According to studies, modified citrus pectin (MCP) is able to chelate heavy metals like lead from tissues in humans without chelating healthy minerals, and it also has anti-cancer effects and prevents metastasis of cancer in studies:
Modified citrus pectin anti-metastatic properties: one bullet, multiple targets
It inhibits galectin-3, an enzyme that almost all cancers use for growth and metastasis.
It boosts the immune system including anti-cancer killer cells in a dose dependent matter in vitro, and it is shown to reduce PSA in prostate cancer patients and prevent prostate cancer growth. It can also induce apoptosis. It has underwent multiple big clinical trials as a therapy for cancer. The product can be bought as a supplement online, there's a company led by a doctor that originally developed it. Other supplement brands also sell it. The original product was used in the big studies. New studies are still on-going and cancer patients use the product.