Phase II study of a new alkylating agent (PTT-119) in resistant-relapsed non-Hodgkin's lymphomas

A novel transport and delivery mechanism underpins the effectiveness of prolyl-m-sarcolysyl-p-fluorophenylalanine (PSF) in a human melanoma xenograft nude-mouse model

The alkylating peptide PSF shows very promising results in vitro on different cancer cells but its efficacy in animals has not been assessed. Here we evaluate the efficacy of PSF in human melanoma-bearing nude mice and examine the underlying mechanism. In melanoma-bearing nude mice, escalating doses of PSF showed dose-dependent responses and reached tumor regression with an optimal dose of 20 mg/kg for 1 month. A comparison of PSF with its free moiety m-sarcolysin and melphalan showed a highly significant advantage of PSF. Furthermore, dose fractionation yielded an even better control of tumor regrowth. In vitro studies unraveled an original delivery mechanism based on the rapid binding of PSF mainly due to red blood cells to form a pro-drug complex and the subsequent release of active metabolites by tumor-associated proteolytic enzymes. Blood kinetics showed one major metabolite partially released over time, while in the presence of melanoma cells three additional metabolites are generated. Interestingly, tumor-shed proteases also induce the production of these metabolites and varying combinations of enzyme inhibitors indicate the involvement of metallo- and other families of proteases in the delivery process. This particular transport and delivery of such an alkylating agent may have several benefits, mainly lowering the drug-free moiety in plasma and at the same time increasing its concentration in protease rich areas such as tumors.

Ambamustine in the second-line treatment of patients with small-cell lung cancer: a phase II Fonicap study

Despite a high probability of response to first-line chemotherapy, most patients with small-cell lung cancer (SCLC) will eventually have progression of their disease because of the development of resistant disease. Second-line testing of new drugs is an accepted research strategy in SCLC. In this context, the Italian Lung Cancer Task Force (FONICAP) has tested a new synthetic bifunctional alkylating agent, Ambamustine, with preliminary evidence of activity in other solid tumors. Patients with measurable SCLC, progressive after one first-line chemotherapy regimen (either "sensitive" or "refractory"), were eligible for the study. Ambamustine was administered at the dose of 2 mg/kg as a 1-hour intravenous infusion on day 1 every 21 days. The dose was to be increased to 3 mg/kg if no grade IV toxicity and complete hematologic recovery had occurred by day 22. Sample size was calculated according to a two-stage optimal Simon's design. Seventeen patients were entered into the study. Twelve patients were refractory to prior chemotherapy; 12 had extensive disease; the median age was 64 years (range: 46-75 years) and the median performance status was 1. Among 13 patients who received more than one cycle, 9 patients could increase Ambamustine dose from 2 to 3 mg/kg. No objective response was observed: one patient obtained a 50% regression of the primary tumor with contemporary disease progression in the liver and was qualified as having progressive disease. The treatment was well tolerated: grade IV leukopenia occurred in only 1 patient; grade III anemia occurred in 17.6%, grade III leukopenia in 11.8%, and grade III thrombocytopenia in 23.5%. Nonhematologic toxicity was minimal. Ambamustine, at the dose and schedule used in this study, is well tolerated in pretreated patients with SCLC but has no significant antitumor activity in this unfavorable group of patients.

Autotransplants in advanced non-Hodgkin lymphoma: are they effective?

Recent data suggest that intensive therapy followed by a bone marrow autotransplant is effective in advanced intermediate and high-grade non-Hodgkin lymphoma (predominantly large-cell lymphoma). Twelve studies of autotransplants were analyzed to determine outcome. Results compared to data from 29 chemotherapy studies. Complete remission was reported in 53% of autotransplant recipients versus 17% of persons receiving chemotherapy. Two-year disease-free survival was 16 and 2%, respectively. It is uncertain whether these differences indicate superiority of autotransplants or reflect selection biases. Also unknown is whether similar results might not be obtained with similarly intensive treatment without an autotransplant.

Evidence for increased intracellular transport of m-sarcolysine (alkylating moiety) when combined with two amino acid analogs (PTT-119)

PTT-119 is an antineoplastic agent in which an alkylating moiety, m-sarcolysine, is linked to two amino acid analogs. Previous studies showed a higher "in vitro" cytotoxicity of PTT-119 when compared to free m-sarcolysine; the mechanisms of this enhanced activity are not completely understood. In this study we incubated peripheral blood cells from 8 chronic lymphocytic leukemia patients with both m-sarcolysine and equimolar concentrations of PTT-119, measuring the intracellular concentration of the alkylating moiety. We observed a significantly higher intracellular concentration of m-sarcolysine in cells incubated with the peptide-bound drug than with the free drug (58.3 +/- 39.6 versus 4.4 +/- 1.9 ng/10(6) cells; P = 0.013). This observation could explain the higher cytotoxic activity of PTT-119 and the lack of cross-resistance with melphalan.

Phase II cooperative study with a new alkylating drug, PTT-119, in the treatment of non-Hodgkin's lymphomas

In a phase II cooperative study involving eleven Italian haematological units, the efficacy and toxicity of a new alkylating compound, PTT-119, was evaluated in 53 patients with non-Hodgkin's lymphoma (NHL). Forty-five of the patients had been previously treated with various regimens of chemotherapy, the remaining eight were at the onset of the disease. PTT-119 was scheduled at 3.0 mg/kg every three weeks for a minimum of three administrations. Seven patients achieved a complete remission (CR), 19 a partial remission (PR); the overall response rate was 49%. The median duration of response was 6 months. Most frequent adverse effects were alopecia, nausea and vomiting and phlebitis due to the drug infusion. Myelosuppression was severe only in patients with bone marrow involvement or who were heavily pretreated. No liver, cardiac or renal toxicity was recorded. These data indicate that PTT-119 is an effective drug in the treatment of NHL; the matter of its non-cross-resistance with other alkylating compounds warrants further studies.