In analysis, the therapy plus standard immunosuppressive therapy resulted in a complete response rate 27% greater than that historically observed in patients treated with lone IST, over 6 months.
The US Food and Drug Administration (FDA) has expanded the label for eltrombopag (Promacta) to now include indication for adults and pediatric patients 2 years and older with severe aplastic anemia (SAA) in combination with standard immunosuppressive therapy (IST).
The oral thrombopoietin receptor agonist (TPO-RA) has been previously approved by the FDA for SAA for patients with an insufficient response to IST, for adults and children with chronic immune thrombocytopenia (ITP) who are refractory to other therapies, and for patients with chronic hepatitis C virus infection who also suffer from thrombocytopenia.
This newest indication was based on analysis from Novartis—and sponsored by the National Heart, Lung and Blood Institute Division of Intramural Research Program—which showed 44% (95% CI: 33-55) of IST-naïve SAA patients administered the therapy and concurrent standard IST achieved complete response at 6 months. This rate, investigators noted, was 27% greater than the complete response rate historically observed in patients treated with lone IST.
Overall response rate was reported at 79% (95% CI: 69-87) of patients at 6 months.
As a rare, life-threatening, acquired blood disorder in which a patient's bone marrow fails to produce enough red blood cells, white blood cells, and platelets, SAA was once regarded a certainly-fatal disease. Even in recent years, clinicians have struggled to get uniform response from IST therapy, as noted by Liz Barrett, chief executive officer of Novartis Oncology.
“Today's US approval for Promacta is an important step forward for people living with this challenging disease and shows how Novartis continues to reimagine care in areas where few treatment options exist,” Barrett said.
Supporting trial data also show that IST-naïve patients with SAA had a median duration of 24.3 months sustained response when receiving 6 months of eltrombopag plus horse anti-thymocyte globulin (h-ATG) and cyclosporine (CsA), followed by maintenance CsA4. The most common adverse events reported by patients (incidence > 5%) included abnormal liver function tests, rash, and skin discoloration.
Along with the approval, eltrombopag was granted Breakthrough Therapy designation by the FDA, for its clinical application as a counter measure for hematopoietic sub-syndrome of acute radiation syndrome (H-ARS).
As Novartis awaits decision on a submitted application of eltrombopag as a first-line SAA therapy to the European Medicines Agency, the therapy’s role as critical therapy for SAA in the US has been bolstered.
“Patients with SAA sometimes do not respond to the current treatment standard of IST," said Phillip Scheinberg, MD, head of the Division of Hematology, Hospital A Beneficência Portuguesa de São Paulo in Brazil. "With this approval, physicians now have an option to add Promacta to the standard IST in a regimen that has demonstrated significant overall and complete response rates upfront in SAA and reduce the numbers of those who are unresponsive to initial therapy."