Weill Cornell’s Dr. Scott Tagawa presented four research posters at this year’s American Association for Cancer Research (AACR) annual meeting. Each of the presentations is summarized below. Click on the title to view the published abstracts.
Non-invasive measurement of prostate-specific membrane antigen (PSMA) expression with radiolabeled J591 imaging: a promising biomarker for PSMA-based radioimmunotherapy
J591 is a man-made monoclonal antibody that is able to recognize a protein antigen (PSMA) expressed on virtually all prostate cancer cells, and more so in men with treatment-resistant metastatic disease. When a tiny tag of radioactive material is attached to the J591 antibody, that specifically targets prostate cancer cells, and delivered systemically this is known as radioimmunotherapy. Dr. Tagawa has been conducting clinical trials of the precision radioimmunotherapeutic J591 to determine its ability to eradicate prostate cancer cells that have metastasized. In this poster presentation, Tagawa and colleagues performed a combined analysis of four clinical studies of this radioimmunotherapeutic that examined 130 patients with metastatic treatment-resistant prostate cancer. They found that the levels of PSMA expression—as determined by a non-invasive scan–can be used to indicate response to their radioimmunotherapy.
ERG induces taxane resistance in castration-resistant prostate cancer
Taxanes are a type of chemotherapy drug that are used to treat advanced prostate cancer; however, inevitably prostate cancer patients develop resistance to these chemotherapy drugs. In this poster, Tagawa et al demonstrate that a genetic abnormality (ERG positivity) found in half of all men with prostate cancer plays an active role in inducing resistance to taxane-based chemotherapeutics. Additionally they’ve determined that men with ERG positive tumors have upregulation of another protein (clusterin) that can cause resistance to taxane chemotherapeutics. This work dovetails nicely with Dr. Zoubeidi’s work (see above) and shows the potential to use a drug now in clinical trials (OGX-011) to enhance response to chemotherapy in men whose prostate cancer is positive for the ERG genetic aberration.
Using CTCs to interrogate mechanisms of taxane resistance in the prospective TAXYNERGY clinical trial in prostate cancer
This poster describes a prospective, randomized multi-site clinical trial that will enroll 100 men with treatment resistant prostate cancer and use advanced technology to capture and analyze cancer cells that are freely circulating in their bloodstreams. This trial will allow the researchers to look for early signs of treatment response or failure in individual cancer cells and examine the genetic and other molecular factors that indicate or lead to either a response or lack of response to chemotherapy. This is one of the few studies to utilize blood-based biomarkers in a prospective fashion. It is also a demonstration of cooperation between academic partners and the pharmaceutical industry—one that was facilitated by the Prostate Cancer Foundation.
Prostate circulating tumor cells metastasize to bone via E-selectin expressed on endothelia cells
This poster describes a molecular dance that prostate tumor cells exploit as they metastasize to bone. Understanding and characterizing the mechanisms that tumor cells use exit the bloodstream and to home to bone and set up shop should allow researchers to develop ways to interrupt the process and prevent circulating prostate cancer tumor cells from setting up cancerous shop in men’s bones.