Comparison of 3 protocols for treatment after induction of remission in dogs with lymphoma

BACKGROUND: The optimal treatment after inducing complete remission (CR) in dogs with lymphoma has not been established. HYPOTHESIS: After inducing CR with L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisone (L-CHOP); consolidation with either half-body radiation therapy (HBRT); or lomustine (CCNU) and mechlorethamine, vincristine, procarbazine, prednisone (MOPP) would improve first remission duration compared with continuing a CHOP-based protocol for an additional 4 months. ANIMALS: Dogs with stage III-V lymphoma. METHODS: Prospective clinical trial in which dogs initially were treated with an 8-week induction protocol that consisted of L-CHOP. Dogs in CR after induction were then allocated to 1 of 2 consolidation arms. A chemotherapy consolidation arm consisted of 2 treatments with CCNU and 1 cycle of MOPP. A HBRT arm consisted of 2 sequential 8.0-Gy fractions to the cranial and caudal half-body separated by 30 days. Vincristine was given between fractions. Results of the consolidation arms also were compared with a historical group treated with the same 8-week induction protocol followed by CHOP therapy until week 24. RESULTS: Overall, 67% of the dogs were in CR after 8 weeks of induction chemotherapy and were compared. Fifty-two dogs were in the historical arm, 23 in the CCNU/MOPP arm, and 27 in the HBRT arm. No difference in first remission duration was found among groups. Median first remission duration for the historical, CCNU/MOPP, and HBRT arms were 307, 274, and 209 days, respectively (P = .28). Overall second CR rate was 82% and was not different among groups (all P > or = .58). Overall remission duration (P = .28) and survival time (P = .48) were not different among groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Consolidation with either CCNU/MOPP or HBRT showed no advantage over a standard CHOP-based protocol.     

Establishment of a panel of reference Trypanosoma evansi and Trypanosoma equiperdum strains for drug screening

The animal pathogenic protozoan, Trypanosoma evansi, leads to a wasting disease in equines, cattle and camels, commonly known as Surra. It is extensively distributed geographically with a wide range of mammalian hosts and causes great economical loss. Trypanosoma equiperdum causes a venereal disease called Dourine in horses and donkeys. Chemotherapy appears to be the most effective form of control for T. evansi, whereas infections caused by T. equiperdum are considered incurable. Due to emerging drug resistance, efficient control of T. evansi is severely threatened, emphasising the urgent need to find new alternative drugs. A drug profile for a panel of T. evansi and T. equiperdum strains has been established for the four standard drugs currently used in treatment. The (3)H-hypoxanthine incorporation assay was used to obtain 50% inhibitory concentration (IC(50)) values for each standard drug against the various strains. The results indicate the presence (and in some cases, the emergence) of drug resistance in several strains. This panel of characterised strains with known drug sensitivities and resistances will be of great value for the screening of new active compounds, in comparison with the four standard drugs currently available.     

Effect of Wip1 gene silencing on chemotherapy sensitivity of human colon cancer cells

AIM: To observe the inhibitory effect of siRNA targeting to Wip1 gene on the Wip1 gene expression in the colon cancer cells and to investigate the influence of Wip1 gene silencing on the chemotherapy sensitivity of colon cancer cells. METHODS: Wip1-811 siRNA targeting to Wip1 gene was transfected into RKO colon cancer cells with high expression of Wip1 gene. The mRNA expression of Wip1 was measured by real-time PCR. The protein level of Wip1 was detected by Western blotting. The viability of RKO colon cancer cells was measured by MTS assay. The cell apoptosis and cell cycle were analyzed by flow cytometry. RESULTS: Wip1-811 siRNA efficiently inhibited the expression of Wip1 at mRNA and protein levels. The enhanced chemotherapy sensitivity of RKO colon cancer cells was observed after inhibition of Wip1 gene expression. The viability of RKO colon cancer cells was decreased from (89.4±6.6)% to (74.7±3.9)% after treated with 5-fluorouracil (P<0.05) and decreased from (77.9±2.4)% to (66.7±2.9)% after treated with oxaliplatin (P<0.05). The cell apoptotic rate was increased from (7.7±0.5)% to (12.3±3.2)% and from (14.7±2.1)% to (34.0±2.1)% when RKO colon cancer cells were treated with 5-fluorouracil and oxaliplatin, respectively (P<0.05). CONCLUSION: Wip1 gene silencing enhances chemotherapy sensitivity of colon cancer cells.     

Lomustine (CCNU) for the Treatment of Resistant Lymphoma in Dogs

Forty-three dogs with lymphoma that had relapsed or had failed to achieve complete remission to previous chemotherapy were treated with lomustine (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea [CCNU]) at a dosage of 90-100 mg/m2 body surface area p.o. every 3 weeks. Durable complete or partial responses occurred in 11 dogs for a median of 86 days. The acutely dose-limiting toxicosis was neutropenia 7 days after administration, resulting in a recommended dosage of 90 mg/m2. Cumulative thrombocytopenia occurred in dogs receiving continued CCNU treatment, and a dose interval of 3 weeks may be too short for continued administration of this drug. Toxicoses evident as fever or central nervous system signs or renal damage were uncommon or rare. CCNU is effective in the treatment of relapsed lymphoma.     

Babesiosis Caused by a Large Babesia Species in 7 Immunocompromised Dogs

Background: A large unnamed Babesia species was detected in a dog with lymphoma. It was unknown if this was an underrecognized pathogen.
Objective: Report the historical and clinicopathologic findings in 7 dogs with babesiosis caused by a large unnamed Babesia species characterize the 18S ribosomal ribonucleic acid (rRNA) genes.
Animals: Seven immunocompromised dogs from which the Babesia was isolated.
Methods: Retrospective case review. Cases were identified by a diagnostic laboratory, the attending clinicians were contacted and the medical records were reviewed. The Babesia sp. 18S rRNA genes were amplified and sequenced.
Results: Six of 7 dogs had been splenectomized; the remaining dog was receiving oncolytic drugs. Lethargy, anorexia, fever, and pigmenturia were reported in 6/7, 6/7, 4/7, and 3/7 dogs. Laboratory findings included mild anemia (7/7) and severe thrombocytopenia (6/7). Polymerase chain reaction (PCR) assays used to detect Babesia sensu stricto species were all positive, but specific PCR assays for Babesia canis and Babesia gibsoni were negative in all dogs. The 18S rRNA gene sequences were determined to be identical to a large unnamed Babesia sp. previously isolated. Cross-reactive antibodies against other Babesia spp. were not always detectable. Five dogs were treated with imidocarb dipropionate and 1 dog with atovaquone/azithromycin; some favorable responses were noted. The remaining dog was untreated and remained a clinically stable carrier.
Conclusions and Clinical Importance: Dogs with pigmenturia, anemia, and thrombocytopenia should be tested for Babesia sp. by PCR. Serology is not sufficient for diagnosis of this Babesia sp. Asplenia, chemotherapy, or both might represent risk factors for persistent infection, illness, or both.     

Cancer Chemotherapy: An Annotated History

Treating cancer with drugs is an ancient art, but it is from discoveries made during and after the Second World War that real clinical success with cancer chemotherapy has occurred. Human and veterinary cancer chemotherapy have coevolved in the context of fascinating historical, political, and scientific events created by equally fascinating individuals.     

Pharmacokinetic Modeling of Doxorubicin Pharmacokinetics in Dogs Deficient in ABCB1 Drug Transporters

Background: The identification of dogs defective in ATP‐binding cassette transporter B1 (ABCB1, MDR1) activity has prompted questions regarding pharmacokinetics (PK), efficacy and toxicity of ABCB1 substrates in these dogs. Hypothesis/Objectives: Dogs defective in ABCB1 activity (ABCB1_null) have doxorubicin (DOX) PK different from that of normal dogs (ABCB1_wt). Utilization of a physiologically based pharmacokinetic (PBPK) model allows computer simulation to study this polymorphism's impact on DOX PK. Animals: None. Methods: A virtual ABCB1_wt dog population was generated and DOX distribution, elimination, and metabolism simulated by PBPK modeling. An in silico population of virtual dogs was generated by Monte Carlo simulation, with variability in physiologic and biochemical parameters consistent with the dog population. This population was used in the PBPK model. The ABCB1 components of the model were inactivated to generate an ABCB1_null population and simulations repeated at multiple doses. Resulting DOX levels were used to generate PK parameters. Results: DOX exposures in the ABCB1_null population were increased in all simulated tissues including serum (24%) and gut (174%). Estimated dosages in the ABCB1_null population to approximate exposure in the ABCB1_wt population at a dose of 30 mg/m² were 24.8 ± 3.5 mg/m² for serum and 10.7 ± 5.9 mg/m² for gut. Conclusions and Clinical Importance: These results suggest that serum DOX concentrations are not indicative of tissue exposure, especially those with appreciable ABCB1 activity, and that gastrointestinal (GI) toxicosis would be dose limiting in ABCB1_null populations. Dosage reductions necessary to prevent GI toxicosis likely result in subtherapeutic concentrations, thereby reducing DOXs efficacy in ABCB1_null dogs.     

Intestinal parasite infections in dogs affected by multicentric lymphoma and undergoing chemotherapy

Prevalence and species composition of intestinal parasites were evaluated in dogs affected by high-grade multicentric lymphoma and undergoing chemotherapy and in control healthy dogs. Obtained data were statistically analyzed. The overall prevalence of intestinal parasite infections was 33.3%. In lymphoma dogs, the prevalence of protozoa infections (46.7%) was significantly higher (p < 0.05) than that of helminth infections (6.7%) and Giardia duodenalis, Cryptosporidium spp., Neospora caninum, Cystoisospora ohioensis-complex, Entamoeba sp. and Spirocerca lupi were identified. In the control group, only 3/15 dogs (20%) were found positive and no statistically significant differences emerged regarding helminth (hookworms and Toxocara canis) and protozoa (G. duodenalis) infections. Results from this study may suggest a potential higher prevalence of opportunistic intestinal protozoa, including some potentially zoonotic species, in dogs affected by high-grade multicentric lymphoma, emphasizing the need to monitor lymphoma-affected dogs for these protozoa, especially those undergoing chemotherapy.     

Response of human triple-negative breast cancer to paclitaxel after vascular normalization in nude mice

AIM: To explore whether there is synergistic effect of recombinant human endostatin (rh-Endo) and paclitaxel (Pac) in the time window of vascular normalization and the role of magnetic resonance imaging (MRI) in early assessment of chemotherapy by observing the response of human triple-negative breast cancer (TNBC) to Pac after vascular normalization in nude mice. METHODS: The human TNBC MDA-MB-231 cells were planted in the subcutaneous region of right lower abdomen of BALB/c-nu female nude mice. These nude mice were randomly divided into 4 groups (n=7). rh-Endo was given for 17 consecutive days in rh-Endo group and rh-Endo+Pac group. Pac was given on the 6th and 12th days in Pac group and rh-Endo+Pac group. The dosage of both drugs was 10 mg·kg^-1·d^-1 (ip). On the day before the treatment and the 5th, 11th and 17th days after treatment, all the transplanted tumors were examined by MRI. All the mice were killed by cervical dislocation and their transplanted tumors were taken down for examinations after the last MRI on the 17th day. The changes of pathology, immunohistochemisty, microvessel density (MVD) and Ki67 expression were measured. RESULTS: On the 17th day, the volume of transplanted tumor in rh-Endo+Pac group was smaller than that in model group and rh-Endo group (P<0.05), and no difference between rh-Endo+Pac group and Pac group was found. On the 17th day, the tumor inhibitory rates in rh-Endo group, Pac group and rh-Endo+Pac group were 14.61%, 39.08% and 54.79%, respectively. The slow diffusion coefficient in Pac group was increased compared with model group, while it was decreased compared with rh-Endo+Pac group (P<0.05). No distant metastatic lesion in the tumor-bearing mice was observed. The necrotic rates in rh-Endo+Pac group and Pac group were higher than those in model group and rh-Endo group. The MVD in model group was higher than that in the other 3 groups. The MVD in rh-Endo+Pac group was decreased compared with Pac group and rh-Endo group. The Ki67 level in rh-Endo+Pac group was decreased compared with rh-Endo group, and no difference between rh-Endo+Pac group and Pac group was detected.CONCLUSION: In the time window of vascular normalization, the combination of Pac and rh-Endo has a significant antitumor effect on TNBC, but this study did not observe a significant synergistic effect of the 2 drugs. The change of slow diffusion coefficient can predict the therapeutic effect in advance.