Ezabenlimab (BI 754091) plus modified docetaxel, cisplatin, and 5-fluorouracil (mDCF) followed by chemoradiotherapy (CRT) in patients (pts) with stage III squamous cell anal carcinoma (SCCA): Early efficacy endpoint results from the phase II INTERACT-ION study.

Abstract

2 Background: CRT is the standard of care for locally advanced SCCA. However, up to 50% of pts experience recurrence/definitive colostomy; there is an unmet need for novel treatment (Tx) options to improve pt outcomes. mDCF is a standard first-line Tx for advanced SCCA, and anti-programmed death protein-1 (PD-1) immunotherapy has been shown to be effective in a subset of chemorefractory SCCA. Preclinical and clinical data support the feasibility and the potential of combining mDCF with anti-PD-1 immunotherapy. Methods: INTERACT-ION (NCT04719988) is an open-label, single-arm study in pts with Tx-naïve Stage III (T4N0 or TxN+) SCCA to evaluate ezabenlimab (anti-PD-1 antibody) plus mDCF as induction therapy, followed by CRT and then maintenance with ezabenlimab. Pts received induction ezabenlimab (240 mg intravenously, every 3 weeks, 3 cycles) plus mDCF (D [40 mg/m2], C [40 mg/m2] on Day 1; F [1200 mg/m2/day for 2 days] every 2 weeks, 4 cycles). If there was no disease progression after 2 months, pts received an additional cycle of ezabenlimab plus 2 cycles of mDCF. Planned early efficacy endpoint analyses were performed after 2 months of Tx. Pts with radiological objective response (OR; RECIST v1.1), pathological (p) complete response (CR)/near CR (<10% viable tumor cells) by repeat biopsy, and molecular CR (undetectable human papillomavirus [HPV] circulating tumor DNA) by liquid biopsy, received involved nodetumor bed CRT with intensity-modulated radiation therapy (IMRT) followed by 7 cycles of ezabenlimab. All other pts received standard IMRT based-CRT. The primary endpoint is the clinical CR rate 10 months after Cycle 1 of ezabenlimab plus mDCF. Results: At analysis cut-off date,43 pts had been enrolled; 37 pts had preliminary early efficacy endpoint evaluation. All but 1 pt (97.3%) received the planned 4 cycles of ezabenlimab plus mDCF prior to evaluation; 1 pt presented with treatment-related capillary leak syndrome after Cycle 1 and died of a lung infection 3 months later. Radiological assessment was performed in 33 pts; 32 (97.0%) had radiological OR including 14 (42.4%) with CR. One HPV- pt had disease progression. Pathological response data were available for 21 pts; 16 (76.2%) had pCR/near pCR. For molecular response, 3 pts were HPV- (excluded). Among 23 HPV+ evaluable pts, 21 (91.3%) had a molecular CR. Two pts had a significant decrease at 2 months (decrease: 14/1 and 54/1); then molecular CR after radiotherapy. No safety signals were identified by an independent safety review committee. Conclusions: Preliminary results from this ongoing Phase II study show promising antitumor activity and manageable safety of ezabenlimab plus mDCF in pts with Tx-naïve, locally advanced SCCA. Further evaluation of this new treatment regimen is warranted. Clinical trial information: NCT04719988 .