Germline Cancer Predisposition Results From the National Cancer Institute-Children's Oncology Group Pediatric MATCH...

Precision oncology trials have generally focused on tumor testing to identify actionable alterations. The National Cancer Institute-Children's Oncology Group Pediatric MATCH trial incorporated return of germline results to assess feasibility of reporting in a cooperative group setting and characterize germline cancer predisposition in patients with refractory cancers.

Tumor and blood DNA from patients 1-21 years of age with treatment-refractory solid tumors, non-Hodgkin lymphomas, or histiocytic disorders underwent cancer gene panel sequencing. Clinical germline reports returned to 151 study sites included pathogenic/likely pathogenic (P/LP) germline variants found in 38 cancer predisposition genes (CPGs). European Society of Medical Oncology (ESMO) recommendations for germline follow-up of tumor variants in CPGs were assessed.

Both tumor and germline reports were completed for 1,167 patients (87.5% of enrolled). A total of 295 tumor reports (25%) included 361 CPG variants of which 70 variants (19.4%) were found in the germline sample. Three additional germline-only CPG variants resulted in 73 (6.3%) of 1,167 germline reports containing variants across 21 CPGs previously associated with pediatric and/or adult cancers. Among frequently mutated CPGs in tumors, concurrent germline findings ranged from 8/32 NF1 (25.0%) and 25/163 TP53 (15.3%) to zero of 27 ALK and 18 PTEN tumor variants. ESMO guidelines recommended clinical follow-up for 110 (30.5%) of 361 tumor CPG variants which included 40 (57.1%) of 70 germline variants.

Coordinated germline and tumor panel testing was feasible and revealed P/LP CPG variants in 6.3% of the Pediatric MATCH cohort. Tumor variant fraction, germline association of CPG with tumor type, and adult-oriented guidelines were not predictive of germline status, emphasizing the need for systematic germline follow-up after tumor genomic testing for pediatric patients.