Exicure Presents Positive Clinical Data with Cavrotolimod at The Society for Immunotherapy of Cancer (SITC) 35th Anniversary Annual Meeting

The Phase 1b dose-escalation stage was designed to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of cavrotolimod alone and in combination with pembrolizumab, and to identify a recommended Phase 2 dose. Cavrotolimod was dosed intratumorally once weekly for 8 weeks and subsequently once every 3 weeks. Following an initial cavrotolimod monotherapy period, pembrolizumab was initiated at week 3 and dosed in combination with cavrotolimod once every 3 weeks. The Phase 1b stage enrolled patients with locally advanced or metastatic melanoma (n=10), Merkel cell carcinoma (n=5), cutaneous squamous cell carcinoma (n=2), head and neck squamous cell carcinoma (n=2), and leiomyosarcoma (n=1).

Updated data from the Phase 1b stage demonstrated that the combination of cavrotolimod and pembrolizumab continued to be well tolerated, with a confirmed overall response rate (ORR) of 21% (4/19 patients) according to RECIST v1.1 criteria. The combination immunotherapy regimen induced durable and systemic anti-tumor responses in patients with advanced solid tumors who previously progressed on anti-PD-1 therapy. At the time of enrollment in the clinical trial, 85% of patients were experiencing progressive disease despite treatment with PD-1 blockade and 65% of patients had been treated with 2 or more lines of systemic therapy.

Highlights from the Phase 1b Dose-Escalation Stage

- The RECIST-confirmed ORR was 21% (4/19 patients) overall in the Phase 1b dose-escalation stage, reflecting 1 complete response and 3 partial responses.

- In the highest cavrotolimod dose cohort (32 mg), which was selected as the Phase 2 dose, the RECIST-confirmed ORR was 33% (2/6 patients).

- Responses were durable and ongoing at the time of data analysis, with progression-free survival exceeding 6 months in all 4 responders and 16 months in 2 responders.

- 85% of patients overall (17/20 patients) and 75% of responders (3/4) were progressing on anti-PD-1 therapy at the time of trial enrollment.

- Systemic (abscopal) effects were observed, with shrinkage of regional or distant noninjected tumors.

- The majority (98%) of treatment-related adverse events were grade 1 or grade 2. No dose-limiting toxicities and no treatment-related serious adverse events were reported in the Phase 1b stage. The most common adverse events were flu-like symptoms and injection site reactions, consistent with other adverse events experienced with local and systemic immune activation associated with TLR9 agonism.

Details of the poster presentation are as follows:

Title: Safety and preliminary efficacy of intratumoral cavrotolimod (AST-008), a spherical nucleic acid TLR9 agonist, in combination with pembrolizumab in patients with advanced solid tumors

Authors: Steven J. O’Day, Cesar A. Perez, Trisha M. Wise-Draper, Glenn J. Hanna, Shailender Bhatia, Ciara M. Kelly, Theresa M. Medina, Douglas E. Laux, Adil Daud, Sunandana Chandra, Montaser Shaheen, Ling Gao, Melissa A. Burgess, Leonel Hernandez-Aya, Emil M. deGoma, Weston L. Daniel, Douglas E. Feltner, Laurel Sindelar, Robert E. Michel, Alice S. Bexon, Martin Bexon, and Mohammed M. Milhem

Poster/Abstract Number: 423

The abstract and poster will be available on the SITC website once the conference begins on Monday, November 9 at 8:00 a.m. EST. The poster will also be made available on the Exicure website.

Live Q&A will take place Wednesday, November 11 from 5:15–5:45 p.m. EST and Friday, November 13 from 4:40–5:10 p.m. EST.

About Exicure, Inc.

Exicure, Inc. is a clinical-stage biotechnology company developing therapeutics for neurology, immuno-oncology, inflammatory diseases and other genetic disorders based on our proprietary Spherical Nucleic Acid, or SNA technology. Exicure believes that its proprietary SNA architecture has distinct chemical and biological properties that may provide advantages over other nucleic acid therapeutics and may have therapeutic potential to target diseases not typically addressed with other nucleic acid therapeutics. Exicure is in preclinical development of XCUR-FXN an SNA–based therapeutic candidate, for the treatment of Friedreich’s ataxia (FA). Exicure's therapeutic candidate cavrotolimod is in a Phase 1b/2 trial in patients with advanced solid tumors. Exicure is based in Chicago, IL and in Cambridge, MA.

For more information, visit Exicure’s website at www.exicuretx.com.

Exicure Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements in this press release other than statements of historical fact could be deemed forward looking including, but not limited to, statements regarding the company’s ongoing Phase 1b/2 clinical trial of cavrotolimod (AST-008) . The forward-looking statements in this press release speak only as of the date of this press release, and the company undertakes no obligation to update these forward-looking statements. Forward-looking statements are based on management’s current beliefs and assumptions that are subject to risks and uncertainties and are not guarantees of future performance. Actual results could differ materially from those contained in any forward-looking statement as a result of various factors, including, without limitation: the risks that the ongoing COVID-19 pandemic may disrupt the company’s business and/or the global healthcare system more severely than it has to date or more severely than anticipated, which may have the effect of impacting or delaying the company’s ongoing Phase 1b/2 clinical trial; unexpected costs, charges or expenses that reduce the company’s capital resources; the company’s preclinical or clinical programs do not advance or result in approved products on a timely or cost effective basis or at all; the results of early clinical trials are not always being predictive of future results; the cost, timing and results of clinical trials; that many drug candidates do not become approved drugs on a timely or cost effective basis or at all; the ability to enroll patients in clinical trials; possible safety and efficacy concerns; regulatory developments; risks that preliminary results from clinical trials are not necessarily predictive of future clinical trial results; and the ability of the company to protect its intellectual property rights. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the section titled “Risk Factors” in the company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2020, as updated by the company’s subsequent filings with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and the company undertakes no duty to update this information, except as required by law.

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