Supplementary Figures S1-S6. Supplementary Fig. S1. The effect of cyclophosphamide on liposome delivery is dose dependent, requires a predose rather than a co-injection, and is not mediated by changes in blood clearance. Supplementary Fig. S2. Cyclophosphamide induces DNA-damage and tumor cell apoptosis. Supplementary Fig. S3. Effects of cyclophosphamide, ifosfamide, paclitaxel and eribulin on HER2-tPLD delivery, stromal cell density, total cell density, and interstitial space area. Supplementary Fig. S4. Pretreatment of tumors with cyclophosphamide significantly enhances nuclear delivery of doxorubicin following HER2-tPLD injection. Supplementary Fig. S5. Pretreatment of tumors with cyclophosphamide enhances the delivery of HER2-tPLD in multiple tumor models. Supplementary Fig. S6. The combination of a cyclophosphamide predose with HER2-tPLD results in synergistic anti-tumor activity.
ARTICLE ABSTRACTGiven the bulky nature of nanotherapeutics relative to small molecules, it is hypothesized that effective tumor delivery and penetration are critical barriers to their clinical activity. HER2-targeted PEGylated liposomal doxorubicin (MM-302, HER2-tPLD) is an antibody–liposomal drug conjugate designed to deliver doxorubicin to HER2-overexpressing cancer cells while limiting uptake into nontarget cells. In this work, we demonstrate that the administration and appropriate dose sequencing of cyclophosphamide can improve subsequent MM-302 delivery and enhance antitumor activity in preclinical models without negatively affecting nontarget tissues, such as the heart and skin. We demonstrate that this effect is critically dependent on the timing of cyclophosphamide administration. Furthermore, the effect was found to be unique to cyclophosphamide and related analogues, and not shared by other agents, such as taxanes or eribulin, under the conditions examined. Analysis of the cyclophosphamide-treated tumors suggests that the mechanism for improved MM-302 delivery involves the induction of tumor cell apoptosis, reduction of overall tumor cell density, substantial lowering of interstitial fluid pressure, and increasing vascular perfusion. The novel dosing strategy for cyclophosphamide described herein is readily translatable to standard clinical regimens, represents a potentially significant advance in addressing the drug delivery challenge, and may have broad applicability for nanomedicines. This work formed the basis for clinical evaluation of cyclophosphamide for improving liposome deposition as part of an ongoing phase I clinical trial of MM-302 in HER2-positive metastatic breast cancer. Mol Cancer Ther; 14(9); 2060–71. ©2015 AACR.