Intra-operative cisplatin for the treatment of canine extremity soft tissue sarcomas

Pharmacokinetic and safety assessment of carboplatin-impregnated calcium sulfate hemihydrate beads in eight rats

OBJECTIVE

Evaluate local tissue toxicity and plasma platinum (Pt) in vivo after subcutaneous implantation of carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Eight male Sprague-Dawley rats.

METHODS

CI-CSH beads were implanted subcutaneously (5 mg carboplatin/rat; 13.5 mg/kg carboplatin; 7.08 mg/kg Pt; 1.18 mg/m² Pt) in eight rats (d0). Wound healing (daily), radiographic bead dissolution (weekly), systemic Pt uptake (plasma-Pt), local tissue Pt (d28), and histologic changes compared to nonincised and incised catheterization sites (d28) were assessed. Blood and tissue samples were analyzed by inductively coupled plasma mass spectrometry for Pt, and pharmacokinetic analysis was performed using noncompartmental methods.

RESULTS

One rat died at d10, the remainder survived until d28. No wound complications were seen. The CI-CSH implantation site had higher histopathology scores than the other sites for necrosis (p = .013) and fibrosis (p = .013). Beads decreased in density radiographically (d0 to d28) (p = .062). Peak plasma-Pt concentration was 225.78 ng/ml at 12 h, and decreased over time, but Pt was still detectable on d28. The elimination half-life was 5.03 ± 1.13 days. Only 1.69% of implanted Pt remained in the beads at d28.

CONCLUSIONS

CI-CSH beads incited microscopic mild inflammation but wound healing was not impaired. Pt was absorbed systemically and the release from the beads was near complete at d28.

CLINICAL SIGNIFICANCE

Piled CI-CSH bead implantation is well tolerated in rats with similar elution profile as previously described. Beads were radiographically visible at d28. Minimal Pt was detected systemically suggesting Pt release does not match bead dissolution.

Local Administration of Carboplatin in Poloxamer 407 After an Ulnar Osteosarcoma Removal in a Dog

An 8 yr old male castrated hound presented for a left distal ulnar osteosarcoma. Staging (computed tomography and nuclear scintigraphy) did not reveal any metastases. A limb-sparing ulnectomy with local adjunctive carboplatin in a poloxamer copolymer gel (poloxamer 407) was performed. The patient recovered without complications after surgery. No wound healing complications or adverse effects occurred after local use of carboplatin in poloxamer 407. The local recurrence-free interval was 296 days from surgery, and the survival time was 445 days from initial diagnosis. This is the first report in the veterinary literature of using poloxamer 407 as a carrier for local delivery of chemotherapeutic drugs in a clinical patient.

Repeatability of in vitro carboplatin elution from carboplatin-impregnated calcium sulfate hemihydrate beads made in a clinic setting

OBJECTIVE

To evaluate the intra-lot and inter-lot consistency and total carboplatin elution over 25 days from carboplatin-impregnated calcium sulfate hemihydrate (C-I CSH) beads manufactured in a clinic setting.

STUDY DESIGN

In vitro elution study.

METHODS

Two volumes of carboplatin were mixed with CSH to yield 4 mg and 8 mg C-I CSH doses. Two lots of beads were made for each concentration and split into five doses (n = 10 per concentration). Beads hardened in molds and were placed in a covered six-well plate, submerged in phosphate-buffered saline, and incubated with samples collected at 12 time points (0, 6, 12, and 24 hours and 2, 3, 5, 7, 10, 14, 18, and 25 days). The amount of carboplatin in each sample was evaluated by high-performance liquid chromatography/mass spectrometry. Correction for carboplatin degradation and dilution was applied, and eluted carboplatin was calculated. Intra-lot and inter-lot coefficient of variation (CV) was calculated for each concentration.

RESULTS

The intra-lot CV ranged between 7.9% and 23.1%, and the inter-lot CV ranged from 3.5% to 10.3%, with improvement noted in each successive lot of beads. Mean peak eluted carboplatin was 2.45 ± 0.43 mg (61%) and 3.68 ± 0.41 mg (45.9%) for the 4-mg and 8-mg C-I CSH beads, respectively, with both occurring at the 12-hour timepoint.

CONCLUSION

Progressive improvement in variability with successive lots of beads indicated a learning curve with bead manufacturing with a low variation both within and between lots of C-I CSH beads.

CLINICAL SIGNIFICANCE

On-site mixing of carboplatin with commercial CSH bead powder leads to a low variation of carboplatin per bead dose.

Pharmacokinetics of platinum and safety evaluation of carboplatin-impregnated calcium sulfate hemihydrate beads after implantation in healthy cats

OBJECTIVE

To evaluate the pharmacokinetics (PK) of platinum (Pt) and safety of carboplatin-impregnated calcium sulfate hemihydrate (C-I CSH) beads after implantation in healthy cats.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Six healthy adult cats.

METHODS

Three C-I CSH beads were implanted in muscle pockets over the right and left hemithoraces of each cat (~3.9 mg/kg of Pt; 60.4 mg/m² of calculated carboplatin). Hematology and blood chemistry were tested at baseline and 3, 7, 14, and 21 days postimplantation. Serum was analyzed for Pt at specific times from 1 hour to 21 days. Tissue was obtained for histopathology and analysis of Pt at 3, 7, 14, and 21 days at standardized distances from implantation sites.

RESULTS

Platinum was detected in tissues at all times and distances (range, 0.1-4.19 μg/g). Serum Pt increased up to 2.6 hours (3.25 μg/mL) then decreased sharply. Samples containing muscle had higher Pt compared with samples without muscle (P = .004). Mild hypercalcemia was noted in four cats, and mild inflammatory reaction was noted on histopathology of all samples.

CONCLUSION

Platinum was released from C-I CSH beads differentially into surrounding tissues over 21 days. Systemic absorption of Pt was minimal, but mild hypercalcemia occurred.

CLINICAL SIGNIFICANCE

Implantation was well tolerated by healthy adult cats. Securing beads within muscle may limit Pt diffusion to targeted tissue. Although Pt concentrations did not achieve levels reported to be cytotoxic for feline sarcoma cells in culture, results provide evidence to support evaluation of efficacy in the tumor microenvironment of cats with locally invasive cancers.

Soft tissue sarcoma in dogs: A treatment review and a novel approach using electrochemotherapy in a case series

Canine soft tissue sarcomas (STSs) are locally invasive mesenchymal neoplasms. Electrochemotherapy (ECT) is an antitumour local ablative treatment that uses electric pulses to enhance the intracellular delivery of cytotoxic drugs. The aim of this retrospective study was to review the current treatment for STSs and to evaluate the efficacy and safety of ECT with bleomycin in canine STSs. Fifty-two dogs with 54 STSs were included. Three groups were arranged: (a) ECT alone, (b) intra-operative ECT and (c) adjuvant ECT. Signalment, tumour size, location, histological grade and margins and ECT parameters were collected. Recurrence rate (RR) and disease-free interval (DFI) were calculated. Treatment toxicity was assessed using a 6-point scale. STSs were mostly located on limbs (77.8%). Median tumour size was 4.3 cm (range 0.4-17.0 cm). Most STSs were grade I (47.7%) and II (50.0%), and histological margins were incomplete in 94.5% of cases. Two complete remissions, one partial remission and one stable disease were recorded in group 1. Group 2 and 3 were similar for tumour location, size and grade, histological margins, treatment toxicity, pulse frequency and voltage. Moreover, RR and DFI were similar between group 2 and 3 (23% and 25%, 81.5 and 243 days, respectively). Local toxicity post ECT was mild (score ≤ 2) in 66.7% of cases. Higher toxicity score was associated with higher pulse voltage (1200 vs 1000 V/cm) (P = 0.0473). ECT coupled with bleomycin resulted safe and efficient in tumour local control and should be considered as an option for treatment of canine STSs.

Therapeutic strategies for locally recurrent and metastatic de-differentiated liposarcoma with herpes simplex virus-thymidine kinase-expressing mesenchymal stromal cells

BACKGROUND AIMS

Major challenges in de-differentiated liposarcoma (DDLPS) therapy are the high rate of sequential recurrence (>80%) and metastasis (20-30%) following surgical removal. However, well-defined therapeutic strategies for this rare malignancy are lacking and are critically needed.

METHODS

We investigated a new approach to DDLPS therapy with mesenchymal stromal cells expressing herpes simplex virus-thymidine kinase (MSC-TK). In an effort to evaluate this efficacy, in vitro cytotoxicity of MSC-TK against DDLPS cells was analyzed using an apoptosis assay. For pre-clinical study, the MSC-TK-induced reduction in recurrence and metastasis was validated in a recurrent DDLPS model after the macroscopic complete resection and lung metastasis DDLPS model.

RESULTS

MSC-TK induced apoptosis in DDLPS cells by bystander effects via gap junction intracellular communication (GJIC) of toxic ganciclovir (GCV). Recurrent DDLPS models following no residual tumor/microscopic tumor resection and lung metastasis DDLPS models were established, which suggested clinical relevance. MSC-TK markedly reduced locoregional recurrence rates and prolonged recurrence-free survival, thus increasing overall survival in the recurrent DDLPS model. MSC-TK followed by GCV treatment yielded a statistically significant reduction in early- and advanced-stage lung metastasis.

DISCUSSION

This therapeutic strategy may serve as an alternative or additional strategy by applying MSC-TK to target residual tumors following surgical resection, thus reducing local relapse and metastasis in these patients.

THE MANAGEMENT OF AN ORAL ANAPLASTIC SARCOMA IN A PYGMY HIPPOPOTAMUS (CHOEROPSIS LIBERIENSIS) USING INTRALESIONAL CHEMOTHERAPY

An adult female captive pygmy hippopotamus (Choeropsis liberiensis) was diagnosed with an oral anaplastic sarcoma. The tumor was surgically debulked and intralesional chemotherapy with mitomycin C (0.4 mg/cm³ of tumor) and cisplatin (1 mg/cm³ of tumor) was administered. Chemotherapeutic treatment proved difficult due to the risks of repeated anesthetics and unknown drug efficacies. Marked proliferation of the mass was observed during estrus, and chemotherapy was repeated as an experimental treatment to slow tumor progression in order for the animal to remain in the species breeding program. Tumor proliferation was detected during the first trimester of pregnancy; however, in the lactation period, the mass became quiescent. No adverse reactions to chemotherapeutic drugs were observed and the animal continues to be monitored for tumor progression. This is the first report of an anaplastic sarcoma and of chemotherapy use in a pygmy hippopotamus and it highlights logistical considerations for treating neoplasia in this species.

Effects of intratumoral administration of a hyaluronan-cisplatin nanoconjugate to five dogs with soft tissue sarcomas

OBJECTIVE

To determine the effects of intratumoral injection of a hyaluronan-cisplatin nanoconjugate on local and systemic platinum concentrations and systemic toxicosis.

ANIMALS

5 dogs with spontaneous soft tissue sarcomas (STSs).

PROCEDURES

For each dog, approximately 1.5 mL of hyaluronan nanocarrier conjugated with 20 mg of cisplatin was injected into an external STS. Blood samples were collected immediately before (0 hours) and at 0.5, 1, 2, 3, 4, 24, and 96 hours after hyaluronan-cisplatin injection for pharmacokinetic analyses. Urine samples were obtained at 0 and at 96 hours after hyaluronan-cisplatin injection for urinalysis. Each treated STS and its sentinel lymph nodes were surgically removed 96 hours after the hyaluronan-cisplatin injection. Inductively coupled plasma mass spectrometry was used to measure platinum concentrations in blood samples, tumors, and lymph nodes.

RESULTS

No tissue reactions were detected 96 hours after hyaluronan-cisplatin injection. Mean ± SD area under the curve, peak concentration, and terminal half-life for unbound (plasma) and total (serum) platinum were 774.6 ± 221.1 ng•h/mL and 3,562.1 ± 2,031.1 ng•h/mL, 56.5 ± 20.9 ng/mL and 81.6 ± 40.4 ng/mL, and 33.6 ± 16.1 hours and 51.2 ± 29.1 hours, respectively. Platinum concentrations ranged from 3,325 to 8,229 ng/g in STSs and 130 to 6,066 ng/g in STS-associated lymph nodes.

CONCLUSIONS AND CLINICAL RELEVANCE

Intratumoral injection of the hyaluronan-cisplatin nanoconjugate was well tolerated in treated dogs. Following intratumoral hyaluronan-cisplatin injection, platinum concentration was 1,000-fold and 100-fold greater within treated tumors and tumor-draining lymphatics, respectively, compared with that in plasma.