A Biospecimen Collection Study of Leukapheresis-Derived Circulating Tumor Cells, Immune Cells, and Progenitor Cells.

This study collects blood and other biological samples (biospecimens) from cancer patients and healthy volunteers to help researchers study circulating tumor cells, immune cells, and stem-like cells. The goal is to better understand cancer biology and improve future treatments. Some participants may undergo a procedure called leukapheresis, which filters specific cells from your blood — similar to dialysis. You may be eligible if (Cancer patients): - You are 18 years of age or older - You have been diagnosed with any type of solid tumor at any stage - You have an adequate performance status and life expectancy of at least 3 months - You test negative for HIV, Hepatitis B, and Hepatitis C You may be eligible if (Healthy volunteers): - You are 18 or older (children aged 5–17 with suspected COVID-19 may qualify for limited, minimally invasive collection only) - You are generally healthy, including people with stable autoimmune conditions or COVID-19 - You test negative for HIV, Hepatitis B, and Hepatitis C You may NOT be eligible if: - You have an active infection currently requiring treatment (except COVID-19 in acute phase for leukapheresis exclusion) - You have a confirmed positive PCR test for HIV, Hepatitis B, or Hepatitis C - You have a medical condition that the investigator believes would make participation unsafe Talk to your doctor to see if this trial is right for you.