Doxorubicin-Immunoconjugate Therapy of Non-Hodgkin's Lymphoma

描述（由申请人提供）：单克隆抗体（mab）与药物或毒素的偶联物作为一种更特异性地将这些药物递送到癌症的潜在方法已经研究了多年。其中一种化合物Mylotarg（）是抗cd33抗体与强效细胞毒药物calicheamicin的结合物，已获得FDA批准用于治疗60岁以上首次复发的cd33阳性急性髓性白血病患者。其他药物- mab偶联物目前正在开发中，用于治疗各种实体肿瘤。尽管一些人认为传统抗癌药物（如阿霉素（Dox））的单抗偶联物没有足够的效价来产生显著的治疗效果，但我们已经积累了大量证据表明，正确的抗原-抗体靶向系统可以产生高效的Dox-免疫偶联物。CD74是一种与HLA-DR结合的ⅱ型跨膜伴侣分子，可抑制抗原肽与ⅱ类抗原呈递结构的结合。它在几种类型的肿瘤细胞（如NHL、MM、黑色素瘤和RCC细胞）表面表达，并指导从表面转运到细胞内的内体腔室。我们已经证明了放射性核素抗体偶联物对CD74+ B细胞的有效活性，使用快速内化的LL1抗体靶向带有俄格电子发射体标记的CD74。这些结果为测试LL1-anti-CD74 MAb的给药作用提供了动力。阿霉素是治疗非霍奇金淋巴瘤的一种关键药物，它在药物偶联治疗中具有许多优点，包括：(a)水溶性，因此很容易与蛋白质水溶液相容；(b)具有几个化学反应基团的；(c)具有多种作用机制，包括抑制拓扑异构酶II、嵌入DNA和破坏细胞膜。LL1-Dox在系统性NHL异种移植模型中的治疗效果非常突出（见初步结果和附加的手稿）。非霍奇金淋巴瘤（NHL）是美国第五大常见癌症，每年占所有癌症相关死亡人数的5%。5年治愈率仅为50%。已知这些肿瘤表达大量的CD74抗原。NHL可能对使用药物- ab缀合物的特定靶向方法有最好的反应，因为其广泛播散的性质和癌细胞对系统给药的相对可及性。此外，造血肿瘤具有更高的固有敏感性，这种疾病的自然过程是细胞生长失控，最终数量超过正常B细胞，与正常细胞相比，这提供了将更高比例的注射药物ab特异性递送到病变细胞的机会。因此，该提案将利用几种已建立的临床前模型和原发性NHL活检标本，解决LL1-Dox免疫偶联物治疗弥散性NHL的效用。我们还将解决几个新的生物学问题，包括(a)通过直接将阿霉素与抗体一起递送来克服多药耐药（通常由~60%的难治NHL患者表达）的可能性，以及(b)克服与游离阿霉素管理相关的心脏毒性。

DESCRIPTION (provided by applicant): Conjugates of monoclonal antibodies (MAbs) with drugs or toxins have been investigated for many years as a potential approach to delivering these agents more specifically to cancers. One such compound, Mylotarg(, a conjugate of the anti-CD33 antibody with the highly potent cytotoxic drug, calicheamicin, has gained FDA approval for treatment of CD33-positive acute myeloid leukemia in patients over age 60 in first relapse. Other drug-MAb conjugates are currently in development for the treatment of various solid tumors. Although some have suggested that Mab conjugates of conventional anticancer drugs, such as doxorubicin (Dox) would not have adequate potency to elicit a significant therapeutic effect, we have accumulated a large body of evidence showing that the correct antigen-antibody targeting system can result in a highly effective Dox-immunoconjugate. CD74 is a type-ll transmembrane chaperone molecule that associates with HLA-DR, inhibiting binding of antigenic peptides to the class-ll antigen presentation structure. It is expressed on the surface of several types of tumor cells (e.g., NHL, MM, melanoma and RCC cells) and directs transport from the surface to an endosomal compartment within the cell. We have shown potent activity of antibody conjugates of radionuclides against CD74+ B cells, using the rapidly internalizing LL1 antibody to target CD74 labeled with Auger electron emitters. These results provided the impetus to test the LL1-anti-CD74 MAb for drug delivery. Doxorubicin, a key drug in the management of NHL affords many advantages for drug-conjugate therapy including: (a) water-soluble nature and therefore readily compatible with aqueous protein solutions; (b) having several chemically reactive groups; (c) possessing several mechanisms of action, including inhibition of topoisomerase II, intercalation into DNA, and disrupting on cell membranes. Therapeutic results with LL1-Dox in a systemic NHL xenograft model have been outstanding (see preliminary results and appended manuscript). Non-Hodgkin's lymphoma (NHL) is the 5th most common cancer in the U.S. and accounts for 5% of all cancer-related deaths per year. The 5-year cure rate is only 50%. These tumors are known to express significant amounts of the CD74 antigen. NHL might best respond to a specific targeting approach using a drug-Ab conjugate, due to its widely disseminated nature and the relative accessibility of cancer cells to systemically administered agents. In addition, the greater inherent sensitivity of hematopoietic tumors, the natural course of this disease with cells growing out of control and terminally outnumbering normal B cells, offers the chance of delivering a much higher ratio of injected drug-AB specifically to diseased cells, as compared to normal cells. This proposal will therefore address the utility of an LL1-Dox immunoconjugate for treatment of disseminated NHL using several established preclinical models and primary NHL biopsy specimens. We will also address several novel biological questions including (a) the possibility of overcoming multidrug resistance (typically expressed by ~60% of refractory NHL patients) by delivering Dox directly with an antibody, and (b) overcoming cardiotoxicity associated with the administration of free doxorubicin.