Avatrombopag for chemotherapy-induced thrombocytopenia in patients with non-haematological malignancies: an international, randomised, double-blind, placebo-controlled, phase 3 trial
Al-Samkari H, Kolb-Sielecki J, Safina SZ, Xue X, Jamieson BD
The Lancet. Haematology. 2022;9(3):e179-e189
BACKGROUND Chemotherapy-induced thrombocytopenia is common and causes chemotherapy dose reductions or treatment delays, bleeding, and suboptimal oncological outcomes. We aimed to evaluate avatrombopag, a thrombopoietin receptor agonist that increases platelet counts, in patients with non-haematological cancer and platelet counts lower than 50 ×10(9) cells per L. METHODS In this randomised, double-blind, placebo-controlled, phase 3 study, patients aged 18 years or older at 71 hospitals or cancer treatment centres in China, Hungary, Poland, Russia, Serbia, Ukraine, and the USA and with ovarian, bladder, or lung cancer receiving chemotherapy who had severe thrombocytopenia were randomly assigned (2:1) to oral avatrombopag 60 mg or oral placebo once daily given 5 days before and after chemotherapy, with randomisation stratified by number of chemotherapy drugs used. Patients, investigators, and data collectors were masked to group allocation. Eligibility required two previous lines of chemotherapy or fewer, an ECOG performance status of 2 or less, and no previous history of chemotherapy-induced thrombocytopenia. The composite primary endpoint was the proportion of responders not requiring platelet transfusion or either a 15% or more chemotherapy dose reduction or a 4-day or more chemotherapy delay due to thrombocytopenia following study treatment until the start of the subsequent cycle. Analyses were done on the intention-to-treat and per protocol populations. Safety was analysed in all patients who received at least one dose of avatrombopag. The trial is registered with ClinicalTrials.gov, NCT03471078, and has been completed. FINDINGS Between Oct 12, 2018, and June 28, 2020, 122 patients were enrolled and randomly assigned to receive avatrombopag (n=82) or placebo (n=40). Median follow-up was 31 days (IQR 22-61). Similar proportions of patients reached the primary endpoint in the avatrombopag and placebo groups (intention-to-treat: 57 [70%, 95% CI 58-79] of 82 vs 29 [73%, 95% CI 56-85] of 40; difference -3·0% (95% CI -21·6 to 15·6); p=0·72; per protocol: 51 [85%, 95% CI 73-93] of 60 vs 27 [84%, 95% CI 67-95] of 32; 0·6% (95% CI -20·8 to 22·1); p=0·96). 15 (18%) of 82 patients had serious adverse events in the avatrombopag group and eight (20%) of 40 in the placebo group, of which thrombocytopenia was most common (4 [5%] of 82 and 4 [10%] of 40 patients). Common grade 3-4 treatment-emergent adverse events were neutropenia (22 [27%] of 82 and 16 [40%] of 40 patients), leukopenia (19 [23%] of 82 and 5 [13%] of 40), anaemia (16 [20%] of 82 and 9 [23%] of 40), and thrombocytopenia (16 [20%] of 82 and 14 [35%] of 40). Most adverse events were considered unrelated to study drug. No treatment-related deaths were reported. INTERPRETATION In this population of patients with non-haematological malignancies who are relatively chemotherapy naive, chemotherapy-induced thrombocytopenia treatment outcomes were similar between the avatrombopag and placebo groups. Given its safety and ability to augment platelet counts in patients with chemotherapy-induced thrombocytopenia, evaluation of avatrombopag in populations with more persistent chemotherapy-induced thrombocytopenia is warranted. FUNDING Dova Pharmaceuticals, a Sobi company.
The efficacy and safety of thrombopoietin receptor agonists in patients with chronic liver disease undergoing elective procedures: a systematic review and meta-analysis
Lindquist I, Olson SR, Li A, Al-Samkari H, Jou JH, McCarty OJT, Shatzel JJ
Thrombopoietin receptor agonists (TPO-RAs) can mitigate preprocedural thrombocytopenia in patients with chronic liver disease (CLD) however their effects on procedural outcomes is unclear. In this meta-analysis, we aimed to better define the efficacy, thrombotic risk and bleeding mitigation associated with the use of preoperative TPO-RAs in patients with CLD. We performed a systematic review and meta-analysis of randomized placebo-controlled clinical trials to assess the use of preprocedural TPO-RAs in patients with CLD, searching MEDLINE, EMBASE and the Cochrane library database. Six publications comprising eight randomized trials (1229 patients; 717 received TPO-RAs, 512 received placebo) and three unique TPO-RAs were retrieved. The majority of the included procedures were endoscopic. TPO-RAs were significantly more likely to result in a preoperative platelet count greater than 50 x 10(9)/L (72.1% vs 15.6%, RR 4.8, 95% CI 3.6-6.4 p < .00001. NNT 1.8) and reduced the incidence of platelet transfusions (22.5% vs 67.8%, RR 0.33, 95% CI 0.3-0.4 p < .00001. NNT 2.2). Total periprocedural bleeding was decreased in patients who received TPO-RAs (11.6% vs 15.6%, RR 0.64, 95% CI 0.5-0.9 p = .01. NNT 24.7) and there was no increase in the rate of thrombosis (2.2% vs 1.8% RR 1.25, 95% CI 0.6-2.9 p = .60. NNH 211.1). In patients with CLD the use of preprocedural TPO-RAs resulted in significant increased platelet counts, and decreased the incidence of platelet transfusions as compared to placebo. TPO use likewise decreased the incidence of total periprocedural bleeding without increasing the rate of thrombosis.
Efficacy and safety evaluation of avatrombopag in immune thrombocytopenia: analyses of a phase III study and long-term extension
Al-Samkari H, Nagalla S
Avatrombopag is an oral thrombopoietin receptor agonist approved for chronic immune thrombocytopenia (ITP). This is a post hoc analysis of the pivotal phase III study (NCT01438840) evaluating additional endpoints not previously described. Thirty-two ITP patients were randomized to avatrombopag and 17 were randomized to placebo during a 26-week core study period (with 21 study visits), followed by an open-label extension period, in which all patients received avatrombopag for varying lengths of time. In this analysis, we evaluated previously unreported response rates at the study visit level, durability of response, and reduction in corticosteroid use with avatrombopag treatment. In the core study, more avatrombopag-treated patients achieved either response (Plt ≥50 000/µL) or complete response (Plt ≥100 000/µL) than placebo-treated patients by day 8 (65.6% vs. 0%; P < .0001 for response; 37.5% vs. 0%; P < .0001 for complete response), day 28 (84.4% vs. 0%; P < .0001 for response; 71.9% vs. 0%; P < .0001 for complete response), and month 6 (87.5% vs. 5.9%; P < .0001 for response; 81.3% vs. 5.9%; P < .0001 for complete response). Durable responders from the core study achieved response and complete response at 96.1% and 60.1% of extension phase visits, respectively. Durable clinically relevant response (Plt ≥30 000/µL for 6 of the final 8 weeks of the core study) occurred in 64.0% of avatrombopag-treated patients versus 0% of placebo-treated patients. More than half (57.1%) of patients on chronic corticosteroids reduced or discontinued corticosteroids. In conclusion, avatrombopag enabled most patients with ITP to achieve clinically meaningful and durable platelet count improvements.
Thrombopoietin receptor agonists and rituximab for treatment of pediatric immune thrombocytopenia: A systematic review and meta-analysis of prospective clinical trials
Ayad N, Grace RF, Al-Samkari H
Pediatric blood & cancer. 2021;:e29447
BACKGROUND Children with immune thrombocytopenia (ITP) may require second-line ITP therapies. The high remission rate in pediatric patients, need for extended-duration use of thrombopoietin receptor agonists (TPO-RAs), drug adherence, potential side effects, monitoring, and cost effectiveness are factors that should be considered in decision-making about second-line therapies. Rituximab (RTX) has been used off-label for years to treat ITP but there are limited studies about its efficacy and safety in children. To date, no studies have directly compared TPO-RAs with RTX for the treatment of childhood ITP. METHODS This systematic review analyzed the overall platelet response, durability of treatment effect, and safety for RTX use in comparison to TPO-RAs in pediatric ITP. MEDLINE/PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched through December 2020 and meta-analysis was conducted using proportions of success/failure for each intervention in the selected studies. RESULTS The proportion of participants achieving the primary endpoint of a platelet response above 50,000 was similar for TPO-RAs (proportion = 0.71, 95% CI: 0.63-0.78) and RTX (proportion = 0.68, 95% CI: 0.53-0.82). However, considerable variation was found between the two groups with regards to the sustainability of the response and other secondary outcomes such as need for rescue and adverse events. RTX was associated with higher rates of rescue therapy. CONCLUSIONS In this analysis of prospective pediatric ITP studies, RTX and TPO-RAs had similar rates of overall platelet response but differed in other important measures. Prospective comparative studies are needed to better characterize second-line treatments for pediatric ITP.
Children with immune thrombocytopenia lasting 6 months or longer, and enrolled in randomised controlled trials (RCTs) and non-randomised studies, identified by systematic review (n= 498, 6 RCTs, 5 non-randomised studies).
Thrombopoietin receptor agonists (TPO-Ras).
The proportion of participants achieving the primary endpoint of a platelet response above 50,000 was similar for TPO-RAs (proportion= 0.71, 95% CI: 0.63-0.78) and RTX (proportion= 0.68, 95% CI: 0.53-0.82). However, considerable variation was found between the two groups with regards to the sustainability of the response and other secondary outcomes such as need for rescue and adverse events. RTX was associated with higher rates of rescue therapy.