Abstract 2069: Combination of mTOR targeting with cetuximab and conventional chemotherapy: a preclinical study on an orthotopic xenograft model of head and neck cancer.
Authors: Bozec Alexandre , Ebran Nathalie , Monteverde Martino , Toussan Nicolas , Cayre Anne , Etienne-Grimaldi Marie-Cristine , Lo Nigro Cristiana , Sudaka Anne , Merlano Marco , Penault-Llorca Frederique , Milano Gerard 
Published: August 2014

Background: Preclinical and clinical studies on head and neck squamous cell carcinoma (HNSCC) demonstrated synergistic anti-tumoral effects when combining anti-EGFR agents with conventional chemotherapeutic drugs such as cisplatin (C) and 5-fluorouracil (F). In a previous experimental study, our group pointed out an enhancement of PIK3CA signaling (pAKT) in tumors re-growing after cetuximab-based treatment (Bozec et al. Br J Cancer 2007). This context justifies investigations on mTOR inhibitors combined with cetuximab (Cetux) in HNSCC.

Methods: The effects on tumor growth of treatments combining an mTOR inhibitor (Temsirolimus (Tem)), an anti-EGFR (Cetux) and a clinically validated-chemotherapeutic regimen (C+F) were examined in an orthotopic (floor of the mouth) model of human HNSCC (CAL33 cell line, over-expressing EGFR, secreting VEGF-A, H1047R PIK3CA mutated). In parallel, in-vitro experiments were conducted in order to strengthen the data arising from the in-vivo study. On day 0, cells were injected in nude NMRI mice. Treatment was started on day 3 and consisted of 8 groups (10 mice/group) treated as follows: Control, Tem (5 mg/kg i.p. five times a week), Cetux (2.5 mg/kg i.p. once a week), cisplatin (6 mg/kg) + 5-fluorouracil (17 mg/kg) (i.p. once a week), concomitant treatment combining Tem with either Cetux, C+F, or Cetux+C+F. The tumor growth was recorded by IVIS imaging and on day 13 after animal euthanasia with a caliper ruler.

Results: All tested treatments produced significant growth inhibition as compared to controls (p&lt;0.01). The Tem-Cetux and Tem-Cetux+C+F regimens produced the strongest growth-inhibiting effects, however the addition of C+F to the Tem-Cetux regimen did not result in a significantly greater effect as compared to Tem-Cetux (p = 0.18). The growth-inhibiting effects of Tem-Cetux were significantly stronger than those of Tem or Cetux alone (p&lt;0.004). Moreover, a significant synergism was demonstrated between Temsirolimus and Cetuximab effects (significant interaction: p = 0.001, ANOVA). Furthermore, in contrast to mice receiving the Tem-Cetux+C+F regimen, mice treated with Tem-Cetux had no clinical signs of secondary effects. Accordingly, the mice weight loss measured on day 12 was significantly lower in mice receiving Tem-Cetux regimens as compared to mice receiving the Tem-Cetux+C+F regimen (p=0.005). IHC analysis on tumor vasculature (VEGFR2), proliferation status (Ki67) and downstream signaling phospho-proteins (pAKT, p-P70/S6k, pERK) strengthen our data on tumor growth and proliferation.

Conclusion: These data on the association of temsilorimus with cetuximab could serve as a strong basis for innovative treatments aiming at an optimal management of patients with recurrent/metastatic HNSCC.

Citation Format: Alexandre Bozec, Nathalie Ebran, Martino Monteverde, Nicolas Toussan, Anne Cayre, Marie-Cristine Etienne-Grimaldi, Cristiana Lo Nigro, Anne Sudaka, Marco Merlano, Frederique Penault-Llorca, Gerard Milano. Combination of mTOR targeting with cetuximab and conventional chemotherapy: a preclinical study on an orthotopic xenograft model of head and neck cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2069. doi:10.1158/1538-7445.AM2013-2069