Rubeomycin A

We summarize here the antitumor activity of newly developed drugs against malignant lymphoma. Irinotecan hydrochloride (CPT-11) showed a CR rate of 15% and an excellent response (CR + PR) rate of 42% in patients with non-Hodgkin's lymphoma who had prior treatment. In patients with ATL, 13% achieved CR and a response rate was 39%. MST-16, a new orally administered bis(2, 6-dioxopiperazine) analogue, showed a CR of 3% and PR of 28% (response rate 31%), among patients with ATL, 9% of 23 patients achieved CR and the response rate was 44%. Phase I studies of fludarabine demonstrated a high response rate of 64%, especially in follicular lymphoma, with a number of patients achieving CR. Subsequent phase II studies demonstrated a response rate of 89% in patients with indolent lymphoma. KRN 8602 was developed in an attempt to improve the clinical efficacy of currently used anthracyclines. KRN 8602 has been shown to produce less cardiotoxicity and alopecia, yet has comparable antitumor effects to ADM, and also has demonstrated an antitumor effect on ADM-resistant tumors. CPT-11 and MST-16 were found effective not only in refractory non-Hodgkin's lymphoma, but also in patients with ATL, which had no standard therapy. Fludarabine has been demonstrated to be a very active drug in indolent lymphoid neoplasms, particularly CLL and low grade lymphoma. These new drugs are expected to overcome malignant lymphoma refractory to treatment thus far.

KRN8602(MX2) is a newly developed morpholino-anthracycline that has been found to cross the blood-brain barrier and be distributed in brain tissue after intravenous administration and to be effective against human glioma cells and the intracerebrally transplanted tumors in vivo. In order to confirm these promising preclinical observations clinically, we performed a phase II trial of KRN8602 in patients with recurrent malignant glioma. The 44 patients enrolled received at least 2 cycles of KRN8602 35 mg/m2/day at 3-4 week intervals by intravenous bolus. Of the 44 patients, 37 could be evaluated for response, and 39 for toxicity. One patient with anaplastic astrocytoma had a complete response (1/37, 3%), and 2 patients with anaplastic astrocytoma and 1 with brain stem glioma had a partial response (3/37, 8%). The overall response rate was 11% (4/37). All patients who responded had received prior chemotherapy that included nitrosoureas. No response was observed in the patients with glioblastoma. Myelosuppression was moderately severe, with 72% of patients developing grade 3 or 4 leukopenia. Severe nausea/vomiting was observed in 31% of the patients. No severe cardiotoxicity was observed. The results indicate that KRN8602 has modest activity against recurrent malignant glioma with relatively severe, but manageable toxicity. It seems to be worthwhile to further assess the efficacy and toxicity of KRN8602 against malignant glioma, which is generally less sensitive to chemotherapy.

Doxorubicin is an essential component of the treatment of aggressive lymphoma, childhood solid tumors, bone and soft tissue sarcomas, and breast cancer and additional indications are emerging. On the other hand, daunorubicin has occupied the central position of interest in the treatment of acute leukemia. Epirubicin has a spectrum very similar to doxorubicin but lesser toxicity. The ability to protect against cardiotoxicity with ICRF-187 further enhances clinical interest in exploiting modifications in doze intensity to therapeutic advantage. Idarubicin has at least equivalent activity to daunorubicin and doxorubicin in leukemia. New areas of research in relation to anthracycline antibiotics include introduction of new the analogs, insight into mechanisms of resistance, the reversal of multidrug resistance in vitro, the protection of cardiac toxicity, and the study of other important biochemical reactions relevant to cytotoxicity. Orally active anthracyclines such as idarubicin and compounds which lack cross-resistance with the parent drugs or have other mechanisms for cytotoxicity are being developed. It is likely that these modifications will lead to an expanding therapeutic spectrum for these already widely useful drugs.