On June 1, 2026 NextCure, Inc. (Nasdaq: NXTC), a clinical-stage biopharmaceutical company committed to discovering and developing novel therapies to treat cancer, and Simcere Zaiming Pharmaceutical Co., Ltd., (Simcere Zaiming) an oncology-focused biopharmaceutical company and a subsidiary of Simcere Pharmaceutical Group Ltd (HKEX: 2096), reported the presentation of positive Phase 1 dose escalation data for SIM0505 at the American Society for Clinical Oncology (ASCO 2026) in Chicago, IL (poster #246). SIM0505 is an investigational antibody drug conjugate (ADC) targeting Cadherin-6 (CDH6) with a proprietary topoisomerase 1 inhibitor (TOPOi) payload. NextCure plans to host a virtual KOL Event on Tuesday, June 2, 2026 (register here) to review these data.

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Platinum-resistant ovarian cancer (PROC) and uterine serous carcinoma (USC) represent two of the most challenging gynecologic malignancies. In PROC, once platinum resistance develops, response rates to available therapies drop to as low as 10–25%, with a median overall survival of approximately 11 months. USC, while accounting for only 10% of uterine cancers, is responsible for about 40% of uterine cancer deaths, with 5-year survival falling to 33% in advanced-stage disease. Taken together, these two cancers represent a persistent and significant unmet need for more effective treatment options.1-3

The Phase 1 dose escalation study (NCT06792552) evaluated SIM0505 in 59 heavily pre-treated cancer patients, with a data cutoff of April 07, 2026. Patients in the U.S. (n=25) and China (n=34) received SIM0505 at doses ranging from 1.6 mg/kg to 9.6 mg/kg, regardless of CDH6 expression.

Positive efficacy data were observed, with an objective response rate (ORR) of:

● 55% (11/20) for gynecologic cancers (ovarian cancer and USC)
● 52.9% (9/17) for ovarian cancer
● 66.7% (2/3) for USC
● Responses were observed across a range of CDH6 expression
ORRs, above, are reported for patients within therapeutic dose cohorts of 4.8 – 8.0 mg/kg who had a minimum 12 weeks of follow-up at the data cut-off, and were determined by best response according to RECIST 1.1 criteria. Of the nine (9) ovarian patients with partial response (PR), there was one unconfirmed PR and one PR pending confirmation at next follow-up scan.

"Positive Phase 1 data presented at ASCO (Free ASCO Whitepaper) 2026 validate our conviction in SIM0505 as a potential best-in-class CDH6-directed therapy for gynecologic cancers. Meaningful response rates at 12 weeks, alongside a manageable safety profile, give us strong confidence in this program and reinforce our enthusiasm for the ongoing dose optimization study. We believe SIM0505 has broad potential in gynecologic cancers and beyond, and these data put us on a solid track toward pivotal studies and our goal of bringing this treatment to patients," said Michael Richman, President and CEO of NextCure.

"Data presented at ASCO (Free ASCO Whitepaper) 2026 underscore the promise of our ADC platform and SIM0505, purpose-designed to deliver better efficacy, safety and tolerability, combining a carefully selected EC1 CDH6 epitope with our proprietary CPT116 topoisomerase payload. These results validate the science behind the SIM0505 construct and the accelerating pace of the global development program. Together with our partner, we remain deeply committed to advancing innovative medicines for patients facing hard-to-treat cancers," said Renhong Tang, PhD, CEO of Simcere Zaiming.

"Treatment of gynecologic cancers has advanced meaningfully in recent years, yet the need for safer and more effective treatments remains real. CDH6 is an attractive target given its expression across ovarian, uterine, and other solid tumors. ADCs directed at this target have the potential to deliver the deeper, more durable responses these patients need. The early response rates observed for SIM0505 at ASCO (Free ASCO Whitepaper) 2026 are encouraging, and I believe the safety profile is manageable in routine clinical practice. I am enthusiastic about this program and its potential to advance the standard of care in gynecologic cancers," said Udayan Guha, MD, PhD, Chief Medical Officer of NextCure.

ASCO Poster Overview: "Phase 1, multicenter, first-in-human (FIH) global study of SIM0505, an anti-CDH6 (CDH6) antibody-drug-conjugate (ADC) in patients with advanced solid tumors"

Table 1: Study Subject Overview:

All Patients

Baseline Characteristics

(n=59)

Age, years: median (range)

58 (42-78)

Sex, %: Male/Female

3.4%/96.6%

Race, n (%)

Asian

34 (57.6%)

Black or African American

3 (5.1%)

White

20 (33.9%)

Other

2 (3.4%)

Tumor Type, n (%)

Ovarian

46 (78.0%)

USC/other endometrial

10 (16.9%)

Renal cell carcinoma (RCC)

3 (5.1%)

ECOG performance status, n (%)

0

16 (27.1%)

1

43 (72.9%)

Prior systemic anti-cancer regimen: median (range)

5 (1-12)

Table 2: Efficacy Overview:

Patient Group

ORR*

All gynecologic patients (n=20)

55% (11/20)

• Ovarian cancer (n=17)

52.9% (9/17)

• USC (n=3)

66.7% (2/3)

*Reported for patients within therapeutic SIM0505 dose cohorts of 4.8 – 8.0 mg/kg who had a minimum 12 weeks of follow-up at the April 7, 2026 data cut-off, and were determined by best response according to RECIST 1.1 criteria. Of the nine (9) ovarian patients with PR, there was one unconfirmed PR and one PR pending confirmation at next follow-up scan.

Overall safety: Favorable overall data, potentially manageable in routine practice setting (n=59):

● Grade 1 and 2 treatment emergent adverse events (TEAEs) predominantly hematological, nausea and vomiting
● Grade 3 and 4 TEAEs predominantly hematological and manageable without primary prophylaxis for hematological toxicities
● Treatment related adverse events (TRAEs) requiring dose discontinuation: n=3
A full copy of the poster will be available on the NextCure website under the Investor Relations "Events & Presentations" tab following the presentation.

Virtual KOL Event

NextCure will host a virtual KOL Event to discuss the ASCO (Free ASCO Whitepaper) 2026 data.

● Date: June 2, 2026
● Time: 8:00 AM ET
● Registration Link: Click here
A replay of the webinar will be accessible on the Events page of the NextCure website for 90 days.

About SIM0505

SIM0505 is a novel ADC directed to CDH6, featuring a proprietary TOPOi payload. The ADC is designed for broad anti-tumor activity, fast systemic clearance and an improved potential therapeutic window. SIM0505 is being evaluated in an open-label, Phase 1 study (NCT06792552) for the potential treatment of advanced solid tumors, including ovarian cancer, with an emphasis on PROC. The U.S. Food and Drug Administration granted Fast Track Designation to SIM0505 for the treatment of PROC. NextCure holds exclusive global rights for SIM0505, excluding China, Hong Kong, Macau, and Taiwan which are retained by Simcere Zaiming.

About the Phase 1 Trial of SIM0505

SIM0505 is being evaluated in a global Phase 1 open-label, multicenter study (NCT06792552) with sites in the U.S. and China. The Phase 1 dose escalation segment has evaluated SIM0505, at dose levels from 1.6 mg/kg to 9.6 mg/kg, in heavily pre-treated cancer patients with solid tumors including gynecologic cancers and renal cell carcinoma. As of the April 7, 2026 data cutoff, 59 patients were enrolled without preselection for CDH6 expression. Follow-up is ongoing.

In May 2026, NextCure initiated a Phase 1 dose optimization segment in gynecologic cancers, initially focusing on patients with PROC. The global study is expected to enroll up to 120 patients, with initial doses of 5.6, 6.4 and 7.2 mg/kg, at sites in the U.S., Canada, the EU and China.

About Ovarian Cancer4-8

Ovarian cancer is the fifth leading cause of cancer-related death among women. It is characterized by vague, easily overlooked symptoms like bloating, pelvic pain, and frequent urination that often go undetected until late stage. Risk factors include age, family history, BRCA1/2 mutations, and hormone therapy use. The median age at diagnosis is 63, and the overall 5-year relative survival rate is 51.6% — though early-stage diagnosis carries a 5-year survival rate of 91.7%. As of 2022, an estimated 244,000 women were living with ovarian cancer in the United States.

About Uterine Serous Cancer2

Uterine serous carcinoma is a rare but highly aggressive subtype of endometrial cancer, accounting for approximately 10% of uterine cancers and about 40% of uterine cancer deaths. It typically arises in postmenopausal women, with abnormal or postmenopausal bleeding as the most common presenting symptom. Risk factors include advancing age, a history of breast cancer, tamoxifen use, and hereditary breast-ovarian cancer syndrome. More than half of patients present with stage III or IV disease at diagnosis, contributing to its disproportionate mortality burden.

(Press release, NextCure, JUN 1, 2026, View Source [SID1234666312])