A Phase I, Open-Label Study To Assess The Safety, Feasibility and Engraftment of Zinc Finger Nucleases (ZFN) CCR5 Modified Autologous CD34+ Hematopoietic Stem/Progenitor Cells (SB-728MR-HSPC) with Escalating Doses of Busulfan In HIV-1 (R5) Infected Sub…

The HIV-1 virus enters cells by binding to a protein called CCR5 on the cell surface. A naturally occurring mutation in CCR5, CCR532, has been shown to provide protection from HIV-1 infection and AIDS. Media and scientific magazines have discussed widely the case of the “Berlin patient,” who was cured of his HIV-1 infection after receiving therapy for his leukemia with a blood stem cell transplant from a donor whose cells had both copies of CCR5 mutated. This strategy is unlikely to be successful for the AIDS patient in general since donors must be a near-perfect tissue match with the patient and also have the double CCR5 mutation, two rare events which almost never happen together. To mimic the effect of the CCR5 double mutation, this project creates blood stem cells that have a double mutation in the CCR5 gene and then test this gene therapy method in HIV-infected research participants. The participants’ own blood stem cells are treated in a process that can mutate the CCR5 gene, and then the stem cells are infused back into the individual. These cells carry the disrupted CCR5 gene. We administer a low dose of chemotherapy called busulfan to the recipient prior to the transplant to provide space for the new stem cells. We anticipate that, upon stem cell infusion, the gene-modified cells will provide a renewable, long-lasting source of HIV-1 resistant immune cells. This novel strategy gets around the need to find a stem cell donor who carries the CCR5 double mutation and, since the stem cells come from the patient, there will be an ideal “perfect match” with no chance for rejection in the patient. The applicant institution has worked with collaborating partners to start the study in July 2015. Three participating clinics screen and enroll the eligible participants. So far, we have enrolled the first research participant and have successfully mobilized and collected the blood stem cells and have manufactured the gene-modified blood stem cells. We are now in the process of testing of this investigational product. Screening of potential participants continues at the clinics currently open to recruitment. It is planned to add more clinics to the study in the current funding year. This is a partnership among City of Hope, Sangamo Biosciences Inc, and CIRM. With combined expertise in stem cells, gene therapy, transplantation, treatment of HIV-related disease, this Strategic Partnership has the knowledge, skill and resources to achieve all project goals.

Reporting Period:

OM#1

Reporting Period:

OM #2

This clinical project aims to create blood stem cells that have a disrupted CCR5 gene, which can no longer produce a protein used by the HIV-1 virus to enter the cells. The blood cells derived from these stem cells would then be protected from HIV infection. The goal is to test the safety and feasibility of this gene therapy method in HIV-infected research participants. The participants’ own blood stem cells are collected and then treated in a process that can attack the CCR5 gene, and then the stem cells are infused back into the individual. To assure that these cells find a place to grow in the bone marrow of the recipient, a low dose of chemotherapy called busulfan is given to the recipient prior to infusion of the CCR5-modified stem cells. It is anticipated that, upon stem cell infusion, the gene-modified cells will provide a renewable, long-lasting source of HIV-1 resistant immune cells. This novel strategy tries to achieve the results seen with the publicized case of the “Berlin patient.” This patient was cured of his HIV-1 infection after receiving therapy for his leukemia with a blood stem cell transplant from a donor who inherited disrupted CCR5 genes. The applicant institution has worked with collaborating partners to start the study in July 2015. Six participating clinics screen and enroll the eligible participants. The first 3 research participants have had the gene-modified blood stem cells manufactured and successfully treated with this product after low dose chemotherapy. With this, the first milestone for this project was achieved. With the infusion of the fourth research participant after higher dose chemotherapy, the second milestone has been achieved. The progress advances with continued enrollment of more patients into the study with the goal of achieving the next milestone, the treatment of the ninth participant. This is a partnership among City of Hope, Sangamo Therapeutics Inc, and CIRM. With combined expertise in stem cells, gene therapy, transplantation, treatment of HIV-related disease, this Strategic Partnership has the knowledge, skill and resources to achieve all project goals.

Reporting Period:

OM#4 – FINAL

For this Phase 1/pilot clinical trial in HIV funded by CIRM and Sangamo Therapeutics and sponsored by City of Hope, eight persons living with HIV (PLH) underwent a transplantation using their own stem cells modified by disruption of the CCR5 gene. The absence of the CRR5 gene has been shown to protect against HIV infection. The goal of the study was to determine if this approach was safe and feasible. In addition, the study attempted to determine if study participants who stopped the antiretroviral therapy would be protected from recurrence of HIV in their blood and whether the CCR5-disrupted blood cells would be protected from this HIV "rebound."

This was the first systematic trial of gene-editing of blood stem cells and used the method of zinc finger nucleases (ZFN) to edit the CCR5 gene followed by infusion of these cells after busulfan treatment. The study team has finalized the preliminary Clinical Study Report (CSR) with clinical trial data from the first 4 years of follow-up. These are the preliminary conclusions from the study:

Genome editing of CCR5 in blood stem cells from PLH is feasible using the methods of this study. The process was safe. Patients were given a low or a high dose of busulfan, and engraftment of the gene modified cells was improved at the higher busulfan dose. There was long-term expression of the disrupted CCR5 gene in peripheral blood and bone marrow. There is a low percentage of cells with CCR5 disruption, but as noted, this low level was maintained for the duration of the study. We were able to perform an analytical treatment interruption, aka, stopping antiretroviral medication, in 4 study participants until their HIV viral load returned. Expression of HIV during this period did not appear to select for CCR5 disrupted cells.

In conclusion, this novel method of CCR5 disruption was shown to be safe and feasible. Future improvements in this method will require more efficient gene editing tools, if HIV cure will be possible.

Grant Application Details

Application Title:

A Phase I, Open-Label Study to Assess the Safety, Feasibility and Engraftment of Zinc Finger Nucleases (ZFN) CCR5 Modified Autologous CD34+ Hematopoietic Stem/Progenitor Cells with Escalating Doses of Busulfan in HIV-1 (R5) Infected Subjects with Subop...

Public Abstract:

The HIV-1 virus enters cells by binding to a protein called CCR5 on the cell surface. A naturally occurring mutation in CCR5, CCR5d32, has been shown to provide protection from HIV-1 infection and AIDS. All individuals carry two copies of the CCR5 gene, and those with both copies of CCR5 mutated are highly resistant to infection with HIV-1. Those carrying one mutated copy can get infected by HIV-1, but have a delayed progression to AIDS. Media and scientific magazines have discussed widely the case of the “Berlin patient,” who was cured of his HIV-1 infection after receiving therapy for his leukemia with a blood stem cell transplant from a donor whose cells had both copies of CCR5 mutated. Other HIV-1 infected patients have not been treated in this way since donors must be a near-perfect tissue match with the patient and also have the double CCR5 mutation, two rare events which almost never happen together.

To mimic the effect of the CCR5 double mutation, we propose to create blood stem cells that have a double mutation in the CCR5 gene and then test this gene therapy method in patients. The patients’ own blood stem cells will be treated in a process that can mutate the CCR5 gene, and then the stem cells will be transplanted back into the individual. These cells will carry the disrupted CCR5 gene and provide a renewable, long-lasting source of HIV-1 resistant immune cells. This novel strategy gets around the need to find a stem cell donor who carries the CCR5 double mutation and, since the stem cells come from the patient, there will be an ideal “perfect match” with no chance for rejection in the patient.

Results from mice transplanted with blood stem cells treated in this way have shown that the modified cells are functional and produce CCR5 mutant (HIV-1 resistant) progeny cells. When infected with HIV-1, these mice have reduced viral loads, and, importantly, the CCR5-disrupted CD4 cells have strong survival advantage. In the proposed clinical trial, HIV-1 infected patients with low levels of CD4 cells and no detectable HIV-1 while on antiviral medications will have their own blood stem cells modified at the CCR5 gene. Modified cells will then be re-infused into the patient after treatment with a chemotherapy agent, busulfan, which makes room for the stem cells to “take hold” in the marrow and generate an immune system with CCR5-mutant, HIV-1 resistant cells.

The applicant institution has worked with collaborating partners to develop this treatment method (a project funded by CIRM). They successfully developed this gene modification method up to the clinical testing phase. With combined expertise in stem cells, gene therapy, transplantation, treatment of HIV-related disease, this Strategic Partnership has the knowledge and skill to achieve all project goals.

Statement of Benefit to California:

California has the second highest number of persons living with HIV-1/AIDS in the United States. By the end of 2008, there were 100,366 adults and adolescents reported to be living with HIV-1 or AIDS in California (Cf. Scheer S et al, The Open AIDS Journal, 2012, 6(Suppl 1):188). This incidence translates into a medical and fiscal burden larger than any other state, except New York. A study from 2011 reported that public funding accounted for approximately $1.92 billion in HIV-1/AIDS services in California in the fiscal year 2008, of which the majority (90.4%) supported treatment (Cf. Leibowitz AA et al, J Acquir Immune Defic Syndr 2011;58:e11). In the fiscal year 2007-08, the California AIDS Drug Assistance Program (ADAP) served 32,842 clients and filled over 953,000 prescriptions for these clients. The Governor's current spending plan (2013-14 Budget Act) called for $448.4M to support this program, with sources coming from federal and California state funds. With these huge costs and HIV-1/AIDS being a life-long infection that requires compliant daily treatment medication for a lifetime, the need for a cure that has the potential to reduce the duration of antiviral therapy is substantial. Most importantly, such a therapy would significantly impact the quality of life of persons with HIV-1/AIDS. If successful, a stem cell-based therapy, though expensive as a single treatment, would significantly reduce the cost burden on the state and federal treatment programs and save money over the lifetime of a patient. The estimated cost of lifelong cART therapy is estimated to be $420,000 -$755,000 USD, with 73% of the cost going to cART drugs (Cf. Sloan CE et al. AIDS 2012, 26, 45). Conversion to generic first line combination cART drugs is estimated to only reduce costs by ~ $42,000/patient (Cf. Walensky R.P et al. Ann Intern Med 2013, 158, 84). Furthermore, not all patients with HIV-1 infection fully respond to the therapy; in fact, about one fifth of patients have an inadequate immune response despite keeping the virus at undetectable levels. These patients are at increased risk of infection and chronic diseases, which also impact the health spending of California. There is no treatment for such patients and, if successful, the cellular therapy derived from genetically modified blood stem cells proposed here would have a major impact on patient management and outcome. Success of this therapy would establish the safety of a possible future cure for HIV-1/AIDS. Added benefits are: 1) this stem cell-based gene therapy for HIV-1/AIDS will have a positive impact on the overall field of stem cell research with application to other diseases; 2) this demonstrates the progression of new technology supported by CIRM to the clinic, and 3) the technology was derived from California-based industry and success should have a positive economic impact in the state.