Marinac, Catherine R

Abstract Blood-based multicancer early detection (MCED) tests represent a new approach for cancer detection. To gain insights into the utility of various approaches of evaluating a cancer signal detected (CSD) test result, we evaluated diagnostic journeys of a subset of 6,662 participants in PATHFINDER who had a CSD on both an initial and refined version of an MCED test that also provided a prediction of cancer signal origin (CSO). We sought to determine whether CSO prediction–guided diagnostic evaluations led to diagnostic resolution; whether participants with known risk factors for cancer beyond age alone and a negative initial diagnostic evaluation had a cancer diagnosis during study follow-up; the utility of whole-body imaging in reaching diagnostic resolution; and differences in the diagnostic journeys needed to reach diagnostic resolution for both true- and false-positive results. Of the 39 participants in this analysis, 82% (32/39) achieved diagnostic resolution after the initial evaluation, including 78% (25/32) who reached resolution specifically with a CSO prediction–directed workup. Eighteen percent (7/39) required additional evaluation for persistent clinical suspicion of cancer, all of whom achieved resolution (3 with and 4 without cancer). Whole-body imaging contributed to diagnostic resolution in only 49% of CSD cases. Approximately 90% of true- and false-positive cases had imaging tests; more true positives versus false positives (81.0% vs. 38.9%) had nonsurgical and/or surgical procedures. In conclusion, CSO prediction–directed evaluations enabled diagnostic resolution for most participants, although some with negative initial evaluations but persistent suspicion of cancer required additional testing. Prevention Relevance: MCED testing has the potential to increase detection of cancer at earlier stages. As MCED testing is a new technology, there are few data on the diagnostic journeys patients undergo following testing. We observed that for most patients, CSO prediction–directed workups were efficient, leading to diagnostic resolution after initial evaluation.

Guideline-recommended screening programs exist for only a few cancer types. Although all these programs are understood to lead to reductions in cancer-related mortality, standard-of-care screening tests vary in accuracy, adherence and effectiveness. Recent advances in high-throughput technologies and machine learning have facilitated the development of blood-based multi-cancer cancer early detection (MCED) tests. MCED tests are positioned to be complementary to standard-of-care screening and they may broaden screening availability, especially for individuals who are not adherent with current screening programs and for individuals who may harbor cancers with no available screening options. In this article, we outline some key features that should be considered for study design and MCED test development, provide an example of the developmental pathway undertaken for an emerging multi-biomarker class MCED test and propose a clinical algorithm for an imaging-based diagnostic resolution strategy following MCED testing.

Summary: While the current approach to precursor hematologic conditions is to “watch and wait,” this may change with the development of therapies that are safe and extend survival or delay the onset of symptomatic disease. The goal of future therapies in precursor hematologic conditions is to improve survival and prevent or delay the development of symptomatic disease while maximizing safety. Clinical trial considerations in this field include identifying an appropriate at-risk population, safety assessments, dose selection, primary and secondary trial endpoints including surrogate endpoints, control arms, and quality-of-life metrics, all of which may enable more precise benefit–risk assessment.

To examine the extent of the evaluation required to achieve diagnostic resolution and the test performance characteristics of a targeted methylation cell-free DNA (cfDNA)-based multi-cancer early detection (MCED) test, ~6200 participants ≥50 years with (cohort A) or without (cohort B) ≥1 of 3 additional specific cancer risk factors will be enrolled in PATHFINDER (NCT04241796), a prospective, longitudinal, interventional, multi-center study. Plasma cfDNA from blood samples will be analyzed to detect abnormally methylated DNA associated with cancer (i.e., cancer “signal”) and a cancer signal origin (i.e., tissue of origin). Participants with a “signal detected” will undergo further diagnostic evaluation per guiding physician discretion; those with a “signal not detected” will be advised to continue guideline-recommended screening. The primary objective will be to assess the number and types of subsequent diagnostic tests needed for diagnostic resolution. Based on microsimulations (using estimates of cancer incidence and dwell times) of the typical risk profiles of anticipated participants, the median (95% CI) number of participants with a “signal detected” result is expected to be 106 (87–128). Subsequent diagnostic evaluation is expected to detect 52 (39–67) cancers. The positive predictive value of the MCED test is expected to be 49% (39–58%). PATHFINDER will evaluate the integration of a cfDNA-based MCED test into existing clinical cancer diagnostic pathways. The study design of PATHFINDER is described here.