GDC-0449: From Corn Lilies to a CureBCCNS SymposiumSeptember 19.2009 Simon S. Yoo, MD Assistant Professor of Dermatology, Otolaryngology, and Surgery Feinberg School of Medicine Northwestern University
Corn Lilies & Cyclops • 1950s – Idaho sheep ranchers noticed strange birth defects • USDA – 11 years to discover the culprit • During droughts the sheep moved to higher ground to eat • Corn lilies
Cyclops • Corn lilies contained a poison, later called Cyclopamine (for obvious reasons) • When pregnant ewes ate the lilies their offspring would develop birth defects most notably the cyclops • 25 years past without any true explanation
Hedgehogs • 1970s Volhard and Wieschaus discovered 50 genes essential for fruit fly development (1995 Nobel Prize) • One gene when mutated caused flies to grow a coat of spines on their underbellies • Hedgehog gene
Sonic Hedgehog • 1993 Harvard scientists discovered a corresponding gene in mammals • Mutations caused everything from cyclops to single front tooth or slight deformity • Sonic hedgehog (Sega)
Light bulb • 1998 – Phil Beachy (JHU) remembered that there were strange lambs seen in Idaho in the 1950s • He wondered whether Cyclopamine could be used to induce changes in the sonic hedgehog pathway
Segue to Genetics • Genes exist in every cell • During development they conduct the orchestra that tells a single cell formed by a sperm and an egg how to become a human being • During cancer these same developmental genes can be activated and cause uncontrolled growth of certain cells
Sonic hedgehog tells the body how to develop a normal face during development of embryos • After development defects in these sonic hedgehog pathway can lead to cancer: • Basal Cell Nevus Syndrome was linked to a defect in this pathway relatively recently
Genetics of BCCNS • 2 proteins on the cell surface • Patch1 and Smoothened • Normally Sonic Hedgehog is not around in adults except during hair follicle growth in the skin • When it isn’t around the system stays quiet • However when there is a defect in Patch1 or Smoothened the system acts like Sonic Hedgehog is actually around and causes a number of effects subsequently that lead to tumors • Patch1 – tumor suppressor, Smoothened - proto-oncogene • BCCNS – heterozygote loss of Patch1 • Sporadic BCC – both loss of Patch1 and activating Smoothened
BCCNS Genetics There are 3 players at play in the sonic hedgehog signaling pathway: PTCH (or patch), SMO (smoothened), and SHH (sonic hedgehog). After development SHH is usually quiet except during hair follicle growth in the skin. If SHH is around, it can attach to PTCH and activate SMO to cause a number of events in the cell that can lead to cancer.
SHH and the cell cycle SHH can act via PTCH and other mechanisms to keep cells moving through their cycle leading to uncontrolled cell growth – a hallmark of cancer.
SMO and GLI SMO when activated works with another protein called GLI1 (Glioma-associated oncogene homolog 1 ) to cause increased cell proliferation and decrease apoptosis or cell death.
Cyclopamine Cyclopamine as well as GDC-0449 to inhibits SMO and therefore decrease cell proliferation and increase cell death.
Cyclopamine and GDC-0449 • Cyclopamine blocks hedgehog signaling by binding Smoothened • GDC-0449 is a small-molecule compound that is a selective hedgehog pathway inhibitor with greater potency and more favorable pharmaceutical properties and Cyclopamine
GDC-0449 • Antitumor activity in mouse model of medulloblastoma and human cell models of colorectal and pancreatic cancer
September 2, 2009 Inhibition of the Hedgehog Pathway in Advanced Basal-Cell CarcinomaDaniel D. Von Hoff, M.D., Patricia M. LoRusso, D.O., Charles M. Rudin, M.D., Ph.D., Josina C. Reddy, M.D., Ph.D., Robert L. Yauch, Ph.D., Raoul Tibes, M.D., Glen J. Weiss, M.D., Mitesh J. Borad, M.D., Christine L. Hann, M.D., Ph.D., Julie R. Brahmer, M.D., Howard M. Mackey, Ph.D., Bertram L. Lum, Pharm.D., Walter C. Darbonne, M.S., James C. Marsters, Jr., Ph.D., Frederic J. de Sauvage, Ph.D., and Jennifer A. Low, M.D., Ph.D.
Genentech Bio-Oncology Phase I Multicenter Trial of GDC-0449, evaluating efficacy and safety for advanced BCC
Introduction • Basal Cell Carcinoma (BCC) is the most common skin malignancy, usually effectively treated w/surgery • Small subset has aggressive, invasive disease • If further surgery not possible, no other approved therapy or standard of care • Metastatic BCC (mBCC) is quite rare (<0.1%) • Survival ranges from 8-14 mos to 5+ years (10%) • Metastatic sites: lymph nodes, lung, bone, liver, soft tissue • No approved or standard of care therapy exists for mBCC
Phase 1 Trial • Open-label, multicenter, 2 stage phase 1 trial • Evaluating safety and tolerability of GDC-0449 • 33 patients enrolled with metastatic or locally advanced basal-cell carcinoma • 17 patients received 150 mg/day • 15 patients received 270 mg/day • 1 patient received 540 mg/day
Eligibility • >18 yo • Histologically confirmed locally advanced or metastatic BCC considered to be refractory to surgical or radiotherapy • Negative pregnancy test • GDC-0449 was not started until >3 weeks after last therapy of surgery
18/33 - Metastatic disease • 15/33 – Locally advanced disease • Of those that responded most noticed a difference at 2 months
Exclusion • Major organ dysfunction • A long QT interval on ECG (or any medication known to prolong QT) • (e.g. Paxil, Effexor, Zomig, Prozac, Propulsid) • Active infection requiring IV antibiotics • Pregnancy • Inability to swallow drugs
Results • 18/33 - objective response (imaging, physical exam or both) • 2/18 complete response • 16/18 partial response • 11/33 – stable disease • 4/33 – progressive disease • 9.8 months – average treatment time
Results 2 • 18 Metastatic tumors – 50% responded • 15 Locally advanced tumors – 60% responded
Side Effects • 4/33 – Fatigue • 2/33 – Electrolyte imbalance (hyponatremia) • 1/33 – Muscle spasm • 1/33 – Heart palpitations (atrial fibrillation)
Relative Success • Because of the relatively low side effects and the relative improvement of the BCCs Genentech has begun a phase II trial
FDA and Drugs • Pre-clinical: test-tube and animal experiments • Phase 0: subtherapeutic or microdosing studies done to rank drugs in order to decide which ones should be studied further • Phase I: 20-50 subjects studied to assess safety, tolerability, and dose-ranging (usually healthy volunteers unless patients have terminal disease or lack other treatment options)
Phase II – 20-300 subjects to assess how well the drug works as well as to continue Phase I safety assessments (if new drugs fail they fail here) • Phase III – randomized controlled trials of 300-3000 subjects aimed at being the definitive assessment of how effective the drug is compared to current “gold standard” therapies
Genentech Bio-oncology Phase II Multicenter Trial of GDC-0449, evaluating efficacy and safety for advanced BCC
Inclusion Criteria • >18 yo • Histologically confirmed disease considered inoperable or medically contraindicated to surgery (as determined by Mohs, ENT, or Plastic Surgeon) • (multifocal superficial BCC is not considered inoperable)
Medical contraindications to surgery include: • BCC recurrence in same location after 2 or more surgical procedures • Anticipated substantial morbidity/deformity from surgery as determined the surgeon • Radiotherapy must have been tried in the past unless contraindicated (BCCNS are exempt)
Metastatic disease – histological confirmation of distant BCC • Generally good health
Exclusion Criteria • Pregnant/Lactating • Women who are of child-bearing potential must use 2 forms of birth control • No other experimental drug within past 4 weeks • No exposure to hedgehog signaling inhibitors previously • No history of other malignancies within past 3 years • No concurrent therapy (chemotherapy, radiation, photodynamic) • Life expectancy >12 weeks
Study Protocol • Screening – CT scan, biopsies, ECG, blood work, urine analysis, photographs • Patients seen every 4 weeks • Visits will continue until subject experience toxicity or withdraws from study • Medication is dosed every day • Photographs taken every other visit • Blood drawn every visit • Target lesions are re-biopsied at week 24 • Previously non-resectable tumors may be resected if approved
Acknowledgements • Murad Alam, MD – Northwestern University • Brenda Bartlett, MD – Northwestern University • Ivor Caro, MD – Genentech • David Kouba, MD, PhD – Henry Ford Hospital