Supporting Anti-Cancer Drug Development with Cultured Tumor Cells that Maintain Cancer Traits

Providing Research Results to Business

The TR Center supports efficient drug development by providing new cellular materials, information from various analyses, and others to the pharmaceutical industry and the testing and diagnostic agents industry. Additionally, it aims to generate employment in the Fukushima Prefecture.

The TR Center offers Biomolecular Profiling, Tissue Factory, Cell Factory, Gene Factory, Protein Factory, and Research Model Factory divisions, with more than 100 staff altogether.

The division of Cell Factory, where Associate Professor Hoshi works, uses patient-derived tumor organoids (PDOs) original to Fukushima Medical University (F-PDOs), cells derived from human iPS cells, and cell lines obtained from such sources as cell banks. These are used to construct highly accurate systems for evaluating the responsiveness and toxicity towards both available drugs and pharmaceuticals under development, and to conduct evaluations.

More than 70 varied kinds of F-PDOs have been established for various types of cancers, including: uterine cancer, ovarian cancer, and lung cancer, and progress is being made on evaluating their responsiveness to anti-cancer drugs. The drugs, and the responsiveness of human cells to those drugs will be incorporated into databases alongside their profiles.

In the case of cancer cells, tissues are collected from surgical specimens, biopsy specimens, ascitic fluid, or pleural fluid originating from patients who have consented to cooperate with the university hospital. These samples are first prepared for continuous proliferation at the division of Tissue Factory. Meanwhile, gene expression profiling is conducted for a portion of the specimen at the division of Biomolecular Profiling. Genome and protein analysis data is obtained at the division of Gene and Protein Factory respectively. At the division of Cell Factory, cells are used to establish new evaluation systems for anti-cancer drugs, and the efficacy of anti-cancer drugs is evaluated. Additionally, at the division of Research Model Factory, animal models are produced by implanting F-PDOs in immune-deficient mice, and these are then provided for evaluations of anti-cancer drugs.

The World-Class Fukushima Collections

The main differences between the Fukushima Collections and general “biobanks” are that, rather than simply collecting biological samples, they utilize the precious samples to their maximum extent by (1) converting them to data (gene expression, genome and protein analysis, etc.), (2) processing them for proliferation (patient-derived tumor organoids, tumor-bearing mice, etc.), and (3) developing trace sample analysis techniques (DNA microarrays, protein microarrays, etc.). Through these processes, it is possible to accurately evaluate anti-cancer drugs. The various data and cells that are gathered in the Fukushima Collections have begun to be provided to the pharmaceutical industry, the testing and diagnostic agents industry, and to research organizations.

Establishing Evaluation Systems from F-PDOs

Before Associate Professor Hoshi and his team actually started evaluating anti-cancer drugs, there were three main steps that had to be completed.

First, while establishing a culture system for F-PDOs is not simple, they have accomplished this. They have also confirmed that this system stably maintains the same characteristics as the original tissue (genome mutations, gene expression, and morphology). This point is extremely important. Next, Dr. Hoshi and his colleagues established a system that can evaluate drugs through inoculation with the above cultures.

The F-PDOs, which are produced from biological samples using an original technique, proliferate slowly and are more difficult to handle compared to general cancer cell lines; however, they retain properties that resemble the original tumor tissues. In contrast, general cancer cell lines are easy to handle, but it is difficult to maintain the characteristics of tumor tissues, and its responses in vitro do not necessarily reflect those of the original tumor tissues faithfully. Therefore, their responsiveness to stimulation with drugs may not correspond to the responsiveness of cancer tissue, and they may not be appropriate for experiments that stringently evaluate efficacy and other important factors.

Quality control, including the management of cell condition, is crucial to the subculturing of F-PDOs. Using the fully-automated cell analysis device, IncuCyte®, for observing cell health and proliferation simplifies the process of instantly identifying cells based on changes in morphology and monitoring growth rates

Dr. Hoshi said that, “In drug development, pharmaceutical companies want to evaluate drugs by using cells that reflect tumor tissues, rather than using general cell lines. The F-PDO collection is of a kind that is almost unheard of globally, and I would like to increase the number of F-PODs.”

Observing F-PDOs Over Time

Even if one obtains cultured organoids that reflect tumor tissue, because they proliferate by forming cell aggregations, they cannot be used as is. Usually, reagents and enzymes are used to disperse these; however, it was made possible to physically fragment and disperse aggregations by passing them through a micropore mesh, instead.

These fragmented cell aggregations are seeded into wells using a dispenser, with compounds added, and efficacy is observed. Observing whether cells are alive or dead involves measurement of ATP amounts derived from living cells, and the IC50 (50% inhibitory concentration) or GI50 (50% cell growth inhibitory concentration) is measured as an evaluation of a compound’s activity with respect to F-PDOs.

For example, an experiment was conducted using F-PDOs established from endometrial cancer, whereby the standard treatments for endometrial cancer, paclitaxel and carboplatin, and mitomycin C were each used to treat the F-PDOs and the cell survival rate after six days was observed. IncuCyte® was used for taking successive images of this, and the apoptosis-inducing activity observed and analyzed in parallel over time.

Dr. Hoshi said that, “General cancer cell evaluation methods only observe endpoints, so all kinds of things are overlooked. By making observations over time, it became possible to observe the detailed state during the process. It is possible to observe the time until apoptosis is induced and how responses differ depending on the concentration of the drug. There are drugs with a mechanism of action that changes over time, so this system is indispensable for evaluating drugs.”

F-PDOs exhibited poor sensitivity to paclitaxel and carboplatin, the standard treatments for endometrial cancer. Responses to these drugs were also poor in the patient, thus it was confirmed that the clinical efficacy was being reflected.

Contributing to Patients with Ground-Breaking Anti-Cancer Drugs

Dr. Hoshi was originally from Fukushima City and, after graduating from graduate school, he pursued drug development for cancer and immune diseases in the drug development department of a chemicals manufacturer. Subsequently, he made a U-turn for his hometown and took up a position at Fukushima Medical University. Having felt dissatisfied during his time in industry with the lack of available in vitro cell models that were able to reflect tumor tissues, he empathized with the significance of the new project.

Regarding his aspirations, he stated that, “I hope to contribute indirectly to the treatment of patients by having pharmaceutical companies steadily adopt our databases and systems and, in doing so, develop ground-breaking drugs.”

Now in its sixth year, the nine-year project has passed the halfway mark. There are plans for the Fukushima Collections to be provided overseas, broadening its user base not only in Japan, but globally; to solidify its foothold and allow it to become independent from the university in the future.

At present, anti-cancer drugs are the first-line treatment for some cancers, such as hematological cancers; however, as yet, there are no drugs that can substitute for surgery. Hopefully, the new methods that have the Fukushima Collections at the core, will open up the future of cancer treatment.