Introduction: Glioblastoma (GBM) is the most common and lethal form of brain cancer with a median survival of only 12 months. Due to challenges associated with surgical removal, resistance to chemo- and radiotherapy, and highly invasive nature of the tumor, GBM typically recurs rapidly near the primary tumor site, and the only widely-used therapeutic agent against GBM, temozolomide (TMZ), is merely effective. Previously, we have shown that a methacrylamide-functionalized gelatin (GelMA) hydrogel platform can support addition of brain-mimetic molecules and formation of vascular networks to study GBM behavior. In this study, we assess GBM response to TMZ using a unique set of isogenically matched GBM cell lines (8MGBA-WT vs. 8MGBA-TMZres; 42MGBA-WT vs. 42MBGA-TMZres) that exhibit TMZ responsiveness (WT) or resistance (TMZres) along with disparate proliferative and invasive patterns in two-dimensional culture. This study seeks to define changes in invasion and proliferation in response to TMZ within three-dimensional gelatin hydrogels.

Methods: 8MGBA-WT, 8MGBA-TMZres, 42MGBA-WT, and 42MBGA-TMZres cell lines were cultured in DMEM with 10% FBS (100 μM TMZ continuously applied to 8MGBA-TMZres). Cells were encapsulated in GelMA hydrogels and cultured for 8 days with daily media change. After 24 hours, TMZ doses between 0 - 500 μM were applied to the gels and maintained for 7 days with daily media change. Growth rate inhibition (GR) statistics were determined after 7 days of culture. Relative cell count was assessed with the alamarBlue assay. GBM cell spheroids incapsulated in GelMA hydrogels were generated to measure relative invasion of wild type (WT) vs. TMZres lines. Spheroid outgrowth area was quantified with image analysis.

Results: We observed changes in proliferative and invasive phenotypes between the cell lines consistent with 2D cell culture. Notably, 42MGBA-TMZres cells exhibited proliferative advantage, while 8MGBA-TMZres exhibited invasive advantage. GR analysis revealed apparent differences between WT and TMZres lines with the following GR50 values: 41 μM, 8MGBA-WT; 150 μM, 8MGBA-TMZres; 77 μM, 42MGBA-WT; 339 μM, 42MGBA-TMZres. These results provide insight into potential common pathways between the “go” or “grow” phenotypes that can be used as therapeutic targets for GBM.

Conclusions: We have shown that a GelMA hydrogel platform can be used to assess GBM response to TMZ in 3D culture. This model provides insight into rapid tumor cell proliferation and diffusive local invasion. Further, this platform will be advanced to include a previously-developed model of GBM perivascular niche; this next-generation model will be used to benchmark the effect of perivascular niche on GBM therapeutic resistance and invasion. Hence, ongoing experiments aim to develop a vascularized hydrogel model of GBM to benchmark new TMZ variants hypothesized to overcome perivascular-induced resistance.

Citation Format: Viktoriia Kriuchkovskaia, Brendan A. Harley, Rebecca B. Riggins. Multidimensional hydrogel model to benchmark progression of temozolomide-resistant glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 178.