Avaliação por imagem de medidas esplênicas e tímicas como biomarcadores de resposta em pacientes com câncer tratados com imunoterapia / Imaging evaluation of thymic and splenic measurements as response biomarkers in cancer patients treated with immunotherapy

INTRODUÇÃO: Em menos de duas décadas, a imunoterapia consolidou-se como um dos pilares do tratamento do câncer. Apesar da sua potencial elevada eficácia e resposta duradoura, a proporção de pacientes que apresentam resposta objetiva é relativamente baixa e existem poucos biomarcadores para selecionar os pacientes com maior potencial de resposta. OBJETIVO: Nossa hipótese era de que era possível avaliar globalmente o sistema imune do paciente através da mensuração por imagem do timo e do baço e usar essas métricas como fator prognóstico e preditivo de resposta a bloqueadores de checkpoint. RESULTADOS: Os principais resultados foram: 1) As medidas tímicas não se correlacionam com a sobrevida em pacientes tratados com imunoterapia; 2) Há aumento do volume esplênico após o uso de imunoterapia na maior parte dos pacientes, mas o grau de aumento não se correlaciona com resposta à terapia; 3) Maior volume esplênico está associado a pior sobrevida livre de progressão em pacientes com melanoma tratados com imunoterapia, mas essa correlação não pôde ser replicada em outros tipos tumorais. CONCLUSÃO: a espessura tímica não se correlaciona com desfechos clínicos em pacientes oncológicos tratados com imunoterapia. Menor volume esplênico antes de iniciar imunoterapia está relacionada a melhor prognóstico em pacientes com melanoma, mas não em outros tipos tumorais.

INTRODUCTION: In less than two decades, immunotherapy has established itself as one of the pillars of cancer treatment. Despite its potentially high efficacy and long-lasting response, the proportion of patients who have an objective response is relatively low and there are few biomarkers to select patients with the greatest response potential. OBJECTIVE: Our hypothesis was that it was possible to assess the patient's immune system globally by measuring the thymus and spleen by imaging and using these metrics as a prognostic and predictive factor of response to immune checkpoint inhibitors. RESULTS: The main results were: 1) Thymic measurements do not correlate with survival in patients treated with immunotherapy; 2) There is an increase in splenic volume after the use of immunotherapy in most patients, but the degree of increase does not correlate with response to therapy; 3) Greater splenic volume is associated with worse progression free survival in patients with melanoma treated with immunotherapy, but this correlation could not be replicated in other tumor types. CONCLUSION: thymic thickness does not correlate with clinical outcomes in cancer patients treated with immunotherapy. Smaller splenic volume before starting immunotherapy is associated with better prognosis in patients with melanoma, but not other tumor types

Inactivation of the Prolyl Isomerase Pin1 Sensitizes BRCA1-Proficient Breast Cancer to PARP Inhibition.

PARP inhibitor monotherapies are effective to treat patients with breast, ovary, prostate, and pancreatic cancer with BRCA1 mutations, but not to the much more frequent BRCA wild-type cancers. Searching for strategies that would extend the use of PARP inhibitors to BRCA1-proficient tumors, we found that the stability of BRCA1 protein following ionizing radiation (IR) is maintained by postphosphorylational prolyl-isomerization adjacent to Ser1191 of BRCA1, catalyzed by prolyl-isomerase Pin1. Extinction of Pin1 decreased homologous recombination (HR) to the level of BRCA1-deficient cells. Pin1 stabilizes BRCA1 by preventing ubiquitination of Lys1037 of BRCA1. Loss of Pin1, or introduction of a BRCA1-mutant refractory to Pin1 binding, decreased the ability of BRCA1 to localize to repair foci and augmented IR-induced DNA damage. In vitro growth of HR-proficient breast, prostate, and pancreatic cancer cells were modestly repressed by olaparib or Pin1 inhibition using all-trans retinoic acid (ATRA), while combination treatment resulted in near-complete block of cell proliferation. In MDA-MB-231 xenografts and triple-negative breast cancer patient-derived xenografts, either loss of Pin1 or ATRA treatment reduced BRCA1 expression and sensitized breast tumors to olaparib. Together, our study reveals that Pin1 inhibition, with clinical widely used ATRA, acts as an effective HR disrupter that sensitizes BRCA1-proficient tumors to PARP inhibition. SIGNIFICANCE: PARP inhibitors have been limited to treat homologous recombination-deficient tumors. All-trans retinoic acid, by inhibiting Pin1 and destabilizing BRCA1, extends benefit of PARP inhibitors to patients with homologous recombination-proficient tumors.See related commentary by Cai, p. 2977.

Destruction of a Microtubule-Bound MYC Reservoir during Mitosis Contributes to Vincristine's Anticancer Activity.

Tightly regulated activity of the transcription factor MYC is essential for orderly cell proliferation. Upon deregulation, MYC elicits and promotes cancer progression. Proteasomal degradation is an essential element of MYC regulation, initiated by phosphorylation at Serine62 (Ser62) of the MB1 region. Here, we found that Ser62 phosphorylation peaks in mitosis, but that a fraction of nonphosphorylated MYC binds to the microtubules of the mitotic spindle. Consequently, the microtubule-destabilizing drug vincristine decreases wild-type MYC stability, whereas phosphorylation-deficient MYC is more stable, contributing to vincristine resistance and induction of polyploidy. PI3K inhibition attenuates postmitotic MYC formation and augments the cytotoxic effect of vincristine. IMPLICATIONS: The spindle's function as a docking site for MYC during mitosis may constitute a window of specific vulnerability to be exploited for cancer treatment.

Serial-omics of P53-/-, Brca1-/- Mouse Breast Tumor and Normal Mammary Gland.

This study demonstrates a liquid-liquid extraction for the sequential tandem mass spectrometry (LC-MS/MS) analysis of non-polar lipids, polar metabolites, proteins and phosphorylation sites from a single piece of tissue. Extraction of 10 mg BRCA-/-, p53-/- breast tumor tissue or normal mammary gland tissue with methyl-tert-butyl ether (MTBE) results in three phases: an upper non-polar phase containing 1,382 lipids, a lower polar phase with 805 metabolites and a precipitated protein pellet with 4,792 proteins with 1,072 phosphorylation sites. Comparative analysis revealed an activated AKT-mTOR pathway in tumors. Tumors also showed a reduction of phosphorylation sites involved in transcription and RNA splicing and decreased abundance of enzymes in lipid synthesis. Analysis of polar metabolites revealed a reduction in glycolysis, pentose phosphate pathway, polyamines and nucleotides, but an increase in TCA and urea cycle intermediates. Analysis of lipids revealed a shift from high triglycerides in mammary gland to high phospholipid levels in tumors. The data were integrated into a model showing breast tumors exhibit features on the proteomic, lipidomic and metabolomic level that are distinct from normal breast tissue. Our integrative technique lends itself to samples such as tumor biopsies, dried blood spots and fluids including urine and CSF to develop biomarkers of disease.