Redefining a cure: What a stem cell therapy for HIV reminds us about clinical translation

Author: Holly Wobma, 08/22/12

With over 34 million people living with HIV, of which only the fortunate have continual access to life-saving anti-retroviral drugs, it comes as no surprise that the recent media announcement of a potential “cure” for HIV went rapidly…well…viral.

The excitement spurred from the XIX International AIDS Conference held in Washington DC (July 22-27, 2012) during which Dr. Daniel Kuritzkes, an infectious disease specialist at Harvard, revealed that two of his HIV infected patients now have undetectable virus levels several years after allogeneic bone marrow transplantation.

Of course, this isn’t the first time bone marrow transplantation has been used to reverse a person’s HIV status. Timothy Brown, a.k.a the “Berlin Patient”, is famous for being cured of his HIV after receiving a bone marrow transplant in 2007. His transplant was unique, however, in that it came from a person with a rare mutation (CCR5 receptor) that made cells intrinsically resistant to HIV infection. Clinicians were quick to point out that the rarity of this mutation made such a therapy unfeasible for large populations.

Enter Dr. Kuritzkes’s current study, in which he was able to achieve undetectable HIV levels in his patients using more widely available, normal bone marrow (i.e. lacking the CCR5 mutation), by keeping them on anti-retroviral drugs (ARVs). His hypothesis is that the ARVs protect the donor cells from infection by HIV, while the graft helps to kill off infected host cells.  Since his patients have yet to be taken off their ARVs, it is still unknown if their HIV negative status will be permanent.

But even if it is permanent, would this method truly be a cure?

Yes, but also no – in the sense that it is unlikely to become widespread. Bone marrow transplants, in general, are far too expensive and risky for large-scale implementation. Tim Brown and Dr. Kuritzkes’s patients received their transplants because they had co-morbidities of leukemias/lymphomas for which the risk-benefit ratio of this procedure is much more favorable.

While this seems a bit anti-climactic, it’s still an exciting and important discovery, and it strikes me as a poignant case study in the translation of stem cell therapies.

I mean, here we have a stem cell treatment – a potential cure for HIV – and yet, it is unlikely to be implemented in standard practice due to its potential morbidity and high cost. What a humbling reminder to us stem cell scientists that just because a treatment or cure “works” does not mean it is a feasible clinical solution at the population level!

From my experience, I would have to agree with one of our recent posts that sometimes researchers and students can become so enamored with the creativity and challenge that stem cell science and tissue engineering permit, that questions of translatability linger, neglected and unbeloved, in the periphery. This “scientific tunnel vision” is a pathology that many of us suffer from, at least at some point in our academic careers.

Given its overwhelming global presence, it is obvious that a cure for HIV, in the most tangible sense, must not only work but also be scalable, affordable, and accessible. However, these conditions also apply for treatments of spinal cord injuries, cardiovascular disease, diabetes – basically every ailment for which stem cell scientists are racing to find a cure.

While there is undoubtedly merit in basic science studies not yet at the stage of clinical translation, I think it is important for students, at all stages, to learn to keep these “bigger picture” questions in mind (CCRM and SCN are excellent forums for such discussions). Otherwise, the future of our collective research efforts will be something like a game of Scrabble, where multiple solutions exist to a problem, and yet nothing will manage to get off the table.

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Holly Wobma

Holly Wobma

MD/PhD student at Columbia University
Holly is an MD-PhD student at Columbia University in New York. She recently (2011) completed a Bachelor of Health Sciences Honours Degree from the University of Calgary, where she pursued research related to nanotechnology and regenerative medicine. In addition to research, she enjoys participating in science outreach roles. Previously, she contributed to an award-winning Nanoscience animation produced by the Science Alberta Foundation (“Do You Know What Nano Means?”), and served on the board of directors for the Canadian Institute for Photonic Innovations Student Network. Holly's lab tweets @GVNlab.
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