Protein Drugs

Drug Targets


Gene Therapy

Longitudinal Studies


SISCAPA® technology solves challenging protein measurement problems encountered in drug development, clinical trials and diagnostics.

By combining the power of mass spectrometry and specific antibody recognition, SISCAPA assays offer unprecedented precision, sensitivity, and specificity without the limitations of conventional immunoassays and LBA’s: cross-reactivity, limited multiplexing, and sample interferences.

Our optimized assay development pipeline provides a predictable path to deployable assays for client-identified proteins and their variants.   Our automated, general-purpose SISCAPA workflow enables interference-free multiplexing of new assays with an existing SISCAPA menu covering clinically-established protein targets and biomarkers, and efficient transfer of assays and panels to clients and their CROs.

We have solved many difficult protein measurement challenges for pharma and diagnostic partners over the last 10 years. Among many examples these include:

  • assays to measure in vivo products of gene therapy
  • measurement of proteins with and without PTMs
  • measurement of insoluble and transmembrane proteins
  • measurement of ligand-binding and auto-antigenic proteins

Whether you are in the early stages of drug discovery, conducting preclinical studies, conducting clinical trials, or looking towards companion diagnostics, SISCAPA technology delivers accurate and reliable data that can inform critical decisions at every step of the pipeline.

Contact us about SISCAPA Assay Development Services

  • Peptide selection
  • Immuno-affinity reagent development and supply
  • Automated assay optimization & qualification
  • Implementation in serum, DBS, tissue and other matrices
  • Transfer to regulated CRO’s

Contact us about CRO Analytical Services


  • Non-GLP sample analysis
  • Multiplex panels combining novel and catalog assays
  • Longitudinal dried blood spot studies
Protein Drugs

Leveraging the power of SISCAPA technology, we offer accurate and quantitative measurement of therapeutic drugs, including antibodies and antibody-drug conjugates (ADCs). By precisely quantifying total drug concentrations, free vs bound ratios, and levels of anti-drug antibodies, we enable researchers and pharmaceutical companies to gain critical insights into drug efficacy, pharmacokinetics (PK), and pharmacodynamics (PD).

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SISCAPA technology enables definitive measurement of therapeutic mAbs. In one example a 24 amino acid long tryptic peptide derived from the heavy chain CDR2 region of an IgG1 therapeutic antibody was measured indigested human sera. “When compared with conventional ligand (protein) binding assays, MS assays often show shorter development times, fewer requirements for critical reagents, higher selectivity and unequivocal analyte identification. In addition, assays such as MRM analysis of peptides from trypsin-digested sera or plasma and especially SISCAPA assays that enrich surrogate peptides from such digests, eliminate many of the potential interferences caused by antibodies to the analyte or by other interfering proteins”.

SISCAPA assay for a therapeutic mAb

Development of an automated, interference-free, 2D-LC-MS/MS assay for quantification of a therapeutic mAb in human sera, F. K. Sucharski et al.,Bioanalysis, p. 9, Jul. 2018, doi: 10.4155/bio-2017-0252.

Contact us to discuss making a gold standard assay for your protein therapeutic.

Drug Targets

Understanding target concentrations, distribution and modulation by disease and treatment are crucial for the development and validation of novel therapeutics. Our SISCAPA platform provides a targeted and precise approach for measuring drug targets, both free and bound, enabling researchers to investigate target engagement, monitor target expression levels, and evaluate the impact of drugs on specific disease pathways.

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Drug targets are often challenging to measure accurately due to low abundance, physical properties (e.g., transmembrane location) or specific modifications (e.g., PTM’s). SISCAPA technology is effective in measuring proteins that are notoriously challenging to quantitate using other methods. An example of this is the case of NAV1.7 (SCN9a) and NAV1.9 (SCN10a). These two proteins belong to the voltage-gated sodium channel family and play crucial roles in pain sensation. Due to their membrane-bound nature and low abundance in complex biological samples (e.g. dorsal root ganglia), accurately quantifying NAV1.7 and NAV1.9 has posed a significant challenge.

The ability of SISCAPA to accurately measure proteins with transmembrane domains like NAV1.7 and NAV1.9 provides researchers with crucial insights into pain pathways, drug target validation, and therapeutic interventions. It allows for a deeper understanding of pain mechanisms and the development of more targeted and effective pain management strategies.

SISCAPA assay for sodium channel proteins

Contact us to discuss making a gold standard assay for your specific drug target.


Protein biomarkers play a vital role in diagnosing disease, monitoring treatment response, and predicting patient outcomes. SISCAPA technology provides accurate and reliable measurement of a broad range of protein biomarkers, individually and in panels, in a variety of matrices, allowing researchers and clinicians to uncover valuable insights into disease progression and treatment efficacy. Our solutions enable the validation of novel biomarkers and facilitate the development of diagnostic and prognostic tools for precision medicine.

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Over 350 SISCAPA assays have been developed against diverse protein biomarkers.

A prime example is thyroglobulin, a biomarker extensively used in monitoring reoccurance of thyroid cancer. SISCAPA’s unique approach circumvents assay interferences caused by autoantibodies, a common problem faced by immunoassays. By specifically targeting peptides derived from thyroglobulin after tryptic digestion, SISCAPA provides specificity and sub-ng/mL sensitivity in the presence of interfering autoantibodies. The resulting clinical test has provided precise results on hundreds of thousands of clinical samples, leading to improved patient care and outcomes.

SISCAPA assay for Thyroglobulin
A distributable LC-MS/MS method for the measurement of serum thyroglobulin., J. Shi, et al, Journal of Mass Spectrometry and Advances in the Clinical Lab, 28–33 (2022). DOI: 10.1016/j.jmsacl.2022.09.005
– download PDF

Contact us to discuss making a gold standard assay for biomarker.

Gene Therapy

Gene therapy has emerged as a promising approach for treating a range of inherited disorders. The SISCAPA platform enables researchers to precisely measure proteins resulting from expression of therapeutic gene constructs and distinguish these from endogenous defective molecules. Proteins of therapeutic vectors (e.g., AAV constructs) can also be measured.  The technology enables cross-species analysis of gene therapy constructs and their effects using a single assay, further facilitating pre-clinical and clinical studies. This valuable information helps assess gene delivery efficiency, evaluate treatment response, and optimize gene therapy protocols, ultimately advancing the field of gene-based therapeutics.

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SISCAPA technology offers a powerful approach for assessing gene therapy products and distinguishing them from endogenous counterparts.

In the case of dystrophin, a protein crucial for muscle function and lacking in Duchenne muscular dystrophe (DMD), gene therapy aims to restore its expression in individuals with genetic mutations. SISCAPA technology enables specific measurement of dystrophin protein forms in muscle samples, providing a valuable tool for evaluating the efficacy of gene therapy treatments and monitoring the restoration of dystrophin levels in preclinical and clinical studies.

Dystrophin and mini-dystrophin quantification by mass spectrometry in skeletal muscle for gene therapy development in Duchenne muscular dystrophy. V. Farrokhi, et al., Gene Ther (2021), doi:10.1038/s41434-021-00300-7.

Contact us to discuss making a gold standard assay for your specific gene therapy product.

Longitudinal Studies

SISCAPA empowers researchers to conduct longitudinal studies using dried blood spots (DBS), providing a non-invasive and convenient sample collection method. Combined with cutting-edge mobile health components and wearable sensors, we capture contextual data such as heart rate variability, blood pressure, and more. This integration allows for a comprehensive understanding of the relationship between biomarkers and physiological parameters over time, enabling researchers to unravel complex disease dynamics and optimize treatment strategies.

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The SISCAPA platform, Longitude DX, revolutionizes longitudinal measurement of protein biomarkers using dried blood spots (DBS). With its proprietary techniques and innovative technology, LongitudeDX® enables researchers to accurately monitor endogenous and synthetic proteins in blood over time. This ground-breaking capability provides unparalleled insights into disease dynamics and treatment efficacy.

Click here to explore LongitudeDX®


Contact us to discuss implementation and analysis of high-frequency dried blood sampling.