Hypoparathyroidism (HP) is a condition of parathyroid hormone (PTH) deficiency leading to abnormal calcium and phosphate metabolism. The mainstay of therapy consists of vitamin D and calcium supplements, as well as adjunct Natpara (PTH(1‐84)). However, neither therapy optimally controls urinary calcium (uCa) or significantly reduces the incidence of hypercalcemia and hypocalcemia. TransCon PTH, a sustained‐release prodrug of PTH(1‐34) in development for the treatment of HP, was designed to overcome these limitations. To determine the pharmacokinetics and pharmacodynamics of TransCon PTH, single and repeat s.c. dose studies were performed in rats and monkeys. TransCon PTH demonstrated a half‐life of 28 and 34 hours in rats and monkeys, respectively. After repeated dosing, an infusion‐like profile of the released PTH, characterized by low peak‐to‐trough levels, was obtained in both species. In intact rats and monkeys, daily subcutaneous administration of TransCon PTH was associated with increases in serum calcium (sCa) levels and decreases in serum phosphate levels (sP). In monkeys, at a single dose of TransCon PTH that increased sCa levels within the normal range, a concurrent decrease in uCa excretion was observed. In 4‐week repeat‐dose studies in intact rats and monkeys, uCa excretion was comparable to controls across all dose levels despite increases in sCa levels. Further, in a rat model of HP, TransCon PTH normalized sCa and sP levels 24 hours per day. This was in contrast to only transient trends toward normalization of sCa and sP levels with an up to 6‐fold higher molar dose of PTH(1‐84). After repeated dosing to HP rats, uCa excretion transiently increased, corresponding to increases in sCa above normal range, but at the end of the treatment period, uCa excretion was generally comparable to sham controls. TransCon PTH was well tolerated and the observed pharmacokinetics and pharmacodynamics were in line with the expected action of physiological replacement of PTH. © 2019 American Society for Bone and Mineral Research.

The fundamental challenge of developing a long-acting growth hormone (LAGH) is to create a more convenient growth hormone (GH) dosing profile while retaining the excellent safety, efficacy and tolerability of daily GH. With GH receptors on virtually all cells, replacement therapy should achieve the same tissue distribution and effects of daily (and endogenous) GH while maintaining levels of GH and resulting IGF-1 within the physiologic range. To date, only two LAGHs have gained the approval of either the Food and Drug Administration (FDA) or the European Medicines Agency (EMA); both released unmodified GH, thus presumably replicating distribution and pharmacological actions of daily GH. Other technologies have been applied to create LAGHs, including modifying GH (for example, protein enlargement or albumin binding) such that the resulting analogues possess a longer half-life. Based on these approaches, nearly 20 LAGHs have reached various stages of clinical development. Although most have failed, lessons learned have guided the development of a novel LAGH. TransCon GH is a LAGH prodrug in which GH is transiently bound to an inert methoxy polyethylene glycol (mPEG) carrier. It was designed to achieve the same safety, efficacy and tolerability as daily GH but with more convenient weekly dosing. In phase 2 trials of children and adults with growth hormone deficiency (GHD), similar safety, efficacy and tolerability to daily GH was shown as well as GH and IGF-1 levels within the physiologic range. These promising results support further development of TransCon GH.

BackgroundRecombinant interleukin-2 (IL-2, aldesleukin) is an approved cancer immunotherapy but causes severe toxicities including cytokine storm and vascular leak syndrome (VLS). IL-2 promotes antitumor function of IL-2Rβ/γ+ natural killer (NK) cells and CD8+, CD4+ and gamma delta (γδ) T cells. However, IL-2 also potently activates immunosuppressive IL-2Rα+ regulatory T cells (Tregs) and IL-2Rα+ eosinophils and endothelial cells, which may promote VLS. Aldesleukin is rapidly cleared requiring frequent dosing, resulting in high Cmax likely potentiating toxicity. Thus, IL-2 cancer immunotherapy has two critical drawbacks: potent activation of undesired IL-2Rα+ cells and suboptimal pharmacokinetics with high Cmax and short half-life.MethodsTransCon IL-2 β/γ was designed to optimally address these drawbacks. To abolish IL-2Rα binding yet retain strong IL-2Rβ/γ activity, IL-2 β/γ was created by permanently attaching a small methoxy polyethylene glycol (mPEG) moiety in the IL-2Rα binding site. To improve pharmacokinetics, IL-2 β/γ was transiently attached to a 40 kDa mPEG carrier via a TransCon (transient conjugation) linker creating a prodrug, TransCon IL-2 β/γ, with sustained release of IL-2 β/γ. IL-2 β/γ was characterized in binding and primary cell assays while TransCon IL-2 β/γ was studied in tumor-bearing mice and cynomolgus monkeys.ResultsIL-2 β/γ demonstrated selective and potent human IL-2Rβ/γ binding and activation without IL-2Rα interactions. TransCon IL-2 β/γ showed slow-release pharmacokinetics with a low Cmax and a long (>30 hours) effective half-life for IL-2 β/γ in monkeys. In mouse tumor models, TransCon IL-2 β/γ promoted CD8+ T cell and NK cell activation and antitumor activity. In monkeys, TransCon IL-2 β/γ induced robust activation and expansion of CD8+ T cells, NK cells and γδ T cells, relative to CD4+ T cells, Tregs and eosinophils, with no evidence of cytokine storm or VLS. Similarly, IL-2 β/γ enhanced proliferation and cytotoxicity of primary human CD8+ T cells, NK cells and γδ T cells.SummaryTransCon IL-2 β/γ is a novel long-acting prodrug with sustained release of an IL-2Rβ/γ-selective IL-2. It has remarkable and durable pharmacodynamic effects in monkeys and potential for improved clinical efficacy and tolerability compared with aldesleukin. TransCon IL-2 β/γ is currently being evaluated in a Phase 1/2 clinical trial (NCT05081609).

Background Intratumoral (IT) delivery of toll-like receptor (TLR) agonists has shown encouraging anti-tumor benefit in preclinical and early clinical studies. However, IT delivery of TLR agonists may lead to rapid effusion from the tumor microenvironment (TME), potentially limiting the duration of local inflammation and increasing the risk of systemic adverse events. Methods To address these limitations, TransCon™ TLR7/8 Agonist—an investigational sustained-release prodrug of resiquimod that uses a TransCon linker and hydrogel technology to achieve sustained and predictable IT release of resiquimod—was developed. TransCon TLR7/8 Agonist was characterized for resiquimod release in vitro and in vivo, in mice and rats, and was assessed for anti-tumor efficacy and pharmacodynamic activity in mice. Results Following a single IT dose, TransCon TLR7/8 Agonist mediated potent tumor growth inhibition which was associated with sustained resiquimod release over several weeks with minimal induction of systemic cytokines. TransCon TLR7/8 Agonist monotherapy promoted activation of antigen-presenting cells in the TME and tumor-draining lymph nodes, with evidence of activation and expansion of CD8+ T cells in the tumor-draining lymph node and TME. Combination of TransCon TLR7/8 Agonist with systemic immunotherapy further promoted anti-tumor activity in TransCon TLR7/8 Agonist-treated tumors. In a bilateral tumor setting, combination of TransCon TLR7/8 Agonist with systemic IL-2 potentiated tumor growth inhibition in both injected and non-injected tumors and conferred protection against tumor rechallenge following complete regressions. Conclusions Our findings show that a single dose of TransCon TLR7/8 Agonist can mediate sustained local release of resiquimod in the TME and promote potent anti-tumor effects as monotherapy and in combination with systemic immunotherapy, supporting TransCon TLR7/8 Agonist as a novel intratumoral TLR agonist for cancer therapy. A clinical trial to evaluate the safety and efficacy of TransCon TLR7/8 Agonist, as monotherapy and in combination with pembrolizumab, in cancer patients is currently ongoing (transcendIT-101; NCT04799054).

Background: Recombinant Interleukin-2 (IL-2, aldesleukin) is an approved immunotherapy for metastatic melanoma and renal cell carcinoma. However, treatment with IL-2 can induce severe side effects, such as vascular leak syndrome (VLS) and eosinophilic infiltration of cardiac and pulmonary tissues. IL-2 promotes the survival, proliferation and anti-tumor functions of CD8+ cytotoxic T cells, CD4+ effector T cells and natural killer cells, which mostly express the dimeric IL-2Rβγ receptor with low IL-2Rα levels. However, IL-2 also potently activates IL-2Rα+ immunosuppressive regulatory T cells as well as IL-2Rα+ eosinophils, type 2 innate lymphoid cells and endothelial cells, which may promote VLS. Aldesleukin is rapidly cleared with elimination T1/2 of 85 minutes requiring thrice daily dosing and resulting in large fluctuations in serum exposure, likely contributing to its toxicity. Thus, IL-2 has two critical drawbacks for cancer immunotherapy: 1) potent activation of undesired cells types expressing IL-2Rα and 2) high Cmax with rapid clearance. Methods: We developed TransCon (transient conjugation) IL-2 β/γ, a novel sustained release prodrug of a receptor-biased IL-2 (IL-2 β/γ) to optimally address each of these drawbacks. First, to block IL-2Rα binding yet retain IL-2Rβγ activity, we created IL2 β/γ by permanently attaching a small PEG moiety to an engineered cysteine placed at the IL-2Rα binding site. Second, to improve PK properties, we attached the receptor-biased IL-2 β/γ to a TransCon PEG carrier via a TransCon linker, shielding bioactivity and creating a prodrug. Under physiological conditions, TransCon IL-2 β/γ was designed for sustained release of the bioactive IL-2 β/γ from the PEG carrier, aiming for a much lower Cmax and longer effective half-life of released IL-2 β/γ compared to aldesleukin. Results: In binding and cell-based functional assays, free IL-2 β/γ demonstrated desirable IL-2 receptor selectivity maintaining IL-2Rβγ potency while losing IL2Rα potency. In vitro, TransCon IL-2 β/γ showed expected slow-release kinetics, supporting a half-life in humans of 2-3 days. In mouse tumor models, TransCon IL2 β/γ promoted CD8 and NK cell proliferation and activation. In cynomolgus monkeys, a single dose of TransCon IL-2 β/γ was well tolerated and induced a more robust CD8+ T cell and NK cell expansion relative to CD4+ T cells or eosinophils as compared to daily aldesleukin treatment. Consistent with these observations, TransCon IL-2 β/γ induced lower levels of systemic inflammatory cytokines and endothelial activity biomarkers when compared to aldesleukin. Summary: The data presented here provide evidence that TransCon IL-2 β/γ may promote anti-tumor immune effector function with improved tolerability. TransCon IL-2 β/γ was designed as a novel long-acting, receptor-biased IL-2 prodrug that has the potential to overcome the challenges of existing IL-2 treatments. Citation Format: David Brian Rosen, Burkhardt Laufer, Thomas Knappe, Meike Schnabel, Diana Begaliew, Joachim Zettler, Mathias Krusch, Ana Bernhard, Stefan Heinig, Valentino Konjik, Thomas Wegge, Vibeke Breinholt, Mohammad Tabrizi, Kennett Sprogoe, Juha Punnonen. TransConTM IL-2 β/γ: a novel long-acting prodrug of receptor-biased IL-2 designed for improved pharmocokinetics and optimal activation of T cells for the treatment of cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4507.