Rapalogs induce non-apoptotic, autophagy-dependent cell death in HPV-negative TP53 mutant head and neck squamous cell carcinoma.

TP53 is the most frequently mutated gene in head and neck squamous cell carcinoma (HNSCC). Patients with HPV-negative TP53 mutant HNSCC have the worst prognosis, necessitating additional agents for treatment. Since mutant p53 causes sustained activation of the PI3K/AKT/mTOR signaling pathway, we investigated the effect of rapalogs RAD001 and CCI-779 on HPV-negative mutTP53 HNSCC cell lines and xenografts. Rapalogs significantly reduced cell viability and colony formation. Interestingly, rapalogs-induced autophagy with no effect on apoptosis. Pretreatment with autophagy inhibitors, 3-methyladenine (3-MA) and ULK-101 rescued the cell viability by inhibiting rapalog-induced autophagy, suggesting that both RAD001 and CCI-779 induce non-apoptotic autophagy-dependent cell death (ADCD). Moreover, rapalogs upregulated the levels of ULK1 and pULK1 S555 with concomitant downregulation of the mTORC1 pathway. However, pretreatment of cells with rapalogs prevented the ULK-101-mediated inhibition of ULK1 to sustained autophagy, suggesting that rapalogs induce ADCD through the activation of ULK1. To further translate our in vitro studies, we investigated the effect of RAD001 in HPV-negative mutTP53 (HN31 and FaDu) tumor cell xenograft model in nude mice. Mice treated with RAD001 exhibited a significant tumor volume reduction without induction of apoptosis, and with a concomitant increase in autophagy. Further, treatment with RAD001 was associated with a considerable increase in pULK1 S555 and ULK1 levels through the inhibition of mTORC1. 3-MA reversed the effect of RAD001 on FaDu tumor growth suggesting that RAD001 promotes ACDC in HPV-negative mutTP53 xenograft. This is the first report demonstrating that rapalogs promote non-apoptotic ADCD in HPV-negative mutTP53 HNSCC via the ULK1 pathway. Further studies are required to establish the promising role of rapalogs in preventing the regrowth of HPV-negative mutTP53 HNSCC.

Pilot Study: Pneumatic Compression Garment Therapy for Postradiotherapy Laryngopharyngeal Edema.

OBJECTIVES: Pneumatic compression garment therapy (PCGT) has been established as treatment for postradiotherapy lymphedema, and its use in head and neck patients is becoming more common. Although effects on interstitial edema of the cervical soft tissues have been studied, effects on internal laryngopharyngeal edema, as well as associated symptoms of dysphagia and dysphonia, have yet to be published. METHODS: We surveyed 7 patients treated with radiation for head and neck cancer (HNC) who had also been prescribed PCGT for cervical lymphedema. Patients were asked about subjective experience with the device, and also administered the Eating Assessment Tool-10 (EAT-10) and Voice Handicap Index-10 (VHI-10) surveys regarding their symptoms after using PCGT. Laryngoscopy videos from these same periods were also reviewed and scored using a validated tool for assessing laryngopharyngeal edema. RESULTS: 85% of patients reported at least some improvement in dysphagia and dysphonia following PCGT. Average EAT-10 score after PCGT was 11.4 and average VHI-10 score after PCGT was 8.7. These compare more favorably to historical scores for the same questionnaires in similar patient populations. Laryngeal edema scores on endoscopic examination were not significantly different after at least 3 months of therapy (pre: 20.15, post: 20.21, P = .975); however, the utility of this result is limited by a low inter-rater reliability (Krippendorff α = .513). CONCLUSIONS: While we are unable to show any difference in objective assessment of laryngopharyngeal edema on endoscopic examination in this small pilot study, patients report substantial subjective improvement in postradiotherapy dysphagia and dysphonia following cervical PCGT that warrants more formal investigation.