Radioimmunotherapy plus chemotherapy shows promise for metastatic pancreatic ductal cancer

Small doses of an investigational radioimmunotherapy combined with small doses of the chemotherapy drug gemcitabine were shown to provide “superior outcomes” over radioimmunotherapy alone, according to research presented today at an American Association for Cancer Research conference, Pancreatic Cancer: Innovations in Research and Treatment.

“What [the research] attempts to do is explore the role of antibody therapy; antibodies as molecules that can target pancreatic cancer cells in this case, and deliver therapeutic agents to them,” Vincent J. Picozzi Jr., MD, director of the Pancreas Center of Excellence at the Virginia Mason Medical Center’s Digestive Disease Institute, said during a teleconference.

Vincent J. Picozzi Jr.

“The scientific name of the antibody is ⁹⁰Y-clivatuzumab tetraxetan, and to this antibody was bound a radioactive substance, yttrium-90, so the antibody carries radiation to the pancreas cancer cell, wherever it may be in the body. The thinking here is that radiation could be effective for pancreas cancer the way it is with most cancers,” Picozzi told callers. The antibody binds to the MUC5ac protein found on the surface of most pancreatic cancer cells.

Picozzi said 58 patients who had a minimum of two failed chemotherapy attempts were assigned to 6.5 mCi/m² ⁹⁰Y-clivatuzumab tetraxetan. Half of the patients were also assigned low-dose gemcitabine, with the hope that gemcitabine would act as a radiosensitizer to enhance the effects of the radiation, according to Picozzi.

“There seemed to be a survival advantage for patients using the combination of gemcitabine and radiation. This survival advantage, in the aggregate, was about a 40% improvement, which seemed to be amplified as time went on. In particular, patients who were able to receive two sequential courses of treatment … or more had a markedly improved survivorship over those patients treated without gemcitabine, such that their survivorship was more than double. In fact, [their survivorship was] longer than would be typically predicted for patients with previous treatment with gemcitabine,” he said during the teleconference.

Median OS was 3.9 months among patients assigned to combination treatment vs. 2.8 months among those assigned to radioimmunotherapy alone. After multiple cycles, median OS increased to 7.9 in the combination group vs. 3.4 in the radioimmunotherapy alone group (P=.004). According to the abstract, three patients in the combination group are still being observed.

What’s more, Picozzi reported the treatment was safe, with reduced platelet counts being the only real side effect observed.

“I think the significance of this study is that, number one, it demonstrates the feasibility of both clinical research and treatment for this group of patients for which there is no standard of care. Secondly, the use of the radio-labeled antibody either with or without gemcitabine can accomplished safely in a group of patients. Thirdly, [the study] suggests potential efficacy of the radio-labeled antibody and gemcitabine combination, which is now being tested in a much larger phase 3 trial,” he said. – by Shirley Pulawski

For more information:

Picozzi VJ. #B98. Presented at: AACR Pancreatic Cancer: Innovations in Research and Treatment; New Orleans; May 18-21, 2014.

Disclosure: This study was funded by Immunomedics, Inc. Picozzi reports no relevant financial disclosures.