Blinatumomab (Blina) and inotuzumab (InO) have improved the outcome of relapsed/refractory B-lymphoblastic leukemia (R/R B-ALL). However, many patients (pts) relapse after these treatments and little is known on their outcomes after recurrence and re-treatment with subsequent immunotherapy. We hereby describe the clinical characteristics and outcome of 71 pts with R/R B-ALL treated with both Blina and InO in any sequence - Blina/InO or InO/Blina - at different disease recurrences. At diagnosis, the median age was 34 years (15-64) and the male/female ratio was 1.6. Sixteen pts (22%) were Ph+ ALL, 3 (4%) were t(4;11)+ and 9 (13%) carried a complex karyotypes. ECOG PS was 0-1 in 66 pts (93%).

At the time of the first immunotherapy, pts had received a median of 2 previous lines of treatment (1-8). All Ph- pts received intensive chemotherapy front-line; Ph+ pts received TKIs and steroids in 13 cases and intensive chemotherapy plus TKIs in 3 cases. Blina was the first salvage treatment (Blino/InO sequence) in 57 pts (80%) and InO (InO/Blina sequence) in 14 (20%). Twenty-seven pts (38%) had underwent a previous allogeneic hematopoietic stem cell transplantation (HSCT). At the start of Blina as first immunotherapy, the median bone marrow (BM) blast count was 40% (0-100%); at the start of InO as first immunotherapy, the median BM blast count was 64% (2-90%). An extramedullary involvement was present in 5 patients (9%) in the Blina/InO group and in 1 patients (7%) in the InO/Blina group. During immunotherapy, the median number of lumbar punctures was 2 (0-9). A median of 2 cycles were administered for both Blina (range 1-9) and Ino (range 1-4). In the Blina/InO group, after Blina a G3/4 toxicity occurred in 15 cases (26%): non-hematologic in 12 cases (21%), neurologic in 6 (8%). Infections occurred in 17 pts (30%). In the InO/Blina group, after InO a G3/4 toxicity occurred in 3 pts (21%), with extra-hematologic toxicity in 2 cases (14%, liver toxicity 1 case). Infections occurred in 4 cases (28%). In the Blina/InO group, after Blina 36 pts (63%) achieved a complete remission (CR), with a negative minimal residual disease (MRD) in 24 (42%) pts; after InO, a CR was re-achieved in 47 pts (82.4%), with 34 (59.6%) being MRD-.

In the InO/Blina group, after InO a CR was reached in 13 cases (93%), with 6 pts (42.8%) being MRD-; after Blina, a CR was re-achieved in 6 pts (42.8%), with 3 (21.4%) being MRD-.

This salvage immunotherapy strategy represented a bridge to alloHSCT for 26 pts (37%).

From the first immunotherapy, in the Blina/InO group, the median overall survival (OS) was 19 months and after InO 6.3 months (OS in MRD- vs MRD+, p ns). Disease free survival (DFS) after Blina was 7.4 months (11.6 vs 2.7 months in MRD- vs MRD+ pts, p .03) and after InO it was 5.4 months (MRD- vs MRD+ pts, p ns).

In the InO/Blina group, the median OS was 9.4 months and after Blina 4.6 months (7.5 vs 2.8 months in MRD- vs MRD+ pts, p .02). DFS after InO was 5.1 months (MRD- vs MRD+ pts, p ns) and after Blina it was 1.5 months (8.7 vs 2.5 gg in MRD- vs MRD+ pts, p .02).

OS and DFS in MRD- pts after Blina was significantly better, both in the Blina/InO and the InO/Blina groups.

With a median follow-up of 16.5 months from the start of immunotherapy and 33.8 months from initial diagnosis, 24 pts (34%) are alive and 16 (22%) are alive in CR. Four patients (6%) died in CR due to veno-occlusive disease during HSCT after InO treatment. Interestingly, OS and DFS from the first immunotherapy was better in pts with a previous alloHSCT (median survival 24.2 vs 13 months, p=.0135). AlloHSCT after second immunotherapy was associated with a better OS and DFS (OS 9.8 and DFS 7.2 months vs 7.8 and 4.4 months, p ns).

Our real-life study in R/R B-cell ALL pts with multiple previous lines of treatment demonstrates the feasibility and efficacy of a sequential immunotherapy strategy in terms of MRD response, DFS and OS, and as a bridge to HSCT.

SM and PC: equal contributors

Disclosures

Papayannidis: Janssen: Honoraria; Astellas: Honoraria; AbbVie: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Curti: Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Chiaretti: amgen: Consultancy; pfizer: Consultancy; novartis: Consultancy; Incyte: Consultancy. Forghieri: Jannsen: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Jazz: Honoraria. Bonifacio: Bristol Myers Squibb: Honoraria; Amgen: Honoraria; Novartis: Honoraria; Pfizer: Honoraria. Cerrano: Janssen: Honoraria; Insight: Honoraria; Jazz: Honoraria. Fracchiolla: Gilead: Honoraria, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

© 2021 by The American Society of Hematology
2021
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