Abstract
7003 Background: Lumiliximab is an anti-CD23 monoclonal antibody that is being investigated for the treatment of relapsed B-cell CLL (BCLL). CD23 is a glycoprotein expressed on the majority of CLL B cells. In a previous study, lumiliximab monotherapy given weekly was well tolerated, achieved sustainable CD23 receptor occupancy and showed clinical activity. A Phase I/II, multicenter study was conducted to evaluate the safety and efficacy of lumiliximab in combination with fludarabine, cyclophosphamide, and rituximab (L + FCR) for patients (pts) with relapsed CD23+ BCLL. In addition, CD23 receptor occupancy on BCLL cells with L + FCR and possible effects of elevated serum CD23 were evaluated. Methods: Thirty-one pts with relapsed BCLL received either 375 mg/m2 (n=3) or 500 mg/m2 (n=28) of L+ FCR for up to six 28-day cycles. All pts completed treatment and follow-up is ongoing. A semi-quantitative flow cytometry method was used to measure CD23 receptor occupancy and serum CD23 levels were measured using an enzyme-linked immunosorbent assay. Results: Median age at study entry was 58 yrs, 71% had Rai Stage I/II, and median # of prior regimens was 2 (1- 10). Using NCI-WG criteria, overall response rate was 65%: complete response (CR) 52% and partial response13%. Five of the 8 pts with del(11q22.3) achieved CR. Based on median follow-up of 16.8 mos (1.5 - 37.6), KM estimated median progression-free survival (PFS) for all pts was 19.3 mos. Median PFS for all responders and CR pts were 23.4 mos and 30.4 mos, respectively. Twenty-three pts (74%) reported a Grade 3 or 4 event, similar to what has been previously reported with FCR. L + FCR has a comparable safety profile with no additional toxicity. At lumiliximab schedule used, CD23 receptor occupancy was sustained with no effects by elevated levels of serum CD23. Conclusions: These results suggest that L +FCR is an effective regimen for pts with relapsed B-CLL. L+FCR produced an impressive CR rate, an encouraging PFS and a similar safety profile to that of FCR. Monthly L + FCR achieved sustainable CD23 receptor occupancy on BCLL, which was not affected by elevated levels of serum CD23. A large, randomized, global study of L+ FCR vs FCR (LUCID) is ongoing to further evaluate the safety and efficacy of this regimen. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Biogen Idec Biogen Idec Biogen Idec
Published Version
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