Updated Clinical Activity of Graspa Versus Native l-Asparaginase in Combination with Cooprall Regimen in Phase 3 Randomized Trial in Patients with Relapsed Acute Lymphoblastic Leukemia (NCT01518517)

Background

Asparaginase is a cornerstone in the treatment of ALL, but its utility is limited by toxicities including hypersensitivity. Clinical allergy is associated with inactivation of asparaginase by antibodies, which can also neutralize asparaginase without any clinical signs of hypersensitivity (silent inactivation). GRASPA (proposed eryaspase, E-ColiL-Asparaginase encapsulated into red blood cells) improves pharmacokinetics, tolerability and maintain circulating asparaginase (ASPA) activity due to the protective barrier of the erythrocyte membrane.

In a recent Phase III trial, it has shown to prolong the asparaginase activity and significantly reduce the incidence of allergic reactions in pts with relapsed ALL.

In the non-allergic pts, GRASPA significantly reduced the incidence of hypersensitivity (0% vs 46%; p<0.001). ASPA activity >100 IU/l was 21 ± 5 vs 9 ± 7 days in GRASPA and L-ASP, respectively (p<0.001).

Methods

This open, randomized international Phase 3 study enrolled pts with relapsed ALL. The co-primary endpoints were the duration of ASPA activity > 100IU/L and the incidence of hypersensitivity during induction. Key secondary endpoints were complete remission, minimal residual disease, relapse rate, event free survival (EFS) and overall survival (OS). Pts (n=80), aged 1-55 years without prior hypersensitivity were randomized to GRASPA (150 IU/kg, n=26, Arm A) or native L-asparaginase (L-ASP, 10,000 IU/m², n= 28, Arm B). Additionally, 26 pts with prior hypersensitivity were treated with GRASPA in a single stratum (Arm C). All pts received COOPRALL protocol as a backbone chemotherapy.

Results

A total of 80 pts with relapsed and or refractory ALL were enrolled into the trial. There were a greater proportion of pts who completed the induction treatment in GRASPA arm (65%) than in the L-ASP arm (46%). The main reasons for treatment discontinuation were: target levels of asparagine depletion not reached (64%) in GRASPA arm, and adverse events (58%) in the L-ASP arm. In addition, in the L-ASP arm, 5 (19%) pts prematurely discontinued treatment due to disease progression. As of the cut-off date (28^thAugust 2014), the majority of pts (63%) still continued in the study and followed-up for survival. The relapse rate at 6 and 12 mo was low, and accounted for 3 (13%; 95% CI: 2.6; 32.4) and 5 (26%; 95% CI: 9.1; 51.2) in the GRASPA arm, compared to 1 pt (5%) and 3 (17%; 95% CI: 3.6; 41.4) in the L-ASP arm, respectively. Except for L-ASP, and adult patients, the median EFS and OS were not reached for GRASPA in the entire set or in children, either at 12 months. Overall, there was a trend across all groups with lower EFS and OS event rates with GRASPA compared to L-ASP, as presented in table below. The 2-year follow up will be additionally provided at the meeting

 

	GRASPA vs L-ASP
	All patients GRASPA = 26 L-ASP = 28	Children GRASPA = 21 L-ASP =  21	Adults GRASPA = 5 L-ASP = 7
12 mo EFS
Median (mo)	NR vs 11.6	NR	4.6 vs 1.6
Events	30.8% vs 50.0%	19.1% vs 38.1%	80% vs 85.7%
HR	0.54	0.47	0.69
95% CI	0.23; 1.26	0.15; 1.47	0.20; 2.44
P Value*	0.153	0.196	0.569
12 mo OS
Median (mo)	NR	NR	10 vs 8.2
Events	23.1% vs 32.1%	4.8% vs 14.3%	20% vs 42.8%
HR	0.63	0.34	0.39
95% CI	023; 1.74	0.05; 2.42	0.05; 2.81
P Value*	0.377	0.424	0.705

* P value in all subsets is not statistically significant

Conclusion

GRASPA has demonstrated both safety and activity in pts with relapsed ALL, and provides an alternative treatment option for those patients.