Suitability with the Aid of Drug Delivery Systems

Targeted drug delivery systems gave newer dimensions for safer and more effective use of therapeutic drugs, thus helping in circumventing the issues of toxicity and unintended drug accumulation. These ongoing developments in delivery systems can, in turn, bring back drugs that suffered various limitations, Ellipticine (EPT) being a candidate. EPT derivatives witnessed entry into clinical settings but failed to survive in clinics citing various toxic side effects. A large body of preclinical data deliberates the potency of drug delivery systems in increasing the efficiency of EPT/derivatives while decreasing their toxic side effects. Recent developments in drug delivery systems provide a platform to explore EPT and its derivatives as good clinical candidates in treating tumors. The present review deals with delivery mechanisms of EPT/EPT derivatives as antitumor drugs, in vitro and in vivo, and evaluates the suitability of EPT-carriers in clinical settings.

Adverse drug reactions of anticancer drugs derived from natural sources

Cancer, a life threatening disease adversely affects huge population worldwide. Naturally derived drug discovery has emerged as a potential pathway in search of anticancers. Natural products-based drugs are generally considered safe, compared to their synthetic counterparts. A systematic review on adverse drugs reactions (ADRs) of the anticancer natural products has not been performed till date. We reviewed anticancer drugs, derived from plants, microbes and marine sources with their mechanistic action and reported ADRs. PubMed, ScienceDirect and Scopus were searched through Boolean information retrieval method using keywords "natural products", "cancer", "herbal", "marine drugs" and "adverse drug reaction". We documented ADRs of natural products based anticancer agents, mechanisms of action and chemical structures. It was observed that majority of the natural products based anticancer drugs possess ample adverse effects, dominantly hematological toxicities, alopecia, neurotoxicity and cardiotoxicity. These findings deviate from the preconceived notion about safer nature of herbal drugs. We also came across some anti-cancer natural products with less/no reported adverse events like Cabazitaxel and Arglabin. Comprehensive pharmacovigilance studies are needed to report ADRs and thereby predicting safety of anti-cancer drugs, either originated from natural sources or chemically synthesized.

3-(Dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (DPA-HBFQ-1) plays an inhibitory role on breast cancer cell growth and progression

A series of unknown 3-(alkyl(dialkyl)amino)benzofuro[2,3-f]quinazolin-1(2H)-ones 4-17 has been synthesized as new ellipticine analogs, in which the carbazole moiety and the pyridine ring were replaced by a dibenzofuran residue and a pyrimidine ring, respectively. The synthesis of these benzofuroquinazolinones 4-17 was performed in a simple one-pot reaction using 3-aminodibenzofuran or its 2-methoxy derivative, as starting materials. From 3-(dipropylamino)-5-methoxybenzofuro[2,3-f] quinazolin-1(2H)-one (13), we prepared 3-(dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (18), referred to as DPA-HBFQ-1. The cytotoxic activities of all the synthesized compounds, tested in different human breast cancer cell lines, revealed that DPA-HBFQ-1 was the most active compound. In particular, the latter was able to inhibit anchorage-dependent and -independent cell growth and to induce apoptosis in estrogen receptor alpha (ERα)-positive and -negative breast cancer cells. It did not affect proliferation and apoptotic responses in MCF-10A normal breast epithelial cells. The observed effects have been ascribed to an enhanced p21(Cip1/WAF1) expression in a p53-dependent manner of tumor suppressor and to a selective inhibition of human topoisomerase II. In addition, DPA-HBFQ-1 exerted growth inhibitory effects also in other cancer cell lines, even though with a lower cytotoxic activity. Our results indicate DPA-HBFQ-1 as a good candidate to be useful as cancer therapeutic agent, particularly for breast cancer.

Rescue of mutant p53 transcription function by ellipticine

The p53 tumor suppressor is frequently inactivated in tumors by point mutations in the DNA-binding domain, resulting in loss of sequence-specific DNA binding and transcription function. We present evidence that ellipticine can restore the transactivation function of several transfected p53 mutants (175 H, 248W, 249S, 273 H, 281G), resulting in the induction of p53-responsive genes (p21(WAF1),MDM2) and activation of a p53-responsive luciferase reporter. Ellipticine also activates mutant p53 function in tumor cells expressing endogenous 194F, 233L, 241F, and 273C mutants. Treatment with ellipticine alters mutant p53 reactivity to conformation-sensitive Pab1620 and Pab240 antibodies and increases its sequence-specific DNA-binding activity in vivo. Finally, ellipticine activates mutant p53 and induces p21(WAF1) and MDM2 expression in nude mouse tumor xenografts. These results demonstrate that ellipticine can restore transcription function to mutant p53. This property may contribute to the selectivity of ellipticine-derived compounds against tumor cell lines expressing mutant p53.

Topoisomerase II binds to ellipticine in the absence or presence of DNA. Characterization of enzyme-drug interactions by fluorescence spectroscopy

Although a number of drugs currently in use for the treatment of human cancers act by stimulating topoisomerase II-mediated DNA breakage, little is known regarding interactions between these agents and the enzyme. To further define the mechanism of drug action, interactions between ellipticine (an intercalative drug with clinical relevance) and yeast topoisomerase II were characterized. By utilizing a yeast genetic system, topoisomerase II was identified as the primary cellular target of the drug. Furthermore, ellipticine did not inhibit enzyme-mediated DNA religation, suggesting that it stimulates DNA breakage by enhancing the forward rate of cleavage. Finally, ellipticine binding to DNA, topoisomerase II, and the enzyme-DNA complex was assessed by steady-state and frequency domain fluorescence spectroscopy. As determined by changes in fluorescence intensity and emission maximum wavelength, and by lifetime analysis, only the protonated species of ellipticine bound to a double-stranded 40-mer oligonucleotide containing a topoisomerase II cleavage site (KD approximately 65 nM). In contrast, predominantly deprotonated ellipticine bound to the enzyme.DNA complex (KD approximately 1.5 microM) or to the enzyme in the absence of nucleic acids (KD approximately 160 nM). These findings suggest that ellipticine interacts directly with topoisomerase II and that the enzyme dictates the ionic state of the drug in the ternary complex. A model is presented in which the topoisomerase II.ellipticine.DNA complex is formed via initial drug binding to either the enzyme or DNA.

Phase II study of elliptinium acetate salvage treatment of advanced breast cancer

Elliptinium acetate (Celiptium) is an intercalating agent belonging to the ellipticine family. This agent has demonstrated clinical activity as salvage treatment in breast cancer using a weekly regimen. However, its clinical use was hampered by important toxicities such as xerostomia and immune-mediated haemolytic reactions due to development of anti-elliptinium IgM antibodies. We have studied 83 patients previously treated for metastatic breast cancer using elliptinium acetate with a different schedule: 80 mg/m2 daily for 3 consecutive days every 21 days. In 80 evaluable patients, an objective response (complete + partial response) was obtained in 5 of 30 patients with visceral metastases (13%), in 6 of 21 patients with soft tissue metastases (29%), and in 3 of 20 patients with mixed metastases (15%). The overall objective response rate was 14/80 (18%, 95% confidence interval = 10-26%). Moderate to severe xerostomia occurred in 10% of patients, while no anti-elliptinium antibodies or haemolytic reactions were detected using this schedule. No significant haematological toxicity, as usually reported with this drug, was observed. Elliptinium acetate has modest but definite activity as salvage treatment of breast cancer. The 3-week schedule seems as active as and less toxic than the weekly schedule.

Phase II study of a combination of elliptinium and vinblastine in metastatic breast cancer

Thirty nine patients with metastatic breast cancer, all previously treated with chemotherapy including anthracycline, were given Elliptinium acetate (80 mg/m2/day) and a continuous infusion of Vinblastine (2 mg/m2/day) for 3 consecutive days every 4 weeks. Twenty nine patients had measurable metastatic disease. Nine (31%) achieved a partial response. No complete response was observed. Median duration of response was 6 months. The response rate was dependent on the number of metastatic sites and independent of the number of previous chemotherapy regimes. Side effects were dry mouth (27 patients), vomiting (9), neutropenia (3 patients with grade IV, 2 with grade III), muscle cramps (5) and thrombosis (3). Xerostomia and vomiting contributed to weight loss and fatigue (8 patients). We conclude that Elliptinium-Vinblastine combination has moderate activity as second line treatment in metastatic breast cancer. This combination causes xerostomia and fatigue with moderate myelosuppression.

Overview of new treatments for breast cancer

Progress in the treatment of breast cancer developed along multiple directions of research during the last decade. The concept of dose-intensity was addressed through retrospective analyses and prospective randomized trials. It was confirmed that dose-intensity correlates with higher response rates, but the effect of dose-intensive treatments on survival still needs to be established. Several new cytotoxic drugs have appeared during the last several years. Taxol, navelbine, and anthrapyrazole CI-941 have been found to have major efficacy against breast cancer, with response rates exceeding 50%. Amonafide, lonidamine, and elliptinium analogs were also shown to be effective, although to a lesser degree. Antiestrogen analogs, new aromatase inhibitors, and LHRH analogs are recent developments that are changing the face of hormonal therapy. Monoclonal antibodies are being developed and evaluated for tumor imaging applications and as vehicles for specific antitumor agents (cytotoxics, radioisotopes, and toxins). Expanding knowledge about the basic biology of breast cancer has led to the identification of growth factors and their receptors, which may be exploited for therapeutic purposes in the not too distant future.

Phase I study of Datelliptium chloride, hydrochloride given by 24-h continuous intravenous infusion

Datelliptium chloride, hydrochloride (SR 95 156B, NSC 626718X, DHE) was studied in a phase I trial of escalating doses given on a single 24-h continuous intravenous infusion schedule. Doses were escalated from 40 to 500 mg/m2 in 19 patients who received a total of 24 courses. Courses were repeated after a minimal interval of 3 weeks. Local venous toxicity occurred at low doses (less than or equal to 100 mg/m2) and was circumvented by the use of a central venous access for higher doses. Other clinical adverse events occurred (greater than or equal to 330 mg/m2), including moderate nausea and vomiting, mild diarrhea, dry mouth, neuropsychiatric manifestations, and fatigue. All of these side effects were reversible and none was dose-limiting. The dose-limiting toxicity was related to hepatic laboratory-test abnormalities in the form of reversible elevations of levels of serum bilirubin and liver enzymes at doses of greater than or equal to 330 mg/m2. The maximum tolerated dose for this schedule is 500 mg/m2. Hematologic toxicity was minimal and non-dose-limiting. Neither drug-related deaths nor objective complete or partial responses were observed. However, a minor response and a long-term disease stabilization were obtained.