Detecting Early-Stage Pancreatic Cancer

According to the National Cancer Institute, pancreatic cancer is the fourth leading cause of cancer death in the United States. For patients with advanced cancers, the overall 5-year survival rate of all stages is less than 1%. For those patients with small and localized disease that can be completely resected surgically, 5-year survival rates improve to 18% to 24%. Although early detection and diagnosis is key for survival, it is rare to detect this lethal cancer early because pancreatic cancer symptoms are vague and the disease tends to develop and grow silently. By the time it is detected, it has often spread to other parts of the body, making it nearly impossible to cure. Currently, the standard therapy for pancreatic cancer is gemcitabine, alone or in combination with other chemotherapeutics.

Figure 1. Age-Standardized death rates from Pancreatic cancer by country (per 100,000 inhabitants).

A new immunoassay can detect early pancreatic cancer with fairly high specificity and sensitivity, according to researchers. The new immunoassay is based on the antibody PAM4 and detects pancreatic ductal adenocarcinoma (PDAC) (1-3). It correctly detected stage 1 PDAC in 18 of 28 patients (64%) previously diagnosed with the disease at that early stage. These patients were a subset of a larger group of confirmed PDAC patients with all stages of disease. The PAM4 immunoassay was able to correctly detect 76% of this larger group of PDAC patients (225 of 298). Dr. Gold and his team combined the PAM4 immunoassay with the CA19-9 immunoassay, which is commonly used to monitor the course of the disease. Together, the 2 immunoassays were able to detect 85% of patients with PDAC.

Immunomedics, Inc., a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other diseases, today reported that a new blood test using the Company's proprietary humanized antibody, clivatuzumab or PAM4, predicted a partial response in an initial set of patients treated with a combination of the antibody labeled with yttrium-90 (Y-90) and gemcitabine (5). The authors have demonstrated that the blood assay for PAM4-protein can not only detect early-stage pancreatic cancer, but may also predict a lack of response to therapy or an early relapse.

At the recent 2010 ASCO-GI Symposium, the Company reported an overall response rate of 68% with 5 patients having a partial response (PR), 10 with stable disease (SD) and 7 with progressive disease (POD). (For more information on the Phase Ib/II studies of clivatuzumab as a treatment for patients with pancreatic cancer, please refer to the Company's press releases at: http://www.immunomedics.com/news-2012.shtml). Although these results are based on a small number of patients, the trend is encouraging and may be predictive of response to other therapies (4-6).

PAM4 is an antibody that recognizes a specific biomarker (MUC1) made almost exclusively by pancreatic cancer. Developed by Dr. David V. Gold, the antibody was reported to detect an elevation of this biomarker in the blood of over 80% of patients diagnosed with pancreatic cancer. Animal studies with transplanted human pancreatic cancer demonstrated that PAM4, radiolabeled with yttrium-90, had a very strong effect in reducing tumor growth, even curing some animals. Although the radiolabeled PAM4 antibody was superior to gemcitabine alone, the combination of radiolabeled PAM4 antibody and gemcitabine was more active in controlling pancreatic cancer growth than either agent by itself, thus suggesting synergistic effects (7). Human tests with clivatuzumab are ongoing.

Reference:

1. http://www.medscape.com/viewarticle/757055
2. David V. Gold et al., (1994) International Journal of Cancer, 57; 204–210.
3. Gold, D.V. et al., (2007) Clin Cancer Res 13; 7380
4. http://www.asco.org/ASCOv2/Department%20Content/Communications/Downloads/2012%20GI%20Research%20Release.pdf
5. http://www.news-medical.net/news/20100421/Immunomedics-blood-assay-for-PAM4-protein-can-detect-pancreatic-cancer-and-predict-early-relapse.aspx
6. Gold DV, et al., (2003) Clinical Cancer Research 9: 3929s-3937s
7. Karacay H., et al., (2009) J Nucl Med. 50: 2008-2016..

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