Luciana Rodrigues Carvalho Barros’s research while affiliated with Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo and other places

Chimeric antigen receptor (CAR)-T cell immunotherapy has achieved significant success against various haematological cancers, including B-cell malignancies. Its efficacy against B-cell cancers is influenced by the presence of healthy B-cells expressing the target antigen, and B-cell aplasia (BCA) serves as an indicator of successful therapy outcome. However, the precise influence of healthy B-cells on the in vivo dynamics of CAR-T cells and their ultimate impact on therapy outcomes remain unclear. Here, we propose a mathematical model to describe CAR-T cell immunotherapy in B-cell cancer patients. Our model successfully captured the interactions between different CAR-T cell phenotypes, tumour cells, and healthy B cells in patients who achieved a complete response. Using these cases, we constructed virtual scenarios to investigate how variations in baseline tumour and healthy B-cell populations, along with patient-specific factors related to CAR-T cell expansion and B-cell influx from the bone marrow, affect treatment outcomes. Our results suggest that the onset and duration of BCA is a patient-specific feature that depends primarily on the continuous influx of newly generated B cells, their proliferative capacity, and the expansion and cytotoxicity of CAR-T cells. Statement of significance This study presents a significant advancement in understanding the dynamics of CAR-T cell immunotherapy in B-cell malignancies by introducing a mathematical model that captures the complex interactions between CAR-T cells, tumour cells, and healthy B cells. The model provides crucial insights into how patient-specific factors, such as baseline tumour burden, B-cell populations, and CAR-T cell expansion, influence treatment outcomes, including the onset and duration of B-cell aplasia (BCA), a key marker of therapeutic success. Healthy B cells can act as allies, adversaries, or have a neutral effect on the therapy, depending on the tumour burden. These findings highlight the importance of personalised approaches in CAR-T cell immunotherapy, offering potential pathways to optimise treatment strategies for improved efficacy and patient outcomes.

Disclosure: F.Q. Aratani: None. D.P. Di Matteo: None. I.P. de Magalhães: None. P. Frudit: None. L.S. Motomia: None. S.K. Beeby: None. L.R. Barros: None. D.D. Bissegatto: None. L.R. Carvalho: None. Background: Deficiency of one or more pituitary hormones is defined as hypopituitarism. In the literature, molecular diagnosis (MD) is defined in 12% by the Sanger sequencing and large scale sequencing increased this number to 15%. Aim: To perform whole exome sequencing (WES) in a cohort of patients with congenital hypopituitarism (CH) naïve to MD approach. Patients: Nine patients with CH followed in a single Brazilian tertiary center were included. Methods: Libraries were prepared with kits from Agilent and sequenced on Hi-Seq (Illumina). The variants were called following GATK best practices, using the Haplotypecaller and genome version hg38. They were classified in the Franklin by genoox (https://franklin.genoox.com/clinical-db/home). WES that did not pass the platform's initial quality control and variants that did not reach an adequate confidence level (low/medium confidence: VAF < 50%) were excluded. The remaining variants were classified according to ACMG criteria. Results: Three among 9 patients presented allelic variants and aredescribed here. Case 1: A 22-year-old female presented height of 143 cm (-3,13 SDS) at the first visit without signs of puberty, had delayed bone age (DBA), hypoplastic adenohypophysis, interrupted pituitary stalk (IPS) and ectopic neurohypophysis (ENH) at the magnetic resonance imaging (MRI). Hormonal profile showed low E2, GH, FSH and LH. Twoheterozygous missense variants in the ALMS1 gene (c.5450G>A : p.Arg1817GIn; and ALMS1:c.4225G>C: p.Ala1409Pro) were seen in the exome; both classified as VUS according to ACMG criteria. This allelic variant is related to Alstrom Syndrome. Case 2: A 7-year-old female presented with short stature and was diagnosed with GH followed by LH/FSH, TSH and ACTH deficiencies. At MRI presented IPS and ENH. A heterozygous variant in the PROK2 gene c.364C>T p.R122 with a premature stop codon and truncated protein was present and classified as probably pathogenic according to ACMG criteria. This variant was already described with hypogonadotropic hypogonadism (HH) with or without anosmia. Case3: A 15-year-old male was referred with growth hormone deficiency (GHD), DBA, and HH. Growth hormone replacement was started followed by testosterone. Despite delayed puberty, the testes were normal in size. WES showed a variant c.629G>A:p.Trp210*, in hemizygosity in IGSF1 gene and was classified as probably pathogenic according to ACMG criteria. Loss-of-function mutations in IGSF1 may cause an X-linked syndrome of central hypothyroidism, macroorchidism and delayed puberty (delayed rise of testosterone, but normal timing of testicular growth). Conclusion: WES in a cohort of patients with congenital hypopituitarism naïve to molecular diagnosis revealed 33% (3/9) with positive genetic findings, two of them with clinical significance and family segregation according to the genetic inheritance. Presentation: 6/3/2024

We evaluated the prevalence of pathogenic/likely pathogenic germline variants (PGV) in Brazilian pancreatic adenocarcinoma (PC) patients, that represent a multiethnic population, in a cross-sectional study. We included 192 PC patients unselected for family history of cancer. We evaluated a panel of 113 cancer genes, through genomic DNA sequencing and 46 ancestry-informative markers, through multiplex PCR. The median age was 61 years; 63.5% of the patients presented disease clinical stages III or IV; 8.3% reported personal history of cancer; 4.7% and 16.1% reported first-degree relatives with PC or breast and/or prostate cancer, respectively. Although the main ancestry was European, there was considerable genetic composition admixture. Twelve patients (6.25%) were PGV carriers in PC predisposition genes (ATM, BRCA1, BRCA2, CDKN2A, MSH2, PALB2) and another 25 (13.0%) were PGV carriers in genes with a limited association or not previously associated with PC (ACD, BLM, BRIP1, CHEK2, ERCC4, FANCA, FANCE, FANCM, GALNT12, MITF, MRE11, MUTYH, POLE, RAD51B, RAD51C, RECQL4, SDHA, TERF2IP). The most frequently affected genes were CHEK2, ATM and FANC. In tumor samples from PGV carriers in ACD, BRIP1, MRE11, POLE, SDHA, TERF2IP, which were examined through exome sequencing, the main single base substitutions (SBS) mutational signature was SBS1+5+18, probably associated with age, tobacco smoking and reactive oxygen species. SBS3 associated with homologous repair deficiency was also represented, but on a lower scale. There was no difference in the frequency of PGV carriers between: (a) patients with or without first-degree relatives with cancer; and (b) patients with admixed ancestry versus those with predominantly European ancestry. Furthermore, there was no difference in overall survival between PGV carriers and non-carriers. Therefore, genetic testing should be offered to all Brazilian pancreatic cancer patients, regardless of their ancestry. Genes with limited or previously unrecognized associations with pancreatic cancer should be further investigated to clarify their role in cancer risk.

Serine integrases (Ints) are a family of site-specific recombinases (SSRs) encoded by some bacteriophages to integrate their genetic material into the genome of a host. Their ability to rearrange DNA sequences in different ways including inversion, excision, or insertion with no help from endogenous molecular machinery, confers important biotechnological value as genetic editing tools with high host plasticity. Despite advances in their use in prokaryotic cells, only a few Ints are currently used as gene editors in eukaryotes, partly due to the functional loss and cytotoxicity presented by some candidates in more complex organisms. To help expand the number of Ints available for the assembly of more complex multifunctional circuits in eukaryotic cells, this protocol describes a platform for the assembly and functional screening of serine-integrase-based genetic switches designed to control gene expression by directional inversions of DNA sequence orientation. The system consists of two sets of plasmids, an effector module and a reporter module, both sets assembled with regulatory components (as promoter and terminator regions) appropriate for expression in mammals, including humans, and plants. The complete method involves plasmid design, DNA delivery, testing and both molecular and phenotypical assessment of results. This platform presents a suitable workflow for the identification and functional validation of new tools for the genetic regulation and reprogramming of organisms with importance in different fields, from medical applications to crop enhancement, as shown by the initial results obtained. This protocol can be completed in 4 weeks for mammalian cells or up to 8 weeks for plant cells, considering cell culture or plant growth time.

Genetic analysis of sporadic Medullary Thyroid Carcinoma (MTC) has revealed somatic variants in RET, RAS, and occasionally other genes. However, around 20% of sporadic MTC patients lack a known genetic driver. To uncover potential new somatic or germline drivers we analyze a distinct cohort of patients with sporadic, very early-onset and aggressive MTC. Germline and somatic DNA exome sequencing was performed in 19 patients, previously tested negative for germline RET variants. Exome sequencing of 19 germline samples confirmed the absence of RET and identified an NF1 pathogenic variant in one patient. Somatic sequencing was successful in 15 tumors revealing RET variants in 80%, predominantly p.Met918Thr which was associated with disease aggressiveness. In RET-negative tumors, pathogenic variants were found in HRAS and NF1. The NF1 germline and somatic variants were observed in a patient without a prior clinical diagnosis of Neurofibromatosis type 1, demonstrating that the loss of heterozygosity of NF1 functions as a potential MTC driver. Somatic copy number alterations analysis revealed chromosomal alterations in 53.3% of tumors, predominantly in RET-positive cases, with losses in chromosomes 9 and 22 being the most prevalent. This study reveals that within a cohort of early-onset non-hereditary MTC, RET remains the major driver gene. In RET-negative tumors, NF1 and RAS are drivers of sporadic MTC. In addition, in young patients without a RET germline mutation, a careful clinical evaluation with a consideration of germline NF1 gene analysis is ideal to exclude Neurofibromatosis type 1.

Background aims: Amidst the success of cell therapy for the treatment of onco-hematological diseases, the first recently Food and Drug Administration-approved gene therapy product for patients with transfusion-dependent β-thalassemia (TDT) indicates the feasibility of gene therapy as curative for genetic hematologic disorders. This work analyzed the current-world scenario of clinical trials involving gene therapy for β-hemoglobinopathies. Methods: Eighteen trials for patients with sickle cell disease (SCD) and 24 for patients with TDT were analyzed. Results: Most are phase 1 and 2 trials, funded by the industry and are currently recruiting volunteers. Treatment strategies for both diseases are fetal hemoglobin induction (52.4%); addition of wild-type or therapeutic β-globin gene (38.1%) and correction of mutations (9,5%). Gene editing (52.4%) and gene addition (40.5%) are the two most used techniques. The United States and France are the countries with the greatest number of clinical trials centers for SCD, with 83.1% and 4.2%, respectively. The United States (41.1%), China (26%) and Italy (6.8%) lead TDT trials centers. Conclusions: Geographic trial concentration indicates the high costs of this technology, logistical issues and social challenges that need to be overcome for gene therapy to reach low- and middle-income countries where SCD and TDT are prevalent and where they most impact the patient's health.

Chimeric Antigen Receptor (CAR)-T cell therapy long-term follow-up studies revealed non-durable remissions in a significant number of patients. Some of the mechanisms underlying these relapses include poor CAR T cell cytotoxicity or persistence, as well as antigen loss or lineage switching in tumor cells. In order to investigate how antigen-mediated resistance mechanisms affect therapy outcomes, we develop a mathematical model based on a set of integral-partial differential equations. Using a continuous variable to describe the level of antigen expression of tumor cells, we recapitulated important cellular mechanisms across patients with different therapeutic responses. Fitted with clinical data, the model successfully captured the dynamics of tumor and CAR-T cells for several hematological cancers. Furthermore, the role played by these mechanisms are explored with regard to different biological scenarios, such as pre-existing or acquired mutations, providing a deeper understanding of key factors underlying resistance to CAR-T cell immunotherapy. Statement of significance Our study introduces the first mathematical model to characterize the influence of a continuous level of antigen expression on the interplay between Chimeric Antigen Receptor (CAR)-T cells and cancer cells. We examine various cellular mechanisms across different hematologic cancers, taking into account both antigen-positive and antigen-negative relapses. Our findings shed light on the role of antigen density in CAR-T cell therapies and provide a valuable framework to investigate resistance with potential to improve patient’s outcomes.