Best guess is Rubiaceae, which is unfortunately a huge family down here. It seems very familiar but I can't quite place it.
Absence of stipular scars across nodes points away from Rubiaceae. Flowers remind me slightly of genus Viburnum, but perhaps the axillary inflorescences may rule that out. Yes, there are Andean species of Viburnum, e.g. V. lasiophyllum.
