ABSTRACT
BACKGROUND: Head and neck squamous cell carcinomas (HNSCCs) are among the most abundant malignancies worldwide. Patients with recurrent/metastatic disease undergo combination chemotherapy containing cetuximab, the monoclonal antibody used against the epidermal growth factor receptor (EGFR). Cetuximab augments the effect of chemotherapy; however, a significant number of patients show therapy resistance. The mechanism of resistance is yet to be unveiled, although extracellular alterations of the receptor have been reported, and their role in cetuximab failure has been proposed. AIMS: Here, we investigate possible effects of the multi-exon deletion variant (EGFRvIII), and the single nucleotide polymorphism EGFR R521K on cetuximab efficacy. RESULTS: Our results show that in HNSCC patients, the EGFRvIII allele frequency is under 1%; therefore, it cannot lead to common resistance. EGFR R521K, present in 42% of the patients, is investigated in vitro in four HNSCC cell lines (two wild-type and two heterozygous for EGFR R521K). While no direct effect is found to be related to the EGFR status, cells harboring R521K show a reduced sensitivity in ADCC experiments and in vivo xenograft experiments. However, this preclinical difference is not reflected in the progression-free or overall survival of HNSCC patients. Furthermore, NK cell and macrophage presence in tumors is not related to EGFR R521K. DISCUSSION: Our results suggest that EGFR R521K, unlike reported previously, is unable to cause cetuximab resistance in HNSCC patients; therefore, its screening before therapy selection is not justifiable.
ABSTRACT
Head and neck squamous cell carcinomas (HNSCC) take many lifes worldwide. Patients with recurrent/metastatic disease receive combination chemotherapy containing anti-EGFR antibody cetuximab. However, resistance often hurdles therapy. The mechanism is yet to unveil, although EGFR extracellular alterations and activity of c-Met signaling were accused. We investigated the effects of EGFR-vIII and EGFR-R521K on cetuximab efficacy in HNSCC in cellular, xenograft, and clinical setup. Furthermore, we investigated the efficacy of c-Met inhibition in HNSCC in vitro and in vivo. We showed that EGFR-vIII is very rare in HNSCC, while the common R521K polymorphism abolishes antibody-dependent cellular cytotoxicity and in vivo antitumor effect of cetuximab. This selectivity was not reflected in immunophenotype or survival data of HNSCC patients, suggesting a more complex mechanism behind. Interestingly, c-Met inhibitor SU11274 was more effective in cetuximab-resistant, EGFR R521K heterozygous cells and xenografts, raising the possible importance of simultaneous targeting of the two receptors.
Subject(s)
Carcinoma, Squamous Cell , Head and Neck Neoplasms , Carcinoma, Squamous Cell/drug therapy , Carcinoma, Squamous Cell/genetics , Cell Line, Tumor , Cetuximab/pharmacology , Drug Resistance, Neoplasm , ErbB Receptors/genetics , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/genetics , Humans , Squamous Cell Carcinoma of Head and Neck/drug therapy , Squamous Cell Carcinoma of Head and Neck/genetics , Xenograft Model Antitumor AssaysABSTRACT
The standard treatment of papillary microcarcinomas (mPTC; ≤1 cm) regardless of their size, was similar to the advanced ones till the recent past: immediate surgery ± radioactive iodine (RAI) therapy. However, the American Thyroid Association (ATA) 2015 guidelines accept the active surveillance in selected cases. We performed a retrospective analysis on the clinical data of 103 patients with PTmC in a single (62.1%) or multiple nodes (37.9%), treated with immediate surgery followed in most cases by postoperative RAI between 2001 and 2010. N stage of the neck was pN0 in 81, and pN+ in 22 patients. Survival probability was significantly related to age (p<0.001), TSH level (p=0.0347), N stage (p=0.0402) and need for neck dissection (p=0.0045). Overall survival at 5, 10, and 15 years was 95%, 89%, and 86%, while disease-specific mortality at 5 and 10 years was 3% and 5%, respectively. Our data show that immediate radical surgery with or without postoperative RAI yielded long-term survival similar to those published. Nevertheless, progression affecting mostly older men was not prevented by immediate surgery. Our findings do not contradict the acceptability of active surveillance recommended by the 2015 ATA Guidelines.
