NCT04152863

Who might be able to join this trial:

• You have been diagnosed with advanced or metastatic melanoma (skin cancer that has spread), confirmed by a lab test.
• Your melanoma is classified as Stage III or Stage IV.
• You have never been treated with certain immunotherapy drugs called anti-PD-L1 treatments, or with oncolytic virus therapies (treatments that use viruses to fight cancer) such as TVEC.
• You have at least one skin or under-skin tumor that can be injected and measured, AND at least one separate tumor elsewhere in the body that can be biopsied and measured.
• You are in good enough general health to carry out daily activities with little or no limitation (as measured by a standard medical scale called ECOG, score 0 or 1).
• Your heart, liver, kidneys, and other organs are working well enough to meet the study's requirements.
• If you are male, you agree to avoid donating sperm and to either abstain from sex with women or use approved contraception during the study and for at least 120 days after your last dose.
• If you are female, you are not pregnant or breastfeeding, and if you could become pregnant, you agree to use contraception during the study and for at least 120 days after your last dose.
• Your cancer can be measured using standard imaging methods.
• You are able to provide a fresh tissue sample (biopsy) from a tumor that has not previously been treated with radiation.
• If you are living with HIV, your HIV must be well controlled on medication, with a strong enough immune cell count (CD4 over 350), your virus levels must be undetectable and stable, your HIV medications must not have changed for at least 4 weeks, and your HIV medication regimen must only include specific approved drugs (confirm with trial site).

Who may not be able to join:

• You have received chemotherapy, radiation, biological cancer therapy, or an experimental treatment within the past 4 weeks, or you are still experiencing significant side effects from a previous cancer treatment.
• Your melanoma started in the eye (ocular melanoma).
• Scans show that your cancer has grown into major blood vessels.
• You have had significant coughing up of blood or tumor bleeding within the past 2 weeks.
• You have an active autoimmune disease (where the immune system attacks the body) that has needed ongoing medical treatment in the past 2 years — with the exception of vitiligo or childhood asthma/allergies that have fully resolved.
• You are HIV-positive and have a history of a cancer called Kaposi's sarcoma or a condition called Multicentric Castleman's Disease.
• You have a psychiatric condition or substance use problem that would make it difficult to follow the study requirements.
• You have had a bone marrow or stem cell transplant from another person within the last 5 years.
• You have not fully recovered from major surgery, or you have a significant active infection following surgery.
• You have had a serious heart condition — such as a heart attack, unstable chest pain, heart failure, or a serious irregular heartbeat — within the past 6 months.
• You have previously been treated with certain immunotherapy drugs, including anti-PD-1, anti-PD-L1, anti-PD-L2, CTLA-4 blockers, or similar agents (confirm with trial site for specific drug names).
• You have received a live vaccine within the past 30 days.
• You are currently taking part in another clinical trial or have used an experimental treatment or device within the past 4 weeks.
• You have been diagnosed with an immune deficiency condition, or you are taking steroid medications above normal replacement levels, or any other immune-suppressing medication within the past 7 days.
• You have another cancer that is currently active or has required treatment within the past 2 years.
• You have active cancer spread to the brain or the lining around the brain and spinal cord.
• You have a known allergy to pembrolizumab or gebasaxturev (the study drugs) or any of their ingredients.
• You have a history of lung inflammation (pneumonitis) that needed steroid treatment, or you currently have pneumonitis.
• You have an active infection that requires treatment with medication.
• You have a known history of Hepatitis B, or an active Hepatitis C infection.
• You have any other condition,