Science

Modular peptide cargo delivery by targeting CD40 enables ligandome driven, precision immunotherapy via the Adaptable Drug Affinity Conjugate (ADAC™) technology
A Mebrahtu², I Lauren¹, R Veerman³, A Kostakis¹, G Gucluler Akpinar³, O Andersson^4,5, L Gudmundsdotter³, T Furebring³, H Persson^2,5, P Dönnes³, J Rockberg², S Mangsbo^1,3
1Uppsala University, Uppsala, Sweden, ²Kungliga Tekniska Högskolan, Stockholm, Sweden, ³Strike Pharma AB, Uppsala, Sweden, ⁴Karolinska University, Stockholm, Sweden, ⁵SciLifeLab DDD platform

Agonistic anti-CD40 therapy has shown impressive efficacy in preclinical murine models, models inert to toxicity of high systemic drug exposure. Clinical data consist of pharmacodynamic responses reported as non-specific cytokine release, transient drop of CD40-expressing cells in blood and induction of co-stimulatory ligands/receptors on antigen-presenting cells, but so far clinically meaningful efficacy data on monotherapy use is lacking. Clinical data also indicate a bell-shaped dose-response curve, with excessive immune activation leading to immune exhaustion when combined with check-point inhibitors. Intratumoral route of administration, bispecific antibodies for tumor drug localization or Antibody-Drug Conjugates (ADCs) carrying antigenic cargo are or have been assessed, but have associated clinical utility enigmas. Herein we present a novel solution ensuring modular peptide delivery along with an efficient T cell priming strategy; a bivalent anti-CD40 agonistic antibody equipped with a peptide-binding single chain variable fragment (scFv) that binds a short peptide tag (pTag) in the low nM range. The resulting drug strategy makes use of synthetic long peptide production of any tumor-associated antigen (TAA) of choice where the pTag itself ensures simple conjugate production to the protein, through affinity linkage, leading to a final rapid in-hospital mixing step. Data suggest that the novel candidate drug (STRIKE2001), now developed based on the ADAC concept, retains similar agonistic activity in its bispecific, IgG2 format and does not inhibit CD40L binding to the CD40 protein. Data further show impressive expansion of endogenous tumor-specific T cells (as measured by tetramer staining), along with effective anti-tumor responses in the TC1 model. In addition, by using the subcutaneous delivery strategy CD40 agonist exposure to liver and spleen is vastly reduced, limiting systemic immune toxicity/exhaustion risks.

This poster received the CIMT 2022 Poster Award, Therapeutic Vaccines. Congratulations to all involved!

An agonistic CD40 bispecific antibody designed for flexible synthetic peptide-cargo delivery through an affinity interaction, a way to ensure optimal T cell activation

Ida Olsson ^1,3, Aman Mebrahtu ^2,3, Rosanne Veerman ³, Juan Astorga ⁴, Jimmy Ytterberg ¹, Annika Lindqvist ¹, Leif Dahllund ^4, Anders Olsson ⁴, Oskar Andersson ⁴, Johan Rockberg ^2,3, Helena Persson ^2,4, Sara Mangsbo ^1,3.
¹Uppsala University, Uppsala, Sweden, ²Kungliga Tekniska Högskolan, Stockholm, Sweden, ³Strike Pharma AB, Uppsala, Sweden, ⁴Karolinska University, Stockholm, Sweden

For efficient tumor recognition, CD8 T-cells rely on antigen presentation and costimulation performed by antigen presenting cells (APCs). Agonistic CD40 antibodies support the activation of APCs, leading to increased activation and antigen presentation. However, monotherapy of agonistic CD40 antibodies has failed to generate clinical effect, possibly due to the failure to account for the importance of antigen-presentation for efficient T cell activation.

This poster shows the use of ADAC technology in the development of a novel anti-CD40 antibody clone, STRIKE-1001, as a cancer-treatment vaccine candidate. The ADAC technology enables cargo-delivery via a non-covalent high-affinity interaction between a scFv (single-chain variable fragments fused recombinantly to the parental antibody, in this case the anti-CD40 antibody) and a peptide tag (pTag) enabling the agonistic CD40 antibody to deliver an antigen-related peptide cargo to APCs while maintaining a more flexible approach of cargo delivery compared to a traditional antibody drug conjugate (ADC).

Using phage display, STRIKE-1001 was generated and agonistic activity was confirmed. After adaptation to the bispecific format, STRIKE 2001, this selected clone shows developability characteristics on par with the parental antibody, retained agonistic activity on human dendritic cells and improved CD8⁺ and CD4⁺ T-cell proliferation in vivo.

Development of an Adaptable Drug Affinity Conjugate, targeting the CD40 protein, provides a flexible therapeutic peptide cargo delivery to dendritic (APC) cells

Ida Laurén ¹, Mohamed Eltahir ^1,3, Aman Mebrahtu ^2,3, Rosanne Veerman ³, Juan Astorga ⁴, Aljona Saleh ^1, Jimmy Ytterberg ^1, Annika Lindqvist ¹, Leif Dahllund ⁴, Anders Olsson ⁴, Oskar Andersson ⁴, Johan Rockberg ^2,3, Helena Persson ^2,4, Sara Mangsbo ^1,3.
¹ Uppsala University, Uppsala, Sweden, ² KTH Royal Institute of Technology, Stockholm, Sweden, ³ Strike Pharma AB, Uppsala, Sweden, ⁴ Karolinska University, Stockholm, Sweden

CD40 agonistic antibodies targeting antigen-presenting cells (APCs) rely on simultaneous presentation of an antigen for optimal efficacy since the co-stimulatory signal alone will not lead to T-cell activation. The ADAC technology platform utilizes a high-affinity interaction between a short non-immunogenic peptide-tag (pTag) and a single-chain fragment (scFv) of the antibody to enable attachment of the peptide cargo.

This poster demonstrates the ability of a novel Adaptable Drug Affinity Conjugate (ADAC) (a refinement of the traditional Antibody Drug Conjugate (ADC) approach) to improve peptide stability, while retaining agonistic activity and providing superior T-cell activation and expansion.

This first-in-class drug delivery strategy using ADAC technology meets demands for a flexible peptide cargo delivery strategy, ensuring in vivo T-cell priming via a CD40- targeted approach. Simultaneous immune activation and peptide presentation can ensure optimal drug efficacy and safety.