temsavir (BMS-626529) / BMS - LARVOL DELTA

Impact of Fostemsavir in Individuals with Multidrug-Resistant HIV-1, Stratified by Baseline Viral Load. (PubMed, Infect Dis Ther) - P3 | "Findings support considering fostemsavir for regimen optimization in individuals with limited treatment options and undetectable/low VL, especially if safety/tolerability may be a concern."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4 • CD8

A French National Real-World Survey of People With Multiresistant HIV-1 Viruses Receiving an Antiretroviral Regimen Including Fostemsavir or Ibalizumab. (PubMed, Open Forum Infect Dis) - "Suboptimal temsavir concentrations were observed in 2 of 8 participants in failure...PWH receiving FTR or IBA had extensive multidrug resistance and limited therapeutic options. Among PWH who were viremic and initiating FTR- and IBA-based regimens, virologic success was achieved in 63% and 36%, respectively, and maintained in 91% who were virologically suppressed and starting an FTR-based regimen."

Journal • Real-world evidence • Human Immunodeficiency Virus • Infectious Disease

Added value of RNA-based whole genome sequencing in viremic people with 4-class drug-resistant HIV: insights from the PRESTIGIO Registry (AIDS 2026) - "Outside pol , WGS (=5%) detected =1 lenacapavir RAM in 7/39 (17.9%) samples [6/7 (85.7%) without prior lenacapavir exposure] and =1 temsavir RAM in 16/39 (41.0%) [12/16 (75.0%) without prior fostemsavir exposure]. Despite some limitations, particularly the limited ability to completely reconstruct cumulative resistance history derived from prior RNA-based Sanger genotypes, RNA-based WGS provided additional, previously unrecognized resistance information, including mutations affecting novel drug targets, in individuals with multidrug-resistant HIV. These findings support the role of WGS as a valuable complementary tool in settings with a high mutational burden."

Tumor mutational burden • Whole genome sequencing • Human Immunodeficiency Virus • Infectious Disease • CD4 • CD8 • TMB

Comprehensive Mapping of the Virus and Host Factors that Guide the Paths of HIV-1 Escape from a Therapeutic. (PubMed, bioRxiv) - "Through comprehensive screening, we identified 18 mutations in the HIV-1 Env protein that enhance resistance to the FDA-approved small-molecule therapeutic temsavir...Notably, non-neutralizing antibodies commonly-elicited in HIV-infected individuals restricted emergence of multiple resistant forms, driving convergence to a narrow set of escape routes. These findings establish a quantitative framework for predicting therapeutic resistance and reveal how host-immunity constrains viral evolution during treatment."

Journal • Human Immunodeficiency Virus • Infectious Disease

Exploring the impact of baseline and on-treatment variables on durability of responses to fostemsavir through weeks 96 and 192 in the phase 3 BRIGHTE study. (PubMed, HIV Med) - "Multivariable analysis (MVA) identified several factors predictive of virologic response. No baseline factors were highly predictive of virologic failure at Weeks 96 or 192. Findings support the use of fostemsavir in diverse populations with MDR HIV-1."

Journal • P3 data • Human Immunodeficiency Virus • Infectious Disease • CD4

A French national real-world survey of people with multi-resistant HIV-1 viruses treated with an antiretroviral regimen including fostemsavir (EACS 2025) - "Temsavir plasma levels were available for 8 PWH, showing suboptimal concentrations in 2. Conclusions : In this real-world study, PWH receiving FTR-based treatment harbored multidrug-resistant viruses and had very limited treatment options. Virological success was achieved in 60% of PWH with quantifiable VL at time of FTR initiation, and success was maintained in 93% of virologically-suppressed PWH."

Clinical • Real-world • Real-world evidence • Human Immunodeficiency Virus • Infectious Disease

7-year sustained efficacy, safety, and immunological improvement with fostemsavir-based regimens in individuals with HIV and limited treatment options (EACS 2025) - "Purpose : Fostemsavir (FTR), a prodrug of temsavir, is a novel antiretroviral with a unique mechanism of action targeting viral-bound gp120 and soluble gp120. Inflammatory biomarkers remained constant from Week 240 to Week 336 in both cohorts in all measured proinflammatory markers (sCD14, sCD163, and D-dimer). Conclusions : These further long-term findings demonstrate that through 7 years, FTR-based regimens had durable efficacy and safety, with prolonged immunological improvement and a generalized reduction in inflammation in individuals with limited treatment options."

Clinical • Human Immunodeficiency Virus • Infectious Disease • CD8

Development, validation and clinical implementation of a HPLC-MS/MS method for the simultaneous quantification of bictegravir, emtricitabine, doravirine, cabotegravir, lenacapavir, fostemsavir, tenofovir alafenamide and the corresponding metabolites temsavir and tenofovir, in human plasma. (PubMed, J Chromatogr B Analyt Technol Biomed Life Sci) - "Additionally, data on drug pharmacokinetics were obtained. Our findings indicate that the proposed method is a reliable and accurate tool for high-throughput screening that could be readily used by the clinicians to optimize therapeutic treatments, verify patients' adherence and reduce drug-related toxicities."

Journal • Human Immunodeficiency Virus • Infectious Disease

HIV subtype-specific gp140-CD4 binding, Temsavir efficacy, and identification of novel adhesion inhibitors against Chinese HIV strains. (PubMed, Front Immunol) - "This study elucidates the molecular mechanisms of HIV-1 adhesion variation and provides specific candidate HIV adhesion inhibitors for prevalent CRF subtypes in China. Subsequent efforts will focus on preclinical validation and structure-activity relationship optimization of these candidates, laying the groundwork for developing personalized therapeutic strategies against region-specific strains."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

Fostemsavir Decreases the Levels of Anti-gp120 CD4-Induced Antibodies in Heavily Treatment-Experienced People With HIV. (PubMed, J Infect Dis) - P, P3 | "Altogether, fostemsavir may provide additional immune benefits to PWH, beyond blocking viral entry, by reducing anti-gp120 CD4i Abs levels."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

Fostemsavir analog BMS-818251 has enhanced viral neutralization potency and similar escape mutation profile. (PubMed, Antimicrob Agents Chemother) - "By using ex vivo viral outgrowth assays with HIV+ donor samples, we demonstrate here that BMS-818251 exhibits superior viral suppression compared to temsavir, the active form of fostemsavir. Compared to fostemsavir, BMS-818251 achieved more effective viral suppression at lower concentrations, even in donor samples harboring preexisting resistance mutations. These findings support the continued development of BMS-818251 as a promising alternative to fostemsavir, with potential benefits for patients with multidrug-resistant HIV-1."

Journal • Human Immunodeficiency Virus • Infectious Disease

Population pharmacokinetics and exposure-response relationship for temsavir following fostemsavir administration in treatment-experienced HIV patients. (PubMed, Pharmacol Res Perspect) - "Both the population PK and E-R models support administration of FTR 600 mg BID to decrease virologic load in HIV-1 HTE patients, with no dose adjustments necessary for coadministration with moderate CYP3A inducers, strong CYP3A inhibitors, prandial status, or body weight. Results from this analysis supported the regulatory approval of the fostemsavir 600 mg dose and are applicable to clinical trial simulations in other scenarios and populations (e.g., pediatrics)."

Journal • PK/PD data • Gastrointestinal Disorder • Human Immunodeficiency Virus • Infectious Disease • Pediatrics

A gp41 HR2 residue modulates the susceptibility of HIV-1 envelope glycoproteins to small molecule inhibitors targeting gp120. (PubMed, J Virol) - "Since residue 629 within the HR2 region of gp41 has also been proposed to have co-evolved with residue 375, we explored its role in the susceptibility of HIV-1 Env to two classes of small molecule gp120 inhibitors: the conformational blocker temsavir and the CD4-mimetic (CD4mc) BNM-III-170...Here, we report that a residue of the gp41 HR2 region affects Env trimer stability and its susceptibility to gp120-directed small molecule inhibitors. This work adds to our understanding of HIV-1 Env resistance to small molecule inhibitors."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

Fostemsavir resistance in clinical context: a narrative review. (PubMed, Ther Adv Infect Dis) - "In the phase III BRIGHTE study, re-suppression after virologic failure was observed in some participants despite treatment-emergent genotypic and/or phenotypic evidence of reduced temsavir susceptibility, and substantial CD4+ T-cell count increases occurred even among participants with HIV-1 RNA ⩾40 copies/mL at Week 240. Clinical management of people who are HTE and experience virologic failure during treatment with fostemsavir-based regimens requires an individualized approach with consideration of potential benefits beyond virologic suppression."

Journal • Review • Human Immunodeficiency Virus • Infectious Disease • CD4

Enhanced Recognition of V3 bNAb Epitopes Induced by Fostemsavir on Cell-Associated Primary HIV-1 Env (CROI 2025) - "It is the prodrug of its active form, temsavir (TMR). Additionally, enhancement of V3 directed bnAb binding after 15 mins of TMR treatment with the RS mutant (gp160), suggests that TMR may directly influence Env conformation rather than indirectly affecting it through processing or glycosylation inhibition. Conclusions These data indicate that FTR does not primarily affect all strains by decreasing Env expression, and may be used in combination with certain V3 bnAb treatments to potentially enhance the effectiveness of bnAb-based therapies."

Human Immunodeficiency Virus • Infectious Disease • CD4

Temsavir Treatment Improves Recognition of HIV-1 Infected Cells by Broadly Neutralizing Antibodies (CROI 2025) - "TMR is the active form of fostemsavir (FTR), a drug approved for use in heavily treatment-experienced adults with multidrug-resistant HIV-1 infection. Conclusions Our results demonstrate that TMR treatment enhances antibody binding to the infected cells that maintain CD4 expression with a majority of bnAbs, at concentrations similar to the antiviral potency of TMR. These suggest that combining bnAbs with TMR can broaden the range of HIV-1 infected cells susceptible to antibody-mediated clearance, potentially increasing the likelihood of reservoir reduction in clinical settings."

Human Immunodeficiency Virus • Infectious Disease • CD4

Investigating the combination of Temsavir and entry inhibitors on HIV replication: Synergistic and antagonistic effects observed against various R5-tropic envelopes. (PubMed, Virology) - "Here, we investigated the effects of combining Temsavir with other HIV entry inhibitors, including CD4 mimetic BNM-III-170, T20 or enfuvirtide, Ibalizumab, and Maraviroc. These results are promising for the potential of co-administrating antiretrovirals for HIV treatment and highlights the importance of developing advanced antiviral strategies. On the other hand, the variable responses against different R5-tropic envelopes underscore the complexity of designing universally effective combination antiviral therapies."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

CD4 T‐cell, CD4/CD8 ratio improvement and a general reduction in inflammatory biomarkers with low‐ level viraemia (LLV) up to week 192 with fostemsavir (FTR)‐based regimens in individuals with multidrug‐resistant (MDR) HIV‐1 (HIV-Glasgow 2024) - "FTR (prodrug of the first-in-class attachment inhibitor temsavir) is indicated with other antiretrovirals (ARVs) for heavily treatment-experienced individuals with MDR HIV-1 unable to construct suppressive regimens. In participants with LLV, there is a persistent increase in CD4 T-cell count and improvement in CD4/CD8 ratio, with a general reduction in inflammatory markers up to week 192. Results highlight the value of FTR-based regimens for sustained improvement where there is incomplete virological suppression."

Biomarker • Clinical • Human Immunodeficiency Virus • Infectious Disease • Inflammation • CD4 • CD8

No dose adjustment of metformin or substrates of organic cation transporters (OCT)1 and OCT2 and multidrug and toxin extrusion protein (MATE)1/2K with fostemsavir coadministration based on modeling approaches. (PubMed, Pharmacol Res Perspect) - "Hence, a physiologically based pharmacokinetic (PBPK) model of fostemsavir/temsavir was developed to further assess the DDI risk potential of OCT and MATEs inhibition by temsavir and predict changes in metformin (a sensitive OCT and MATEs substrate) exposure. No clinically relevant impact on metformin concentrations across a wide range of temsavir concentrations was predicted; therefore, no dose adjustment is recommended for metformin when co-administered with fostemsavir."

Journal • Human Immunodeficiency Virus • Infectious Disease

Characterization of Clinical Envelopes With Lack of Sensitivity to the HIV-1 Inhibitors Temsavir and Ibalizumab. (PubMed, Antiviral Res) - "Previous data suggest a lack of cross-resistance between the gp120-directed attachment inhibitor temsavir (active moiety of fostemsavir) and the CD4-directed post-attachment inhibitor ibalizumab. Interestingly, introduction of the gp120 V5 region from a highly ibalizumab-susceptible envelope mitigated the E202 effect on ibalizumab but not temsavir. A rare HIV-1 gp120 E202 mutation reduced temsavir susceptibility, and depending on sequence context, could result in reduced susceptibility to ibalizumab."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

The Sensitivity of HIV-1 gp120 Polymorphs to Inhibition by Temsavir Correlates to Temsavir Binding On-rate. (PubMed, Antiviral Res) - "Loss of susceptibility to temsavir observed for gp120 polymorphisms strongly correlated with reductions in temsavir binding on-rate. Nonetheless, temsavir retained the ability to fully block CD4-gp120 engagement given sufficiently high concentrations."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

Development of a physiologically based pharmacokinetic model of fostemsavir and its pivotal application to support dosing in pregnancy. (PubMed, CPT Pharmacometrics Syst Pharmacol) - "Fostemsavir (FTR) is a prodrug of temsavir (TMR) and is approved in combination with other antiretrovirals for multi-drug-resistant human immunodeficiency virus (HIV) infections. However, TMR exposure remained within the range observed in nonpregnant adults with no need for dose adjustment. The current PBPK model can also be applied for the prediction of local tissue concentrations and drug-drug interactions in pregnancy."

Journal • PK/PD data • Human Immunodeficiency Virus • Infectious Disease

Temsavir Treatment Enhances bNAb Recognition and Subsequent Clearance of HIV-1–Infected Cells (CROI 2024) - "Temsavir (TMR), the active form of the HIV-1 attachment inhibitor fostemsavir, binds to and stabilizes Env in a 'closed' conformation that may allow better targeting by broadly neutralizing antibodies (bnAbs).To understand whether TMR can modulate bnAb binding to Env on the infected cells, we conducted experiments with primary CD4+T cells isolated from HIV negative donors infected with a broad panel of viruses that includes 26 clinical HIV isolates. We have demonstrated for the majority of viruses tested that TMR treatment leads to enhanced bnAb binding to the infected cells that maintain CD4 expression, and the reduced bnAb binding to the CD4 downregulated infected cells occurs at much higher concentrations than neutralization. These results suggest that combination of bnAb and TMR can expand the population of HIV-1 infected cells susceptible to bnAb mediated clearance and may increase the likelihood of reservoir reduction in the clinical setting."

Human Immunodeficiency Virus • Infectious Disease • CD4

Structure-function analyses reveal key molecular determinants of HIV-1 CRF01_AE resistance to the entry inhibitor temsavir. (PubMed, Nat Commun) - "A detailed structure-function analysis using engineered viruses and soluble trimer variants reveals that the molecular basis of resistance is mediated by crosstalk between His375 and the inner domain layers. Furthermore, our data confirm that temsavir can adjust its binding mode to accommodate changes in Env conformation, a property that likely contributes to its broad antiviral activity."

Journal • Human Immunodeficiency Virus • Infectious Disease • CD4

Clinical Data from the GP120 Inhibitor Temsavir and Its Potential Relevance to Immune Reconstitution and HIV Associated Inflammation (EACS 2023) - "Sponsored by Virology Education"

Clinical data • Human Immunodeficiency Virus • Infectious Disease