EphrinB2: Expression of a novel potential target in renal cell carcinoma

Introduction

Renal cell carcinoma (RCC) is primarily managed by surgery with the use of systemic targeted therapy in a metastatic setting. Newer targeted therapeutic options are evolving; Eph-ephrin is a potential new pathway. The therapeutic potential of targeting the EphB4-EphrinB2 pathway has been demonstrated in many solid tumors; however, its expression in RCC has only been evaluated in a few studies with limited cases. We herein determine the immunohistochemical expression of EphrinB2 in RCC.

Methods

A tissue microarray comprising 110 cases of different histological subtypes of RCC and 10 normal kidney tissues were stained with monoclonal anti-EphrinB2 antibody (Abcam, AB201512). The tumor and endothelial cells expressing the EphrinB2 were examined and its expression was correlated with sex, histological subtypes, and tumor nodes metastasis (TNM) stage.

Results

Twenty cases of urothelial carcinoma and two unsatisfactory conventional clear cell RCC cases were excluded, and EphrinB2 expression was interpreted in the remaining 88 tumors. EphrinB2 was expressed in 42 out of 88 tumors (47.7%) and was negative in the normal renal parenchyma. There was a statistically significant difference in the expression of EphrinB2 in males (55%) and females (32%). However, no such difference of expression was noted for the histological subtypes and the stages. Half (51%) of Stage 1 (n = 30) and Stage 2 (n = 11) tumors showed EphrinB2 positivity.

Conclusions

EphrinB2 is expressed in approximately half of RCC cases. EphrinB2 expression in the early stage cancer might indicate its induction as an early event.

EphrinB2 Inhibition and Pembrolizumab in Metastatic Urothelial Carcinoma

PURPOSE

Patients with metastatic urothelial carcinoma have poor prognosis after failure of standard first-line chemotherapy. Immune check point programmed death 1-programmed death ligand 1 antibodies have low response rates and thus there exists a major unmet need.

MATERIALS AND METHODS

In this phase II trial, patients with metastatic urothelial carcinoma that recurred or progressed after platinum-based chemotherapy received soluble EphB4-human serum albumin (sEphB4-HSA) in combination with pembrolizumab. The primary end points were tolerability and overall survival (OS). The secondary end points were progression-free survival (PFS), objective response rate (ORR), duration of response, and toxicity. The expression of sEphB4-HSA target EphrinB2 was correlated with outcomes.

RESULTS

Seventy patients were enrolled. The median follow up was 22.9 months (range, 1.3-54.7). The regimen had acceptable toxicity. In the intent-to-treat analysis (N = 70), the median OS was 14.6 months (95% CI, 9.2 to 21.5). Twenty-six (37%) patients had an objective response (95% CI, 26 to 48). The median PFS was 4.1 (95% CI, 1.5 to 5.7) months. Forty-six (66%) patients expressed EphrinB2, and among them, the median OS was 21.5 months (95% CI, 12.4 to not reached), the ORR was 52% (95% CI, 37 to 67), including a complete response rate of 24% (11 of 46; 95% CI, 12 to 36). The median PFS was 5.7 (95% CI, 2.7 to 27.9) months. Response was maintained at 6, 12, and 24 months in 88%, 74%, and 69% of the patients, respectively.

CONCLUSION

The combination of sEphB4-HSA and pembrolizumab appears synergistic with improved OS and ORR compared with historical data for programmed death 1/programmed death ligand 1 monotherapy.

Phase II trial of soluble EphB4-albumin in combination with PD-1 antibody (pembrolizumab) in relapsed/refractory head neck squamous cell carcinoma

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Background: EphB4 receptor tyrosine kinase and its ligand EphrinB2 are highly induced in head neck squamous cell carcinoma (HN SCC) tumor cells and vessels, particularly in HPV negative tumors. Each are predictors for poor survival with worse prognosis when both are induced. EphB4 provides tumor cell survival and EphrinB2 inhibits immune cell invasion. Soluble EphB4-Alb blocks bidirectional signaling, enhances immune cell recruitment alone and when combined with PD-1 antibody. Methods: A phase II trial of sEphB4-Alb combined with pembrolizumab accrued HN SCC patients after failure of one or more prior regimens. IHC positivity for p16 was used as a surrogate for HPV infection. Treatment regimen was sEphB4-Alb 10 mg/kg weekly IV infusion with pembrolizumab 200 mg IV infusion every three weeks. Study endpoints were toxicity, overall response rates (ORR) and overall survival (OS). Response to therapy was based on RECIST 1.1 criteria. Patient tumor samples were collected at baseline with a 2nd biopsy at week 8 on therapy, for tissue analysis of PD-L1, EphrinB2 and other biomarkers. Results: Twenty-four patients were accrued to the phase II trial combination of sEphB4-Alb and pembrolizumab. Age, sex, prior treatment, HPV status, and response data are summarized in the table below. The most common toxicity was hypertension with 8 patients experiencing grade 3 HTN. No grade 4 or above toxicities were observed. Among HPV negative cases, partial and complete responses were observed in 6 of 14 patients (43%) with complete response (CR) observed in 3 of 6 responders. Additionally, rapid response was observed in 3 of 14 HPV negative patients. Response was associated with increase in immune markers on 2nd biopsy. Median overall and progression-free survival in all patients was 12.6 months and 8.6 months, respectively. Conclusions: 1. sEphB4-Alb was well tolerated in combination with PD-1 antibody. 2. sEphB4-Alb was associated with increased immune response to tumor, when combined with PD-1 antibody. 3. sEphB4-Alb appears to have substantial activity (including complete remission) when combined with PD-1 antibody in relapsed/refractory HPV negative HN SCC. Clinical trial information: NCT03049618. [Table: see text]