The effect of blinatumomab prior to allo-HSCT in adult patients with B-ALL

Adult patients with acute lymphoblastic leukemia (ALL) have a poor prognosis, and 5-year overall survival (OS) in adults aged >50 years is 20%. Blinatumomab has shown efficacy in patients with relapsed/refractory B-cell ALL (B-ALL) and has achieved minimal residual negativity; however, there are limited data on the impact of pretransplant blinatumomab in adults.

Here, we summarize a retrospective study on the effect of blinatumomab prior to allogeneic stem cell transplantation (allo-HSCT) in adult patients with B-ALL, published by Sayyed et al.¹ in Transplantation and Cellular Therapy.

Study design¹

• This retrospective study included adult patients with B-ALL who underwent allo-HSCT at the Princess Margaret Hospital, Toronto, CA, between January 2010 and December 2021.
• The study endpoints included OS, cumulative incidence of relapse, non-relapse mortality (NRM), and graft-versus-host disease and relapse-free survival (GRFS).

Key findings¹

Patient baseline characteristics

• A total of 117 patients were included in the analysis, of which 31 patients received blinatumomab before allo-HSCT
• Key baseline characteristics differed between the two cohorts, as summarized in Table 1

Table 1. Patient baseline characteristics*

Characteristic, %	Overall (N = 117)	Blinatumomab (n = 31)	No blinatumomab (n = 86)	p value
GvHD, graft-versus-host disease; MRD, minimal residual disease; Ph, Philadelphia chromosome; PTCy, post-transplant cyclophosphamide *Adapted from Sayyed, et al.1
Diagnosis				p = 0.01
Ph-negative	57.3	77.4	50
Ph-positive	42.7	22.6	50
Disease-risk index				p < 0.001
Intermediate	68.4	35.5	80.2
High	30.8	61.3	19.8
Very high	0.8	3.2	0
Indication for transplant				p < 0.001
Relapse	29.9	54.8	20.9
Primary induction failure	16.2	41.9	7.0
Chemotherapy intolerance	2.7	0	3.5
High-risk features	39.3	0	53.5
Therapy-related	8.5	3.2	10.5
MRD positivity after               chemotherapy	3.4	0	4.7
Dual T-cell depletion				p = 0.005
Yes	39.3	61.3	31.4
No	60.7	38.7	68.6
PTCy-based GVHD prophylaxis				p < 0.001
Yes	45.3	80.6	32.6
No	54.7	19.4	67.4
Lines of treatment before transplant				p < 0.001
1	49.6	0	67.4
2	41.0	64.5	32.6
3	7.7	29.0	0
4	1.7	6.5	0
Year of transplant				p < 0.001
2010–2015	72	57	95
2016–2021	15	22	5

Survival and relapse outcomes

• After a median follow-up of 36 months,
  • 2-year OS, GRFS, and the cumulative incidence of relapse was significantly higher in patients who received blinatumomab vs those who did not (Figure 1); and
  • the 2-year NRM and Grade 2–4/Grade 3−4 acute graft-versus-host disease at Day 100 was significantly lower in patients who received blinatumomab prior to allo-HSCT versus those who did not (Figure 1).
• The incidence of Grade 2−4 and Grade 3−4 acute graft-versus-host disease in the total cohort was 48.9% and 27.8%, respectively.
• Multivariate analysis revealed a significant association between pretransplant blinatumomab and improved OS and NRM.

aGvHD, acute graft-versus-host disease; CIR, cumulative incidence of relapse; GRFS, GvHD-free and relapse-free survival; NRM, non-relapse mortality; OS, overall survival
*Data from Sayyed, et al.¹

 

Key learnings
Despite the small sample size, blinatumomab prior to allo-HSCT was associated with improved OS and reduced NRM in adult patients with B-ALL Larger prospective studies are needed to confirm these findings