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The Miami Monkey: A Sunny Alternative to the Berlin Patient

2019; Cell Press; Volume: 50; Issue: 3 Linguagem: Inglês

10.1016/j.immuni.2019.02.010

1097-4180

Rachel A. Liberatore, David D. Ho,

vaccines and immunoinformatics approaches

Curing HIV infection has been impossible, with the exception of the "Berlin Patient." Martinez-Navio et al., 2019Martinez-Navio J.M.M. Fuchs S.P. Pantry S. Lauer W. Duggan N. Keele B. Rakasz E. Gao G. Lifson J. Desrosiers R.C. Long-term virologic suppression following AAV delivery of anti-HIV monoclonal antibodies.Immunity. 2019; 50 (this issue): 567-575Scopus (61) Google Scholar in Miami herein present a rare monkey whose virus was controlled for >3 years after a single genetic intervention that led to persistent production of HIV-neutralizing antibodies in vivo. Curing HIV infection has been impossible, with the exception of the "Berlin Patient." Martinez-Navio et al., 2019Martinez-Navio J.M.M. Fuchs S.P. Pantry S. Lauer W. Duggan N. Keele B. Rakasz E. Gao G. Lifson J. Desrosiers R.C. Long-term virologic suppression following AAV delivery of anti-HIV monoclonal antibodies.Immunity. 2019; 50 (this issue): 567-575Scopus (61) Google Scholar in Miami herein present a rare monkey whose virus was controlled for >3 years after a single genetic intervention that led to persistent production of HIV-neutralizing antibodies in vivo. Combination antiretroviral therapy enables many HIV-infected patients to remain free of detectable virus and to live a normal life for years or decades. However, such treatment is not curative, as HIV inevitably rebounds when antiretroviral drugs are stopped. The main barrier to virus eradication is believed to be a latent reservoir residing principally in resting memory CD4 (cluster of differentiation 4) T cells (Siliciano and Siliciano, 2016Siliciano J.D. Siliciano R.F. Recent developments in the effort to cure HIV infection: going beyond N = 1.J. Clin. Invest. 2016; 126: 409-414Crossref PubMed Scopus (48) Google Scholar). The only case to be cured of HIV infection is the so-called "Berlin Patient," Timothy Ray Brown (Hütter et al., 2009Hütter G. Nowak D. Mossner M. Ganepola S. Müssig A. Allers K. Schneider T. Hofmann J. Kücherer C. Blau O. et al.Long-term control of HIV by CCR5 Delta32/Delta32 stem-cell transplantation.N. Engl. J. Med. 2009; 360: 692-698Crossref PubMed Scopus (1352) Google Scholar), who received a hematopoietic stem cell transplant from a donor homozygous for a deletion in CCR5 (C-C chemokine receptor type 5), the coreceptor used by the vast majority of circulating HIV strains and a molecule absolutely required by those strains for infection. The transplant was administered after total-body irradiation and combination chemotherapy as part of his treatment for a diagnosis of acute myeloid leukemia. Extensive virologic testing showed that these interventions, along with antiretroviral therapy, had eliminated all evidence of HIV infection. It should be noted that these extraordinary measures would not have been taken in the absence of a leukemia diagnosis. The events of this single case, though surely not a viable treatment protocol for the more than 36 million people currently infected with HIV around the world, provided the first demonstration that a cure was indeed possible, thus triggering a resurgence of studies aimed at finding more practical means of achieving the same objective. Today, much research is focused on strategies directed at reactivating the latent HIV as a means to eliminating those infected cells comprising the latent reservoir (Siliciano and Siliciano, 2016Siliciano J.D. Siliciano R.F. Recent developments in the effort to cure HIV infection: going beyond N = 1.J. Clin. Invest. 2016; 126: 409-414Crossref PubMed Scopus (48) Google Scholar). No cure effort has yet produced even a modicum of success, the Berlin Patient notwithstanding. Therefore, millions of infected patients worldwide are still treated with an ever-expanding arsenal of antiretroviral drugs, which presumably will need to be continued lifelong in the absence of a cure. The varied classes of antiretroviral drugs, from the earliest reverse transcriptase and protease inhibitors to newer, more potent integrase inhibitors, have recently been joined by monoclonal antibodies directed to HIV receptors (CD4 and CCR5) or envelope glycoproteins. Monoclonal antibody therapy in general has blossomed in the past several years and is now part of the standard of care for a number of cancers and inflammatory diseases. The HIV and AIDS research field has made remarkable progress in the past decade in identifying and developing an impressive library of monoclonal antibodies that are not only potent but also broad in neutralizing a large panel of HIV strains in vitro. These are collectively referred to as broadly neutralizing antibodies, or bNAbs (Sok and Burton, 2018Sok D. Burton D.R. Recent progress in broadly neutralizing antibodies to HIV.Nat. Immunol. 2018; 19: 1179-1188Crossref PubMed Scopus (208) Google Scholar). A handful of bNAbs have been safely tested in infected patients and shown to be effective in stopping HIV replication in vivo (Bar-On et al., 2018Bar-On Y. Gruell H. Schoofs T. Pai J.A. Nogueira L. Butler A.L. Millard K. Lehmann C. Suárez I. Oliveira T.Y. et al.Safety and antiviral activity of combination HIV-1 broadly neutralizing antibodies in viremic individuals.Nat. Med. 2018; 24: 1701-1707Crossref PubMed Scopus (149) Google Scholar). Production of any therapeutic protein, not only bNAbs, is very expensive. Additionally, their use for the treatment of disease often necessitates frequent, parenteral administration by health professionals. Searching for cheaper and simpler alternatives, a number of investigators have turned to nucleic acid-based therapies, delivering either mRNA or DNA encoding the therapeutic protein and using a patient's own body as a bioreactor. The delivery of mRNA, typically by intravenous infusion, results in rapid, high levels of protein production, but expression usually wanes in a matter of days to weeks. DNA can be delivered as naked plasmids to muscle tissue with electroporation, resulting in the production of functional, antiviral antibodies for months in animals (Andrews et al., 2017Andrews C.D. Luo Y. Sun M. Yu J. Goff A.J. Glass P.J. Padte N.N. Huang Y. Ho D.D. In vivo production of monoclonal antibodies by gene transfer via electroporation protects against lethal influenza and Ebola infections.Mol. Ther. Methods Clin. Dev. 2017; 7: 74-82Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar). Alternatively, DNA can be encapsulated in recombinant adeno-associated virus (rAAV) vectors, from which expression can persist for years following delivery to long-lived cells. The first proof-of-concept study for this technology, rAAV-mediated delivery of antibody-like immunoadhesin proteins with potent antiviral activity, demonstrated persistent expression and protection from infection in a simian immunodeficiency virus challenge model in monkeys (Johnson et al., 2009Johnson P.R. Schnepp B.C. Zhang J. Connell M.J. Greene S.M. Yuste E. Desrosiers R.C. Clark K.R. Vector-mediated gene transfer engenders long-lived neutralizing activity and protection against SIV infection in monkeys.Nat. Med. 2009; 15: 901-906Crossref PubMed Scopus (263) Google Scholar). Even in these earliest studies with rAAV, however, the observed host anti-drug antibody (ADA) response to the transgene product was noted as an important challenge to overcome (Johnson et al., 2009Johnson P.R. Schnepp B.C. Zhang J. Connell M.J. Greene S.M. Yuste E. Desrosiers R.C. Clark K.R. Vector-mediated gene transfer engenders long-lived neutralizing activity and protection against SIV infection in monkeys.Nat. Med. 2009; 15: 901-906Crossref PubMed Scopus (263) Google Scholar). This immunogenicity problem is not restricted to the delivery of non-native molecules such as immunoadhesins but has proven to be a major obstacle to the successful delivery of antibodies with normal architecture as well (Martinez-Navio et al., 2016Martinez-Navio J.M.M. Fuchs S.P. Pedreño-López S. Rakasz E.G. Gao G. Desrosiers R.C. Host anti-antibody responses following adeno-associated virus-mediated delivery of antibodies against HIV and SIV in rhesus monkeys.Mol. Ther. 2016; 24: 76-86Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar). Nevertheless, the potential benefit of sustained bNAb expression has pushed the field forward, and in the rare cases in which rAAV delivery has worked, as described here, the results can be spectacular. To test the potential for rAAV-mediated bNAb delivery as a form of antiretroviral therapy, Martinez-Navio et al., 2019Martinez-Navio J.M.M. Fuchs S.P. Pantry S. Lauer W. Duggan N. Keele B. Rakasz E. Gao G. Lifson J. Desrosiers R.C. Long-term virologic suppression following AAV delivery of anti-HIV monoclonal antibodies.Immunity. 2019; 50 (this issue): 567-575Scopus (61) Google Scholar infected 4 rhesus monkeys with a simian/human immunodeficiency virus (SHIV). Plasma viral loads peaked as expected in the first few weeks post-infection, then settled into a range of 300–74,000 viral RNA copies/mL in the chronic phase, during which the infection was allowed to persist for more than 80 weeks in the absence of any treatment. The animals were then administered rAAV vectors encoding three chimeric monoclonal antibodies, consisting of the variable regions of human bNAbs 10E8 (Sok and Burton, 2018Sok D. Burton D.R. Recent progress in broadly neutralizing antibodies to HIV.Nat. Immunol. 2018; 19: 1179-1188Crossref PubMed Scopus (208) Google Scholar), 3BNC117, and 10-1074 (Bar-On et al., 2018Bar-On Y. Gruell H. Schoofs T. Pai J.A. Nogueira L. Butler A.L. Millard K. Lehmann C. Suárez I. Oliveira T.Y. et al.Safety and antiviral activity of combination HIV-1 broadly neutralizing antibodies in viremic individuals.Nat. Med. 2018; 24: 1701-1707Crossref PubMed Scopus (149) Google Scholar) fused to rhesus IgG1 constant regions. Strikingly, in one of the animals, there was a sharp decline in plasma viremia from approximately 10,000 viral RNA copies/mL to below the limit of detection of 15 copies/mL within a few weeks of the rAAV administration (Figure 1). Further analysis revealed that only this animal had maintained robust expression of more than one of the bNAbs. Because of the known association between rAAV delivery and ADA responses, the authors characterized the ADA profile of each of the animals, and the data revealed a tight correlation between the appearance of ADAs specific for each bNAb and the subsequent reduction in serum levels of that antibody. Although 3 of the animals developed ADAs against all 3 delivered antibodies, one animal (rh2438), here referred to as the "Miami Monkey," only developed ADAs against 10E8 but retained high serum concentrations of both 3BNC117 and 10-1074 (Figure 1). Remarkably, these antibodies have persisted at significant levels, and the SHIV plasma viremia has remained undetectable for more than 3 years. The extent of viral suppression in the Miami Monkey is indeed impressive. Efforts to recover infectious virus from this animal (and thus distinguish viral suppression from a cure) yielded multiple negative results from highly sensitive viral outgrowth assays, each using >107 cells, as well as adoptive transfers of lymph node cells (either 3 × 107 or 3 × 108) to uninfected monkeys through 78 weeks post-rAAV administration (Figure 1). Eventually, however, infectious SHIV was recovered from 3 samples (4–6 × 107 cells per sample) taken between 84 and 93 weeks post-rAAV administration (Figure 1), although the results were suggestive of a very small reservoir of cells harboring intact, latent proviral genomes. Nonetheless, repeated recovery of infectious virus, in contrast to the case of the Berlin Patient, rules out the possibility of a cure. The persistence of high concentrations of two bNAbs also preclude this monkey from being classified as a true "functional cure," defined as the suppression of virus in the absence of antiretroviral therapy (Trono et al., 2010Trono D. Van Lint C. Rouzioux C. Verdin E. Barré-Sinoussi F. Chun T.-W.W. Chomont N. HIV persistence and the prospect of long-term drug-free remissions for HIV-infected individuals.Science. 2010; 329: 174-180Crossref PubMed Scopus (241) Google Scholar). However, the Miami Monkey raises the prospect of a very attractive alternative: continued viral suppression with sustained antiretroviral therapy from a single therapeutic intervention. In an attempt to reproduce this result, Martinez-Navio et al., 2019Martinez-Navio J.M.M. Fuchs S.P. Pantry S. Lauer W. Duggan N. Keele B. Rakasz E. Gao G. Lifson J. Desrosiers R.C. Long-term virologic suppression following AAV delivery of anti-HIV monoclonal antibodies.Immunity. 2019; 50 (this issue): 567-575Scopus (61) Google Scholar then initiated a similar, but larger, study with 12 monkeys. Despite the fact that some changes were made to the experimental protocol in an effort to reduce immunogenicity, all 12 monkeys developed ADA responses to either all or all but one of the expressed bNAbs, and none were able to recapitulate the sunny outcome observed in the Miami Monkey. In total, the glaring fact remains that 16 out of 16 monkeys given rAAV developed some degree of ADAs. The messages delivered by this report (Martinez-Navio et al., 2019Martinez-Navio J.M.M. Fuchs S.P. Pantry S. Lauer W. Duggan N. Keele B. Rakasz E. Gao G. Lifson J. Desrosiers R.C. Long-term virologic suppression following AAV delivery of anti-HIV monoclonal antibodies.Immunity. 2019; 50 (this issue): 567-575Scopus (61) Google Scholar) are mixed: a largely unsuccessful strategy with a single spectacular success. It is clear from these and previous studies that a main barrier to rAAV-delivered bNAbs is the induction of ADA responses. Several groups of scientists are now trying to develop ADA-mitigation strategies to overcome this daunting challenge. ADA responses are likely exacerbated by the non-species-matched portion of the encoded proteins. Indeed, many of the ADA responses in a similar monkey study were directed against the human-derived variable regions, rather than the rhesus-derived constant regions (Martinez-Navio et al., 2016Martinez-Navio J.M.M. Fuchs S.P. Pedreño-López S. Rakasz E.G. Gao G. Desrosiers R.C. Host anti-antibody responses following adeno-associated virus-mediated delivery of antibodies against HIV and SIV in rhesus monkeys.Mol. Ther. 2016; 24: 76-86Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar). However, non-species-matched protein sequences cannot account for all the immunogenicity associated with rAAV-mediated delivery, because nearly all human study subjects who were administered higher doses of rAAV encoding the fully human bNAb PG9 also developed ADA responses, despite serum levels of PG9 that were undetectable by immunoassay (Gelderblom et al., 2018Gelderblom, H.C., Lewis, D.J.M., Streatfeld, C., Hassanin, H., Hare, J., Welsh, S., Bendel, D., Sayeed, E., Ackland, J., Wrin, T., et al., 2018, HIVR4P, conference.Google Scholar). Perhaps the most important take-home message from the Miami Monkey is the promise for nucleic acid-based therapies in general and, in particular, gene-transfer methodologies that are less immunostimulatory than the viral vectors currently in use. Technological breakthroughs in this area could, someday, allow us to move from expensive protein biologics to "bio-blueprints," enabling personal production of protein therapeutics. R.A.L. is an employee of RenBio, Inc. D.D.H. is a co-founder of and equity holder in RenBio, Inc. D.D.H. is also a co-founder and shareholder of TaiMed Biologics, Inc. Adeno-Associated Virus Delivery of Anti-HIV Monoclonal Antibodies Can Drive Long-Term Virologic SuppressionMartinez-Navio et al.ImmunityMarch 5, 2019In BriefAlthough anti-retroviral drug therapy can suppress HIV viral replication, it is not a cure. Martinez-Navio et al. report the functional cure of the "Miami monkey," in which long-term SHIV suppression was achieved after a single administration of adeno-associated viruses (AAVs) encoding broadly neutralizing antibodies. They also report that host-generated anti-antibodies can hamper the applicability of this approach. Full-Text PDF Open Archive