AVT001 (spHsp60-pulsed autologous dendritic cells)

Overview

AVT001 is an autologous dendritic cell immunotherapy developed by Avotres Inc. based on foundational immunology research by Drs. Hong Jiang and Leonard Chess at Columbia University (PMID: 20877010). Whereas most regulatory T-cell therapies focus on classical CD4+ Foxp3+ Tregs, AVT001 targets a distinct peripheral self-tolerance checkpoint mediated by non-classical MHC class Ib (Qa-1 in mice / HLA-E in humans)-restricted CD8+ regulatory T cells (HLA-E CD8+ Tregs).

During T-cell activation, intermediate-avidity self-reactive T cells upregulate surface complexes of HLA-E bound to a nine-amino-acid hydrophobic leader peptide derived from heat shock protein 60 (spHsp60). HLA-E-restricted CD8+ Tregs recognize this HLA-E/spHsp60 complex and selectively eliminate or inhibit activated pathogenic autoreactive T cells while sparing low-avidity naive T cells and high-avidity pathogen-specific T cells. In a majority of people with Type 1 Diabetes, this HLA-E CD8+ Treg pathway is functionally defective (PMID: 20877010).

To manufacture AVT001, peripheral blood monocytes are collected from the patient via leukapheresis, differentiated ex vivo into immature dendritic cells, and pulsed with synthetic spHsp60 peptide. Because HLA-E is virtually monomorphic across human populations (with only two functionally similar alleles worldwide), a single standardized spHsp60 peptide works across patients regardless of their classical HLA-DR or HLA-DQ genotype.

Key Clinical Evidence

Randomized Phase 1/2 Trial at Joslin Diabetes Center (NCT03895996, NEJM Evidence 2024)

In the randomized, double-blind, placebo-controlled Phase 1/2 trial NCT03895996 (published by Gaglia et al. in NEJM Evidence in July 2024, PMID: 38916421), 25 participants aged 16 and older within 1 year of Stage 3 T1D diagnosis with residual C-peptide were randomized approximately 2:1 to receive three monthly intravenous infusions of AVT001 (n = 16) or matched placebo (n = 9) at Cellular Therapy labs of Dana-Farber / Joslin Diabetes Center, with primary analysis at Day 150 (5 months post-first dose) and supplemental follow-up through Day 360:

• Primary Safety Outcomes: AVT001 met all primary safety endpoints. There were zero serious adverse events (0 SAEs), zero local intravenous-site reactions (0/16 vs 0/9), and no clinically meaningful changes in hepatic (ALT -0.1 ± 5.2 U/L, AST -1.9 ± 7.8 U/L, bilirubin -0.11 ± 4.06 µmol/L) or renal (creatinine) laboratory parameters. All 16 AVT001 recipients completed the full Day 360 follow-up (16/16), compared with 8/9 in the placebo group.
• Mechanistic Target Engagement (HLA-E CD8+ Treg Potency Assay): In the functional CD8+ T-cell inhibition assay posted on ClinicalTrials.gov, baseline HLA-E CD8+ Treg inhibition in the AVT001 group was defective at -11.2% ± 9.9% and rose to +9.3% ± 24.9% at Day 150, compared with 3.5% ± 7.1% at baseline and 1.8% ± 15.1% at Day 150 in the placebo group — confirming in vivo restoration of the targeted regulatory pathway.
• Metabolic Preservation (4-Hour MMTT C-Peptide AUC):
  • On the raw ClinicalTrials.gov results scale (nmol/L), mean 4-hour MMTT stimulated C-peptide AUC in the AVT001 arm (n = 16) went from 0.531 ± 0.363 nmol/L at baseline to 0.518 ± 0.430 nmol/L at Day 150 (-2.4% mean change), whereas the placebo arm (n = 9) declined from 0.611 ± 0.178 nmol/L at baseline to 0.472 ± 0.134 nmol/L at Day 150 (-22.7% mean decline).
  • On the prespecified longitudinal mixed-model analysis of log-transformed C-peptide AUC (PMID: 38916421), the estimated treatment difference in change from baseline to Day 150 favored AVT001 by +0.09 (95% CI, 0.03 to 0.15), with less C-peptide decline maintained through Day 360 while both arms targeted standard glycemic control (70–180 mg/dL [3.9–10.0 mmol/L]; Day 150 HbA1c 6.15% ± 0.85% in AVT001 vs 5.82% ± 0.84% in placebo).
  • Exploratory subgroup analyses indicated the strongest C-peptide preservation in participants treated earlier with higher baseline C-peptide and lower baseline insulin requirements.

Limitations & Watch Items

1. Waning Off-Treatment Effect: Because AVT001 was administered only at Months 0, 1, and 2, the C-peptide trajectory and CD8+ Treg potency began to attenuate between Day 150 and Day 360. Future Phase 2b protocols will likely need quarterly or semiannual maintenance booster infusions (readily thawed from cryopreserved aliquots of the initial leukapheresis batch).
2. Sample Size & Next Trial Registration: While NCT03895996 was randomized, double-blind, and placebo-controlled, n = 25 is an early proof-of-concept sample size; registration of a larger multi-center Phase 2b trial is the key next milestone.

Summary of Strengths & Limitations

Strengths

• Targets a non-classical monomorphic MHC class Ib pathway (HLA-E), meaning patients do not need to carry specific classical HLA-DR3 or HLA-DR4 alleles to be eligible
• Randomized, double-blind, placebo-controlled Phase 1/2 trial at Joslin Diabetes Center (NCT03895996, n = 25; Gaglia et al., NEJM Evidence 2024) met its primary safety endpoint (0 SAEs) and demonstrated less decline in 4-hour MMTT C-peptide AUC than placebo at Day 150 (+0.09 log C-peptide AUC difference, 95% CI 0.03 to 0.15; raw mean 0.531 to 0.518 nmol/L [-2.4%] on AVT001 vs 0.611 to 0.472 nmol/L [-22.7%] on placebo)
• Ex vivo functional potency assay confirmed restoration of HLA-E-restricted CD8+ Treg inhibitory activity (+9.3% at Day 150 vs -11.2% at baseline in AVT001 recipients) without systemic immunosuppression

Limitations

• {'Small Phase 1/2 sample size (n = 25': '16 AVT001 versus 9 placebo), and no larger Phase 2b or Phase 3 confirmatory trial has yet begun recruiting on ClinicalTrials.gov'}
• Requires patient-specific leukapheresis, ex vivo monocyte-to-dendritic-cell differentiation and peptide pulsing, and three monthly intravenous infusions
• C-peptide preservation gradually waned after the three monthly infusions ended (between Day 150 and Day 360), indicating that periodic maintenance booster infusions or earlier intervention may be needed for durable disease control