BYL719 is an α-specific PI3K inhibitor that is synergistic and efficacious when combined with cetuximab, an FDA-approved radiosensitizing agent in the treatment of HNSCC.
Our result suggests that co-targeting of Ephs, TRKs and the c-Kit pathway may be effective at eliminating the PI3K-independent CSC population, thereby providing potential targets for future development of a novel anti-CSC therapeutic approach for HNSCC patients, particularly for patients with PIK3CA amplification.
Here, we examined the responses of a large panel of patient-derived HNSCC cell lines to various combinations of PI3K and EGFR inhibitors, including EGFR agents with varying specificity and mechanistic characteristics.
This study assessed the maximum tolerated dose (MTD) of the PI3K inhibitor buparlisib given concurrently with cetuximab in recurrent and metastatic (R/M) head and neck squamous cell carcinoma (HNSCC).
Tumor PTEN and PIK3CA/PI3K p110α were analyzed in samples from subjects treated on two trials of cetuximab-based therapy for patients with metastatic or recurrent HNSCC: E5397, a randomized trial of cisplatin plus placebo versus cisplatin plus cetuximab; and NCI-8070, a randomized trial of cetuximab plus sorafenib versus cetuximab.
PIK3CA showed a uniquely high rate of mutations within the helicase domain, and FGFR3 contained a predominance of hotspot S249C alterations that were not found in HPV- HNSCC.
Whereas overexpression of RICTOR reduced susceptibility of HNSCC tumor cells to PI3K inhibition, genetic ablation of RICTOR using CRISPR/Cas9 sensitized cells to PI3K inhibition, as well as to EGFR inhibition and cisplatin treatment.
HRAS mutant cells are resistant to PI3K inhibition and our findings suggest the involvement of a signalling intersection of the MAPK and PI3K pathways at the level of ERK-TSC2, leading to persistent mTOR activity. mTOR inhibition alone or in combination with MAPK pathway inhibition may be a promising therapeutic strategy for this subset of HNSCC tumors.
The poor prognostic value of GOF <i>TP53</i> variants and mTOR pathway upregulation was confirmed in the TCGA SCCHN cohort.<b>Conclusions:</b> Our study demonstrates a link of intratumoral heterogeneity and clonal evolution as important mechanisms of drug resistance in SCCHN and establishes mutant GOF <i>TP53</i> variants and the PI3K/mTOR pathway as molecular targets for treatment optimization.<i></i>.
Blood samples from treatment naïve HNSCC patients (<i>n</i> = 29) were interrogated for a commonly mutated PIK3CA hotspot mutation using low cost allele-specific Plex-PCR<sup>TM</sup> technology.
Our The Cancer Genome Atlas (TCGA) data analysis showed that EphB3, a receptor tyrosine kinase, is frequently coamplified with PIK3CA in head and neck squamous cell carcinoma (HNSCC).
Most importantly, one mechanism was found that PF-03084014 alone could activate the PI3K/AKT signalling, the downstream of EGFR signalling, and Erlotinib alone could activate the intracellular domain of Notch1 (NICD), while combined treatment of PF-03084014 and Erlotinib suppressed the HNSCC growth.
In present study, we investigated the resistant mechanisms and potential combination therapeutic strategy to overcome adaptive resistance to PI3K inhibitor in HNSCC.
Benign tonsils infected with high-risk HPV harbored mutations in EP300, NF1, PIK3CA, and RB1 which are considered relevant in the development of HPV-associated head and neck squamous cell carcinoma (SCC).
Combined treatment with cetuximab and MM-121 blocked EGFR and HER3 activities and inhibited the PI3K/AKT and ERK signaling pathways and HNSCC cell growth more effectively than each antibody alone.
In conclusion, this study demonstrates that P120CTN downregulation and PIK3CA mutations promote MMP1-driven invasion, providing a potential novel target for limiting metastasis in HNSCC.<b>Implications:</b> Because of its role in invasion, MMP1 represents a novel, potential target for limiting metastasis in a subset of HNSCCs with P120CTN downregulation and <i>PIK3CA</i> mutations.<i></i>.
These results can serve as a preclinical rationale for innovative treatments combining PI3K inhibition with anti-EGFR therapies and irradiation in patients with HNSCC.
Phosphatidylinositol 3-kinase (PI3K) pathway activation in squamous cell carcinoma of the head and neck contributes to treatment resistance and disease progression.