Susan M. LaRue

Phase I Trial of Doxorubicin-Containing Low Temperature Sensitive Liposomes in Spontaneous Canine Tumors

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 dose-limiting 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 ≥2 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 ± 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.

Intra-arterial cisplatin with or without radiation in limb-sparing for canine osteosarcoma

Methods. Forty‐nine dogs with spontaneously occurring osteosarcoma underwent limb‐sparing surgery after preoperative therapy consisting of intra‐arterial cisplatin alone or intra‐arterial cisplatin in combination with doses of radiation from 20–40 Gy in 10 fractions. All resections were marginal, and the defect was repaired with a cortical allograft.

Thermal dose is related to duration of local control in canine sarcomas treated with thermoradiotherapy

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 CEM43°CT90) or high (20-50 CEM43°CT90) 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 was 1.2 (0.7-2.1) years versus 1.9 (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.

Multilobular Osteochondrosarcoma in 39 Dogs: 1979-1993

Thirty-nine, older, large-breed dogs with multilobular osteochondrosarcoma (MLO) each presented primarily with a fixed mass involving the flat bones of the skull. Twenty-five dogs were treated with surgical resection alone, nine were treated with adjuvant therapy, and five were not treated. Forty-seven percent of dogs treated had local tumor recurrence, and 56% had metastasis. Median time to recurrence, median time to metastasis, and median survival time were 797, 542, and 797 days, respectively. Histological grade, surgical margins, and tumor location affected outcome. Long-term remission can be obtained with aggressive treatment of MLO, although it is locally invasive and moderately metastatic.

Percent tumor necrosis as a predictor of treatment response in canine osteosarcoma

The percent tumor necrosis was determined in 200 dogs with spontaneously occurring osteosarcoma. One hundred dogs had no treatment before amputation or death. One hundred other dogs were treated with either radiation therapy alone (n = 23), intraarterial (IA) cisplatin alone (n = 16), intravenous (IV) cisplatin alone (n = 6), radiation therapy plus IA cisplatin (n = 47), or radiation therapy plus IV cisplatin (n = 8). Eighty‐nine of these 100 dogs had their tumors resected 3 weeks after the end of therapy (6 weeks after the initiation of therapy) and replaced with a cortical bone allograft. Dogs with preoperative treatment were evaluated for local tumor control and time to metastasis. The mean percent tumor necrosis in untreated osteosarcoma was 26.8%. The mean percent tumor necrosis for dogs receiving radiation only, IA cisplatin only, and IV cisplatin only was 81.6%, 49.1% and 23.8%, respectively. The mean percent tumor necrosis for dogs receiving radiation therapy plus IA cisplatin or radiation therapy plus IV cisplatin was 83.7% and 78.2%, respectively. There was no significant difference between percent tumor necrosis in untreated osteosarcoma compared with those receiving IV cisplatin, but there was a significant increase in percent tumor necrosis with all other treatments. A mathematic model for the effect of cisplatin and radiation dose was developed using multiple regression analysis. The radiation dose calculated to cause at least 80% tumor necrosis was 42.2 Gy (95% confidence interval [CI], 38.0 to 47.6 Gy) when radiation was given alone and 28.1 Gy (95% CI, 21.3 to 36.6 Gy) when radiation was combined with IA cisplatin. Areas of viable tumor tended to be most frequent adjacent to the articular cartilage and in the joint capsule. Percent tumor necrosis was strongly predictive for local tumor control; 28 of 32 dogs with greater than 80% tumor necrosis had local control, and only eight of 29 dogs with less than 79% tumor necrosis had local control (P = 0.0047). There was no correlation between percent tumor necrosis and time to metastasis.

Using units of CEM 43°C T90, local hyperthermia thermal dose can be delivered as prescribed

A randomized study was designed in dogs with spontaneous soft tissue sarcomas to gain information about the relationship between hyperthermia dose and outcome. The study compared two levels of thermal dose applied to dogs with heatable tumours, so it was necessary to deliver either a low (2-5 CEM 43°C T90) or high (20-50 CEM 43°C T90) thermal dose as precisely as possible. It was also desirable to have similar numbers of hyperthermia treatments in each thermal dose group. Identification of heatable tumours and randomization to high or low heat dose group was done during the first hyperthermia treatment. This was readily accomplished using mapping of temperatures in thermometry catheters, manual recording of thermal data, and visual inspection of raw thermal data with subsequent adjustment of the duration of the hyperthermia treatment. An analysis of precision of thermal dose delivery was conducted after approximately 50% of projected accrual had been met in a randomized phase III assessment of thermal dose effect. Fifty-four dogs were eligible for randomization; in 48 dogs the tumour was deemed heatable according to predetermined temperature criteria applied during the first heat treatment. Twenty-four dogs were randomized to the high heat dose group, and 24 to the low heat dose group. Median (range) total thermal dose for dogs in the high dose group was 43.5 CEM 43°C T90 (16.4-66.6) compared to 3.2 CEM 43°C T90 (2.1-4.6) for dogs in the low dose group. There was no overlap of thermal doses between groups. Thus, thermal dose could be delivered accurately, being within the predetermined range in 47 of the 48 dogs. Thermal dose quantified as CEM 43°C T50, however, did overlap between groups and the clinical significance of this finding will not be known until outcome data are analysed. Most dogs in both groups received five hyperthermia treatments. Median (range) treatment duration for dogs in the high dose group was 300min (147-692) compared to 111min (51-381) for dogs in the low dose group. Relatively simple but accurate methods of delivering prescribed thermal dose as described herein will aid the translation of clinical hyperthermia from the research setting into more general practice once the characteristics of the relationship between hyperthermia dose and outcome are understood.

Effects of Pd-bacteriopheophorbide (TOOKAD)-Mediated Photodynamic Therapy on Canine Prostate Pretreated with Ionizing Radiation

Abstract Huang, Z., Chen, Q., Trncic, N., LaRue, S. M., Brun, P., Wilson, B. C., Shapiro, H. and Hetzel, F. W. Effects of Pd-bacteriopheophorbide (TOOKAD)-Mediated Photodynamic Therapy on Canine Prostate Pretreated with Ionizing Radiation. Radiat. Res. 161, 723–731 (2004). The aim of this study was to evaluate the effects of photodynamic therapy (PDT) using a novel palladium bacteriopherophorbide photosensitizer TOOKAD (WST09) on canine prostate that had been pretreated with ionizing radiation. To produce a physiological and anatomical environment in canine prostate similar to that in patients for whom radiotherapy has failed, canine prostates (n = 4) were exposed to ionizing radiation (54 Gy) 5 to 6 months prior to interstitial TOOKAD-mediated PDT. Light irradiation (763 nm, 50–200 J/cm at 150 mW/cm from a 1-cm cylindrical diffusing fiber) was delivered during intravenous infusion of TOOKAD at 2 mg/kg over 10 min. Interstitial measurements of tissue oxygen profile (pO2) and of local light fluence rate were also measured. The prostates were harvested for histological examination 1 week after PDT. The baseline pO2 of preirradiated prostate was in the range 10–44 mmHg. The changes in relative light fluence rate during PDT ranged from 12 to 43%. The acute lesions were characterized by hemorrhagic necrosis, clearly distinguishable from the radiotherapy-induced pre-existing fibrosis. The lesion size was correlated with light fluence and comparable to that in unirradiated prostate treated with a similar TOOKAD-PDT protocol. There was no noticeable damage to the urethra, bladder or adjacent colon. The preliminary results obtained from a small number of animals indicate that TOOKAD-PDT can effectively ablate prostate pretreated with ionizing radiation, and so it may provide an alternative modality for those prostate cancer patients for whom radiotherapy has failed.

Intensity-Modulated and Image-Guided Radiation Therapy for Treatment of Genitourinary Carcinomas in Dogs

BACKGROUND External beam radiation therapy can be used to treat pelvic tumors in dogs, but its utility is limited by lack of efficacy data and associated late complications. HYPOTHESIS/OBJECTIVES The objective of this study was to assess local tumor control, overall survival, and toxicosis after intensity-modulated and image-guided radiation therapy (IM/IGRT) for treatment of genitourinary carcinomas (CGUC) in dogs. ANIMALS 21 client-owned dogs. METHODS A retrospective study was performed. Medical records of dogs for which there was intent to treat with a course of definitive-intent IM/IGRT for CGUC between 2008 and 2011 were reviewed. Descriptive and actuarial statistics comprised the data analysis. RESULTS Primary tumors were located in the prostate (10), urinary bladder (9), or urethra (2). The total radiation dose ranged from 54-58 Gy, delivered in 20 daily fractions. Grade 1 and 2 acute gastrointestinal toxicoses developed in 33 and 5% of dogs, respectively. Grade 1 and 2 acute genitourinary and grade 1 acute integumentary toxicoses were documented in 5, 5, and 20% of dogs, respectively. Four dogs experienced late grade 3 gastrointestinal or genitourinary toxicosis. The subjective response rate was 60%. The median event-free survival was 317 days; the overall median survival time was 654 days. Neither local tumor control nor overall survival was statistically dependent upon location of the primary tumor. CONCLUSIONS AND CLINICAL IMPORTANCE IM/IGRT is generally well-tolerated and provides an effective option for locoregional control of CGUC. As compared with previous reports in the veterinary literature, inclusion of IM/IGRT in multimodal treatment protocols for CGUC can result in superior survival times; controlled prospective evaluation is warranted.

Changes in tumour oxygenation during fractionated hyperthermia and radiation therapy in spontaneous canine sarcomas.

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.

A phase I trial of hyperthermia-induced interleukin-12 gene therapy in spontaneously arising feline soft tissue sarcomas

Interleukin-12 (IL-12), a proinflammatory cytokine, shows anticancer properties. Systemically administered IL-12 causes dose-dependent toxicity. To achieve localized intratumoral gene expression, an adenoviral gene therapy vector with IL-12 controlled by a heat-inducible promoter (heat shock promoter 70B) was developed and tested in a phase I clinical trial in cats with spontaneously arising soft tissue sarcoma. A feasibility study was done in 16 cats with soft tissue sarcoma using murine IL-12 and/or enhanced green fluorescent protein adenoviral vectors under cytomegalovirus or heat shock promoter 70 control. Subsequently, we conducted a phase I clinical trial using an adenoviral feline IL-12 construct in 13 cats with soft tissue sarcoma. The soft tissue sarcomas were irradiated (48 Gy/16 fractions) followed by intratumoral injection of adenovirus. Twenty-four hours postinjection, tumors were heated (41°C, 60 min). Tumor expression of feline IL-12 and IFN-γ was determined. Cats were monitored for systemic toxicity. For the murine IL-12 construct, an association was noted between viral dose and murine IL-12 levels within tumor, whereas serum levels were minimal. Mild toxicity was noted at 1011 plaque-forming units (pfu). With the feline IL-12 construct, high levels of feline IL-12 mRNA were detected in tumor biopsies with low or absent IFN-γ mRNA following gene therapy. Hematologic and hepatic toxicities were noted at the highest viral doses and were associated with detection of IFN-γ mRNA in tumor. It is possible to localize gene expression and limit systemic toxicity of IL-12 using the hyperthermia-induced gene therapy approach. The maximum tolerated dose of the feline IL-12 adenoviral vector was 1010 pfu/tumor as dose-limiting toxicities were noted at the 4 × 1010 pfu dose. [Mol Cancer Ther 2007;6(1):380–9]