WEE1/PKMYT1 Dual Targeting in CIC::DUX4 Sarcoma
| CIC::DUX4 sarcoma is an aggressive and ultra-rare cancer affecting children, adolescents, and young adults (AYA), characterized by poor clinical outcomes and limited effective treatment options. These tumors grow rapidly and frequently metastasize, highlighting an urgent need for biologically targeted therapies. The CIC::DUX4 fusion oncoprotein drives uncontrolled proliferation and elevated replication stress, a condition in which cancer cells accumulate DNA damage during cell division. To survive this stress, tumor cells rely on the G2/M checkpoint, a protective regulatory pathway that delays mitosis and permits DNA repair. This checkpoint is regulated by two complementary kinases, WEE1 and PKMYT1, which together inhibit CDK1 and control cell cycle progression. We hypothesize that simultaneous inhibition of WEE1 and PKMYT1 will abrogate this checkpoint, prevent repair of replication-associated damage, and induce tumor cell death. To test this hypothesis, we will evaluate the clinically advanced WEE1 inhibitor ZN-c3 and the PKMYT1 inhibitor Lunresertib, alone and in combination, in patient-derived CIC::DUX4 sarcoma models. Therapeutic efficacy will be assessed using quantitative cell-viability and drug-synergy analyses. Mechanistic studies will measure replication stress and DNA damage (pRPA32, ?H2AX), checkpoint disruption (phospho-CDK1), and apoptosis (cleaved PARP) to confirm that dual checkpoint inhibition induces premature and lethal mitotic entry. In vivo xenograft studies will further evaluate tumor growth suppression and treatment tolerability. To our knowledge, this is the first study to investigate combined WEE1 and PKMYT1 inhibition in CIC::DUX4 sarcoma. This work represents a mechanism-based therapeutic strategy targeting G2/M checkpoint dependence in this disease. Because both agents are already in clinical development, these studies establish a strong translational foundation for advancing a rational therapeutic strategy for patients with this high-risk disease. |