Personalized Multipeptide Cancer Vaccine Activates T Cells in 95% of Leukemia Patients | Research

The takeaway

iTAC-XS15-CLL01 personalized multipeptide T-cell activator induced T-cell responses in 95% of CLL patients, with responses persisting at 6 months and manageable injection-site adverse events.

95% immunogenicity
19 of 20 CLL patients developed T-cell responses to the personalized peptide vaccine, with responses growing stronger over time

What the researchers found

T-cell response in 19/20 patients (95%) at end of treatment; persistence in 16/19 (84%) at 6 months with increasing intensity; both CD4+ and CD8+ activation; manageable injection-site AEs; no treatment-related SAEs.

Why it matters

Cancer vaccines have struggled with weak immune responses. 95% immunogenicity with persistent, intensifying responses is exceptionally promising for the field.

How the study worked

Open-label single-center phase 1 trial, 20 CLL patients receiving 3 monthly SC doses of 8 personalized peptides + XS15 adjuvant in Montanide, with IFNγ ELISpot immunogenicity and safety assessment.

What this study cannot tell us

Phase 1 without control group. CLL only. Anti-tumor clinical activity not assessed (designed for immunogenicity/safety). Small sample.

How to read the evidence

Phase 1 single-center, open-label. Exceptionally high immunogenicity rate. Anti-tumor activity assessment awaits phase 2.

When this study was published

Published in 2025, NCT04688385.

The bigger picture

The warehouse-based personalized peptide approach solves the manufacturing bottleneck of individualized cancer vaccines while maintaining near-universal immunogenicity.

Questions still open

Will the T-cell responses translate to clinical tumor regression?
Can the warehouse approach be adapted for solid tumors?
Would combining with checkpoint inhibitors enhance anti-tumor activity?

Common questions

What is a personalized peptide cancer vaccine?

It uses small protein pieces (peptides) matched to each patient's unique immune system (HLA type) and cancer. The immune system learns to recognize and attack cancer cells displaying these peptides.

Does 95% response mean it cures cancer?

Not necessarily. This trial showed the immune system responds to the vaccine in nearly all patients. Whether this immune activation translates to cancer shrinkage will be tested in larger phase 2 trials.

Read the original research

Personalised multipeptide-based T-cell activator for chronic lymphocytic leukaemia: an open-label, single-centre, phase 1 study.

The Lancet. Haematology, 13(2), e74-e85

View on PubMed ↗Publisher’s paper ↗

Citation

Heitmann, Jonas S; Maringer, Yacine; Jung, Susanne; Wacker, Marcel; Hackenbruch, Christopher; Polster, Mark; Marconato, Maddalena; Nelde, Annika; Bauer, Jens; Zwick, Melissa; Baur, Anna-Sophia; Metzger, Ariane; Krolla, Christopher; Andrieux, Geoffroy; Köhler, Natalie; Boerries, Melanie; Denk, Monika; Zieschang, Lisa; Kammer, Christine; Hoenisch-Gravel, Naomi; Richter, Marion; Oezbek, Melek Tutku; Wirths, Stefan; Dengler, Anna; Dubbelaar, Marissa L; Pumptow, Marina; Martus, Peter; Brüggemann, Monika; Rammensee, Hans-Georg; Salih, Helmut R; Walz, Juliane S. (2026). Personalised multipeptide-based T-cell activator for chronic lymphocytic leukaemia: an open-label, single-centre, phase 1 study.. The Lancet. Haematology, 13(2), e74-e85. https://doi.org/10.1016/S2352-3026(25)00323-0