Cancer incidence and surveillance strategies in individuals with RASopathies

Update on Pediatric Cancer Surveillance Recommendations for Patients with Neurofibromatosis Type 1, Noonan Syndrome, CBL Syndrome, Costello Syndrome, and Related RASopathies

Neurofibromatosis type 1 (NF1), Noonan syndrome, and related syndromes, grouped as RASopathies, result from dysregulation of the RAS-MAPK pathway and demonstrate varied multisystemic clinical phenotypes. Together, RASopathies are among the more prevalent genetic cancer predisposition syndromes and require nuanced clinical management. When compared with the general population, children with RASopathies are at significantly increased risk of benign and malignant neoplasms. In the past decade, clinical trials have shown that targeted therapies can improve outcomes for low-grade and benign neoplastic lesions but have their own challenges, highlighting the multidisciplinary care needed for such individuals, specifically those with NF1. This perspective, which originated from the 2023 American Association for Cancer Research Childhood Cancer Predisposition Workshop, serves to update pediatric oncologists, neurologists, geneticists, counselors, and other health care professionals on revised diagnostic criteria, review previously published surveillance guidelines, and harmonize updated surveillance recommendations for patients with NF1 or RASopathies.

Genomic ascertainment to quantify prevalence and cancer risk in adults with pathogenic and likely pathogenic germline variants in RASopathy genes

Purpose

Genomic ascertainment of electronic health record-linked exome data in two large biobanks was used to quantify germline pathogenic/likely pathogenic (P/LP) variant prevalence, cancer prevalence, and survival in adults with non-NF1 RAS/mitogen-activated protein kinase genes (RASopathies).

Patients and Methods

Germline RASopathy variants were examined from adult participants in UK Biobank (UKBB; n=469,802), Geisinger MyCode (n=167,050) and Mount Sinai BioMe (n=30,470). Variants were classified as per American College of Medical Genetics/Association for Molecular Pathology criteria and reviewed by a RASopathy variant expert. Heterozygotes harbored a RASopathy pathogenic/likely pathogenic variant; controls harbored wild type or benign/likely benign RASopathy variation. To distinguish germline variants from clonal hematopoiesis, benign tissues were Sanger sequenced. Tumor phenotype and demographic data were retrieved from MyCode and UKBB.

Results

Pathogenic variants in Noonan syndrome-associated genes (excluding known Noonan syndrome with multiple lentigines variants) were the most common with an estimated prevalence that ranged between 1:1,772-1:3,330 in the three cohorts. Pathogenic variants in cardiofaciocutaneous syndrome-associated genes had an estimated prevalence of 1:41,762-1:55,683 in two cohorts. Pathogenic variants in SPRED1 (Legius syndrome) were more frequent in UKBB (1:19,567 [95%CI: 1:13,150-1:29,116]) compared to MyCode (1:41,762 [95%CI: 1:15,185-1:130,367]). In SPRED1-heterozygotes, cancer prevalence was significantly increased in UKBB (OR:3.8 [95% CI: 2.48-8.64]; p=1.2×10-3) but not in the MyCode cohort. Pathogenic variants in HRAS (Costello syndrome) were not identified. In MyCode and UKBB cohorts, there was no significant increase in cancer prevalence in individuals with Noonan-, CBL- and CFC syndrome-associated pathogenic variants.

Conclusion

Genomic ascertainment from two large biobanks did not show evidence of elevated cancer risk in adult Noonan syndrome heterozygotes. There may be an increased cancer risk for adult SPRED1 heterozygotes.

Parenting Stress Index in Caregivers of Individuals With Noonan Syndrome

Medical professionals frequently underestimate stress level of parents/caregivers of patients with rare disorders as RASopathies, the latter might experience elevated stress levels, with their own health frequently overlooked despite significant responsibilities and hurdles encountered. The aim of this study is to assess the stress experienced by parents of individuals with Noonan syndrome and related conditions. Forty-eight parents (20 fathers; 28 mothers), among the 31 recruited families, completed the Italian version of the Parenting Stress Index-Short Form. Our study shows abnormally elevated scores (≥ 85° percentile) in 35.4% of parents. Data retrieved from subscales reveal a perception of a difficult child in 25% of cases, a dysfunctional parental-child interaction in 20.8%, a general parental distress in 10.4% of cases, and an elevated overall stress in 18.8% of parents. Questionnaires as the Parenting Stress Index-Short Form are valuable tools to evaluate stress in parents/caregivers of children with RASopathies. Evaluation by professionals is fundamental to support parents and caregivers in managing stressors and to enhance their quality of life and relationships. To prevent stress escalation and parents' burnout, an early assessment to tailor a timely treatment should be introduced as soon as possible as good clinical practice.

Childhood growth hormone treatment: challenges, opportunities, and considerations

With long standing demand and popularity, growth hormone treatments continue to be a topic of interest for paediatric endocrinologists and general paediatricians due to ongoing issues regarding their long-term effects, the safety of childhood treatment, and the introduction of long-acting growth hormone preparations in the past decade. Moreover, uncertainty regarding how to approach individual patients and their treatment indications remains, particularly concerning tailored treatment goals and objectives; this uncertainty is further complicated by the multitude of approved indications that surpass substitution therapy. The paediatric endocrinologist thus grapples with pertinent questions, such as what defines reasonable treatment goals for each individual given their indications, and when (and how) to initiate the necessary discussions about risks and benefits with patients and their families. The aim of this Review is to offer advanced physiological concepts of growth hormone function, map out approved paediatric indications for treatment along with evidence on their effects and safety, highlight controversies and complexities surrounding childhood growth hormone treatment, and discuss the potential of long-acting growth hormone and future directions in the realm of childhood growth hormone treatment.

The landscape of rare genetic variants in familial Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare hematological malignancy. Risk for WM is elevated 20-fold among first-degree relatives of patients with WM. However, the list of variants and genes that cause WM remains incomplete. In this study we analyzed exomes from 64 WM pedigrees for evidence of genetic susceptibility for this malignancy. We determined the frequency of pathogenic (P) or likely pathogenic (LP) variants among patients with WM; performed variant- and gene-level association analyses with the set of 166 WM cases and 681 unaffected controls; and examined the segregation pattern of deleterious variants among affected members in each pedigree. We identified P/LP variants in TREX1 and SAMHD1 (genes that function at the interface between innate immune response, genotoxic surveillance, and DNA repair) segregating in patients with WM from 2 pedigrees. There were additional P/LP variants in cancer-predisposing genes (eg, POT1, RECQL4, PTPN11, PMS2). In variant- and gene-level analyses, no associations were statistically significant after multiple testing correction. On a pathway level, we observed involvement of genes that play a role in telomere maintenance (q-value = 0.02), regulation of innate immune response (q-value = 0.05), and DNA repair (q-value = 0.08). Affected members of each pedigree shared multiple deleterious variants (median, n = 18), but the overlap between the families was modest. In summary, P/LP variants in highly penetrant genes constitute a modest proportion of the deleterious variants; each pedigree is largely unique in its genetic architecture, and multiple genes are likely involved in the etiology of WM.

RASopathies: Evolving Concepts in Pathogenetics, Clinical Features, and Management

RASopathies refers to the group of disorders which are caused by a mutation in various genes of the RAS/MAPK (RAT sarcoma virus/Mitogen activated protein kinase) pathway. It includes many genes with varied functions, which are responsible for cell cycle regulation. As the mutation in one gene affects the entire pathway, there are many overlapping features among the various syndromes which are included under an umbrella term "RASopathies." However, neuroectodermal involvement is a unifying feature among these syndromes, which are caused by germline mutations affecting genes along this pathway. Recently, many other RASopathies have been described to involve blood vessels, lymphatics, and immune system. Also, many cutaneous mosaic disorders have been found to have mutations in the concerned pathway. The purpose of this article is to briefly review the pathogenesis of RASopathies with cutaneous manifestations, and summarise the features that can be helpful as diagnostic clues to dermatologists. As we understand more about the pathogenesis of the pathway at the cellular level, the research on genotype-phenotype correlation and therapeutic options broadens. Targeted therapy is in the clinical and preclinical trial phase, which may brighten the future of many patients.

Cell phenotypes can be predicted from propensities of protein conformations

Proteins exist as dynamic conformational ensembles. Here we suggest that the propensities of the conformations can be predictors of cell function. The conformational states that the molecules preferentially visit can be viewed as phenotypic determinants, and their mutations work by altering the relative propensities, thus the cell phenotype. Our examples include (i) inactive state variants harboring cancer driver mutations that present active state-like conformational features, as in K-Ras4BG12V compared to other K-Ras4BG12X mutations; (ii) mutants of the same protein presenting vastly different phenotypic and clinical profiles: cancer and neurodevelopmental disorders; (iii) alterations in the occupancies of the conformational (sub)states influencing enzyme reactivity. Thus, protein conformational propensities can determine cell fate. They can also suggest the allosteric drugs efficiency.

The Cardiofaciocutaneous Syndrome: From Genetics to Prognostic-Therapeutic Implications

Cardiofaciocutaneous (CFC) syndrome is one of the rarest RASopathies characterized by multiple congenital ectodermal, cardiac and craniofacial abnormalities with a mild to severe ocular, gastrointestinal and neurological involvement. It is an autosomal dominant syndrome, with complete penetrance, caused by heterozygous pathogenic variants in the genes BRAF, MAP2K1/MEK1, MAP2K2/MEK2, KRAS or, rarely, YWHAZ, all part of the RAS-MAPK pathway. This pathway is a signal transduction cascade that plays a crucial role in normal cellular processes such as cell growth, proliferation, differentiation, survival, metabolism and migration. CFC syndrome overlaps with Noonan syndrome, Costello syndrome, neurofibromatosis type 1 and Legius syndrome, therefore making the diagnosis challenging. Neurological involvement in CFC is more severe than in other RASopathies. Phenotypic variability in CFC patients is related to the specific gene affected, without a recognized genotype-phenotype correlation for distinct pathogenic variants. Currently, there is no specific treatment for CFC syndrome. Encouraging zebrafish model system studies suggested that, in the future, MEK inhibitors could be a suitable treatment of progressive phenotypes of CFC in children. A multidisciplinary care is necessary for appropriate medical management.

SHP2: A Pleiotropic Target at the Interface of Cancer and Its Microenvironment

The protein phosphatase SHP2/PTPN11 has been reported to be a key modulator of proliferative pathways in a wide range of malignancies. Intriguingly, SHP2 has also been described as a critical regulator of the tumor microenvironment. Based on this evidence SHP2 is considered a multifaceted target in cancer, spurring the notion that the development of direct inhibitors of SHP2 would provide the twofold benefit of tumor intrinsic and extrinsic inhibition. In this review, we will discuss the role of SHP2 in cancer and the tumor microenvironment, and the clinical strategies in which SHP2 inhibitors are leveraged as combination agents to improve therapeutic response.

SIGNIFICANCE

The SHP2 phosphatase functions as a pleiotropic factor, and its inhibition not only hinders tumor growth but also reshapes the tumor microenvironment. Although their single-agent activity may be limited, SHP2 inhibitors hold the potential of being key combination agents to enhance the depth and the durability of tumor response to therapy.