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eFFECTOR Initiates Dosing of eFT508 (tomivosertib) in a Phase 2 Add-on (CPI-A) Trial in Combination

SAN DIEGO, July 27, 2018 — eFFECTOR Therapeutics, Inc., a leader in the development of selective translation regulators (STRs) for the treatment of cancer, today announced that it has dosed the first patient in a Phase 2 clinical trial of eFT508 (tomivosertib), the company’s oral, small molecule inhibitor of MNK1/2, added on to patients already receiving an FDA-approved anti-PD-1 or anti-PD-L1 checkpoint inhibitor, which may include Keytruda, Opdivo, Tecentriq, Bavencio or Imfinzi. Patients taking one of these checkpoint inhibitors in an approved indication who are experiencing an insufficient response to checkpoint inhibitor therapy alone are eligible for enrollment in this study. At the time eFT508 is added, patients will continue to receive their existing checkpoint inhibitor therapy. The trial design enables testing of the combination of eFT508 with a checkpoint inhibitor in multiple important cancer indications, including non-small cell lung, urothelial, head and neck and hepatocellular cancer among others.

“Despite the unprecedented activity of checkpoint inhibitors, the majority of patients fail to achieve a sufficient response to checkpoint inhibitor monotherapy, creating a critical need for combinations that improve outcomes,” said Steve Worland, Ph.D., president and chief executive officer of eFFECTOR. “Because patients in this trial have already experienced an insufficient response to checkpoint inhibitors alone, it’s an ideal environment to demonstrate a potential benefit of adding eFT508 to continued checkpoint inhibitor treatment. In preclinical studies, eFT508 demonstrated synergies with immune checkpoint blockade, so we believe there is great potential for this trial design, which allows us to broadly combine eFT508 with any approved checkpoint inhibitor in multiple indications.”

In this checkpoint inhibitor add-on (CPI-A) trial, eFT508 treatment will be added to patients receiving an FDA-approved anti-PD-1 or anti-PD-L1 antibody in the approved indication. This trial will include patients who initially responded to their checkpoint inhibitor therapy but subsequently show initial signs of progression, patients whose best response after multiple cycles of therapy is stable disease, and patients whose first response is increasing tumor volume suggestive of imminent progressive disease. Stable disease includes patients who have experienced minor increases in tumor burden and those with reduced tumor burden that does not yet meet the RECIST criteria for an objective response. The primary endpoints of this trial will assess anti-tumor activity including objective response rate (ORR) and progression free survival (PFS), and the safety of eFT508 in combination with checkpoint inhibitors.

About eFT508 (tomivosertib) eFT508 (tomivosertib) is a selective translation regulator and is part of a new class of cancer treatments known as immunotherapies that are designed to harness the body’s own immune system in fighting cancer. eFT508 is a highly potent and selective, oral inhibitor of MNK1 and MNK2 (MNK1/2). MNK1/2 are terminal kinases in key oncogenic signaling pathways, including KRAS-BRAF-MEK-ERK, and are activated by the mitogen dependent protein kinases (MAPK) in multiple immune cell types. MNK1/2 integrate MAPK pathway signaling at the level of mRNA translation, resulting in decreased anti-tumor immune activity due to selective upregulation of several immune checkpoint receptors and specific immunosuppressive cytokines. eFT508 selectively blocks MNK1/2 driven mRNA translation, thereby promoting anti-tumor immune response. eFT508 is currently being evaluated as a monotherapy in a Phase 2 clinical trial in non-GCB DLBCL, study NCT02937675, and in a Phase 2 clinical trial in combination with avelumab, a PD-L1 checkpoint inhibitor, in relapsed or refractory micro satellite stable colorectal cancer (MSS CRC), study NCT03258398.

About eFFECTOR Therapeutics eFFECTOR Therapeutics is a clinical-stage biopharmaceutical company focused on pioneering the discovery and development of selective translation regulators as a new class of oncology drugs. The company’s investigational compounds are designed to restore the translational control of processes which tumors have hijacked for their benefit, while preserving normal cell function. eFFECTOR’s most advanced program focuses on the development of eFT508, a MNK1/2 inhibitor in development for the treatment of patients with solid tumors and lymphoma. The company has additional selective translation regulator programs currently in discovery and development and maintains global rights to all of its development programs. For more information visit

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