Preclinical and clinical evaluation of intraductally administered agents in early breast cancer

Abstract

Most breast cancers originate in the epithelial cells lining the breast ducts. Intraductal administration of cancer therapeutics would lead to high drug exposure to ductal cells and eliminate preinvasive neoplasms while limiting systemic exposure. We performed preclinical studies in N-methyl-N'-nitrosourea-treated rats to compare the effects of 5-fluorouracil, carboplatin, nanoparticle albumin-bound paclitaxel, and methotrexate to the previously reported efficacy of pegylated liposomal doxorubicin (PLD) on treatment of early and established mammary tumors. Protection from tumor growth was observed with all five agents, with extensive epithelial destruction present only in PLD-treated rats. Concurrently, we initiated a clinical trial to establish the feasibility, safety, and maximum tolerated dose of intraductal PLD. In each eligible woman awaiting mastectomy, we visualized one ductal system and administered dextrose or PLD using a dose-escalation schema (2 to 10 mg). Intraductal administration was successful in 15 of 17 women with no serious adverse events. Our preclinical studies suggest that several agents are candidates for intraductal therapy. Our clinical trial supports the feasibility of intraductal administration of agents in the outpatient setting. If successful, administration of agents directly into the ductal system may allow for "breast-sparing mastectomy" in select women.

Trial registration: ClinicalTrials.gov NCT00290732.

Figures

Fig. 1

Preclinical analysis of intraductal therapy of MNU-induced rat mammary tumors. (A) Ductal branching structure density in representative hematoxylin-stained whole mounts (top panel, ×10 magnification) of the fourth mammary gland of an uninjected rat (None) and an intraductal PLD-injected rat 7 weeks after treatment. Examination at higher power (100) of the whole mount of the mammary gland after intraductal treatment with 5-FU, carboplatin (CBD), methotrexate (MTX), nab-paclitaxel (ABX), PLD, or None. Bottom panel, H&E-stained sections of formalin-fixed, paraffin-embedded mammary glands after treatment with 5-FU, carboplatin, methotrexate, nab-paclitaxel, PLD, or None. Top panel scale bars, 2 mm (×10) or 200 μm (×100). H&E scale bars, 50 μm. (B) Percentage of Ki-67–positive cells after intraductal drug or saline treatment. Data are averages ± SEM (n = 5 rats per treatment group). *P < 0.05; ***P < 0.0001 by ANOVA with multiple comparisons adjusted with Tukey’s procedure. (C) Mammary gland tumor-free survival in response to intraductal chemotherapy. Female rats received MNU (week 0), and drug was administered intraductally 2 weeks later. Rats were killed 22 weeks after start of treatment. (D) Mammary gland tumor-free survival in response to intraductal 5-FU therapy. Female rats received MNU (week 0); 2 weeks later, the rats were left untreated or treated with 5-FU intravenously or intraductally. In each rat, only four mammary glands received 5-FU, whereas eight mammary glands remained untreated. Rats were killed 22 weeks after start of treatment. (E) Growth of MNU-induced mammary tumors (in mm3) over 6 weeks after treatment of a single palpable tumor with either intraductal or intravenous 5-FU. Rats received treatment four times at weekly intervals. Data are means ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001, using a mixed-effects model.

Fig. 2

Representative ductogram and histopathology images from the clinical trial. (A) A ductogram from a 29-year-old participant, which outlines dilated ducts surrounding the area of the tumor, located in the upper aspect of the right breast (arrow). (B) A ductogram from a 37-year-old participant. The ductogram outlines a normal branching duct coursing superior to the site of malignant calcifications in the tail of the left breast. (C) A histological specimen of a prophylactic mastectomy representing a treated lobule (blue-dyed region). (D) Histological specimen of the same prophylactic mastectomy shown in (C) of a non-treated region (non-blue-dyed region). Scale bars, 100 μm.