Doxorubicin-Immunoconjugate Therapy of Non-Hodgkin's Lymphoma

描述(由申请人提供)：多年来，人们一直在研究单抗(MAb)与药物或毒素的结合，以此作为一种潜在的方法来将这些药物更特异地输送到癌症中。其中一种化合物Mylotarg(是抗CD33抗体与高效细胞毒性药物Calicheamicin的结合物)已获得FDA批准，用于治疗首次复发的60岁以上患者的CD33阳性急性髓系白血病。其他药物-单抗结合物目前正在开发中，用于治疗各种实体肿瘤。虽然有些人认为传统抗癌药物的单抗结合物，如阿霉素(Dox)，不足以产生显著的治疗效果，但我们积累了大量的证据表明，正确的抗原-抗体靶向系统可以产生高效的Dox-免疫结合物。CD74是一种与人类白细胞抗原-DR相关的II型跨膜伴侣分子，抑制抗原肽与第II类抗原提呈结构的结合。它在几种类型的肿瘤细胞(如非霍奇金淋巴瘤、多发性骨髓瘤、黑色素瘤和肾细胞癌)的表面表达，并引导从表面到细胞内的内体隔室的运输。我们已经展示了放射性核素抗体结合物对CD74+B细胞的强大活性，使用快速内化的LL1抗体来靶向标记有俄歇电子发射体的CD74。这些结果为检测LL1-抗CD74单抗的药物传递提供了动力。阿霉素是治疗非霍奇金淋巴瘤的关键药物，它为药物结合疗法提供了许多优点，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；(C)具有多种作用机制，包括抑制拓扑异构酶II、插入DNA和破坏细胞膜。LL1-Dox在系统性非霍奇金淋巴瘤异种移植模型中的治疗效果突出(见初步结果和附加手稿)。非霍奇金淋巴瘤(NHL)是美国第五大常见癌症，每年占所有与癌症相关的死亡人数的5%。5年治愈率只有50%。众所周知，这些肿瘤表达大量的CD74抗原。非霍奇金淋巴瘤可能对使用药物-抗体结合物的特定靶向方法反应最好，因为其广泛传播的性质和癌细胞对全身给药药物的相对可及性。此外，造血肿瘤的内在敏感性更高，这是这种疾病的自然过程，细胞生长失控，最终数量超过正常B细胞，提供了与正常细胞相比，提供更高比例的注射药物-AB专门针对患病细胞的机会。因此，这项提案将使用几个已建立的临床前模型和原始NHL活检标本，解决LL1-Dox免疫结合物治疗播散性NHL的实用性。我们还将解决几个新的生物学问题，包括(A)通过直接使用抗体传递Dox来克服多药耐药(通常由60%的难治性NHL患者表现)的可能性，以及(B)克服与给予游离阿霉素相关的心脏毒性。

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.