Partial Remission Without Recurrence in a 9-Year-Old Golden Retriever with Nasal Carcinoma Treated with Prednisolone/Chlorambucil Metronomic Combination Therapy: A Case Report and Literature Review of Molecular Mechanisms

Abstract

This paper reports the first case in which a hyperlipidemic retriever (due to hypothyroidism) with a nasal tumor was successfully treated—achieving partial remission—and managed using a metronomic combination of chlorambucil (3.74 mg/m², SID) and prednisolone (0.28 mg/kg, SID) orally for 9 months at a general practice. A 35 kg spayed female golden retriever aged 8 years and 8 months with nosebleeds visited the Bundang New York Animal Hospital in July 2023 after being diagnosed with nasal carcinoma. A protocol of 4 weeks of chemotherapy followed by 1 week of rest was repeated in two cycles and continued metronomically for 9 months without pause after the two cycles. The nasal exudate was significantly reduced. The size of the nasal tumor was monitored using computed tomography (CT) imaging at a referral hospital. Since the first occurrence of epistaxis, 18 months have passed (as of January 2025) and the nasal exudate is barely visible, and the vital signs and weight of the dog remain stable. The size of the nasal tumor significantly decreased after 9 months of chemotherapy completion without moderate side effects, and all the blood work was normalized, including hypercholesteremia. This study demonstrates that, in hyperlipidemic cancer patients, a prednisolone/chlorambucil metronomic combination which is cost-effective can be an alternative to tyrosine kinase inhibitors such as sorafenib, even when excluding the price. Through a literature review, the author also investigates the effect of the hyperlipidemic state on cancer, focusing on carcinoma and vascular endothelial growth factor (VEGF), as well as the RAS-RAF-MEK pathway, which is a target for tyrosine kinase inhibitors, in order to reveal the molecular mechanism of chlorambucil metronomic chemotherapy. Also, the author investigates the molecular pathway of carcinoma development in human hyperlipidemia patients through single-cell RNA sequence analysis using open public data, and discusses the molecular action of chlorambucil.