Today, December 1st, is World AIDS Day. It’s a day to acknowledge the progress that is being made in HIV prevention and treatment around the world but also to renew our commitment to a future free of HIV. This year’s theme is Leadership. Commitment. Impact. At CIRM we are funding a number of projects focused on HIV/AIDS, so we asked Jeff Sheehy, the patient advocate for HIV/AIDS on the CIRM Board to offer his perspective on the fight against the virus.
At CIRM we talk about and hope for cures, but our actual mission is “accelerating stem cell treatments to patients with unmet medical needs.”
For those of us in the HIV/AIDS community, we are tremendously excited about finding a cure for HIV. We have the example of Timothy Brown, aka the “Berlin Patient”, the only person cured of HIV.
Multiple Shots on Goal
Different approaches to a cure are under investigation with multiple clinical trials. CIRM is funding three clinical trials using cell/gene therapy in attempts to genetically modify blood forming stem cells to resist infection with HIV. While we hope this leads to a cure, community activists have come together to urge a look at something short of a “home run.”
A subset of HIV patients go on treatment, control the virus in their blood to the point where it can’t be detected by common diagnostic tests, but never see their crucial immune fighting CD4 T cells return to normal levels after decimation by HIV.
For instance, I have been on antiretroviral therapy since 1997. My CD4 T cells had dropped precipitously, dangerous close to the level of 200. At that level, I would have had an AIDS diagnosis and would have been extremely vulnerable to a whole host of opportunistic infections. Fortunately, my virus was controlled within a few weeks and within a year, my CD T cells had returned to normal levels.
For the immunological non-responders I described above, that doesn’t happen. So while the virus is under control, their T cell counts remain low and they are very susceptible to opportunistic infections and are at much greater risk of dying.
Immunological non-responders (INRs) are usually patients who had AIDS when they were diagnosed, meaning they presented with very low CD4 T cell counts. Many are also older. We had hoped that with frequent testing, treatment upon diagnosis and robust healthcare systems, this population would be less of a factor. Yet in San Francisco with its very comprehensive and sophisticated testing and treatment protocols, 16% of newly diagnosed patients in 2015 had full blown AIDS.
Until we make greater progress in testing and treating people with HIV, we can expect to see immunological non-responders who will experience sub-optimal health outcomes and who will be more difficult to treat and keep alive.
Boosting the Immune System
A major cell/gene trial for HIV targeted this population. Their obvious unmet medical need and their greater morbidity/mortality balanced the risks of first in man gene therapy. Sangamo, a CIRM grantee, used zinc finger nucleases to snip out a receptor, CCR5, on the surface of CD4 T cells taken from INR patients. That receptor is a door that HIV uses to enter cells. Some people naturally lack the receptor and usually are unable to be infected with HIV. The Berlin Patient had his entire immune system replaced with cells from someone lacking CCR5.
Most of the patients in that first trial saw their CD4 T cells rise sharply. The amount of HIV circulating in their gut decreased. They experienced a high degree of modification and persistence in T stem cells, which replenish the T cell population. And most importantly, some who regularly experienced opportunistic infections such as my friend and study participant Matt Sharp who came down with pneumonia every winter, had several healthy seasons.
Unfortunately, the drive for a cure pushed development of the product in a different direction. This is in large part to regulatory challenges. A prior trial started in the late 90’s by Chiron tested a cytokine, IL 2, to see if administering it could increase T cells. It did, but proving that these new T cells did anything was illusive and development ceased. Another cytokine, IL 7, was moving down the development pathway when the company developing it, Cytheris, ceased business. The pivotal trial would have required enrolling 4,000 participants, a daunting and expensive prospect. This was due to the need to demonstrate clinical impact of the new cells in a diverse group of patients.
Given the unmet need, HIV activists have looked at the Sangamo trial, amongst others, and have initiated a dialogue with the FDA. Activists are exploring seeking orphan drug status since the population of INRs is relatively small.
Charting a New Course
They have also discussed trial designs looking at markers of immune activity and discussed potentially identifying a segment of INRs where clinical efficacy could be shown with far, far fewer participants.
Activists are calling for companies to join them in developing products for INRs. I’ve included the press release issued yesterday by community advocates below.
With the collaboration of the HIV activist community, this could be a unique opportunity for cell/gene companies to actually get a therapy through the FDA. On this World AIDS Day, let’s consider the value of a solid single that serves patients in need while work continues on the home run.
NEWS RELEASE: HIV Activists Seek to Accelerate Development of Immune Enhancing Therapies for Immunologic Non-Responders.
Dialogues with FDA, scientists and industry encourage consideration of orphan drug designations for therapies to help the immunologic non-responder population and exploration of novel endpoints to reduce the size of efficacy trials.
November 30, 2016 – A coalition of HIV/AIDS activists are calling for renewed attention to HIV-positive people termed immunologic non-responders (INRs), who experience sub-optimal immune system reconstitution despite years of viral load suppression by antiretroviral therapy. Studies have shown that INR patients remain at increased risk of illness and death compared to HIV-positive people who have better restoration of immune function on current drug therapies. Risk factors for becoming an INR include older age and a low CD4 count at the time of treatment initiation. To date, efforts to develop immune enhancing interventions for this population have proven challenging, despite some candidates from small companies showing signs of promise.
“We believe there is an urgent need to find ways to encourage and accelerate development of therapies to reduce the health risks faced by INR patients,” stated Nelson Vergel of the Program for Wellness Restoration (PoWeR), who initiated the activist coalition. “For example, Orphan Drug designations[i] could be granted to encourage faster-track approval of promising therapies. These interventions may eventually help not only INRs but also people with other immune deficiency conditions”.
Along with funding, a major challenge for approval of any potential therapy is proving its efficacy. While INRs face significantly increased risk of serious morbidities and mortality compared to HIV-positive individuals with more robust immune reconstitution, demonstrating a reduction in the incidence of these outcomes would likely require expensive and lengthy clinical trials involving thousands of individuals. Activists are therefore encouraging the US Food & Drug Administration (FDA), industry and researchers to evaluate potential surrogate markers of efficacy such as relative improvements in clinical problems that may be more frequent in INR patients, such as upper respiratory infections, gastrointestinal disease, and other health issues.
“Given the risks faced by INR patients, every effort should be made to assess whether less burdensome pathways toward approval are feasible, without compromising the regulatory requirement for compelling evidence of safety and efficacy”, said Richard Jefferys of the Treatment Action Group.
The coalition is advocating that scientists, biotech and pharmaceutical companies pursue therapeutic candidates for INRs. For example, while gene and anti-inflammatory therapies for HIV are being assessed in the context of cure research, there is also evidence that they may have potential to promote immune reconstitution and reduce markers associated with risk of morbidity and mortality in INR patients. Therapeutic research should also be accompanied by robust study of the etiology and mechanisms of sub-optimal immune responses.
“While there is, appropriately, a major research focus on curing HIV, we must be alert to evidence that candidate therapies could have benefits for INR patients, and be willing to study them in this context”, argued Matt Sharp, a coalition member and INR who experienced enhanced immune reconstitution and improved health and quality of life after receiving an experimental gene therapy.
The coalition has held an initial conference call with FDA to discuss the issue. Minutes are available online.
The coalition is now aiming to convene a broader dialogue with various drug companies on the development of therapies for INR patients. Stakeholders who are interested in becoming involved are encouraged to contact coalition representatives.
[i] The Orphan Drug Act incentivizes the development of treatments for rare conditions. For more information, see: http://www.fda.gov/ForIndustry/DevelopingProductsforRareDiseasesConditions/ucm2005525.htm
For more information:
Michael Palm Basic Science, Vaccines & Cure Project Director
Treatment Action Group firstname.lastname@example.org
Nelson Vergel, Program for Wellness Restoration email@example.com