Peptichemio, Vincristine, Prednisone Induction Treatment in Multiple Myeloma

Activity of hydrolytic enzymes in tumour cells is a determinant for anti-tumour efficacy of the melphalan containing prodrug J1

Recently, we presented a series of melphalan containing di- and tripeptides with high cytotoxic activity and J1 (l-melphalanyl-p-l-fluorophenylalanine ethyl ester) was identified as one of the most interesting compounds. It was speculated that the increased activity compared to melphalan itself, demonstrated both in vitro and in vivo, resided in increased transport over the tumour cell membrane and/or hydrolytic cleavage and liberation of melphalan inside the cells. Indeed, overexpression of hydrolytic enzymes like peptidases, esterases and proteases has been described in several types of human malignancies, thus providing a target for selective chemotherapy. In this work, the details of the increased activity was further investigated and potential tumour selectivity is discussed. The intracellular delivery of melphalan is investigated in detail using peptidase resistant dipeptide derivatives, by enzyme inhibitors and probes for enzymatic activity and by studying the time dependency of drug effect as well as intracellular drug concentrations (cellular pharmacokinetics). The results show that the activity of the dipeptide mustards is highly dependent on intracellular hydrolysis, which result in rapid intracellular release of the alkylating unit (i.e. free melphalan) in cells with high enzymatic activity. The maximum intracellular melphalan concentration following J1 exposure was reached already after 15 min, thereafter declining with a half-life of approximately 1 h. This rapid intracellular loading resulted in less reduction of activity for J1 than for melphalan and six other standard drugs when human tumour cell lines were exposed to the drugs for a limited time (simulating short half-life in vivo). Peptidase inhibitors inhibited the activity and intracellular release of melphalan, and dipeptide derivatives designed to resist the action of peptidases was less active than the corresponding normal dipeptide.

Pharmacokinetics of peptichemio in myeloma patients: release of m-L-sarcolysin in vivo and in vitro

Peptichemio (PTC) is a mixture of six synthetic oligopeptides, each of which contains the alkylating residue m-[di(2-chloroethyl)amino]-L-phenylalanine (L-mSL). The fate of PTC was investigated in eight patients with multiple myeloma after intravenous infusion of the drug. The quantitative analysis of the plasma samples was performed by liquid chromatography with fluorometric detection. L-mSL was rapidly released from the peptides and reached its maximal plasma concentration at the end of the infusion. Its median elimination half-life was 1.73 (range, 0.72-2.41) h. It was possible to follow the concentration of only one of the peptides, L-mSL-L-Arg(NO2)-L-Nval.OEt, during and shortly after the infusion of PTC. The stability of L-mSL and the peptides was studied in buffer solution (pH 7.3), plasma, and blood. The stability of some of the peptides was drastically decreased in blood, the degradation half-lives being only about 1 min. We conclude that L-mSL plays an important role in the mechanism of action of PTC.

Peptichemio, vincristine and prednisone versus melphalan and prednisone as induction therapy in multiple myeloma

Seventy-five patients with previously untreated multiple myeloma were randomly treated with the association of Peptichemio, Vincristine and prednisone (PTC-VCR-P) or of melphalan and P (MPH-P) for first induction therapy. After induction, all responsive patients received MPH and P until relapse, while unresponsive patients received it until unequivocal evidence of disease progression was observed. A second induction therapy with PTC-VCR-P was then administered, except to patients resistant to this association at first induction (who received combination chemotherapy which included cyclophosphamide and adriamycin). The response rate was 58% in the PTC-VCR-P and 41% in the MPH-P group (P greater than 0.05). The PTC-VCR-P responsive patients experienced a median duration of response shorter than MPH-P responsive patients (20.3 vs 39.7, P = 0.041). Median survival from the start of treatment was 26.2 months in the PTC-VCR-P and 54.1 months in the MPH-P group of patients (P = 0.039). Stage I and II myelomas had the same response rate to PTC-VCR-P and to MPH-P, but their survival was shorter on PTC-VCR-P than on MPH-P (P = 0.014). Stage III myelomas responded more frequently to PTC-VCR-P than to MPH-P (P less than 0.02) and there was a trend to survive longer on PTC-VCR-P than on MPH-P (22.0 vs 12.5 months, P greater than 0.05).