Pazopanib in advanced germ cell tumors after chemotherapy failure: Results of the open-label, single-arm, phase 2 Pazotest trial

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Abstract

Background: Therapeutic options for patients with chemoresistant germ cell tumors (GCTs) are limited. Pazopanib is a selective tyrosine kinase inhibitor with distinct antiangiogenic activity. We aimed to evaluate pazopanib activity in patients with refractory GCT. Patients and methods: In the open-label, single-arm, phase 2 Pazotest study (NCT01743482), patient eligibility included failure of≥2 platinum-based regimens, and allowed prior high-dose chemotherapy administration. Patients were given pazopanib 800 mg/day until disease progression (PD) or onset of unacceptable toxicity. Measurements of serum tumor markers (STM), computed tomography and FDG-PET were carried out at baseline, after 4 weeks of pazopanib treatment, and every 8 weeks thereafter. PD was defined as increasing levels of STM, increasing size of non-teratomatous masses, or appearance of new lesions. The study primary endpoint was progression-free survival (PFS, H0: 3-month PFS≤10%, H1:≥25%, α=5%, β=20%). Results: Forty-three patients were enrolled from May 2013 to July 2016. The number of prior chemotherapy regimens was: 2 (11.6%), 3 (51.2%), >3 (37.2%). Grade 3 adverse events were observed in six patients (13.9%). Overall, 70.3% of patients had reduced levels of STM after 4 weeks. There were 2 partial responses (4.7%), 19 cases of stable disease, and 16 cases of PD (6 not evaluable by RECIST). The median follow-up duration was 29.6 months. The 3-month PFS probability was 12.8% [95% confidence interval (CI): 5.7%-28.9%]. The 24-month OS probability was 14.2% (95% CI: 6.0%-33.7%). In patients with a>50% decline in STM, the 24-month OS probability was 24.1% (95% CI: 8.3%-69.6%). The small sample size was the major limitation. Conclusions: Despite pazopanib showed potent but short-lived activity in refractory GCT, long-term survival was obtained in a proportion of treated patients. According to the kinetics of pazopanib activity, this drug may be investigated in less pre-treated patients as an optimal bridging therapy preceding and/or combined with salvage chemotherapy.

Original languageEnglish
Article numbermdx124
Pages (from-to)1346-1351
Number of pages6
JournalAnnals of Oncology
Volume28
Issue number6
DOIs
Publication statusPublished - Jun 1 2017

Keywords

  • Germ cell tumors
  • Pazopanib
  • Salvage therapy
  • Testicular cancer

ASJC Scopus subject areas

  • Hematology
  • Oncology

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