What is the role of novel taxanes in non-small-cell lung cancer?

The taxanes are among the most active cytotoxic agents in oncology and are widely used in adjuvant and advanced treatment settings in multiple tumor types. Paclitaxel and docetaxel are standard therapies in advanced non-small-cell lung cancer (NSCLC) and are increasingly used in earlier treatment settings. The taxanes are generally well tolerated but can be associated with severe, irreversible (and rarely life-threatening) toxicity. Premedication and special infusion sets are necessary to reduce the risk of hypersensitivity reactions. Newer taxanes are in development designed to improve the therapeutic index and ease of administration. Several agents have completed phase I/II clinical trials and are in phase III testing. Many other novel taxanes are at earlier stages of development and appear promising as single agents and in combination regimens. Safer and more effective taxanes could replace paclitaxel and docetaxel as standard treatments in NSCLC.

Non-allergic nature of docetaxel-induced acute hypersensitivity reactions

Based on observations of a discrepancy between 'hypersensitivity' reactions to docetaxel (DT) and the clinical features of allergic reactions, we explored the hypothesis that DT-induced acute hypersensitivity reactions (AHRs) have a non-allergic origin. Forty cancer patients receiving DT and 16 patients receiving other potentially allergenic chemotherapeutic agents were included in the study. All DT patients received standard pre- and post-medication. Before, during and after administration of the drugs, clinical symptoms and signs were recorded, and serial blood sampling was performed for the first 2 cycles for all patients or in all subsequent cycles in case of AHRs. Plasma histamine and serum tryptase, two established drug allergy markers, were measured. Seventy-five chemotherapy sessions were evaluable. Nine patients on DT, two on paclitaxel (PT) and one on pegylated doxorubicin experienced an AHR during the first course of chemotherapy. In all cases, heart rate remained stable or increased, while arterial pressure was unchanged or raised; no hypotension or bradycardia was noted. All episodes resolved with discontinuation of drug and did not reappear during a re-challenge with the same agent 30 min later. Tryptase levels were normal in all pre- and post-exposure samples (post-exposure: 11.32+/-35.63 microg/l, normal values <13.5 microg/l). In all but one AHR-free PT, pre- and post-exposure histamine concentrations remained normal (post-exposure: 2.86+/-11.88 nM, normal values <10 nM). No eosinophilia or basophilia was observed. We conclude that 'hypersensitivity' reactions to DT seem not to be histamine or tryptase mediated; thus, their allergenic nature should be questioned. The underlying mechanism may be related to other biological processes such as the release of vasoactive molecules or non-histamine/tryptase-mediated allergy. If the former is demonstrated by further study, the safety of DT administration will be confirmed, and the pre- and post-medication practice might be revisited.

Paclitaxel and its formulations

Paclitaxel (Taxol) is a promising anti-tumor agent with poor water solubility. It is effective for various cancers especially ovarian and breast cancer. Intravenous administration of a current formulation in a non-aqueous vehicle containing Cremophor EL may cause allergic reactions and precipitation on aqueous dilution. Moreover, the extensive clinical use of this drug is somewhat delayed due to the lack of appropriate delivery vehicles. Due to this there is a need for the development of alternate formulation of paclitaxel having good aqueous solubility and at the same time free of any side effects. Various approaches employed so far include cosolvents, emulsions, micelles, liposomes, microspheres nanoparticles, cyclodextrins, pastes, and implants etc. which are discussed in this paper.