FOXO1 is a master regulator of memory programming in CAR T cells

A major limitation of chimeric antigen receptor (CAR) T cell therapies is the poor persistence of these cells in vivo1. The expression of memory-associated genes in CAR T cells is linked to their long-term persistence in patients and clinical efficacy2-6, suggesting that memory programs may underpin durable CAR T cell function. Here we show that the transcription factor FOXO1 is responsible for promoting memory and restraining exhaustion in human CAR T cells. Pharmacological inhibition or gene editing of endogenous FOXO1 diminished the expression of memory-associated genes, promoted an exhaustion-like phenotype and impaired the antitumour activity of CAR T cells. Overexpression of FOXO1 induced a gene-expression program consistent with T cell memory and increased chromatin accessibility at FOXO1-binding motifs. CAR T cells that overexpressed FOXO1 retained their function, memory potential and metabolic fitness in settings of chronic stimulation, and exhibited enhanced persistence and tumour control in vivo. By contrast, overexpression of TCF1 (encoded by TCF7) did not enforce canonical memory programs or enhance the potency of CAR T cells. Notably, FOXO1 activity correlated with positive clinical outcomes of patients treated with CAR T cells or tumour-infiltrating lymphocytes, underscoring the clinical relevance of FOXO1 in cancer immunotherapy. Our results show that overexpressing FOXO1 can increase the antitumour activity of human CAR T cells, and highlight memory reprogramming as a broadly applicable approach for optimizing therapeutic T cell states.

FOXO1 is a master regulator of CAR T memory programming

Poor CAR T persistence limits CAR T cell therapies for B cell malignancies and solid tumors1,2. The expression of memory-associated genes such as TCF7 (protein name TCF1) is linked to response and long-term persistence in patients3-7, thereby implicating memory programs in therapeutic efficacy. Here, we demonstrate that the pioneer transcription factor, FOXO1, is responsible for promoting memory programs and restraining exhaustion in human CAR T cells. Pharmacologic inhibition or gene editing of endogenous FOXO1 in human CAR T cells diminished the expression of memory-associated genes, promoted an exhaustion-like phenotype, and impaired antitumor activity in vitro and in vivo. FOXO1 overexpression induced a gene expression program consistent with T cell memory and increased chromatin accessibility at FOXO1 binding motifs. FOXO1-overexpressing cells retained function, memory potential, and metabolic fitness during settings of chronic stimulation and exhibited enhanced persistence and antitumor activity in vivo. In contrast, TCF1 overexpression failed to enforce canonical memory programs or enhance CAR T cell potency. Importantly, endogenous FOXO1 activity correlated with CAR T and TIL responses in patients, underscoring its clinical relevance in cancer immunotherapy. Our results demonstrate that memory reprogramming through FOXO1 can enhance the persistence and potency of human CAR T cells and highlights the utility of pioneer factors, which bind condensed chromatin and induce local epigenetic remodeling, for optimizing therapeutic T cell states.

Costimulatory domains direct distinct fates of CAR-driven T-cell dysfunction

T cells engineered to express chimeric antigen receptors (CARs) targeting CD19 have demonstrated impressive activity against relapsed or refractory B-cell cancers yet fail to induce durable remissions for nearly half of all patients treated. Enhancing the efficacy of this therapy requires detailed understanding of the molecular circuitry that restrains CAR-driven antitumor T-cell function. We developed and validated an in vitro model that drives T-cell dysfunction through chronic CAR activation and interrogated how CAR costimulatory domains, central components of CAR structure and function, contribute to T-cell failure. We found that chronic activation of CD28-based CARs results in activation of classical T-cell exhaustion programs and development of dysfunctional cells that bear the hallmarks of exhaustion. In contrast, 41BB-based CARs activate a divergent molecular program and direct differentiation of T cells into a novel cell state. Interrogation using CAR T cells from a patient with progressive lymphoma confirmed the activation of this novel program in a failing clinical product. Furthermore, we demonstrate that 41BB-dependent activation of the transcription factor FOXO3 is directly responsible for impairing CAR T-cell function. These findings identify that costimulatory domains are critical regulators of CAR-driven T-cell failure and that targeted interventions are required to overcome costimulation-dependent dysfunctional programs.

Cancer Demographics and Time-to-Care in Belize

BACKGROUND

Belize is a middle-income Caribbean country with poorly described cancer epidemiology and no comprehensive cancer care capacity. In 2018, GO, Inc., a US-based NGO, partnered with the Ministry of Health and the national hospital in Belize City to create the first public oncology clinic in the country. Here, we report demographics from the clinic and describe time intervals to care milestones to allow for public health targeting of gaps.

PATIENTS AND METHODS

Using paper charts and a mobile health platform, we performed a retrospective chart review at the Karl Heusner Memorial Hospital (KHMH) clinic from 2018 to 2022.

RESULTS

During this time period, 465 patients with cancer presented to the clinic. Breast cancer (28%) and cervical cancer (12%) were most common. Most patients (68%) presented with stage 3 or 4 disease and were uninsured (78%) and unemployed (79%). Only 21% of patients ever started curative intent treatment. Median time from patient-reported symptoms to a biopsy or treatment was 130 and 189 days. For the most common cancer, breast, similar times were seen at 140 and 178 days. Time intervals at the clinic: <30 days from initial visit to biopsy (if not previously performed) and <30 days to starting chemotherapy.

CONCLUSION

This study reports the first clinic-based cancer statistics for Belize. Many patients have months between symptom onset and treatment. In this setting, the clinic has built infrastructure allowing for minimal delays in care despite an underserved population. This further affirms the need for infrastructure investment and early detection programs to improve outcomes in Belize.

Costimulatory domains direct distinct fates of CAR-driven T cell dysfunction

Chimeric antigen receptor (CAR) engineered T cells often fail to enact effector functions after infusion into patients. Understanding the biological pathways that lead CAR T cells to failure is of critical importance in the design of more effective therapies. We developed and validated an in vitro model that drives T cell dysfunction through chronic CAR activation and interrogated how CAR costimulatory domains contribute to T cell failure. We found that dysfunctional CD28-based CARs targeting CD19 bear hallmarks of classical T cell exhaustion while dysfunctional 41BB-based CARs are phenotypically, transcriptionally and epigenetically distinct. We confirmed activation of this unique transcriptional program in CAR T cells that failed to control clinical disease. Further, we demonstrate that 41BB-dependent activation of the transcription factor FOXO3 is a significant contributor to this dysfunction and disruption of FOXO3 improves CAR T cell function. These findings identify that chronic activation of 41BB leads to novel state of T cell dysfunction that can be alleviated by genetic modification of FOXO3.

Summary

Chronic stimulation of CARs containing the 41BB costimulatory domain leads to a novel state of T cell dysfunction that is distinct from T cell exhaustion.

Antigen glycosylation regulates efficacy of CAR T cells targeting CD19

While chimeric antigen receptor (CAR) T cells targeting CD19 can cure a subset of patients with B cell malignancies, most patients treated will not achieve durable remission. Identification of the mechanisms leading to failure is essential to broadening the efficacy of this promising platform. Several studies have demonstrated that disruption of CD19 genes and transcripts can lead to disease relapse after initial response; however, few other tumor-intrinsic drivers of CAR T cell failure have been reported. Here we identify expression of the Golgi-resident intramembrane protease Signal peptide peptidase-like 3 (SPPL3) in malignant B cells as a potent regulator of resistance to CAR therapy. Loss of SPPL3 results in hyperglycosylation of CD19, an alteration that directly inhibits CAR T cell effector function and suppresses anti-tumor cytotoxicity. Alternatively, over-expression of SPPL3 drives loss of CD19 protein, also enabling resistance. In this pre-clinical model these findings identify post-translational modification of CD19 as a mechanism of antigen escape from CAR T cell therapy.

Updated demographics at the only public oncology clinic in Belize

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Background: Belize is a middle-income Caribbean country without comprehensive cancer care capacity and poorly described cancer epidemiology. In 2020, we reported some of the first cancer demographics from the country. This was made possible by a capacity building partnership with the only public oncology clinic in the country at Karl Heusner Memorial Hospital (KHMH). Here we provide an update on demographic trends at this clinic. Methods: We performed a retrospective chart review of all available patient data at the KHMH clinic from December 2020 to December 2021. This was compared to data from the clinic’s founding in 2018 through its first 12 months. Results: From December 2020 through December 2021, the clinic saw 332 patients, an increase of 141% from the 236 patients seen over the first 12-month period of the clinic. In 2021, 250 (75%) patients had a confirmed pathologic diagnosis of cancer, with 78 (23%) remaining under clinical suspicion. This is in comparison to 63% of patients with a pathologic diagnosis in 2018. H&E staining alone remained the only publicly available pathologic service. Patients were predominantly female (67%) with a median age of 54 (Range: 2-95). The most common histologies (n = 332) were breast (29%), cervical (11%), colorectal (8%), prostate (4%), gastric (4%), and lung (3%). Of patients with histologically confirmed cancer, 221 (66%) were able to be fully staged. Patients predominantly presented with later stage disease (25% Stage III, 34% Stage IV). At the end of 2021, out of all patients tracked longitudinally over the year (n = 332), 24% remained in need of full diagnostic assessment, 34% were on curative treatment (predominantly cytotoxic chemotherapy), 22% were under surveillance, and 18% were receiving palliative chemotherapy or best supportive care due to advanced disease. This is in comparison to 2018, when there was no capacity to administer chemotherapy at KHMH and patients were referred to either private clinics or out of the country. Conclusions: The burden of cancer in Belize is significant and diverse. Compared to 2018, in 2021, the number of patients seen at KHMH increased 141%, as did the percentage of patients with histologically confirmed cancer (120% increase). Chemotherapy treatment was made possible through procurement of a chemotherapeutic stock at KHMH due to key partnerships with the Belizean government, hospital administration, and crucially, the only medical oncologist in the nation. This has led to chemotherapy being available at a public clinic in the country for the first time. Despite this progress, patients continue to present at late stages and many cannot access cancer care due to limited resources, cost, and low public awareness. This further affirms the need for infrastructure investment and early detection programs to improve cancer outcomes in Belize.

Breast cancer characteristics and time to chemotherapy initiation in Belize

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Background: Breast cancer is the most common cancer in low and middle-income countries. Belize, a middle-income country in the Caribbean with significant inequality, lacks a national screening program and has limited treatment capacity. There are no studies describing breast cancer characteristics in Belize in the available literature. We collected data from the sole public oncology clinic in the country, established in 2018 at Karl Heusner Memorial Hospital (KHMH), to describe the characteristics of breast cancer patients and establish baseline measurements of time to chemotherapy initiation for the curative intent treatment population; the aim being to identify potential areas for quality improvement. Methods: We performed a retrospective chart review of available patient data from December 2020 to December 2021. We examined the time from a patient’s initial visit at KHMH until chemotherapy initiation (TCI) in the neoadjuvant setting with patients stratified by stage. Significant outliers (predominantly patients with misclassified data or those with private access to physicians and therapeutics) were excluded. Results: The clinic provided care for 80 patients with biopsy-proven breast cancer between December 2020 to December 2021. Patients were 97% female with a median age of 55 (Range: 34-81). For stageable patients (n=75), 33% presented with clinically localized disease, 49% with locally advanced, and 17% with recurrent or metastatic disease. Of the 51 patients on chemotherapy, 57% were receiving preoperative treatment, 31% were on adjuvant therapy, and 12% on palliative therapy. Patients not on therapy (n=29) at KHMH were either in surveillance, referred to a private cancer center, or deceased. Neoadjuvant TCI was calculated for 21 patients after the removal of outliers (n=5). The majority of these patients arrived at their initial clinic visit with a biopsy-proven diagnosis. Mean TCI for early stage disease was 49 days (n=7, 95% CI [9, 89]) and locally advanced disease was 36 days (n=14, 95% CI [12, 61]). Aggregate mean TCI was 40 days (n=21, 95% CI [19, 62]). Conclusions: In Belize, breast cancer affects younger women and patients present with later stages of disease than in high-income countries; however, time to chemotherapy initiation in a small sample of neoadjuvant patients at the Belizean clinic was comparable. Given the inherent limitations of small samples of data, additional investigation is needed to support these findings, as well as to delineate patient barriers to access and potential for improvements in clinic follow-up. Nevertheless, indications of a robust TCI call for further characterization of this newly established cancer clinic and its practices.

Anti-GD2 synergizes with CD47 blockade to mediate tumor eradication

The disialoganglioside GD2 is overexpressed on several solid tumors, and monoclonal antibodies targeting GD2 have substantially improved outcomes for children with high-risk neuroblastoma. However, approximately 40% of patients with neuroblastoma still relapse, and anti-GD2 has not mediated significant clinical activity in any other GD2+ malignancy. Macrophages are important mediators of anti-tumor immunity, but tumors resist macrophage phagocytosis through expression of the checkpoint molecule CD47, a so-called 'Don't eat me' signal. In this study, we establish potent synergy for the combination of anti-GD2 and anti-CD47 in syngeneic and xenograft mouse models of neuroblastoma, where the combination eradicates tumors, as well as osteosarcoma and small-cell lung cancer, where the combination significantly reduces tumor burden and extends survival. This synergy is driven by two GD2-specific factors that reorient the balance of macrophage activity. Ligation of GD2 on tumor cells (a) causes upregulation of surface calreticulin, a pro-phagocytic 'Eat me' signal that primes cells for removal and (b) interrupts the interaction of GD2 with its newly identified ligand, the inhibitory immunoreceptor Siglec-7. This work credentials the combination of anti-GD2 and anti-CD47 for clinical translation and suggests that CD47 blockade will be most efficacious in combination with monoclonal antibodies that alter additional pro- and anti-phagocytic signals within the tumor microenvironment.

Transient rest restores functionality in exhausted CAR-T cells through epigenetic remodeling

T cell exhaustion limits immune responses against cancer and is a major cause of resistance to chimeric antigen receptor (CAR)-T cell therapeutics. Using murine xenograft models and an in vitro model wherein tonic CAR signaling induces hallmark features of exhaustion, we tested the effect of transient cessation of receptor signaling, or rest, on the development and maintenance of exhaustion. Induction of rest through enforced down-regulation of the CAR protein using a drug-regulatable system or treatment with the multikinase inhibitor dasatinib resulted in the acquisition of a memory-like phenotype, global transcriptional and epigenetic reprogramming, and restored antitumor functionality in exhausted CAR-T cells. This work demonstrates that rest can enhance CAR-T cell efficacy by preventing or reversing exhaustion, and it challenges the notion that exhaustion is an epigenetically fixed state.

c-Jun overexpression in CAR T cells induces exhaustion resistance

Chimeric antigen receptor (CAR) T cells mediate anti-tumour effects in a small subset of patients with cancer^1-3, but dysfunction due to T cell exhaustion is an important barrier to progress^4-6. To investigate the biology of exhaustion in human T cells expressing CAR receptors, we used a model system with a tonically signaling CAR, which induces hallmark features of exhaustion⁶. Exhaustion was associated with a profound defect in the production of IL-2, along with increased chromatin accessibility of AP-1 transcription factor motifs and overexpression of the bZIP and IRF transcription factors that have been implicated in mediating dysfunction in exhausted T cells^7-10. Here we show that CAR T cells engineered to overexpress the canonical AP-1 factor c-Jun have enhanced expansion potential, increased functional capacity, diminished terminal differentiation and improved anti-tumour potency in five different mouse tumour models in vivo. We conclude that a functional deficiency in c-Jun mediates dysfunction in exhausted human T cells, and that engineering CAR T cells to overexpress c-Jun renders them resistant to exhaustion, thereby addressing a major barrier to progress for this emerging class of therapeutic agents.

The relationship between children's physical activity and family income in rural settings: A cross-sectional study

Objective

To examine potential differences in children's physical activity and parent support of their children's physical activity based on family income within the rural setting.

Methods

A cross-sectional survey of 566 parents of children (5–15 years-old; mean = 7.7 years; standard deviation = 2.4) living in rural West Virginia from 2010 to 2011 was conducted. Children were recruited and had participated in a school-based health screening program.

Results

Overall, parents from a rural setting reported that their children engaged in an average of five days of physical activity for at least 60 min. Upon closer examination, children from lower-income families engaged in more physical activity, on average, than children from higher income families per parent report (mean = 6.6 days, confidence interval 95% = 4.9–6.0 vs. middle-income mean = 5.0, confidence interval 95% = 4.4–5.3 and highest-income mean = 4.5, confidence interval 95% = 4.1–4.7; p = .01). Rural parents supported their children's physical activity in numerous ways. Parents with the lowest incomes were more likely than parents from higher income families to encourage their children to be active and use their immediate environment for play and to be directly involved in physical activity with their children. More affluent parents were more likely to transport their children to other activity opportunities than parents from the lower income brackets.

Conclusions

Lower income families may utilize their immediate environment and encourage activity among their children whereas more affluent families focus on organized opportunity more often than lower income families. These findings emphasize the need to conceptualize the role family income plays in physical activity patterns and the potential benefit it provides to some families.

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Rural children engage in at least 60 min of physical activity per parents.

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Children from lower-income families engage in more weekly physical activity.

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Lower income parents are more likely to support their children's physical activity.