(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization I International Bureau (10) International Publication Number (43) International Publication Date WO 2013/093809 Al 27 June 2013 (27.06.2013) P O P C T (51) International Patent Classification: TUMEY, Nathan; 37 William Street, Pawcatuck, Con C07K 16/00 (2006.01) C07K 16/30 (2006.01) necticut 06379 (US). (21) International Application Number: (74) Agent: KLEIMAN, Gabriel L.; Pfizer Inc., 235 East 42nd PCT/IB2012/057491 Street, New York, New York 10017 (US). (22) International Filing Date: (81) Designated States (unless otherwise indicated, for every 19 December 2012 (19. 12.2012) kind of national protection available): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, English (25) Filing Language: BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, (26) Publication Language: English DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, (30) Priority Data: KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, 61/580,169 23 December 201 1 (23. 12.201 1) US ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, (71) Applicant: PFIZER INC. [US/US]; 235 East 42nd Street, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, New York, New York 10017 (US). RW, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, (72) Inventors: MARQUETTE, Kimberly; 66 Springfield ZM, ZW. Street, Apt. #1, Somerville, Massachusetts 02143 (US). BENNETT, Eric; 45 Morningside Drive, Arlington, Mas (84) Designated States (unless otherwise indicated, for every sachusetts 02474 (US). TCHISTIAKOVA, Lioudmila; 19 kind of regional protection available): ARIPO (BW, GH, Abbot Bridge Drive, Andover, Massachusetts 01810 (US). GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, [Continued on nextpage] (54) Title: ENGINEERED ANTIBODY CONSTANT REGIONS FOR SITE-SPECIFIC CONJUGATION AND METHODS AND USES THEREFOR (57) Abstract: The present invention is directed to anti bodies, and antigen-binding portions thereof, engin Figure 11 eered to introduce amino acids for site-specific conjug ation. The invention relates to engineered antibody con stant region (Fc, Cy, CK, and CX) polypeptides, and portions thereof, and antibodies comprising the poly 5T4 Engineered Antibody Binding in MDAMB435/5T4 Cell □ 1ug/ml peptides. Further, the invention relates to Fc fusion pro ■ 10ug/ml teins comprising an engineered Fc region. The inven tion also relates to methods and uses of the engineered antibodies and portions for, among other things, pro duction of antibody-drug conjugate therapeutics. © 00 © o o w o 2013/093809 Ai III 111 II II III I I11 III III II IIII 11ll ll III II I II TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, — as to the applicant's entitlement to claim the priority of EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, the earlier application (Rule 4.1 ?'(in)) LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, Published: GW, ML, MR, NE, SN, TD, TG). — with international search report (Art. 21(3)) Declarations under Rule 4.17: — before the expiration of the time limit for amending the — as to the identity of the inventor (Rule 4. 7(i)) claims and to be republished in the event of receipt of amendments (Rule 48.2(h)) — as to applicant's entitlement to apply for and be granted patent (Rule 4.1 7(H)) — with sequence listing part of description (Rule 5.2(a)) ENGINEERED ANTIBODY CONSTANT REGIONS FOR SITE-SPECIFIC CONJUGATION AND METHODS AND USES THEREFOR REFERENCE TO SEQUENCE LISTING This application is being filed electronically via EFS-Web and includes an electronically submitted sequence listing in .txt format. The .txt file contains a sequence listing entitled "PC07 1868A_Sequence_Listing.txt" created on December 15 , 201 2 , and having a size of 303 KB. The sequence listing contained in this .txt file is part of the specification and is incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates to antibodies, and fragments thereof, wherein at least one constant region is engineered to introduce an amino acid for site-specific conjugation . The invention further relates to methods and uses of the engineered antibodides and fragments for, among other things, production of antibody-drug conjugate therapeutics. BACKGROUND OF THE INVENTION More than 1.2 million Americans develop cancer each year. Cancer is the second leading cause of death in the United States with one in two men and one in three women diagnosed with cancer at some time during their lifetime. Although many chemotherapeutic agents have been developed, they often demonstrate unacceptable toxicity and or lack of specificity for cancer cells over non-cancer tissues. To avoid the non-specific cytotoxic effects of chemotherapeutic agents, targeted antibody therapy has revolutionized cancer treatment, with several monoclonal antibodies (mAbs) demonstrating clinical potential. Because antibodies against tumor-specific antigens often lack therapeutic activities, they have been conjugated to cytotoxic agents in order to combine the effectiveness of chemotherapy with the targeting of antibodies. In principle, selective delivery of cytotoxic agents to specific tumor issues by antibody binding should reduce the systemic toxicity of traditional small-molecule chemotherapeutics. Antibodies have been conjugated to a variety of cytotoxic drugs, including small molecules that alkylate DNA (e.g. , duocarmycin and calicheamicin), disrupt microtubules (e.g. , maytansinoids and auristatins) or bind DNA (e.g. , anthracyclins). One such antibody-drug conjugate (ADC) comprising a humanized anti-CD33 antibody conjugated to calicheamicin - Mylotarg ™ (gemtuzumab ozogamicin, Wyeth) - was approved in 2000 for acute myeloid leukemia. More recently, the US Food and Drug Administration approved Adcetris™ (brentuximab vedotin; Seattle Genetics), an ADC comprising a chimeric antibody to CD30 conjugated to the auristatin monomethyl auristatin E (MMAE; also referred to as N-methylvaline-valine-dolaisoleuine-dolaproine-norephedrine) for treatment of Hodgkin's lymphoma and anaplastic large cell lymphoma. Although ADCs hold promise for cancer therapy, cytotoxic drugs are generally conjugated to the antibodides via lysine side chains or by reducing interchain disulfide bonds present in the antibodies to provide activated cysteine sulfhydryl groups. This non-specific conjugation approach, however, has numerous drawbacks. Not only is it capable of affecting protein folding by disrupting cystine bonds, non-specific conjugation creates a heterogeneous mixture of antibodies having a diverse mix of antibody-to-drug ratios (ADR) and also having a complex mixture of antibodies conjugated at a variety of positions. So, even if it was somehow possible to purify sufficient antibodies having a desired antibody:drug ratio, the fraction would still comprise a complex mix of antibodies conjugated at various positions. Each species could potentially have distinct therapeutic properties, and batch-to-batch consistency would be difficult to control, all of which present significant hurdles to success of using ADC for cancer therapy. To attempt to avoid the drawbacks of non-specific conjugation , a number of approaches have been proposed to provide site-specific conjugation of drug to antibody. However, previous studies attempting to provide reactive conjugation sites in antibodies have shown that biotin or other small non-toxic molecules conjugated to engineered cysteines at other positions of human lgG1 did not appear to affect antibody binding to certain antigens. See, e.g. , WO 201 1/005481 (biotin-maleimide conjugation); WO 201 0/1 4 1902 (conjugating cysteine variants with maleimide dyes); and WO 2006/034488 (biotin-maleimide conjugation was performed and all examples describing conjugation to monomethyl auristatin E (MMAE; N-methylvaline-valine-dolaisoleucine-dolaproine-norephedrine) and monomethyl auristatin F (MMAF; also referred to as "N-methylvaline-valine-dolaisoleuine-dolaproine- phenylalanine") were prophetic only). However, conjugation of a small non-toxic molecule such as biotin as was typically used in those studies is unlikely to mimic the impact on the biological properties an antibody molecule comprising a linker and cytotoxic molecule. Because a successful ADC platform antibody must successfully bind to a target antigen in order to deliver a toxic payload to a target cell without significant binding to non-target cells, it is crucial that the engineered mutant antibodies of the invention retain specific binding ability whilst conjugated to a toxic payload. It is also crucial that the ADC be able to deliver a toxic payload to a target cell, be internalized thereby, and then release the payload once inside the appropriate compartment within the cell. Each of these necessary characteristics for a successful ADC was not demonstrated by prior studies. Despite the successes of currently available anti-cancer treatments, complete responses to these treatments or prolonged survival are infrequently observed, and the patient population refractory to these treatments is still large. Thus, there is an unmet need for the development of new therapeutic modalities, particularly those capable of augmenting or potentiating the anti-tumor activity of anti-neoplastic agents while reducing the cytotoxic