Impact of anti-PD-1 and anti-CTLA-4 on the HIV reservoir in people living with HIV with cancer on antiretroviral therapy: The AIDS Malignancy Consortium-095 study

BACKGROUND

Antibodies to PD-1 and CTLA-4 may perturb HIV persistence during antiretroviral therapy (ART) by reversing HIV-latency and/or boosting HIV-specific immunity leading to clearance of infected cells. We tested this hypothesis in a clinical trial of anti-PD-1 alone or in combination with anti-CTLA-4 in people living with HIV (PLWH) and cancer.

METHODS

This was a substudy of the AIDS Malignancy Consortium-095 Study. ART-suppressed PLWH with advanced malignancies were assigned to nivolumab (anti-PD-1) with or without ipilimumab (anti-CTLA-4). In samples obtained pre-infusion and one and seven days after the first and fourth dose of immune checkpoint blockade (ICB), we quantified cell-associated unspliced (CA-US) HIV-RNA and HIV-DNA. Plasma HIV-RNA was quantified during the first treatment cycle. Quantitative viral outgrowth assay (QVOA) to estimate the frequency of replication-competent HIV was performed before and after ICB for participants with samples available.

RESULTS

Of forty participants, 33 received nivolumab and seven nivolumab plus ipilimumab. Whereas CA-US HIV RNA did not change with nivolumab monotherapy, we detected a median 1.44 fold-increase (IQR 1.16-1.89) after the first dose of nivolumab and ipilimumab combination therapy (P=0.031). There was no decrease in the frequency of cells containing replication-competent HIV, but in the two individuals on combination ICB for whom we had longitudinal QVOA, we detected decreases of 97% and 64% compared to baseline.

CONCLUSION

Anti-PD-1 alone showed no effect on HIV-latency or the latent HIV-reservoir, but the combination of anti-PD-1 and anti-CTL-4 induced a modest increase in CA-US HIV RNA and may potentially eliminate cells containing replication-competent HIV.

HIV-1 persistence following extremely early initiation of antiretroviral therapy (ART) during acute HIV-1 infection: An observational study

BACKGROUND

It is unknown if extremely early initiation of antiretroviral therapy (ART) may lead to long-term ART-free HIV remission or cure. As a result, we studied 2 individuals recruited from a pre-exposure prophylaxis (PrEP) program who started prophylactic ART an estimated 10 days (Participant A; 54-year-old male) and 12 days (Participant B; 31-year-old male) after infection with peak plasma HIV RNA of 220 copies/mL and 3,343 copies/mL, respectively. Extensive testing of blood and tissue for HIV persistence was performed, and PrEP Participant A underwent analytical treatment interruption (ATI) following 32 weeks of continuous ART.

METHODS AND FINDINGS

Colorectal and lymph node tissues, bone marrow, cerebral spinal fluid (CSF), plasma, and very large numbers of peripheral blood mononuclear cells (PBMCs) were obtained longitudinally from both participants and were studied for HIV persistence in several laboratories using molecular and culture-based detection methods, including a murine viral outgrowth assay (mVOA). Both participants initiated PrEP with tenofovir/emtricitabine during very early Fiebig stage I (detectable plasma HIV-1 RNA, antibody negative) followed by 4-drug ART intensification. Following peak viral loads, both participants experienced full suppression of HIV-1 plasma viremia. Over the following 2 years, no further HIV could be detected in blood or tissue from PrEP Participant A despite extensive sampling from ileum, rectum, lymph nodes, bone marrow, CSF, circulating CD4+ T cell subsets, and plasma. No HIV was detected from tissues obtained from PrEP Participant B, but low-level HIV RNA or DNA was intermittently detected from various CD4+ T cell subsets. Over 500 million CD4+ T cells were assayed from both participants in a humanized mouse outgrowth assay. Three of 8 mice infused with CD4+ T cells from PrEP Participant B developed viremia (50 million input cells/surviving mouse), but only 1 of 10 mice infused with CD4+ T cells from PrEP Participant A (53 million input cells/mouse) experienced very low level viremia (201 copies/mL); sequence confirmation was unsuccessful. PrEP Participant A stopped ART and remained aviremic for 7.4 months, rebounding with HIV RNA of 36 copies/mL that rose to 59,805 copies/mL 6 days later. ART was restarted promptly. Rebound plasma HIV sequences were identical to those obtained during acute infection by single-genome sequencing. Mathematical modeling predicted that the latent reservoir size was approximately 200 cells prior to ATI and that only around 1% of individuals with a similar HIV burden may achieve lifelong ART-free remission. Furthermore, we observed that lymphocytes expressing the tumor marker CD30 increased in frequency weeks to months prior to detectable HIV-1 RNA in plasma. This study was limited by the small sample size, which was a result of the rarity of individuals presenting during hyperacute infection.

CONCLUSIONS

We report HIV relapse despite initiation of ART at one of the earliest stages of acute HIV infection possible. Near complete or complete loss of detectable HIV in blood and tissues did not lead to indefinite ART-free HIV remission. However, the small numbers of latently infected cells in individuals treated during hyperacute infection may be associated with prolonged ART-free remission.

Polymerous Leaf Whorls in Vascular Plants: Developmental Morphology and Fuzziness of Organ Identities

In vascular plants there are at least eight ways to develop polymerous whorls, i.e., whorls with four or more leaves. Six ways are presented and compared with literature to estimate organ identity (morphological significance) of the leaflike whorl members. New shoots (also seedlings) may start with dimerous or trimerous whorls. Then leaf number per whorl rises as follows: (1) Many taxa add more leaves per whorl continuously with increasing size of the apical meristem (e.g., Equisetum, Hippuris). (2) Taxa provided with interpetiolar stipules replace their stipules by leaves (e.g., Galium and allies). (3) Taxa with the capacity to form compound leaves shift basal leaflets around the whole node (e.g., Limnophila, probably also Ceratophyllum). Various whorled plants start shoot development with leaf inception along a helix, which is continued into the whorled region. Then polymerous whorls develop as follows: (4) Acacia longipedunculata forms helically arranged fascicles instead of single leaves before the production of complete whorls. (5) Acacia baueri and Acacia verticillata add supernumerary leaves between a first series of helically arranged leaves. (6) Hydrothrix produces an annular bulge around the node of each first-formed leaf. All additional leaves of a whorl arise on this annular bulge. Leaf identity of whorl members cannot be defined unequivocally in whorls with asynchronous (i.e., nonsimultaneous) development, dorsoventral distribution of lateral buds, and/or fewer vascular traces than leaves per node. It is heuristically stimulating to accept structural categories (e.g., shoot, leaf, leaflet, stipule) as fuzzy concepts, as developmental pathways that may overlap to some degree, leading to developmental mosaics (intermediates). For example, the whorled leaves of Utricularia purpurea resemble whole shoots, corroborating Arber's partial-shoot theory.

The architecture of Mourera fluviatilis (Podostemaceae): developmental morphology of inflorescences, flowers, and seedlings

Mourera fluviatilis from northern South America is a spectacular member of the Podostemaceae (river-weeds). Its raceme-like inflorescences are up to 64 cm long and have 40-90 flowers arranged in two opposite rows. Inflorescence development starts with the initiation of a double-sheathed (dithecous) bract in a terminal position. All lateral bracts (again dithecous) are initiated in basipetal order along the two flanks of the inflorescence. Each gap between two neighboring bracts contains a single flower. The flowers are bisexual, each with a whorl of 16-20 ligulate tepals and 14-40 stamens, which are arranged in one or two whorls. Floral development starts with the formation of a girdling primordium rim around a two-lobed primordial gynoecium. Stamen and tepal initiation is centrifugal on the girdling primordium. The anthers are introrse or extrorse, depending on stamen position. Seedlings develop two entire, threadlike cotyledons, followed by forked filamentous leaves, which arise from the plumular pole. The radicular pole of the hypocotyl develops into a claw-shaped holdfast that fixes the young plant to the rock. The developmental morphologies of Mourera fluviatilis and other members of the Mourera group (including Lonchostephus and Tulasneantha) fit well with the Podostemoideae bauplan known from other New World genera, such as Apinagia and Marathrum.