Solid forms comprising 3-(5-amino-2-methyl-4-oxo-4H-quinazolin-3-yl)- piperidine-2,6-dione, compositions comprising the solid forms, methods of making the solid forms and methods of their uses are disclosed.Linvention concerne des formes solides comprenant un 3-(5-amino-2-méthyl-4-oxo-4H-quinazolin-3-yl)- pipéridine-2,6-dione, des compositions comprenant les formes solides, des procédés de production de ces formes solides et leurs méthodes dutilisation.