1523MO - Initial active surveillance strategy for patients with peripheral sporadic desmoids: A multicentre phase II observational trial

Background

Desmoid tumors (DT) are characterized by an unpredictable course. Most of the existing literature consists of retrospective studies. In a previous double-blind phase 3 trial comparing sorafenib and placebo, the 2-year Progression Free Survival (PFS) rate of the placebo group was 36% (Gounder NEJM 2018). However, assigned patients had already progressive or recurrent DT. The primary endpoint of this observational phase 2 study was to evaluate PFS and treatments at progression of newly diagnosed sporadic DT. Secondary endpoints included pain evaluation and record of continued surveillance or treatments after progression.

Methods

NCT01801176 was conducted in 9 hospitals from the French Sarcoma Group. Adults with histologically documented, primary DT, located on superficial trunk or extremities, not previously treated were proposed to Active Surveillance (AS) after signed informed consent. MRI were performed at 1, 3 and then each 6 months, tumor size was centrally assessed (RECIST). Pain evaluation was scored by CTAV4.

Results

Between 2012 and 2015, 100 patients (pts) were enrolled. Female/male ratio was 8; median age was 35.5 years (IQR 26-45). Locations were: extremities n=28, abdominal wall n = 49, thoracic wall n = 23. Median follow up was 46.6 months (IQR 36.8–61.1). PFS at 2 and 3 years were 59.1% (49.2-68.4) and 53.4% (43.5-63.1). The best response was: CR: 8/90 pts (8.9%); PR: 20/90 pts (22.2%); SD: 60/90 pts (66.7%); Progression (P) = 2/90 pts (2.2 %), missing n =10 pts. Median Time to spontaneous response was 38.6 months (29.8-NA). Median TTP was 6.74 months (5.65-10.65). Median ratio of Tumor size/Tumor baseline size decreased after 9 months. Median visual pain score at 3-months was 0 (0-0.75). Age, location, tumor size and betacatenin mutations did not impact PFS in the Cox model. At progression (n = 48 patients), 25 continued AS, 4 received cryoablation, 4 received radiotherapy, 10 hormonal treatment, 4 chemotherapy, and 1 was operated.

Conclusions

Active surveillance of newly diagnosed DT is an effective strategy to better select indications for treatment and spare patients from aggressive treatments when unnecessary. The onset of the decrease of the ratio of median tumor size/baseline size may take 9 months.

Clinical trial identification

NCT01801176.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

National Grant from Institut National du Cancer, INCa, France.

Disclosure

All authors have declared no conflicts of interest.