The chemotherapeutic effects and complications of actinomycin D in patients with advanced cancer

Chemical basis of the synergism and antagonism in microbial communities in the nests of leaf-cutting ants

Leaf-cutting ants cultivate the fungus Leucoagaricus gongylophorus, which serves as a major food source. This symbiosis is threatened by microbial pathogens that can severely infect L. gongylophorus. Microbial symbionts of leaf-cutting ants, mainly Pseudonocardia and Streptomyces, support the ants in defending their fungus gardens against infections by supplying antimicrobial and antifungal compounds. The ecological role of microorganisms in the nests of leaf-cutting ants can only be addressed in detail if their secondary metabolites are known. Here, we use an approach for the rapid identification of established bioactive compounds from microorganisms in ecological contexts by combining phylogenetic data, database searches, and liquid chromatography electrospray ionisation high resolution mass spectrometry (LC-ESI-HR-MS) screening. Antimycins A(1)-A(4), valinomycins, and actinomycins were identified in this manner from Streptomyces symbionts of leaf-cutting ants. Matrix-assisted laser desorption ionization (MALDI) imaging revealed the distribution of valinomycin directly on the integument of Acromyrmex echinatior workers. Valinomycins and actinomycins were also directly identified in samples from the waste of A. echinatior and A. niger leaf-cutting ants, suggesting that the compounds exert their antimicrobial and antifungal potential in the nests of leaf-cutting ants. Strong synergistic effects of the secondary meta-bolites produced by ant-associated Streptomyces were observed in the agar diffusion assay against Escovopsis weberi. Actinomycins strongly inhibit soil bacteria as well as other Streptomyces and Pseudonocardia symbionts. The antifungal antimycins are not only active against pathogenic fungi but also the garden fungus L. gongylophorus itself. In conclusion, secondary metabolites of microbial symbionts of leaf-cutting ants contribute to shaping the microbial communities within the nests of leaf-cutting ants.

Unusual cutaneous toxicity following treatment with dactinomycin: a report of two cases

Dactinomycin-induced cutaneous toxicity is rare in pediatric patients not receiving radiation therapy. We describe dactinomycin-related lesions in the axilla, groin, and central line exit site of two children treated for rhabdomyosarcoma, neither of whom had received radiation treatment. One patient was initially treated with systemic antifungal therapy, and developed recurrent lesions on reexposure to the drug. The other was noted to have mild, diffuse hyperpigmentation. Skin biopsies revealed interface dermatitis with syringometaplasia in both cases. Both children recovered uneventfully within 4 weeks. Recognition of unusual rashes with a characteristic distribution in patients receiving dactinomycin should aid in diagnosis, and help avoid unnecessary therapeutic procedures.

Extravasation injury potential of CI-980, a novel synthetic mitotic inhibitor

Severe soft-tissue ulceration is known to result from inadvertent extravasation of a number of anticancer drugs, including tubulin-binding vinca alkaloids, during intravenous administration. CI-980 is a novel anticancer drug candidate that also inhibits mitosis by binding to tubulin. Intradermal administration of CI-980 to mice at doses of 0.02 and 0.05 mg produced ulcerative lesions in 3/5 and 2/5 animals, respectively, that were significantly smaller than those produced in all animals at vinblastine doses of 0.05 and 0.1 mg. Ulcerative lesions resulting from CI-980 treatment were also less persistent, resolving in 2-8 days versus 7-16 days following vinblastine administration. As based on the common dose of 0.05 mg, CI-980 appears to have significantly less vesicant activity than vinblastine.

Dose-dependent skin ulcers in mice treated with DNA binding antitumor antibiotics

The DNA-binding agents daunomycin (DAU-NO), mithramycin (MITH), dactinomycin (ACT-D), amsacrine (mAMSA) and esorubicin (ESO) were tested for local vesicant potential in a quantitative intradermal mouse skin model. Only MITH, which adlineates but doses not intercalate DNA, did not produce dose-dependent skin ulcerations in the mouse. The anthracycline antibiotics DAUNO and ESO produced the largest skin ulcers when administered intradermally at clinically relevant doses (adjusted on the basis of comparable body surface areas). Numerous local pharmacologic adjuvants were tested for activity to decrease skin ulceration patterns in mice given one of the DNA intercalators. Inactive local adjuvants included heat, cold, saline, hyaluronidase, glucorticosteroids and isoproternol. Only one adjuvant, topical dimethylsulfoxide (DMSO), was found to reduce DAUNO skin lesions. A single topical DMSO application significantly decreased ulceration size to almost half of control levels. However, it was ineffective for the other intercalating agents. These results show that the DNA intercalators DAUNO, ESO and ACT-D are potent vesicants in a mammalian skin model. These vesicant agents must be administered cautiously to prevent extravasation. No single local adjuvant treatment can be recommended for extravasation of these drugs in the clinic. One significant exception is DAUNO, where topical DMSO may reduce clinical toxicities.