Important steps towards diagnostic standardization

Authors: N. Gökbuget ¹, R. Bassan ², H. Dombret ³, R. Foà ⁴, J. Ribera ^5, R. Willemze ⁶, D. Hoelzer ^7
1 Universitätsklinikum Frankfurt, Germany; ² Azienda Ospedaliera - Ospedali Riuniti di Bergamo, Italy; ³ Assistance Publique - Hôpitaux de Paris, France; ⁴ Dipartimento di Biotecnologie Cellulari ed Ematologia, Università degli Studi di Roma "La Sapienza", Italy; ⁵ Institut Català d'Oncologia-Hospital Universitari Germans Trias i Pujol, Spain; ⁶ Leiden University Medical Center, The Netherlands; ⁷ ONCOLOGIKUM, Frankfurt am Museumsufer, GermanyInformation Letter No.5, August 2008

The European Working Group for Adult ALL was founded in 2002 as part of the European LeukemiaNet. Acute lymphoblastic leukemia (ALL ) in adults is a rare disease with a variety of subtypes showing highly significant differences in terms of clinical manifestation, disease biology and outcome. Therefore most ongoing trials for de novo ALL are subtype adjusted and risk stratified. Diagnostic standardisation is therefore an essential pre-requisite for the achievement of major aims of the EWALL which are 1. comparative analysis and 2. joint clinical trials.
As a first step, the group defined under the leadership of R. Foà standards for diagnostic confirmation of ALL with a differentiation between 1. minimal prerequisites which may also be applicable in developing countries and 2. optimal pre-requisites which should be the standard in the EWALL group. These definitions have been discussed with the workpackage on diagnostics (WP10) and are available through the ELN website.
In 2007 major decisions were made regarding the initiation of joint clinical trials. The first one was started in Juli 2007 in elderly Ph-positive ALL s with P. Rousselot as principal investigator. It is based on a chemotherapy backbone for treatment of elderly ALL which was designed by the EWALL based on French and German prospective trials for elderly ALL . Patients with Ph-positive ALL receive a low intensity induction chemotherapy with dasatinib in parallel. The initial phase is followed by sequential therapy with chemotherapy consolidation cycles and dasatinib cycles and finally a maintenance phase. The study is activated in France and upon activation in Italy, Spain and Poland.
Secondary endpoints of this trial are molecular response based on quantitative evaluation of BCR-ABL and the incidence and type of mutations which confer resistance to imatinib, dasatinib and other tyrosine kinase inhibitors. The analysis will be done in predefined central laboratories in each participating country. Clearly standards for the diagnostic procedure had to be defined, which were not available for analysis of m-BCR which is the most frequent BCRABL breakpoint in ALL . Under the leadership of H. Pfeifer the central laboratories exchanged information on applied methodologies. During a meeting at the EHA-10 in Vienna with representatives of the laboratories, the differences were discussed and the group agreed on common standards for quantiative BCR-ABL evaluation and for detection of mutations. Furthermore, there was an agreement to perform lab rounds in the EWALL laboratories in collaboration with the European Study Group on minimal residual disease detection in childhood acute lymphoblastic leukemia (ESG-MRD-ALL ).
The methodology for lab rounds was developed with support from the German CML Study Group (A. Hochhaus et al). The aim of this trial is to assess the variance of results obtained from different labs using different amplification platforms and different optimised protocols for cDNA synthesis and RT-QPCR conditions.
Two further EWALL trials in elderly ALL are planned for 2008 and 2009 in collaboration with Mundipharma. The aim is to evaluate the drug Forodesine in two different settings. Again, in this trial minimal residual disease (MRD) will be an entry criterium and also an endpoint. Two different methods are available for MRD-evaluation in ALL 1. based on PCR detection of individual rearrangements of TCR- and IgH-genes and 2. based on detection of leukemia-specific surface antigens by flow-cytometry. The EWALL decided to focus on the first method since elaborated standards have already been defined by the ESGMRD- ALL (van der Velden 2007). The group agreed to adhere to these standards and the participating labs shall be involved in the lab rounds organised by the ESG-MRD-ALL . The next step is the definition of response criteria based on MRD for BCRABL negative and positive ALL . This is in line with considerations of the regulatory authorities in the US and Europe regarding the acceptance of new endpoints for clinical trials.
The collaboration of EWALL and ESGMRD- ALL will be intensified. During a meeting on MRD evaluation in Kiel (18.-20.9.2008) there will be a collaborative session dedicated to “ALL : Definition of remission and relapse in the era of flow and PCR”.