Targeted Therapy with PI3K, PARP, and WEE1 Inhibitors and Radiotherapy in HPV Positive and Negative Tonsillar Squamous Cell Carcinoma Cell Lines Reveals Synergy while Effects with APR-246 Are Limited

Abstract

Human papillomavirus positive (HPV+) tonsillar and base of tongue cancer (TSCC/BOTSCC) is rising in incidence, but chemoradiotherapy is not curative for all. Therefore, targeted therapy with PI3K (BYL719), PARP (BMN-673), and WEE1 (MK-1775) inhibitors alone or combined was pursued with or without 10 Gy and their effects were analyzed by viability, proliferation, and cytotoxicity assays on the TSCC/BOTSCC cell lines HPV+ UPCI-SCC-154 and HPV− UT-SCC-60A. Effective single drug/10 Gy combinations were validated on additional TSCC lines. Finally, APR-246 was assessed on several TSCC/BOTSCC cell lines. BYL719, BMN-673, and MK-1775 treatments induced dose dependent responses in HPV+ UPCI-SCC-154 and HPV− UT-SCC-60A and when combined with 10 Gy, synergistic effects were disclosed, as was also the case upon validation. Using BYL719/BMN-673, BYL719/MK-1775, or BMN-673/MK-1775 combinations on HPV+ UPCI-SCC-154 and HPV− UT-SCC-60A also induced synergy compared to single drug administrations, but adding 10 Gy to these synergistic drug combinations had no further major effects. Low APR-246 concentrations had limited usefulness. To conclude, synergistic effects were disclosed when complementing single BYL719 BMN-673 and MK-1775 administrations with 10 Gy or when combining the inhibitors, while adding 10 Gy to the latter did not further enhance their already additive/synergistic effects. APR-246 was suboptimal in the present context.

Combination of PARP and WEE1 inhibitors in vitro: Potential for use in the treatment of SHH medulloblastoma

“…Combined treatment with MK-1775 and BMN673 exerted synergistic effects on both cell lines and further decreased the proportion of cells in the G1 and S phases, and increased the number of cells in the G2/M phase. Of note, combined treatment in both cell lines resulted in a clear increase in the proportion of cells in the >G2 phase; this is not surprising, as previous studies on MK-1775 have suggested that WEE1 inhibition causes an impairment in cytokinesis, leading to tetraploid cells (55). This needs to be examined further in order to validate the obtained results.…”

“…The concentration-dependent effects which were observed on the MB cell lines with single MK-1775 treatments were expected, since this has been previously demonstrated with corresponding inhibitors on MB and other tumor cell lines, such as head and neck cancer (46,(52)(53)(54)(55).…”

“…Nevertheless, of note, the obtained data demonstrate that drug-drug interactions using WEE1 and PARP inhibitors are complex and can result in either synergistic or antagonistic interactions, depending on the MB subgroup profile and the mutation profile of the different cell lines. While broader concentration ranges and modified incubated periods may shed further light on the drug interactions with respect to their antitumor efficacy, the concentrations used herein adhere to commonly used standard conditions, and therefore allow for more direct comparisons (47,55).…”

Assessment of the Mutation Profile of Tonsillar Squamous Cell Carcinomas Using Targeted Next-Generation Sequencing

“…As the TP53 gene is widely inactivated for its tumor-suppressive function in a number of cancers, and TP53 mutation has been reported to confer resistance to cancer therapies, its reactivation or restoration may be a highly attractive therapeutic target for treating the disease, resulting in tumor regression [ 28 ]. Unfortunately, this trial is generally regarded as difficult and has only been demonstrated in animal and cell line models [ 29 , 30 , 31 ]. Synergistic effects have been displayed in the TSCC cell line when complementing single PI3K, PARP, and WEE1 inhibitor medications with 10 Gy or combining these inhibitors [ 31 ].…”

“…Unfortunately, this trial is generally regarded as difficult and has only been demonstrated in animal and cell line models [ 29 , 30 , 31 ]. Synergistic effects have been displayed in the TSCC cell line when complementing single PI3K, PARP, and WEE1 inhibitor medications with 10 Gy or combining these inhibitors [ 31 ]. In a current Phase I clinical trial, the WEE1 kinase inhibitor adavosertib (AZD1775) has exhibited beneficials effects on TP53 mutants in the context of HNSCC [ 32 ].…”