 I. To determine the safety and recommended phase II dose RP2D of AT13387 Hsp90 inhibitor AT13387 in combination with concurrent cisplatin and radiotherapy in patients with locoregionally advanced squamous cell carcinoma of the head and neck LA-SCCHN. Dose Escalation Phase II. To preliminarily evaluate the safety and preliminary efficacy of AT13387 in combination with concurrent cisplatin and radiotherapy in patients with LA-SCCHN. Dose Expansion Phase 