This concept has been proposed as a therapeutic approach to kill cancer cells harboring genes that are sensitive to complete loss of expression, referred to as CYCLOPS genes.[23] HSPA9 is reduced by 50% in del(5q)-associated MDS cells, consistent with haploinsufficient levels.[4] We tested whether MDS samples with del(5q) spanning the HSPA9 gene maybe more sensitive to further HSPA9 reduction than MDS samples without del(5q) using MKT-077. The gene discussed is HSPA9; the disease is myelodysplastic syndrome.