Abstract 581: bbT369, a dual-targeted and CBLB gene-edited autologous CART product, demonstrates anti-lymphoma activity in preclinical mouse models

Anti-CD19 CAR T cell therapies have improved outcomes for non-Hodgkin lymphoma (NHL) patients. However, only 30-40% of patients treated with commercially available CART cell therapies obtain long term remission, highlighting the need for more efficacious and durable therapies. Emerging clinical data suggest several failure modes for CD19 CAR T cell therapies: including loss or downregulation of CD19 antigen, loss of co-stimulation pathways on tumor cells, exhaustion of CAR-T cells, and immunosuppressive microenvironments. To overcome these hurdles, we devised the next-generation autologous CAR-T cell therapy bbT369. bbT369 is dual targeted (CD79a/CD20) CAR T cell therapy that uses an OR gate design to limit antigen escape, has split 41BB and CD28 co-stimulatory domain architecture to augment T cell activation, and contains a knock-out of the CBLB gene to enhance potency and reduce T cell exhaustion. Here we report the first results with bbT369, demonstrating anti-lymphoma activity in in vitro assays and in vivo using xenograft mouse models.

We demonstrate that CD79a and CD20 expression is B cell lineage restricted in normal human tissue and confirm that these proteins are co-expressed in diffuse large B cell samples. To target these antigens, we show a split dual-targeting CAR configuration is optimal for bbT369-directed tumor cell killing. Using an engineered megaTAL, we demonstrate high on-target activity of greater than 75% insertions and deletions (Indels) at the CBLB target site using clinical-scale manufacturing processes and low off-target activity (all off-targets less than 0.2%). In in vitro tumor co-culture assays, we show that inclusion of the CBLB gene edit in bbT369 increases Interleukin (IL)-2 production relative to an unedited anti-CD79a/CD20 CAR T cell control. Using various xenograft mouse models, we showed that bbT369 has similar or improved efficacy compared to anti-CD19 CAR drug product, including in low tumor-antigen models. In the Toledo subcutaneous xenograft model, bbT369 showed a 3-fold increase in T cell expansion compared with an unedited anti-CD79a/CD20 dual-targeting CAR T cell control. Furthermore, while a fraction of mice (3/5) receiving the unedited anti-CD79a/CD20 dual-targeting CAR T cells experienced late relapses (between 60-80 days following initial tumor clearance), all mice (n=5) receiving bbT369 were fully protected from late relapses (up to day 104 of follow-up). Collectively, the data support a first-in-human trial for bbT369 to evaluate initial safety and efficacy in NHL patients.

Citation Format: Michael Certo, Christopher Baldeviano, Sharlene Adams, Martin Asimis, Alexander Astrakhan, Andy Chavkin, Maria L. Cabral, Jimmy Chu, Marie Debrue, Devina Desai, John Evans, Pinky Htun, Amanda Iniguez, Jordan Jarjour, Carl Johnson, Harini Kantamneni, Sema Kurtulus, Michael Magee, Unja Martin, Seamus McKenney, Sara Miller, Prashant Nambiar, Vinh Khang Nguyen, Mauris Nnamani, Jen Obrigewitch, Lisa Pechilis, Molly Perkins, Christopher Petersen, Jason Pinger, Cindy Rogers, Nick Rouillard, Kendal Sanson, Emily Thompson, Collin Walter, Roslyn Yi, Sarah Voytek, Philip Gregory. bbT369, a dual-targeted and CBLB gene-edited autologous CART product, demonstrates anti-lymphoma activity in preclinical mouse models [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 581.

Optimizing a Fed-Batch High-Density Fermentation Process for Medium Chain-Length Poly(3-Hydroxyalkanoates) in Escherichia coli

Production of medium chain-length poly(3-hydroxyalkanoates) [PHA] polymers with tightly defined compositions is an important area of research to expand the application and improve the properties of these promising biobased and biodegradable materials. PHA polymers with homopolymeric or defined compositions exhibit attractive material properties such as increased flexibility and elasticity relative to poly(3-hydroxybutyrate) [PHB]; however, these polymers are difficult to biosynthesize in native PHA-producing organisms, and there is a paucity of research toward developing high-density cultivation methods while retaining compositional control. In this study, we developed and optimized a fed-batch fermentation process in a stirred tank reactor, beginning with the biosynthesis of poly(3-hydroxydecanoate) [PHD] from decanoic acid by β-oxidation deficient recombinant Escherichia coli LSBJ using glucose as a co-substrate solely for growth. Bacteria were cultured in two stages, a biomass accumulation stage (37°C, pH 7.0) with glucose as the primary carbon source and a PHA biosynthesis stage (30°C, pH 8.0) with co-feeding of glucose and a fatty acid. Through iterative optimizations of semi-defined media composition and glucose feed rate, 6.0 g of decanoic acid was converted to PHD with an 87.5% molar yield (4.54 g L-1). Stepwise increases in the amount of decanoic acid fed during the fermentation correlated with an increase in PHD, resulting in a final decanoic acid feed of 25 g converted to PHD at a yield of 89.4% (20.1 g L-1, 0.42 g L-1 h-1), at which point foaming became uncontrollable. Hexanoic acid, octanoic acid, 10-undecenoic acid, and 10-bromodecanoic acid were all individually supplemented at 20 g each and successfully polymerized with yields ranging from 66.8 to 99.0% (9.24 to 18.2 g L-1). Using this bioreactor strategy, co-fatty acid feeds of octanoic acid/decanoic acid and octanoic acid/10-azidodecanoic acid (8:2 mol ratio each) resulted in the production of their respective copolymers at nearly the same ratio and at high yield, demonstrating that these methods can be used to control PHA copolymer composition.

Anti-myeloma activity and molecular logic operation by Natural Killer cells in microfluidic droplets

Immune-targeted therapies that activate effector lymphocytes such as Natural Killer (NK) cells are currently being investigated for the treatment of Multiple myeloma (MM), the second most common form of hematological cancer. However, individual NK cells are highly heterogeneous in their cytolytic potential, making it difficult to detect, quantify and correlate the outcome of dynamic effector-target cell interactions at single cell resolution. Here, we present a microfluidic bioassay platform capable of activity-based screening of cellular and molecular immunotherapies. We identified distinct functional signatures associated with NK-MM cell interaction. The addition of immunomodulatory drug lenalidomide altered responses of NK-susceptible MM cells but not that of NK-tolerant MM cells. Antitumor cytotoxicity was significantly increased by the blockade of PD1/PDL1 axis as well as the clinically relevant cell line NK92, which were used to construct molecular logic functions (AND and NOT gates). A predictive agent-based mathematical model was developed to simulate progressive disease states and drug efficacy. The findings of the current study validate the applicability of this microfluidic cytotoxicity assay for immunotherapy screening, biocomputation and for future employment in detection of patient-specific cell response for precision medicine.

Writing Prompts Help Improve Expression of Conceptual Understanding in Chemistry

To improve the writing performance of secondary school students in chemistry assessments, a set of activities was developed. First, through document analysis of written tests, five categories of frequent mistakes in answers were identified: poor punctuation (capital letters, periods), missing key answer components (omitting concepts necessary to answer the question), incomplete reasoning (logical steps are missing), unclear use of antecedents (meanings of pronouns such as "it" are difficult to discern), and poor connectives (words like "because" are lacking or used incorrectly). After this, five strategies were formulated: focus on punctuation, repeat key question components, show complete reasoning, minimize use of references, and check use of connectives. Second, a two-part intervention study was conducted. In Part A, a written prompt (arrow symbol with the word "LANGUAGE") placed in front of context-based questions was implemented to find out if that could help students avoid making any of those mistakes. Following promising effects on the performance of 99 students, the intervention was extended with a Part B to find out if, in addition to the prompt, bonus points (for each prompt question one bonus point was awarded if the answer was formulated correctly in terms of language use) and language support (prompt card listing the five strategies, and supportive assignments) could be of extra help to students. The findings suggest that the writing performance of students can be improved by increasing students' awareness through a simple written prompt, providing language support, and awarding bonus points for properly formulated answers to chemistry test questions.

Collagenase Lot Selection and Purification for Adipose Tissue Digestion

Crude Clostridial collagenase (CCC) remains the most widely used enzyme for the digestion of tissues prior to cell isolation and culture. CCC contains numerous components in addition to specific collagenases and proteases. A chronic problem associated with CCC is significant lot variability which occurs with respect to the ability of different lots of CCC to digest tissue. We have evaluated numerous commercially available samples of CCC for their ability to digest human liposuction-derived SC fat. Digestion capacity was evaluated as the ability to release endothelial cells from fat as well as the ability of isolated cells to adhere to tissue culture plastic. A significant variation in digestion efficacy between lots of collagenase was observed. We subsequently purified CCC using a partial purification method with dialysis and centrifugation as well as a complete purification, using liquid chromatography, to remove all nonspecific proteases. While partially purified collagenase retained digestion capacity, pure collagenase exhibited reduced digestion capacity. Maximum digestion was achieved with pure collagenase when trypsin was added. The use of completely purified collagenase with trypsin is advantageous where all components in the enzyme digestion mixture must be known.

Modulation of gastrointestinal function by MuDelta, a mixed µ opioid receptor agonist/ µ opioid receptor antagonist

BACKGROUND & PURPOSE

Loperamide is a selective µ opioid receptor agonist acting locally in the gastrointestinal (GI) tract as an effective anti-diarrhoeal but can cause constipation. We tested whether modulating µ opioid receptor agonism with δ opioid receptor antagonism, by combining reference compounds or using a novel compound ('MuDelta'), could normalize GI motility without constipation.

EXPERIMENTAL APPROACH

MuDelta was characterized in vitro as a potent µ opioid receptor agonist and high-affinity δ opioid receptor antagonist. Reference compounds, MuDelta and loperamide were assessed in the following ex vivo and in vivo experiments: guinea pig intestinal smooth muscle contractility, mouse intestinal epithelial ion transport and upper GI tract transit, entire GI transit or faecal output in novel environment stressed mice, or four weeks after intracolonic mustard oil (post-inflammatory). Colonic δ opioid receptor immunoreactivity was quantified.

KEY RESULTS

δ Opioid receptor antagonism opposed µ opioid receptor agonist inhibition of intestinal contractility and motility. MuDelta reduced intestinal contractility and inhibited neurogenically-mediated secretion. Very low plasma levels of MuDelta were detected after oral administration. Stress up-regulated δ opioid receptor expression in colonic epithelial cells. In stressed mice, MuDelta normalized GI transit and faecal output to control levels over a wide dose range, whereas loperamide had a narrow dose range. MuDelta and loperamide reduced upper GI transit in the post-inflammatory model.

CONCLUSIONS AND IMPLICATIONS

MuDelta normalizes, but does not prevent, perturbed GI transit over a wide dose-range in mice. These data support the subsequent assessment of MuDelta in a clinical phase II trial in patients with diarrhoea-predominant irritable bowel syndrome.

Prokineticin-1 evokes secretory and contractile activity in rat small intestine

BACKGROUND

Prokineticins 1 and 2 (PROK1 and PROK2) are so named because they contract gastrointestinal smooth muscle, yet little else is known about their role in gastrointestinal function. Therefore, we used a combination of approaches to elucidate the mechanisms by which PROK1 alters ileal contractility and secretion in rats.

METHODS

RT-PCR and immunofluorescence were used to determine PROK and receptor (PK-R) mRNA levels and PK-R1 localization, respectively. Upper GI transit and fluid secretion were determined in vivo. Contractility and intestinal epithelial ion transport were assessed in isolated ileal segments.

KEY RESULTS

In the gastric fundus, PROK1 mRNA is highly expressed (70-fold >PROK2 mRNA) whereas the ileum has the highest mRNA expression of its receptor. PK-R1 immunoreactivity is visualized in ileal crypt cells, and in submucosal and myenteric neurons. In ileal segments, PROK1 evokes biphasic contractile responses consisting of an early, TTX-sensitive response (EC(50) = 87.8 nmol L(-1)) followed by a late, TTX-insensitive (EC(50) = 72.4 nmol L(-1)) component that is abolished in mucosa-free preparations. Oral administration of PROK1 enhances small bowel transit (111 +/- 3% of control) and fluid secretion (340 +/- 90% of control) and in muscle-stripped ileal preparations increases short-circuit current (EC(50) = 8.2 nmol L(-1)) in a TTX-insensitive manner. The PROK1-evoked Cl- secretion is reduced by piroxicam (non-selective cyclooxygenase inhibitor), and a prostaglandin EP(4) receptor antagonist (AH23848), but not a thromboxane receptor antagonist (GR32191B).

CONCLUSIONS & INFERENCES

These results demonstrate that PROK1 has oral prokinetic and secretogogue activity and that it acts on the intestinal mucosa via PK-R1 and prostaglandin receptors to mediate these effects.

Origin of endothelial cells that line expanded polytetrafluorethylene vascular grafts sodded with cells from microvascularized fat

PURPOSE

Cell transplantation onto prosthetic vascular grafts remains an attractive technique to reduce the thrombogenicity of polymeric materials. In this study we evaluated whether autologous cells isolated from falciform ligament fat and transplanted onto the lumenal surface of 4 mm expanded polytetrafluorethylene grafts were the same cells present on the surface of these grafts when they were explanted from canine carotid arteries 3 weeks after their implantation.

METHODS

The fluorescent dye PKH-26 was used to label transplanted cells to evaluate their fate after implantation of grafts as carotid artery replacements. This fluorescent dye homogeneously labeled all cells in the primary cell isolate.

RESULTS

In vitro studies indicated that dye labeling was nontoxic, as evidenced by the normal growth characteristics of fluorescently labeled cells compared with nonlabeled cells. Immunocytochemical analysis of microvascularized fat before cell isolation determined that approximately 90% of the cells stained positive for von Willebrand factor2. At the time of explant, seeded grafts exhibited a nonthrombogenic lumenal cell lining as evidenced by the lack of adherent platelets or fibrin. Cells on the lumenal surface of grafts exhibited PKH-26 fluorescence emission. In addition, these cells expressed von Willebrand factor and actively sequestered DiI-acetylated low-density lipoprotein.

CONCLUSIONS

We conclude that sodding of prosthetic grafts with autologous microvascularized fat-derived cells results in the formation of an endothelial cell lining on the lumenal flow surface. These endothelial cells are the same cells placed on the lumenal surface of the graft at the time of initial cell transplantation. Finally, a confluent monolayer forms after high-density cell sodding by the process of cell adherence and spreading, without the need for cell proliferation.

[A method of feating intermittent divergence strabismus (author's transl)]

Patching appears to have sensory and motor effects on intermittent exotropia. The sensory effects we have observed are reduction in the size of the scotoma as measured on haploscopic devices and improvement in fusional amplitudes. The motor effects has been increased control of the deviation. A series of patients was studied to document these effects, and their significance in management was discussed.