Temozolomide (TMZ) is part of the standard treatment for patients with glioblastoma, but the drug carries a dosedependent risk of grade 3 or 4 thrombocytopenia. This frequently means patients are unable to complete the full cycle of glioblastoma treatment.
In results from a phase II, multicenter, single-arm trial presented at the 2018 American Society of Clinical Oncology Annual Meeting, investigators reported that treatment with the thrombopoietin receptor agonist romiplostim allowed more patients to complete maintenance therapy with TMZ, without the need for treatment interruptions or discontinuations.
The investigators, led by Emilie Le Rhun, MD, of the University of Lille in France, enrolled patients with histologically confirmed, newly diagnosed glioblastoma who developed thrombocytopenia after receiving TMZ chemotherapy with or without radiation therapy.
Romiplostim was initiated at least one week after completion of radiation therapy and TMZ, at a starting dose of 750 μg administered via subcutaneous injection.
Dosing of romiplostim was adjusted throughout the trial, according to weekly platelet count assessments. With the following guidelines for therapy adjustments, if the weekly platelet count was:
- <100×109/L for 2 consecutive weeks, romiplostim should be increased by one dose level (maximum: 1000 μg/week)
- 100 to 200×109/L, the same dose should be continued
- 200 to 400×109/L for two consecutive weeks, romiplostim should be reduced by one dose level (500 μg/week)
- >400×109/L, treatment should be withheld and reinitiated if <200×109/L with one level lower than the last dose
Twenty patients (median age = 61 years; range = 33-73 years) were enrolled between July 2014 and December 2016. The median platelet count at enrollment was 65×109/L (range = 25×109/L to 146×109/L) at initiation of TMZ and/or radiation therapy.
After receiving romiplostim, 12 patients continued on to receive six cycles of maintenance therapy with TMZ, representing a success rate of 60 percent (the study’s primary endpoint). Twelve patients died during treatment, which translated to a median overall survival of 15.18 months (range = 3-33 months).
Nineteen patients experienced at least one adverse event (AE), and 11 patients reported at least one severe treatmentrelated AE. Based on these data, the investigators concluded that romiplostim was well tolerated in this setting, adding that the trial was terminated early due to success.
Limitations of the analysis include the study’s single-arm design, which reduced the ability to determine the therapy’s superiority or inferiority over other similar drugs used in this patient population. In addition, the small number of patients enrolled limits the findings’ generalizability and clinical relevance.
The authors of this study report financial relationships with Abbvie, Daiichi Sankyo, Amgen, Mundipharma, Bristol-Myers Squibb, Immatics, IPSEN, SERVIER, Roche, Lilly, Merck Serono, MSD, Novocure, Teva, Pfizer, Actelion, Tragara, OGD2 Pharma, and Merck Sharp & Dohme.
Rhun EL, Devos P, Houillier C, et al. Secondary prophylaxis with romiplostim for temozolomide-induced thrombocytopenia in newly diagnosed glioblastoma. Abstract #2042. Presented at the 2018 Annual Meeting of the American Society of Clinical Oncology, June 2, 2018; Chicago, IL.