This is a prospective, open-label, single arm, non-randomized study of RiMO-301 with hypofractionated radiation and a PD-1 Inhibitor in patients with unresectable, recurrent or metastatic head-neck cancer.

Primary Objectives:

• To determine the tolerability of RiMO-301 with hypofractionated X-ray radiotherapy and a PD-1 inhibitor (pembrolizumab or nivolumab) in patients with unresectable, recurrent or metastatic head-neck cancer
• To determine the efficacy of RiMO-301 with hypofractionated X-ray radiotherapy and a PD-1 inhibitor (pembrolizumab or nivolumab)

Secondary Objectives:

• To evaluate progression-free survival for up to 12 months
• To determine overall survival for up to 24 months
• To assess patient quality of life

The target population is patients with unresectable, recurrent or metastatic head-neck cancer which is clinically accessible to intratumoral injection.

Inclusion Criteria:

• Diagnosis of head-neck cancer that requires palliative radiotherapy

• Patients with unresectable, recurrent or metastatic HNSCC, regardless if the patients have progressed on or are intolerant to platinum-based chemotherapy prior to study enrollment or if the patients are receiving pembrolizumab in the first line:

  • receiving a PD-1 inhibitor (pembrolizumab or nivolumab) as a standard of care, or
  • suitable to receive a PD-1 inhibitor (pembrolizumab or nivolumab) as a standard of care in the discretion of the treating physician or Principal Investigator

• Must have at least 1 target lesion that is clinically accessible to RiMO-301 injection and amenable to receive RT regimens specified in this protocol

• The selected target lesions must be measurable on cross-sectional imaging and repeated measurements at the same location should be achievable

• Target tumor not in the previously irradiated field or in the field irradiated at least six months prior to RiMO-301 injection and with no complications from the prior radiation course

• RiMO-301 injection to multiple lesions (≤ 5 in total) in a single patient is allowed as long as the total tumor volume does not exceed 250 cm3

• Patient must have recovered from acute toxic effects (≤ grade 1 CTCAEv5) of previous cancer treatments prior to enrollment

• Have adequate bone marrow reserve and adequate liver function

• Have a life expectancy of at least 12 weeks

• ECOG score of 0-2

• Age 18 years or older

Exclusion Criteria:

• Have signs or symptoms of end organ failure, major chronic illnesses other than cancer, or any severe concomitant conditions
• Symptomatic central nervous system metastases and/or carcinomatous meningitis
• Active autoimmune disease that has required systemic treatment in the past 2 years
• Ongoing clinically significant infection at or near the incident lesion
• Major surgery over the target area (excluding placement of vascular access) ≤21 days from beginning of the study drug or minor surgical procedures ≤7 days. No waiting is required following implantable port, enteral feeding tube and catheter placement
• Has received any approved or investigational anti-neoplastic agent or immunotherapy other than PD-1 inhibitors (pembrolizumab or nivolumab) within 4 weeks prior to RiMO-301 injection
• Patients with lesions which have significant blood vessel involvement (such as carotid artery encasement) or other major structures