Beyond Detection: The Value of qPCR in Clinical Practice and Research

Real-time PCR applications in molecular monitoring, biomarker analysis and biomedical research

Fast, sensitive and quantitative, real-time PCR (qPCR) remains an essential tool in biomedical laboratories. Its value goes beyond detecting a molecular alteration: qPCR can also quantify it and track how it changes over time, providing useful information for diagnosis, patient monitoring and research.

qPCR combines amplification of a specific target with real-time monitoring of the reaction. Its specificity, broad dynamic range and rapid turnaround continue to make it highly relevant alongside digital PCR (dPCR) and next-generation sequencing (NGS).

The key is to start with the right question. When the molecular target is already known and a fast, sensitive and reproducible analysis is required, qPCR is particularly effective. Broader profiling technologies are better suited to investigating large numbers of alterations or identifying unexpected variants. Rather than competing, these approaches are complementary.

qPCR in oncohaematology: measuring response, not just confirming diagnosis

One of the clearest examples of the clinical value of qPCR is molecular monitoring in chronic myeloid leukaemia (CML), which is characterised by the BCR::ABL1 fusion resulting from the t(9;22) translocation.

Once the transcript has been identified at diagnosis, serial quantification can be used to assess response to tyrosine kinase inhibitor therapy. It may also reveal changes in molecular burden before they become apparent through conventional haematological parameters.

For this reason, results should not be interpreted as isolated measurements. What matters is the trend across consecutive samples analysed under comparable conditions and with appropriately normalised results. For standard BCR::ABL1 transcripts, reporting on the International Scale (IS) supports comparison between laboratories and helps classify levels of molecular response.

The 2025 European LeukemiaNet (ELN) recommendations continue to emphasise the importance of identifying the transcript type at diagnosis. This is particularly relevant because atypical variants may not be detected or quantified accurately by assays designed for the most common transcripts.

The same principle applies to other haematological malignancies with defined molecular markers. In acute promyelocytic leukaemia, for example, monitoring PML::RARA can support the assessment of measurable residual disease and help identify molecular recurrence. Other fusions, mutations or rearrangements may also be monitored when they are informative for the individual patient and the assay has been validated for its intended clinical use.

Reliable clinical results depend on a controlled pre-analytical phase, appropriate controls, a validated reference gene, known assay sensitivity and participation in external quality assessment programmes.

qPCR in pathology: molecular information from tissue samples

In pathology, qPCR complements morphological assessment and immunohistochemistry by providing targeted molecular information.

It can be applied to biopsies, surgical specimens, cytology samples and formalin-fixed, paraffin-embedded (FFPE) material. Validated assays can be used to investigate specific mutations, fusion transcripts, amplifications, methylation changes or DNA from infectious agents associated with particular lesions.

In solid tumours, relevant targets may include alterations in genes such as EGFR, KRAS or BRAF. However, method selection should reflect the tumour type, current clinical recommendations and the number of biomarkers that need to be assessed. When a broad panel is required, NGS may be more efficient and make better use of limited tissue material.

FFPE samples present specific challenges. Fixation can fragment and chemically modify nucleic acids, while the proportion of tumour cells directly affects assay sensitivity. Pathology review, macro- or microdissection when appropriate, the use of short amplicons and prior assessment of DNA or RNA quantity and quality can therefore be critical.

A negative result can only be interpreted reliably when the sample is adequate and the assay’s limit of detection is compatible with the expected tumour fraction.

qPCR in research: a flexible platform for generating and validating knowledge

In research, qPCR can be used to quantify gene expression, validate transcriptomic findings, assess copy number, analyse selected variants and measure microbial abundance. It also enables efficient comparisons between experimental conditions, time points and treatments.

However, obtaining an amplification curve does not automatically mean that a result is valid. Experimental design should account for sample integrity, primer and probe specificity, amplification efficiency, linear range, contamination and reverse-transcription controls, as well as an appropriate normalisation strategy.

In gene expression studies, for example, relying on a single reference gene without first confirming its stability can introduce substantial bias.

The MIQE 2.0 guidelines, published in 2025, update recommendations for designing, evaluating, analysing and reporting qPCR experiments. Applying these principles improves transparency, reproducibility and comparability between laboratories. This becomes particularly important when an assay developed in a research setting is expected to progress towards a translational or clinical application.

qPCR, dPCR or NGS: choosing the technology that fits the question

qPCR is particularly effective when a limited number of known targets need to be analysed. dPCR can offer advantages for absolute quantification, very low-frequency variants or small differences in copy number. NGS, in turn, expands analytical capacity when multiple genes, fusions or variants need to be assessed in parallel.

The decision should not be driven by which technology is the newest. Instead, it should reflect the available sample, required sensitivity, number of targets, turnaround time and intended use of the result.

In clinical applications, validated methods, traceability and appropriate quality controls are also essential. Results should ultimately be interpreted alongside the other available clinical and laboratory findings.

From assay to result: the value of specialised qPCR support

Designing or implementing a qPCR workflow requires decisions at every stage, from sample preservation and preparation to nucleic acid extraction, detection chemistry, assay design, controls, data analysis and acceptance criteria.

Technical support from the outset can help anticipate limitations, optimise resources and generate more robust and reproducible results.

If you are developing or transferring a qPCR application into the laboratory, the Biomol team can help you assess the workflow and select the most appropriate solutions for your sample type and experimental objective.