p53 protein expression independently predicts outcome in patients with lower-risk myelodysplastic syndromes with del(5q)

Abstract

Del(5q) myelodysplastic syndromes defined by the International Prognostic Scoring System as low- or intermediate-1-risk (lower-risk) are considered to have an indolent course; however, recent data have identified a subgroup of these patients with more aggressive disease and poorer outcomes. Using deep sequencing technology, we previously demonstrated that 18% of patients with lower-risk del(5q) myelodysplastic syndromes carry TP53 mutated subclones rendering them at higher risk of progression. In this study, bone marrow biopsies from 85 patients treated with lenalidomide in the MDS-004 clinical trial were retrospectively assessed for p53 expression by immunohistochemistry in association with outcome. Strong p53 expression in ≥ 1% of bone marrow progenitor cells, observed in 35% (30 of 85) of patients, was significantly associated with higher acute myeloid leukemia risk (P=0.0006), shorter overall survival (P=0.0175), and a lower cytogenetic response rate (P=0.009), but not with achievement or duration of 26-week transfusion independence response. In a multivariate analysis, p53-positive immunohistochemistry was the strongest independent predictor of transformation to acute myeloid leukemia (P=0.0035). Pyrosequencing analysis of laser-microdissected cells with strong p53 expression confirmed the TP53 mutation, whereas cells with moderate expression predominantly had wild-type p53. This study validates p53 immunohistochemistry as a strong and clinically useful predictive tool in patients with lower-risk del(5q) myelodysplastic syndromes. This study was based on data from the MDS 004 trial (clinicaltrials.gov identifier: NCT00179621).

Copyright© Ferrata Storti Foundation.

Figures

Figure 1.

The p53-DO1 stain shows cells with moderate (2+) and strong (3+) nuclear staining (top). The lower left panel shows a BM sample with only scattered strong p53-positive staining (red circle) around the 1% level by both manual and automated image assessment. The lower right panel shows a BM sample with the presence of scattered weak (1+; yellow circle) and moderate (2+; orange circle) p53-positive staining cells, but no cells with strong (3+) nuclear staining.

Figure 2.

Laser-microdissection of BM cells with strong (3+; red circle), moderate (2+; orange circle), and negative p53-staining collected in three separate tubes from the same formalin fixed, paraffin-embedded BM sample (patient 34, BM sample at 105 months from initial diagnosis). TP53 mutation analysis by pyrosequencing using DNA from microdissected cells. The images were taken with a Leica Laser Microscope at 60× magnification before (left) and after (right) laser-microdissection; p53-negative microdissected cells are not shown in the upper images. Patient 34 had classical 5q- syndrome [46, XX, del(5q)] with a previously known C275F (G>T) TP53 mutation.

Figure 3.

Overall survival by the presence of

Figure 4.

Probability of AML progression by the presence of

Figure 5.

Increase of p53 in eight of 21 patients after 3 months, and in one patient (patient 5) after 12 months. Patients 5, 6, 9, and 17 had cytogenetic evolution with complex karyotypes at 12, 22, 6, and 3 months, respectively. The decrease in p53 in the last sample in patient 8 may reflect very low BM cellularity (10%). The histology panels show p53-DO1 staining in BM samples from Patient 5 at screening (upper right) and after 12 months (lower left) at 20×/40× magnification. Cells with strong (3+) p53 expression were negative for CD34 (lower middle) and positive for hemoglobin (lower right). No increase in CD34+ cells was seen, but aberrant expression of CD34 in megakaryocytes was noted.