Dosages of Immunoconjugates of Antibodies and SN-38 for Improved Efficacy and Decreased Toxicity

Abstract

The present invention relates to therapeutic immunoconjugates comprising SN-38 attached to an antibody or antigen-binding antibody fragment. The antibody may bind to EGP-1 (TROP-2), CEACAM5, CEACAM6, CD74, CD19, CD20, CD22, CSAp, HLA-DR, AFP or MUC5ac and the immunoconjugate may be administered at a dosage of between 4 mg/kg and 24 mg/kg, preferably 4, 6, 8, 9, 10, 12, 16 or 18 mg/kg. When administered at specified dosages and schedules, the immunoconjugate 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.

We claim: 
     
         1 . A method of treating pancreatic cancer comprising administering to a human patient with pancreatic cancer an immunoconjugate comprising SN-38 conjugated to an hPAM4 (anti-MUC5ac) antibody or antigen-binding fragment thereof; wherein the immunoconjugate is administered at a dosage of between 3 mg/kg and 18 mg/kg, wherein the patient has failed to respond to at least one other therapy, prior to treatment with the immunoconjugate. 
     
     
         2 . The method of  claim 1 , wherein the dosage is selected from the group consisting of 3 mg/kg, 4 mg/kg, 6 mg/kg, 8 mg/kg, 9 mg/kg, 10 mg/kg, 12 mg/kg, 16 mg/kg and 18 mg/kg. 
     
     
         3 . The method of  claim 1 , wherein the treatment results in a reduction in tumor size of at least 15%, at least 20%, at least 30%, or at least 40%. 
     
     
         4 . The method of  claim 1 , wherein the cancer is metastatic. 
     
     
         5 . The method of  claim 4 , further comprising reducing in size or eliminating the metastases. 
     
     
         6 . The method of  claim 1 , wherein the cancer is refractory to other therapies but responds to the immunoconjugate. 
     
     
         7 . The method of  claim 1 , wherein the patient has failed to respond to therapy with a camptothecin, prior to treatment with the immunoconjugate. 
     
     
         8 . The method of  claim 7 , wherein the camptothecin is selected from the group consisting of irinotecan, topotecan and SN-38. 
     
     
         9 . The method of  claim 1 , wherein there is a linker between the SN-38 and the antibody. 
     
     
         10 . The method of  claim 9 , wherein the linker is CL2A and the structure of the immunoconjugate is MAb-CL2A-SN-38 
       
         
           
           
               
               
           
         
       
     
     
         11 . The method of  claim 10 , wherein the 10-hydroxy position of SN-38 in MAb-CL2A-SN-38 is a 10-O-ester or 10-O-carbonate derivative using a ‘COR’ moiety, wherein “CO” is carbonyl and the “R” group is selected from (i) an N,N-disubstituted aminoalkyl group “N(CH 3 ) 2 —(CH 2 ) n -” wherein n is 1-10 and wherein the terminal amino group is optionally in the form of a quaternary salt; (ii) an alkyl residue “CH 3 —(CH 2 ) n -” wherein n is 0-10; (iii) an alkoxy moiety “CH 3 —(CH 2 )n-O-” wherein n is 0-10; (iv) an “N(CH 3 ) 2 —(CH 2 ) n —O-” wherein n is 2-10; or (v) an “R 1 O—(CH 2 —CH 2 —O) n —CH 2 —CH 2 —O-” wherein R 1  is ethyl or methyl and n is an integer with values of 0-10. 
     
     
         12 . The method of  claim 1 , wherein there are at least 6 SN-38 molecules attached to each antibody molecule. 
     
     
         13 . The method of  claim 1 , wherein there are 6 to 8 SN-38 molecules attached to each antibody molecule. 
     
     
         14 . The method of  claim 1 , wherein the antibody is an IgG1 or IgG4 antibody. 
     
     
         15 . The method of  claim 1 , wherein the antibody has an allotype selected from the group consisting of G1m3, G1m3,1, G1m3,2, G1m3,1,2, nG1m1, nG1m1,2 and Km3 allotypes. 
     
     
         16 . The method of  claim 1 , wherein the immunoconjugate dosage is administered to the human patient once or twice a week on a schedule with a cycle selected from the group consisting of: (i) weekly; (ii) every other week; (iii) one week of therapy followed by two, three or four weeks off; (iv) two weeks of therapy followed by one, two, three or four weeks off; (v) three weeks of therapy followed by one, two, three, four or five weeks off; (vi) four weeks of therapy followed by one, two, three, four or five weeks off; (vii) five weeks of therapy followed by one, two, three, four or five weeks off; and (viii) monthly. 
     
     
         17 . The method of  claim 16 , wherein the cycle is repeated 4, 6, 8, 10, 12, 16 or 20 times. 
     
     
         18 . The method of  claim 1 , wherein the immunoconjugate is administered in combination with one or more therapeutic modalities selected from the group consisting of unconjugated antibodies, radiolabeled antibodies, drug-conjugated antibodies, toxin-conjugated antibodies, gene therapy, chemotherapy, therapeutic peptides, cytokine therapy, oligonucleotides, localized radiation therapy, surgery and interference RNA therapy. 
     
     
         19 . The method of  claim 18 , wherein the drug, toxin or chemotherapeutic agent is selected from the group consisting of 5-fluorouracil, afatinib, aplidin, azaribine, anastrozole, anthracyclines, axitinib, AVL-101, AVL-291, bendamustine, bleomycin, bortezomib, bosutinib, bryostatin-1, busulfan, calicheamycin, camptothecin, carboplatin, 10-hydroxycamptothecin, carmustine, celebrex, chlorambucil, cisplatin (CDDP), Cox-2 inhibitors, irinotecan (CPT-11), SN-38, carboplatin, cladribine, camptothecans, cyclophosphamide, crizotinib, cytarabine, dacarbazine, dasatinib, dinaciclib, docetaxel, dactinomycin, daunorubicin, doxorubicin, 2-pyrrolinodoxorubicine (2P-DOX), cyano-morpholino doxorubicin, doxorubicin glucuronide, epirubicin glucuronide, erlotinib, estramustine, epidophyllotoxin, erlotinib, entinostat, estrogen receptor binding agents, etoposide (VP16), etoposide glucuronide, etoposide phosphate, exemestane, fingolimod, flavopiridol, floxuridine (FUdR), 3′,5′-O-dioleoyl-FudR (FUdR-dO), fludarabine, flutamide, farnesyl-protein transferase inhibitors, fostamatinib, ganetespib, GDC-0834, GS-1101, gefitinib, gemcitabine, hydroxyurea, ibrutinib, idarubicin, idelalisib, ifosfamide, imatinib, L-asparaginase, lapatinib, lenolidamide, leucovorin, LFM-A13, lomustine, mechlorethamine, melphalan, mercaptopurine, 6-mercaptopurine, methotrexate, mitoxantrone, mithramycin, mitomycin, mitotane, navelbine, neratinib, nilotinib, nitrosurea, olaparib, plicomycin, procarbazine, paclitaxel, PCI-32765, pentostatin, PSI-341, raloxifene, semustine, sorafenib, streptozocin, SU11248, sunitinib, tamoxifen, temazolomide (an aqueous form of DTIC), transplatinum, thalidomide, thioguanine, thiotepa, teniposide, topotecan, uracil mustard, vatalanib, vinorelbine, vinblastine, vincristine, vinca alkaloids and ZD1839.