Best overall response: CR+PR 0%; SD 61% (11/18); PD 28% (5/18); unevaluable 11% (2/18)....At a median follow-up of 7.9 months, median PFS was 3.2 months (95% CI, 1.8-3.9)....NOTCH1 was the most frequent alteration (4, 22%) with 2 evaluable NOTCH1-mutant patients exhibiting SD...Low MYB protein expression was associated with longer duration of stability (p<0.01)....SD was observed among R/M ACC patients with disease progression 12 months prior to enrollment. This combined with limited toxicity makes ATRA a treatment option for long-term growth stabilization...