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Purple Biotech Presents New IM1240 Data at EACR 2026

Purple Biotech announced the presentation of new preclinical data from its CAPTN-3 program, IM1240, at the European Association for Cancer Research, or EACR, 2026 Annual Congress, being held June 8-11, 2026, in Budapest, Hungary. IM1240 induced apoptosis of PD-1-resistant patient-derived biopsies from six HNSCC metastatic lymph node samples and one enfortumab vedotin/pembrolizumab-resistant muscle-invasive bladder cancer sample, with both the CD3 and NKG2A functional arms required for full activity. In a PD-1/chemotherapy-resistant NSCLC patient-derived explant, IM1240 induced mature tertiary lymphoid structures - immune cell organizations associated with effective anti-tumor immunity and favorable clinical prognosis - while increasing CD8 T cell and NK cell abundance and reducing regulatory T cells and tumor cells. These effects were not observed with IM1340, the NKG2A loss-of-function variant, underscoring the essential and differentiated contribution of the NKG2A arm. In a non-GLP dose-range finding toxicology study in NHPs, IM1240 demonstrated markedly superior pharmacokinetics compared to the non-capped variant IM1222, including an approximately 8-fold longer half-life and 16-fold greater systemic exposure. IM1240 showed dose-proportional PK with a broad therapeutic window, as systemic exposure associated with tumor regression in mouse models remained well below the tolerated levels in NHPs. The CAPTN-3 masking strategy effectively mitigated peripheral T-cell activation and prevented systemic cytokine release in NHPs, which is associated with one of the main safety challenges of T-cell engagers, cytokine release syndrome: IM1240 induced minimal IL-6 and TNF-a at 10 mg/kg dose, whereas the non-capped IM1222 induced robust cytokine release at just 0.03 mg/kg - a more than 300-fold difference in the dose required to trigger cytokine release. The IM1240 capping design also improved the PK profile by reducing the CD3-mediated antigen sink effect and incorporating human serum albumin to further extend half-life, as compared to the non-capped variant IM1222. IM1240 demonstrated an approximately 14-fold slower clearance than active non-capped IM1222, supporting extended exposure and potential efficacy; rapid clearance of peripherally released non-capped IM1222 reduces systemic accumulation and lowers CRS risk and off-tumor toxicity.

Purple Biotech Files $200M Mixed Securities Shelf

Purple Biotech files $200M mixed securities shelf

Purple Biotech Announces New Preclinical Data for IM1240

Purple Biotech announced new preclinical data supporting the clinical potential of IM1240, the company's lead CAPTN-3 tri-specific antibody. IM1240 is a conditionally activated, capped-CD3x5T4xNKG2A tri-specific designed to direct tumor-selective T-cell activation while also leveraging NKG2A-mediated checkpoint inhibition to enhance anti-tumor activity. The new data demonstrated potent anti-tumor activity for IM1240 across multiple treatment-resistant patient-derived tumor samples. All seven tested samples responded to IM1240 treatment, including samples from PD-1 or PD-1/chemo-resistant head and neck squamous cell carcinoma metastatic lymph nodes and enfortumab vedotin + PD-1-resistant muscle-invasive bladder cancer.