SOUTH SAN FRANCISCO, Calif., May 29, 2020 (GLOBE NEWSWIRE) -- RAPT Therapeutics, Inc. (Nasdaq: RAPT), a clinical-stage, immunology-based biopharmaceutical companyfocused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in oncology and inflammatory diseases, today announced the presentation of a Trials in Progress poster for the ongoing seamless Phase 1/2 clinical trial of FLX475, a small molecule CCR4 antagonist in development for multiple tumor types. The poster was presented at the American Society of Clinical Oncology (ASCO) 2020.

The poster presentation detailed previously reported initial Phase 1 healthy volunteer data for FLX475 that demonstrated excellent safety, pharmacokinetics (PK) and target engagement. FLX475 is designed to block regulatory T cells from migrating to tumor sites, where they suppress immune system responses to cancer cells, without depleting regulatory T cells in the rest of the body nor immune cells required for an anti-tumor response. A robust pharmacodynamic (PD) assay measuring receptor occupancy on circulating regulatory T cells demonstrated that FLX475 achieved exposure levels over the targeted 75%, predicting maximal inhibition of regulatory T cell recruitment into tumors via CCR4 signaling. In addition, levels of FLX475 increased in a dose-proportional manner, with a strong PK/PD correlation observed between drug levels and receptor occupancy.

Building on these data, RAPT initiated a seamless Phase 1/2 study of FLX475. The Phase 1 portion of the trial was a standard dose escalation study in patients with many types of cancer, and the Phase 2 portion is evaluating FLX475 both as monotherapy and in combination with a checkpoint inhibitor in patients with charged tumors, which are tumors that express high levels of CCR4 ligands (CCL17 and CCL22), and have a high presence of regulatory T cells and CD8+ effector T cells. RAPT is currently enrolling the Phase 2 portion of the trial in patients with charged tumors, including non-small cell lung cancer, triple negative breast cancer, head and neck squamous cell carcinoma, cervical cancer as well as EBV-positive nasopharyngeal cancer and lymphomas.

We are pleased with our continued progress in clinical evaluation of FLX475 and remain encouraged by our early observations, said Brian Wong, M.D., Ph.D., President and CEO of RAPT Therapeutics. The previously reported checkpoint inhibitor-refractory patient with non-small cell lung cancer with a confirmed partial response in the Phase 1 part of this study continues to respond to FLX475 plus Keytruda, and is approaching the 1-year mark of study treatment. Our sites in the U.S., Australia and Asia continue to enroll patients and we remain on track to report results for both the Phase 1 and initial Phase 2 expansion cohorts in the second half of 2020.

The poster presented at ASCO can be viewed on the RAPT website under the Events and Presentation tab of the Investor Relations section here.

About FLX475FLX475 is a small molecule CCR4 antagonist designed to block the migration of regulatory T cells (Treg) specifically into tumors, but not healthy tissues. Tregrepresent a dominant pathway for downregulating the immune response, and may limit the effectiveness of currently available therapies such as checkpoint inhibitors. RAPT is developing FLX475 for the treatment of a broad range of charged tumors, which represent cancer types the company believes are most likely to respond to FLX475, where a large quantity of Tregcells are likely to be the cause of immune suppression within the tumor. FLX475 blocks the migration of Tregto the tumor, which may restore naturally occurring antitumor immunity and synergizing with a variety of both conventional and immune-based therapies, such as radiation, chemotherapy, checkpoint inhibitors, immune stimulators and adoptive T cell therapy.

AboutRAPT Therapeutics, Inc.RAPT Therapeutics is a clinical stage immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in oncology and inflammatory diseases. Utilizing its proprietary discovery and development engine, the Company is developing highly selective small molecules designed to modulate the critical immune drivers underlying these diseases. RAPT has discovered and advanced two unique drug candidates, FLX475 and RPT193, each targeting C-C motif chemokine receptor 4 (CCR4), for the treatment of cancer and inflammation, respectively. The Company is also pursuing a range of targets, including hematopoietic progenitor kinase 1 (HPK1) and general control nonderepressible 2 (GCN2), that are in the discovery stage of development.

Forward-Looking StatementsThis press release contains forward-looking statements. These statements relate to future events and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future performances or achievements expressed or implied by the forward-looking statements. Each of these statements is based only on current information, assumptions and expectations that are inherently subject to change and involve a number of risks and uncertainties. Forward-looking statements include, but are not limited to, statements about the clinical development of FLX475, the interpretation of preliminary observations from the Phase 1 cohort in FLX475 and the continued progress and timing of results from clinical trials of FLX475. Detailed information regarding risk factors that may cause actual results to differ materially from the results expressed or implied by statements in this press release may be found in RAPTs Form 10-Q filed with the Securities and Exchange Commission on May 14, 2020 and subsequent filings made by RAPT with the Securities and Exchange Commission. These forward-looking statements speak only as of the date hereof. RAPT disclaims any obligation to update these forward-looking statements.

RAPT Media Contact:Angela Bittingmedia@rapt.com(925) 202-6211

RAPT Investor Contact:Sylvia Wheelerswheeler@wheelhouselsa.com

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RAPT Therapeutics Announces Poster Presentation at the American Society of Clinical Oncology Virtual Scientific Program - GlobeNewswire