Pharmacokinetics of melphalan in isolated limb perfusion

The pharmacokinetics of melphalan was studied by sampling of tissue and plasma in 72 rats that␣underwent isolated hyperthermic limb perfusion under different conditions. A miniaturized extracorporeal circulation system for small animals was used for␣perfusion of the rat hindlimb. Melphalan levels (l-phenylalanine mustard, L-PAM) were determined by high-performance liquid chromatography (HPLC). The temperature of the perfusate plasma and tissue, pH, administration method, and flow rate were modified and compared with regard to their influence on pharmacokinetic parameters. The highest tissue penetration of melphalan was observed under the following conditions: (a) pH range of the perfusate plasma between 7.3 and 7.7 (physiological environment), (b) temperature range of the perfusate from 40° to 41.5 °C (destruction of cellular carrier systems at higher temperatures and increased inactivation by hydrolysis of melphalan above 41.5 °C), (c) application of melphalan as a single dose into the reservoir of the extracorporeal circuit (optimal tissue penetration), and (d) reduced perfusate flow (prolonged contact time between perfusate and tissue). Received: 23 February 1998 / Accepted: 2 June 1998     

Clinical perspectives for the use of new hypoxic cell sensitizers

Experience with high pressure oxygen in combination with radiotherapy has shown that, for some tumors at least, the presence of hypoxic cells is a limiting factor in the ability to cure these tumors even with conventional daily fractionation. This suggests that hypoxic cell radiosensitizers, of which misonidazole (MISO) is the prototype drug, may play a role in improving the cure-rate of some tumors when combined with daily fractionation. Even for those tumors for which no improvement is seen when combined with daily fractionation, it is likely that there will be an important role for these sensitizers by using them in combination with regimens of only a few dose fractions. Because of the limiting side effects of neuropathy, a less toxic radiosensitizer than MISO is required to gain the full clinical benefit of these drugs. A possible way of achieving this is to reduce the lipid solubility (lipophilicity) of the compounds while still retaining their electron-affinity. This reduces the concentration of drug in the neural tissues (brain, peripheral nerves) without affecting the tumor concentration. However, if the lipophilicity is too low, the drugs are unable to enter the hypoxic cells and hence lose their radiosensitizing efficiency. It would appear that a lipophilicity given by an octanol:water partition coefficient of approximately 0.04 is optimum (cf. MISO = 0.43) with the 2-nitroimidazole amide SR-2508 the best in this series. Tumor levels of this drug of at least 7–8 times those obtained with MISO should be attainable clinically for no increase in neurotoxicity. Another property of electron-affinic sensitizers shows clinical promise. This is their ability to preferentially sensitize tumors compared to normal tissues to the cytotoxic action of several chemotherapeutic agents. A therapeutic gain of a factor of approximately 2 can be obtained when cyclophosphamide or melphalan is combined with MISO at dose levels that can be achieved clinically.     

Bivalent bendamustine and melphalan derivatives as anticancer agents

The alkylating agents bendamustine and melphalan are currently used in the treatment of various tumoral diseases. In order to increase their antitumor potency and tumor selectivity both compounds were integrated in structure-activity relationship studies including new drug carrier systems. Here we describe the synthesis and the cytotoxicity of new bivalent bendamustine and melphalan derivatives. Two molecules each esterified with N-(2-hydroxyethyl)maleimide were connected by diamines with various chain lengths (n = 6, 7, 8, 12). It was supposed that these conjugates (5a-d, 10a-d, 11a-d) cause cytotoxic effects preferred as bivalent drug. Indeed the cytotoxicity of the new compounds increased compared to bendamustine and melphalan as determined in concentration-dependent in vitro assays using the human MCF-7 and MDA-MB-231 breast cancer cell lines.     

Possible Benefits of High-Dose Chemotherapy as Intensive Consolidation in Patients with High-Risk Rhabdomyosarcoma Who Achieve Complete Remission with Conventional Chemotherapy

The authors reviewed their single-center experience with autologous stem cell transplantation (SCT) in 22 patients with advanced rhabdomyosarcoma. Pathological subtypes included alveolar ( n = 7) and embryonal types ( n = 15). The conditioning regimen primarily consisted of etoposide, carboplatin, and melphalan. Fourteen, five, and three patients underwent SCT in CR, PR, and PD, respectively. Eight patients are currently alive without evidence of disease. The overall survival rate at 5 years was 70% for 14 patients who were in CR at the time of SCT. This limited experience warrants the examination of SCT in a prospective study.     

Marked variability of melphalan plasma drug levels during regional hyperthermic isolated limb perfusion

BACKGROUND: Hyperthermic isolated limb perfusion (HILP) with melphalan as treatment for locally recurrent or in-transit malignant melanoma is frequently performed but the principle for calculating drug dosage remains poorly understood. METHODS: This study examined the pharmacokinetic profile of 14 consecutive patients to determine what variables were associated with toxicity and tumor responses. RESULTS: Marked fourfold variability was noted in patient plasma melphalan concentrations. We defined a factor--the ratio of estimated limb volume (Vesti) to melphalan volume of distribution (Vss), Vesti/Vss--that was much more strongly correlated with acute regional toxicity than either area under concentration-time curve or peak plasma concentration. In addition, we found that AUX2 was the best correlate of tumor response. CONCLUSIONS: Pharmacokinetic evaluation of prospective HILP trials is critical to not only understand response and toxicity outcomes but also to potentially improve the therapeutic index of regional perfusion.     

Possible benefits of high-dose chemotherapy as intensive consolidation in patients with high-risk rhabdomyosarcoma who achieve complete remission with conventional chemotherapy

The authors reviewed their single-center experience with autologous stem cell transplantation (SCT) in 22 patients with advanced rhabdomyosarcoma. Pathological subtypes included alveolar ( n = 7) and embryonal types ( n = 15). The conditioning regimen primarily consisted of etoposide, carboplatin, and melphalan. Fourteen, five, and three patients underwent SCT in CR, PR, and PD, respectively. Eight patients are currently alive without evidence of disease. The overall survival rate at 5 years was 70% for 14 patients who were in CR at the time of SCT. This limited experience warrants the examination of SCT in a prospective study.     

Isolated Hypoxic Hepatic Perfusion With Orthograde or Retrograde Flow in Patients With Irresectable Liver Metastases Using Percutaneous Balloon Catheter Techniques: A Phase I and II Study

Background Isolated hepatic perfusion for irresectable metastases confined to the liver has reported response rates of 50% to 75%. Magnitude, costs, and nonrepeatability of the procedure are its major drawbacks. We developed a less invasive, less costly, and potentially repeatable balloon catheter–mediated isolated hypoxic hepatic perfusion (IHHP) technique.Methods In this phase I and II study, 18 consecutive patients with irresectable colorectal or ocular melanoma hepatic metastases were included. Two different perfusion methods were used, both with inflow via the hepatic artery, using melphalan 1 mg/kg. In the first eight patients, the portal vein was occluded, and outflow was via the hepatic veins into an intracaval double-balloon catheter. This orthograde IHHP had on average 56% leakage. In next 10 patients, we performed a retrograde outflow IHHP with a triple balloon blocking outflow into the caval vein and allowing outflow via the portal vein. The retrograde IHHP still had 35% leakage on average.Results Although local drug concentrations were high with retrograde IHHP, systemic toxicity was still moderate to severe. Partial responses were seen in 12% and stable disease in 81% of patients. The median time to local progression was 4.8 months.Conclusions We have abandoned occlusion balloon methodology for IHHP because it failed to obtain leakage control. We are presently conducting a study using a simplified surgical retrograde IHHP method, in which leakage is fully controlled, which translates into high response rates.     

Temozolomide is a novel regional infusion agent for the treatment of advanced extremity melanoma

BACKGROUND: Regional infusion therapy with melphalan (LPAM) is an accepted treatment for advanced extremity melanoma. However, much room exists for improving the therapeutic index of this type of therapy. METHODS: Isolated limb infusion (ILI) with temozolomide (TMZ), a novel methylating agent, was performed using a nude rat bearing human melanoma xenograft. Additional rats were treated systemically with TMZ, or regionally with LPAM or 10% dimethyl sulfoxide (DMSO; control) using ILI. RESULTS: Rats that received systemic TMZ showed a poor tumor response and no tumor regression. In contrast, intra-arterial TMZ demonstrated a prolongation of tumor growth delay in a dose-responsive manner. In comparison with LPAM of equitoxic dose, TMZ provided both longer tumor growth delay and a greater number of tumor regressions. CONCLUSIONS: These data suggest that ILI with TMZ is an effective treatment for advanced extremity melanoma and may be better than LPAM in this setting.     

Deliberate hypoxic pelvic and limb chemoperfusion in the treatment of recurrent melanoma

BACKGROUND: The treatment of patients with advanced or recurrent pelvic melanoma, which are often associated with lesions in the lower limbs, is still unsatisfactory and controversial. A simplified hypoxic pelvic and limb perfusion has been recently recommended to provide therapeutic options for palliation and possibly cure. METHODS: A nonrandomized and noncontrolled phase II experimental study was performed in 11 patients with symptomatic unresectable recurrent melanoma of the pelvis and limb. Patients were submitted to hypoxic pelvic and limb perfusion with 25 mg/m(2) of melphalan, 50 mg/m(2) of cisplatin, 300 mg/m(2) of dacarbazine, and 75 mg/m(2) of epirubicin by means of a simplified balloon occlusion technique. Response rate and time to disease progression were the primary endpoints; overall survival was the secondary endpoint. RESULTS: During the procedures there were no technical, hemodynamic, or vascular complications, and no deaths occurred during surgery or in the postoperative period. Response rate was 82% (95% confidence interval, 58% to 100%). Median time to disease progression was 12 months (range 9 to 30 months). Three-year overall survival was 34%. CONCLUSIONS: Hypoxic pelvic and limb perfusion is a safe and good palliative treatment for patients with unresectable recurrent melanoma. Further studies are necessary to to confirm these data and to establish if refinements can be made with acceptable toxicity.