P53 and CD34 Immunohistochemical Expression on Bone Marrow Biopsy As Predictive Marker of Response to Erythropoietin in Low Risk Myelodysplastic Syndrome

Introduction: Erythropoietin stimulating agents (ESAs) are first-line therapy for International Prognostic Scoring System (IPSS)-low risk myelodysplastic syndrome (MDS) when symptomatic anaemia (Hb <10 g/dl) is associated with serum erythropoietin (EPO) <500 mU/mL. Treatment response rate, according to international working group (IWG) response criteria (1- 5), ranges from 40 to 60%.

Attempts have been made to build prognostic scores (integrating transfusion need, erythropoietin level, R-IPSS and ferritin) able to predict response to ESAs (6-7). No data concerning the predictive value of morphological and immunohistochemical analysis on bone marrow biopsy in low risk MDS patients are emerged till now.

Methods: We retrospectively examined 96 IPSS low/int-1 MDS patients treated with ESAs in order to evaluate the morphological and immunohistochemical features of the bone marrow biopsies performed at baseline.

All the patients had hemoglobin (Hb) ≤10 g/dL and serum EPO <500 mU/mL and received EPO alfa or β 40 000-80 000 IU/week for at least 12 weeks. Response to ESAs treatment was evaluated according to IWG 2006 criteria.

A detailed analysis of the morphological features (including quantitative and qualitative changes in the erythroid, myeloid and megakariopoyetic lineages) was performed, together with an immunohistochemical evaluation of p53 expression and CD34-positive blasts percentage.

Results: Sixty-eight percent of the patients were classified as responder while 32% as non-responder. The morphologic profiles of the responder and non-responder did not differ significantly.

A significant correlation was found between the response to the therapy and a percentage of CD34-positive blasts > 3% (univariate analysis: p= .0211).

Moreover p53 expression in less than 1% of the nucleated cells correlated with the treatment response (univariate analysis: p = .0086). These results were also confirmed on multivariate analysis (p= .002).

Fifty-eight percent of patients maintained response to ESAs for the entire duration of the follow up while 42% lost the response (median follow up: 35 months). More than 3% CD34-positive blasts was associated with a higher probability to lose the response to ESAs (p = .00003).

Kaplan-Meier method was than applied to estimate the response duration. Patients with more than 3% CD34-positive blasts showed earlier loss of response in comparison with those with a lower percentage of blasts (p value= .0003; HR=3.9, IC 95% 1.8154-8.6238).

Finally, the expression of p53 in more than ≥ 1% of the nucleated cells correlated with the loss of response before 24 mounts (p value= 0.029).

Conclusions: Our study identifies 2 well-known parameters that could be useful to better predict outcome of ESAs therapy in low risk MDS patients. Therefore role of bone marrow biopsy together with its diagnostic contribution in the clinical evaluation of MDS patients (cellularity, morphologic dysplasia, percentage of CD34-positive blasts, grading of bone marrow fibrosis) could be helpful as a predictive tool in ESAs candidate patients. Further studies based on larger series of patients are needed to confirm these preliminary results.