Monoclonal antibodies that target the immunogenic proteins expressed in colorectal cancer.

In an attempt to improve upon the end results obtained in treating colorectal cancer it was apparent that the earlier the diagnosis that could be obtained, the better the chance for obtaining desired results. In the case of more advanced tumors typified by later stage colorectal cancer, surgical debulking is an important part of the treatment strategy. Here the use of additional therapeutic modalities including chemotherapy and present day immunotherapy has failed to accomplish the desired improvements that have been sought after. Adjuvant therapy, has offered little to the overall survival. The concept of early detection is now recognized as the initial step in reaching proper end results and can readily be demonstrated from colorectal cancer studies. Here survival has been found to be a reflection of the stage at which the tumor is first identified and treated. When specific monoclonals targeting colorectal cancer are employed diagnostically, we have been able to demonstrate detection of colorectal cancer at its inception as a premalignant lesion, such that genotypic features can be identified before the phenotypic appearance of cancer can be noted.

Optimizing the immune system to achieve control of the metastatic malignant lesion.

In a recent issue of Nature, an article appeared discussing the issue of "Sizing up a slow assault on Cancer" (Nature 2013;496:14-15). This article attempted to clarify various approaches that the clinician might employ in bringing cancer under control. It also discussed the role of the immune system with regard to its capability for controlling tumor growth. In addition, it covered possible directions that might be taken to improve present responses to immunotherapy based on utilizing T-cell activity directed against the tumor. While there is some validity to the concept that cell mediated immunity is utilized by the host in its attempt to control evolving malignancy, this process actually represents only a minor role taken by the hosts immune system to accomplish what is needed for tumor control. Clinical studies at Precision Biologics have demonstrated that for tumor growth to be effected properly by the hosts immune system, expression of a specific humoral IgG1 response directed against immunogenic tumor glycoproteins on the cell surface membrane, constitutes the primary method needed for tumor control. Failure to obtain significant levels of the needed IgG response almost invariably results in recurrence and progression of disease.

Nanocytology vs. Immunohistochemistry of Intestinal Colonocytes to Assess the Risk of Colon Cancer based on Field Cancerization - A Preliminary Report.

The ability to define malignancy in its earliest stages of development is an essential part of any program aimed at attempting to cure the malignant condition. In terms of colon cancer various approaches have been employed to define the transformation of colonocytes as they progress to the fully malignant phenotype. Approaches ranging from nanocytology to mass spectroscopy have been utilized with limited success.Our group at Precision Biologics has been able to define three distinct immunogenic proteins, most oncofetal in origin, which are expressed to various degrees in colon cancer and are essentially absent from normal colon tissue. Monoclonal antibodies (mAbs) have been developed against these tumor associated antigens (TAA), which is NPC-1, 31.1 and 16C3. Each, have shown significant ADCC in the presence of the tumor cells grown in culture. Studies were performed to clarify at what stage in the development of the colon cancer do such TAA proteins begin to be expressed. Utilizing Immunohistochemistry (IHC) with the mAbs targeting the TAA's, we have been able to demonstrate that such antigens appear in the cytoplasm as early as 6 or more months prior to the phenotypic appearance of malignancy utilizing H&E staining.Kits containing these colon Ca monoclonals from our lab, as well as positive and negative controls have been produced for use in the operating room to examine colonocytes at the margin of resection following colectomy; this in order to assure that transforming cells are not incorporated into an anastomosis. We have also been able to demonstrate that premalignant cells as well as those cells present in a fully malignant lesion do shed their antigens into the lumen of the bowel. As such, we have been able to show that a simple "office" stool ELISA can predict with a high degree of accuracy whether a premalignant polypoid lesion, a fully malignant adenocarcinoma or a totally normal colon free of any neoplastic process is present and thus decide on the need for or not, of performing colonoscopy.

The use of specific monoclonal antibodies to target immunogenic tumor membrane proteins in patients with recurrent pancreatic and colon cancer.

Tumor associated antigens from pooled allogeneic membrane proteins were isolated, partially purified and tested as a possible vaccine in patients with stage II and III colon cancer. The vaccine, when given in combination with an adjuvant following surgical resection, resulted in marked improvement in survival compared to control patients having only undergone surgical resection of their tumor. While it was possible to demonstrate that patients receiving vaccine turned on both humoral and cell mediated responses, it appears that survivors remaining free of disease at 5-7 yrs post op were able to mount a strong IgG1 response as the primary mechanism for tumor destruction. Antibodies from hybridomas made against the vaccines resulted in production of monoclonals with a high degree of ADCC. Those monoclonals targeting pancreatic cancer and in particular the MUC5ac mutated antigen representing tumor immunogen were studied in detail. Animal models indicated rapid tumor destruction when nude mice, injected with human pancreatic cancer were then immunized with NPC-1 monoclonal antibody targeting mutated MUC5ac. FDA studies including tissue cross reactivity, biodistribution, and cytokine release assays indicated safety and efficacy of the monoclonals we have developed. Submission of the IND allowed for initiation of the Phase I trial using mAb NPC-1 targeting pancreatic cancer when that antigen was found to be expressed.

Infiltrating ductal carcinoma of the breast associated with primary breast lymphoma.

We report on the development of an uncommon association of pathologic processes, where an invasive adenocarcinoma of the breast developed concomitantly with a primary lymphoma arising in the same breast. The patient, a 78 year old female, presented with two palpable breast lesions in her left breast and an additional lesion in the right breast. Core needle biopsies of the lesions revealed both ductal carcinoma and lymphoma existing adjacent to each other in the left breast and a second primary lymphoma in her right breast. The mammogram, which also defined the lesions, illustrated collision tumors of the left breast and a separate pathologic process in the right breast. Excision of the lesions confirmed the two independent lesions on the left side, one an infiltrating ductal carcinoma and the second a large B-cell lymphoma. Biopsy of the right breast also demonstrated existence of a large B-cell lymphoma. Left axillary biopsy using sentinel node technology indicated that there was no evidence of nodal metastasis. The question arose as to possible etiologic factors related to viral transfection at the DNA level, that could cause transformation within the ductal epithelium of the breast with similar transfection of the lymphocytes of an adjacent intramammary node, that led to the development of the simultaneous pathologic processes of ductal carcinoma and B-cell lymphoma, defined on biopsy.

The therapeutic value of monoclonal antibodies directed against immunogenic tumor glycoproteins.

Monoclonal antibodies developed against immunogenic proteins (Tumor Specific Antigens/TSA's) that are expressed in human cancers, display a unique behavioral pattern. They appear to serve in a dual role. This includes the early recognition of these immunogenic membrane proteins that can serve as diagnostic markers, and the targeting of such markers for the destruction of the tumor, primarily thru ADCC.The monoclonals (mAbs) that we have developed against specific immunogenic tumor membrane proteins have been studied in detail. These tumor proteins, when first defined, were referred to as tumor associated antigens. With the ability of the mAbs to demonstrate therapeutic antitumor activity in those patients with relatively advanced malignancies, the term tumor specific was introduced. Monoclonals that we were able to develop from tumor specific proteins derived from colon and pancreas cancer were found capable of targeting those tumors to induce apoptosis. We were also able to define immunogenic membrane proteins from lung (squamous and adenoCa) as well as prostate neoplasms. Monoclonals developed from these tumor antigens are in the initial phases of investigation with regard to their specificity and antitumor activity.Mabs capable of targeting the malignancies noted above were produced following immunization of BALBc mice with the Tumor Specific Antigens. The hybridomas that were screened and found to express the antibodies of interest appeared for the most part as IgG2a's. It became apparent after a short period of time that stability of the Fab CDR loops as well as the therapeutic efficacy of the hybridoma mAbs could be lost. Stability was achieved by chimerization and or humanization. The resulting mAbs were found to switch their isotypes to an IgG1 subsequent to chimerization and or humanization, when expressed in CHO cells. The monoclonals, so produced, were not only more efficient in controlling tumor growth but minimized the development of a HAMA response.Because of 1) the specificity of this group of monoclonal antibodies in targeting well defined immunogenic proteins that were expressed on the tumor cell membrane,2) their lack of cross reactivity to normal tissue, 3) relatively low toxicity when delivered intravenously, 4) rapid targeting of tumor cell populations (4-6 hrs in vitro) and their 5) ability to destroy xenograft transplants (in vivo) within days of delivery, these mAbs were felt to be ideal for possible use in the treatment of patients with recurrent and or metastatic tumors.Initial clinical studies have been planned for following the filing of an IND. It is required by FDA that the potential effects of tumor control and toxicity be defined using the naked antibodies produced under GMP conditions, In those situations where patients with recurrent malignancies are to be studied we have come to realize that a number of factors can influence the response to monoclonal therapy. This includes the amount of shed antigen in the serum at the time of treatment that could initiate immune complex formation as well as the shedding of inhibitory material into the serum possibly effecting an immune response. As such we plan to eventually employ the therapeutic mAbs in combination with chemotherapy as a means of enhancing the immunogenicity of the tumor system being treated and to possibly weaken the malignant growth for easier destruction by the mAb. We will also look at the combination of mAbs with immunostimulants such as GMCSF and IL-2 (fusion proteins) and eventual conjugation of the mAbs with alpha and possibly B-emitters to help in targeting bystander cells. The present paper reviews the potential therapeutic value of such mAbs in the treatment of recurrent malignancies, especially those having failed chemotherapy in established clinical trials.