Antitumor Activity, Pharmacology, and Toxicity of Ellipticines, Ellipticinium, and 9-Hydroxy Derivatives: Preliminary Clinical Trials of 2-Methyl-9-Hydroxy Ellipticinium (NSC 264-137)

Abstract

Ellipticine and some derivatives are highly cytotoxic substances which kill L1210 cells at concentrations ranging form 10^-8 to 10^-6 M. Some compounds in this series bind with high affinity to DNA (affinity constant between 10⁷ M ^-1 and 10⁵ M ^-1) by intercalation between base pairs. The antitumoral properties of these derivatives are thought to be related to their DNA-binding ability. Both 9-hydroxylation of ellipticine and quaternarization of 2-pyridinic nitrogen tend to increase DNA binding and antitumor activity. 2-Methyl-9-hydroxyellipticine (NSC 264-137) was selected for a phase I and later for a phase II trial in human cancer. This drug does not affect blood cell counts in animals or in man. It is not mutagenic in the Ames’ test nor teratogenic in mice, but is endowed with anti-inflammatory properties and induces a marked decrease of motoricity in mice. Transient bradycardia and decrease of blood pressure are the most noticeable cardiovascular effects in dogs. This compound administered at 80–100 mg/m²/week in 1-h intravenous (IV) infusion induces objective remissions in about 25% of patients suffering from advanced breast cancer refractory to all other treatment. These remissions, which occurred after 3–4 weeks, lasted for 1–18 months. This drug seems particularly to improve the condition of patients suffering from oesteolytic breast cancer metastasis. Activity against anaplastic thyroid carcinoma and ovarian carcinoma has also been observed in some cases. Toxic side effects are nausea and vomiting (one-third of the patients), hypertension (less than 10% of the patients), muscular cramp (one-third of the patients), fatigue which can be very pronounced (in most patients after 3 months of treatment), mouth dryness, and mycosis of the tongue and esophagus (less than 20% of the patients).