Doxorubicin Conjugation to Reovirus Improves Oncolytic Efficacy in Triple-Negative Breast Cancer

Abstract

Breast cancer is the second leading cause of cancer-related deaths in women in the United States. The triple-negative breast cancer (TNBC) subtype associates with higher rates of relapse, shorter overall survival, and aggressive metastatic disease. Hormone therapy is ineffective against TNBC, leaving patients with limited therapeutic options. Mammalian orthoreovirus (reovirus) preferentially infects and kills transformed cells, and a genetically engineered reassortant reovirus infects and kills TNBC cells more efficiently than prototypical strains. Reovirus oncolytic efficacy is further augmented by combination with topoisomerase inhibitors, including the frontline chemotherapeutic doxorubicin. However, long-term doxorubicin use correlates with toxicity to healthy tissues. Here, we conjugated doxorubicin to reovirus (reo-dox) to control drug delivery and enhance reovirus-mediated oncolysis. Our data indicate that conjugation does not impair viral biology and enhances reovirus oncolytic capacity in TNBC cells. Reo-dox infection promotes innate immune activation, and crosslinked doxorubicin retains DNA-damaging properties within infected cells. Importantly, reovirus and reo-dox significantly reduce primary TNBC tumor burden in vivo , with greater reduction in metastatic burden after reo-dox inoculation. Together, these data demonstrate that crosslinking chemotherapeutic agents to oncolytic viruses facilitates functional drug delivery to cells targeted by the virus, making it a viable approach for combination therapy against TNBC.

Systematic Pan-Cancer Population-Based Analysis Reveals the Incidence and Prognosis of Lung Metastases at Diagnosis

“…HR − /HER2 + and triple-negative breast cancer patients have the highest incidence of metastasis. Triple-negative patients have poor survival and usually respond poorly to hormonal therapy [16]. Recently, more attention has been paid to the underlying molecular mechanisms that play an important Journal of Oncology 5 role in the organ-specific metastasis of breast cancer cells [15].…”

Oncolytic Virotherapy Treatment of Breast Cancer: Barriers and Recent Advances

“…However, promising pre-clinical investigations are currently being conducted to help overcome this. Berry et al [36] developed a doxorubicin conjugation reovirus (re-dox) for controlled drug release whilst simultaneously enabling viral lysis of tumour cells for the treatment of TNBC. The group used a hetero-bifunctional crosslinker (succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate), which enables covalent bonds to form between the doxorubicin and virus, and enables the simultaneous release of viral particles and doxorubicin within the tumour after intratumoural administration.…”

“…The results demonstrated in vitro show that the combination therapy increased mRNA expression of innate immune activation markers, including interferon-IFNL1, IFNB1, and IFNG in MDA-MB-231 cells-whereas treatment with re-dox still retained its infection and DNAdamaging abilities. Re-dox also significantly reduced tumour burden in mice with TNBC (4T1 model) implanted in the hind flank, resulting in a reduction in metastatic disease, predominantly within the lungs [36]. In addition, Bourgeois-Daigneault et al looked at the combination of oncolytic rhabdovirus Maraba-MG1 and paclitaxel for the treatment of murine TNBC in two established cell lines, 4T1 and E0771, in vitro and in vivo [12].…”

Combining Oncolytic Viruses and Small Molecule Therapeutics: Mutual Benefits

“…This was further enhanced with additional co-treatment of the cyclophosphamide analogue ifosfamide [224]. Alternatively, the co-application of doxorubicin can also promote an increased infectivity of tumor cells by oncolytic viruses such as certain reovirus strains [225,226]. A more complex interplay has also been reported, where OV treatment induces the nuclear translocation of the cytoplasmic transcription factor cAMP response element-binding protein 3-like 1 (CREB3L1) [227], which in turn is associated with augmented doxorubicin-mediated cell death [228].…”