from the ASCO Annual Meeting 2026.

The abstract is shown below and the poster being presented today can be seen and downloaded at the bottom of the Phase III clinical trial tab on the Company's website here.

  • This is the second abstract and poster presented jointly with the Steering Committee of FLAMINGO-01 with statistically significant injection site reaction (ISR) immune response data, with subgroup analysis by the most prevalent HLA types.
  • In the non-HLA-A*02 open label arm where all patients (n=247) were treated with GLSI-100, immune responses to GP2 were measured at baseline and over time using skin tests (DTH) and ISRs.
  • An ISR reaction, erythema (redness) or induration (white hard bump), was used to assess in vivo immune responses in patients. The diameter of the reaction was assessed 48-72 hours after injection but is not reported here.
  • In this preliminary data analysis, there was a significant increase in percentage of patients experiencing an ISR reaction (for both erythema and induration) in vaccination 4, vaccination 5 or vaccination 6 compared to the baseline vaccination. There were 208 patients with both baseline vaccination and vaccination 4, 5 or 6 assessments.
  • Erythema: There was a significant increase in the percentage of patients experiencing erythema ISRs after the 4th, 5th or 6th vaccination compared to the ISRs from the 1st vaccination. In this preliminary analysis, the frequency of ISRs increased significantly from 20.2% of the patients experiencing an ISR after the first vaccination to 55.3% of the patients experiencing an ISR after the 4th, 5th or 6th vaccination (McNemar p < 0.001), representing an increase of 2.7x or 174%.
  • Induration: There was a significant increase in the percentage of patients experiencing induration ISRs after the 4th, 5th or 6th vaccination compared to the ISRs from the 1st vaccination. In this preliminary analysis, the frequency of ISRs increased significantly from 14.9% of the patients experiencing an ISR after the first vaccination to 34.6% of the patients experiencing an ISR after the 4th, 5th or 6th vaccination (McNemar p < 0.001), representing an increase of 2.3x or 132%.
  • As reported in Table 1, each HLA-A type exhibited more frequent immune reactivity with increased GLSI-100 vaccinations with frequency increasing by 60% to 280% over the frequency after the first vaccination. These results are consistent with the GP2 DTH results presented at AACR.
  • Mechanism of Action: A positive immune response is an indicator that the immune system has been activated against recurring cancer cells, potentially leading to the prevention of metastatic breast cancer. The Company previously announced that in the non-HLA-A*02 arm, a preliminary analysis of recurrence rates after the Primary Immunization Series (PIS) is completed shows an approximately 70-80% reduction in recurrence rate. Thus, the immune response data is supporting the mechanism of action that reduces recurrences and prevents metastatic breast cancer.
  • This statistically significant non-HLA-A*02 open label arm immune response data for both DTH and ISRs is trending similarly to the immune response data in the HLA-A*02 patients in the Phase IIb study and the HLA-A*02 arms of FLAMINGO-01. The study is ongoing and data collection and cleaning continue, while some patients may still be in their PIS vaccination phase, so final results may vary.



     

The immune response abstract and poster conclusion: The statistically significant increase in the incidence of ISR reactions over time found in this preliminary analysis of GLSI-100 treated non-HLA-A*02 patients shows that GLSI-100 treatment should not be limited to HLA-A*02 patients. Patients treated with GLSI-100 were increasingly able to mount an immune response to GP2 as evidenced in this preliminary data. Future investigations may explore the use of immune responses to assess correlation of DTH to ISRs, immunogenicity of GLSI-100 by specific HLA type, timing of boosters to sustain immunity, clinical site performance, and the discontinuation of treatment for non-responders.

CEO Snehal Patel commented, "The DTH immune response data presented at AACR and the ISR immune response data presented today together further support the mechanism of action and the combination of HLA-A*02 and non-HLA-A*02 patients in the same randomized arms, potentially improving the chances of success at the interim analysis and more than doubling the market potential for GLSI-100. This combination of patients, independent of HLA type, has already started in the US and may soon start in Europe. In addition to ASCO, the Company previously attended AACR and ESMO Breast and plans to attend BIO partnering and investor conferences in the coming months, while presenting additional FLAMINGO-01 data at any time."