Clinical Trial: Diagnostic Value of Bone Marrow Tryptase in Systemic Mastocytosis

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Evaluation of the Diagnostic Value of Level of Bone Marrow Tryptase in Adult Systemic Mastocytosis

Brief Summary:

The hypothesis of the study is that Bone Marrow Tryptase (MT) level is a diagnostic marker of Systemic Mastocytosis (SM). Determination of the bone marrow tryptase in Bone Marrow Aspirate (BMA) could be a new diagnostic criteria for systemic mastocytosis with sensitivity close to 100% and a low false negative rate. This new test could be useful to improve the ability to diagnose accurately systemic mastocytosis (in particular the indolent forms). Because of its limited invasiveness compared to bone marrow biopsy, it could also be considered as a test performed before bone marrow biopsy. Only patients with high bone marrow tryptase would then undergo bone marrow biopsy.

In the future and if validated by this study, bone marrow tryptase could be a useful marker of mast cell load and help to monitor the efficacy of treatment in systemic mastocytosis.


Detailed Summary:

Mastocytosis are a group of disorders characterized by clonal accumulation of mast cells in various organs. Diagnosis of mastocytosis is challenging and patients remain undiagnosed for years. Using the diagnostic criteria defined by the World Health Organization (WHO) mastocytosis can be divided between Cutaneous Mastocytosis (CM) and Systemic Mastocytosis (SM).

Study suggested that measurement of tryptase in plasma from a Bone Marrow Aspirate (from BMA) could be useful for the diagnosis of SM. Results from a preliminary study at Toulouse University Hospital suggested that a Bone Marrow Tryptase Level (MT) of 50 µg/L or more may be a more sensitive diagnostic criterion (sensitivity of 94.7%) than the histological result of BMB (the major diagnostic criterion for SM with a sensitivity of 68 to 80% in expert centers) for diagnosis of SM in patients with mastocytosis in skin.

Because this preliminary study was done on a limited number of patients and in a single center, the diagnostic value of MT for the diagnosis of SM, has to be confirmed on a larger and more representative population.

In addition, the investigators propose to evaluate:

  • The diagnostic accuracy of MT for diagnosis of SM in patients without mastocytosis in skin;
  • The diagnostic accuracy of absolute and corrected MT for diagnosis of SM with and without mastocytosis in skin;
  • The diagnostic accuracy of MT/ST ratio for diagnosis of SM with and without mastocytosis in skin;
  • The diagnostic accuracy of flow cytometry performed on cells collected by BMA and maintained in a preservative solution for diagnosis of SM with and without
    Sponsor: University Hospital, Toulouse

    Current Primary Outcome: Bone marrow tryptase level [ Time Frame: Day 4 after bone marrow aspiration ]

    Aliquot of the bone marrow aspirate sample will be used after centrifugation for measurements of bone marrow tryptase level.


    Original Primary Outcome: Same as current

    Current Secondary Outcome:

    • The bone marrow tryptase level for differential diagnosis between systemic mastocytosis and cell mast activation syndrome [ Time Frame: Day 4 after bone marrow aspiration ]
      Aliquot of the bone marrow aspirate sample will be used after centrifugation for measurements of bone marrow tryptase level.
    • The bone marrow tryptase/serum tryptase ratio for diagnosis of systemic mastocytosis with and without mastocytosis in skin [ Time Frame: Day 4 after bone marrow aspiration ]
    • The absolute and corrected bone marrow tryptase level for diagnosis of systemic mastocytosis with and without mastocytosis in skin [ Time Frame: Day 4 after bone marrow aspiration ]
      The degree of dilution of the bonne marrow aspirate by peripheral blood will be estimated by comparing the percentage of CD16bright vs CD16low granulocytes in bone marrow samples and used to adjust the bone marrow tryptase.
    • Flow cytometry performed on cells collected by bone marrow aspirate and maintained in a preservative solution (TransFix®) to detect mast cells expressing CD25 and/or CD2 for diagnosis of systemic mastocytosis with and without mastocytosis in skin [ Time Frame: Day 4 after bone marrow aspiration ]
      Immunophenotyping of bone marrow mastocytes will be performed on bone marrow aspiration stabilized by Transfix using a pre-defined mixture of anti-CD45/CD117/CD34/CD2/CD25/CD16 antibodies.
    • Quantification of KIT mutations-positive cells fraction in peripheral blood for systemic mastocytosis diagnosis,correlation with results of medullar tryptase level, medullar/systemic tryptase ratio and absolute and corrected medullar tryptase level [ Time Frame: Day 4 after bone marrow aspiration ]
      Genomic DNA from total leucocytes will be purified from the peripheral blood samples and used for the quantification of the kit mutation by qPCR


    Original Secondary Outcome: Same as current

    Information By: University Hospital, Toulouse

    Dates:
    Date Received: May 5, 2015
    Date Started: October 2015
    Date Completion: July 2019
    Last Updated: April 24, 2017
    Last Verified: April 2017