Phase II study of exatecan mesylate (DX-8951f) as first line therapy for advanced non-small cell lung cancer

Empowering lung cancer treatment: Harnessing the potential of natural phytoconstituent-loaded nanoparticles

Lung cancer, the second leading cause of cancer-related deaths, accounts for a substantial portion, representing 18.4% of all cancer fatalities. Despite advances in treatment modalities such as chemotherapy, surgery, and immunotherapy, significant challenges persist, including chemoresistance, non-specific targeting, and adverse effects. Consequently, there is an urgent need for innovative therapeutic approaches to overcome these limitations. Natural compounds, particularly phytoconstituents, have emerged as promising candidates due to their potent anticancer properties and relatively low incidence of adverse effects compared to conventional treatments. However, inherent challenges such as poor solubility, rapid metabolism, and enzymatic degradation hinder their clinical utility. To address these obstacles, researchers have increasingly turned to nanotechnology-based drug delivery systems (DDS). Nanocarriers offer several advantages, including enhanced drug stability, prolonged circulation time, and targeted delivery to tumor sites, thereby minimizing off-target effects. By encapsulating phytoconstituents within nanocarriers, researchers aim to optimize their bioavailability and therapeutic efficacy while reducing systemic toxicity. Moreover, the integration of nanotechnology with phytoconstituents allows for a nuanced understanding of the intricate molecular pathways involved in lung cancer pathogenesis. This integrated approach holds promise for modulating key cellular processes implicated in tumor growth and progression. Additionally, by leveraging the synergistic effects of phytoconstituents and nanocarriers, researchers seek to develop tailored therapeutic strategies that maximize efficacy while minimizing adverse effects. In conclusion, the integration of phytoconstituents with nanocarriers represents a promising avenue for advancing lung cancer treatment. This synergistic approach has the potential to revolutionize current therapeutic paradigms by offering targeted, efficient, and minimally toxic interventions. Continued research in this field holds the promise of improving patient outcomes and addressing unmet clinical needs in lung cancer management.

Cancer therapies utilizing the camptothecins: a review of the in vivo literature

This review summarizes the in vivo assessment-preliminary, preclinical, and clinical-of chemotherapeutics derived from camptothecin or a derivative. Camptothecin is a naturally occurring, pentacyclic quinoline alkaloid that possesses high cytotoxic activity in a variety of cell lines. Major limitations of the drug, including poor solubility and hydrolysis under physiological conditions, prevent full clinical utilization. Camptothecin remains at equilibrium in an active lactone form and inactive hydrolyzed carboxylate form. The active lactone binds to DNA topoisomerase I cleavage complex, believed to be the single site of activity. Binding inhibits DNA religation, resulting in apoptosis. A series of small molecule camptothecin derivatives have been developed that increase solubility, lactone stability and bioavailability to varying levels of success. A number of macromolecular agents have also been described wherein camptothecin(s) are covalently appended or noncovalently associated with the goal of improving solubility and lactone stability, while taking advantage of the tumor physiology to deliver larger doses of drug to the tumor with lower systemic toxicity. With the increasing interest in drug delivery and polymer therapeutics, additional constructs are anticipated. The goal of this review is to summarize the relevant literature for others interested in the field of camptothecin-based therapeutics, specifically in the context of biodistribution, dosing regimens, and pharmacokinetics with the desire of providing a useful source of comparative data. To this end, only constructs where in vivo data is available are reported. The review includes published reports in English through mid-2009.

New cytotoxic agents: a review of the literature

The goal of treatment for patients with advanced cancer is to prolong survival, control symptoms, and reduce disease-related complications. Despite the introduction of many cytotoxic agents during the past decade, only modest improvement in survival has been achieved. In order to urgently improve these situations, new cytotoxic agents as well as molecular-targeted agents are now under investigation. In this article, we reviewed the latest information regarding antitumor activity, toxicity, pharmacokinetics, and clinical application of the new cytotoxic agents.

Activity of Novel Cytotoxic Agents in Lung Cancer: Epothilones and Topoisomerase I Inhibitors

The treatment of lung cancer--small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC)--is a significant challenge in oncology. The best reported median survival remains near 1 year in advanced NSCLC despite several decades of steady improvement and extensive research with traditional chemotherapy drugs and novel compounds targeted to different aspects of tumor cell growth and function (such as the epidermal growth factor receptor). Extensive-stage SCLC survival is only slightly better. Novel "targeted" therapeutic agents hold promise, but cytotoxic therapy remains the backbone of treatment. Many new cytotoxic agents are currently in development. In this review, we will focus on 2 classes of cytotoxins: epothilones and topoisomerase I inhibitors. Epothilones are microtubule stabilizers with a mechanism of action similar to that of the taxanes, with preclinical activity superior to that of the taxanes. Phase I trials have been completed for patupilone and ixabepilone, and there are encouraging phase II data with ixabepilone in NSCLC. A phase II trial of patupilone is ongoing. The camptothecins, which are topoisomerase I inhibitors, have a long history in the treatment of lung cancer, but the currently available drugs, topotecan and irinotecan, have limitations. Gimatecan and other novel camptothecins have superior preclinical activity and promising phase I/II data in NSCLC and SCLC.

DE-310, a macromolecular prodrug of the topoisomerase-I-inhibitor exatecan (DX-8951), in patients with operable solid tumors

BACKGROUND

DE-310 is composed of the topoisomerase-I-inhibitor DX-8951 (exatecan) and a biodegradable macromolecular carrier, which are covalently linked by a peptidyl spacer. In pre-clinical studies, high levels and prolonged retention of conjugated DX-8951 (carrier-bound DX-8951) have been observed in tumor tissues following DE-310 administration. This phenomenon is explained as the enhanced permeability and retention (EPR) effect. DX-8951 and G-DX-8951 (glycyl-DX-8951) exerting anti-tumor activity in vivo are released from DE-310 by enzymatic cleavage of the spacer.

METHODS

To quantify the concentration of conjugated DX-8951, DX-8951 and G-DX-8951 in human tissues, six patients with different solid tumor types received 6.0 mg/m(2) of DE-310 (as equivalent of DX-8951) as a single three-hour infusion administered 7 days (+/-2 days) prior to scheduled tumor resection. Drug concentrations were then determined in the resected tissues. To evaluate the plasma PK of DE-310, plasma samples were taken up to 42 days post dosing.

RESULTS

There were no severe side effects of the DE-310 infusion. Concentrations of conjugated DX-8951, DX-8951 and G-DX-8951 were in general similar in tumor and relevant normal tissue samples and preferential accumulation of DE-310, DX-8951 and G-DX-8951 in human tumor tissues was not observed.

CONCLUSIONS

These data indicate that there is distribution of DE-310 into tissue and that DX-8951 and G-DX-8951 are released slowly over an extended period from DE-310 providing prolonged exposure similar to a continuous infusion. However, the similarity in the concentrations in tumor and relevant normal tissues does not support the EPR concept in the studied human cancers.

A phase II trial with RFS2000 (rubitecan) in patients with advanced non-small cell lung cancer

Rubitecan (RFS2000, 9 nitrocamptothecin,) is a new oral topoisomerase I inhibitor. We report a phase II, single-arm, open-label study of RFS2000 as first line treatment for non-small cell lung cancer (NSCLC). Seventeen treatment-naïve patients with stage IIIB (9/17) and IV (8/17) NSCLC (11 male and 6 female) were treated, the median age was 62 years (range 52-86), and the majority of patients (14/17) were of performance status 1. RFS2000 was given orally, daily for 5 days, repeated every week. The starting dose was 1.5 mg/m(2)/day, and dose adjustment was permitted based upon toxicity. Fifteen patients had a dose escalation to 1.75 mg/m(2)/day and 7 had a second dose escalation to the protocol maximum level of 2.0 mg/m(2)/day. RFS2000 was tolerated well. Almost all adverse events were grade 1 and 2. The most frequently encountered adverse events were diarrhoea, nausea, anorexia, and lethargy. Neutropenia and thrombocytopenia were not observed in any patient. There were no responders to RFS2000 treatment, 10 patients had stable disease as their best response, whilst five had tumour progression. Two patients were not assessable for tumour response. The median survival time was 257 days (95% CI = 222-352). RFS2000 appears to be inactive at dose levels of 1.5-2.0 mg/m(2)/day in advanced NSCLC patients. Since only mild toxicity and no myelosuppression were encountered, these dose level are too low for this treatment-naïve patient population with NSCLC. Further studies at an increased dose would be required to identify whether this agent has merit in the treatment of NSCLC.