Purpose: To determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetic characteristics of doxorubicin encapsulated in a low temperature sensitive liposome (LTSL) when given concurrently with local hyperthermia to canine solid tumors. Experimental Design: Privately owned dogs with solid tumors (carcinomas or sarcomas) were treated. The tumors did not involve bone and were located at sites amenable to local hyperthermia. LTSL-doxorubicin was given (0.7-1.0 mg/kg i.v.) over 30 minutes during local tumor hyperthermia in a standard phase I dose escalation study. Three treatments, given 3 weeks apart, were scheduled. Toxicity was monitored for an additional month. Pharmacokinetics were evaluated during the first treatment cycle. Results: Twenty-one patients were enrolled: 18 with sarcomas and 3 with carcinomas. Grade 4 neutropenia and acute death secondary to liver failure, possibly drug related, were the doselimiting toxicities. The maximum tolerated dose was 0.93 mg/kg. Other toxicities, with the possible exception of renal damage, were consistent with those observed following free doxorubicin administration. Of the 20 dogs that received z2 doses of LTSL-doxorubicin, 12 had stable disease, and 6 had a partial response to treatment. Pharmacokinetic variables were more similar to those of free doxorubicin than the marketed liposomal product. Tumor drug concentrations at a dose of 1.0 mg/kg averaged 9.12 F 6.17 ng/mg tissue. Conclusion: LTSL-doxorubicin offers a novel approach to improving drug delivery to solid tumors. It was well tolerated and resulted in favorable response profiles in these patients. Additional evaluation in human patients is warranted.Liposome-encapsulated chemotherapy was developed to improve selectivity of drug for tumor compared with normal tissue. Despite the achievement of tumor drug levels that are up to 10-fold higher than those achieved with unencapsulated drugs, particularly when given concurrently with hyperthermia, clinical efficacy of these agents has been only modestly improved (1 -4). Decreased toxicity, in particular the cardiotoxicity seen with doxorubicin, has been the most significant benefit derived from these formulations.One potential explanation for the lack of clinical benefit from liposomal drug delivery to the tumor tissue is the dependence of cytotoxicity on the presence of free drug. Although the liposomes may accumulate preferentially in tumors, the mechanisms by which traditional liposomes release their contents are not well understood (5). The development of liposomes engineered for triggered drug release is one approach that addresses this problem directly.The development of hyperthermia-mediated drug release from liposomes was first reported in 1978 (6). These early thermosensitive liposomes typically released their contents at temperatures > 42jC. Temperatures in this range are difficult to achieve uniformly in a clinical setting. In addition, drug release was slow, requiring 30 minutes to release 40% of the contents (7). Because of...

Background: Peripheral blood CD34+ hematopoietic cell transplantation (PBHCT) is commonly used to treat human patients with relapsed non-Hodgkin diffuse, large B-cell lymphoma with cure rates approaching 50%.Objective: To determine the safety and feasibility of performing PBHCT to treat canine B-cell lymphoma (LSA) patients in a clinical academic setting.Animals: Twenty-four client-owned dogs diagnosed with B-cell LSA. Methods: After high-dose cyclophosphamide and rhG-colony-stimulating factor treatment, peripheral blood mononuclear cells were collected using cell separator machines. The harvested cells then were infused after a 10 Gy dose of total body irradiation (TBI). Post-irradiation adverse effects were managed symptomatically and dogs were discharged upon evidence of engraftment.Results: More than 2 9 10 6 CD34+ cells/kg were harvested in 23/24 dogs. Preapheresis peripheral blood monocyte count was correlated with the number of CD34+ cells/kg harvested. Twenty-one of 24 (87.5%) dogs engrafted appropriately, whereas 2 dogs (8.3%) died in the hospital. One (5%) dog exhibited delayed engraftment and died 45 days after PBHCT. One dog developed presumed TBI-induced pulmonary fibrosis approximately 8 months after PBHCT. The median disease-free interval and overall survival (OS) of all dogs from the time of PBHCT was 271 and 463 days, respectively. Five of 15 (33%) dogs transplanted before they relapsed remain in clinical remission for their disease at a median OS of 524 days (range, 361-665 days).Conclusions and Clinical Importance: In most cases, PBHCT led to complete hematologic reconstitution. Therefore, PBHCT may be considered as a treatment option for dogs with B-cell lymphoma.

Purpose:To test that prospective delivery of higher thermal dose is associated with longer tumor control duration. Experimental Design: 122 dogs with a heatable soft tissue sarcoma were randomized to receive a low (2-5 CEM43jCT90) or high (20-50 CEM43jCT90) thermal dose in combination with radiotherapy. Most dogs (90%) received four to six hyperthermia treatments over 5 weeks. Results: In the primary analysis, median (95% confidence interval) duration of local control in the low-dose group was1.2 (0.7-2.1) years versus1.9 (1.4-3.2) years in the high-dose group (log-rank P = 0.28). The probability (95% confidence interval) of tumor control at 1 year in the low-dose versus high-dose groups was 0.57 (0.43-0.70) versus 0.74 (0.62-0.86), respectively. Using multivariable procedure, thermal dose group (P = 0.023), total duration of heating (P = 0.008), tumor volume (P = 0.041), and tumor grade (P = 0.027) were significantly related to duration of local tumor control. When correcting for volume, grade, and duration of heating, dogs in the low-dose group were 2.3 times as likely to experience local failure. Conclusions: Thermal dose is directly related to local control duration in irradiated canine sarcomas. Longer heating being associated with shorter local tumor control was unexpected. However, the effect of thermal dose on tumor control was stronger than for heating duration. The heating duration effect is possibly mediated through deleterious effects on tumor oxygenation. These results are the first to show the value of prospectively controlled thermal dose in achieving local tumor control with thermoradiotherapy, and they establish a paradigm for prescribing thermoradiotherapy and writing a thermal prescription.

Our objective was to further characterize the late normal tissue complications developing after definitive irradiation of pelvic region tumors in dogs, and to search for prognostic factors. The medical records of dogs receiving definitive irradiation of the pelvic region between 1987 and 2005 were reviewed. The following criteria were established for inclusion: total dose > or =45 Gy, a portion of colon in the primary field, and a minimum of 6 months follow-up. Fifty-one dogs were identified. Prognostic factors evaluated included multiple descriptors of the patient, tumor and radiation treatment. One or more late complications were documented in 20 of 51 patients (39%). Complications were necrotic drainage/ulceration in the skin and subcutaneous tissues within the radiation field (n=7), chronic colitis (n=4), strictures (n=4), osteopenia (n=2), and one each rectal perforation, urinary bladder thickening, iliosacral osteosarcoma, pelvic limb edema, and perianal pain. Two prognostic factors were identified. There was an increase in complications in dogs with perineal tumors compared with other pelvic region sites (P = 0.04), and also in dogs with larger radiation fields (P = 0.04). The finding of an association of tumor site to complications may be a spurious finding and the association between field size and complications is not unexpected although absolute difference in field size between dogs with and without complications was small. There was no association between development of complications and survival. Based on the observed complication rate, consideration can be given to reducing dose per fraction in dogs receiving definitive pelvic region irradiation to <3 Gy.

Tumour oxygenation was measured in seven canine soft tissue sarcomas being treated with a fractionated course of radiation and hyperthermia. Measurements obtained during treatment were compared to pre-treatment measurements. The most important finding was an increase in oxygenation in tumours with low pre-treatment oxygenation that persisted throughout treatment. This is an advantageous hyperthermia effect as it may lead to increased radiation cell killing at each fraction. In other tumours, potentially less advantageous changes in oxygenation may be hyperthermia fractionation related and this deserves further investigation.