Comparison of treatments for persistent/chronic immune thrombocytopenia: a systematic review and network meta-analysis

Efficacy and safety of fostamatinib in refractory immune thrombocytopenia: a meta-analysis from randomized controlled trials

BACKGROUND

Immune thrombocytopenia (ITP) is an immune-mediated disease that results in low platelet counts. Despite appropriate treatment, many patients continue to experience refractory disease. Fostamatinib, an oral spleen tyrosine kinase (SYK) inhibitor, has emerged as a promising option for refractory ITP.

OBJECTIVE

This meta-analysis aims to evaluate the efficacy and safety of fostamatinib compared to conventional therapy in adults aged ≥ 18 years with refractory ITP.

MATERIALS AND METHODS

Literature search was conducted in PubMed, Scopus, Embase, and clinicaltrials.gov databases from inception to March 31, 2024. Randomized controlled trials (RCTs) assessing the safety and efficacy of fostamatinib in adults with refractory ITP were included. Data extraction, risk of bias assessment, and statistical analysis were performed following PRISMA guideline.

RESULTS

A total of 495 articles were screened, with three RCTs meeting the inclusion criteria. Fostamatinib therapy demonstrated superior efficacy in achieving stable platelet response by week 24 (ORR 0.80; 95%CI 0.72-0.88), platelet count ≥ 50,000/µL at weeks 12 (ORR 0.80; 95%CI 0.72-0.90) and week 24 (ORR 0.82; 95%CI 0.72-0.90). Additionally, fostamatinib improves platelet counts in subjects with a baseline count of < 15,000/µL. The Number Needed to Treat (NNT) was calculated as 10. Adverse effects include diarrhea (RR 2.32; 95%CI 1.11-4.84), hypertension (RR 2.33; 95%CI 1.00-5.43), and abnormal liver function tests (RR 4.18; 95% CI 1.00-17.48). Interestingly, the occurrences of nausea (RR 1.77; 95% CI 0.33-9.67) and rash (RR 2.28; 95% CI 0.50-10.29) did not achieve statistical significance.

CONCLUSION

This meta-analysis provides robust evidence supporting the efficacy of fostamatinib in improving platelet counts and achieving therapeutic goals in adults with refractory ITP. However, fostamatinib's safety profile warrants consideration due to higher rates of diarrhea, hypertension, and abnormal liver function tests.

Thrombopoietin Receptor Agonists and Other Second-Line Therapies for Immune Thrombocytopenia: A Narrative Review With a Focus on Drug Access in Canada

INTRODUCTION

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts and increased risk of bleeding. After corticosteroids with or without intravenous immune globulin (first-line treatment), second-line treatment options include rituximab, splenectomy, thrombopoietin receptor agonists (TPO-RAs), and fostamatinib. In Canada, the choice of second-line therapy is influenced by access to medications. The goals of this narrative review are to 1) summarize the evidence for the use of TPO-RAs and other second-line therapies in ITP and 2) highlight differences in public funding criteria for TPO-RAs across provinces and territories in Canada.

METHODS

We conducted a literature review of second-line therapies for ITP. We solicited information on public funding programs for TPO-RAs in Canada from health care providers, pharmacists, and provincial ministries of health.

RESULTS

Head-to-head trials involving TPO-RAs, rituximab, splenectomy, and fostamatinib are lacking. There is substantial evidence of effect for TPO-RAs in improving platelet count levels, health-related quality of life, bleeding, and fatigue from placebo-controlled trials and observational studies; however, access to TPO-RAs through provincial funding programs in Canada is variable. Splenectomy failure is a prerequisite for the funding of TPO-RAs in Ontario, Manitoba, and Saskatchewan, but not in Alberta or Quebec. Other provinces either do not have access to public funding or funding is provided on a case-by-case basis.

DISCUSSION

TPO-RAs are effective second-line therapies for the treatment of ITP; however, access is variable across Canada, which results in health disparities and poor uptake of international treatment guidelines.

Efficacy and Safety of Avatrombopag in Patients with Chronic Immune Thrombocytopenia: A Systematic Literature Review and Network Meta-Analysis

INTRODUCTION

A network meta-analysis (NMA) was performed to assess the efficacy and safety of avatrombopag, relative to eltrombopag, romiplostim, and fostamatinib, for patients with chronic immune thrombocytopenia (ITP) not responding adequately to corticosteroids.

METHODS

A systematic search of publication and clinical trial databases was conducted to identify relevant randomized controlled trials (RCTs) and observational studies. Data from eligible studies were extracted and analyzed in a Bayesian framework using relative effect sizes vs placebo. Outcomes included durable platelet response; need for rescue therapy; reduction in use of concomitant ITP medication; incidence of any or World Health Organization (WHO) grade 2-4 bleeding events, and any adverse events. Results were reported as odds ratios or incidence rate ratios (IRR) with 95% credible intervals (CrIs).

RESULTS

The NMA included seven phase 3 RCTs. Compared with placebo, avatrombopag was associated with statistically significant improvements in durable platelet response, reduction in use of concomitant ITP medication, and incidence of any bleeding events. Statistically significant differences vs placebo were also observed for durable platelet response and need for rescue therapy (eltrombopag, romiplostim, and fostamatinib); reduction in use of concomitant ITP medication (eltrombopag and romiplostim); incidence of any bleeding events (fostamatinib); and incidence of WHO grade 2-4 bleeding events (romiplostim and fostamatinib). No statistically significant differences were observed for any adverse events. Avatrombopag was associated with a statistically significant lower incidence of any bleeding events vs eltrombopag (IRR 0.38 [95% CrI 0.19, 0.75]) and romiplostim (IRR 0.38 [95% Crl 0.17, 0.86]); no other between-treatment differences were observed.

CONCLUSION

In this NMA, avatrombopag significantly increased the chance of achieving durable platelet response and reducing the use of concomitant ITP medication vs placebo, and significantly reduced the incidence of any bleeding events compared with placebo, eltrombopag, and romiplostim. The study aims to help guide clinicians managing patients with chronic ITP and insufficient response to previous treatment.

Eltrombopag Effectiveness and Tolerability in Chronic Immune Thrombocytopenia: A Meta-Analysis

Eltrombopag is an orally administered, non-peptide, thrombopoietin receptor agonist which initiates thrombopoietin signaling and stimulates the production of normally functioning platelet. We aimed to do a systematic review and meta-analysis of currently available published data to verify whether eltrombopag treatment in patients with chronic immune-mediated thrombocytopenia can prolong survival. We searched for published, randomized, controlled trials in PubMed, Cochrane and Scopus databases using the following search strategy (“Eltrombopag” OR “Benzoates” OR “Hydrazines”) AND (“Idiopathic Thrombocytopenic Purpura” OR “immune thrombocytopenia” OR “Idiopathic Thrombocytopenic Purpuras” OR “Immune Thrombocytopenia” OR “Autoimmune Thrombocytopenia” OR “Werlhof”). The pooled relative risk (RR) showed that eltrombopag group has significantly higher overall platelet response than placebo group (MD = 3.42, 95% CI [2.51, 4.65], P > .0001); pooled results were homogenous (P = .27, I² = 22%). The pooled relative risk showed that eltrombopag group has lower incidence of any bleeding than placebo group (MD = 0.65, 95% CI [0.48, 0.87], P = .003); pooled results were heterogenous (P = .001, I² = 75%) and the detected heterogeneity was best resolved after excluding Bussel et al (P = .10). Homogeneous results were still favored eltrombopag group (MD = 0.75, 95% CI [0.60, 0.93], P = .008).

Eltrombopag-related renal vein thromboembolism in a patient with immune thrombocytopenia: A case report

BACKGROUND

Eltrombopag is an orally administered thrombopoietin receptor agonist linked to a heightened risk of treatment-related thromboembolism. Both venous and arterial thromboses have been documented in the medical literature.

CASE SUMMARY

In the absence of nephropathy, a 48-year-old patient receiving eltrombopag for immune thrombocytopenia (ITP) developed renal vein thrombosis and pulmonary embolism. The renal vein thrombus spontaneously resolved during subsequent anticoagulant treatment, restoring venous circulation.

CONCLUSION

A rapid upsurge in platelets, rather than their absolute number, may trigger thrombotic events in this setting. For patients at high thrombotic risk, individualized eltrombopag dosing and vigilance in platelet monitoring are perhaps needed during treatment of ITP.

Second-line treatments and outcomes for immune thrombocytopenia: A retrospective study with electronic health records

BACKGROUND

Second-line treatment for immune thrombocytopenia (ITP) is not well reported for patients treated in real-world clinical settings.

OBJECTIVE

The purpose of this study was to compare outcomes of four second-line treatments for ITP.

PATIENTS/METHODS

Included adult patients had at least two medical records containing ITP diagnoses and second-line eltrombopag, romiplostim, rituximab, or splenectomy. Date of treatment initiation or splenectomy was set as index date, between July 1, 2008, and March 31, 2017. Patients had first-line corticosteroid or intravenous immune globulin treatment and continuous database activity from 6 months before to 12 months after index. Patient characteristics, treatment patterns, platelet counts, bleeding-related episodes (BREs), and thrombotic events (TEs) were compared by second-line treatment cohort.

RESULTS

The sample included 3332 patients (mean age, 60.5 years; 52.3% female): eltrombopag (5.8%), romiplostim (9.9%), rituximab (73.3%), and splenectomy (11.0%). Patients having splenectomy were younger, more likely female and commercially insured, and less likely to require a third line of treatment than medical regimen cohorts. Proportions of patients having treatment-free (≥180 days with no second-line index or rescue agent) periods varied significantly (P = .01) by regimen: 33% for eltrombopag, 23% for romiplostim, 26% for rituximab, and 17% for splenectomy. All regimens significantly improved platelet counts, while TE and BRE rates differed significantly (P = .03 and P = .01, respectively) when all treatment groups were compared.

CONCLUSIONS

Over an average 7-year follow-up, all second-line regimens improved platelet counts, but eltrombopag yielded the highest proportion of patients with completely treatment-free periods of at least 180 days.

Disease management of patients with immune thrombocytopenia-results of a representative retrospective survey in Germany

Clinical research has resulted in an improvement of treatment options for patients with immune thrombocytopenia (ITP) over the last years. However, only few data exist on the real-life management of patients with ITP. To expand the knowledge, a multicenter, national survey was undertaken in 26 hematology practices distributed all over Germany. All patients with a diagnosis of ITP were documented using questionnaires, irrespective of the diagnosis date over a period of 2 years. Overall, data of 1023 patients were evaluated with 56% of patients being older than 60 years. Seventy-nine percent of the patients had chronic (> 12 months), 16% persistent (> 3-12 months), and 5% newly diagnosed (0-3 months) ITP. In 61% of cases, the disease lasted 3 or more years before survey documentation started. Main strategies applied as first-line therapy consisted of steroids in 45% and a "watch and wait" approach in 41% of patients. During second- and third-line strategies, treatment with steroids decreased (36% and 28%, respectively), while treatment modalities such as TPO-RAs increased (19% and 26%, respectively). As expected, patients with a low platelet count and thus a higher risk for bleeding and mortality received treatment (esp. steroids) more frequently during first line than those with a higher platelet count. Up to a third of patients were treated with steroids for more than a year. Overall, our study provides a cross-section overview about the current therapeutic treatment landscape in German ITP patients. The results will help to improve therapeutic management of ITP patients.

Rituximab and immune thrombocytopenia in adults: The state of knowledge 20 years later

Rituximab has been used for immune thrombocytopenia (ITP) for almost 20 years and is now considered a valid off-label second-line treatment. About 60% to 70% of patients with ITP show initial response to rituximab, but in half of these patients, the disease will eventually relapse. Therefore, in 30% of patients with persistent or chronic ITP, one course of rituximab at 375 mg/m²/week for 4 weeks or 2 fixed 1000-mg rituximab infusions allows for a sustained response rate at 5 years. Unfortunately, to date, no robust predictor of long-term sustained response has been found to assist the physician in deciding to treat with rituximab on an individual basis, and the choice of rituximab or another second-line treatment must be individualized and shared with the patient. Retreatment with rituximab has been found efficient, with a similar or higher magnitude and duration of response in most patients. Rituximab is usually well tolerated, with mainly mild and easily manageable infusion-related adverse events. Severe infections are uncommon, including in the long-term, and occur in patients with at least another contributing factor in more than two thirds. Several issues remain to be resolved. Indeed, head-to-head comparisons with other and new treatments in ITP and robust predictors of long-term response are urgently needed to better determine the position of rituximab in the therapeutic armamentarium for adult ITP. Additionally, the place of combination therapies, maintenance therapy with rituximab and rituximab in newly-diagnosed ITP deserve additional studies.

Eltrombopag in Immune Thrombocytopenia, Aplastic Anemia, and Myelodysplastic Syndrome: From Megakaryopoiesis to Immunomodulation

Eltrombopag is an orally available thrombopoietin receptor agonist indicated for the treatment of immune thrombocytopenia (ITP). Beyond the effect on megakaryopoiesis, the drug also showed a stimulating effect on the hematopoietic stem cell with consistent clinical efficacy in aplastic anemia (AA) and myelodysplastic syndromes (MDS). Eltrombopag is highly effective in ITP and less so in AA and MDS. This observation underlines the importance of residual normal hematopoiesis, which is maximal in ITP, minimal/absent in AA, and dysregulated in MDS. In ITP, the drug at 50-75 mg daily induced up to 85% responses both in clinical trials and real-life studies, with the possibility of tapering and discontinuation. In AA, eltrombopag at 150 mg daily was effective in about 40% of cases relapsed/refractory to standard immunosuppression or ineligible for bone marrow transplant. In MDS, the drug seems less effective, with responses in about a quarter of patients at various schedules. The efficacy of eltrombopag in ITP, AA, and MDS suggests the existence of common immune-pathological mechanisms in these diseases, including autoimmunity against peripheral blood cells and bone marrow precursors, as well as a possible evolution of one condition into the other. Additional mechanisms of action emerging from the clinical use of eltrombopag include modulation of T-regulatory cells, restoration of Fc-γ receptor balance in phagocytes, and an iron-mobilizing effect. In this review, we analyzed the most recent literature on eltrombopag use and efficacy in patients with ITP, AA, and MDS, exploring the basis for different dosing, combined treatments, and discontinuation in each context.

Treatment efficacy for adult persistent immune thrombocytopenia: a systematic review and network meta-analysis

Persistent immune thrombocytopenia (ITP) patients require second-line treatments, for which information on clinical outcomes are lacking. A systematic review and network meta-analysis (NMA) were conducted. Only randomised controlled trials (RCT) of second-line drugs in adult persistent ITP patients with platelet response, platelet count, any bleeding or serious adverse events (SAE) outcome were eligible. Twelve RCTs (n = 1313) were included in NMA. For platelet response outcome, eltrombopag and romiplostin were the best relative to placebo; the former had a non-significant advantage [risk ratio (RR) = 1·10 (95% confidence interval: 0·46, 2·67)]. Both treatments were superior to rituximab and recombinant human thrombopoietin (rhTPO)+rituximab, with corresponding RRs of 4·56 (1·89, 10·96) and 4·18 (1·21, 14·49) for eltrombopag; 4·13 (1·56, 10·94) and 3·79 (1·02, 14·09) for romiplostim. For platelet count, romiplostim ranked highest, followed by eltrombopag, rhTPO+rituximab, and rituximab. For bleeding, rituximab had lowest risk, followed by eltrombopag and romiplostim. For SAEs, rhTPO+rituximab had highest risk, followed by rituximab, eltrombopag and romiplostim. From clustered ranking, romiplostim had the best balance between short-term efficacy and SAEs, followed by eltrombopag. In conclusion, romiplostim and eltrombopag may yield high efficacy and safety. Rituximab may not be beneficial due to lower efficacy and higher complications compared with the thrombopoietin receptor agonists. RCTs with long-term clinical outcomes are required.