Examples of media coverage:
- FDA Gives HIV ‘Functional Cure’ Go-Ahead For Human Trials: Functional HIV Cure Step Closer To Reality With FDA Approval Of Clinical Human Trials – Medical Daily, March 10, 2015
- Study of potential HIV ‘cure’ wins FDA nod – San Francisco Business Times, March 3, 201
- Press Release: CIRM-funded Clinical Trial Aimed at Blocking HIV/AIDS in People Gets the Go Ahead – California Institute for Regenerative Medicine, March 3, 2015
These stories, which have been widely shared on social media (particularly the Medical Daily article), were prompted by a news release issued by the California Institute for Regenerative Medicine (CIRM). CIRM is supporting a team at the City of Hope in Los Angeles that plans to genetically modify stem cells to render them resistant to HIV, and test whether administration of these stem cells to HIV-positive individuals has a therapeutic effect.
The press release announced that the US Food and Drug Administration (FDA) has given approval for the conduct of a clinical trial in HIV-positive individuals experiencing a poor response to antiretroviral therapy (ART).
The trial will extract stem cells from the study participants, modify them with an approach developed by Sangamo BioSciences that aims to prevent expression of the CCR5 co-receptor that most HIV strains use to infect cells, then reinfuse the stem cells in hopes that they generate HIV-resistant immune cells (particularly CD4 T cells, HIV’s main target). Stem cells are responsible for generating all the different types of immune cells in the body, including CD4 T cells.
Sangamo’s approach has been used in several other clinical trials to modify CD4 T cells that are extracted from study participants and reinfused. The results have shown overall increases in CD4 T cells numbers, and a few participants have shown evidence of some degree of HIV viral load control after an ART interruption, but there have been no cases of a “functional cure” of HIV infection. The term “functional cure” is generally used to refer to a state in which HIV is not eradicated, but completely controlled without ongoing treatment, in a way that prevents the virus from causing any illness.
The problem with the Medical Daily and San Francisco Business Times headlines is that there is no evidence that the plan to deliver gene-modified stem cells will lead to a “cure” or a “functional cure” of HIV. The whole purpose of clinical trials is to assess the effects of an intervention, whereas the headlines mistakenly pre-judge what the effect of the intervention will be.
Previous trials involving transplantation of stem cells that were gene-modified to be resistant to HIV have found that the numbers of HIV-resistant CD4 T cells generated were very low. The new CIRM trial is an encouraging first step toward assessing whether stem cells modified with the Sangamo approach will perform better, but it is unfortunately extremely premature and misleading to describe the approach as a “functional cure” or potential “cure.”