Cancer Research in 3D with Tumoroid Culture Medium

 

Exploring the tumor microenvironment (TME) through off-the-shelf tumoroid culture

by Kendra Atleework and Dana D’Amico 

“Cancer” is a six letter word that evokes a somber, universal understanding of a condition that affects nearly 20 million people globally each year. The simplicity of the term, however, disguises an incredibly complex disease process unfolding at the cellular level. Cancer is no one thing, but instead a vast umbrella of diseases triggered by the out-of-control proliferation of rogue cells. Individual cells, tumors, patients, and types of cancer each bring a new layer of idiosyncrasy.

In a perfect world, researchers would closely mirror these intricacies in the lab and develop cancer therapies that match their disease targets closely, thwarting the disease’s ability to throw a knock-out punch.

In reality, the gap between available research models and a real-life patient tumor has been wider than many scientists would have liked. Take, for example, the complicated relationship between the tumor and surrounding tissue known as the tumor microenvironment (TME). The TME is a three-dimensional space.

 

For decades, cancer research has looked like a monolayer of standard, immortalized cell lines culturing in a dish or more recently, suspended in spherical clusters. Traditional two-dimensional systems are simpler and more scalable at the bench but fail to capture both the real-life heterogeneity of tumors and the spectrum of their interactions with the 3D tumor microenvironment. Spheroid systems allow for 3D structure, but like traditional systems suffer from genomic instability via immortalized cell lines that have been cultivated in an artificial environment for longer than many of today’s cancer researchers have been alive. These decisions make for a challenging applied research landscape, and many new cancer drugs fall short in the clinical trial stage.

“When researchers get better at bridging the gap between the lab and the clinical setting, that makes a difference to patients,” said Erik Goka, Vice President of Biology at Revere Pharmaceuticals.

New, three-dimensional tumoroid cell culture approaches, made increasingly accessible by tools like the Gibco™ OncoPro™ Tumoroid Culture Medium Kit from Thermo Fisher Scientific, may finally signal a sea change for the field – a leap forward in understanding how cancer could grow inside the body and hopefully a step closer to developing lifesaving drugs and blocking cancer’s next punch.

 

Traditional cell culture models are two-dimensional. Tumors are not.

In an effort to understand cancer cells, tumor growth, and drug behavior, cancer researchers have historically relied on 2D cell culture of highly homogenous, immortalized cell lines. While 2D cell culture has facilitated progress, this method comes with a host of problems.

“Most 2D cell cultures grow on a plastic dish, which, as you can imagine, is nothing like the environment inside a human body,” said Goka.

Cancer cells are highly volatile to begin with, gaining more mutations the longer they proliferate. When cancer cells have been multiplying for decades, as is the case with immortalized lines, they will have acquired countless genetic changes. Add a synthetic, two-dimensional environment and you will select for cells that are more adept at growing within it. At the end of the day, you’re left with cells that are 50 years removed from the tumor and patient body they came from – cells that in fact may barely resemble a real-life tumor at all.

Architecture in cell culture really makes a functional difference for modeled tumor behavior and, thus, clinical outcomes. Cells cultured in 2D experience a uniform exposure to oxygen and nutrients rather than the more realistic gradients across different sites of tumor tissue. Also, due to a one-sided attachment to the dish in which they are grown, these cells lose their polarity –significant because the shift alters their response to key processes like programmed cell death.

As artificial interactions with the culture environment skews understanding in the wrong direction, other critical 3D interactions between cells and their natural environment (the TME) are lost completely: the unpredictable dance between cancer cells and healthy surrounding cells, structures, and signaling molecules that could inform therapeutic mechanisms. In more ways than one, 2D culture provides a flattened view of what really is a dynamic landscape from every angle and axis.

“Cancer cells are like seeds in soil: you must understand the soil to understand the cancer,” said Goka, whose lab focuses on colorectal cancers. “The seed doesn’t grow unless you have the optimal soil condition.”

Co-culture is something that would allow this “whole garden” view of the tumor in context. In co-culture, researchers have the opportunity to introduce additional cell types like fibroblasts or immune cells that would normally be present in the tumor microenvironment and that can impact how a tumor responds to drug treatment.

Co-culture is most informative in the 3D setting where it can help capture cell-cell interactions, but 3D spheroid models to date have required highly specialized materials and knowledge – unrealistic for many labs.

Tumoroid systems bring a biologically relevant model to drug discovery.

 The next-generation solution to many of these complex research barriers, including barriers to co-culture, could lie in a combination of more accessible three-dimensional models and personalized medicine. That solution is tumoroid systems.

Tumoroid culture systems combine the physiological accuracy of patient-derived cancer cells with the architectural accuracy of 3D interactions.

In a recent comparative analysis of response to treatments and molecular features of tumoroids versus cell lines and xenografts – all using patient-derived ovarian carcinoma cells – only tumoroid models presented as predictive tools capable of guiding therapeutic decision-making.

As important as being able to model a tumor in 3D culture is the ability to model the right tumor. That’s where patient-derived cells, a primary culture established directly from a patient’s tumor sample, come in.

One key advantage to using patient-derived cells is that, unlike immortalized cells that have racked up a half century’s worth of mutations into genomic instability, freshly harvested patient tumor cells maintain the most recent and relevant mutations specific to that (often treatment-resistant) tumor. And crucially, in a 3D tumoroid culture system with co-culture, a patient’s cancer cells has space in all directions to reform the complex structures it holds in the body. It’s intuitive how this kind of model would give the best shot at success for clinicians hoping to create a personalized treatment for a specific patient and their tumor(s).

“The [tumoroid] platform is another tool, perhaps a better tool, that we now have at our disposal,” said Goka. “With it we can ask some of the more complicated and more physiologically relevant questions about cancer treatment.”

Even for drug development with therapeutic reach beyond a single person, cells from patient-derived lines can be propagated with a kit like OncoPro medium to establish new, more relevant models than immortalized lines can provide. Researchers have tried establishing patient-derived lines in 2D in the past, but often found that samples experienced earlier senescence and/or large differences in gene expression compared to the original tumor.

This can be particularly important for expanding research into more representative patient populations.

“Say you have a biomarker that you’ve identified in colorectal cancer,” said Goka.“If you could then compile a panel of organoids that accurately reflect the patient population, you can investigate your hypothesis in those organic settings. And that would give you more faith, moving into your costly and time-consuming clinical trials, that your hypothesis may be valid.”

Likewise, researchers can specifically culture tumoroids that have in a clinical setting demonstrated resistance to first-line treatments but vulnerability to new therapies – a more accurate sandbox for drug testing.

Goka’s lab, for example, is interested in colorectal cancers that are resistant to platinum-based chemotherapies.

 

“We can use organoid models that are derived from patients who have already progressed on these therapies,” Goka said. “We can directly test our hypothesis on these models because we know that the patients were resistant to the standard of care chemotherapy, and we can confirm that the organoid models from those tumors are indeed resistant. We can then go on to test our drugs in that setting.”

For all of these reasons and perhaps more that we have yet to discover, tumoroid systems emerge as an unmatched, incredibly valuable tool in the field.

Up to 97% of cancer drug candidates fail in clinical trials. Tumoroid culture offers researchers a new way to test a hypothesis before taking a costly and time-consuming plunge that involves the lives of real patients.

“There are a number of really good drugs out there that are just not used properly, which is very unfortunate,” said Goka. This usually happens when researchers inadvertently test a drug against a less-than-ideal cancer model. “There are examples of drugs out there that will only work in certain types of cancer – say, breast cancer [for example]. And if researchers have better data, they may realize that the drug is more effective in breast cancer, and that would lead to a faster, more relevant approval.”

 

Staving off a reproducibility crisis in a promising field and saving time while doing it

Of course, tumoroid systems are not net-new. Scientists could already culture them with a DIY “homebrew” setup if they could spare the time, money, and patience. But OncoPro medium takes it a step further, streamlining an ideal setup for 3D tumoroid culture into a commercially available, “off-the-shelf” kit that promises to make this model of biologically-relevant cancer research more accessible and reproducible than ever.

 

Imagine twenty cooks all trying to create the same dish while making up their own recipes. Like this, certain academic research labs have spent years coming up with their own tumoroid culture systems, to varying degrees of non-standardized success. It takes a lot of time and knowledge to perfect, and the path to that success may not be obvious beyond the originating lab.

“Sometimes there’s a secret sauce, ingredients that aren’t disclosed,” Goka said. “In a home kitchen, some cooks might not be disclosing that they add allspice to their signature dish – though that’s why it tastes so good. Or that they bake it at 350 degrees and not 375 degrees, and that’s why it’s so moist. Seemingly subtle differences may not be so subtle when it comes to obtaining reproducible results.”

Just like your great aunt’s proprietary fruitcake recipe, tumoroid culture has long been discouragingly complex for many researchers.

An off-the-shelf kit changes the equation. “With the OncoPro system, Thermo Fisher has done the hard work,” Goka said.

A standard kit that works consistently across cancer indications benefits the cancer field as much as it does the individual scientist with a newly streamlined workflow.

“Standardization is really critical,” said Goka. “Now, every lab that grows tumoroids can use the same protocols. We can compare our data to confirm that the breakthroughs we’re making in the lab are consistent and reproducible.”

Standard models and streamlined procedures could also one day open the door for emerging personalized medicine applications, in which clinicians may leverage tumoroid systems for individual patients – much like autologous cell therapy, which is developed from same-patient donor cells.

For a patient who is running out of time, asking the right questions makes all the difference.

“Many cancer patients are running out of options, and their hope lies in the R&D that provides new and effective treatments,” Goka said. “By providing a better understanding of how new therapeutics are likely to perform in an in vitro setting, the OncoPro Tumoroid Medium System will help researchers like me to find the next generation of cancer treatments.”

Learn more at thermofisher.com/oncopro »

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Recommended Reading and Resources

 

Published Literature & Data:

• 2D versus 3D: 2D and 3D cell cultures – a comparison of different types of cancer cell cultures (Arch Med Sci. 2018)
• Tumoroid versus other models: Comparative analysis of response to treatments and molecular features of tumor-derived organoids versus cell lines and PDX derived from the same ovarian clear cell carcinoma.(J Exp Clin Cancer Res, 2023)
• Co-culture and tumor microenvironment (TME): Generation of tumor-reactive T cells by co-culture of peripheral blood lymphocytes and tumor organoids (Cell, 2018)
• OncoPro Tumoroid Medium System performance data (Thermo Fisher Scientific)

Learning Resources:

• Tumoroid Modeling Research Posters
• Tumoroid Learning Hub (eLearning courses, guidebooks, workflows, product suggestions)

  

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References

American Association for Cancer Research (AACR). How the Tumor Microenvironment Supports or Stifles Cancer Growth. AACR Meeting News. Accessed Nov 25, 2023. Available from: https://www.aacr.org/about-the-aacr/newsroom/aacr-meeting-news/how-the-tumor-microenvironment-supports-or-stifles-cancer-growth/

Jensen C, Yong T. Is It Time to Start Transitioning From 2D to 3D Cell Culture? Frontiers in Molecular Biosciences. 2020; Volume 7. Available from: https://www.frontiersin.org/articles/10.3389/fmolb.2020.00033/full

Murfin, K. What Is the Tumor Microenvironment? 3 Things to Know. MD Anderson Cancer Wise. Published Apr 6, 2021. Accessed Nov 25, 2023. Available from: https://www.mdanderson.org/cancerwise/what-is-the-tumor-microenvironment-3-things-to-know.h00-159460056.html

 

 

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