Molecular study of complete remission in chronic lymphoprolipherative disorders after first line fludarabine therapy

The introduction of the new purine analogues has opened new prospectives of treatment for chronic lymphoproliferative disorders We tested Fludarabine ( 30 mg/m2 for 5 days monthly, 8 courses )as single agent as first line treatment in 32 high risk chronic B-lymphoprolipherative diseases Ten patients achieved true Complete Response and 2 B-CLL obtained a nodular CR. Nine patients with true CR who fiillfilled also the criteria of complete immunophenotypic response were studied at molecular level. Nodular CR were not considered to this aim. Since immunoglobulin heavy chain (IgH) gene rearrangement occurs at an early stage of B-lymphocyte development it can be exploited as a marker for clonality in the vast majority of B lymphoid malignancy. In order to improve the sensibility of IgH PCR strategies we performed a full nested PCR; briefly we performed a first amplification round using as external primer a mixture of Vh family specific oligonucleotides (sense) and an oligonucleotide specific to the external portion of I common region (ami sense), followed by a nested round amplification, based on the use of FR2 or FR3 complementary primers and an internal JH primer. This PCR strategy was successfull in 8 out of 9 cases. A dilution experiment showed a sensibility of 5 x 10 All the patients studied at the molecular level were positive for the presence of the signal of the neoplastic clone The significance of the persistence at molecular level of residual clonal population in clinical postchemotherapy remission remains to be clarify, because its role in determining relapse is still unclear and the relationship with the immunocompetent cell surveillance must be better analyzed To this aim we think that the possibility to obtain a quantification of the PCR product could be really determinant to give a prognostic value to the monitoring during the follow up of the disease.