[An oral repeated dose toxicity study of a new antineoplastic agent S-1 in dogs. I. A 13-week repeated dose toxicity study. II. An ophthalmologic toxicity recovery study]

Preclinical/clinical trials of thrice-weekly administration of a combination of tegafur/gimeracil/oteracil (TS-1) and toceranib phosphate in dogs with intranasal tumors

Intranasal tumors in dogs are malignant solid tumors that are primarily treated with radiotherapy and often recur post-treatment. Combination therapy is pivotal in cancer therapy. Effective drugs include fluoropyrimidine 5-fluorouracil (5-FU) and toceranib phosphate. TS-1, an oral formulation containing the 5-FU prodrug tegafur and enzyme modulators gimeracil and oteracil, is proven to be safe in dogs with solid tumors. While the oral drug toceranib phosphate (Palladia®) is safely administered, the combined toxicity with TS-1 is unknown. We aimed to determine the dosage of this combination in dogs. In the preclinical/clinical trials conducted here, we used a standard 3+3 cohort design with fixed doses of toceranib phosphate (2.4 mg/kg) administered thrice weekly. TS-1 administration was initiated at a dose of 0.5 mg/kg (upper limit 2.0 mg/kg) thrice weekly. Four cohorts were included to confirm the safety of TS-1 and toceranib phosphate. Each cohort was followed up for 1 month. The intranasal tumor types included in the clinical trial (n=13) were adenocarcinoma (n=7), squamous cell carcinoma (n=1), non-epithelial malignancy (n=2), undifferentiated carcinoma (n=1), and transitional carcinoma (n=2). The TS-1 dosage could be increased up to its dose limit in the preclinical/clinical trials. The TS-1 dose to combine with toceranib phosphate thrice weekly was 2.0 mg/kg. This regimen was well-tolerated in dogs. Thus, combined TS-1 and toceranib phosphate therapy is safe for dogs with intranasal tumors.

Causes of Tearing in Patients With Chemotherapy: Meibomian Gland Dysfunction Versus Lacrimal Drainage Obstruction

Numerous ocular toxicities that have been associated with the use of chemotherapeutic agents present as problems with the ocular surface, ocular adnexa, and lacrimal system, and many chemotherapeutic agents have tearing as a side effect. In this study, 34 eyes from 17 patients with a mean age of 62.4±14.8 years were analyzed. Chemotherapy was administered for a mean of 13.8±7.6 months. Chemotherapeutic agents of the following types were included: titanium silicate-1 (58.8%), Docetaxel (23.5%), Paclitaxel (11.8%), and 5-fluorouracil (5.9%). Tearing began 9.1 to 10.9 months after chemotherapy treatment. Within 3 months of beginning chemotherapy, tearing occurred in 9 patients (52.9%), and within 6 months, it occurred in 11 patients (64.7%). Mean tear break-up time was 5.4±2.6 sec. Ten eyes (29.4%) had normal fluorescein dye disappearance test findings (within grade 1), and the mean fluorescein dye disappearance test was 1.91±0.87. Among the 34 eyes, 24 (70.6%) had normal puncta and 9 (26.5%) and 1 (2.9%) had stenosis and blockage, respectively. Ten eyes (29.4%) showed total regurgitation, 19 eyes (55.9%) showed partial regurgitation, and 5 eyes (14.7%) showed no regurgitation upon syringing. Four eyes (11.8%) and 30 eyes (88.2%), respectively, showed soft and hard stops upon probing. Dacryoscintigraphy confirmed that 6 eyes (17.6%) were normal, 8 eyes (23.5%) showed post-sac delay or obstruction, and 20 eyes (58.8%) showed pre-sac delay or obstruction. The mean meiboscores for the upper and lower eyelids on LipiView were 2.15±0.86 and 2.53±0.79, respectively. The difference in meiboscores between the upper and lower eyelids was significant (P=0.004). Obstruction of the lacrimal drainage system is a significant contributing factor to tearing in chemotherapy patients. However, reflex tearing because of meibomian gland dysfunction should also be fully considered to effectively manage the tearing because of the high incidence of accompanying meibomian glands loss when the lacrimal drainage system is obstructed.

Safety of alternate-day treatment with TS-1TM (tegafur/gimeracil/oteracil) in tumor-bearing dogs: a pilot study

Tegafur is a prodrug of fluoropyrimidine 5-fluorouracil (5-FU), while TS-1^TM is an oral fixed-dose combination of three active drugs, tegafur, gimeracil, and oteracil. This pilot study evaluated the safety of tegafur/gimeracil/oteracil in the treatment of cancers in dogs. Tegafur/gimeracil/oteracil was administered orally at a mean dose of 1.1 mg/kg twice daily on alternate days, Monday-Wednesday-Friday, every week to 11 dogs with tumors. Partial response and stable disease were observed in one dog each, whereas six exhibited progressive disease. Three dogs were not assessed. Adverse events, the most serious being grade 2, were noted in seven dogs. Adverse events were acceptable, and the drug was effective in some dogs. Therefore, tegafur/gimeracil/oteracil may be useful for treating malignant solid tumors in canines.

Abnormalities in the meibomian glands in patients with oral administration of anticancer combination drug-capsule TS-1(®): a case report

BACKGROUND

The anticancer TS-1(®) combination capsules of tegafur, gimeracil, and oteracil potassium (Taiho Pharmaceutical Co. Ltd, Japan) causes side effects, i. e., corneal epithelial disorder and dacryostenosis. However, its side effect on meibomian gland had not been reported. We observed morphological changes in the meibomian gland in patients taking TS-1(®) who exhibited punctate corneal epithelial defects to examine if dysfunction of meibomian glands is involved in the corneal epitheliopathy.

CASE PRESENTATION

Patients comprised two males and one female (age, 59-81 years). After starting oral TS-1(®) administration, patients developed subjective symptoms such as decreased visual acuity. Corneal epithelial disorder was seen in all six eyes of the three subjects exhibited, and lacrimal duct disorder was seen in one eye. Furthermore, meibomian gland loss and contraction were observed in all six eyes that exhibited meibomian gland disorder upon examination by using the MeiboPen(®).

CONCLUSIONS

Results suggested that oral administration of TS-1(®) may cause meibomian gland disorder which potentially affect corneal epithelial homeostasis.

Alteration in the radiation-induced LD release in HeLa cells by acyclovir

The aim of the present investigation was to study the effect of various concentrations of acyclovir (ACV) alone or the effect of 0.1 micromol/l acycloir pretreatment on the radion-induced lactate dehydrogenase (LD) release by HeLa cells exposed to 0-3 Gy of gamma-radiation. The plateau-phase cells were treated with 0-100 micromol/l ACV for 8 h or 0.1 micromol/l ACV before exposure to 0-3 Gy of gamma-radiation. The whole media was removed from the culture and the LD release was measured at 0, 0.5, 1, 2, and 4 h post-drug treatment or post-irradiation. The ACV treatment resulted in a concentration-dependent elevation in the LD release at all the post-treatment time periods. A peak level for LD release was observed at 0 h up to 1 micromol/l ACV and declined thereafter. However, at higher doses a highest elevation in LD release was observed at 1 h post-treatment. Pretreatment of HeLa cells with 0.1 micromol/l ACV before irradiation to different doses of gamma-radiation resulted in significant elevation in the release of LD in the medium. The LD release was twofold greater in the ACV+irradiation group at 0 h post-irridiation when compared with the concurrent PBS+gamma-radiation group. The highest increase in LD activity was observed at 0 h post-irradiation and a gradual decline thereafter, without restoration to non-drug treated control level up to 4 h post-irradiation. The LD measurements can serve as a short-term assay to evaluate the cytotoxicity of ACV or radiation in vitro.