Checkmate Pharmaceuticals Presents Final Clinical Data for Phase 1b Study Evaluating Vidutolimod at The Society for Immunotherapy of Cancer (SITC) 36th Annual Meeting 

Rhea-AI Summary

Checkmate Pharmaceuticals (CMPI) announced promising results from its Phase 1b study of vidutolimod at the SITC Annual Meeting. The trial showed an overall response rate (ORR) of 23.5% when vidutolimod was combined with pembrolizumab, and 20.0% as a monotherapy. The combination therapy demonstrated a median duration of response of 25.2 months, indicating significant systemic antitumor activity in patients with PD-1 blockade-refractory melanoma. Safety monitoring indicated the treatment was well tolerated, with common side effects including chills and fatigue.

Positive

• Overall response rate (ORR) of 23.5% for the combination therapy with pembrolizumab.
• ORR of 20.0% for vidutolimod monotherapy.
• Median duration of response for combination therapy at 25.2 months.

Negative

• None.

Vidutolimod in combination with pembrolizumab demonstrated promising clinical activity in patients with PD-1 blockade-refractory melanoma with an ORR of 23.5% per RECIST v1.1

Vidutolimod also demonstrated monotherapy activity with an ORR of 20.0% per RECIST v1.1

CAMBRIDGE, Mass., Nov. 12, 2021 (GLOBE NEWSWIRE) -- Checkmate Pharmaceuticals, Inc. (NASDAQ: CMPI) (“Checkmate”), a clinical stage biotechnology company focused on developing proprietary technology to harness the power of the immune system to combat cancer, today announced the presentation of final clinical data from the Phase 1b study, CMP-001-001 (NCT02680184), of vidutolimod, an advanced generation Toll-like receptor 9 (TLR9) agonist, in combination with pembrolizumab or as a monotherapy at The Society for Immunotherapy of Cancer (SITC) 36th Annual Meeting taking place on November 10-14, 2021. 

“Our ongoing investigation of vidutolimod indicates promising clinical activity for patients with PD-1 blockade-refractory melanoma,” said Alan Fuhrman, interim President and Chief Executive Officer of Checkmate. Mr. Fuhrman added, “The RECIST response rates of 20% with vidutolimod monotherapy and 23.5% in combination with pembrolizumab are compelling, and the longer duration of response of 25.2 months in combination with PD-1 blockade provides a strong rationale for our ongoing development program.”

Final analysis: phase 1b study investigating intratumoral injection of Toll-like receptor 9 agonist vidutolimod ± pembrolizumab in patients with PD-1 blockade–refractory melanoma (Abstract #16269; poster #950; NCT02680184)

On Friday, November 12, 2021, during the Virtual Poster Hall Exhibit from 7:00am – 8:30pm ET, John M. Kirkwood, M.D., Director of the Melanoma and Skin Center at UPMC Hillman Cancer Center and Usher Professor of Medicine in the Division of Dermatology and Translational Science at the University of Pittsburgh School of Medicine, is presenting late-breaking final clinical data from the Checkmate-sponsored clinical trial of vidutolimod, either in combination with pembrolizumab or as monotherapy.

Final clinical data from the trial demonstrated that the combination of vidutolimod and pembrolizumab was well tolerated and resulted in an ORR of 23.5% according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. The study treatment induced deep and durable systemic antitumor responses in patients with melanoma who previously progressed on anti-PD-1 treatments.

“PD-1 blockade therapy has significantly improved clinical outcomes for many patients with cancer, although most patients still experience disease progression on anti−PD-1-therapy. Therapeutic alternatives for these patients are a large gap in the field, and critically needed,” said Dr. Kirkwood. “With clinically meaningful tumor regression we have observed both in injected and noninjected lesions, vidutolimod’s systemic effects hold the potential to enhance responsiveness and overcome resistance to immune checkpoint inhibitors. In addition, the substantially improved duration of response with the combination of vidutolimod and anti-PD-1 therapy provides strong rationale for further development of vidutolimod in combination with PD-1 blockade.”

Data were presented on 159 patients receiving combination therapy with vidutolimod and pembrolizumab. Two formulations of vidutolimod were evaluated, either polysorbate 20 at 0.01% (PS20, n=98) or x PS20 at 0.00167% (n=61). Based on the results, vidutolimod PS20 A 10 mg (schedule A) was selected as the Recommended Phase 2 Dose (RP2D) and schedule. Data were also presented on 40 patients who received vidutolimod monotherapy.

Key highlights from these clinical data as of the data cut-off of August 17, 2021 include:

Vidutolimod in combination with pembrolizumab

• The best ORR by RECIST v1.1 in patients who received vidutolimod PS20 A+ pembrolizumab was 23.5% (95% CI 15.5-33.1), including 7.1% (7/98) of patients with a complete response.
• Four additional patients who continued study therapy beyond initial disease progression achieved a partial response.
• Vidutolimod PS20 A 10 mg (schedule A) was selected as the RP2D.
• The Kaplan-Meier estimate for median duration of response was 25.2 months (95% CI8.7- not estimable [NE] in the 23 RECIST v1.1 responders).
• Among responding patients, non-injected target lesions regressed by a similar magnitude to injected target lesions.
• The most common treatment-related adverse events were chills, pyrexia, fatigue, nausea, vomiting and injection site pain.

Vidutolimod as a monotherapy

• In the 40 patients who received vidutolimod monotherapy, the best ORR by RECIST v1.1 was 20.0% (95% CI, 9.1-35.6).
• The median duration of response was 5.6 months (95% CI, 3.1-NE).  
• The most common treatment-related adverse events were chills, pyrexia, nausea, fatigue, headache, hypotension, and pruritus.
  

About Checkmate Pharmaceuticals 
 
Checkmate Pharmaceuticals is a clinical stage biotechnology company focused on developing its proprietary technology to harness the power of the immune system to combat cancer. Checkmate Pharmaceuticals’ product candidate, vidutolimod (CMP-001), is an advanced generation Toll-like receptor 9 (TLR9) agonist, delivered as a biologic virus-like particle utilizing a CpG-A oligodeoxynucleotide as a key component, designed to trigger the body’s innate immune system to attack tumors in combination with other therapies. Information regarding Checkmate Pharmaceuticals is available at www.checkmatepharma.com.

Availability of Other Information About Checkmate Pharmaceuticals

Investors and others should note that we communicate with our investors and the public using our website (www.checkmatepharma.com), our investor relations website (ir.checkmatepharma.com), and on social media (Twitter and LinkedIn), including but not limited to: investor presentations and investor fact sheets, U.S. Securities and Exchange Commission filings, press releases, public conference calls and webcasts. The information that Checkmate Pharmaceuticals posts on these channels and websites could be deemed to be material information. As a result, we encourage investors, the media, and others interested in us to review the information that is posted on these channels, including the investor relations website, on a regular basis. This list of channels may be updated from time to time on our investor relations website and may include additional social media channels. The contents of our website or these channels, or any other website that may be accessed from our website or these channels, shall not be deemed incorporated by reference in any filing under the Securities Act of 1933.

Forward Looking Statements  

Various statements in this release are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including words such as, but not limited to, “anticipate,” “believe,” “can,” “could,” “expect,” “estimate,” “design,” “goal,” “intend,” “may,” “might,” “objective,” “plan,” “predict,” “project,” “target,” “likely,” “should,” “will,” and “would,” or the negative of these terms and similar expressions or words, identify forward-looking statements. Forward-looking statements are based upon current expectations that involve risks, changes in circumstances, assumptions, and uncertainties. These statements include those regarding vidutolimod (CMP-001), including its development and therapeutic potential and the advancement of our clinical and preclinical pipeline; expectations regarding the results and analysis of data; and expectations regarding the timing, initiation, implementation and success of its planned and ongoing clinical trials for vidutolimod and the benefits and related implications of current and future partnerships and/or collaborations; and expectations regarding the Company’s use of capital, expenses and other financial results. Forward-looking statements should not be read as a guarantee of future performance or results and may not be accurate indications of when such performance or results will be achieved. These forward-looking statements are subject to risks and uncertainties, including those related to the development of our product candidate, including any delays in our ongoing or planned preclinical or clinical trials, the results from clinical trials, including the fact that positive results from a trial may not necessarily be predictive of the results of future or ongoing clinical trials, the impact of the ongoing COVID-19 pandemic on our business, operations, clinical supply and plans, the risks inherent in the drug development process, the risks regarding the accuracy of our estimates of expenses and timing of development, our capital requirements and the need for additional financing, and obtaining, maintaining and protecting our intellectual property. These and additional risks are discussed in the sections titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Quarterly Report on Form 10-Q for the period ending September 30, 2021 and in our Annual Report on Form 10-K for the year ending December 31, 2020, as filed with the Securities and Exchange Commission which are available on the Securities and Exchange Commission’s website at www.sec.gov, and as well as discussions of potential risks, uncertainties and other important factors in our subsequent filings with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and Checkmate undertakes no duty to update this information unless required by law.

FAQ

What were the results of the Checkmate Pharmaceuticals Phase 1b study for CMPI?

The Phase 1b study reported an overall response rate (ORR) of 23.5% for the combination of vidutolimod and pembrolizumab, and an ORR of 20.0% for vidutolimod as a monotherapy.

What is the duration of response for vidutolimod in the clinical trial?

The combination of vidutolimod with pembrolizumab showed a median duration of response of 25.2 months.

When did Checkmate Pharmaceuticals present the vidutolimod clinical data?

The final clinical data was presented at the SITC 36th Annual Meeting on November 12, 2021.

What are the common side effects associated with vidutolimod?

Common treatment-related side effects include chills, fatigue, nausea, and injection site pain.