Efficacy and safety of yttrium-90 ibritumomab tiuxetan in Japanese patients with non-Hodgkin lymphoma

Real-world data from yttrium-90 ibritumomab tiuxetan treatment of relapsed or refractory indolent B-cell non-Hodgkin's lymphoma: J3Zi Study

Yttrium-90 ibritumomab tiuxetan (90YIT) is a radioimmunotherapy agent in which the radioisotope yttrium-90 is bound to ibritumomab via tiuxetan as a chelating agent, and is used for relapsed or refractory low-grade B-cell non-Hodgkin's lymphoma (rr-B-NHL). We conducted a joint study to evaluate the clinical outcome of 90YIT. The J3Zi study is composed of data from patients receiving 90YIT for rr-B-NHL from the top three institutions with 10 years of 90YIT treatment experience from October 2008 to May 2018 in Japan. The efficacy, prognostic factors and safety of 90YIT were retrospectively evaluated. Data from 316 patients were analyzed; the mean age was 64.6 years and the median number of prior treatments was 2. The median PFS was 3.0 years, the final OS rate was over 60%, and the median OS was not reached during the study period. Significant factors influencing PFS were sIL-2R ≤ 500 (U/mL) and no disease progression within 24 months of first treatment. Significant factors influencing OS were number of prior treatments ≤ 2 and sIL-2R ≤ 500 (U/mL). The PFS and OS rates were found to be significantly higher in the late half era (2013 to 2018) than in the early half era (2008 to 2013) during the study period. Prognosis following 90YIT treatment was improved in the late half era compared to the early half era. As treatment using 90YIT increased, administration of 90YIT shifted to the earlier treatment line. This may have contributed to the improvement of prognosis found in the late era. (UMIN000037105).

Does tumoral (111)In-ibritumomab accumulation correlate with therapeutic effect and outcome in relapsed or refractory low-grade B-cell lymphoma patients undergoing (90)Y-ibritumomab radioimmunotherapy?

OBJECTIVES

The aim of this study was to determine whether tumoral (111)In-ibritumomab accumulation on pre-treatment imaging correlates with therapeutic responses and progression-free survival (PFS) in patients with non-Hodgkin's lymphoma (NHL) undergoing (90)Y-ibritumomab radioimmunotherapy (RIT).

METHODS

This was a retrospective study of 39 patients with low-grade B-cell NHL treated with RIT. We classified the patients into positive and negative groups according to the presence or absence of tumoral (111)In-ibritumomab accumulation on pre-treatment (111)In-ibritumomab examinations. We then determined the correlation between the (111)In-ibritumomab imaging findings and the patients' therapeutic responses and PFS.

RESULTS

Tumoral (111)In-ibritumomab accumulation was positive in 64.1% and negative in 35.9% of the patients. The (111)In-positive patients had a significantly higher overall response rate (ORR) compared to the (111)In-negative patients (100.0% vs. 78.6%, p = 0.02). The (111)In-negative patients with advanced disease (stages III/IV) had a significantly lower ORR (40%) and a significantly higher rate of progressive disease (40.0%) compared to those of the (111)In-negative patients with limited disease (stages I/II) (100% and 0%, p = 0.009 each). However, these two groups had similar 2-year PFS rates (65.0% vs. 50.0%, p = 0.80).

CONCLUSIONS

(111)In-ibritumomab imaging findings seem to correlate with ORR and the progressive disease rate after RIT, but not with PFS.

KEY POINTS

All 39 NHL patients had tumoral accumulation on pretreatment FDG-PET/CT. 64.1% of NHL patients had tumoral accumulation on a pretreatment (111) In-ibritumomab examination. (90) Y-ibritumomab RIT resulted in high overall response and complete remission rates. (111) In-ibritumomab avidity of lymphoma lesions could predict a strong therapeutic effect. (111) In-ibritumomab imaging findings did not correlate with progression-free survival.