High Intratumoral Accumulation of Stealth Liposomal Doxorubicin in Sarcomas: Rationale for Combination with Radiotherapy

The aim of this trial was to compare the activity and toxicity of single-agent doxorubicin with that of two multidrug regimens in the treatment of patients with adult advanced soft tissue sarcomas. This was a prospective randomized phase III trial performed by 35 cancer centers within the Soft Tissue and Bone Sarcoma Group of the European Organization for Research and Treatment of Cancer (EORTC). Six hundred sixty-three eligible patients were randomly allocated to receive either doxorubicin 75 mg/m2 (arm A), cyclophosphamide, vincristine, doxorubicin, and dacarbazine (CYVADIC) (arm B), or ifosfamide 5 g/m2 plus doxorubicin 50 mg/m2 (arm C). The overall response rate was 24% (95% confidence interval, 20.7% to 27.3%) among eligible patients and 26% among assessable patients. No statistically significant difference was detected among the three study arms in terms of response rate (arm A, 23.3%; arm B, 28.4%; and arm C, 28.1%), remission duration (median, 46 weeks on arm A, 48 weeks on arm B, and 44 weeks on arm C), or overall survival (median, 52 weeks on arm A, 51 weeks on arm B, and 55 weeks on arm C). The degree of myelosuppression was significantly greater for the combination of ifosfamide and doxorubicin than for the other two regimens. Cardiotoxicity was also more frequent in this arm, but other toxicities were similar. In advanced soft tissue sarcomas of adults, single-agent doxorubicin is still the standard chemotherapy against which more intensive or new drug treatments should be compared. Combination chemotherapy cannot be recommended outside a controlled clinical trial with the exclusion of some subsets of sarcoma patients for whom significant tumor volume reduction may be an important end point of a chemotherapy regimen. Show more

This three-armed phase III study in adults with advanced soft tissue sarcomas was planned as a comparison of objective regression rates, toxicity, and survival of patients receiving doxorubicin alone, ifosfamide plus doxorubicin, and mitomycin plus doxorubicin plus cisplatin. Between December 1987 and July 1990, 279 patients with histologically confirmed sarcomas were enrolled to receive treatment A (doxorubicin 80 mg/m2), treatment B (ifosfamide 7.5 g/m2 plus doxorubicin 60 mg/m2), or treatment C (mitomycin 8 mg/m2 plus doxorubicin 40 mg/m2 plus cisplatin 60 mg/m2). Of 262 assessable patients, 74 (29%) achieved objective tumor regression. Objective regression occurred in 20% of the 90 patients who received doxorubicin alone (complete remission [CR] rate, 2%), in 34% of the 88 who received ifosfamide plus doxorubicin (CR rate, 3%), and in 32% of the 84 who received mitomycin plus doxorubicin plus cisplatin (CR rate, 7%). With grade 3 or greater myelosuppression in 53% of group A, 80% of group B, and 55% of group C, regimen B was significantly more myelosuppressive than either regimen A or C (P = .01) with two, three, and one treatment-related deaths, respectively. Synovial sarcomas were responsive to ifosfamide plus doxorubicin, especially among patients younger than 40 years of age. Ifosfamide plus doxorubicin produced a significantly higher regression rate (P = .03) than did doxorubicin alone; however, this was achieved at a level of myelosuppression significantly more intense than that produced by the single agent or by the three-drug combination. Mitomycin, doxorubicin, and cisplatin also appeared to be more active than the single agent; however, at a myelosuppression level similar to that of doxorubicin alone, this trend (P = .07) did not attain the usual level for significance. No significant survival differences were observed. Show more

Therapeutic applications of intravenously injected liposomes have been limited by their rapid clearance from the bloodstream and their uptake by the macrophage cells of the liver and spleen (RES). Recently, however, liposomes which substantially evade the rapid uptake by the RES have been introduced. Since these liposomes exhibit dramatically different pharmacokinetics and biodistribution, new therapeutic opportunities have appeared. These include enhanced efficacy of antineoplastic agents against tumors, sites of inflammation, and targeting ligand-coupled liposomes to extravascular targets. Despite extensive experimental work, the mechanism underlying the ability of liposomes to avoid the rapid uptake by the RES is still not fully understood. Our approach is an alternative to seeking the answers in complex differential interactions of liposomes with various components of blood. We believe that the effect can be easily explained, at least in qualitative terms, by the fundamental principles of colloid stability. In this communication, we propose that steric stabilization of liposomes is responsible for their prolonged circulation times. We propose that stabilization results from local surface concentration of highly hydrated groups that sterically inhibit both electrostatic and hydrophobic interactions of a variety of blood components at the liposome surface. Show more