Inhibitory effect of lomustine on the growth of spontaneous HER2-positive mammary tumors in transgenic mice

Background. In patients with HER2-positive breast cancer (HER2+ BC), as a result of targeted anti-HER2 therapy, the remission period is significantly prolonged. However, resistance to therapy often develops, especially in relation to brain metastases. In the search for effective additional drugs in combination therapy, it is advisable to study the antitumor effect of lomustine (CCNU) in HER2+ BC. Lomustine is not targeted, but is used to treat brain metastases, because it is known as one of the standard remedies for glioblastomas.

Aim. Evaluate the inhibitory activity of lomustine on the growth of spontaneous HER2+ BC in female FVB/N mice.

Materials and methods. Transgenic mice HER2+ aged 5–6 months were used, from which seven pairs of animals were selected (for control and treatment with lomustine) with spontaneous mammary tumors of the same size in each pair. Lomustine was administered once at a dose of 50 mg/kg (orally by gavage) followed by a 30-day follow-up. The criteria for evaluating the antitumor effect were ITG  % (inhibition of tumor growth), as well as TGI (tumor growth index), calculated by the ratio of the area (S) under the kinetic curve of tumor growth in the group of animals treated with lomustine (SE ) to control (SC ). With such a comparison in the control, TGI will always be 100 %.

Results. During the observation period, the volume of ВС in the control (solvent administration) increased 8-fold, while in mice treated with lomustine, the tumors regressed significantly. ITG after treatment with lomustine was 78–92 % (p = 0.007–0.0006, to control). The total mean S significantly differed by 5.6 times when comparing the control and lomustine groups and TGI in mice in the lomustine group was 18.8 %, while in the control it was 100 % (p = 0,0006).

Conclusion. Lomustine exhibits a pronounced inhibitory effect on the growth of spontaneous HER2+ ВС in FVB/N transgenic mice. The results indicate the advisability of using lomustine in patients with HER2+ ВС complicated by cerebral metastases.

1. Gheni N., Westenberg D. Quantitative real-time PCR assay with immunohistochemical evaluation of HER2/neu oncogene in breast cancer patients and its correlation with clinicopathological findings. Indian J Pathol Microbiol 2020;63(Suppl.):S.123–8. DOI: 10.4103/IJPM.IJPM_136_19

2. Zimmer A.S., Van Swearingen A.E.D., Anders C.K. HER2-positive breast cancer brain metastasis: A new and exciting landscape. Cancer Rep (Hoboken) 2022;5(4):e1274. DOI: 10.1002/cnr2.1274

3. Kunte S., Abraham J., Montero A.J. Novel HER2-targeted therapies for HER2-positive metastatic breast cancer. Cancer 2020;126(19):4278–88. DOI: 10.1002/cncr.33102

4. Tyulyandin S.A., Artamonova E.V., Zhukova L.G. et al. Practical recommendations for the drug treatment of breast cancer. Zlokachestvennye opukholi = Malignant Tumors: Practice Guidelines RUSSCO #3s2 2022;12:155–97. (In Russ.). DOI: 10.18027/2224-5057-2022-12-3s2-155-197

5. Bredin P., Walshe J.M., Denduluri N. Systemic therapy for metastatic HER2-positive breast cancer. Semin Oncol 2020;47(5):259–69. DOI: 10.1053/j.seminoncol.2020.07.008

6. Weller M., Le Rhun E. How did lomustine become standard of care in recurrent glioblastoma? Cancer Treat Rev 2020;87:102029. DOI: 10.1016/j.ctrv.2020.102029

7. Panchenko A.V., Popovich I.G., Trashkov A.P. et al. Biomarkers of aging, life span and spontaneous carcinogenesis in the wild type and HER-2 transgenic FVB/N female mice. Biogerontology 2016;17(2):317–24. DOI: 10.1007/s10522-015-9611-y

8. Stukov A.N., Ivanova M.A., Nikitin A.K. et al. Tumor growth index as an integral criterion for the effectiveness of antitumor therapy in the experiment. Voprosy onkologii = Issues of oncology 2001;47(5):616–8 (In Russ.). PMID: 11785106

9. Duan F., Simeone S., Wu R. et al. Area under the curve as a tool to measure kinetics of tumor growth in experimental animals. J Immunol Methods 2012;382(1-2):224–8. DOI: 10.1016/j.jim.2012.06.005

10. Holder D.J., Hsuan F., Dixit R., Soper K. A method for estimating and testing area under the curve in serial sacrifice, batch, and complete data designs. J Biopharm 1999;9(3):451–64. DOI: 10.1081/BIP-100101187

11. Weiss R.B., Issell B.F. The nitrosoureas: carmustine (BCNU) and lomustine (CCNU). Cancer Treat Rev 1982;9(4):313–30. DOI: 10.1016/s0305-7372(82)80043-1

12. Lee F.Y., Workman P., Roberts J.T., Bleehen N.M. Clinical pharmacokinetics of oral CCNU (lomustine). Cancer Chemother Pharmacol 1985;14(2):125–31. DOI: 10.1007/BF00434350

13. Stukov A.N., Vershinina S.F., Koziavin N.A. et al. Study of the effect of lomustin on HER2-positive breast cancer in FVB/N HER-2 transgenic mice. Sibirskiy onkologicheskiy zhurnal = Siberian Journal of Oncology 2019;18(5):54–60 (In Russ.). DOI: 10.21294/1814-4861-2019-18-5-54-60

14. Cruz-Muñoz W., Kerbel R.S. Preclinical approaches to study the biology and treatment of brain metastases. Semin Cancer Biol 2011;21(2):123–30. DOI: 10.1016/j.semcancer.2010.12.001

15. Fisusi F.A., Siew A., Chooi K.W. et al. Lomustine nanoparticles enable both bone marrow sparing and high brain drug levels – A strategy for brain cancer treatments. Pharm Res 2016;33(5):1289–303. DOI: 10.1007/s11095-016-1872-x

16. Mineo J.F., Bordron A., Quintin-Roué I. et al. Recombinant humanised anti-HER2/neu antibody (Herceptin) induces cellular death of glioblastomas. Br J Cancer 2004;91(6):1195–9. DOI: 10.1038/sj.bjc.6602089

17. Cui H., Cheng Y., Piao S.Z. et al. Correlation between HER-2/ neu(erbB-2) expression level and therapeutic effect of combination treatment with HERCEPTIN and chemotherapeutic agents in gastric cancer cell lines. Cancer Cell Int 2014;14(1):10. DOI: 10.1186/1475-2867-14-10

18. Lewis Phillips G.D., Nishimura M.C., Lacap J.A. et al. Trastuzumab uptake and its relation to efficacy in an animal model of HER2-positive breast cancer brain metastasis. Breast Cancer Res Treat 2017;164(3):581–91. DOI: 10.1007/s10549-017-4279-4

19. Fry E.A., Taneja P., Inoue K. Clinical applications of mouse models for breast cancer engaging HER2/neu. Integr Cancer Sci Ther 2016;3(5):593–603. DOI: 10.15761/ICST.1000210

20. Provinciali M., Re F., Donnini A. et al. Effect of resveratrol on the development of spontaneous mammary tumors in HER-2/ neu transgenic mice. Int J Cancer 2005;115(1):36–45. DOI: 10.1002/ijc.20874

21. Anisimov V.N., Khavinson V.K., Provinciali M. et al. Inhibitory effect of the peptide epitalon on the development of spontaneous mammary tumors in HER-2/neu transgenic mice. Int J Cancer 2002;101(1):7–10. DOI: 10.1002/ijc.10570

22. Anisimov V.N., Berstein L.M., Egormin P.A. et al. Effect of metformin on life span and on the development of spontaneous mammary tumors in HER-2/neu transgenic mice. Exp Gerontol 2005;40(8-9):685–93. DOI: 10.1016/j.exger.2005.07.007

23. Anisimov V.N., Alimova I.N., Baturin D.A. et al. The effect of melatonin treatment regimen on mammary adenocarcinoma development in HER-2/neu transgenic mice. Int J Cancer 2003;103(3):300–5. DOI: 10.1002/ijc.10827

24. Al Rabadi L., Bergan R. A way forward for cancer chemoprevention: Think local. Cancer Prev Res (Phila) 2017;10(1):14–35. DOI: 10.1158/1940-6207.CAPR-16-0194