Prognostic Impact of Immunohistochemical p53 Expression in Bone Marrow Biopsy in Higher Risk MDS: a Pilot Study

Exploring p53 protein expression and its link to TP53 mutation in myelodysplasia-related malignancies-Interpretive challenges and potential field of applications

AIMS

TP53 alterations have a significant prognostic effect in myeloid neoplasms. Our objective was to investigate the TP53 gene mutation status, p53 protein expression and their relationship in dysplasia-related myeloid neoplasms with varying levels of myeloblast counts.

METHODS AND RESULTS

A total of 76 bone marrow biopsy samples with different blast counts were analysed. Total and strong (3+) p53 expression was determined. Dual immunohistochemical staining was performed to determine the cell population associated with p53 expression. NGS analysis was performed using the Accel-Amplicon Comprehensive TP53 panel. Both p53 expression and TP53 VAF showed a significant correlation with the myeloblast ratio (P < 0.0001); however, p53 expression was also present in other cell lineages. The VAF value exhibited a significant correlation with p53 expression. A high specificity (0.9800) was observed for TP53 mutation using the ≥ 10% strong (3+) p53 cut-off value, although the sensitivity (0.4231) was low.

CONCLUSIONS

Strong (3+) p53 expression using a ≥ 10% cut-off value accurately predicts TP53 mutation but does not reveal the allelic state. The p53 expression is significantly influenced by myeloblast count, and histological interpretation should consider the presence of intermixed non-neoplastic marrow cells with varying physiological p53 expression.

Accuracy of bone marrow histochemical TP53 expression compared to the detection of TP53 somatic mutations in patients with myelodysplastic syndromes harbouring a del5q cytogenetic abnormality

TP53 gene mutations are common in Myelodysplastic Syndromes (MDS) with del5q and have a clinical and prognostic significance. Next Generation Sequencing (NGS) is an accurate, but expensive, technique, and not commonly available. Immunohistochemistry (IHC) for TP53 expression has been recently used as a surrogate to assess TP53 mutations. To compare the concordance between TP53 expression in IHC and TP53 mutations by NGS, 30 cases with MDS harbouring a del5q abnormality were evaluated. Overall, 10/30 patients (33.3%) had TP53 mutations by NGS, while 16/29 (55.1%) had TP53 overexpression in IHC. TP53 expression by IHC had a 70% sensitivity to identify patients with TP53 mutation by NGS, but its specificity was low (52.6%, kappa = 0.198; P = 0.24). In addition, ROC curve analyses showed that the overall diagnostic value (accuracy) of TP53 expression in IHC to identify patients with TP53 mutation by NGS was 68% in the whole study sample and 67% in patients with isolated del5q-. In both cases, the areas under the curves did not attain the statistical significance (P = 0.11 and P = 0.29, respectively). Based on the ROC curve, the cut-off of 2.3% TP53 expression in IHC was shown to be the best cut-off to identify TP53 mutations: using this cut-off, the agreement between TP53 expression and TP53 mutation by NGS reached statistical significance (kappa = 0.42; P = 0.023). In conclusion, the agreement between TP53 expression in IHC and TP53 mutation analysis by NGS is rather unsatisfactory in MDS patients with del5q at the standard cut-off. Thus, the IHC technique cannot be considered a valid alternative to NGS evaluation of TP53 mutational status in these patients.

CD34-Positive Blast Count and p53 Expression in Bone Marrow Biopsies of Patients with Low-Risk Myelodysplastic Syndromes: Potential Predictive Tools of Response to Erythropoietin Stimulating Agents

INTRODUCTION

The first-line therapy for patients with low-risk myelodysplastic syndromes (MDSs) commonly consists of erythropoietin stimulating agents (ESAs), with a response rate ranging from 34 to 62%. For nonresponder patients, outside clinical trials, blood transfusions are the most frequent therapeutic option, with detrimental effect on the quality of life and with risks of iron-overload. Since no studies have been yet conducted on this topic, we investigated the potential predictive role of bone marrow (BM) histological evaluation in patients treated with ESAs.

MATERIALS AND METHODS

We performed a morphological and immunohistochemical retrospective analysis of BM biopsies of 96 patients with low-risk MDSs subsequently treated with ESAs.

RESULTS

In our series, substantial morphological overlap was found between responder and nonresponder patients. On the contrary, patients with a percentage of CD34-positive blasts >3% or with p53 protein expression <1% responded with a significantly higher frequency to ESAs.

CONCLUSIONS

Our study reinforces the role of BM biopsy as diagnostic tool in MDSs, being also able to supply information related to response to ESAs and to its loss over time.

High-level MYC expression associates with poor survival in patients with acute myeloid leukemia and collaborates with overexpressed p53 in leukemic transformation in patients with myelodysplastic syndrome

INTRODUCTION

Patients with mutated and overexpressed p53 have an aggressive course in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Studies on the impact of MYC expression in AML are limited. This is the first study to evaluate MYC expression and p53 status in AML and MDS.

METHODS

We identified 214 patients, 101 AML, 79 MDS, and 34 negative control patients. We retrospectively assessed p53 and MYC expression by immunohistochemistry and correlated MYC expression with p53 expression and aberrational status of TP53.

RESULTS

The level of both p53 and MYC expression was significantly higher in AML (mean: 9.7%; 12.1%) and MDS (mean: 5.2%; 5.5%) patients compared with control cases (mean: 0.18%; 2.3%; P = .001-0.02). p53 and MYC expression levels were even more elevated in AML when compared to MDS patients (P < .001). MYC expression was significantly associated with p53 expression and TP53 aberration in AML patients but not in MDS patients (P < .001). p53 expression and >20% MYC expression showed an adverse impact on overall survival (OS) (P < .05) in AML patients while p53 but not MYC expression showed an adverse impact on OS in MDS patients. MYC and p53 dual expression, as well as combined MYC expression and TP53 aberration, showed negative impact on OS in AML patients. MDS patients with leukemic transformation revealed an interval increase in expression of both p53 and MYC.

CONCLUSION

High-level MYC expression associates with p53 abnormality and poor survival in AML. MYC may provide proliferative advantage for leukemic progression in p53 dependent and independent manner.

TP53 in Myelodysplastic Syndromes: Recent Biological and Clinical Findings

TP53 dysregulation plays a pivotal role in the molecular pathogenesis of myelodysplastic syndromes (MDS), identifying a subgroup of patients with peculiar features. In this review we report the recent biological and clinical findings of TP53-mutated MDS, focusing on the molecular pathways activation and on its impact on the cellular physiology. In MDS, TP53 mutational status is deeply associated with del(5q) syndrome and its dysregulation impacts on cell cycle, DNA repair and apoptosis inducing chromosomal instability and the clonal evolution of disease. TP53 defects influence adversely the MDS clinical outcome and the treatment response rate, thus new therapeutic approaches are being developed for these patients. TP53 allelic state characterization and the mutational burden evaluation can therefore predict prognosis and identify the subgroup of patients eligible for targeted therapy. For these reasons, in the era of precision medicine, the MDS diagnostic workup cannot do without the complete assessment of TP53 mutational profile.