Blinatumomab as salvage therapy in relapsed/refractory B-ALL

According to the final analysis of the RIALTO trial published in Blood advances.

The RIALTO trial (ClinicalTrials.gov Identifier: NCT02187354) recruited 110 patients with R/R B-ALL. The median patient age was 8.5 years (range: 0.4-17 years), 56.4% were male, 29.1% had recurrent genetic abnormalities, and 88.2% had at least 5% blasts initially.

Patients received blinatumomab as a continuous infusion over a 6-week cycle for a maximum of 5 cycles. Complete response (CR) patients could receive up to 3 cycles of consolidation.


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Patients who achieved CR after the first cycle could switch to allogeneic hematopoietic stem cell transplantation (allo-HSCT), and 58 patients ultimately underwent allo-HSCT.

Results

Overall, 68 patients (61.8%) achieved CR during the first 2 cycles of blinatumomab, and 57 patients (51.8%) achieved an MRD response.

The researchers noted that the likelihood of response was not affected by the presence of cytogenetic/molecular abnormalities. CRs with MRD responses were observed in 4 patients with constitutional trisomy 21, 4 with MLL rearrangements, 2 with t(9:22)/BCR-ABLand 2 patients with t(17;19)/TCF3-HLF.

After a median follow-up of 11.5 months, the median relapse-free survival (RFS) was 8.5 months in patients achieving CR during the first 2 cycles of blinatumomab. The median RFS was 8.0 months for MRD responders and 2.8 months for MRD non-responders.

Overall survival (OS) was censored at 18 months and median OS was 14.6 months overall. Median OS was not reached in MRD responders and was 9.3 months in MRD non-responders (relative risk [HR], 0.18; 95% CI, 0.08-0.39).

The estimated OS rate at 1 year was higher for patients who underwent allo-HSCT than for those who did not: 87% and 27%, respectively.

Treatment-related adverse events (TRAEs) occurred in 73.6% of patients and serious AERTs occurred in 19.1%. The rate of EITR leading to discontinuation of treatment was 3.6%. There were no fatal TRAEs.

One patient had grade 3 cytokine release syndrome (CRS) and 1 patient had grade 4 CRS. Grade 3 neurological events were reported in 4 patients, but there were no events neurological grade 4.

“Overall, data from patients enrolled in the RIALTO trial support the use of blinatumomab as rescue therapy in children with B-ALL R/R, including those with molecularly resistant disease” , the researchers concluded.

Disclosures: This research was supported by Amgen, Inc. Some study authors have disclosed affiliations with biotechnology, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

F Locatelli, G Zugmaier, N Mergen, et al. Blinatumomab in Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia in Children: Final Analysis of the RIALTO Expanded Access Study. Blood Adv. Published online February 8, 2022. doi:10.1182/bloodadvances.2021005579

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