(Fibromatosis) Could Pazopanib Become a New Treatment Option?

• September 27, 2019
• Reading time: 2 minutes

On July 19, 2019, Maud Toulmonde published in The Lancet Oncology the Phase 2 trial results evaluating the efficacy and safety of the multikinase inhibitor pazopanib in patients with refractory fibromatosis.

Trial Design

This was an open-label, Phase 2 trial randomizing refractory fibromatosis patients aged ≥18 years (N=72) in a 2:1 ratio to:

• Pazopanib group: Pazopanib 800 mg once daily (N=48)
• Vinblastine + Methotrexate group: Vinblastine 5 mg/m² + methotrexate 30 mg/m² (N=24)

Primary endpoint: 6-month progression-free survival (PFS) rate. Secondary endpoint: Safety.

Background: Currently, the only confirmed effective chemotherapy for fibromatosis patients is vinblastine plus methotrexate. No other effective treatments exist. High VEGF response is a characteristic of refractory fibromatosis, and pazopanib — targeting VEGFR1, 2, and 3 — may be effective. Based on this rationale, this trial was initiated.

Efficacy Results

Among 43 evaluable patients at a median follow-up of 23.4 months:

• 6-month PFS rate (primary endpoint):
  • Pazopanib group: 83.7%
  • Vinblastine + Methotrexate group: 45.0%

Safety Profile

Most common Grade 3–4 adverse events:

• Pazopanib group: Hypertension 21% (N=10), diarrhea 15% (N=7)
• Vinblastine + Methotrexate group: Neutropenia 45% (N=10), ALT elevation 18% (N=4)

Serious adverse event rates:

• Pazopanib group: 23% (N=11)
• Vinblastine + Methotrexate group: 27% (N=6)

Conclusions

Based on Phase 2 results, Maud Toulmonde concluded that pazopanib demonstrated favorable antitumor activity in refractory fibromatosis patients, and is a promising alternative treatment option beyond vinblastine plus methotrexate therapy.

Source: Pazopanib for treatment of advanced extraskeletal myxoid chondrosarcoma: a multicentre, single-arm, phase 2 trial. Lancet Oncol. 2019 Jul 19. doi: 10.1016/S1470-2045(19)30276-1.

Tags: #Fibromatosis

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