How we treat medulloblastoma in adults.

Medulloblastoma is a rare tumour in postpubertal patients and adults that is potentially curable. Several subgroups have been defined that are associated with clinical features, have different prognoses, and in some cases offer personalized treatment options. In adults, the sonic hedgehog (SHH) subtype is the most common subtype, followed by the wingless (WNT) and group 4 subtypes. Multimodal therapies allow 5-year overall survival rates of up to 70%. However, in adults, therapeutic evidence from prospective randomized trials is largely lacking. Therefore, regardless of individual risk, most patients are currently treated uniformly with craniospinal chemoradiation with a boost to the tumour bed, followed by maintenance chemotherapy, usually with alkylating agents. In Europe, the so-called Packer regimen, together with cisplatin-etoposide regimens, is the most commonly used chemotherapy option. Targeted treatment approaches have not yet been implemented, although tumour biology is well understood and offers personalized approaches, especially for the SHH subgroup. At relapse, rapid resistance occurs frequently, necessitating repositioning of these agents in an earlier treatment phase. Due to the good to intermediate prognosis, patients with medulloblastoma require structured long-term clinical follow-up including MRI of the brain, monitoring of side effects, and psychosocial and fertility counselling. Recently, clinical trials have been initiated with the aim of de-escalating treatment to reduce toxicity and adding targeted therapies to increase efficacy, with the main goal of therapy to cure the tumour while maintaining the physical and psychosocial integrity of affected patients. This article summarizes our opinion on the diagnosis and treatment of medulloblastoma in adults.

Current recommendations for clinical surveillance and genetic testing in rhabdoid tumor predisposition: a report from the SIOPE Host Genome Working Group.

The rhabdoid tumor (RT) predisposition syndromes 1 and 2 (RTPS1 and 2) are rare genetic conditions rendering young children vulnerable to an increased risk of RT, malignant neoplasms affecting the kidney, miscellaneous soft-part tissues, the liver and the central nervous system (Atypical Teratoid Rhabdoid Tumors, ATRT). Both, RTPS1&2 are due to pathogenic variants (PV) in genes encoding constituents of the BAF chromatin remodeling complex, i.e. SMARCB1 (RTPS1) and SMARCA4 (RTPS2). In contrast to other genetic disorders related to PVs in SMARCB1 and SMARCA4 such as Coffin-Siris Syndrome, RTPS1&2 are characterized by a predominance of truncating PVs, terminating transcription thus explaining a specific cancer risk. The penetrance of RTPS1 early in life is high and associated with a poor survival. However, few unaffected carriers may be encountered. Beyond RT, the tumor spectrum may be larger than initially suspected, and cancer surveillance offered to unaffected carriers (siblings or parents) and long-term survivors of RT is still a matter of discussion. RTPS2 exposes female carriers to an ill-defined risk of small cell carcinoma of the ovaries, hypercalcemic type (SCCOHT), which may appear in prepubertal females. RT surveillance protocols for these rare families have not been established. To address unresolved issues in the care of individuals with RTPS and to propose appropriate surveillance guidelines in childhood, the SIOPe Host Genome working group invited pediatric oncologists and geneticists to contribute to an expert meeting. The current manuscript summarizes conclusions of the panel discussion, including consented statements as well as non-evidence-based proposals for validation in the future.

[Update on Li-Fraumeni syndrome]. / Ein Update zum Li-Fraumeni-Syndrom.

The Li-Fraumeni syndrome (LFS, online Mendelian inheritance in man, OMIM #151623) is considered to be one of the currently known most aggressive cancer predisposition syndromes. The heterogeneous spectrum of tumors is dominated by bone and soft tissue sarcomas, various brain tumors, premenopausal breast cancer and adrenocortical carcinoma (ACC). Even in childhood the cancer risk is very strongly increased and it is not uncommon for people with LFS to develop synchronous and metachronous tumors. Typical histopathological findings and molecular genetic signatures can help towards the diagnosis. Inheritance is autosomal dominant and the penetrance appears to be more variable than previously thought. The prevalence of LFS is approximately 1:5000 with a high interregional variance. The LFS is caused by germline mutations in the TP53 gene coding for the protein p53, an essential cellular transcription factor that initiates antitumor responses to cellular stress, such as DNA damage. In people with LFS, due to the loss of functional p53, the protective mechanism of the cells is weakened resulting in a significantly increased cancer risk. In order to improve the survival of people with LFS, structured tumor early recognition and surveillance strategies are recommended; however, national and international longitudinal observational studies are needed to evaluate the cost-effort-benefit balance. For this reason, the authors have established the LFS cancer predisposition registry in which all patients with LFS and other syndromes predisposing to cancer can be registered. Detailed information can be found at www.cancer-predisposition.org .

Lysine-specific demethylase 1 restricts hematopoietic progenitor proliferation and is essential for terminal differentiation.

Lysine (K)-specific demethylase 1A (LSD1/KDM1A) has been identified as a potential therapeutic target in solid cancers and more recently in acute myeloid leukemia. However, the potential side effects of a LSD1-inhibitory therapy remain elusive. Here, we show, with a newly established conditional in vivo knockdown model, that LSD1 represents a central regulator of hematopoietic stem and progenitor cells. LSD1 knockdown (LSD1-kd) expanded progenitor numbers by enhancing their proliferative behavior. LSD1-kd led to an extensive expansion of granulomonocytic, erythroid and megakaryocytic progenitors. In contrast, terminal granulopoiesis, erythropoiesis and platelet production were severely inhibited. The only exception was monopoiesis, which was promoted by LSD1 deficiency. Importantly, we showed that peripheral blood granulocytopenia, monocytosis, anemia and thrombocytopenia were reversible after LSD1-kd termination. Extramedullary splenic hematopoiesis contributed to the phenotypic reversion, and progenitor populations remained expanded. LSD1-kd was associated with the upregulation of key hematopoietic genes, including Gfi1b, Hoxa9 and Meis1, which are known regulators of the HSC/progenitor compartment. We also demonstrated that LSD1-kd abrogated Gfi1b-negative autoregulation by crossing LSD1-kd with Gfi1b:GFP mice. Taken together, our findings distinguish LSD1 as a critical regulator of hematopoiesis and point to severe, but reversible, side effects of a LSD1-targeted therapy.