COMPARISON OF STANDARD- AND LOW-DOSE RITUXIMAB IN PRIMARY IMMUNE THROMBOCYTOPENIA (ITP): DATA FROM THE UK ITP REGISTRY
Author(s): ,
Caitlin Gracie
Affiliations:
The ITP Registry,Queen Mary University,London,United Kingdom
,
Abbas Zaidi
Affiliations:
Clinical Haematology,Bartshealth NHS Trust,London,United Kingdom
,
Umesh Doobaree
Affiliations:
The ITP Registry,Queen Mary University,London,United Kingdom
,
Louise Taylor
Affiliations:
Clinical Haematology,Bartshealth NHS Trust,London,United Kingdom
,
Drew Provan
Affiliations:
Clinical Haematology,Bartshealth NHS Trust,London,United Kingdom
,
Adrian Newland
Affiliations:
Clinical Haematology,Bartshealth NHS Trust,London,United Kingdom
Vickie McDonald
Affiliations:
Clinical Haematology,Bartshealth NHS Trust,London,United Kingdom
(Abstract release date: 05/17/18) EHA Library. Gracie C. 06/15/18; 214599; S139
Caitlin Gracie
Caitlin Gracie
Contributions
Abstract

Abstract: S139

Type: Oral Presentation

Presentation during EHA23: On Friday, June 15, 2018 from 11:30 - 11:45

Location: Room A9

Background
Rituximab is reported to give response rates, partial or complete, (platelets >30 x10^9/L and >2 baseline) of up to 60% in patients with ITP. The efficacy of lower doses of rituximab (<375mg/m2) have been published successfully but there have been no large-scale comparative randomised trials.

Aims
To compare the efficacy of low and high dose rituximab in patients with primary ITP.

Methods
We performed a retrospective review of the efficacy of two main dosing regimens in ITP patients (100mg weekly x 4 weeks (low dose) vs 375mg/m2 weekly x 4 weeks (standard dose)) using data from the UK Adult ITP registry, a large national registry of primary ITP. Choice of dosing was based on physician preference and funding.

Results
The UK Adult ITP registry database was reviewed for all patients who received rituximab. There were 301 patients who had sufficient data input for analysis. Of these 301 patients, 179 had received low dose rituximab dose and 122 had received standard dose. There was no significant difference in the demographics between the two groups: (female 56% and 46% respectively; median age of 56.6years and 56.4 years respectively). 10% patients in the low dose group and 17% in the high dose group underwent splenectomy prior to receiving rituximab and the average number of courses of treatments given before rituximab was 6 in both groups (including corticosteroids and intravenous immunoglobulin). The median time from diagnosis to rituximab therapy in the low dose group was 13.7 months and in the standard dose group was 14.4 months. There was no difference in the median patient platelet count before treatment between the groups (28.1 and 26.4 x10^9/L respectively for low dose and standard doss regimes). The median platelet count was not significantly different at 2, 4 and 6 months after rituximab therapy between the low and standard doses (46, 72, 74 x10^9/L and 43, 65, 81 x10^9/L respectively). There was, however, some ongoing increase in platelet count between 2 and 4 months for both dosing schedules showing ongoing delayed response. At 2 months after therapy, complete remission (defined as platelets >100 x 10^9/L) was achieved in 21.1% and 32% patients in the low dose and standard dose regimes respectively. This increased to 37.7% and 43.1% at 6 months. Partial remission at 2 months was achieved in 36 and 27.1% patients for 100mg and 375mg/m2 doses. By 6 months this was 34% and 27% respectively. Bleeding episodes (all bleeds) before and after therapy were reported in 63.7% and 44.7% of patients in the 100mg dose group and 63.9% and 39.3% patients in the 375mg/m2 group. The median number of bleeding events per patient prior to treatment was 2 in both groups (range 0-4). After rituximab the median was 1 in both groups (range 0-2). For those that did bleed, the median time was 4.0 months for 100mg (range 1.6 – 18.7) and 2.8 months for 375mg/m2 (range 1.1 – 12.3). There was no statistically significant difference between these two. For those that required another line of treatment, the median time was 4 months for 100mg and 3 months for the 375mg/m2 dose.

Conclusion
In conclusion, in this large cohort, 100mg rituximab appears to be as effective as 375mg/m2 in improving platelet count and achieving PR. These data show that both doses are equally as effective in reducing bleeds with no difference in the median time to next treatment. This would suggest, that for patients with primary ITP, 100mg rituximab weekly x 4 weeks may be a  more cost-effective option than the standard dosing regimen (375mg/m2 weekly x 4).

Session topic: 33.  Platelets disorders

Keyword(s): Immune thrombocytopenia (ITP), Rituximab

Abstract: S139

Type: Oral Presentation

Presentation during EHA23: On Friday, June 15, 2018 from 11:30 - 11:45

Location: Room A9

Background
Rituximab is reported to give response rates, partial or complete, (platelets >30 x10^9/L and >2 baseline) of up to 60% in patients with ITP. The efficacy of lower doses of rituximab (<375mg/m2) have been published successfully but there have been no large-scale comparative randomised trials.

Aims
To compare the efficacy of low and high dose rituximab in patients with primary ITP.

Methods
We performed a retrospective review of the efficacy of two main dosing regimens in ITP patients (100mg weekly x 4 weeks (low dose) vs 375mg/m2 weekly x 4 weeks (standard dose)) using data from the UK Adult ITP registry, a large national registry of primary ITP. Choice of dosing was based on physician preference and funding.

Results
The UK Adult ITP registry database was reviewed for all patients who received rituximab. There were 301 patients who had sufficient data input for analysis. Of these 301 patients, 179 had received low dose rituximab dose and 122 had received standard dose. There was no significant difference in the demographics between the two groups: (female 56% and 46% respectively; median age of 56.6years and 56.4 years respectively). 10% patients in the low dose group and 17% in the high dose group underwent splenectomy prior to receiving rituximab and the average number of courses of treatments given before rituximab was 6 in both groups (including corticosteroids and intravenous immunoglobulin). The median time from diagnosis to rituximab therapy in the low dose group was 13.7 months and in the standard dose group was 14.4 months. There was no difference in the median patient platelet count before treatment between the groups (28.1 and 26.4 x10^9/L respectively for low dose and standard doss regimes). The median platelet count was not significantly different at 2, 4 and 6 months after rituximab therapy between the low and standard doses (46, 72, 74 x10^9/L and 43, 65, 81 x10^9/L respectively). There was, however, some ongoing increase in platelet count between 2 and 4 months for both dosing schedules showing ongoing delayed response. At 2 months after therapy, complete remission (defined as platelets >100 x 10^9/L) was achieved in 21.1% and 32% patients in the low dose and standard dose regimes respectively. This increased to 37.7% and 43.1% at 6 months. Partial remission at 2 months was achieved in 36 and 27.1% patients for 100mg and 375mg/m2 doses. By 6 months this was 34% and 27% respectively. Bleeding episodes (all bleeds) before and after therapy were reported in 63.7% and 44.7% of patients in the 100mg dose group and 63.9% and 39.3% patients in the 375mg/m2 group. The median number of bleeding events per patient prior to treatment was 2 in both groups (range 0-4). After rituximab the median was 1 in both groups (range 0-2). For those that did bleed, the median time was 4.0 months for 100mg (range 1.6 – 18.7) and 2.8 months for 375mg/m2 (range 1.1 – 12.3). There was no statistically significant difference between these two. For those that required another line of treatment, the median time was 4 months for 100mg and 3 months for the 375mg/m2 dose.

Conclusion
In conclusion, in this large cohort, 100mg rituximab appears to be as effective as 375mg/m2 in improving platelet count and achieving PR. These data show that both doses are equally as effective in reducing bleeds with no difference in the median time to next treatment. This would suggest, that for patients with primary ITP, 100mg rituximab weekly x 4 weeks may be a  more cost-effective option than the standard dosing regimen (375mg/m2 weekly x 4).

Session topic: 33.  Platelets disorders

Keyword(s): Immune thrombocytopenia (ITP), Rituximab

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