PharmaCyte Biotech, Inc., a clinical stage biotechnology company, announced that it has successfully completed the “pore size studies” on its Cell-in-a Box capsules that are required by the US Food and Drug Administration (FDA).

PharmaCyte’s chief executive officer, Kenneth L. Waggoner, explained the significance of the study saying, “PharmaCyte’s treatment for locally advanced, non-metastatic, inoperable pancreatic cancer (LAPC) utilizes genetically engineered live human cells that produce a particularly potent cytochrome P450 enzyme that is able to activate the chemotherapy prodrug ifosfamide. These cells are encapsulated using the Cell-in-a-Box technology, and the capsules are implanted near the cancerous tumor so that a high local concentration of the cancer-killing ifosfamide metabolite is produced near the tumor.

“Therefore, it is essential that the ifosfamide can easily and quickly enter the capsules so that it can be efficiently converted into the ifosfamide tumor-killing metabolite. It is equally important that this metabolite can then exit the capsules and destroy the tumor. The completed studies clearly demonstrate that this is the case and underscore the stability of the capsules over the freezing, transport and storage cycle.”

As part of PharmaCyte’s Investigational New Drug Application (IND) for its clinical trial in patients with LAPC, the FDA required PharmaCyte to provide data showing that the size of the pores in the outer shell of the Cell-in-a-Box capsules is appropriate to allow ifosfamide to enter the interior of the capsules where the ifosfamide-activating cells are located. Additionally, PharmaCyte is required to provide data showing that the pores are also of appropriate size to allow the activated form of ifosfamide to leave the capsules.

The FDA also required PharmaCyte to conduct experiments to demonstrate that the pore size was not affected by the freezing and thawing process of the capsules. To provide the information required by the FDA, a series of laboratory experiments were performed with non-frozen and freshly thawed capsules that were previously frozen and that contained labeled particles. Each set of samples studied contained particles of a particular size, and the appropriate size range was covered by the series of experiments.

Both the release of the particles from the capsules over time and the accumulation of the particles outside the capsules over time were evaluated. The experiments clearly demonstrated that molecules of the size of ifosfamide or its activated cancer-killing form could pass through the capsule’s pores virtually instantaneously. Further, there was no difference detected in the release parameters between freshly produced capsules and those that had been frozen and then thawed.