Of the 6 pts in the roll-over cohort, 3 pts with RSPO3 fusion tumors achieved PR during CGX1321 + pembro combination therapy....CGX1321 has demonstrated potent inhibition of the WNT pathway with manageable side effects. Promising efficacy signals have been observed in pts whose tumors harbor RSPO fusion, supporting further development of CGX1321 monotherapy and CGX1321 + anti-PD-1/L1 in a defined patient population that is historically known to be refractory to standard therapies and immune checkpoint inhibitors.