By Lisa Seachrist
BETHESDA, Md. - Palatin Technologies Inc.'s appendicitis imaging agent LeuTech garnered a unanimous recommendation from an FDA advisory panel on Monday.
The Medical Imaging Drugs Advisory Committee voted 8-0 to recommend the FDA approve the radiolabeled drug as a means to diagnose appendicitis in patients whose symptoms neither rule out appendicitis nor clearly indicate the potentially fatal infection. The committee unanimously agreed Palatin showed LeuTech offered important additional clinical information in trying to decide whether a patient should be sent home, observed or undergo surgery.
"What the data show me is that this agent is helping us when we need the most help," said panel member Thomas Whalen, head of the division of pediatric surgery at the Robert Wood Johnson Medical School in Camden, N.J.
"We are ecstatic about the unanimous decision that LeuTech is safe and effective," said Carl Spana, CEO and president of Princeton, N.J.-based Palatin. "We are on track with our development and should be able to launch as soon after approval as possible."
LeuTech's marketing and launch will be directed by marketing partner Mallinckrodt Inc., of St. Louis, once manufacturing issues have been resolved and the product has been cleared for marketing by FDA. The panel's recommendation to the agency will weigh in the approval decision; however, the agency isn't bound by the advice of the committee.
"Mallinckrodt has made a significant commitment to this," Spana said. "They've been working on this for a year and have good insight into the product. I'm quite sure the 120-person sales force they've assembled is prepared for LeuTech's launch."
Palatin's stock (AMEX:PTN) closed Monday at $7.687, up 81.25 cents, or 11.8 percent.
Rather than a straightforward type of diagnosis, appendicitis can cause significant confusion for physicians and emergency room personnel because a large percentage of patients - as many as 50 percent - show atypical (equivocal) symptoms. Because an appendix that bursts spreads infection throughout the body and can be fatal, patients experiencing generalized abdominal pain, low white cell count and a low-grade fever present a quandary to physicians.
Palatin presented data to the panel showing LeuTech offered some guidance to physicians trying to make decisions on what do with such patients. LeuTech is a monoclonal antibody labeled with technetium specific for CD15, a cell marker found on cells involved in battling infections, such as neutrophils, monocytes and activated T cells, with neutrophils being the most important of these. The imaging agent is labeled at the hospital before it is injected into a patient's bloodstream. The patient's body is then scanned with a gamma camera.
The company told the panel one of the significant benefits of LeuTech is the fact the technique doesn't require physicians to draw blood, radiolabel the white cells in the blood sample, return the labeled white cells and scan the patient's body to track where the white cells go. LeuTech, instead, requires only the preparation, injection and imaging of the product.
The company presented data from Phase II and pivotal Phase III studies of LeuTech in patients with suspected appendicitis. The Phase III study included 203 patients who presented at the hospital with lower right quadrant abdominal pain and equivocal symptoms of appendicitis. LeuTech allowed for a quick diagnosis of appendicitis, with 50 percent of the patients with appendicitis having a positive scan within the first 10 minutes.
Perhaps more importantly, surgeons treating the patients changed their treatment plans in response to the LeuTech scan. Leutech indicated the need for surgery in three patients who would have been sent home. Conversely, five patients who would have had unnecessary surgery didn't have the surgery after imaging.
LeuTech didn't prevent all unnecessary surgeries. In addition, some patients receiving LeuTech experienced vasodilatation (flushing) as a response to the drug.
The FDA was particularly concerned about the possibility of patients developing human anti-mouse antibodies (HAMA) that would render the diagnostic useless after the first time it was administered. The panel, however, felt the issue could be addressed after marketing rather than requiring Palatin to conduct another clinical trial.
In the Phase III study, Palatin excluded any women with previously diagnosed pelvic inflammatory disease (PID). The panel recommended the agency tell doctors these women were excluded but didn't recommend the label specifically say LeuTech isn't indicated in such patients.
"It might be useful for physicians to know these patients were excluded," said panel member Mark Tulchinsky, a radiologist at the Milton S. Hershey Medical Center in Hershey, Pa. "I don't think the label should determine the practice of medicine. Saying the patients with pre-existing PID were excluded should be enough."
Palatin also is exploring LeuTech as a diagnostic imaging agent for the bone infection osteomyelitis, in diabetic foot ulcers, for ulcerative colitis and post-surgical infections.