The GETUG SEMITEP Trial: De-escalating Chemotherapy in Good-prognosis Seminoma Based on Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Background: In metastatic seminoma, a strategy is needed for selecting patients for less intensive chemotherapy, to limit toxicities.

Objective: To assess whether men with good-prognosis metastatic seminoma could be treated with two cycles of etoposide-cisplatin (EP) followed by only one cycle of carboplatin (CARBO) based on negative interim fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT).

Design, setting, and participants: A nonrandomised, multicentre, phase 2 trial was conducted (NCT01887340).

Intervention: All patients with baseline-positive FDG-PET/CT received EP for two cycles. After completing the first two cycles, the patients underwent a second FDG-PET/CT to assess the response. Patients with positive FDG-PET/CT proceeded directly to two additional EP cycles; those who achieved FDG-PET/CT negativity received one cycle of CARBO.

Outcome measurements and statistical analysis: The proportion of patients with negative interim FDG-PET/CT who received carboplatin was determined.

Results and limitations: Between 2013 and 2017, 102 patients were enrolled. After the first two EP cycles, FDG-PET/CT was available in 98 patients. Overall, 67 patients (68.4%; 95% confidence interval [CI]: 58.2-77.4) had negative FDG-PET/CT and proceeded to a single CARBO cycle. Twenty-seven patients (27.6%; 95% CI: 19.0-37.5) had positive FDG-PET/CT after two EP cycles. The 3-yr progression-free survival rate was 90.0% (95% CI: 74.4-96.5) in the EP group and 90.8% (95% CI: 81.4-95.7) in the CARBO group. The cumulative incidences of peripheral neuropathy and ototoxicity were significantly higher in the EP group.

Conclusions: Omission of two cycles of EP based on negative FDG-PET/CT after two cycles of chemotherapy appears to be feasible. However, the absence of consensus criteria for FDG-PET/CT interpretation and the short follow-up need additional studies. This strategy does not warrant routine integration yet.

Patient summary: Men with good-prognosis metastatic seminoma were treated with fewer cycles of chemotherapy based on interim fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). Omission of two cycles of chemotherapy based on negative FDG-PET/CT after two initial cycles appears to be feasible, thereby limiting the burden of treatment and toxicity.