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, and/or 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 mg/cm3 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.

Study data collected will include pre-study demographics and measurements, treatment compliance, efficacy determined by tumor measurements, M4N levels in blood for pharmacokinetics, serum and biochemical determinations, hematology determinations, and patient vital signs.

Inclusion Criteria:

• Male and female patients ≥ 18 years of age.
• Patients with documented histologic evidence of head and neck cancer with clinically measurable disease. Head and neck cancer could have been recurrent after primary treatment with surgery, radiation therapy and/or chemotherapy.
• Measurable tumor by direct inspection, photography, or by imaging (CT scan or MRI).
• Life expectancy of at least 3 months in the Investigators' opinion.
• Negative pregnancy test if in women of childbearing potential within 1 week of starting therapy.
• Patients had provided written informed consent to participate in study.
• ECOG Performance Status of 0, 1, or 2.
• Absolute neutrophil ≥ 1500/uL, hemoglobin ≥ 8 gm%, platelets ≥ 50,000/uL,
• ALT/AST ≤ 3 x ULN (upper limit of the normal range), bilirubin ≤ 1.5 x ULN and creatinine ≤ 1.5 x ULN, PT and PTT within normal limits.

Exclusion Criteria:

• Women who were pregnant or nursing.
• Women of child bearing potential who were unwilling to use an adequate method of contraception during the course of the study.
• Treatment with prior investigational agent within 30 days of entering the study.
• Patients who are unable to comply with the study requirements.
• Patients with known sensitivity to any of the study medication components.
• Patients not consenting to photography.
• Patients with tumors that have enveloped the carotid artery or whose anatomy had been distorted such that in the Investigator's opinion present high-risk of perforation or compromise during injection.
• Prior chemotherapy, radiation therapy, or surgery for the primary carcinoma within 30 days of dosing and/or had not recovered from prior therapy toxicities.