Molecular response assessed by PCR is the most important factor predicting failure-free survival in indolent follicular lymphoma: update of the MDACC series.

BACKGROUND We have observed that molecular response, as defined by a PCR-negative status during the first year of therapy, along with beta 2-microglobulin (beta 2M), was the most important variable associated with failure-free survival (FFS) in follicular lymphoma (FL). Herein, we present an update of the previously published MDACC series. PATIENTS AND METHODS A total of 116 patients (male:female ratio 64:52; median age: 52 years) with indolent FL and BCL-2 rearrangement (at MBR or mcr breakpoints) assessable in peripheral blood (pb) by PCR prior to treatment, and with two or more PCR determinations during the first year, were selected for the present study. RESULTS Of the 116 patients, 4 who presented with progression and 1 who died of unrelated causes during the first year were excluded from the landmark analysis. One hundred patients (86%) achieved clinical CR and 80 (69%) achieved a negative PCR status within first year. Median FFS was 6.4 years. Five-year FFS was 73% and 28% for molecular responders and nonresponders, respectively (P = 0.001). In spite of this strikingly higher FFS favoring molecular responders, no clearcut plateau was evident in this group. Molecular response assessed in pb (P = 0.001) and serum beta 2M (P < 0.001) were the most important factors to predict FFS in the multivariate analysis. In the subset of patients with normal beta 2M and molecular CR, there was a trend for a plateau in the FFS curve. No significant difference between the groups has been observed so far in terms of survival. CONCLUSIONS Molecular response assessed in pb using a PCR technique is, along with beta 2M, the most important factor to predict FFS in FL.