The Double Antibody Drug Conjugate (DAD) phase I trial: sacituzumab govitecan plus enfortumab vedotin for metastatic urothelial carcinoma

BACKGROUND

The antibody-drug conjugates sacituzumab govitecan (SG) and enfortumab vedotin (EV) are standard monotherapies for metastatic urothelial carcinoma (mUC). Given the different targets and payloads, we evaluated the safety and efficacy of SG + EV in a phase I trial in mUC (NCT04724018).

PATIENTS AND METHODS

Patients with mUC and Eastern Cooperative Oncology Group performance status ≤1 who had progressed on platinum and/or immunotherapy were enrolled. SG + EV were administered on days 1 + 8 of a 21-day cycle until progression or unacceptable toxicity. Primary endpoint was the incidence of dose-limiting toxicities during cycle 1. The number of patients treated at each of four pre-specified dose levels (DLs) and the maximum tolerated doses in combination (MTD) were determined using a Bayesian Optimal Interval design. Objective response, progression-free survival, and overall survival were secondary endpoints.

RESULTS

Between May 2021 and April 2023, 24 patients were enrolled; 1 patient never started therapy and was excluded from the analysis. Median age was 70 years (range 41-88 years); 11 patients received ≥3 lines of therapy. Seventy-eight percent (18/23) of patients experienced grade ≥3 adverse event (AE) regardless of attribution at any DL, with one grade 5 AE (pneumonitis possibly related to EV). The recommended phase II doses are SG 8 mg/kg with EV 1.25 mg/kg with granulocyte colony-stimulating factor support; MTDs are SG 10 mg/kg with EV 1.25 mg/kg. The objective response rate was 70% (16/23, 95% confidence interval 47% to 87%) with three complete responses; three patients had progressive disease as best response. With a median follow-up of 14 months, 9/23 patients have ongoing response including 6 responses lasting over 12 months.

CONCLUSIONS

The combination of SG + EV was assessed at different DLs and a safe dose for phase II was identified. The combination had encouraging activity in patients with mUC with high response rates, including clinically significant complete responses. Additional study of this combination is warranted.

EV-301 long-term outcomes: 24-month findings from the phase III trial of enfortumab vedotin versus chemotherapy in patients with previously treated advanced urothelial carcinoma

INTRODUCTION

This exploratory analysis evaluated efficacy and safety data for enfortumab vedotin versus chemotherapy over a median follow-up of ∼2 years from EV-301.

MATERIALS AND METHODS

Patients with locally advanced/metastatic urothelial carcinoma with prior platinum-containing chemotherapy and disease progression during/after programmed cell death protein 1/ligand 1 inhibitor treatment were randomized to enfortumab vedotin or chemotherapy (docetaxel, paclitaxel, vinflunine). Endpoints were overall survival (primary), progression-free survival (PFS), objective response, and safety.

RESULTS

In total, 608 patients were included (enfortumab vedotin, n = 301; chemotherapy, n = 307). With a median follow-up of 23.75 months, 444 deaths had occurred (enfortumab vedotin, n = 207; chemotherapy, n = 237). Risk of death was reduced by 30% with enfortumab vedotin versus chemotherapy [hazard ratio (HR) 0.70 (95% confidence interval [CI] 0.58-0.85); one-sided, log-rank P = 0.00015]; PFS improved with enfortumab vedotin [HR 0.63 (95% CI 0.53-0.76); one-sided, log-rank P < 0.00001]. Treatment-related adverse event rates were 93.9% for enfortumab vedotin and 91.8% for chemotherapy; grade ≥ 3 event rates were 52.4% and 50.5%, respectively. Grade ≥ 3 treatment-related decreased neutrophil count (14.1% versus 6.1%), decreased white blood cell count (7.2% versus 1.4%), and anemia (7.9% versus 2.7%) were more common with chemotherapy versus enfortumab vedotin; maculopapular rash (7.4% versus 0%), fatigue (6.8% versus 4.5%), and peripheral sensory neuropathy (5.1% versus 2.1%) were more common with enfortumab vedotin. Of special interest adverse events, treatment-related skin reactions occurred in 47.3% of patients receiving enfortumab vedotin and 15.8% of patients receiving chemotherapy; peripheral neuropathy occurred in 48.0% versus 31.6%, respectively, and hyperglycemia in 6.8% versus 0.3%.

CONCLUSIONS

After a median follow-up of ∼2 years, enfortumab vedotin maintained clinically meaningful overall survival benefit versus chemotherapy, consistent with findings from the EV-301 primary analysis; PFS and overall response benefit remained consistent. Adverse events were manageable; no new safety signals were observed.