The intraductal injection of 5-fluorouracil for breast cancer: Preventive effect and immune response.

Abstract

e13559 Background: Chemotherapy has been shown to act as an immune response modifier. Many groups are using chemotherapy to induce immune responses such as by using low doses of cyclophosphamide. Building up on our previous work (Murata et al., 2006, Stearns et al., 2011), we demonstrate that intraductal (i.duc), but not the intravenous (IV) route of injection of chemotherapy to HER2/neu transgenic mouse mammary glands (MMG) alters the tumor environment to effectively induce immune effector cells. Methods: 1.Tumor-free survival: 5-fluorouracil (5FU) was administered intraductally to the MMGs on the left side of mice; the MMG on right side were untreated. 2. FACS analysis: 20w mice were administered 5FU 2 times in a 4 week interval i.duc only to the left side, IV, or no treatment (NT). At week 5, the mice were sacrificed and the regional lymph nodes (RLN) and spleen were removed. Lymphocytes from RLN and spleen were analyzed. 3. Tumor re-challenge: GT8 cancer cells were injected into the one side of 4th mammary gland fat pad of 12 week mice. The mice were then injected i.duc with 5-FU to all teats in the tumor implanted side, or IV or given NT. The surviving mice were re-challenged with GT8 cancer cells into the ipsilateral 3rd mammary gland fat pad, 4 weeks after the first inoculation. Results: 1. The tumor incidence in the 5FU treated side after 16 weeks was significantly lower (13% of 70 glands) compared to mice that received NT (34% of 150, p=0.001), and IV (28% of 70, p=0.03). The tumor incidence in the untreated side of 5FU-treated mice was also significantly lower (18% of 70) compared to the NT (p=0.01). 2. The number of CD8 T cell showed no change among the groups in the RLN but was significantly lower (p=0.01) in the spleen of the i.duc. The number of CD62LLOW+ T cell in treated side of RLN was significantly higher compared to the IV (p=0.02) and NT (p=0.02). The number of CD62LLOW+ was low in the spleen. 3. The survivors in the group previously treated with i.duc 5-FU were able to achieve a lasting rejection of the tumor re-challenge when compared to mice who previously received 5-FU IV. Conclusions: I.duc administration of 5FU into MMG effectively induced immune effector cells and prevented mammary tumor growth in HER2/neu transgenic mice.