<qa>  What is the purpose of the Phase 1 dose escalation study?The purpose of this study will be to determine the safety and tolerability of intratumoral M4N. Patients suffering from cancer of the head and neck that is recurrent after primary treatment with surgery, radiation therapy, andor chemotherapy may be eligible. The design is a Phase 1 dose escalation study of M4N administered intratumorally once weekly, initially for three weeks. Dose will be escalated on the starting schedule to a target of 20 mgcm3 tumor volume and then, new patient cohorts will have their schedule extended to weekly M4N for 4 weeks. Dose escalation will continue, assuming tolerability, so that cohorts will be treated for 6 weeks, and finally, 8 weeks. 