This invention relates to new crystalline forms of (10R)-7-amino-12-fluoro-2,10,16-trimethyl-15-oxo-10,15,16,17-tetrahydro-2H-8,4-(metheno)pyrazolo[4,3-h][2,5,11]benzoxadiazacyclotetradecine-3-carbonitrile(lorlatinib) maleate. The invention also relates to pharmaceutical compositions comprising lorlatinib maleate, and to methods of using lorlatinib maleate and compositions comprising it in the treatment of abnormal cell growth, such as cancer, in mammals.