{'fraction_non_alphanumeric': 0.04922894424673784, 'fraction_numerical': 0.05753262158956109, 'mean_word_length': 5.294776119402985, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Comparison of CD20 expression in B‐cell lymphoma between newly diagnosed, untreated cases and those after rituximab treatment

Few studies have statistically investigated reduced CD20 expression in B‐cell lymphoma after rituximab therapy and genomic mutation of CD20 associated with reduction. We examined CD20‐positive rate in follicular lymphoma (FL) and diffuse large B‐cell lymphoma (DLBCL) by flow cytometry (FCM) and immunohistochemical staining (IHS), comparing 138 cases after rituximab therapy with 360 initial, not yet treated cases. Sequence analysis of exons 3 to 8 of CD20 was performed on 22 cases with low CD20‐positive rate after rituximab treatment. The results showed a statistical correlation between CD20‐positive rate in FCM and IHS. By FCM, the CD20‐positive rate among post‐rituximab cases was significantly lower than among initial cases in DLBCL, non‐germinal center origin B‐cell type (average values [avg] 57.8 and 87.9, respectively) (P < 0.0001), FL2 (avg, 93.9; 103.2) (P = 0.0083), and FL3A (avg, 90.6; 100.7) (P = 0.033). Stratified analyses of post‐rituximab cases showed significantly lower CD20‐positive rate in cases that were resistant at the start of the treatment and cases with progressive disease during rituximab therapy before biopsy. Sequence analysis showed silent mutation of exon 4 (632 C/T) in seven cases, although this number was not statistically significant. These results suggest the influence of B‐lymphoma subtype and a therapeutic effect before biopsy on CD20 expression at relapse and contribute to a better therapeutic approach for relapse cases after rituximab therapy. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02307.x, 2012)