Draft:Functional drug sensitivity testing
Functional drug sensitivity testing (f-DST)
Overview
Functional drug sensitivity testing (f-DST) is an in-vitro diagnostic test method in functional precision medicine [1] developed to personalize the choice among cytotoxic drugs and drug combinations for patients with an indication for systemic chemotherapy in specific cancer types. [2] [3] [4]
f-DST is performed by various in-vitro diagnostic methods which have in common to quantify reactions of individual patient-derived cancer tissue when exposed to cytotoxic drugs.
As substrate, testing methods initially require live cancer tissue from an individual patient (metastases or primary tumor).
In the laboratory, bioptic samples containing live cancer tissue are processed to obtain the required type, histologic organization and number of carcinomatous cells, ie. isolated cells, or cell clusters of defined sizes.
The processed cancer specimen, cell or organized cell aggregates, are then cultured in stem cell media to increase in number and expand into a sufficient number of testable cancer cell aggregates as required, depending on the used test model.
After defined time periods of culture, often between 3 and 7 days, cell or organized cell aggregates are counted and transferred to drug screening arrays, where they are exposed to defined concentrations of the cytotoxic drugs or drug combinations in question.
Measurement methods and statistical analyses usually focus on cell/cell aggregate behaviour in vitro under exposure to the test drugs after defined periods of time.
Results from f-DST are surrogates for in vitro reactions of patient-derived cancer cell or cell aggregates following exposure to standardized cytotoxic drug concentrations over a specified time, relative to positive and negative controls and/or to calibration curves obtained from reference populations.
Background and Rationale
Cytotoxic sytemic chemotherapies are generally considered effective across larger patient populations on average [5], but are known to come with different side effect profiles. Therapeutic choices are currently based on the individual patient's overall medical situation and potential side effect tolerability. However, individual responses to systemic chemotherapy can vary due to differences in tumor biology, genetic makeup, and other factors. [6] This variability can affect the therapeutic risk/benefit ratio.
Methodology
Functional drug sensitivity testing involves methods to cultivate cancer cells obtained from a patient's tumor biopsy or surgical specimen.
Samples are processed eg. by mechanically mincing, enzymatically digesting the sample, and subsequent separation into fractions using a cell strainer.[7]
In the laboratory, cells, cell clusters, organoids, or tumoroids are isolated, cultured and then exposed to select cytotoxic agents like 5-FU, oxaliplatin, and irinotecan, individually or in combinations [8].
Sample Collection
A biopsy from the primary tumor or its metastases (eg. liver metastases), is collected by endoscopic, surgical or fine needle biopsy and sent to specialized laboratories. The biopsy / specimen shall contain living tumor tissue and must not be frozen or exposed to tissue fixatives like formalin. The samples are transported in tissue preserving buffers usually under controlled temperature conditions within eg. 24 hours to specialized laboratories to ensure survival of the live cancer tissue.
Laboratory procedures
Pre-analytical processing comprises tissue sample mincing, enzymatic digestion, selection and subsequent culture under controlled conditions. The cultured cells /cell clusters are then exposed to cytotoxic agents, including 5-FU, oxaliplatin, irinotecan, as well as to positive and negative controls (eg. sodium chloride; staurosporin).
Response Assessment
fDST response can be expressed as cell or cell aggregate weight changes, cell apoptosis signals, morphological changes, growth behaviour, growth area reduction and further parameters.
Data Analysis: Results are analyzed to identify the most effective drugs or combinations against the patient's cancer cells, compared to a reference dataset.
Clinical Application
f-DST provides information on an individual patient's tumor cell / cell cluster vulnerabilities towards cytotoxic chemotherapies in vitro [9].
Limitations and Future Directions
Submitting cancerous tissue for f-DST often requires additional biopsies as compared to the routine diagnostic workup of cancer patients. Shipping live bioptic tissue samples to specialized laboratories qualified to perform f-DST requires logistic planning.
The actual test exposing cells/cell cluster derivates needs to unfold over up to 7 days; final reports can mostly be available from between 14 to 21 days after sample reception.
Like other functional testing methods (e.g. antibiograms), none of the current f-DST methods aims to fully replicate the intricate interactions of tumor tissue within a patient's body. Information obtained by f-DST can be clinically helpful to choose among approved medication the cytotoxic drug or drug combinations with the most important cancer tissue growth impairment.
f-DST is an emerging in vitro diagnostic tool. It has the potential to shift the current average cytotoxic drug efficacy / side effects risk balance of systemic chemotherapies.
- ^ Letai, A (Jan 10, 2021). "Functional precision oncology: Testing tumors with drugs to identify vulnerabilities and novel combinations". Cancer Cell. 40. doi:10.1016/j.ccell.2021.12.004.
- ^ Letai, A (2022). "Functional Precision Medicine: Putting Drugs on Patient Cancer Cells and Seeing What Happens". Cancer Discov. 12 (2): 290–292. doi:10.1158/2159-8290.CD-21-1498.
- ^ Sakshaug, Christoffer (2023). "Systematic revew: predictive value of organoids in colorectal cancer". Scientific Reports. 13: 18124. doi:10.1038/s41598-023-45297-8.
- ^ Bouquerel, Charlotte (2023). "Bridging the gap between tumor-on-chip and clinics: a systematic review of 15 years of studies". The Royal Society of Chemistry. doi:10.1039/d3lc00531c.
- ^ Cervantes, A (2023). "Metastatic colorectal cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up". Annals of Oncology. 34 (1): 10–34. doi:10.1016/j.annonc.2022.10.003.
- ^ Cremolini, C (2020). "Upfront FOLFOXIRI plus bevacizumab and reintroduction after progression versus mFOLFOX6 plus bevacizumab followed by FOLFIRI plus bevacizumab in the treatment of patients with metastatic colorectal cancer". Lancet Oncol. 21: 497–507.
- ^ Kondo, Jumpei (March 28, 2011). "Retaining cell–cell contact enables preparation and culture of spheroids composed of pure primary cancer cells from colorectal cancer". PNAS. 108 (15): 6235–6240. doi:doi.org/10.1073/pnas.1015938108.
{{cite journal}}:|access-date=requires|url=(help); Check|doi=value (help); Check date values in:|access-date=(help) - ^ Jensen, Lars Henrik (2023). "Precision medicine applied to metastatic colorectal cancer using tumor-derived organoids and in-vitro sensitivity testing". Journal of Experimental & Clinical Cancer Research. 42 (115). doi:10.1186/s13046-023-02683-4.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Ulukaya, Engin (19 JUN 2021). "Tumor Chemosensitivity Assays Are Helpful for Personalized Cytotoxic Treatments in Cancer Patients". Medicina (Kaunas). 57 (6): 636. doi:10.3390/medicina57060636.
{{cite journal}}: Check date values in:|date=(help)CS1 maint: unflagged free DOI (link)