CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

686

Virologic Failure With Cabotegravir-Rilpivirine Injections: A Single-Site Experience Shivanjali Shankaran, Laura Hernandez-Guarin, Neel Jhobalia, Beverly Sha, Mariam Aziz Rush University Medical Center, Chicago, IL, USA Background: Cabotegravir-rilpivirine (CAB-RPV), the first intramuscular injectable antiretroviral therapy (ART) for people with HIV, is associated with high compliance rates and patient satisfaction. Multiple studies demonstrate low rates of virologic failure (VF) and development of resistance, confirmed by real world analyses. Here we describe our experience with a higher rate of VF at an HIV clinic in Chicago, IL. Methods: We assessed baseline viral loads (VL) at time of switch in ART, clinic location for the injections and response after transitioning to CAB-RPV. VF was defined as two consecutive VL >200 copies/ml. Resistance mutations in patients with VF were recorded. Results: 75 undetectable patients (UD, VL <40 copies/ml) were switched to CAB-RPV. 10 received their injections at an independent infusion center (IC) with trained injectors. 65 received injections at our clinic. Two of ten patients at IC and 1 of 65 patients at our clinic developed virologic failure (4%). One patient (pt1) had non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance (K103N), the second (pt2) had an M184V while a genotype failed for the third patient (pt3) at the time of diagnosis. Patients had lived with HIV for 23, 18 and 1 year, respectively, before switch and were lifelong nonsmokers. Pt1 was UD for 2 months and the other two were UD for >6 months prior to switch. All were on an integrase inhibitor (INI) based regimen. Body mass index (BMI) were 27, 35 and 28 respectively. The patients were UD for 6, 10 and 18 months respectively on CAB-RPV before VF. Genotypes at the time of VF revealed INI mutations in pt1: L74I, T97T/A, S147S/G, N155H, INI and NNRTI mutations in pt2: L74L/M, T97T/A, G140S, Q148H and K101E, E138K, I178L, Q207E and INI mutations in pt3: G140G/S, Q148Q/R. None had a missed or delayed dose of CAB-RPV. 1.5-inch needles were used in all three. The two IC patients raised concerns about irregular injection techniques. All three switched to a protease inhibitor-based regimen and were subsequently UD. Conclusion: While injectable ART are revolutionary in HIV care, clinicians should be aware of possible higher real-world failure rates due to nonstandard injection practices, smoking status, high BMI or unknown pre-existing resistance mutations. Ensuring appropriate training for injecting staff, use of longer needles and obtaining HIV-1 proviral DNA resistance assays may be considered prior to switching to CAB-RPV to further decrease the risk of VF. Env Conformational Flexibility Modulates HIV-1 Sensitivity to VRC01-Mediated Prevention Durgadevi Parthasarathy 1 , Karunakar R. Pothula 2 , Ruth Parsons 2 , Xiao Huang 2 , Salam Sammour 2 , Katarzyna Janowska 2 , Miranda Harris 1 , Joseph Sodroski 3 , Priyamvada Acharya 4 , Alon Herschhorn 1 1 University of Minnesota, Minneapolis, MN, USA, 2 Duke Human Vaccine Institute, Durham, NC, USA, 3 Dana–Farber Cancer Institute, Boston, MA, USA, 4 Duke University, Durham, NC, USA Background: HIV-1 envelope glycoproteins (Envs) mediate viral entry and are the sole target of neutralizing antibodies. Envs of most primary HIV-1 strains exist in a closed conformation and occasionally sample more open Env states. Thus, current knowledge guides immunogen design to mimic the closed Env conformation as the preferred target for eliciting broadly neutralizing antibodies (bnAbs) to block HIV-1 entry. Methods: We evaluated the conformational state of transmitted/founder (T/F) HIV-1 Envs on infectious virions by measuring HIV-1 sensitivity to: 1) antibodies that target internal epitopes, 2) bnAbs, 3) soluble CD4 (sCD4), and 4) exposure to cold. Recognition of soluble HIV-1 Envs (gp120) and surface-expressed Envs by antibodies was measured by ELISA and flow cytometry, respectively. We solved the cryo-EM structure of an unliganded T/F Envs (1059-SOSIP) at 3.6 Å resolution using a large data set and analyzed sub-class structures to estimate the heterogeneity of Env conformations. Results: We identified T/F HIV-1 Envs that are incompletely closed and sensitive to antibodies that target internal epitopes, to sCD4, and to cold exposure. A cryo-electron microscopy structure of unliganded, incompletely closed T/F Envs (1059-SOSIP), which is resistant to VRC01, at 3.6 Å resolution exhibits an asymmetric configuration of Env protomers with increased sampling of states with incompletely closed trimer apex. We further show a correlation between efficient neutralization of multiple Env conformations and increased antiviral breadth of CD4-binding site (CD4bs) bnAbs. In particular, N6 CD4bs bnAb, which

Results: R263K mutation had a major effect on reverse transcription (Figure 1A and B) and a weaker impact on integration. N155H mutation strongly affected reverse transcription (Figure 1A and B) and integration. The G140S/ Q148H double mutant profile was associated with a weak impact on reverse transcription (Figure 1A and B) and a more important impact on integration compared to WT. Conclusion: INSTI resistance mutations alter integration efficiency but also the reverse transcription step. This phenomenon is in accordance with the close interaction between these two enzymes during HIV-1 replication. These observations might contribute to explain the loss of fitness observed in INSTI resistant mutants during virological failure.

Poster Abstracts

685

High-Level Resistance to Integrase Inhibitors Conferred by Mutations Outside Integrase Yuta Hikichi, Sherimay D. Ablan, Erin Clark, Eric O Freed National Cancer Institute, Frederick, MD, USA Background: Second-generation integrase (IN) strand transfer inhibitors (INSTIs) are highly potent antiretroviral compounds that exhibit a high genetic barrier to resistance. Recent clinical studies concluded that some INSTI-treated individuals experience virological failure in the absence of resistance mutations in IN. The aim of the study is to elucidate INSTI resistance mechanisms and pathways. Methods: One-year passaging of HIV-1 was conducted using the SupT1 T-cell line and primary PBMCs with an escalating concentration of the INSTI dolutegravir (DTG). We evaluated the impact of the selected mutations on replication kinetics and viral infection through cell-free virion and cell-cell contact and performed an array of biochemical and structural analyses on the selected mutants. Results: HIV-1 became resistant to DTG by sequentially acquiring mutations in Env, Gag-nucleocapsid (NC), and, occasionally, IN. By cloning env from the DTG-treated viruses selected in the SupT1 T-cell line or PBMC, we obtained heavily mutated Env clones, 7XEnv and WD-3, respectively. Both Env mutants exhibit faster-than-WT replication in spreading infection. 7XEnv exhibits resistance to multiple classes of antiretrovirals, with the fold resistance being ~2-logs higher for INSTIs than for other classes of drugs. WD-3 confers 5-fold resistance to DTG in PBMC. Viral transmission of 7XEnv through cell-cell contact is more efficient than that of WT. In contrast, WD-3 exhibits more efficient cell-free infection than WT. These results suggest that the selected Env mutations confer resistance to INSTIs by increasing infection capacity through cell-cell transmission or cell-free viral infection. Viral infection over a range of multiplicities of infection (MOI) revealed that INSTIs are more readily overwhelmed by high MOI than other classes of drugs, leading to high-level resistance to INSTIs. The NC mutations selected with DTG conferred modest (3-5 fold) resistance to INSTIs. Significantly, the NC mutations do not affect cell-free infectivity but accelerate the kinetics of early post-entry events, suggesting that they may limit the window of opportunity for INSTIs to bind intasomes and block integration. Conclusion: These findings demonstrate that multiple regions in the HIV-1 genome – Env, NC, and IN – collectively contribute to INSTI resistance. The results provide clues to understanding high-level resistance to INSTIs and support the need for genotypic analysis outside of IN in individuals on INSTI containing regimens.

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CROI 2024 199