血管肉腫を治療可能にするために、基礎研究を加速させる

 

｜Index

 

 

1：Our research project ~What is hemangiosarcoma?~

 

What is hemangiosarcoma?

Hemangiosarcoma (HSA) is a malignant tumor derived from the endothelium, which is the layer of cells that line the blood vessels. HSA frequently occurs in dogs, especially in the spleen, liver, and heart.

 

Tumors are the leading cause of death in dogs in Japan (Inoue M., et al. 2015), and more than 13,000 dogs lose their lives to HSA each year in Japan.* Moore AS. et al reported that the 1-year survival rate of dog patients treated by both surgery and chemotherapy was less than 16% (Moore AS., et al. 2017). Many dogs and their owners are suffering from the effects of HSA, but we do not have any effective treatment methods against this disease.

 

So, what about HSA in humans?

In human medicine, HSA is called angiosarcoma (AS).

Since AS is a very rare tumor, it is not well studied even in human medicine, and effective therapeutics have not yet developed.

In general, knowledge and findings can be applied from human cancer treatment to veterinary medicine; however, in this case, there is nothing available for HSA treatment.

 

In summary, there are still many unknowns in HSA and AS. We do not have basic information and knowledge of these diseases to develop effective therapeutics.

 

* There are 7,106,000 pet dogs in Japan. According to the company Anicom, the percentage of insurance claims due to cancer is 6.7%. If this ratio is applied to all dogs in Japan and considering the report that HSA makes up 2.8% of all canine tumors, the number of dogs affected with HSA is calculated as below.

7,106,000 (dogs) x 0.067 x 0.028 = 13330.86 (dogs)

(References: ペットフード協会2021年全国犬猫飼育実態調査，アニコム社家庭どうぶつ白書2021，Grüntzig K, et al. 2016)

 

Comparative pathology, a study useful for not only animals but also humans.

I studied infectious disease when I was an undergrad and embryology when I was PhD student. When I joined the lab of Comparative Pathology as an assistant professor, I wanted to conduct  research on “comparative pathology” because I wanted to do something that could only be done at a veterinary school.

 

Comparative pathology means that veterinary pathology can contribute to not only animals but humans. Based on this, I selected HSA for my research topic.

 

As I described above, there are no effective treatments for HSA even though it is an aggressive malignant tumor. I have been making effort to achieve my goals, to make HSA a treatable tumor by hemangiosarcoma research and to save not only animals but also humans, even from the standpoint of veterinary medicine.

 

The research did not go well at the beginning because I did not have any experience of cancer research. To overcome this, I went to the U.S. and studied at Yale University under Dr. Qin Yan’s supervision for two years. I gained the knowledge and skills required for cancer research. Now, I have strong support from Tamami, a PhD student in our lab, and Drs. Kim and Kinoshita, veterinary oncology experts in our animal hospital.

 

 

This project will uncover the mysteries that make HSA a malignant tumor, and we will build the foundation for the development of novel therapies.

HSA research is now at the stage of basic study. To move to the next step, the following two points are required.

1. To understand how HSA cells proliferate in animals
2. To produce results that can be applied to dog patients

 

 

Accomplishment of this project will give us results that can be applied to treatments with better outcomes. We will register our data on a public database so that other researchers can use it for further HSA research. I hope this will accelerate HSA research throughout the world.

 

Our research can also contribute to AS in humans.

This is because AS is a very rare tumor in humans, which makes it difficult to conduct AS research.

 

AS occurs in the skin. The Japanese Dermatological Association calculated that approximately 320 people are diagnosed with AS each year (皮膚血管肉腫診療ガイドライン2021). Considering the number of canine HSA cases is calculated as 13,000 dogs, it becomes clear how rare AS is.

 

On top of this, one research reported that HSA accounts for 2.8% of all tumors in dogs (Grüntzig. K et al. 2016), while the percentage of AS in humans is calculated as 0.03%.* Therefore, (hem)angiosarcoma develops 100 times more frequently in dogs than humans.

 

The high frequency of canine HSA means that many dogs are suffering from this disease. However, this also means that HSA research can get people’s attention and we can obtain a lot of information, data, and samples to conduct research.

 

Furthermore, several reports found common genetic mutations between HSA and AS, and they expect similar mechanisms are related to tumor development. Therefore, our results are highly expected to contribute to human AS, too.

 

* The ratio of sarcoma in human cancers is 1%. The ratio of AS in sarcoma in humans is 3%.

1% ´ 0.03 = 0.03%. (Reference: National Cancer Center Japan, National Cancer intelligence Network, 2012)

 

Thus, the achievement of this project will greatly pave the way for further HSA research. We need your support to save HSA dog patients, their owners and people suffering from AS.

 

 

３：What we can do with your support  ~Our research so far and future~

 

What we can do with your support

We are going to generate (1) patient-derived xenograft (PDX) model of HSA. Then, by using the PDX model, we will conduct (2) single-cell gene expression analysis to obtain the results that can lead us to novel therapeutics. Furthermore, we will perform (3) spatial gene expression analysis to unveil the pathogenesis of HSA in more detail.

 

Your support will allow us to do (2) single-cell gene expression analysis and (3) spatial gene expression analysis. Thus far, basic data on all gene expressions in HSA has been collected by experiments using cultured cell lines. There have been no reports investigating all gene expressions in HSA at single-cell level.

 

These experiments will give us results to allow high enough expectations for clinical application.

 

The reason we need your support

Both single-cell gene expression analysis and spatial gene expression analysis require approximately 1 million yen (≈ $7,000). We are supported by a research fund (JSPS KAKENHI), but only 1.1 million yen (≈ $7,500) is available per year, which can cover only one experiment for either analysis.

 

We cannot fail the experiments because they cost a lot. To make them successful, we always carefully consider the experimental conditions and perform preliminary experiments before conducting the main experiments. In addition, we need money for data analysis, validation, and additional confirmation experiments.

 

Target figure and experiment schedule

◆ Target figure

The 1^st goal: 2 million yen (≈ $14,000) for single-cell gene expression analysis

The 2^nd goal: 4 million yen (≈ $28,000) for spatial gene expression analysis

* Costs for preliminary experiments, data analysis, validation, and additional experiments for both analyses are included.

 

 

◆ Experiment schedule

We plan the following schedule in 2023 – 2025.

 

We can use 1.1 million yen (≈ $7,500)/year until the end of 2024, but we may not be able to get further support if we do not produce positive results. To save HSA dog patients and people, we think that HSA research should be accelerated now even if lots of costs are required.

 

 

If this project will be accomplished and we can get many meaningful results, we will be able to apply for larger research grants. We decided to launch this project to get your support and to be able to conduct HSA research for several years.

 

 

Results so far

We started canine HSA research using culture cell lines. We identified genes required for HSA cell proliferation and chemicals that can suppress HSA cell line growth (Gulay KCM, et al. 2021. Suzuki T et al. 2022).

 

However, culture cells are used on a plastic dish which provides a completely different condition from inside of animal’s body. To understand the characteristics of HSA precisely, we need to investigate how HSA cells act within animal’s body.

 

 

Future plans

(1) HSA PDX library creation

PDX models reconstruct HSA in immunodeficient mice by transplanting HSA tissue fragments collected from dog patients.

 

Unlike cell lines, PDX models do not require long-term culture on plastic dishes, so HSA cells proliferate in mouse bodies while keeping their original characteristics. Therefore, by using HSA PDX models, we can conduct research focusing on the original HSA characteristics and can provide results with high expectations for clinical applications.

 

(2) Single-cell gene expression analysis using PDX models

Tumors are not composed of single type of cells, rather various types of cells such as actively proliferating cells and drug-resistant cells. This is called as tumor heterogeneity. We need to understand tumor heterogeneity to develop effective treatment methods so that we can target different types of cells.

 

Single-cell gene expression analysis allows us to investigate how many genes are functioning in each tumor cell at the single-cell level. Through this experiment, we will identify the mechanism by which tumor cells can survive and proliferate in animal’s body.

 

(3) Spatial gene expression analysis using PDX models

The surrounding environment of each tumor cell is different even within a tumor tissue. For example, he properties of tumor cells close to blood vessels and those deep in the tumor tissue are very different.

 

We can obtain information about where tumor cells are located within the tumor tissues and with which cells they coexist. This information allows us to correctly understand the characteristics and properties of HSA tumor cells.

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In addition to these analyses, PDX models can be used to examine the efficacy of existing or novel drugs on HSA.

By evaluating the efficacy of drugs such as those used for human medicine or for other canine cancers by using the HSA PDX model, we can find drugs with high expectations for HSA treatment in dogs.

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In veterinary medicine, drugs for humans are often used to treat animals.

While we often apply human drugs to dogs directly, PDX models allow us to investigate drug efficacy beforehand. The same results are highly predicted in dog patients.

 

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4: Our research goal

There is no report about single-cell gene expression analysis and spatial gene expression analysis for HSA. We believe that the results obtained by these experiments are highly applicable and will accelerate HSA research further.

I was struggling to win funding at the beginning of my HSA research because I did not have any results or published papers. I also applied for some research grants provided by private foundations, but was not selected.

(* Most research grants for basic medicine and life sciences target those for human health or unveiling the biological mechanisms. In Japan, there is no research grants targeting basic studies to develop novel therapeutics for companion (pet) animals. It is quite difficult for our HSA study to obtain research funds from private foundations.)

I began wondering whether my study could contribute to society because I did not get enough research funds for such a long time.

Nevertheless, we conducted research and published a press release about our results on HSA pathogenesis in 2021. Since then, I have received many calls and emails from owners whose dogs were diagnosed with HSA. People suffering from AS also sent me emails.

However, our project is still at the basic research stage and our results cannot yet be applied toward treatment. I have felt very distressed that I must tell pet owners and patients so every time. This experience motivated and made me realize that our research can indeed contribute to the society.

The final goal of our research is to develop novel effective therapeutic methods for HSA.

We always keep this goal in mind and conduct research to be able to find novel therapeutic targets with high expectations for clinical application. We also aim to advance this research to preclinical and clinical study stages, thereby contributing to society direct