Ovarian carcinoma is an extremely rare malignancy in children, often developing on the underlying inherited background. Female carriers of pathogenic germline mutations of SMARCA4 are at risk of an aggressive type of undifferentiated ovarian cancer called small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). Regardless of age of the patient, stage of the disease, and oncological treatment, the prognosis for SCCOHT is poor. Therefore, early intervention with risk-reducing surgeries is recommended for these patients. In this study, we report genetic testing of a family with two children carrying pathogenic germline mutations of SMARCA4 and summarize the course of SCCOHT in all pediatric patients reported in the literature with constitutional defects identified within the SMARCA4 locus.

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B-cell acute lymphoblastic leukemia (B-ALL) is a malignancy caused by accumulation of immature B cells. Advances in the field, especially in genomic studies and new treatment development, significantly improved the prognosis of B-ALL over the last decades. However, the B-ALL subtype harboring Philadelphia chromosome t(9;22)(q34;q11) (Ph+ B-ALL) still remains a therapeutic challenge despite available targeted treatment with tyrosine kinase inhibitors (TKIs). The novel therapeutic regimens for adult B-ALL often include rituximab (RTX) - a monoclonal anti-CD20 antibody - for patients with >20% CD20+ blasts. Moreover, drug combinations including approved TKIs and antibodies are being tested in clinical trials. Since some TKIs display immune effector cell inhibition, investigating their immunomodulatory effects in the context of combined chemo-immunotherapies is clinically relevant for the rational combination design. We found that blasts isolated from Ph+ B-ALL patients showed the highest CD20 expression on mRNA level among defined B-ALL genetic subtypes. As Ph+ CD20+ patients may be qualified for treatment with TKIs along with RTX, this result prompted the need of investigating the effects of TKIs on immune effectors. We therefore compared how first-, second- and third-generation TKIs (imatinib, dasatinib, nilotinib, bosutinib, ponatinib) and allosteric inhibitor asciminib recently approved for the treatment of chronic myeloid leukemia (CML) affect innate and antibody-mediated cytotoxicity. B-ALL cell lines, patient-derived lymphoblasts propagated in NSG mice (primografts) and ex vivo whole blood assays were used for testing the efficacy of effector cell-mediated mechanisms in the presence of TKIs. The TKIs were compared in NK-cell based natural cytotoxicity tests, antibody-dependent cytotoxicity (ADCC) tests and phagocytosis assays with monocyte-derived macrophages. Dasatinib was also tested using whole blood ex vivo ADCC assays before and after administration of the TKI. Out of six tested TKIs, asciminib presented the most favorable profile, causing slight or no effector cell inhibition in both innate and antibody-mediated responses. In contrast, dasatinib significantly decreased the immune cells activity in all tests, reducing natural and RTX-mediated cytotoxicity of NK cells against B-ALL blasts. Dasatinib and ponatinib significantly inhibited in vitro phagocytosis of primograft B-ALL cells. To a lesser extent, cytotoxicity and phagocytosis were suppressed by imatinib, bosutinib and nilotinib. Importantly, we confirmed that the orally administered dasatinib impairs the NK cell activity in patients’ blood. Our findings indicate that the TKIs differentially impact RTX-mediated effector mechanisms. The novel, allosteric TKI asciminib could be preferentially used in combination with RTX-based immunotherapy. This work was supported by the Polish National Science Centre grant 2019/35/B/NZ5/01428 and by the Ministry of Education and Science within “Regional Initiative of Excellence” program 013/RID/2018/19." Citation Format: Krzysztof Domka, Martyna Poprzeczko, Zuzanna Urbanska, Lukasz Komorowski, Agata Pastorczak, Klaudyna Fidyt, Agnieszka Dabkowska, Mieszko Lachota, Magdalena Winiarska, Karolina Siudakowska, Elzbieta Patkowska, Łukasz Sędek, Bartosz Perkowski, Beata Krzymieniewska, Malgorzata Firczuk. Optimizing the therapeutic potential of tyrosine kinase inhibitors in chemo-immunotherapy of B-cell acute lymphoblastic leukemia involving rituximab [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3324.

Venetoclax, the best established BH3 mimetic, is a practice-changing proapoptotic drug to treat blood cancers in adults. In paediatrics, the data are less but exciting results were recently presented in relapsed or refractory leukaemias demonstrating significant clinical activity. Importantly, the interventions could be potentially molecularly guided as vulnerabilities to BH3 mimetics were reported. Currently, venetoclax is not incorporated into paediatric treatment schedules in Poland but it has been already used in patients that failed conventional therapy in Polish paediatric haemato-oncology departments. The aim of the study was to gather clinical data and correlates of all paediatric patients treated thus far with venetoclax in Poland. We set out to gather this data to help choose the right clinical context for the drug and stimulate further research. The questionnaire regarding the use of venetoclax was sent to all 18 Polish paediatric haemato-oncology centres. The data of November 2022 were gathered and analysed for the diagnoses, triggers for the intervention, treatment schedules, outcomes and molecular associations. We received response from 11 centres, 5 of which administered venetoclax to their patients. Clinical benefit, in most cases consistent with haematologic complete remission (CR), was reported in five patients out of ten, whereas five patients did not show clinical benefit from the intervention. Importantly, patients with CR included subtypes expected to show venetoclax vulnerability, such as poor-prognosis ALL with TCF::HLF fusion. We believe that BH3 mimetics have clinical activity in children and should be available to paediatric haemato-oncology practitioners in well-selected applications.

Genetic abnormalities detected in the leukemic genome became essential prognostic factors stratifying the intensity of treatment in children with acute lymphoblastic leukemia (ALL). However, only selected copy number alterations are independently associated with the clinical course of disease. Deletions within the <i>IKZF1</i> gene significantly confer to poor dzieprognosis of ALL, particularly when cooccurred with deletions of <i>CDKN2A/ B</i>, <i>PAX5</i>, and genes from PAR1 region and the concomitant lack of ERG gene deletion is present. In the project, high-density SNP array were tested on 195 childhood BCP-ALL samples to optimize the detection of copy number alterations within selected gene loci. Developed experimental protocol and data analysis enabled identification of clonal and mosaic forms of <i>IKZF1</i> deletions.