LOCALIZED FOLLICULAR LYMPHOMA: SPREAD OF Bcl-2/IgH+ CELLS IN THE BLOOD AND BONE MARROW FROM THE PRIMARY SITE OF DISEASE AND POSSIBILITY OF CLEARANCE AFTER INVOLVED FIELD RADIOTHERAPYPROGNOSTIC. Pulsoni A, ¹Della Starza I, ¹Frattarelli N, ¹Ghia E, ²Carlotti E, ¹ Cavalieri E, ¹Matturro A, ¹Tempera S, ²Rambaldi A, ¹Foà R Pulsoni A, ¹Della Starza I, ¹Frattarelli N, ¹Ghia E, ²Carlotti E, ¹ Cavalieri E, ¹Matturro A, ¹Tempera S, ²Rambaldi A, ¹Foà R 1 Division of Hematology, Dipartimento di Biotecnologie Cellulari ed Ematologia, “La Sapienza” University, Rome, Italy and 2 Division of Hematology, Ospedali Riuniti di Bergamo, Italy BACKGROUND Localized forms of follicular lymphoma (FL) have a good prognosis being curable in 40-50% of cases with local radiotherapy alone. Polymerase chain reaction (PCR) of Bcl-2/IgH rearranged cells provides a sensitive measure of peripheral blood (PB) and bone marrow (BM) minimal non-Hodgkin’s lymphoma (NHL) cell contamination in FL. Aims of the study: To evaluate whether a more sensitive technique could document the presence of circulating NHL cells in limited stage FL and the possibility of inducing the disappearance of PCR+ cells from the PB and BM after involved field radiotherapy. PATIENTS AND METHODS Between April 2000 and April 2006, 24 consecutive patients with FL, Ann-Arbor stage I or IIA, entered the study. Median age was 57 years (range: 27-74), with 9 males and 15 females.(Table 1) Involved field radiotherapy was performed in all patients. PCR was evaluated in the BM and PB of all patients at diagnosis and was re- evaluated 3 months after treatment and, thereafter, every 6 months (Table 2). RESULTS PCR analysis performed at presentation demonstrated the presence of Bcl-2/IgH+ cells in the PB and/or BM of 16 of the 24 patients studied (66.6%). The rearrangement fell in the major breakpoint region (MBR) in 15 cases and in the minor cluster region (mcr) in 1. Cases Bcl-2/IgH negative at baseline were all negative for JH rearrangement. Of the 16 Bcl-2 positive patients at baseline, at least one post- treatment molecular evaluation was performed in 15 (1 patient refused). Among these evaluable patients, 9 (60%) achieved a PCR negativity in the PB and BM, while 6 (40%) remained positive. RQ-PCR could be performed on the baseline material of 7 Bcl-2/IgH positive cases. The molecular clearance of BCL2/IgH+ cells occurred, following therapy, only in the 3 patients who at diagnosis had a PB or BM tumor infiltration lower than 1 positive cell/100,000. Conversely, the 4 patients with a higher tumour contamination (1 positive cell in 10,000 or more) remained PCR positive after irradiation and 2 patients ultimately relapsed(Table 3). After treatment, all patients achieved a clinical complete remission (CR) that still holds, except for 2 persistently Bcl-2 positive patients who had a clinical relapse 39 and 9 months after treatment, and 1 patient who obtained a PCR negativity but relapsed 36 months after diagnosis. The follow-up ranged from 11 to 70 months (median 43.5). Among the 6 patients persistently positive for Bcl-2/IgH rearranged cells in the BM and/or PB after treatment, 2 (33.3%) have relapsed, while among the 17 patients negative either at baseline or after treatment only 1 (5.8%) has so far relapsed CONCLUSION Polymerase chain reaction analysis for Bcl-2/IgH rearranged cells revealed the presence of viable lymphoma cells in the PB and/or BM of the majority of patient with FL considered in stage I/II by conventional staging procedures.Polymerase chain reaction analysis for Bcl-2/IgH rearranged cells revealed the presence of viable lymphoma cells in the PB and/or BM of the majority of patient with FL considered in stage I/II by conventional staging procedures. In most FL patients with Bcl-2/IgH+ cells in the PB and/or BM prior to treatment, pathological cells were cleared following involved field radiotherapy. As a consequence of the elimination of the primary focus, PB and BM contamination disappeared in the majority of our patients, persisting only in a minority of cases.In most FL patients with Bcl-2/IgH+ cells in the PB and/or BM prior to treatment, pathological cells were cleared following involved field radiotherapy. As a consequence of the elimination of the primary focus, PB and BM contamination disappeared in the majority of our patients, persisting only in a minority of cases. Quantitative RQ-PCR demonstrated the molecular clearance of BCL2/IgH+ cells following radiotherapy, in patients who had a very low PB or BM tumour infiltration at diagnosis. On the contrary, patients with a higher tumour contamination (one positive cell in or more) invariably remained PCR positive after irradiation and two of them ultimately relapsed.Quantitative RQ-PCR demonstrated the molecular clearance of BCL2/IgH+ cells following radiotherapy, in patients who had a very low PB or BM tumour infiltration at diagnosis. On the contrary, patients with a higher tumour contamination (one positive cell in or more) invariably remained PCR positive after irradiation and two of them ultimately relapsed. The possibility of a persistent lymphoma cell clearance is proportional to the amount of cells detected at presentation by quantitative PCR.