Prognostic Factors for Outcome in Patients (pts) with Refractory and Relapsed Acute Lymphocytic Leukemia (ALL) Treated with Inotuzumab Ozogamicin (IO), a CD22 Monoclonal Antibody
Authors: Jabbour Elias , O'Brien Susan , Sasaki Koji , Huang Xuelin , Thomas Deborah A. , Rytting Michael E. , Garcia-Manero Guillermo , Cortes Jorge E. , Sherry Pierce , Kadia Tapan M. , Hagop Kantarjian 
Published: October 2019

Background:

IO was found to be highly active in pts with refractory-relapsed ALL, with an overall response rate of 58% and a median survival of 6.3 months (mos). Identifying factors associated with different outcomes on IO therapy may help select patients for this treatment and advice of prognosis.

Methods:

A total of 89 pts treated with IO on previous studies were analyzed. IO was given at 1.3-1.8 mg/m2 IV x 1 every 3-4 weeks or weekly (0.8 mg/m2 Day 1, 0.5 mg/m2 Days 8 and 15) every 3-4 weeks. Pretreatment factors associated with achieving marrow complete response (CR) and with survival were analyzed using standard statistical methods.

Results:

Baseline characteristics of the 89 pts are summarized in Table 1. Overall, 17 pts (19%) achieved CR, 29 (33%) had CRp, and 6 pts (7%) had bone marrow CR with incomplete recovery (Cri). 5 pts (6%) died within 4 weeks of starting therapy. The ORR was 58%. The rate of cytogenetic CR by morphologic responses was as follows: 8 cytogenetic CR/10 morphologic CR (80%); 16 cytogenetic CR/22 morphologic CRp (73%); and 4 cytogenetic CR/4 morphologic CRi (100%). The median survival of patients with at least marrow CR was 9 mos versus 3.4 mos for those without marrow CR (p<0.001). By multivariate analysis, a high peripheral blood absolute blast count (ABC) and low platelet count were independently associated with a lower likelihood of achieving at least marrow CR. With a median follow-up of 23 mos, (5-44), the median overall survival of pts who received IO was 6 mos; the median survival was 5 mos with the single-dose schedule and 9.5 mos with the weekly schedule. The median remission duration was 12 mos (1-year rate, 48%) (Figure 1A). Baseline characteristics independently associated with worse survival included adverse cytogenetics [complex karyotype, translocation (4;11), translocation (9;22), abnormal chromosome 17], disease beyond first salvage, and high peripheral blood ABC. Pts with 0, 1-2 or 3 adverse factors had a median survival of 42+, 7.5, and 2.4 mos, respectively (Figure 1B). To assess the benefit of achieving a marrow CR, we repeated the multivariate survival analysis using a 6-week landmark that excluded 5 pts who died within 6 weeks. The median survival was 9.2 mos and 3.4 mos for patients with and without marrow CR (p<0.001). The multivariate analysis selected the achievement of response as independently associated with survival improvement [HR=0.5 (95% CI=0.28-0.89); p=0.02]. Disease with complex karyotype, translocation (4;11), translocation (9;22), and abnormal chromosome 17 [HR=2.9 (95% CI=1.29-6.62); p=0.009], and disease status beyond first Salvage regimen [HR=1.2 (95% CI=2.16-3.91); p=0.01] were independently associated with significant worse survival. Pts with 0, 1- 2 or 3 adverse factors had a median survival of 42+, 8, and 3 mos, respectively (Figure 1C).

Conclusion:

Our current analyses identified a subset of adult pts with ALL in whom outcome of therapy with IO can be differentially predicted.

Table 1. Patients' characteristics N (%) Parameter Single-Dose, n=49 Weekly, n=40 Overall, n=89 Age, year ≤18 3 (6) 3 (8) 6 (7) ≥60 12 (24) 13 (33) 25 (28) ECOG, PS 0-1 44 (90) 36 (90) 80 (90) ≥2 5 (10) 4 (10) 9 (10) Salvage Status S1 13 (27) 16 (40) 29 (33) >S1 36 (73) 24 (60) 60 (67) PB ABC, x 109/L <1.0 33 (67) 25 (63) 58 (65) ≥1.0 16 (33) 15 (38) 31 (35) WBC, x 109/L <4.0 28 (57) 17 (43) 45 (51) 4-11 11 (22) 16 (40) 27 (30) >11 10 (20) 7 (18) 17 (19) BM blasts, % <20 3 (6) 8 (20) 11 (12) 20-49 10 (20) 8 (20) 18 (20) 50-69 8 (16) 6 (15) 14 (16) ≥70 28 (57) 18 (45) 46 (52) Platelets, x 109/L <100 43 (88) 28 (70) 71 (80) ≥100 6 (12) 12 (30) 18 (20) Karyotype Diploid 8 (16) 9 (23) 17 (19) Ph-positive 9 (18) 8 (20) 17 (19) Translocation (4;11) 6 (12) 3 (8) 9 (10) Complex 13 (27) 11 (28) 24 (27) Abnormal chromosome 17 6 (12) 5 (13) 11 (12) Other 6 (12) 4 (10) 10 (11) Prior ASCT 7 (14) 2 (5) 9 (10) Prior HCVAD regimen 35 (71) 32 (80) 67 (75) CD22-positive, % ≥90 28 (57) 31 (78) 59 (66) 70-89 14 (29) 7 (18) 21 (24) 50-69 7 (14) 2 (5) 9 (10)

Figure 1A: Survival and response duration for the whole population Figure 1A:. Survival and response duration for the whole population

Figure 1B: Survival by risk score according to baseline adverse factors Figure 1B:. Survival by risk score according to baseline adverse factors

Figure 1C: Survival by risk score according to a landmark analysis taking into account response as an additional variable Figure 1C:. Survival by risk score according to a landmark analysis taking into account response as an additional variable

Disclosures

Kadia: GSK: Research Funding; ARIAD: Honoraria. Hagop:ARIAD: Research Funding; Pfizer: Research Funding; Amgen: Research Funding.