Ridding weeds from your lawn can be a frustrating experience without a good weeding tool in hand. If you don’t rip out the whole weed, root and all, it’s likely to grow back in no time.

Cancer patients and their physicians experience a similar frustration but with deadly consequences. Many current cancer treatment “tools” effectively destroy most but not all of the cancer. Often, the cancer ultimately returns with a vengeance, spreading throughout the body leading to organ failure and death.

What if you could figure out a way to seek out and destroy those few cancer cells that slip through the grasp of conventional anti-cancer drugs and therapy?

Blood smear showing chronic lymphocytic leukemia (CLL). The purple-stained cells are the CLL cells.

Today, a team from the UCSD Moore Cancer Center in partnership with Celgene Corporation announced that they’ve launched a CIRM-funded clinical trial that will embark on answering this question for people living with chronic lymphocytic leukemia (CLL). CLL is the most common form of blood cancer in adults. In the US alone, over 15,000 people are newly diagnosed annually.

In recent years, scientists have observed that a fraction of cancer cells within the leukemia or solid tumors have stem cell-like properties that allow them to continually grow in number and metastasize—in other words, spread throughout the body. During the development of an embryo, this immortal-like property is critical for the growth of the adult organism. But in taking advantage of this trait, these so-called cancer stem cells have made it very difficult for doctors to find and pull out the entire cancer “weed”.

But the UCSD team, led by Dr. Thomas Kipps, has potentially found the leukemia stem cells’ Achilles heel: a protein called ROR1 that sits on the surface of the cells and is responsible for boosting cell growth. ROR1 is normally not found on adult cells and only exists in embryonic cells. So the team produced a protein, called an antibody, that recognizes and clings tightly to ROR1, blocking its ability to function and to promote the cancer cells’ growth. No uncontrolled cell growth, no cancer.

Kipps summarized this point in a UCSD press release:

“Because cancer stem cells may require ROR1 for their growth, survival and movement through the body, targeting ROR1 could be a way to eradicate the seeds of the cancer that are responsible for metastasis or relapse after other forms of treatment.”

This initial clinical trial is focused on making sure the ROR1 antibody is safe and well-tolerated in 33 to 78 CLL patients in whom the cancer has either returned after conventional treatment or the treatments were ineffective from the start.

If the therapy, which goes by the name cirmtuzumab, is eventually found to be effective, Dr. Kipps envisions that it could be used in concert with conventional cancer drugs to hit the cancers from several angles:

“I see cirmtuzumab as perhaps also synergizing with other forms of treatment to provide for more effective anti-cancer therapies. It’s the cocktail approach, similar to what’s been shown to be effective in treating patients with HIV. Multiple drugs attack multiple targets of the cancer, each eliminating subsets of malignant cells. When combined with anti-ROR1 therapy, we might also block the recurrence of cancer after treatment.”

This announcement follows on the heels of last week’s announcements of the start of two other CIRM-funded trials for type 1 diabetes and spinal cord injury. There’s still a long road to approved therapies but the entire CIRM community is excited by these developments which we hope will bring treatments for people living with incurable diseases.