Immune Thrombocytopenic Purpura (ITP) Treatments

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In clinical trials, hemorrhage was the most common serious adverse reaction and most hemorrhagic reactions followed discontinuation of eltrombopag. Other serious adverse reactions included thrombotic/thromboembolic complications

Table 8 presents the most common adverse drug reactions (experienced by greater than or equal to 3% of patients receiving eltrombopag) from the three placebo-controlled trials, with a higher incidence in eltrombopag versus placebo.

In the three controlled clinical persistent or chronic ITP trials, alopecia, musculoskeletal pain, blood alkaline phosphatase increased, and dry mouth were the adverse reactions reported in 2% of patients treated with eltrombopag and in no patients who received placebo.

Among 302 patients with persistent or chronic ITP who received eltrombopag in the single-arm extension trial, the adverse reactions occurred in a pattern similar to that seen in the placebo-controlled trials. Table 9 presents the most common treatment-related adverse reactions (experienced by greater than or equal to 3% of patients receiving eltrombopag) from the extension trial.

In the three controlled persistent or chronic ITP trials, serum liver test abnormalities (predominantly Grade 2 or less in severity) were reported in 11% and 7% of patients for eltrombopag and placebo, respectively. Four patients (1%) treated with eltrombopag and three patients in the placebo group (2%) discontinued treatment due to hepatobiliary laboratory abnormalities. Seventeen of the patients treated with eltrombopag in the controlled trials with hepatobiliary laboratory abnormalities were re-exposed to eltrombopag in the extension trial. Eight of these patients again experienced liver test abnormalities (less than or equal to Grade 3) resulting in discontinuation of eltrombopag in one patient. In the extension persistent or chronic ITP trial, six additional patients had eltrombopag discontinued due to liver test abnormalities (less than or equal to Grade 3).

In the three controlled persistent or chronic ITP trials, cataracts developed or worsened in 7% of patients treated with eltrombopag and 7% of patients in the placebo group. All patients had documented, preexisting risk factors for cataractogenesis, including corticosteroid use. In the extension trial, cataracts developed or worsened in 11% of patients who underwent ocular examination prior to therapy with eltrombopag. Seventy-two percent of patients had preexisting risk factors, including corticosteroid use.

The safety of eltrombopag was also assessed in all patients treated in 7 adult persistent or chronic ITP clinical trials (N = 763 eltrombopag-treated patients and 179 placebo-treated patients). Thromboembolic events were reported in 6% of eltrombopag-treated patients versus 0% of placebo-treated patients and thrombotic microangiopathy with acute renal failure was reported in < 1% of eltrombopag-treated patients versus 0% of placebo-treated patients.

In a placebo-controlled trial of eltrombopag in patients with chronic liver disease and thrombocytopenia not related to ITP, six patients treated with eltrombopag and one patient in the placebo group developed portal vein thromboses

The data described below reflect median exposure to eltrombopag of 91 days for 107 pediatric patients (aged 1 to 17 years) with persistent or chronic ITP, of whom 53% were female, across the randomized phase of two placebo-controlled trials.

Table 10 presents the most common adverse drug reactions (experienced by greater than or equal to 3% of pediatric patients 1 year and older receiving eltrombopag) across the two placebo-controlled trials, with a higher incidence for eltrombopag versus placebo.

In the two controlled clinical persistent or chronic ITP trials, cataracts developed or worsened in 2 (1%) patients treated with eltrombopag. Both patients had received chronic oral corticosteroids, a risk factor for cataractogenesis.

In the two placebo-controlled trials, 955 patients with chronic hepatitis C-associated thrombocytopenia received eltrombopag. Table 11 presents the most common adverse drug reactions (experienced by greater than or equal to 10% of patients receiving eltrombopag compared with placebo).

Rash was reported in 9% and 7% of patients receiving eltrombopag and placebo, respectively.

In the two controlled clinical trials in patients with chronic hepatitis C, hyperbilirubinemia was reported in 8% of patients receiving eltrombopag compared with 3% for placebo. Total bilirubin greater than or equal to 1.5 x ULN was reported in 76% and 50% of patients receiving eltrombopag and placebo, respectively. ALT or AST greater than or equal to 3 x ULN was reported in 34% and 38% of patients for eltrombopag and placebo, respectively.

In the two controlled clinical trials in patients with chronic hepatitis C, cataracts developed or worsened in 8% of patients treated with eltrombopag and 5% of patients treated with placebo.

The safety of eltrombopag was also assessed in all patients treated with eltrombopag in the two controlled trials, including patients who initially received eltrombopag in the pre-antiviral treatment phase of the trial and were later randomized to the placebo arm (N = 1,520 eltrombopag-treated patients). Hepatic failure was reported in 0.8% of eltrombopag-treated patients and 0.4% of placebo-treated patients.

The safety of eltrombopag was established based upon a single-arm trial of 153 patients with severe aplastic anemia who had not received prior definitive immunosuppressive therapy. In this trial, eltrombopag was administered in combination with horse antithymocyte globulin (h-ATG) and cyclosporine

In this cohort, eltrombopag was administered at up to 150 mg once daily on Day 1 to Month 6 (D1-M6) in combination with h-ATG on Days 1 to 4 and cyclosporine for 6 months, followed by low dose of cyclosporine (maintenance dose) for an additional 18 months for patients who achieved a hematologic response at 6 months. The median duration of exposure to eltrombopag in this cohort was 183 days with 70% of patients exposed for > 24 weeks.

Table 12 presents the most common adverse reactions (experienced by greater than or equal to 5% of patients) associated with eltrombopag in the D1-M6 cohort.

In the eltrombopag D1-M6 cohort, ALT increased (29%), AST increased (17%) and blood bilirubin increased (17%) were reported more frequently than in patients with refractory severe aplastic anemia (see Table 13).

New or worsening liver function laboratory abnormalities (CTCAE Grade 3 and Grade 4) in the eltrombopag D1-M6 cohort were 15% and 2% for AST, 26% and 4% for ALT and 12% and 1% for bilirubin, respectively.

In this single-arm open-label clinical trial, ALT or AST > 3 x ULN with total bilirubin > 1.5 x ULN and ALT or AST > 3 x ULN with total bilirubin > 2 x ULN were reported in 44% and 32% of patients, respectively, in the eltrombopag D1-M6 cohort.

A total of 34 pediatric patients (2 patients 2 to 5 years of age, 12 patients 6 to 11 years of age and 20 patients 12 to 16 years of age) were enrolled in this single-arm trial of which 26 pediatric patients were enrolled in the eltrombopag D1-M6 cohort. In this cohort, the most frequent serious adverse reactions (experienced by ≥ 10% of patients) were upper respiratory tract infection (12% in patients age 2 to 16 years compared to 5% in patients 17 years of age and older, respectively) and rash (12% compared to 2%). The most common adverse reactions (experienced by ≥ 10% of patients) associated with eltrombopag were ALT increased (23% in patients age 2 to 16 years compared to 32% in patients 17 years of age and older, respectively), blood bilirubin increased (12% compared to 20%), AST increased (12% compared to 20%) and rash (12% compared to 6%).

In this trial, patients had bone marrow aspirates evaluated for cytogenetic abnormalities. Seven patients in the eltrombopag D1-M6 cohort had a new cytogenetic abnormality reported of which 4 had the loss of chromosome 7; these 4 occurred within 6.1 months. Across all cohorts, clonal cytogenetic evolution occurred in 15 out of 153 (10%) patients. Of the 15 patients who experienced a cytogenetic abnormality: 7 patients had the loss of chromosome 7, 6 of which occurred within 6.1 months; 4 patients had chromosomal aberrations which were of unclear significance; 3 patients had a deletion of chromosome 13; and 1 patient had a follow-up bone marrow assessment at 5 years with features of dysplasia with hypercellularity concerning for potential development of MDS. It is unclear whether these findings occurred due to the underlying disease, the immunosuppressive therapy, and/or treatment with eltrombopag.

In the single-arm, open-label trial, 43 patients with refractory severe aplastic anemia received eltrombopag. Eleven patients (26%) were treated for greater than 6 months and 7 patients (16%) were treated for greater than 1 year. The most common adverse reactions (greater than or equal to 20%) were nausea, fatigue, cough, diarrhea, and headache.

Rash and hyperbilirubinemia were reported in 7% of patients; cataract was reported in 2% of patients.

In this trial, concurrent ALT or AST greater than 3 x ULN with total bilirubin greater than 1.5 x ULN were reported in 5% of patients. Total bilirubin greater than 1.5 x ULN occurred in 14% of patients.

In this trial, patients had bone marrow aspirates evaluated for cytogenetic abnormalities. Eight patients had a new cytogenetic abnormality reported on therapy, including 5 patients who had complex changes in chromosome 7.

The following adverse reactions have been identified during post approval use of eltrombopag. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate the frequency or establish a causal relationship to drug exposure.