ASCO 2018: Updated Results from the Enfortumab Vedotin Phase 1 (EV-101) Study in Patients with Metastatic Urothelial Cancer

Chicago, IL ( Cisplatin-based chemotherapy remains the standard of care for patients with metastatic or advanced urothelial carcinoma (UC). In the past few years, multiple immune checkpoint inhibitors (ICI’s) have been approved in the 2nd line setting or in patients who are not eligible for cisplatin-based therapy – but none, as of yet, have replaced cisplatin based chemotherapy as it continues to have good upfront efficacy. 

Yet, in the 2nd line setting, prior chemotherapeutic agents have had abysmal results and patients have had limited options. Even with the introduction of these ICI’s, while 15-20% may benefit from durable response, the remaining 80% will not. So, unfortunately, the prognosis for these patients remains quite poor. Novel agents in this space, especially outside the saturated ICI pathway, are needed – particularly to target the 80% that will not respond. 

Enfortumab vedotin (EV) is one such novel agent that is showing great promise. It is an antibody–drug conjugate that delivers a microtubule-disrupting agent (similar to chemotherapeutic agents) to tumors expressing Nectin-4, which is a protein highly overexpressed in most urothelial cancers – it was found to be expressed in 93% of mUC samples (Petrylak et al. JCO 2017). Hence, it is transported primarily to UC cells rather than normal tissue. 

Preliminary results of the EV-101 study (NCT02091999) suggest that EV is active and tolerable at the recommended phase II dose (RP2D) of 1.25mg/kg. Daniel Petrylak, MD had previously presented this phase – Cohort 4 (highest dose) showed good tolerability and best efficacy. 

UroToday ASCO2018 EV 101

Here Rosenberg provides updated results from patients with mUC treated at this RP2D – it is still the phase II results that he is reporting. This includes patients in cohort 4 and part C (ICI-treated mUC patients). Part B is enrolling currently.

At the time of the talk, 155 patients with metastatic UC (mUC) have been treated. Of these, 112 received EV at RP2D, and these are the patients being presented today.

Baseline characteristics of these patients: 
-Median age 67 yr [range 24–86])
-Male 73%
-92% Caucasian
-ECOG PS 0 (32%) or 1 (68%)
-50% had GFR < 60 mL/min
-Bladder was the primary tumor site in 84 pts (75%) – 25% had upper tract disease
-Metastatic burden, 32 (29%) had liver metastases (LM); 48% lung, 19% lymph node only
-94% had received prior platinum chemotherapy
-63% received ≥2 prior therapies in the metastatic setting, including 79% who had a an immune checkpoint inhibitor (ICI)

In terms of safety and tolerability, EV was generally well tolerated

  • Grade ≤2 fatigue (54%) was the most commonly reported treatment-related AE (TRAE)
  • The most common Grade ≥3 AEs were anemia (8%), hyponatremia (7%), urinary tract infection (7%), and hyperglycemia (6%)
  • They are focusing on hyperglycemia as a specific AE related to EV
  • Four pts experienced a fatal TRAE (respiratory failure, urinary tract obstruction, diabetic ketoacidosis, multi-organ failure)
In terms of clinical response, confirmed complete response (CR) and partial responses (PRs) were observed in 4% and 37% of patients, respectively; ORR = 41%. Additional stable disease was seen in 30% of patients.

Waterfall plot below highlights these impressive results:

UroToday ASCO2018 Change in Tumor Burden from Baseline

There was no difference in patients with primary bladder vs. primary UTUC.

Response to therapy occurred early – median time to response: 1.68 months. The median duration of response: 5.75 months.

In subpopulations: 

  • Prior ICI: 40% ORR
  • ICI naïve: 43% ORR
  • Liver mets with prior ICI: 39%
The last population is very exciting! It is hard to see this kind of response in these patients.

Survival data:
-Median PFS was 5.4 months. 
-Median OS was 13.6 months – but this is still very immature as many patients are still early in their treatment. OS at 6 months was 74.4%; at 12 months 56.3%.

This appears to be a very promising drug in the second or third line. Enfortumab vedotin has encouraging ORR and PFS in heavily pretreated patients with mUC, including pts with LM and prior CPI treatment – these are patients with limited alternatives. 

** Based on these results, EV has been granted FDA Breakthrough Therapy designation for patients with mUC who have received prior ICI**

Interesting, mentioned in the slides but not by the speaker, EV can be given with much less baseline renal function – and may have a role earlier in the disease course! 50% of patients have GFR <60!

It is currently being evaluated in 3 additional studies:

1. EV-103: Phase 1 study EV+ICI in patients with locally advanced or mUC
2. EV-201: Phase 2 study of EV in patients with locally advanced or mUC who have received prior ICI and platinum-based chemotherapy (or have been platinum-ineligible
3. EV-301: Phase 3 study of EV versus 2nd-line standard of care chemotherapy (taxane or vinflunine) in advanced or mUC who have failed platinum-based chemotherapy and ICI

Presented by: Jonathan E. Rosenberg, MD, Memorial Sloan Kettering Cancer Center

Co-Authors: Srikala S. Sridhar, Jingsong Zhang, David C. Smith, Joseph D. Ruether, Thomas W. Flaig, Joaquina Celebre Baranda, Joshua Michael Lang, Elizabeth R. Plimack, Randeep S. Sangha, Elisabeth I. Heath, Jaime R. Merchan, David I. Quinn, Sandy Srinivas, Matthew I. Milowsky, Chunzhang Wu, Elaina M. Gartner, Amal Melhem-Bertrandt, Daniel Peter Petrylak

Author Information: Memorial Sloan Kettering Cancer Center, New York, NY; Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL; University of Michigan, Ann Arbor, MI; Tom Baker Cancer Centre, Calgary, AB, Canada; University of Colorado Comprehensive Cancer Center, Aurora, CO; University of Kansas Cancer Center, Fairway, KS; University of Wisconsin Carbone Cancer Center, Madison, WI; Fox Chase Cancer Center, Philadelphia, PA; Cross Cancer Institute, Edmonton, AB, Canada; Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, MI; University of Miami, Miami, FL; University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA; Stanford University, Stanford, CA; UNC School of Medicine, Chapel Hill, NC; Astellas Pharma, Inc., Northbrook, IL; Seattle Genetics, Inc., Bothell, WA; Yale School of Medicine, New Haven, CT

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, twitter: @tchandra_uromd at the 2018 ASCO Annual Meeting - June 1-5, 2018 – Chicago, IL USA

Read a Review on Abstracts 4503-4505 by Andrea B. Apolo, MD Nonimmunotherapy Strategies in Advanced Bladder Cancer