The present invention relates to combination therapy with drugs, such as Brutons tyrosine kinase inhibitors or PI3K inhibitors, with antibodies or ADCs against HLA-DR. Where ADCs are used, they preferably incorporate SN-38 or pro-2PDOX. The ADC may be administered at a dosage of between 1 mg/kg and 18 mg/kg, preferably 4, 6, 8, 9, 10, 12, 16 or 18 mg/kg. The combination therapy can reduce solid tumors in size, reduce or eliminate metastases and is effective to treat cancers resistant to standard therapies, such as radiation therapy, chemotherapy or immunotherapy. Preferably, the combination therapy has an additive effect on inhibiting tumor growth. Most preferably, the combination therapy has a synergistic effect on inhibiting tumor growth.
