On May 21, 2026 Aulos Bioscience, a clinical-stage immuno-oncology company developing an immune-activating antibody therapeutic designed by leveraging an AI platform, reported positive Phase 2 data from its ongoing Phase 1/2 study of imneskibart in patients with doublet checkpoint inhibitor (CPI)-refractory metastatic melanoma. The data will be presented in a poster session at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 2026 Annual Meeting in Chicago, Illinois.
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The Phase 2 data show that imneskibart-based outpatient regimens are well tolerated and demonstrate durable clinical activity, including ongoing and deepening responses. Patients received either imneskibart plus low-dose, subcutaneous aldesleukin or the triplet regimen of imneskibart plus low-dose, subcutaneous aldesleukin and nivolumab. Across the study, imneskibart treatment was associated with sustained regulatory T cell (Treg) reduction, increased CD8/Treg ratios and evidence of durable anti-tumor activity, supporting its differentiated IL-2 mechanism.
"Imneskibart’s triplet regimen produced a 33% objective response rate and 67% disease control rate in metastatic melanoma patients whose disease progressed following earlier treatment with potent checkpoint inhibitor doublets," said Aron Knickerbocker, Aulos Bioscience’s President and Chief Executive Officer. "These patients urgently need safe, life-extending treatment options, particularly those who are not eligible for or do not receive TIL therapy. While lifileucel TIL therapy is the only FDA-approved product specifically indicated in the post-PD-1 setting, a substantial treatment gap remains. In addition to durable efficacy consistent with anti-tumor immune memory formation, imneskibart continues to demonstrate a differentiated, potentially best-in-class safety profile. These findings strongly support imneskibart’s mechanism and its ability to make a meaningful difference for patients."
As of the April 6, 2026 data cutoff, data were available from 83 patients across the Phase 1/2 study, including 12 patients in the Phase 2 melanoma triplet cohort evaluable for response:
Clinically meaningful activity observed with imneskibart triplet in doublet CPI-refractory melanoma
33% objective response rate (ORR) in confirmed doublet CPI-refractory cutaneous melanoma patients following prior anti-PD-1/CTLA-4 or anti-PD-1/LAG-3 therapy.
Four of 12 patients achieved partial responses, with target tumor reductions of 52%, 65%, 74% and 77%.
Four of 12 patients achieved stable disease, resulting in a 67% disease control rate.
Responses are ongoing and deepening, consistent with the potential generation of de novo anti-tumor immunity and immune memory formation; progression-free survival (PFS) and overall survival (OS) data continue to mature.
Strong signal of anti-tumor activity in imneskibart doublet regimen, with ongoing deep and durable tumor reductions in patients who progressed after receiving doublet CPI therapy (prior anti-PD-1 and anti-CTLA-4 and/or anti-PD-1 and anti-LAG-3)
14 evaluable patients received the imneskibart doublet regimen.
Three patients with the deepest target tumor reductions continued treatment beyond one year: one patient with a 48% tumor reduction continued on treatment for 13 months; another patient with a 58% reduction in measurable non-target tumors continued on treatment for 18.5 months; and a third patient with a complete response (100% reduction) in the target lesions continues on treatment for more than 25 months.
Imneskibart and low-dose, subcutaneous aldesleukin, with or without nivolumab, exhibits unique pharmacodynamic (PD), biological and pharmacokinetic (PK) effects in the IL-2 class, with a higher peripheral blood CD8/Treg ratio correlating with increased survival
Durable increases in CD8+ T cells and CD8/Treg ratios were observed in patients, with a corresponding decrease in Tregs.
PD data support hypothesis of selective effector cell expansion, validating imneskibart’s mechanism of action of redirecting interleukin-2 (IL-2) away from trimeric IL-2 receptors (expressed on Tregs and vasculature) and toward dimeric IL-2 receptors (on CD8+ T effector and natural killer cells).
The data show that imneskibart demonstrates durable activity coupled with a persistent reduction in Tregs and a higher CD8/Treg ratio that is associated with longer OS, PFS and time on treatment for patients.
PK data demonstrate sustained, selective signaling with a half-life of greater than 19 days, enabling potent immune activation without Treg expansion or high-dose IL-2 toxicities such as vascular leak syndrome or pulmonary edema.
Well-tolerated triplet regimen, with no apparent increase in Grade 3/4 adverse events following addition of nivolumab
Most drug-related adverse events were Grade 1 or 2; no patient discontinued treatment due to a drug-related adverse event.
The emerging safety profile of the triplet regimen is consistent with the known safety profiles of nivolumab and imneskibart plus aldesleukin, with no new toxicity signals observed.
Enrollment is complete in the Phase 2 doublet cohort evaluating imneskibart plus a single loading dose of low-dose, subcutaneous aldesleukin in patients with unresectable locally advanced or metastatic cutaneous melanoma following confirmed progression on doublet CPI therapy. Enrollment continues in the Phase 2 triplet cohort evaluating imneskibart plus low-dose, subcutaneous aldesleukin and nivolumab in approximately 20 evaluable second-line cutaneous melanoma patients, with plans advancing toward potential registrational development.
Two ongoing Phase 2 cohorts are evaluating imneskibart and low-dose, subcutaneous aldesleukin administered without and with avelumab (anti-PD-L1 with an active Fc domain and ADCC effector function) in patients with advanced PD-L1+ non-small cell lung cancer (NSCLC) that progressed on prior CPI therapy (with or without chemotherapy). Aulos anticipates presenting comprehensive clinical data from the NSCLC Phase 2 cohorts by year-end.
The poster, "Imneskibart + low-dose subcutaneous IL-2 ± nivolumab in patients with CPI-refractory cutaneous melanoma: Promising results from an ongoing phase 1/2 study," (Abstract 9526) will be presented live in the poster session "Melanoma/Skin Cancers" in the Exhibit Hall at McCormick Place on Sunday, May 31, 2026, 9:00 a.m. to 12:00 p.m. CDT. The poster will also be accessible to meeting registrants as an electronic poster on the ASCO (Free ASCO Whitepaper) online meeting platform.
To learn more about the imneskibart clinical trial program, please visit ClinicalTrials.gov (identifier: NCT05267626). For patients and providers in the U.S., please visit www.solidtumorstudy.com. For patients and health professionals in Australia, please visit www.solidtumourstudy.com.
About Imneskibart
Imneskibart (AU-007) is a human IgG1 monoclonal antibody designed by leveraging artificial intelligence that is highly selective to the CD25-binding portion of IL-2. With a mechanism of action unlike any other IL-2 therapeutic in development, imneskibart redirects IL-2 to reinforce anti-tumor immune effects. This is achieved by preventing IL-2, either exogenous or secreted by effector T cells, from binding to trimeric receptors on regulatory T cells while still allowing IL-2 to bind and expand effector T cells and NK cells. This prevents the negative feedback loop caused by other IL-2-based treatments and biases the immune system toward activation over suppression. Imneskibart also prevents IL-2 from binding to CD25-containing receptors on eosinophils, as well as vasculature and pulmonary endothelium, which may significantly reduce the vascular leak syndrome and pulmonary edema associated with high-dose IL-2 therapy.
(Press release, Aulos Bioscience, MAY 21, 2026, View Source [SID1234665916])