NECTIN4 Amplification Predicts Response to EV in Metastatic Urothelial Carcinoma

Niklas Klümper, MD, of University Hospital Bonn, highlights an analysis of NECTIN4 amplification as a biomarker for predicting response to enfortumab vedotin (EV) in metastatic urothelial carcinoma treatment, with comments on its implications for clinical practice and ongoing research efforts.

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Can you provide an overview of the context and significance of this study on NECTIN4 amplification and its implications for mUC treatment?

Dr. Klümper: We have heard about the excellent results of the anti-NECTIN4 antibody-drug conjugate (ADC), EV, for the treatment of metastatic urothelial cancer patients. However, there are currently no predictive biomarkers available to accurately predict responses to this new targeted therapy.

In the study we recently published in JCO, we demonstrated a significant biomarker signal for NECTIN4 amplification in predicting responses to anti-NECTIN4 ADC therapy. We know from other ADCs, such as HER2 ADCs, that ADC response correlates with target gene expression. However, this correlation had not been described for EV in clinical trials, as it was believed that all urothelial cancer patients express high levels of NECTIN4.

Last year, in Clinical Cancer Research, we reported that a substantial proportion of patients exhibit a loss or decrease in membranous NECTIN4 expression, which is necessary for EV binding throughout metastatic spread. We demonstrated that membranous NECTIN4 expression correlates with EV response.

In our current study, we examined NECTIN4 copy number alterations and found that NECTIN4 amplification is one of the most frequent copy number alterations in urothelial cancers, occurring in about 25% to 30% of cases. We showed that patients with NECTIN4 amplification have favorable outcomes on EV monotherapy. These patients maintain high membranous NECTIN4 expression throughout metastatic progression, and over 90% of those with amplification had an objective response to EV monotherapy, which is a remarkable biomarker signal.

This translates to prolonged progression-free and overall survival. The median progression-free survival in the NECTIN4 amplified EV-treated population exceeded 16 months, and median overall survival was not reached, with a 12-month survival rate of about 90%, compared to only 41% in the NECTIN4 non-amplified population.

Can you detail the NECTIN4-specific fluorescence in situ hybridization (FISH) assay developed in the study? How effective was it in predicting response to EV?

Dr. Klümper: We were able to establish an easy and straightforward NECTIN4 FISH assay with a custom available probe. In the standard care and molecular pathology settings, multiple FISH assays, such as HER2 FISH assays, are available for clinical routine. However, we were the first to establish a specific NECTIN4 FISH for tumor testing and demonstrated that identifying NECTIN4 amplification using FISH is robust. We validated FISH using next-generation sequencing and other microarray tests, confirming that our FISH assay is both robust and specific.

In our cohort of more than 100 patients treated with EV, we demonstrated that around 25% of the patients had NECTIN4 amplification, showing the strong biomarker signal mentioned earlier.

For clinical implementation, FISH assays would be the easiest to incorporate into standard care because they are straightforward, inexpensive, and easy to implement in smaller molecular pathology labs. We believe that a FISH assay is the best method for identifying NECTIN4 amplification, and it is less expensive than next-generation sequencing-based diagnostics of copy number alterations.

Are there any noteworthy limitations of your findings or of the analysis in general?

Dr. Klümper: The main limitation of our study is that the cohort we have assembled is retrospective. We are currently establishing a prospective validation cohort to confirm the biomarker signal in a prospectively assembled cohort. However, the retrospective nature of our study remains a significant limitation.

Another potential limitation is that we have included both primary urothelial cancer samples and metastatic samples, as metastatic biopsy samples were not available for the majority of patients. Despite this, we believe it is not a major limitation. We demonstrated in a small sub-cohort, where both primary and matched metastatic samples were available, that the NECTIN4 copy number status remains robust throughout metastatic evolution, with more than 90% of primary tumors retaining the NECTIN4 copy number alteration in the metastatic stage. Nevertheless, the retrospective nature is the most significant limitation, and we hope that other groups, along with our prospective validation cohort, can validate this finding.

We are also assembling a cohort of patients treated with EV/pembrolizumab to assess whether this biomarker is relevant in the combination setting. We believe this might be the case, as EV has higher single-agent activity than pembrolizumab. We hypothesize that patients with NECTIN4 amplification may be overrepresented in the complete response population from the EV-302 trial.

What potential does NECTIN4 amplification have as a biomarker in other cancer types beyond urothelial cancer?

Dr. Klümper: We have also demonstrated in our publication that NECTIN4 amplification is a frequently occurring genomic alteration across various solid cancers. It is commonly observed in lung cancer, breast cancer, and other disease types. Therefore, we believe that this biomarker could be of interest for these diseases, where NECTIN4-targeting drugs like EV are currently being tested in clinical trials. Although we do not yet have data on this, it would be exciting to see if this biomarker can drive rational NECTIN4-targeting drug development beyond urothelial cancer.