4-((S)-8-(3-(((S)-2-(4-((S)-2-((S)-2-amino-3-methylbutanamido)propanamido)phenyl)-7-methoxy-5-oxo-5,11a-dihydro-1H-benzo[e]pyrrolo[1,2-a][1,4]diazepin-8-yl)oxy)propoxy)-7-methoxy-5-oxo-5,11a-dihydro-1H-benzo[e]pyrrolo[1,2-a][1,4]diazepin-2-yl)benzoic acid