Provided herein are pharmaceutical compositions comprising a phosphatidylinositol 3-kinase inhibitor, or pharmaceutically acceptable form thereof, in combination with a second agent, or a pharmaceutically acceptable form thereof, wherein the second agent is chosen from one or more of 1) a checkpoint modulator, 2) an XPO1 inhibitor, 3) an anti-CD19 antibody, 4) a TLR agonist, 5) a STING agonist, or 6) a Flt3 ligand, or a combination thereof. Also provided herein are methods of treatment comprising administration of the compositions, and uses of the compositions, e.g., for treatment of cancer.