Liquid biopsies and tumor mutational burden: the cutoff conundrum
PM Kazi et al, Nature Medicine, September 12, 2022
One of the biggest advances in cancer care has been the advent of immunotherapy, and one of the biggest challenges is predicting which patients are most likely to benefit from it. Several predictive markers have been proposed, with the assessment of the quantity of mutations in a cancer (known as the tumor mutational burden, or TMB) being one of the most promising, particularly as it can be evaluated in the form of a noninvasive, blood-based ‘liquid biopsy’.
Assessment of tumor mutational burden through a simple blood test could help to identify which patients are most likely to benefit from immunotherapy, but optimal cutoffs are not well established.
cfDNA methylome profiling for detection and subtyping of small cell lung cancers.
Chemi Francesca et al. Nature cancer 2022 8
We describe a robust workflow for genome-wide DNA methylation profiling applied to both patient-derived models and to patients' circulating cell-free DNA (cfDNA). Tumor-specific methylation patterns were readily detected in cfDNA samples from patients with SCLC and were correlated with survival outcomes. cfDNA methylation also discriminated between the transcription factor SCLC subtypes, a precedent for a liquid biopsy cfDNA-methylation approach to molecularly subtype SCLC. Our data reveal the potential clinical utility of cfDNA methylation profiling as a universally applicable liquid biopsy approach for the sensitive detection, monitoring and molecular subtyping of patients with SCLC.
Circulating tumour DNA - looking beyond the blood.
Tivey Ann et al. Nature reviews. Clinical oncology 2022 8
To date, the majority of research in the area of liquid biopsies has focused on blood-based biomarkers, predominantly using plasma-derived circulating tumour DNA (ctDNA). However, ctDNA can also be obtained from various non-blood sources and these might offer unique advantages over plasma ctDNA. In this Review, we discuss advances in the analysis of ctDNA from non-blood sources, focusing on urine, cerebrospinal fluid, and pleural or peritoneal fluid, but also consider other sources of ctDNA.
Circulating tumor DNA to guide rechallenge with panitumumab in metastatic colorectal cancer: the phase 2 CHRONOS trial.
Sartore-Bianchi Andrea et al. Nature medicine 2022 8
The primary endpoint of the trial was met; and, of 27 enrolled patients, eight (30%) achieved partial response and 17 (63%) disease control, including two unconfirmed responses. These clinical results favorably compare with standard third-line treatments and show that interventional liquid biopsies can be effectively and safely exploited in a timely manner to guide anti-EGFR rechallenge therapy with panitumumab in patients with mCRC.