by Dr. C.H. Weaver M.D. updated 2/2021
There are currently no approved treatment options for patients with advanced bladder cancer after standard chemotherapy and immune treatments, but the results of a phase II clinical trial presented at the June 2019 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago led to the U.S. Food and Drug Administration (FDA) granting Breakthrough Therapy Designation to enfortumab vedotin (EV) for patients with locally advanced or metastatic urothelial (bladder) cancer who were previously treated with checkpoint inhibitors (1) and now full FDA approval.
Enfortumab vedotin is a novel precision cancer medicine known as an antibody drug conjugate, a type of therapy that combines an antibody that targets a specific protein on the surface of tumor cells with a payload of powerful chemotherapy. It is composed of an anti-Nectin-4 monoclonal antibody attached to a microtubule-disrupting agent, MMAE. Enfortumab vedotin targets Nectin-4, a cell adhesion molecule identified as an ADC target which is expressed on many solid tumors. This antibody is chemically linked with an agent that penetrates the tumor cell and destroys its structure.
Padcev was approved by the U.S. Food and Drug Administration in December 2019 and is indicated for the treatment of adult patients with locally advanced or metastatic urothelial cancer who have previously received a programmed death receptor-1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitor and a platinum-containing chemotherapy before (neoadjuvant) or after (adjuvant) surgery or in a locally advanced or metastatic setting.
What does the data show?
In the original multi-institutional clinical trial reported at ASCO 2019 Padcev produced responses in 44% of patients with locally advanced or metastatic urothelial cancer who had been previously treated with chemotherapy and checkpoint inhibitors. Among 125 patients who had received both standard chemotherapy plus a checkpoint inhibitor and Padcev, 12% had a complete response with no detectable sign of cancer and the median overall survival was 11.7 months. Notably, 38% of people whose cancer had spread to the liver responded to the treatment.
Padcev Superior to Chemotherapy in advanced Urothelial Cancers
Padcevoutperformed chemotherapy on key survival metrics in a phase 3 trial, extending the life of patients with previously treated advanced urothelial cancer by nearly four months, compared with standard care.
Platinum-containing chemotherapy sequenced with programmed cell death protein-1/programmed death ligand 1 (PD-1/L1) inhibitors is the standard of care for patients with locally advanced or metastatic urothelial carcinoma (la/mUC).
Padcev is a U.S. FDA-approved antibody-drug conjugate that targets Nectin-4 — is a cell adhesion molecule highly expressed in urothelial cancer. In phase 1 and 2 studies, the drug demonstrated a consistent clinical benefit with response rates of approximately 40%.
Investigators reported the results of a phase 3 clinical study in 608 patients with histologically confirmed advanced urothelial cancer who had previously received platinum-containing chemotherapy, and whose disease had progressed during or after PD-1/L1 checkpoint inhibitor treatment.
The EV-301 Trial - EV-301 was a phase 3 clinical trial designed to evaluate Padcev versus physician's choice of chemotherapy (docetaxel, paclitaxel or vinflunine) in approximately 600 patients with locally advanced or metastatic urothelial cancer who were previously treated with a PD-1 or PD-L1 inhibitor and platinum-based therapies. In September 2020 the phase 3 trial met its primary endpoint of improving overall survival compared to chemotherapy. Padcev significantly delayed cancer progression and improved overall survival with a 30 percent reduction in risk of death. (4)
Padcev treated patients more likely to respond to treatment and experience delayed cancer progression-free survival. Most importantly overall survival improved with Enfortumab; 12.9 months, which as 3.9 months longer than what was seen in patients treated with chemotherapy.
The most common side effects for patients taking Padcev were fatigue, peripheral neuropathy decreased appetite, rash, hair loss, nausea, altered taste, diarrhea, dry eye, itching and dry skin.
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