An antibody therapeutic, magrolimab, being tested for myelodysplastic syndrome (MDS), a group of cancers in which the bone marrow does not produce enough healthy blood cells , was granted breakthrough therapy designation with the Food and Drug Administration (FDA).
Breakthrough therapy designations from the FDA are intended to help expedite the development of new treatments. They require preliminary clinical evidence that demonstrates that the treatment may have substantial improvement in comparison to therapy options currently available. CIRM funded a Phase 1b trial in MDS and acute myeloid leukemia (AML), another type of blood cancer, that provided the data on which the breakthrough therapy designation is based.
Cancer cells express a signal known as CD47, which sends a “don’t eat me” message to macrophages, white blood cells that are part of the immune system designed to “eat” and destroy unhealthy cells. Magrolimab works by blocking the signal, enabling the body’s own immune system to detect and destroy the cancer cells.
Magrolimab was initially developed by a team led by Irv Weissman, M.D. at Stanford University with the support of CIRM awards. This led to the formation of Forty Seven, Inc., which was subsequently acquired by Gilead Sciences in April 2020 for $4.9 billion (learn more about other highlighted partnership events on CIRM’s Industry Alliance Program website by clicking here).
In CIRM’s 2019-2020 18-Month Report, Mark Chao, M.D., Ph.D., who co-founded Forty Seven, Inc. and currently serves as the VP of oncology clinical research at Gilead Sciences, credits CIRM with helping progress this treatment.
“CIRM’s support has been instrumental to our ability to rapidly progress Forty Seven’s CD47 antibody targeting approach.”
Magrolimab is currently being studied as a combination therapy with azacitidine, a chemotherapy drug, in a Phase 3 clinical trial in previously untreated higher risk MDS. This is one of the last steps before seeking FDA approval for widespread commercial use.
In a press release, Merdad Parsey, M.D., Ph.D., Chief Medical Officer at Gilead Sciences discusses the significance of the designation from the FDA and the importance of the treatment.
“The Breakthrough Therapy designation recognizes the potential for magrolimab to help address a significant unmet medical need for people with MDS and underscores the transformative potential of Gilead’s immuno-oncology therapies in development.”
With more than 17,000 members from nearly 100 countries, the American Society of Hematology (ASH) is an organization composed of clinicians and scientists around the world working to conquer various blood diseases. Currently, they are having their 61st Annual ASH Meeting to highlight some of the exciting work going on in the field. Four of our CIRM funded trials have released promising results at this conference and we wanted to take the opportunity to highlight them below.
Sangamo Therapeutics is conducting a CIRM-funded clinical trial for beta-thalassemia, a severe form of anemia caused by mutations in the hemoglobin gene. The therapy Sangamo is testing takes a patient’s own blood stem cells and, using a gene-editing technology called zinc finger nuclease (ZFN), provides a functional copy of the hemoglobin gene. These modified cells are then given back to the patient. The company announced preliminary results from their first three patients treated. in the clinical trials at the ASH 2019 Conference as well.
Some of the highlights are the following:
The first three patients experienced prompt hematopoietic reconstitution, meaning that their supply of blood stem cells was restored.
The first three patients experienced no clonal hematopoiesis, meaning that the blood stem cells did not create cells with mutations in the DNA
Additional study results are expected in late 2020 once enrollment is complete and all six patients have longer follow-up
You can read more detailed results regarding the first three patients in the press release.
Forty Seven, Inc.
In another CIRM funded trial, Forty Seven, Inc. is testing a treatment for myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). The treatment involves an antibody called magrolimab in combination with the chemotherapy drug azacitidine. Cancer cells express a signal that send a “don’t eat me” message to white blood cells that are part of the immune system designed to “eat” and destroy unhealthy cells. Magrolimab works by blocking the signal, enabling the body’s own immune system to detect these evasive cancer cells. The goal is to use both magrolimab and azacitidine to make the cancer stem cells vulnerable to being attacked and destroyed by the immune system.
Of the 46 patients evaluated, 24 patients had untreated higher-risk MDS and 22 patients had untreated AML. None of the patients were eligible for treatment with chemotherapy.
In higher-risk MDS, the overall response rate (ORR), which is the proportion of patients in a trial whose tumor is destroyed or significantly reduced by a treatment, was 92%.
Within this group of patients with an ORR, the following was observed:
12 patients (50%) achieved a complete response (CR), meaning that they experienced a disappearance of all signs of cancer in response to treatment.
Two patients (8%) achieved hematologic (blood) improvement.
Additionally, two patients (8%) achieved stable disease, meaning the cancer is neither increasing nor decreasing in extent or severity.
In untreated AML, the ORR was 64% and the following was observed within this group patients with an ORR:
Nine patients (41%) achieved a CR
Three patients (14%) achieved a CR with an incomplete blood count recovery (CRi)
One patient (5%) achieved a morphologic leukemia-free state (MLFS), which is defined as the disappearance of all cells with morphologic characteristics of leukemia, accompanied by bone marrow recovery, in response to treatment.
Seven patients (32%) achieved stable disease (SD)
The median time to response among MDS and AML patients treated with the combination was 1.9 months.
More details regarding these results are available via the news release.
Onceternal Therapeutics, which is conducting a CIRM-funded trial for a treatment for lymphoma and leukemia, presented results at the 2019 ASH Meeting. The treatment involves an antibody called cirmtuzumab (named after yours truly) being used with a cancer fighting drug called ibrutinib. The antibody recognizes and attaches to a protein on the surface of cancer stem cells. This attachment disables the protein, which slows the growth of the leukemia and makes it more vulnerable to anti-cancer drugs.
Some of the results presented are summarized as follows:
Twenty-nine of the 34 patients achieved a response, for an overall best objective response rate of 85%.
One patient achieved a complete response (CR) and remained in remission six months after completion of the trial and discontinuation of all anti-CLL therapy. In addition, three patients met radiographic and hematologic response criteria for Clinical CR.
Five patients had stable disease.
The total clinical benefit rate was 100%.
None of the patients died or saw their disease progress.
Patients achieved responses rapidly, with 68% of patients achieving a clinical response by three months on the combination therapy.
The rise in leukemic cell counts that is typically seen in the first six months with ibrutinib by itself was blunted with the addition of cirmtuzumab, and leukemic cell counts returned toward baseline and normal levels rapidly.
Last, but not least, Rocket Pharmaceuticals presented results at the 2019 ASH Conference related to a CIRM-funded trial for Leukocyte Adhesion Deficiency-I (LAD-I), a rare pediatric disease caused by a mutation in a specific gene that affects the body’s ability to combat infections. As a result, there is low expression of neutrophil (CD18). The company is testing a treatment that uses a patient’s own blood stem cells and inserts a functional version of the gene. These modified stem cells are then reintroduced back into the patient. The goal is to establish functional immune cells, enabling the body to combat infections.
Here are some of the highlights from the presentation:
Initial results from the first pediatric patient treated demonstrate early evidence of safety and potential effectiveness.
The patient exhibited early signs of engraftment
The patient also displayed visible improvement of multiple disease-related skin lesions after receiving therapy
No safety issues related to administration have been identified
More detailed results on this trial are available via the news release.
Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are both types of blood cancers that can be difficult to treat. CIRM is fundingForty Seven, Inc. to conduct a clinical trial to treat patients with these blood cancers with an antibody called 5F9. CIRM has also given multiple awards prior to the clinical trial to help in developing the antibody.
Cancer cells express a signal known as CD47, which sends a “don’t eat me” message to macrophages, which are white blood cells that are part of the immune system designed to “eat” and destroy unhealthy cells. The antibody works by blocking the signal, enabling the body’s own immune system to detect and destroy the cancer cells.
In a press release, Forty Seven, Inc. announced early clinical results from their CIRM funded trial using the antibody to treat patients with AML and MDS. Some patients received just the antibody while others received the antibody in combination with azacitidine, a chemotherapy drug used to treat these cancers.
Here is a synopsis of the trial:
35 patients treated in a Phase 1 clinical trial have been evaluated for a response assessment to-date.
10 of these have MDS or AML and only received the 5F9 antibody.
11 of these have higher-risk MDS and received the 5F9 antibody along with the chemotherapy drug azacitidine.
14 of these have untreated AML and received the 5F9 antibody along with the chemotherapy drug azacitidine.
For the 11 patients with higher-risk MDS treated with the antibody and chemotherapy, they found that:
All 11 patients achieved an objective response rate (ORR),meaning that there was a reduction in tumor burden of a predefined amount.
Six of these patients achieved a complete response (CR), indicatinga disappearance of all signs of cancer in response to treatment.
For the 14 patients with untreated AML treated with the antibody and chemotherapy, they found that:
Nine of these patients achieved an ORR.
Five of theseninepatients achieved a CR.
Two of these nine patientsachieved a morphologic leukemia-free state (MLFS), indicating the disappearance of all cells with formal and structural characteristics of leukemia, accompanied by bone marrow recovery, in response to treatment.
The remaining five patients achieved stable disease (SD), meaning that the tumor is neither growing nor shrinking.
The results also showed that:
There was no evidence of increased toxicities when the antibody was used alongside the chemotherapy drugs, demonstrating tolerance and safety of the treatment.
No responding MDS or AML patient has relapsed or progressed on the antibody in combination with chemotherapy, with a median follow-up of 3.8 months.
The median time to response was rapid at 1.9 months.
Several patients have experienced deepening responses over time resulting in complete remissions.
Based on the favorable results observed in this clinical trial to-date, expansion cohorts have been initiated, meaning that additional patients will be enrolled in a phase I trial. This will include patients with both higher-risk MDS and untreated AML as well as using the antibody in combination with chemotherapy.
In the press release, Dr. David Sallman, an investigator in the clinical trial, is quoted as saying,
“These new data for 5F9 show encouraging clinical activity in a broad population of patients with MDS and AML, who may be unfit for existing therapeutic options or at higher-risk for developing rapidly-advancing disease. Despite an evolving treatment landscape, physicians continue to seek new therapies for MDS and AML that can be used safely in combination with standard-of-care to help patients more rapidly achieve durable responses. To that end, I am excited to see meaningful clinical activity in a majority of patients treated with 5F9 in combination with azacitidine, with a median time to response of under two months and no relapses or progressions among responding patients.”
A variety of diseases can be traced to a simple root cause: problems in the bone marrow. The bone marrow contains specialized stem cells known as hematopoietic stem cells (HSCs) that give rise to different types of blood cells. As mentioned in a previous blog about Sickle Cell Disease (SCD), one problem that can occur is the production of “sickle like” red blood cells. In blood cancers like leukemia, there is an uncontrollable production of abnormal white blood cells. Another condition, known as myelodysplastic syndromes (MDS), are a group of cancers in which immature blood cells in the bone marrow do not mature and therefore do not become healthy blood cells.
For diseases that originate in the bone marrow, one treatment involves introducing healthy HSCs from a donor or gene therapy. However, before this type of treatment can take place, all of the problematic HSCs must be eliminated from the patient’s body. This process, known as pre-treatment, involves a combination of chemotherapy and radiation, which can be extremely toxic and life threatening. There are some patients whose condition has progressed to the point where their bodies are not strong enough to withstand pre-treatment. Additionally, there are long-term side effects that chemotherapy and radiation can have on infant children that are discussed in a previous blog about pediatric brain cancer.
Could there be a targeted, non-toxic approach to eliminating unwanted HSCs that can be used in combination with stem cell therapies? Researchers at Stanford say yes and have very promising results to back up their claim.
Dr. Judith Shizuru and her team at Stanford University have developed an antibody that can eliminate problematic blood forming stem cells safely and efficiently. The antibody is able to identify a protein on HSCs and bind to it. Once it is bound, the protein is unable to function, effectively removing the problematic blood forming stem cells.
Dr. Shizuru is the senior author of a study published online on February 11th, 2019 in Blood that was conducted in mice and focused on MDS. The results were very promising, demonstrating that the antibody successfully depleted human MDS cells and aided transplantation of normal human HSCs in the MDS mouse model.
This proof of concept holds promise for MDS as well as other disease conditions. In a public release from Stanford Medicine, Dr. Shizuru is quoted as saying, “A treatment that specifically targets only blood-forming stem cells would allow us to potentially cure people with diseases as varied as sickle cell disease, thalassemia, autoimmune disorders and other blood disorders…We are very hopeful that this body of research is going to have a positive impact on patients by allowing better depletion of diseased cells and engraftment of healthy cells.”
The research mentioned was partially funded by us at CIRM. Additionally, we recently awarded a $3.7 million dollar grant to use the same antibody in a human clinical trial for the so-called “bubble baby disease”, which is also known as severe combined immunodeficiency (SCID). You can read more about that award on a previous blog post linked here.