CIRM-funded clinical trial shows encouraging results for patients with chronic lymphocytic leukemia & mantle cell lymphoma

Illustration courtesy of Oncternal Therapeutics

I often joke that my job here at CIRM is to be the official translator for the stem cell agency. I have to translate complex science into everyday English that people without a science background – that includes me – can understand.

Think I’m joking? Try making sense of this.

See what I mean. If you are a scientist this is not only perfectly clear, it’s also quite exciting. But for the rest of us……..

Actually, it is really quite exciting news. It’s about a CIRM-funded clinical trial being run by Oncternal Therapeutics to treat people with chronic lymphocytic leukemia (CLL), a kind of cancer where our body makes too many white blood cells. The study is using a combination therapy of Cirmtuzumab (a monoclonal antibody named after us because we helped fund its development) and ibrutinib, a conventional therapy used to treat cancers like CLL.

Cirmtuzumab recognizes and then attaches itself to a protein on the surface of cancer stem cells that the cancer needs to survive and spread. This attachment disables the protein (called ROR1) which slows the growth of the leukemia and makes it more vulnerable to anti-cancer drugs like ibrutinib.

In this Phase 1/2 clinical trial 12 patients were given the combination therapy for 24 weeks or more, making them eligible to determine how effective, or ineffective, the therapy is:

  • 11 of the 12 patients had either a partial response – meaning a reduction in the amount of detectable cancer – or a complete response to the treatment – meaning no detectable cancer.
  • None of the patients saw their cancer spread or grow
  • Three of the patients completed a year of treatment and they all showed signs of a complete response including no enlarged lymph nodes and white blood cell counts in the normal range.  

The combination therapy is also being used to treat people with Mantle Cell Lymphoma (MCL), a rare but fast-growing form of blood cancer. The results from this group, while preliminary, are also encouraging. One patient, who had experienced a relapse following a bone marrow transplant, experienced a complete response after three months of cirmtuzumab and ibrutinib.  

The data on the clinical trial was presented at a poster session (that’s the poster at the top of this blog) at the annual meeting of the American Society of Clinical Oncology.

In a news release Dr. James Breitmeyer, the President & CEO of Oncternal, said the results are very encouraging:  

“These data presented today, taken together with an earlier Phase 1 study of cirmtuzumab as a monotherapy in relapsed/refractory CLL, give us increased confidence in the potential for cirmtuzumab as a treatment for patients with ROR1-expressing lymphoid malignancies, particularly in combination with ibrutinib as a potential treatment for patients with CLL and MCL. We believe that the data also help to validate the importance of ROR1 as a therapeutic target,”

A cancer therapy developed at a CIRM Alpha Stem Cell Clinic tests its legs against breast cancer

Breast cancer cells

Three-dimensional culture of human breast cancer cells, with DNA stained blue and a protein on the cell surface membrane stained green. Image courtesy The National Institutes of Health

A Phase 1 clinical trial co-sponsored by CIRM and Oncternal Therapeutics, has started treating patients at UC San Diego (UCSD). The goal of the trial is to test the safety and anti-tumor activity of the Oncternal-developed drug, cirmtuzumab, in treating breast cancer.

Breast cancer is the second most common cancer to occur in women, regardless of race or ethnicity. More than 260,000 new cases are expected to be diagnosed this year in the United States alone. Typically, breast cancer cases are treated by a combination of surgery to remove the tumor locally, followed by some kind of systemic treatment, like chemotherapy, which can eliminate cancer cells in other parts of the body. In certain cases, however, surgery might not be a feasible option. Cirmtuzumab may be a viable option for these patients.

The drug acts by binding to a protein called ROR1, which is highly abundant on the surface of cancer cells. By blocking the protein Cirmtuzumab is able to promote cell death, stopping the cancer from spreading around the body.

Because ROR1 is also found on the surface of healthy cells there were concerns using cirmtuzumab could lead to damage to healthy tissue. However, a previous study revealed that using this kind of approach, at least in a healthy non-human primate model did not lead to any adverse clinical symptoms. Therefore, this protein is a viable target for cancer treatment and is particularly promising because it is a marker of many different types of cancers including leukemia, lung cancer and breast cancer.

Phase 1 clinical trials generally enroll a small number of patients who have do not have other treatment options. The primary goals are to determine if this approach is safe, if it causes any serious side-effects, what is the best dosage of the drug and how the drug works in the body. This clinical trial will enroll up to 15 patients who will receive cirmtuzumab in combination with paclitaxel (Taxol), a vetted chemotherapy drug, for six months.

Earlier this year, a similar clinical trial at UCSD began to test the effectiveness a of cirmtuzumab-based combination therapy to treat patients with B-cell cancers such as chronic lymphocytic leukemia. This trial was also partially funded by CIRM.

In a press release, Dr. Barbara Parker, the co-lead on this study states:

“Our primary objective, of course, is to determine whether the drug combination is safe and tolerable and to measure its anti-tumor activity. If it proves safe and shows effectiveness against breast cancer, we can progress to subsequent trials to determine how best to use the drug combination.”