Clinical Data from Ongoing Phase 1/2 Trial of IMO-2125 in anti-PD-1 Refractory Melanoma to be presented Sunday, September 10 at the European Society for Medical Oncology Congress (ESMO) in Madrid, Spain

CAMBRIDGE, MA and EXTON, PA, USA I September 08, 2017 I Idera Pharmaceuticals, Inc. (NASDAQ:IDRA), a clinical-stage biopharmaceutical company developing toll-like receptor and RNA therapeutics for patients with cancer and rare diseases, today is reporting new pre-clinical data from its ongoing intratumoral IMO-2125 development program at the Third Annual CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference being held in Frankfurt, Germany.

In the poster presentation entitled, “Intratumoral IMO-2125 Treatment in Combination with Anti-CTLA4 mAB Induces Durable Anti-Tumor Reponses Associated with Tumor-Specific Memory in Preclinical Studies,” presented by Daqing Wang, Ph.D., Principal Scientist & Group Leader, Idera Pharmaceuticals, demonstrated that intratumoral injections of IMO-2125 enhance anti-tumor responses in combination with CTLA4 blockade.  Further this study demonstrated the combination of IMO-2125 and anti-CTLA4 achieves prolonged, durable anti-tumor effect.

In this study, mice whose tumors completely regressed survived more than one year after the combination treatment was administered.  These animals maintained anti-tumor responses upon tumor re-challenge indicative of memory T-cell induction by the combination of IMO-2125 and anti-CTLA4.  Additionally, IMO-2125 delivered intratumorally has been shown to mediate tumor microenvironment changes including infiltration of T-cells and immune checkpoint gene up-regulation.

“These findings further support our current clinical trials which are designed to demonstrate that the combination of intratumoral IMO-2125 and Ipilimumab provides an opportunity to break the resistance to anti-PD-1 therapy and lead to durable effect in this patient population, one that clearly represents a significant unmet need in immuno-oncology,” stated Joanna Horobin, C.B., Ch.B., Idera’s Chief Medical Officer.  “We look forward to presenting further data from our ongoing clinical trial this weekend at ESMO as well as additional translational data from our trials at a future medical conference later this year.”

A copy of the poster presentation is currently available on Idera’s corporate website at http://www.iderapharma.com/our-approach/key-publications/.

Investor Event and Webcast
Idera will host a conference call and live webcast on Monday, September 11 at 9:00 A.M. EDT to review the data being presented here as well as at ESMO along with discussion of next steps for the IMO-2125 development program.  To participate in the conference call, please dial (844) 882-7837 (domestic) and (574) 990-9824 (international).  The webcast can be accessed live or in archived form in the “Investor’s” section of the company’s website at www.iderapharma.com.  The company plans to post a slide presentation on Monday, September 11, 2017 to the Idera corporate website in the “Investors” section which will be referenced during the conference call.

About IMO-2125 
IMO-2125 is a toll-like receptor (TLR) 9 agonist that received orphan drug designation from the FDA in 2017 for the treatment of melanoma Stages IIb to IV. It signals the immune system to create and activate cancer-fighting cells (T-cells) to target solid tumors in refractory melanoma patients. Currently approved immuno-oncology treatments for patients with metastatic melanoma, specifically check-point inhibitors, work for some but not all, as many patients’ immune response is missing or weak and thus they do not benefit from the checkpoint therapy making them so-called “refractory”. The combination of ipilimumab and IMO-2125 appears to activate an immune response in these patients who have exhausted all options. Intratumoral injections with IMO-2125 is designed to selectively enable the T-cells to recognize and attack cancers that remained elusive and unrecognized by the immune system exposed to checkpoint inhibitors alone, while limiting toxicity or impact on healthy cells in the body.

About Metastatic Melanoma
Melanoma is a type of skin cancer that begins in a type of skin cell called melanocytes. As is the case in many forms of cancer, melanoma becomes more difficult to treat once the disease has spread beyond the skin to other parts of the body such as by through the lymphatic system (metastatic disease). Because melanoma occurs in younger individuals, the years of life lost to melanoma are also disproportionately high when compared with other cancers.  Although melanoma is a rare form of skin cancer, it comprises over 75% of skin cancer deaths.  The American Cancer Society estimates that there were approximately 76,000 new invasive melanoma cases and 10,000 deaths from the disease in the USA in 2016.  Additionally, according to the World Health Organization, about 132,000 new cases of melanoma are diagnosed around the world every year.

About Idera Pharmaceuticals
Harnessing the approach of the earliest researchers in immunotherapy and the company’s vast experience in developing proprietary immunology platforms, Idera’s lead development program is focused on priming the immune system to play a more powerful role in fighting cancer, ultimately increasing the number of people who can benefit from immunotherapy. Idera continues to invest in research and development, and is committed to working with investigators and partners who share the common goal of addressing the unmet needs of patients suffering from rare, life-threatening diseases. To learn more about Idera, visit www.iderapharma.com.

SOURCE: Idera Pharmaceuticals