Cancer treatment has evolved from one-size-fits-all chemotherapy and radiation to precision medicine, which aims to tailor drug treatment to individual patient needs. This can be achieved by testing various drugs on tumour samples isolated from the patient. Forty percent of cancer cases in India are related to head and neck cancer, and very few reports are available on developing personalised medicine solutions for oral cancer. Viraj Mehta, a shared first author of the study, a former PhD student and currently a scientist at Sai Life Sciences Ltd, points out,

We felt there was a need to tap the potential of organ-on-chips and precision medicine with respect to oral cancer, which is very appropriate in the Indian context.

The aim of the study was to develop a drug-screening platform that will enable researchers a better understanding of how drugs interact with cancer cells. Subha Narayan Rath, Professor at Indian Institute of Technology Hyderabad (IITH), and his group developed a new device based on the principle of microfluidics, that can simulate the dynamic flow of fluids in the body. 

The primary challenge in cancer treatment is the various subtypes of tumours and their ability to develop drug resistance, allowing them to survive chemotherapy. Therefore, instead of mono-drug therapies, using combinations of chemotherapy drugs can be beneficial.

The researchers found Formlabs clear resin to be the best 3D printing material for fabricating polydimethylsiloxane (PDMS) based spheroids-on-chip. The patented device features two layers consisting over a network of serpentine loops for mixing drug combinations, and arrays of cylindrical microwells for culturing patient-derived spheroids, and fluidic ports for interfacing with external pumps. The chip can test seven combinations of three anti-cancer drugs on patient-derived spheroids. 

Spheroids are self-aggregating cancer cells. They are more beneficial than normal 2D culture of tumor cells because ​“They help in replicating diverse tumour population and conditions present within the body like oxygen and pH gradient and various cell zones,” Mehta said. To further mimic the in vivo tumour microenvironment, spheroids on the device are maintained at oxygen levels less than 5% and remain viable for 5 days.

For the study, the research team enrolled three patients whose biopsy samples were used to isolate oral tumour stem-like cells. The derived cells were further cultured to form spheroids on the designed chip to test against drug combinations. Three commonly used chemotherapy drugs against oral cancer-paclitaxel, 5‑fluorouracil, and cisplatin-were tested on the patient-derived spheroids.

Researchers observed that spheroids formed from patients diagnosed with well-differentiated tumours exhibited high levels of E‑cadherin expression, indicating increased cell-cell contact. On the other hand, spheroids from moderately differentiated tumours showed significantly lower E‑cadherin expression. 

The variation among patient tumours was clearly observed as the spheroids of patient 1 showed high drug resistance against all provided combinations, whereas other patients responded well to certain combinations of drugs or even mono-drugs. Thus, researchers could identify most-effective drug combinations and drug resistances for each individual patient through simple fluorescence readout from the chip. 

However, the study did not include other cell types like fibroblasts, immune cells, and endothelial cells that affect drug responses. Also, pharmacokinetic profiling of spheroids, i.e how the drug is absorbed, distributed, metabolised, and excreted upon exposure was not included. In the future, the researchers plan to address these limitations and develop a more complex model for better reflection of the in vivo tumour microenvironment.

This is not the first time that combinatorial drug screening has been tested on 3D spheroids. However, ​“beauty of the work lies in combining patient samples, 3D tumoroids, and combinatorial testing of 3 clinically relevant drugs,” said Abhijit Majumder, Professor, IIT Bombay, an expert in the field and not associated with the study. He further added that,

The device can be used for other purposes also such as finding the hepatotoxicity of new drug molecules for combinatorial therapy.