Updated data from the poster were provided in a press release on June 3rd which extended the observation period for the patients an extra 30 days.
One patient remains progression free at 34.9 months. Overall survival (OS) was not calculated as five of thirteen remain alive and measurements are ongoing. Safety appears to be good with no cell therapy related toxicities such as immune effector cell-associated neurotoxicity syndrome or cytokine release syndrome reported in patients receiving up to the maximum dose of six infusions of the therapy.
Standard of care (SoC) for newly diagnosed GBM requires primary resection, six weeks of daily chemoradiation therapy followed by six cycles of monthly maintenance temozolomide therapy (Stupp regimen). SoC produces a median PFS of 7 months and an overall survival (OS) of approximately 14 to 16 months as reported by IN8bio.
Our own review finds a range of reported survival of nine months to the upper twenty-month range depending upon specific characteristics. Most of the more recent resources we reviewed were 15 months or less. Factors associated with differing survival rates include age, further tumor treatment after surgery and MGMT promoter methylation among other contributors.1,2,3,4,5,6
Key Findings
All patients who completed the protocol mandated doses surpassed the median PFS of seven months with a majority also exceeding expected PFS based on age and O?-methylguanine-DNA methyltransferase (MGMT) status. 92% exceeded mPFS of seven months. The most common treatment-emergent adverse events were Grade 1 or 2 toxicities consisting of white blood cell and platelet count decreases related to temozolomide.
? Radiographic evaluation pre- and post-treatment included resolution of midline shift in one patient with evidence of changes in enhancement attributed to treatment effect in multiple patients;
? One subject was found to have a 36% decrease in a lesion attributed to positive treatment effect;
? Preserved γδ T cells were found in relapsed tumors 148 days after initial drug resistant immunotherapy (DRI) infusion in one patient with paired biopsies, pointing to durability of DRI γδ T cells.
In this first study evaluating the use of γδ T cells in GBM, there has been promising data so far that exceeds SoC thresholds for PFS. γδ T cells have shown that they are safe with limited negative side effects and strong synergies with temozolomide which functions as an effective lymphodepleting regimen for use with cellular therapy. The DRI feature of IN8bio’s modified γδ T cells allows the therapy to thrive in the tumor environment, immune from the effects of temozolomide and alerted to the cancer cells which are more visible to γδ T cell therapy when exposed to temozolomide. Early data from the INB-200 study shows that repeat doses result in longer time to progression. Positive results from the trial so far support further study. A follow-on trial for candidate INB-400 will take the baton from INB-200 and evaluate a larger group of patients.
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1. Brown, N.F. et al. Survival Outcomes and Prognostic Factors in Glioblastoma. Cancers. July 2022. (9.2 months)
2. Hertler, C. et al. Long-term survival with IDH wildtype glioblastoma: first results from the ETERNITY Brain Tumor Funders’ Collaborative Consortium. European Journal of Cancer, 2023 (9.9 months)
3. Bjorland, L.S. et al. Treatment approach and survival from glioblastoma: results from a population-based retrospective cohort study from Western Norway. Oncology, 2021. (10.2 months)
4. Stupp R. et al. Radiotherapy plus concomitant and adjuvant Temozolomide for glioblastoma. N Engl J Med. 2005. (14.6 months)
5. Chang, K. et al. Multimodal imaging patterns predict survival in recurrent glioblastoma patients treated with bevacizumab. Neuro-Oncology. 2016. (15 months)
6. Alafandi, A. et al. Association of pre-radiotherapy tumour burden and overall survival in newly diagnosed glioblastoma adjusted for MGMT promoter methylation status. European Journal of Cancer. 2023. (27 methylated & 14 unmethylated).
