Repurposing Drugs in Small Animal Oncology

Repurposing drugs in oncology consists of using off-label drugs that are licensed for various non-oncological medical conditions to treat cancer. Repurposing drugs has the advantage of using drugs that are already commercialized, with known mechanisms of action, proven safety profiles, and known toxicology, pharmacokinetics and pharmacodynamics, and posology. These drugs are usually cheaper than new anti-cancer drugs and thus more affordable, even in low-income countries. The interest in repurposed anti-cancer drugs has led to numerous in vivo and in vitro studies, with some promising results. Some randomized clinical trials have also been performed in humans, with certain drugs showing some degree of clinical efficacy, but the true clinical benefit for most of these drugs remains unknown. Repurposing drugs in veterinary oncology is a very new concept and only a few studies have been published so far. In this review, we summarize both the benefits and challenges of using repurposed anti-cancer drugs; we report and discuss the most relevant studies that have been previously published in small animal oncology, and we suggest potential drugs that could be clinically investigated for anti-cancer treatment in dogs and cats.

Impact of beta blockers on epithelial ovarian cancer survival

OBJECTIVE

Stress may promote ovarian cancer progression through mechanisms including autonomic nervous system mediators such as norepinephrine and epinephrine. Beta blockers, used to treat hypertension, block production of these adrenergic hormones, and have been associated with prolonged survival in several malignancies. We sought to determine the association between beta blocker use and epithelial ovarian cancer (EOC) disease progression and survival.

METHODS

We performed an institutional retrospective review of patients with EOC treated between 1996 and 2006. Patients underwent cytoreductive surgery followed by platinum-based chemotherapy. Women were considered beta blocker users if these medications were documented on at least two records more than 6 months apart. Statistical tests included Fisher's exact, Kaplan-Meier, and Cox regression analyses.

RESULTS

248 met inclusion criteria. 68 patients used antihypertensives, and 23 used beta blockers. Median progression-free survival for beta blocker users was 27 months, compared with 17 months for non-users (p=0.05). Similarly, overall disease-specific survival was longer for beta blocker users (56 months) compared with non-users (48 months, p=0.02, hazard ratio=0.56). Multivariate analysis identified beta blocker use as an independent positive prognostic factor, after controlling for age, stage, grade, and cytoreduction status (p=0.03). Overall survival remained longer for beta blocker users (56 months) when compared with hypertensive patients on other medications (34 months) and patients without hypertension (51 months) (p=0.007).

CONCLUSIONS

In this cohort of patients with EOC, beta blocker use was associated with a 54% reduced chance of death compared with that of non-users.