AACE 2011: New Ways to Tackle Less Common Cancers (and Take Them Out)
Daniel Von Hoff, MD, discussed novel treatments for rare cancers at the AACE annual meeting.
In one of the “hot topic” sessions at the 20th Annual Meeting and Clinical Congress of the American Association of Clinical Endocrinologists, Daniel Von Hoff, MD, spoke on novel treatments for some of the more rare cancers. Von Hoff is physician-in-chief, distinguished professor at the Translational Genomics Research Institute (TGen), professor of medicine, Mayo Clinic, and chief scientific officer, US Oncology Research & Scottsdale Healthcare. He took a decidedly patient-focused approach during the session and described several case studies.
“Everything we do begins with patients,” he began. Von Hoff shared in the frustrations of many physicians, particularly endocrinologists, who say, “No one will develop a drug for our patients with the types of cancers we see.” He told the story of the development of imatinib, which was discovered through research led by Brian Druker, MD, and is used to treat chronic myelogenous leukemia (CML). The Philadelphia chromosome, which is characterized in CML, was discovered in 1960. It took 41 years before imatinib was approved.
Von Hoff’s research focuses primarily on phase 1 development. All of the patients seen in Von Hoff’s practice have exhausted all standard therapies for their cancers and are typically in their last 12 weeks of life. He admitted that he often lets patients down despite his best efforts. However, in the last few years, multiple new anticancer agents have been approved, lending much promise to treating various cancers. Among these agents are vandetanib for medullary thyroid cancer, XL 184 which inhibits multiple receptor tyrosine kinases, motesanib which inhibits VEGF receptors, thalidomide and lenalidomide for multiple myeloma, BRAF mutation drugs such as PLX4032, and axitinib, another tyrosine kinase inhibitor. In fact, each year, 37-40 new anticancer agents with different mechanisms of action are in clinical trials.
Molecular profiling (MP) can also be used to identify treatments. Von Hoff described a study with 112 patients, whom he labeled as “target now” due to their urgency. Of these, 74% had at least one potential molecular target identified (eg, ER). “Even with extensive prior treatment,” he explained, “patients may have tumors with potential molecular targets.” Using treatments suggested by MP, doctors can keep patients alive longer. In a study with 66 patients, treatment was determined based on whether or not a target was found. If a target was found, the patient was treated accordingly. If a target was not found, the patient was treated according to doctor’s recommendations. Out of 66 patients treated according to MP, 27% were successfully treated, with a progression-free survival greater than 1.3 years. “No one is naïve enough to think that this type of simplistic profiling and targeting would be a big advance,” he said, “but it is important to pursue because it gives us information about patients for right now.” This is especially relevant when dealing with patients in their last weeks of life.
Von Hoff described research related to the hedgehog pathway. In a growing embryo, this pathway provides cells with information to help the embryo develop normally. When the pathway malfunctions, it can result in diseases such as basal cell carcinoma and medulloblastoma. This malfunction may be caused by mutations in the hedgehog receptor PTCH gene. Von Hoff encouraged sequencing of cancers, as it may alter diagnoses. He cited two examples, one in which a misdiagnosis of cancer (different type of cancer) was discovered after rebiopsy, and one in which a fungal infection was mistaken for cancer.
“It is critical to measure each patient’s refractory cancer and do careful molecular work because it may lead to new targets, new agents, and new progress.”