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Brostallicin is a bromoacryloyl derivative of distamycin A, which has shown very promising preclinical activity against a variety of human tumors both in vitro and in vivo. The drug has a limited toxicity towards bone marrow precursor cells in vitro resulting in a therapeutic index much higher than those achieved with other distamycin A derivatives. It retains activity against cancer cells resistant to alkylating agents, topoisomerase I inhibitors and cells with mismatch repair deficiency. Brostallicin has a peculiar mechanism of action involving activation upon binding to glutathione (GSH) catalyzed by glutathione-S-transferase (GST). As a consequence, cells expressing relatively high GST/GSH levels are more susceptible to treatment with brostallicin. Considering that increased levels of GST/GSH are often found in human tumors, this could represent an advantage for the drug in the clinic. Initial clinical studies indicate the tolerability of the drug and allow the determination of the optimal dose for subsequent studies. Some partial response were obtained in these initial phase I studies. Altogether, the results suggest brostallicin to be a new promising anticancer agent with a new mechanism of action. It also raises the possibility to use it in combination with other anticancer drugs currently used.

PNU 145156E (formerly FCE 26644) is a noncytotoxic molecule whose antitumor activity is exerted through the formation of a reversible complex with growth/angiogenic factors, thus inhibiting their induction of angiogenesis. We studied in vitro and in vivo the activity of PNU145156E in combination with the four cytotoxic drugs doxorubicin, cyclophosphamide, methoxymorpholinyldoxorubicin (MMDX, FCE 23762, PNU152243), and 9-aminocamptothecin against M5076 murine reticulosarcoma. In vitro, PNU 145156E did not modify the cytotoxicity of the four drugs or the cell-cycle block induced by doxorubicin. In vivo, at the optimal dose of each compound, the antitumor activity was significantly increased in all combinations, with no associated increase in general toxicity being observed. In healthy mice treated with cyclophosphamide or doxorubicin the association with PNU 145156E did not enhance the myelotoxic effect induced by the two cytotoxics. These results indicate that two drugs affecting solid tumor growth through two different mechanisms-growth factor blockage and cell proliferation can be combined, resulting in increased antitumor efficacy with no additive toxicity.

The results suggest that PTX does not exacerbate the chronic cardiomyopathy caused by DOX and when added to the DOX + PTX combination, DZR retains its protective activity against DOX-induced cardiotoxicity without increasing noncardiac toxicity.

The results indicate that the pharmacologic effects of DZR, including its ability to protect against cardiotoxicity, are similar in immature and adult male animals treated with DOX.

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The novel cytotoxic antitumor derivative, PNU-159548, is significantly less cardiotoxic than doxorubicin at equimyelosuppressive doses. The combination of intercalating and alkylating activities within the same molecule without the cardiotoxic side effects of anthracyclines makes PNU-159548 an excellent candidate for clinical development in oncology.