This research study is testing a new treatment called CF33-CD19 for adults with advanced (very serious) or metastatic (spread to other parts of the body) solid tumors. CF33-CD19 is a special virus that may help fight cancer cells. It is given alone or with another medicine named blinatumomab and sometimes with hydroxyurea. The study will help doctors understand if this treatment is safe, how the body responds, and if it helps fight cancer.

• Duration: Treatment involves cycles of 21 or 28 days, depending on the combination.
• Visits: Regular visits for treatment and check-ups are required.
• Eligibility: Must be 18+, with specific health conditions, and not have had similar treatments before.

Participants need to be willing to follow the study schedule and undergo tests. This study might help in developing new cancer treatments, but it's important to consider the commitment and potential risks before joining.