Carboplatin-induced myelosuppression as related to body weight in dogs

Impact of 10% Dose Reductions and Duration of Treatment Delays in the Management of Chemotherapy-Induced Neutropenia in Dogs Treated With Common Chemotherapy Protocols: A Single-Centre Experience

Neutropenia is a common chemotherapy-associated adverse event (AE) in dogs and a significant cause of decreased relative dose intensity. Dose reductions (DRs) and treatment delays (TDs) are frequently applied to decrease the risk of further neutropenic events (NEs) and AEs, but there is no standardised approach. The two main objectives of this retrospective study were to determine: (1) the failure rate of a 10% DR to prevent a subsequent inadequate absolute neutrophil count (ANC), defined as a nadir ANC <0.75 × 109/L or pretreatment ANC <1.5 × 109/L; and (2) if the duration of TDs due to pretreatment neutropenia affects the occurrence of subsequent NEs. A total of 1056 chemotherapy treatments were recorded for 128 dogs that developed at least one NE. In 75 of 124 (60.5%, 95% CI: 51.2%-69%) evaluable NEs, a nadir ANC of ≥0.75 × 109/L and pretreatment ANC of ≥1.5 × 109/L were achieved after a single 10% chemotherapy DR, while a 10% DR failed to prevent a subsequent inadequate ANC in the remaining 49/124 (39.5%, 95% CI: 30.1%-48.3%). The only variable associated with failure was the drug prescribed. DR failure occurred in 22/39 (56.4%, 95% CI: 40.9%-70.6%) lomustine DRs, 14/27 (51.9%, 95% CI: 33.9%-69.2%) cyclophosphamide DRs, but only 2/22 (9.1%, 95% CI: 2.5%-27.8%) doxorubicin DRs and 2/24 (8.3%, 95% CI: 2.3%-25.8%) vincristine DRs. Seventy-three evaluable TDs (mean: 5 days, SD ± 2.2 days) were prescribed. There was no association between TD duration and subsequent NEs (p = 0.11).

Ozone Therapy in the Integrated Treatment of Female Dogs with Mammary Cancer: Oxidative Profile and Quality of Life

Considering the high frequency of malignant breast tumors, there is a growing search for new therapeutic strategies that control neoplastic growth and dissemination, combined with fewer adverse reactions. Therefore, this study evaluated the effects of ozone therapy in female dogs with mammary cancer undergoing chemotherapy treatment. Twenty-five canines diagnosed with malignant mammary neoplasia were divided into two groups: one treated with carboplatin alone (n = 11) and the other with carboplatin associated with ozone therapy (n = 14). Clinical and laboratory evaluations, mastectomy, analysis of the oxidative profile based on total antioxidant capacity (TAC) and serum concentrations of malondialdehyde (MDA), survival rate, and quality of life were performed. Animals in the ozone therapy group had higher concentrations of red blood cells and platelets, significantly improving the survival rate and quality of life. Furthermore, adverse reactions were less intense and frequent in this group, which was associated with an increase in TAC and a reduction in MDA. These results indicate that the combination of carboplatin and ozone therapy represents a promising complementary treatment for female dogs with mammary cancer, as it was associated with fewer adverse reactions and a better oxidative profile.

Vincristine-induced adverse events related to body weight in dogs treated for lymphoma

BACKGROUND

Traditional dosing of chemotherapy drugs based on body surface area may overdose small dogs, leading to an increased frequency of adverse events (AEs).

HYPOTHESIS/OBJECTIVES

Evaluate the frequency of hematologic and gastrointestinal AEs in dogs with newly diagnosed lymphoma treated with vincristine weighing ≤15 kg in comparison to dogs weighing >15 kg. We hypothesized that dogs weighing ≤15 kg would experience a higher frequency of AEs.

ANIMALS

One hundred and thirty-eight dogs with newly diagnosed lymphoma were treated with vincristine.

METHODS

A multicenter retrospective study reviewing hematologic data and medical record information. Complete blood counts were performed no more than 24 hours before vincristine administration and then between 4 and 8 days post-administration. Data were evaluated using logistic regression or ordinal logistic regression.

RESULTS

Thirty-eight dogs weighing ≤15 kg and 100 dogs weighing >15 kg were included. The median vincristine dose for both groups was 0.6 mg/m2. Seventeen (12.3%) instances of neutropenia occurred with no significant difference in overall frequency or grade between groups. Thirty initially asymptomatic substage A dogs (29.4%) experienced gastrointestinal AEs. Because of the widespread use of gastrointestinal supportive care medications, statistical comparison between groups could not be performed. Seven instances of hospitalization occurred (5.0%) and the risk of hospitalization did not differ significantly between groups (P = .37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Vincristine dosed at ≤0.6 mg/m2 does not increase the risk of hematologic AEs in dogs weighing ≤15 kg.

A pilot study of chemotherapy combinations in rats: Focus on mammary cancer treatment in female dogs

The use of combined chemotherapy is an essential alternative in treating breast cancer. However, knowledge of the pharmacokinetics of drugs is necessary to obtain maximum efficiency of the protocol and reduce adverse reactions. This study suggests for the first time the effect of the association of carboplatin with ivermectin and carboplatin with cyclophosphamide. This investigation was performed with 36 healthy Wistar rats, divided into four groups: group control, carboplatin (C), carboplatin preceded by ivermectin (C + IV), and carboplatin associated with cyclophosphamide (C + CI). Plasma concentrations quantification was performed using the High-Performance Liquid Chromatographic (HPLC) equipment with an Ultraviolet (UV) detector at eight different time points. Then, the animal was euthanized and necropsied. The bioanalytical method was validated for the two matrices (dogs and rats' plasma), with full validation in female dogs and partial validation in rats, as recommended by the EMA. In both matrices, the method was linear and reproducible. Here, we show the results in female rats' plasma. When comparing the experimental rats' groups (C; C + IV, and C + CI), there is a tendency to increase the bioavailability of carboplatin when used in association, a slight increase for C + IV and more evident to the C + CI group with an AUC rise higher than 2-fold (AUC0-∞ = 2983.61 for C; 4459.06 for C + CI; 7064.68 for C + CI min·mg·mL-1). The blood count, biochemistry profile, and histopathology of the organs revealed only alterations inherent to the metabolic effects of the drugs used. The carboplatin association with ivermectin appeared safe for this pilot group. We believe the carboplatin dose can be maintained without risk to the patient. However, in the carboplatin association with cyclophosphamide, a slight reduction in carboplatin's amount is suggested, seeking to avoid increased effects due to cyclophosphamide. Thus, studies with a more significant number per group must confirm the relevance of this pilot study.

Pharmacokinetics of Carboplatin in Combination with Low-Dose Cyclophosphamide in Female Dogs with Mammary Carcinoma

This prospective study aimed to evaluate the effect of metronomic cyclophosphamide on carboplatin’s tolerability, efficacy, and pharmacokinetics in dogs with mammary carcinoma. Sixteen female dogs with mammary carcinoma were divided into groups: 300 mg/m2 intravenous (i.v.) carboplatin therapy (G1 = 8) or 300 mg/m2 i.v. carboplatin which was associated with 12.5 mg/m2 oral cyclophosphamide in a metronomic regimen (G2 = 8). The investigated animals underwent a clinical evaluation, a mastectomy, a carboplatin chemotherapy, and serial blood sampling for the pharmacokinetic analysis. The adverse events and survival rates were monitored. A non-compartmental analysis was applied to calculate the pharmacokinetic parameters of carboplatin in the 2nd and 4th chemotherapy cycles. Carboplatin PK showed high interindividual variability with a 10-fold variation in the area under the plasma concentration−time curve (AUC) in G1. The systemic plasma exposure to carboplatin was equivalent in both of the treatments considering the AUC and maximum plasma concentration (Cmax) values. Although the red blood cells (p < 0.0001), platelets (p = 0.0005), total leukocytes (p = 0.0002), and segmented neutrophils (p = 0.0007) were reduced in G2, the survival rate increased (p = 0.0044) when it was compared to G1. In conclusion, adding low daily doses of cyclophosphamide to a carboplatin therapy showed promising outcomes in female dogs with mammary tumors.

Retrospective Evaluation of a Combination of Carboplatin and Bleomycin for the Treatment of Canine Carcinomas

Carboplatin is a chemotherapy agent widely used in veterinary oncology to treat various types of tumors including carcinomas. Carboplatin has previously been used in combination with 5-Fluoro uracil (5-FU) or gemcitabine for the treatment of various carcinomas. Bleomycin is a chemotherapy drug commonly used in humans, but its use has been uncommonly reported in dogs. The combination of carboplatin and bleomycin chemotherapy treatment has never been reported in dogs. Dogs diagnosed with carcinoma and treated with a combination of carboplatin and bleomycin, at a single veterinary referral center, were retrospectively evaluated. Thirty patients met the inclusion criteria. The dose of carboplatin ranged from 200–250 mg/m2 (median 240 mg/m2) and the dose of bleomycin from 15–20 IU/m2 (median 15 IU/m2). The treatment with carboplatin and bleomycin was well tolerated, with sixteen patients (53%) developing side effects. Thirteen patients (46%) developed gastrointestinal signs and nine dogs (30%) developed hematological abnormalities. The most common side effects were grade-1 hyporexia and grade-1 neutropenia. Grade-2 neutropenia was rarely observed, and only one patient developed grade-3 neutropenia. None of the dogs developed grade-4 adverse events, or required hospitalization, or died due to the treatment. No signs of chronic side effects, including pulmonary toxicity, were observed. Objective response was observed in 24% of the cases (six partial responses) and 76% of cases achieved clinical benefit (partial response+ stable disease). Clinical signs improved in 24 of the 30 cases (80%). The main aim of this study was to evaluate the safety of bleomycin and carboplatin in combination for the treatment of various types of carcinomas. The combination of bleomycin and carboplatin appears safe and potentially effective for some types of carcinomas. Larger prospective studies are needed to confirm the safety and efficacy of combined carboplatin and bleomycin.

Are severe adverse events commonly observed in dogs during cancer chemotherapy? A retrospective study on 155 dogs

Overall prevalence of severe adverse events (sAE) has been poorly studied in veterinary medicine and peer-reviewed studies mostly focused on a single protocol, making it difficult to have a general overview. The aim of this retrospective study was to assess the frequency and risk factors of sAE secondary to various protocols of chemotherapy in dogs. Medical records of 155 dogs receiving chemotherapy between January 2013 and December 2018 were reviewed. Adverse events (AE) were graded according to Veterinary Comparative Oncology Group-common terminology criteria for AE (VCOG-CTCAE) grading system. Statistical analyses were performed to determine whether demographic, cancer type and chemotherapy protocol were associated with development of sAE and their consequences. AE were reported at least once in 124 (80%) dogs and sAE were observed in 50 (32.3%) dogs. Among them, 23 (14.8%) had gastro-intestinal and 31 (20.0%) had myelotoxic events. sAE led to hospitalisation in 37 (23.9%) dogs, to chemotherapy arrest in 12 (7.7%) dogs and to euthanasia or death in 9 (5.8%) dogs. Haematopoietic tumours were statistically associated with a higher frequency of sAE (p = .004), gastrointestinal sAE (p = .009) and hospitalisation (p = .004). A body weight over 10 kg was associated with less haematological sAE (p < .001). The use of a multi-agent protocol was highlighted as a risk factor for sAE (p = .038) and haematological sAE (p < .001). sAE following chemotherapy and leading to hospitalisation, chemo arrest or death were relatively common. A special attention during chemotherapy follow-up should be given to small dogs and those receiving multi-agent protocol or treated for haematopoietic tumours.

A retrospective analysis on the outcome of 18 dogs with malignant ovarian tumours

Little evidence is available regarding the prognosis of dogs with malignant ovarian tumours. The objective of this retrospective study was to describe the outcomes and determine the prognostic factors for dogs with malignant ovarian tumours following treatment, including surgery with or without adjuvant therapy. Eighteen dogs were studied, their median age was 12 years (range: 7-15 years), and their median body weight was 6.9 kg (range: 2.3-17.8 kg). Following histopathologic diagnoses revealed that granulosa cell tumour was the most common type (n = 9), followed by dysgerminoma (n = 5), and adenocarcinoma (n = 4). Eleven dogs had surgery alone. Seven dogs had surgery with adjuvant therapy, including chemotherapy and/or radiotherapy. The median survival time (ST) was 1009 days when only deaths owing to the ovarian tumours were considered, and predictors of median ST were T-category (≥ T3, 443 days vs ≤ T2, 1474 days; P = .002), presence of metastatic disease (present, 391 days vs absent, 1474 days; P < .001) and lymphovascular space invasion (present, 428 days vs absent, 1474 days; P = .003) in a univariate analysis. Median ST in dogs with granulosa cell tumour seemed longer than in dogs with dysgerminoma and adenocarcinoma, although the difference was statistically insignificant (1474 days vs 458 days, respectively; P = .10). Considering the good prognosis, aggressive treatment can be recommended for dogs with malignant ovarian tumours, especially early-stage cases. Despite metastasis being present at diagnosis, half of the dogs with metastasis survived for more than 1 year.