A new trial down the “Hedgehog” pathway for men with high-risk prostate cancer

Nearly ten years ago, Johns Hopkins researchers David Berman and Philip Beachy discovered the hedgehog pathway in mice with prostate cancer.[1] This molecular pathway is turned on in the embryologic development of lung, pancreas, prostate, brain and other organs during normal development. In prostate cancer, this pathway is abnormally turned "on" as prostate cancer grows and spreads. Patrick C. Walsh, MD, describes the pathway, "It's like soil and seeds. The soil is the stroma of the prostate — the connective tissue that serves as its framework — and the cancer cells are the seeds." And the Hedgehog protein is compost, sunlight and water — everything the seeds need to grow. "If these cells spread but try to grow in poor soil, they can't survive. But if they can manufacture the Hedgehog signal, they can make the soil that they need — they can pack their lunch and take it with them."

In their original study, published in Nature,[1] Drs. Berman and Beachy demonstrated that giving drugs that could block the Hedgehog pathway, could shrink human prostate cancer tumors in animals. That model is now ready for prime-time testing in humans. Dr. Ashley Ross, MD, PhD, Assistant Professor in Urology, Oncology, and Pathology, is partnering with Emmanuel Antonarakis, MD, medical oncologist, are opening a randomized, placebo-controlled clinical trial of a highly selective Hedgehog pathway inhibitor, called LDE225 and made by Novartis. Dr. Ross explains the hypothesis of the trial:

Ashley E. Ross, MD, PhD

"By looking at gene expression patterns, we and others have found that the Hedgehog pathway appears up-regulated in men with disease that metastasizes after local therapy. Also, in men with advanced prostate cancer, Itraconazole, which inhibits the Hedgehog pathway, appears to slow the disease by a mechanism independent of the androgen receptor. Itraconazole is an antifungal drug. Recently, new, Hedgehog pathway specific drugs with much more favorable toxicity profiles are available."

Men with high-risk prostate cancer are badly in need of a drug that could potentially prevent cancer growth and metastasis. In these patients, there is always the possibility that, even after surgery or radiation therapy, some cancer cells have already escaped the prostate, are hiding somewhere in the body, and will repopulate. Use of a systemic Hedgehog inhibitor may help wipe out these "micrometastatic" cells. Dr. Ross explains,

"We need to start thinking of high-risk disease as a different type of cancer, a systemic disease, and we have to start treating them like we treat other cancers, with a systemic approach in addition to surgery and/or radiation."

The trial is open to radical prostatectomy patients at Johns Hopkins with high-risk prostate cancer: men with a Gleason score of 8 to 10, a PSA of 20 or greater, or clinical stage T3 disease. The men who receive the drug will take the pill for four weeks before radical prostatectomy. All of the men will undergo a repeat biopsy and will have a molecular profile done on their cancer cells before surgery, and then will have the radical prostatectomy specimens examined afterward. Dr. Ross explains, "It's a pharmacodynamic trial, to see if this new drug actually gets into the prostate and inhibits the Hedgehog pathway as we expect it should. Of course, men will be followed closely following prostatectomy and we will also monitor whether superior cancer control results are achieved in those who received LDE225."

 

 
This blog and quotations are extracted from:
Target: Hedgehog Pathway, New Trial Opens for Men with High-Risk Prostate Cancer in Discovery, Volume XI, Winter 2015.

Hedgehog Blockers:Can They Stop Advanced Prostate Cancer? Scientists One Step Closer To Finding Out in Prostate Cancer Discovery, Volume II, Autumn 2005.

 
[1] Karhadkar SS, Bova GS, Abdallah N, Dhara S, Gardner D, Maitra A, Isaacs JT, Berman DM, Beachy PA. Hedgehog signalling in prostate regeneration, neoplasia and metastasis. Nature. 2004 Oct 7;431(7009):707-12. Epub 2004 Sep 12.