Procaspase-Activating Compound-1 Synergizes with TRAIL to Induce Apoptosis in Established Granulosa Cell Tumor Cell Line (KGN) and Explanted Patient Granulosa Cell Tumor Cells In Vitro

Abstract

Granulosa cell tumors (GCT) constitute only ~5% of ovarian neoplasms yet have significant consequences, as up to 80% of women with recurrent GCT will die of the disease. This study investigated the effectiveness of procaspase-activating compound 1 (PAC-1), an activator of procaspase-3, in treating adult GCT (AGCT) in combination with selected apoptosis-inducing agents. Sensitivity of the AGCT cell line KGN to these drugs, alone or in combination with PAC-1, was tested using a viability assay. Our results show a wide range in cytotoxic activity among the agents tested. Synergy with PAC-1 was most pronounced, both empirically and by mathematical modelling, when combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). This combination showed rapid kinetics of apoptosis induction as determined by caspase-3 activity, and strongly synergistic killing of both KGN as well as patient samples of primary and recurrent AGCT. We have demonstrated that the novel combination of two pro-apoptotic agents, TRAIL and PAC-1, significantly amplified the induction of apoptosis in AGCT cells, warranting further investigation of this combination as a potential therapy for AGCT.

Establishing combination PAC-1 and TRAIL regimens for treating ovarian cancer based on patient-specific pharmacokinetic profiles using in silico clinical trials

“…The effect of combination PAC-1 and TRAIL therapy in patients is unknown, and viable treatment schedules remain to be determined. Based on our previous in vitro study 3 , we considered weekly administrations of both drugs for 10 weeks ( Figure 4 A) to aid in the preclinical translation of combination PAC-1 and TRAIL for GCT. Accordingly, at the beginning of the i th week, we allowed for a PAC-1 dose of size 75 × Z P, i and a TRAIL dose of size 3 × BW × Z T, i to be administered (note that either or both Z P, i and Z T, i could also be equal to 0).…”

“…To model the impact of dual drug combination therapy with PAC-1 and TRAIL, we previously developed a simple system of ordinary differential equations describing the temporal evolution of ovarian cancer cells (𝐺(𝑡)) and the effects of PAC-1 (𝐶 𝑃𝐴𝐶1 ) and TRAIL (𝐶 𝑇𝑅𝐴𝐼𝐿 ) concentrations 3 . We modelled tumour cell growth to follow a Gompertzian model, which is commonly used in cancer modelling to reflect saturating growth dynamics [22][23][24][25] .…”

“…Procaspase activating compound-1 (PAC-1) is a small apoptosis activating molecule identified in a high-throughput screen of ~20,500 small-molecule compounds 4 . PAC-1 and its derivatives have since gone on to show efficacy as anti-cancer agents in vitro 3,5 and in vivo 6,7 , and have demonstrated safety in animal models [5][6][7] . PAC-1 is also under investigation in phase I trials against advanced malignancies (NCT02355535, NCT03332355), and has the potential to become a novel and effective anticancer agent 8 .…”

“…One of the main mechanisms of tumour cell killing by anti-cancer drugs is to induce programmed cell death, or apoptosis 3 . Procaspase activating compound-1 (PAC-1) is a small apoptosis activating molecule identified in a high-throughput screen of ~20,500 small-molecule compounds 4 .…”

“…To examine the efficacy of novel PAC-1 and TRAIL combination therapy while considering the impact of PK/PD heterogeneity, we extended our previous work 3 to run a virtual clinical trial of this treatment. Using our previous model describing the cell viability under treatment with PAC-1 and TRAIL, we considered the impact of heterogeneity in PK parameters on optimal combined therapeutic regimens.…”