A systematic review of the prevalence of pathogenic or likely pathogenic germline variants in individuals with FOXO1 fusion-positive rhabdomyosarcoma.

Several cancer predisposition syndromes (CPS) are reported to predispose to rhabdomyosarcoma, most frequently in children with embryonal rhabdomyosarcoma. There are lingering questions over the role of CPS in individuals with alveolar rhabdomyosarcoma (ARMS), which are frequently driven by FOXO1 fusion oncoproteins. We conducted a systematic review to identify patients with FOXO1 fusion-positive ARMS (FP-ARMS) who underwent germline DNA sequencing. We estimated the prevalence of pathogenic/likely pathogenic (P/LP) variants in cancer predisposing genes (CPGs) and of CPSs. We included 19 publications reporting on 191 patients with FP-ARMS. P/LP variants in CPGs were identified in 26/191 (13.6%) patients, nine (4.9%) of which were associated with a CPS diagnosis. Evidence for causal associations between CPSs and FP-ARMS could not be assessed with available data from this review. Only one patient was affected with a CPS known to predispose to rhabdomyosarcoma, Li-Fraumeni syndrome. Typical CPS associations with rhabdomyosarcoma are rare, but not nonexistent, in patients with FP-ARMS. FOXO1 fusion status, alone, is insufficient for clinicians to rely on to distinguish between patients with/without CPS.

Multicenter real-world experience of the clinical efficacy and tolerance of pazopanib in high-risk pediatric solid tumors (PazoPed).

Pazopanib, a receptor tyrosine kinase inhibitor, exhibits anti-tumor activity in adult bone and soft-tissue sarcomas (STS), but has not yet been approved for pediatric tumors. The primary objective was to evaluate pazopanib efficacy when used alone or in combination with topotecan. This real-world multicenter retrospective study included patients with solid tumors, aged 25 years or less at the time of initial diagnosis, treated with pazopanib outside of a clinical trial. Nineteen patients were eligible for efficacy analysis: 14 bone tumors and 5 STS. At pazopanib initiation, the median age was 16.9 years, 18 patients had metastatic disease with a median of 2 prior therapeutic lines. With 6.2 months of median follow-up, no objective response was observed, but 10 patients (52.6%) had stable disease at 8 weeks and the 6-month disease control rate was 26.3%. The median progression free (PFS) and overall survival (OS) were 3.0 months and 6.2 months, respectively. Multivariate analysis showed an inverse relationship between the number of prior treatment lines and PFS and OS (hazard ratio = 1.73 (p = 0.04) and 1.76 (p = 0.03), respectively). Our study showed a potential tumor control activity of pazopanib in pediatric bone and soft tissue sarcomas. Further studies are warranted to determine the optimal timing and condition for pazopanib introduction to maximize the effect.

Germline p.R181H variant in TP53 in a family exemplifying the genotype-phenotype correlations in Li-Fraumeni syndrome.

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with germline pathogenic/likely pathogenic variants in TP53. Genotype-phenotype correlations are progressively being characterized in LFS with certain TP53 variants associated with attenuated penetrance and phenotypes. We report on a family harboring a TP53 p.R181H variant presenting with a restricted cancer phenotype in adulthood. The proband was a female with breast cancer at the age of 71 years who had three first degree relatives also diagnosed with breast cancer after the age of 40 years (mother, two sisters). Of the nine individuals harboring the variant (6 genetically confirmed, 3 obligate heterozygous), six have not developed malignancies at this time (age range: 36-42). No childhood-onset cancers were reported in this family. A concomitant literature review identified 51 additional individuals harboring the p.R181H variant in TP53, presenting a tumor phenotype dominated by breast cancer. Rare occurrences of other adult-onset cancers (prostate, colorectal and thyroid) and only few childhood onset cancer were documented. These observations are consistent with functional analysis showing that p.R181H retains partial p53 function and suggesting possible reduced cancer penetrance, particularly in the pediatric setting.