Study did not commence.

This open label, randomized study will evaluate safety and tolerability of sargramostim when combined with an ipilimumab-containing regimen received as part of standard of care therapy. The study will evaluate 2 sargramostim administration schedules. Patients will be randomized 1:1 to the sargramostim administration schedules and stratified based on planned dose of ipilimumab (1 mg/kg, 3 mg/kg).

Sargramostim will be administered for the first 12 weeks following the assigned treatment schedule or until disease progression, intolerable toxicity, consent withdrawal, pregnancy, or death, whichever comes first. Checkpoint inhibitor therapy will be administered in accordance with institutional standard of care guidelines, at the Investigator's discretion.

Patients will be followed up for to 24 weeks following end of sargramostim treatment for safety, efficacy, and survival.

Inclusion Criteria:

• Adult patients with solid tumors that will start an ipilimumab-containing therapy (with or without anti-PD-1, such as nivolumab) as part of standard of care in approved ipilimumab indication
• Recovery from any toxicities related to prior therapies
• Ability and willingness to self-administer or have a caregiver administer a SC injection of sargramostim
• Women of child-bearing potential willing to use birth control

Exclusion Criteria:

• Recent radiation therapy for cancer that has spread to bones or to the brain
• History of a severe reaction to prior immune checkpoint inhibitors
• Pleural or pericardial effusion, or history of recurrent pleural or pericardial effusion.
• Heart rhythm with symptoms within the last 12 months
• Known or suspected intolerance or hypersensitivity to sargramostim or any product component or diluent
• Use drugs that can suppress the immune system
• Women who are pregnant or breastfeeding
• Live virus vaccine within 28 days prior to study treatment and for 4 weeks after study treatment.
• Have other active cancers
• Participation in another clinical trial
• Any other medical condition or laboratory abnormality that would put patient at risk or confound interpretation of trial results