Assessment of the therapeutic effect of IGS2.7, a CK1δ protein kinase inhibitor, in combination with riluzole for the treatment of ALS-associated TDP-43 proteinopathy.

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease for which no effective treatments currently exist. The FDA and EMA have approved only riluzole, a drug that modestly extends patient survival by 3-18 months. In our research, we have identified a novel CK1δ inhibitor, IGS2.7, which modulates TDP-43 proteinopathy, the main ALS pathological hallmark, in both patient-derived cellular models and TgTDP-43 mice. To assess the potential of IGS2.7 as a therapeutic candidate and considering riluzole remains the standard care for ALS patients, we evaluated its effects in combination with riluzole. Our results demonstrate that co-administration of IGS2.7 and riluzole at effective doses does not cause adverse effects. However, no additional therapeutic benefit was observed beyond that of IGS2.7 monotherapy, suggesting that IGS2.7 may be viable as either a stand-alone treatment or as an adjunct to riluzole. Notably, when suboptimal doses of both drugs were administered, a combined effect was observed. This suggests that, once IGS2.7 reaches clinical testing, its use together with lower doses of riluzole may enhance therapeutic efficacy while potentially minimizing side effects. Additional in vivo pre-clinical studies will be required to further evaluate this possibility, although only clinical trials will ultimately determine its clinical relevance.