On December 2, 2020 Aptevo Therapeutics Inc. ("Aptevo" or the "Company") (NASDAQ:APVO), a clinical-stage biotechnology company focused on developing novel immuno-oncology therapeutics based on its proprietary ADAPTIR platform, reported that it has expanded its ADAPTIR bispecific platform technology to include a new multi-specific platform technology, ADAPTIR-FLEX (Press release, Aptevo Therapeutics, DEC 2, 2020, View Source [SID1234572091]). Aptevo also announced that it has developed a new bispecific candidate, APVO442, that uses ADAPTIR-FLEX platform technology. APVO442 is a unique T-cell engager designed to target PSMA (prostate specific membrane antigen) and CD3 with low affinity for the treatment of prostate cancer. Prostate cancer is one of the most common forms of cancer in men.
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ADAPTIR-FLEX expands Aptevo’s ability to create novel therapeutic multi-specific candidates with the potential of exhibiting a wide variety of mechanisms of action. The new ADAPTR-FLEX platform technology enables the design of candidates that have modified affinity and valency to a target, which has the potential to improve specificity, tumor targeting, and therapeutic benefit with application to multiple hematologic and solid tumors. ADAPTIR-FLEX utilizes the same IgG-backbone and linkers found in ADAPTIR, but in a heterodimeric format, while retaining good manufacturability attributes and extended half-life that may enable improved dosing regimens in clinical development.
Aptevo also announced that it has developed a new bispecific candidate, APVO442, that utilizes ADAPTIR-FLEX platform technology targeting PSMA and CD3 for the treatment of prostate cancer. There has been early clinical validation of the combination of PSMA x CD3 as a bispecific in clinical development. Aptevo designed the new bispecific candidate APVO442 to have two binding domains targeting PSMA, to potentially increase avidity (strength) of binding to the tumor antigen PSMA, with one binding domain to CD3 with reduced binding affinity to T cells demonstrated in vitro.
"We are very excited about the launch of our second platform technology, ADAPTIR-FLEX, which expands our capability to design candidates with multiple new mechanisms of action, with potential best-in-class attributes," said Mr. Marvin White, President and CEO of Aptevo. "Recently, we had two patients in cohort 6 of our phase 1 APVO436 clinical trial achieve complete remission, which strengthened our resolve around the capabilities of our ADAPTIR platform technology. Our new bispecific candidate APVO442, built on ADAPTIR-FLEX, is a unique T-cell engager targeting PSMA and CD3 for the treatment of prostate cancer, and we are optimistic about the potential outcomes for patients impacted by these tumors," concluded Mr. White.
"The low affinity to CD3 and increased binding strength to PSMA are designed to potentially achieve better biodistribution to PSMA-positive tumors. Reducing the affinity to CD3 may have improved therapeutic benefit for treatment of prostate cancer compared to other CD3-based bispecifics targeting PSMA. In addition, this approach, using ADAPTIR-FLEX, can be applied to additional solid tumor types," said Jane Gross Ph.D., Chief Scientific Officer of Aptevo.
Aptevo believes that ADAPTIR-FLEX CD3-based candidates have the potential to demonstrate reduced production of cytokines consistent with other ADAPTIR-based T-cell engagers like observations made for APVO436 in preclinical studies. The reduced cytokine profile has been demonstrated for APVO442 in both in vitro and in vivo preclinical studies when T cells are challenged in the presence of drug and antigen-expressing tumors. This may reduce toxicities compared to those observed by other CD3-based T cell engagers with potential to achieve better efficacy and an increased therapeutic index in clinical development.
The therapeutic candidates APVO436, ALG.APV-527 and APVO603 based on the bivalent, bispecific ADAPTIR platform technology are advancing in clinical and preclinical development, respectively. Both the ADAPTIR platform technology and the ADAPTIR-FLEX platform technology will be used to develop therapeutic candidates based on desired mechanisms of action, to populate our portfolio with new bispecific and multi-specific protein therapeutics to potentially address unmet medical needs.