Simplified steps to heterologous prime-boost HIV vaccine development? Nelson L. Michael J Clin Invest. 2019;129(11):4572-4573. https://doi.org/10.1172/JCI132440. Commentary The RV 144 HIV vaccine efficacy study showed a reduction in HIV-1 infection risk in Thai volunteers who received two priming vaccinations of vCP1521 ALVAC (attenuated recombinant canarypox virus expressing HIV group–specific antigen, polymerase, and envelope genes) followed by two additional ALVAC vaccinations and coadministration of purified bivalent gp120 proteins (AIDSVAX B/E). In this issue of the JCI, Rouphael et al. build on these results by substituting a DNA plasmid cocktail expressing HIV-1 subtype C group–specific antigen, polymerase, and envelope antigen genes (DNA-HIV-PT123) for ALVAC in a phase 1b safety and immunogenicity study. The results indicate that the vaccine regimen is safe, elicits promising cross-subtype humoral and cellular responses, and opens up potentially simplified approaches to HIV-1 vaccine development. Find the latest version: https://jci.me/132440/pdf COMMENTARY The Journal of Clinical Investigation Simplified steps to heterologous prime-boost HIV vaccine development? Nelson L. Michael Center for Infectious Diseases Research, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA. replaced in the current study by a cocktail of three DNA plasmids, DNA-HIV-PT123, The RV 144 HIV vaccine efficacy study showed a reduction in HIV-1 which consists of equal amounts of plas- infection risk in Thai volunteers who received two priming vaccinations of mids expressing HIV-1 subtype C sequenc- vCP1521 ALVAC (attenuated recombinant canarypox virus expressing HIV es: HIV-1 gag, HIV-1 gp140, and group–specific antigen, polymerase, and envelope genes) followed by two ZM96 ZM96 HIV-1CN54 pol-nef, delivered at a total dose additional ALVAC vaccinations and coadministration of purified bivalent of 4 mg administered intramuscularly via gp120 proteins (AIDSVAX B/E). In this issue of the JCI, Rouphael et al. build needle and syringe. on these results by substituting a DNA plasmid cocktail expressing HIV-1 Subjects in the first study arm (T1) subtype C group–specific antigen, polymerase, and envelope antigen genes were primed with AIDSVAX B/E fol- (DNA-HIV-PT123) for ALVAC in a phase 1b safety and immunogenicity study. lowed by DNA boost without coadminis- The results indicate that the vaccine regimen is safe, elicits promising cross- tration, and subjects in the second study subtype humoral and cellular responses, and opens up potentially simplified arm (T2) received the same vaccines, but approaches to HIV-1 vaccine development. in reversed order (2). Thus, T2 includes the use of the AIDSVAX B/E boost at the month 3 and month 6 vaccination visits after priming with a DNA-based vaccine, as was done in RV 144. In the third study Attempting to improve a regimen in the benchmark RV 144 study arm (T3), subjects were given DNA-HIV- vaccination strategy with included ALVAC vCP1521, which expresses PT123as the prime at the first and second demonstrated efficacy HIV-1LAI gag/pol sequences (subtype B) along vaccination visits followed by coadminis- The Thai HIV vaccine efficacy trial RV 144 with HIV-192TH023 gp120 env (subtype circu- tration of DNA-HIV-PT123 and AIDSVAX evaluated an approach that combined an lating recombinant form 1_AE [CRF_01AE]) B/E at the third and fourth vaccination vis- ALVAC vCP1521 (a canarypox-vectored HIV with a partial extension into the transmem- its. The T3 arm was the most homologous expressing group-specific antigen, poly- brane domain of gp41, and was given four to the RV 144 regimen, which used vCP121 merase, and envelope antigen–encoding times (at baseline and then at months 1, 3, ALVAC vaccinations at all four vaccination genes [gag/pol/env]) prime with an AIDS- and 6). AIDSVAX B/E, which is composed visits and coadministration of AIDSVAX VAX B/E (bivalent gp120 monomeric Env of purified gp120 Env proteins from HIV-1MN B/E (albeit in different anatomical loca- protein) heterologous boost (1). To date, this (subtype B) and HIV-1A244 (subtype CRF01_ tions) at the third and fourth vaccination prime-boost regimen is the only strategy AE) variants adsorbed to alum, was given at visits. The fourth study arm (T4) included that has demonstrated efficacy in prevent- the same time as ALVAC vCP1521 in sepa- coadministration of DNA-HIV-PT123 and ing HIV acquisition in humans; however, the rate injections in the ipsilateral deltoid mus- AIDSVAX B/E at all four vaccination visits. overall protection was relatively modest (1). cle of volunteers at months 3 and 6. Immunogenicity was broadly assessed by In this issue, Rouphael et al. extend upon the The study design of Rouphael and Rouphael et al., and their analysis includ- RV 144 trial and evaluated the effect of sub- colleagues included four independent ed HIV-1 Env antibody binding stratified stituting a DNA vaccine for ALVAC vCP1521 arms with vaccinations given at 0, 1, 3, by IgG subclass and V1V2 scaffold bind- in four study arms of a phase 1, randomized, and 6 months (2). AIDSVAX B/E was ing, neutralizing antibody (nAb) assays, double-blinded, placebo-controlled safe- administered in the same dose and route and antibody-dependent cell-mediated ty and immunogenicity study performed as was used in RV 144; however, the cytotoxicity (ADCC). Cellular immuni- at multiple study centers (2). The vaccine ALVAC vCP1521 boost used in RV 144 was ty was assessed by intracellular cytokine staining and the computational biolo- gy–based T cell polyfunctional assay, the Related Article: p. 4769 combinatorial polyfunctionality analysis of single cells (COMPASS) assay. Notably, Conflict of interest: The author has declared that no conflict of interest exists. measures of cellular immunity were found Disclaimer: Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its to correlate with risk of HIV infection in presentation and/or publication. The opinions or assertions contained herein are the private views of the author, and are not to be construed as official, or as reflecting true views of the Department of the Army or the Department of Defense. RV 144 (3) three years after the V1V2 anti- Copyright: © 2019, American Society for Clinical Investigation. body signal was originally identified as Reference information: J Clin Invest. 2019;129(11):4572–4573. https://doi.org/10.1172/JCI132440. the primary correlate of reduced risk of 4572 jci.org Volume 129 Number 11 November 2019 The Journal of Clinical Investigation COMMENTARY HIV-1 infection in RV 144 (4). Rouphael et (9), and other infectious diseases of public Research, 503 Robert Grant Avenue, Sil- al. did not observe any significant reacto- health importance. ver Spring, Maryland 20910, USA. Phone: genicity to any of the vaccine treatments Second, Rouphael and colleagues have 301.319.7312; Email: nelson.l.michael2. in the study volunteers, implying a favor- defined a pathway to build on the only HIV [email protected]. able safety profile. DNA-HIV-PT123 prim- vaccine study to date associated with signs ing appeared to provide similar immune of clinical efficacy using a genetic vaccine 1. Rerks-Ngarm S, et al. Vaccination with ALVAC responses compared to those seen with type that is far more readily available to a and AIDSVAX to prevent HIV-1 infection in Thai- ALVAC vCP1521 priming in RV 144 (4). wide range of investigators than the devel- land. N Engl J Med. 2009;361(23):2209–2220. Early coadministration of vaccines, as opment of complex viral vectors that are fre- 2. Rouphael NG, , et al. DNA priming and gp120 in the T4 arm, was superior in terms of quently restricted by manufacturer protec- boosting induces HIV-specific antibodies the kinetics of development of Env- and tion of their product development portfolios. in a randomized clinical trial. J Clin Invest. 2019;129(11):4769–4785. V1V2 scaffold–binding antibodies, nAbs While individual DNA plasmid expression 3. Gottardo R, et al. Plasma IgG to linear epi- able to neutralize tier 1 viruses, which are backbones may also be constrained by these topes in the V2 and V3 regions of HIV-1 gp120 relatively easy to neutralize, and ADCC. provisions, the general availability of these correlate with a reduced risk of infection in Together, the results of this trial provide vectors allows for a broader base of inves- the RV144 vaccine efficacy trial. PLoS ONE. three important lessons for the field of tigator-initiated preclinical studies (10), 2013;8(9):e75665. 4. Haynes BF, et al. Immune-correlates analysis HIV vaccine development. directly underpinning the vital innovation of an HIV-1 vaccine efficacy trial. N Engl J Med. that comes from academic investigators. 2012;366(14):1275–1286. Lessons learned and future Third, while many in the field remain 5. Rolland M, et al. Increased HIV-1 vaccine effica- directions skeptical about the possibility that HIV cy against viruses with genetic signatures in Env First, Rouphael et al. effectively contrasted vaccines that fail to elicit potent, broadly V2. Nature. 2012;490(7420):417–420. 6. Zolla-Pazner S, Gilbert PB. Revisiting the differences in immunogenicity between cross-reactive nAbs could ever be an effec- the correlate of reduced HIV infection the RV 144 regimen and correlates of risk of tive public health tool to control the HIV risk in the Rv144 vaccine trial. J Virol. infection from Haynes et al. (4), viral sieve pandemic, additional approaches to drive 2019;93(17):e00629-19. analysis first reported by Rolland et al. (5), heterologous prime-boost vaccines that gen- 7. Korber B, Hraber P, Wagh K, Hahn BH. Polyva- and the gravamen of the work done from erate both functional T cell (11) and nonneu- lent vaccine approaches to combat HIV-1 diver- sity.