Absence of High-Dose Consolidation Courses and Low Numbers of Allogeneic HSCTs Did Not Affect Overall Optimistic Results in B-Cell Precursor Ph-Negative Adult ALL Patients Treated By Non-Intensive but Non-Interruptive ALL-2009 Protocol: Data of the Russian ALL Study Group

Introduction

It is postulated that the improvement in the overall treatment outcome in adult Ph-negative ALL came from the implementation of more aggressive pediatric-like protocols and higher portion of allogeneic HSCT. Here we report the results of the adult (15-55 yy) Ph-negative ALL protocol based on the opposite approaches: less intensive but non-interruptive treatment with low numbers of allo-HSCT. The study is registered on the ClinicalTrials.gov public site; NCT01193933.

Patients and Methods

The ALL-2009 is based on: (1) the replacement of prednisolone (Pdn) 60 mg/m² with dexamethazone (Dexa) 10 mg/m² if blast cells are >25% in b/m after prephase (7d); (2) de-intensified but non-interruptive 5 months induction/consolidation treatment (5 wks prd/dexa with 3 instead of 4 dauno/vncr pulses, 4 weeks of 6MP with 5 L-asp, 2 instead of 4 ARA-C blocks, 1 instead of 2 Cph injections during induction; induction-like 3 consolidations for 3wks, 2wks, 4wks-continuously without intervals), followed by (3) 2 late (at 6 mo) intensifications- with 1 day HD MTX and with 1 d HD ARA-C, both with L-asp and 3 ds dexa and (4) 2-yrs continuous 6MP/MTX maintenance with doses modification according to myelosuppression with monthly 3-days dexa/vncr/L-asp pulses (∑ L-asp = 590.000 IU/m²). The protocol was identical for all risk groups. Allo-HSCT was indicated only for extremely high-risk BCP-ALL (t(4;11),L>100). No central MRD monitoring was performed.

Since Apr 2009 till June 2015 20 centers had recruited 168 BCP-Ph-negative ALL pts with a median age 28 years (15-54), 84f/84 m. Full cytogenetics was available in 67,3% (n=113), 43,4% of them (n=49) had normal karyotype (NK), 10% (n=9%) had no mitosis, 47,6% (n=54) - different abnormalities (hypoploid-1, hyperploid-12, t(11q23)/MLL-8, del11q23-2, t(1;19)-2, t(12;21)-1;others-28). 26,7% of pts (n=45) were in the standard risk (SR) group (WBC <30, EGIL BII-III, LDH < 2N; no late CR; t(4;11)-negative), 56,5% (n=95) - in the high risk (HR) group (WBC >30; EGIL BI, LDH > 2N; late CR; t(4;11)-positive), 28 patients (n=16,8%) were not qualified by the risk. The analysis was performed in June 2015. 158 pts were available for analysis.

Results

CR rate in 158 available for analysis pts was 87,7% (n=139), induction death occurred in 9,1% (n=14), resistance was registered in 3,2% (n=5). The majority of CR pts (87,8%) achieved it after prephase (12,2%, n=17) and the 1^st phase of induction (75,6%, n=105). Late responders constituted 12,2% (n=17). Allogeneic BMT was performed only in 9 of 144 patients who survived induction (6,2%).

Totally 31 pts (22,3%) had relapsed. At 60 mo OS for the whole group constituted - 50%, DFS - 51.3%. In a univariate analysis among various risk factors (age <> 30y, initial risk group, WBC, LDH, immunophenotype, late response >35d, PRD resistance) age (>30 y) became statistically significant for OS, DFS and relapse probability (RP) (pic.1), abnormal karyotype - for DFS (30% vs 68%, p=0,04) and RP (42% vs 19%, p= 0,04). In a multivariate analysis no common risk factors were significant.

Conclusions

Our data demonstrate that the proposed treatment approach is rather effective. We believe that constant non-interruptive treatment without intensive highly myelosuppressive consolidation courses and high portion of allogeneic HSCT may become an alternative and reproducible approach in adult Ph-negative ALL, though we have to stress that it should be very strict compliance of the pts to the protocol. All pts, mostly from the region hospitals who refused prolonged and constant treatment (~5%), relapsed.

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