The Temozolomide–Doxorubicin paradox in Glioblastoma in vitro–in silico preclinical drug-screening

Abstract

Adjuvant Temozolomide is considered the front-line Glioblastoma chemotherapeutic treatment; yet not all patients respond. Latest trends in clinical trials usually refer to Doxorubicin; yet it can lead to severe side-effects if administered in high doses. While Glioblastoma prognosis remains poor, little is known about the combination of the two chemotherapeutics. Patient-derived spheroids were generated and treated with a range of Temozolomide/Doxorubicin concentrations either as monotherapy or in combination. Optical microscopy was used to monitor the growth pattern and cell death. Based on the monotherapy experiments, we developed a probabilistic mathematical framework in order to describe the drug-induced effect at the single-cell level and simulate drug doses in combination assuming probabilistic independence. Doxorubicin was found to be effective in doses even four orders of magnitude less than Temozolomide in monotherapy. The combination therapy doses tested in vitro were able to lead to irreversible growth inhibition at doses where monotherapy resulted in relapse. In our simulations, we assumed both drugs are anti-mitotic; Temozolomide has a growth-arrest effect, while Doxorubicin is able to cumulatively cause necrosis. Interestingly, under no mechanistic synergy assumption, the in silico predictions underestimate the in vitro results. In silico models allow the exploration of a variety of potential underlying hypotheses. The simulated-biological discrepancy at certain doses indicates a supra-additive response when both drugs are combined. Our results suggest a Temozolomide–Doxorubicin dual chemotherapeutic scheme to both disable proliferation and increase cytotoxicity against Glioblastoma.

Enhancing Therapeutic Approaches in Glioblastoma with Prooxidant Treatments and Synergistic Combinations: <em>In Vitro</em> Experience of Doxorubicin and Photodynamic Therapy

“…Nonetheless, the molecular diversity inherent in GBM and the formidable barrier presented by the blood-brain barrier (BBB) pose significant challenges in achieving complete eradication of tumor cells. Adverse prognostic outcomes in GBM patients often arise from the extensive intertumoral and intratumoral heterogeneity, as well as the occurrence of postoperative relapses and development of treatment resistance, phenomena observed in approximately half of the patients undergoing TMZ therapy [3]. Hence, there is a critical imperative to explore alternative therapeutic avenues, as conventional treatments seldom result in a cure.…”

“…Recent trends in preclinical [3,9] and clinical studies [10] of GBM have focused on the utilization of doxorubicin (DOX), one of the earliest chemotherapy agents (CTA) in cancer treatment. Doxorubicin is considered a pro-oxidant therapy due to its ability to generate ROS within cancer cells.…”