Abstract 2973: NI-3201,a PD-L1xCD28 bispecific antibody for immune checkpoint-dependent CD28 co-stimulation

CD28 agonism on T cells delivers a critical second signal alongside TCR ligation for complete T cell activation. In the tumor microenvironment (TME), signal 2 can be provided by bispecific antibodies (bsAbs) targeting CD28 and a tumor associated antigen (TAA), enabling CD28 clustering on T cells in a TAA-dependent manner. The inhibitory PD-L1/PD-1 axis is described to repress T cell activation by directly inhibiting CD28 driven costimulation, affecting mostly activated and/or exhausted T cells. Preclinical studies have shown the benefit of combining blocking anti-PD-1/-L1 antibodies and costimulatory CD28 bsAbs for the treatment of solid tumors. We reasoned that the effect of such a combination could be integrated into a single molecule, by associating a blocking anti-PD-L1 antibody arm with an agonist anti-CD28 antibody arm. To this end, a PD-L1xCD28 bsAb (NI-3201) was generated on the κλ body platform to block the PD-L1/PD-1 immune checkpoint, hence release the brake on CD28 signaling and provide signal 2 when co-ligating PD-L1+ tumor and immune cells (e.g., antigen-presenting cells). The capacity of NI-3201 to provide signal 2 to T cells following co-engagement of PD-L1 on tumor or immune cells was assessed in a variety of assays and models. Using a sensitive reporter cell bioassay, NI-3201 was shown to efficiently block the PD-L1/PD-1 axis. The pharmacological activity of NI-3201 was then assessed through in vitro assays of cancer cell lines co-cultured with human peripheral blood mononuclear cells (PBMCs). NI-3201 synergized with CD3 bsAbs to enhance activation and proliferation of both CD4 and CD8 T cells, ultimately leading to strengthened T cell-dependent cellular cytotoxicity (TDCC) against PD-L1-positive cancer cell lines. In immunocompetent huCD28-transgenic mice engrafted with huPD-L1-expressing murine colon adenocarcinoma MC38 cells, NI-3201 displayed superior single-agent activity as compared to the anti-PD-L1 antibody Atezolizumab, with tumor regression being observed in all treated mice. At study termination, most of the NI-3201-treated mice rejected MC38-huPD-L1 tumors. All surviving mice rechallenged with wild type MC38 cells rejected the tumors, thus demonstrating a durable anti-tumor immunological memory response induced by NI-3201. Finally, as the anti-PD-L1 arm of NI-3201 is cross-reactive to mouse PD-L1, it was noteworthy that NI-3201-treated huCD28-transgenic mice displayed no clinical signs of toxicity. NI-3201 has demonstrated potent activity in a plethora of assays and single agent anti-tumor in vivo activity superior to a clinically approved PD-L1 benchmark. The mechanism of action of NI-3201 and the data presented herein support the use of this molecule as a universal combination partner for CD3-bispecifics. Pre-clinical development of NI-3201 is ongoing, with pharmacokinetic and tolerability studies in non-human primates planned for early 2023.

Citation Format: Sara Majocchi, Pauline Lloveras, Coline Burnet-Merlin, Lise Nouveau, Pauline Malinge, Valery Moine, Giovanni Magistrelli, Limin Shang, Nicolas Fischer, Krzysztof Masternak, Walter Ferlin. NI-3201,a PD-L1xCD28 bispecific antibody for immune checkpoint-dependent CD28 co-stimulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2973.

Abstract 2884: Optimized CD28 bispecific antibodies for targeted activation of T cells within the tumor microenvironment

Tumor-targeted CD28 bispecific antibodies (bsAbs) are designed to co-stimulate T cells specifically within the tumor microenvironment. By bridging T cells to malignant cells expressing a selected tumor-associated antigen (TAA), CD28 bsAbs deliver the so-called signal 2 to T cells unleashing their full cytotoxic potential. Contrary to bivalent CD28 monoclonal antibody (mAb) superagonists, the activation of CD28 with monovalent CD28 bispecifics requires the binding of a TAA expressed by the cancer cells to induce CD28 clustering. Preclinical studies have shown the benefit of adding costimulatory CD28 bsAbs for the treatment of solid tumors, boosting the efficacy of bispecific T cell engagers (CD3 bsAbs) or PD-(L)1 checkpoint inhibitors.

Using our proprietary fully human κλ body antibody platform, which relies on a common heavy chain and on two distinct light chains driving specificity and affinity (i.e., one kappa and one lambda), we have identified a panel of agonist anti-CD28 kappa arms. Using our existing lambda anti-TAA arms (e.g., targeting CD19, MSLN, HER2, EGFR), an array of TAA-CD28 κλ bodies targeting different tumors were generated. The capacity of these CD28 κλ bodies to provide signal 2 to T cells was assessed both in vitro and in vivo in combination with CD3 bsAbs. In the presence of cancer cells and corresponding TAA-CD3 bsAbs, the CD28 κλ bodies enabled the activation of primary human CD4 and CD8 T cells, leading to T cell proliferation and secretion of cytokines such as IL-2 and IFNγ, and granzyme B. Importantly, when used alone or in combination with an untargeted CD3 bsAb (that is, in the absence of signal 1), CD28 κλ bodies showed no sign of T cell activation, potentially limiting peripheral toxicity. The resulting change in the T cell activation status led to a potent in vitro T cell-dependent cellular cytotoxicity (TDCC) against TAA-expressing cancer cell lines. CD28 κλ bodies targeting gastrointestinal tumors were tested in combination with CD3 bsAbs in xenogeneic tumor models and synergistically improved the antitumoral activity of T cell engagers, leading to an enhanced tumor control. Thus, via the identification of optimal agonist anti CD28 arms, CD28 bsAbs targeting multiple TAAs were designed for tumor-specific activation of the immune system. The resulting TAA-CD28 κλ bodies can enhance the antitumor response induced by CD3-retargeting bsAbs via the induction of T cell proliferation and activation, increased cytokine secretion and boosted anti-tumoral cytotoxicity. Other anti-TAA arms are being explored, to expand the panel of TAAs that could be easily paired with our anti-CD28 platform arms.

Citation Format: Sara Majocchi, Pauline Lloveras, Coline Burnet-Merlin, Lise Nouveau, Nicolas Pleche, Pauline Malinge, Claudia Batista, Christelle Daviet, Maud Charreton, Guillemette Pontini, Franck Gueneau, Valery Moine, Giovanni Magistrelli, Limin Shang, Walter Ferlin, Krzysztof Masternak. Optimized CD28 bispecific antibodies for targeted activation of T cells within the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2884.

Abstract 3428: NI-2901, a CD47xPD-L1 bispecific antibody for dual immune checkpoint blockade with fine-tuned affinity to reduce erythrocyte binding and improve biodistribution

Blocking the CD47/SIRPα checkpoint has recently emerged as an effective approach to mobilize the myeloid cell compartment and to improve antitumor responses in the clinic. Preclinical models have demonstrated the synergistic benefit of combined CD47/SIRPα and PD-1/PD-L1 blockade. Combinations of monoclonal antibodies (mAbs) targeting these two checkpoint pathways are being explored in the clinic. CD47xPD-L1 bispecific antibodies (bsAbs) stand as an attractive alternative to mAb combinations, even more so as they provide a potential solution to improve the pharmacokinetic profile and safety issues faced by CD47 targeted-mAbs and SIRPα-Fc fusion proteins. CD47xPD-L1 bsAbs are expected to preferentially inhibit CD47 on PD-L1 expressing cells, displaying improved safety and pharmacokinetics, but also superior tumor microenvironment targeting capabilities. With the objective of finding the optimal CD47xPD-L1 bsAb, an array of bispecific antibodies (bsAbs) was generated associating a high affinity PD-L1 arm to CD47 arms with varying affinities. The CD47xPD-L1 bsAbs of human IgG4 isotype were generated using our fully human κλ body antibody platform. The candidate molecules were screened for binding and receptor-blocking activity and tested for their capacity to enhance T-cell activation and phagocytosis of tumor cells in the presence of anti-HER-2 mAb, trastuzumab. Selected bsAbs were also evaluated in a xenograft mouse model. The CD47xPD-L1 bsAbs demonstrated an effective blockade of the PD-1/PD-L1 interaction, being able to induce T-cell activation in vitro similar to the anti-PD-L1 clinical benchmark, atezolizumab. Consistent with their CD47 affinities, the bsAbs showed varying levels of CD47 blockade on PD-L1-negative cells and a low binding capacity to red blood cells. Nonetheless, trastuzumab-mediated phagocytosis of tumor cells expressing low levels of PD-L1 could be significantly enhanced by these bsAbs, confirming the PD-L1-independent activity of the CD47 blocking arms. The latter findings were corroborated in vivo using PD-L1-negative Raji cells in a xenograft mouse model. Selected bsAbs will be now tested for tolerability and pharmacokinetic profiles in human-CD47/human-SIRPα transgenic mice. Lead candidate(s) will be evaluated further for PK and safety attributes in non-human primates in early Q1, 2022.

Citation Format: Xavier Chauchet, Sébastien Calloud, Margaux Legrand, Laura Cons, Laurence Chatel, Pauline Lloveras, Coline Burnet-Merlin, Louis Hellequin, Nicolas Bosson, Pauline Malinge, Nicolas Pleche, Jérémie Bourguignon, Guillemette Pontini, Christophe Guillamo, Ulla Ravn, Valéry Moine, Bruno Daubeuf, Yves Poitevin, Giovanni Magistrelli, Limin Shang, Walter Ferlin, Krzysztof Masternak. NI-2901, a CD47xPD-L1 bispecific antibody for dual immune checkpoint blockade with fine-tuned affinity to reduce erythrocyte binding and improve biodistribution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3428.

Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol

There is currently great interest in replacing the harmful volatile hydrofluorocarbon fluids used in refrigeration and air-conditioning with solid materials that display magnetocaloric, electrocaloric or mechanocaloric effects. However, the field-driven thermal changes in all of these caloric materials fall short with respect to their fluid counterparts. Here we show that plastic crystals of neopentylglycol (CH₃)₂C(CH₂OH)₂ display extremely large pressure-driven thermal changes near room temperature due to molecular reconfiguration, that these changes outperform those observed in any type of caloric material, and that these changes are comparable with those exploited commercially in hydrofluorocarbons. Our discovery of colossal barocaloric effects in a plastic crystal should bring barocaloric materials to the forefront of research and development in order to achieve safe environmentally friendly cooling without compromising performance.

There is great interest, in refrigeration technology, in replacing harmful volatile hydrofluorocarbons with solid materials. Here the authors show that commercially available plastic crystal neopentylglycol displays colossal and reversible barocaloric effects comparable with those exploited in hydrofluorocarbons, which make it suitable for application.

Criticality in the slowed-down boiling crisis at zero gravity

Boiling crisis is a transition between nucleate and film boiling. It occurs at a threshold value of the heat flux from the heater called CHF (critical heat flux). Usually, boiling crisis studies are hindered by the high CHF and short transition duration (below 1 ms). Here we report on experiments in hydrogen near its liquid-vapor critical point, in which the CHF is low and the dynamics slow enough to be resolved. As under such conditions the surface tension is very small, the experiments are carried out in the reduced gravity to preserve the conventional bubble geometry. Weightlessness is created artificially in two-phase hydrogen by compensating gravity with magnetic forces. We were able to reveal the fractal structure of the contour of the percolating cluster of the dry areas at the heater that precedes the boiling crisis. We provide a direct statistical analysis of dry spot areas that confirms the boiling crisis at zero gravity as a scale-free phenomenon. It was observed that, in agreement with theoretical predictions, saturated boiling CHF tends to zero (within the precision of our thermal control system) in zero gravity, which suggests that the boiling crisis may be observed at any heat flux provided the experiment lasts long enough.

Boiling crisis as a critical phenomenon

We present the first experimental study of intermittency and avalanche distribution during a boiling crisis. To understand the emergence of power law statistics we propose a simple spin model capturing the measured critical exponent. The model suggests that behind the critical heat flux is a percolation phenomenon involving drying-rewetting competition close to the hot surface.

[Antibody-coated bacteria and quantitative culture in sputum samples from patients with bronchiectasis]

The results of the quantitative culture of sputum samples from patients with bronchiectasis were compared with those obtained in the same samples with the detection of antibody-coated bacteria (ACB), in the acute phase of the disease (group I), after antibiotic therapy (group II), and in the phase of clinical stability (group III). In quantitative cultures at least one potentially pathogen species was isolated, at a concentration of greater than or equal to 10(6) colony forming units/ml in the 7 sputum samples from group I, in 4 of the 5 samples from group II, and in 10 of the 11 samples from group III. The immunofluorescence technique detected ACB in all samples from group I and group II, and in 10 of the 11 from group III. The sample from group III in which ACB were not detected was the same in which potentially pathogen organisms were not detected by culture.