Circulating DNA (ctDNA) Yes, again! A noninvasive method of diagnosing and monitoring melanoma patients

Yep.  Another thing I have been yelling about for years.  Circulating tumor DNA.  Something we can measure in the blood of melanoma patients.  Here are zillions of reports:  Important stuff floating in our blood - tumor DNA, micro RNA, cytokines - can determine tumor burden, predict response, and side effects for melanoma patients!!!  Now, there's this:

ctDNA as a noninvasive monitoring tool in metastatic melanoma.  2019 ASCO.  Varaljai, Wistuba-Hamprecht, Seremet, et al.  J Clin Oncology 37, 2019.

Background: The field of liquid biopsy provides a promising alternative to standard tissue biopsies. Previous work has shown that plasma circulating cell-free DNA (ctDNA) can reflect the heterogeneous spectrum of mutations in cancer including metastatic melanoma. Our project aimed to establish and statistically validate plasma-based assays for tumour load and therapy monitoring in melanoma. Methods: On a large cohort of stage III and stage IV melanoma patients (N = 96) who received signalling targeted or immune checkpoint inhibitors we showed that the most common oncogenic drivers of this disease such as the BRAFV600E, NRASQ61 and the TERTC250T and TERTC228T promoter mutations (termed TERTprom) can be analysed in ctDNA with highly sensitive droplet digital PCR technology (detection of mutant ctDNA down to 0.01% analytical sensitivity). Results: Our research has demonstrated that ctDNA (irrespective of the genotype) significantly correlates with tumour stage. Using receiver operating characteristics (ROC) analyses thresholds were established for risk stratification and response prediction. Elevated ctDNA at baseline was a significant predictor of disease progression compared to elevated LDH or S100 in multivariable cox proportional hazards model. During therapy, patients with low ctDNA load (below the ROC threshold) had significantly better radiological outcomes and prolonged progression free survival (PFS) compared to patients with high ctDNA load. Our findings were confirmed on an independent cohort of metastatic melanoma patients (N = 35) treated with immune checkpoint inhibitors, where also during therapy low ctDNA load correlated with prolonged PFS. An added benefit of ctDNA was demonstrated in about 80% of the patients, where ctDNA analyses preceded the radiological diagnosis of response or relapse. Progression was detected in plasma ctDNA in average 3.5 months earlier as compared to routine imaging techniques. Finally, we demonstrated that the occurrence of NRASQ61 mutation in BRAFV600-inhibitor treated patients at therapy baseline was associated with treatment failure. The sub-clonal NRASQ61 mutation at therapy baseline was an independent predictor of shorter PFS as compared to BRAFV600E patients without the NRASQ61 mutation at therapy baseline. Conclusions: In sum, our results support the value of ctDNA as a sensitive biomarker for real-time therapy monitoring and early detection of disease progression.

It works!  Doesn't require surgical biopsy.  Shows results months sooner than radiological imaging techniques and doesn't expose the patient to radiation.  What are we waiting on??????

There is also, this:

Circulating Cell-Free DNA-Diagnostic and Prognostic Applications in Personalized Cancer Therapy.  Oellerich, Schutz, Beck, Walson.  Ther Drug Monit. 2019 Apr.

Genomic analyses in oncologic care allow for the development of more precise clinical laboratory tests that will be critical for personalized pharmacotherapy. Traditional biopsy-based approaches are limited by the availability of sequential tissue specimens to detect resistance. Blood-based genomic profiling ("liquid biopsy") is useful for longitudinal monitoring of tumor genomes and can complement biopsies. Tumor-associated mutations can be identified in cell-free tumor DNA (ctDNA) from patient blood samples and used for monitoring disease activity. The US Food and Drug Administration approved a liquid biopsy test for EGFR-activating mutations in patients with non-small-cell lung cancer as a companion diagnostic for therapy selection. ctDNA also allows for the identification of mutations selected by treatment such as EGFR T790M in non-small-cell lung cancer. ctDNA can also detect mutations such as KRAS G12V in colorectal cancer and BRAF V600E/V600K in melanoma. Chromosomal aberration pattern analysis by low-coverage whole genome sequencing is a new, broader approach. Genomic imbalances detected in cell-free DNA (cfDNA) can be used to compute a copy number instability (CNI) score. In clinical studies, it was demonstrated that the change in CNI score can serve as an early predictor of therapeutic response to chemotherapy/immunotherapy of many cancer types. In multivariable models, it could be shown that the CNI score was superior to clinical parameters for prediction of overall survival in patients with head and neck cancer. There is emerging evidence for the clinical validity of ctDNA testing regarding identification of candidates for targeted therapies, prediction of therapeutic response, early detection of recurrence, resistance mutation detection, measuring genetic heterogeneity, tumor burden monitoring, and risk stratification. Improvement of sensitivity to detect tumors at very early stages is difficult due to insufficient mutant DNA fraction of less than/= to 0.01%. Further developments will include validation in prospective multicenter interventional outcome studies and the development of digital platforms to integrate diagnostic data.

The technology exists to make this simple test available - impacting melanoma patients in lots of ways!  Let's make it so!!!

And, yes.  There is still beauty -

 - despite the storm.  ~ les