Kura Oncology tumbles on 'credible threat' from J&J's rival blood cancer therapy

** Shares of Kura Oncology KURA.O fall 18% to $8.10 in afternoon trading, after Johnson & Johnson's JNJ.N ASH abstract raises competitive pressure

** Kura stock to notch its steepest one-day percentage decline in nearly two years, if losses hold

** J&J's bleximenib, seen as a "stronger-than-anticipated competitor" and a "credible threat" to Kura's Komzifti in relapsed/refractory acute myeloid leukemia (AML), Leerink Partners analysts say

** Komzifti won FDA approval last year to treat relapsed/refractory NPM1-mutant AML, an aggressive cancer of the blood and bone marrow

** Cantor analysts view competitor data as a "modest negative for the R/R AML commercialization," but believes Kura remains "competitively positioned" in frontline

** As of last close, KURA down 21.7% YTD