Human INF-α therapy in desmoid tumors: A retrospective study.

Abstract

e20505 Background: Aggressive fibromatosis (desmoid tumors) are locally invasive, nonmetastatic and have a high local recurrence rate after primary resection. For patients (pts) where surgery is not an option, effective medical treatments are needed. Positive responses with INF-α therapy are reported and supported by in vitro results, was our reason to treat pts with human leukocyte interferon-alpha (Multiferon [M]). Methods: M is an INF-α product obtained from the leukocyte fraction of human blood. The product is highly purified with multiple subtypes including α1, α2, α8, α10, α14 and α21. Pts from 2 sites were included in this retrospective study. Pts had progressive symptoms, were inoperable without considerable morbidity and for whom RT, chemotherapy or hormone therapy also were unwanted. Results: 11 patients were included and 5 are still on treatment. Average age was 38 years and average follow-up time is currently 344 days. Pts N1 to N8 were INF-α naïve, whereas S1 to S3 were changed from peginterferon treatment to M treatment due to suspected anti-interferon antibodies with progression of disease (S1 and S3) or livertoxicity (S2). Of the 8 naïve pts, 2 had PR, 5 had SD, 1 no follow-up MRI scan yet. Six of 8 pts experienced clinical improvement such as regression of pain, increased mobility or other relevant parameters. For N2 and N5 the MRI sequences revealed lower intensity signal, reflecting a greater amount of less active fibrotic tissue. N5 experienced 13% shrinkage in second largest tumor diameter. N1 reached max response of 60% decrease in largest diameter, after 1½ years treatment. Treatment was stopped after 31 mth and tumor still stable 5 mth later. For pts S1 to S3 all had SD, 2 had clinical improvement, 1 had clinical worsening. Conclusions: Treatment response emerges slowly. M may be a new promising treatment option for desmoid tumors. The presentation will present latest follow-up data. Pt Sex Age Tumor location Response Clinical improvement yes/no % change from baseline Follow-up time days N1 M 44 Abd PR Y -60 929 N2 F 28 Ex SD Y +6 661 N3 F 24 Ex SD N +11 191 N4 M 68 Head and Neck PR Y -38 620 N5 F 29 Gluteal SD Y 0 238 N6 M 29 Abd SD Y -7 137 N7 F 35 Tru SD N -6 57 N8 M 63 Ex - Y - - S1 F 29 Ex SD N +4 84 S2 F 17 Ex SD Y -3 558 S3 F 49 Tru SD Y -2 176 Abbreviations: Abd, abdominal; Tru, superficial trunk; Ex, extremity.