AltruBio reports Phase 2a ALTB-268 results in ulcerative colitis, with preliminary Week 12 remission findings ahead of a planned placebo-controlled Phase 2b trial.
Written By: Malavatu Satvika, PharmD
Reviewed By: Pharmacally Editorial Team
On October 20, 2026, AltruBio reported Phase 2a findings for ALTB-268 from the ASCEND UC2a study (NCT06109441), evaluating adults with moderately to severely active UC who had an inadequate response to prior advanced therapies. The results showed preliminary clinical activity, although the study design does not establish benefit over placebo.
Ulcerative colitis (UC) is a chronic inflammatory bowel disease that can cause intestinal inflammation, diarrhoea and rectal bleeding. Patients who do not respond adequately to advanced therapies have limited treatment options, creating a need for new approaches to disease management.
Trial Design and Endpoints
ASCEND UC2a was an open-label, sequential dose-exploration study. A total of 48 participants received subcutaneous ALTB-268 during a 12-week induction period. Cohort 1 included 35 participants receiving the lower dose, while Cohort 2 included 13 receiving a dose twice as high.
The study assessed clinical remission, clinical response, endoscopic improvement, patient-reported quality of life measured using the Inflammatory Bowel Disease Questionnaire (IBDQ), safety and pharmacokinetics.
Because the cohorts were enrolled sequentially rather than randomized concurrently, differences between them cannot confidently be attributed to dose alone. The absence of a placebo group also limits assessment of treatment effect.
Week 12 Efficacy Findings
Clinical remission occurred in 4/35 participants (11.4%) in the lower-dose cohort and 3/13 (23.1%) in the higher-dose cohort. Clinical response was reported in 12/35 (34.3%) and 7/13 (53.8%), respectively.
Endoscopic improvement occurred in 6/35 participants (17.1%) in Cohort 1 and 3/13 (23.1%) in Cohort 2. IBDQ response was similar between groups, at 18/35 (51.4%) and 7/13 (53.8%), respectively.
The higher-dose cohort therefore showed numerically higher remission, clinical response and endoscopic improvement rates, while patient-reported quality-of-life response was broadly similar. However, remission represented only four participants in the lower-dose cohort and three in the higher-dose cohort. In groups this small, a few individual outcomes can substantially affect reported percentages.
These findings support further investigation but do not establish dose superiority or statistical significance. Clinical response, remission, endoscopic improvement and IBDQ response measure different aspects of disease activity and patient experience. Endoscopic improvement should not be interpreted as complete mucosal healing without supporting data.
Exposure-Response Findings and Mechanism
An exploratory analysis examined 18 participants whose Day 29 trough drug concentration met or exceeded a predefined target. At Week 12, 7/18 (38.9%) achieved clinical remission and 7/18 (38.9%) achieved endoscopic improvement. Clinical response and IBDQ response were each reported in 10/18 participants (55.6%).
Preliminary modelling suggested a positive relationship between Day 29 trough concentration and clinical remission. This association may help inform dose selection, but it does not demonstrate causation or validate the target concentration as a therapeutic threshold. Because the subgroup was defined by drug exposure after treatment began, its outcomes may also reflect patient characteristics or differences in drug handling. These results should not be generalized to all treated participants.
ALTB-268 is a subcutaneous tetravalent agonist antibody targeting PSGL-1 (CD162). AltruBio proposes that it downregulates chronically activated, late-stage effector T cells through exhaustion and/or apoptosis. This proposed mechanism provides a rationale for immune modulation, but the Phase 2a findings do not independently establish the mechanism’s contribution to clinical outcomes.
Safety and Next Steps
AltruBio reported similar overall proportions of treatment-emergent adverse events across the two cohorts despite the two-fold dose difference. Injection-site reactions were the most common events, decreased with repeat administration and were not observed in either cohort by the end of induction. One serious adverse event occurred in Cohort 1, and no deaths were reported.
Although these findings provide an initial view of tolerability, 48 participants followed over a 12-week induction period are insufficient to characterize uncommon adverse events or long-term safety.
AltruBio is preparing the global, placebo-controlled Phase 2b ASCEND UC2b study, which is expected to begin in 2027. The trial will evaluate two active doses and assess clinical remission during induction and response durability during maintenance. The company has also indicated plans to study both advanced therapy-experienced and advanced therapy-naïve patients.
Clinical Interpretation
ASCEND UC2a provides preliminary evidence of clinical activity for ALTB-268 in moderately to severely active UC. Numerically higher remission and clinical response rates in the higher-dose cohort, together with the exploratory exposure-response signal, support further evaluation. However, the sequential open-label design, small cohorts and lack of a placebo comparator prevent firm conclusions about efficacy or dose superiority.
The planned Phase 2b study will be important in determining whether these early findings translate into a reproducible treatment benefit and whether responses can be sustained during maintenance. Until randomized comparative data become available, ALTB-268 remains investigational and cannot be considered an established alternative to approved UC therapies.
References
AltruBio. AltruBio Presents Phase 2a Data of ALTB-268 in Advanced Therapy-Refractory Ulcerative Colitis at UEG Week 2026. October 20, 2026.
Efficacy/Safety of ALTB-268 in Subjects w/Moderately to Severely Active UC Refractory to Biologics, ClinicalTrials.gov ID NCT06109441
About the Writer
Malavatu Satvika (Linkedin) is a Pharm.D professional and aspiring healthcare medical writer with clinical exposure and research experience. Her interests include medical writing, drug safety, pharmaceutical research, and evidence-based healthcare communication. She has contributed to two research publications in pharmaceutical journals and has gained practical experience in prescription review, patient counselling, medication review, adverse drug reaction monitoring, drug information services, literature review, and clinical documentation through regular hospital training.
She has completed certifications in clinical research, ICH-GCP E6(R3), data management for clinical research, and congenital hypothyroidism. With a strong foundation in pharmacy, clinical practice, and scientific research, she aims to translate complex medical and pharmaceutical information into accurate, clear, and evidence-based healthcare content. She is also preparing to pursue a PhD and further develop her expertise in medical writing and pharmaceutical research.