Two New Cases of 'HIV Remission'
During the 2013 IAS Conference taking place in Kuala Lumpur (Malaysia) from June 30 to July 3, a team of researchers from Boston (USA) have reported the lack of HIV rebound or detection in 2 patients who received allogenic stem cell transplantation for lymphomas and then had an analytic antiretroviral treatment interruption.
These patients were previously reported in part last June in the Journal of Infectious Diseases (1).
Compared to the Berlin patient:
-they did not receive total body irradiation,
-they received a less aggressive chemotherapy,
-the donors were wild type for the CCR5 gene.
The stem cell transplants were performed 2 and 5 years ago. As no HIV RNA or DNA was detectable as reported in the JID article, the patients finally were proposed to have an analytic treatment interruption.
HIV RNA and DNA are measured every week and large amounts of blood taken every 3 months for coculture.
After 8 weeks for one patient and 15 weeks for the other, no rebound of viremia has been observed as well as no detectable virus or provirus in PBMC and gut biopsy (2).
The authors state that they cannot tell if these patients have been 'cured' or not, as other reservoirs than those analysed could lead to a delayed rebound of viremia. They stress that these patients remained on antiretroviral drugs during the transplant process, to protect new cells from infection. One possibility is that the graft-verus-host reaction might have played a role in depleting the residual patients cells which were infected by HIV.
As graft-verus-host disease can be fatal, these patients were intermittently on and off immunosuppressive drugs and steroids to control it. One of the immunosuppressive drugs, sirolimus, may also have played a role in depleting the HIV reservoirs.
The authors indicate that such a procedure is certainly not a way to cure HIV infection for most patients as it carries a 15-20 percent risk of death. However, it is definitely a way to better understand the mechanisms of HIV persistence during cART.
1-Henrich TJ, Hu Z, Li JZ, et al. Long-term reduction in peripheral blood HIV type 1 reservoirs following reduced-intensity conditioning allogenic stem cell transplantation. Journal Infect Dis 2013; 207 (11): 1694-702
2-Henrich T, Hanhauser E, Sirignano M, et al. In depth investigation of peripheral and gut HIV-1 reservoirs, HIV-specific cellular immunity, and host microchimerism following allogeneic hematopoetic stem cell transplantation. 7th IAS Conference on Pathogenesis, Treatment and Prevention, Kuala Lumpur, Malaysia, June 30 - July 3, 2013, abstract WELBA05
Key words: HIV cure, HIV eradication, HIV persistence, HIV reservoirs