In vivo pharmacokinetic and tissue distribution investigation of sustained-release cisplatin implants in the normal esophageal submucosa of 12 beagle dogs

A Simple Preparation Method of Gelatin Hydrogels Incorporating Cisplatin for Sustained Release

The objective of this study was to develop a new preparation method for cisplatin (CDDP)-incorporated gelatin hydrogels without using chemical crosslinking nor a vacuum heating instrument for dehydrothermal crosslinking. By simply mixing CDDP and gelatin, CDDP-crosslinked gelatin hydrogels (CCGH) were prepared. CDDP functions as a crosslinking agent of gelatin to form the gelatin hydrogel. Simultaneously, CDDP is incorporated into the gelatin hydrogel as a controlled release carrier. CDDP's in vitro and in vivo anticancer efficacy after incorporation into CCGH was evaluated. In the in vitro system, the CDDP was released gradually due to CCGH degradation with an initial burst release of approximately 16%. CDDP metal-coordinated with the degraded fragment of gelatin was released from CCGH with maintaining the anticancer activity. After intraperitoneal administration of CCGH, CDDP was detected in the blood circulation while its toxicity was low. Following intraperitoneal administration of CCGH in a murine peritoneal dissemination model of human gastric cancer MKN45-Luc cell line, the survival time was significantly prolonged compared with free CDDP solution. It is concluded that CCGH prepared by the CDDP-based crosslinking of gelatin is an excellent sustained release system of CDDP to achieve superior anticancer effects with minimal side effects compared with free CDDP solution.

Establishment of a direct 2.5D organoid culture model using companion animal cancer tissues

Like humans, cancer affects companion animals with similar genetic risks and incident rates. To improve treatment strategies for pet cancers, new research models are necessary. Patient-derived 3D organoid culture models are valuable and ensure the development of new effective therapies. In the previous study, we established a 3D organoid-derived 2.5D organoid culture model that recapitulated some characteristics of their parental 3D organoids. In the present study, we aimed to generate a 2.5D organoid culture model directly from cancer-diseased dogs and cats using special 2.5D media. The primary cultured cells in 2.5D media (direct 2.5D organoids) showed better attachment, growth, marker expression, and faster proliferation speed than those cultured in normal Dulbecco's Modified Eagle Medium media. The direct 2.5D organoids showed expression of each specific marker to their original cancer tissues and exhibited tumorigenesis in vivo. Moreover, the direct 2.5D organoids exhibited concentration-dependent responses to anti-cancer drugs, and different sensitivity profiles were shown among the strains. Our data suggest that the direct 2.5D organoid culture model might become a useful tool beyond 2D cell lines to study cancer biology in companion animals and could provide new platforms for screening the anti-cancer drugs.

Sorafenib and Doxorubicin Show Synergistic Effects in Human and Canine Osteosarcoma Cell Lines

Osteosarcoma (OSA) is the most common bone tumor in both humans and dogs and has a nearly ten-fold higher incidence in dogs than humans. Despite advances in the treatment of other cancers, the overall survival rates for OSA have stagnated for the past four decades. Therefore, there is a great need to identify novel and effective treatments. We screened a series of tyrosine kinase inhibitors and selected sorafenib, a multi-kinase inhibitor, for further evaluation alone and in combination with cisplatin, carboplatin, and doxorubicin on canine and human OSA cell lines. Our data point to synergistic effects when sorafenib is combined with doxorubicin, but not when combined with cisplatin or carboplatin, in both human and canine OSA. Based on current findings, clinical trials using a combination of doxorubicin and sorafenib in proof-of-concept studies in dogs are warranted. These studies can be carried out relatively quickly in dogs where case load is high and, in turn, provide useful data for the initiation of clinical trials in humans.

Significance of platinum distribution to predict platinum resistance in ovarian cancer after platinum treatment in neoadjuvant chemotherapy

Most patients with ovarian cancer experience recurrence and develop resistance to platinum-based agents. The diagnosis of platinum resistance based on the platinum-free interval is not always accurate and timely in clinical settings. Herein, we used laser ablation inductively coupled plasma mass spectrometry to visualize the platinum distribution in the ovarian cancer tissues at the time of interval debulking surgery after neoadjuvant chemotherapy in 27patients with advanced high-grade serous ovarian cancer. Two distinct patterns of platinum distribution were observed. Type A (n = 16): platinum accumulation at the adjacent stroma but little in the tumor; type B (n = 11): even distribution of platinum throughout the tumor and adjacent stroma. The type A patients treated post-surgery with platinum-based adjuvant chemotherapy showed significantly shorter periods of recurrence after the last platinum-based chemotherapy session (p = 0.020) and were diagnosed with “platinum-resistant recurrence”. Moreover, type A was significantly correlated with worse prognosis (p = 0.031). Post-surgery treatment with non-platinum-based chemotherapy could be effective for the patients classified as type A. Our findings indicate that the platinum resistance can be predicted prior to recurrence, based on the platinum distribution; this could contribute to the selection of more appropriate adjuvant chemotherapy, which may lead to improves prognoses.

Vincristine, carboplatin and cisplatin increase oxidative burst induced by PAF in canine neutrophils

Myelosupression resulting from chemotherapy has been widely described in veterinary medicine; however, there is limited information relating to alterations in neutrophil function after chemotherapy in dogs with cancer. The aim of this study was to determine the non-proliferative effects of vincristine, carboplatin, and cisplatin on canine neutrophils by evaluating activation of oxidative and non-oxidative responses. Neutrophils were isolated from venous blood. Levels of reactive oxygen species (ROS) and metalloproteinase 9 (MMP-9) were measured in vitro during neutrophil exposure to these chemotherapeutic agents for 15 min followed by stimulation with platelet activating factor (PAF). ROS production was detected via luminescence, and MMP- 9 liberation was determined by zymography. The chemotherapeutic agents caused an increase in PAF-induced ROS production, but no change in the non-oxidative response was observed. These results suggest that these chemotherapeutic agents may act as priming agents by increasing the oxidative response. These effects could be beneficial for dogs with cancer by supporting their immune systems; however, excessive ROS liberation has been associated with inflammation, neutrophil-mediated cell injury, carcinogenesis, and metastasis. Clinical studies are necessary to evaluate the significance of these findings.

Diplatin, a Novel and Low-Toxicity Anti-Lung Cancer Platinum Complex, Activation of Cell Death in Tumors via a ROS/JNK/p53-Dependent Pathway, and a Low Rate of Acquired Treatment Resistance

Background: Platinum-based drugs prevail as the main treatment of lung cancer; this is caused by their relative effectiveness despite known side effects, such as neurotoxicity. The risk reward of the treatment and side effects is confronted when dosage is considered and when resistance to treatment develops. Development of new compounds that improve effectiveness and safety profiles addresses this ongoing need in clinical practice.

Objectives: The novel water-soluble platinum complex, diplatin, was synthesized, and its antitumor potency and toxicology profile were evaluated in murine xenograft tumor models and in lung cancer cell lines.

Methods: The effects of diplatin, cisplatin (DDP), and carboplatin (CBP) on the viability of nine lung tumor cell lines and one normal human lung epithelial cell line were evaluated using the MTT assay. Therapeutic index was calculated as LD₅₀/ED₅₀ to identify and compare the ideal therapeutic windows of the above compounds. Diplatin’s antitumor effects were assessed in lung xenograft tumors of nude mice; molecular mechanisms of therapeutic effects were identified.

Results: Diplatin had desirable IC₅₀ compared to CBP in a variety of cultured tumor cells, notably lung tumor cells. In the mouse xenograft lung tumor, diplatin led to a substantially improved therapeutic index when compared to the effects of DDP and CBP. Importantly, diplatin inhibited the growth of DDP-resistant lung tumor cells. Diplatin’s mode of action was characterized to be through cell cycle arrest in the G2/M phase and induction of lung tumor apoptosis via ROS/JNK/p53-mediated pathways.

Conclusion: Diplatin was observed to have antitumor effects in mice with both greater potency and safety compared with DDP and CBP. These observations indicate that diplatin is promising as a potential treatment in future clinical applications.

Establishment of a novel experimental model for muscle-invasive bladder cancer using a dog bladder cancer organoid culture

In human and dogs, bladder cancer (BC) is the most common neoplasm affecting the urinary tract. Dog BC resembles human muscle‐invasive BC in histopathological characteristics and gene expression profiles, and could be an important research model for this disease. Cancer patient‐derived organoid culture can recapitulate organ structures and maintains the gene expression profiles of original tumor tissues. In a previous study, we generated dog prostate cancer organoids using urine samples, however dog BC organoids had never been produced. Therefore we aimed to generate dog BC organoids using urine samples and check their histopathological characteristics, drug sensitivity, and gene expression profiles. Organoids from individual BC dogs were successfully generated, expressed urothelial cell markers (CK7, CK20, and UPK3A) and exhibited tumorigenesis in vivo. In a cell viability assay, the response to combined treatment with a range of anticancer drugs (cisplatin, vinblastine, gemcitabine or piroxicam) was markedly different in each BC organoid. In RNA‐sequencing analysis, expression levels of basal cell markers (CK5 and DSG3) and several novel genes (MMP28,CTSE,CNN3,TFPI2,COL17A1, and AGPAT4) were upregulated in BC organoids compared with normal bladder tissues or two‐dimensional (2D) BC cell lines. These established dog BC organoids might be a useful tool, not only to determine suitable chemotherapy for BC diseased dogs but also to identify novel biomarkers in human muscle‐invasive BC. In the present study, for the 1st time, dog BC organoids were generated and several specifically upregulated organoid genes were identified. Our data suggest that dog BC organoids might become a new tool to provide fresh insights into both dog BC therapy and diagnostic biomarkers.

Laser-assisted delivery of synergistic combination chemotherapy in in vivo skin

The effectiveness of topical drugs for treatment of non-melanoma skin cancer is greatly reduced by insufficient penetration to deep skin layers. Ablative fractional lasers (AFLs) are known to enhance topical drug uptake by generating narrow microchannels through the skin, but information on AFL-drug delivery in in vivo conditions is limited. In this study, we examined pharmacokinetics, biodistribution and toxicity of two synergistic chemotherapy agents, cisplatin and 5-fluorouracil (5-FU), following AFL-assisted delivery alone or in combination in in vivo porcine skin. Detected at 0-120 h using mass spectrometry techniques, we demonstrated that fractional CO₂ laser pretreatment (196 microchannels/cm², 852 μm ablation depth) leads to rapid drug uptake in 1500 μm deep skin layers, with a sixfold enhancement in peak cisplatin concentrations versus non-laser-treated controls (5 h, P = 0.005). Similarly, maximum 5-FU deposition was measured within an hour of AFL-delivery, and exceeded peak deposition in non-laser-exposed skin that had undergone topical drug exposure for 5 days. Overall, this accelerated and deeper cutaneous drug uptake resulted in significantly increased inflammatory and histopathological effects. Based on clinical scores and transepidermal water loss measurement, AFL intensified local toxic responses to drugs delivered alone and in combination, while systemic drug exposure remained undetectable. Quantitative histopathologic analyses correspondingly revealed significantly reduced epidermal proliferation and greater cellular apoptosis after AFL-drug delivery; particularly after combined cisplatin + 5-FU exposure. In sum, by overcoming the primary limitation of topical drug penetration and providing accelerated, enhanced and deeper delivery, AFL-assisted combination chemotherapy may represent a promising treatment strategy for non-melanoma skin cancer.