Tuning the potency and selectivity of ImmTAC molecules by affinity modulation.

T-cell-engaging bispecifics have great clinical potential for the treatment of cancer and infectious diseases. The binding affinity and kinetics of a bispecific molecule for both target and T-cell CD3 have substantial effects on potency and specificity, but the rules governing these relationships are not fully understood. Using immune mobilizing monoclonal TCRs against cancer (ImmTAC) molecules as a model, we explored the impact of altering affinity for target and CD3 on the potency and specificity of the redirected T-cell response. This class of bispecifics binds specific target peptides presented by human leukocyte antigen on the cell surface via an affinity-enhanced T-cell receptor and can redirect T-cell activation with an anti-CD3 effector moiety. The data reveal that combining a strong affinity TCR with an intermediate affinity anti-CD3 results in optimal T-cell activation, while strong affinity of both targeting and effector domains significantly reduces maximum cytokine release. Moreover, by optimizing the affinity of both parts of the molecule, it is possible to improve the selectivity. These results could be effectively modelled based on kinetic proofreading with limited signalling. This model explained the experimental observation that strong binding at both ends of the molecules leads to reduced activity, through very stable target-bispecific-effector complexes leading to CD3 entering a non-signalling dark state. These findings have important implications for the design of anti-CD3-based bispecifics with optimal biophysical parameters for both activity and specificity.

Impact of Maximal Transurethral Resection on Pathological Outcomes at Cystectomy in a Large, Multi-institutional Cohort.

PURPOSE: While the presence of residual disease at the time of radical cystectomy for bladder cancer is an established prognostic indicator, controversy remains regarding the importance of maximal transurethral resection prior to neoadjuvant chemotherapy. We characterized the influence of maximal transurethral resection on pathological and survival outcomes using a large, multi-institutional cohort. MATERIALS AND METHODS: We identified 785 patients from a multi-institutional cohort undergoing radical cystectomy for muscle-invasive bladder cancer after neoadjuvant chemotherapy. We employed bivariate comparisons and stratified multivariable models to quantify the effect of maximal transurethral resection on pathological findings at cystectomy and survival. RESULTS: Of 785 patients, 579 (74%) underwent maximal transurethral resection. Incomplete transurethral resection was more frequent in patients with more advanced clinical tumor (cT) and nodal (cN) stage (P < .001 and P < .01, respectively), with more advanced ypT stage at cystectomy and higher rates of positive surgical margins (P < .01 and P < .05, respectively). In multivariable models, maximal transurethral resection was associated with downstaging at cystectomy (adjusted odds ratio 1.6, 95% CI 1.1-2.5). In Cox proportional hazards analysis, maximal transurethral resection was not associated with overall survival (adjusted HR 0.8, 95% CI 0.6-1.1). CONCLUSIONS: In patients undergoing transurethral resection for muscle-invasive bladder cancer prior to neoadjuvant chemotherapy, maximal resection may improve pathological response at cystectomy. However, the ultimate effects on long-term survival and oncologic outcomes warrant further investigation.

Treatment in the absence of disease reclassification among men on active surveillance for prostate cancer.

BACKGROUND: Maintaining men on active surveillance for prostate cancer can be challenging. Although most men who eventually undergo treatment have experienced clinical progression, a smaller subset elects treatment in the absence of disease reclassification. This study sought to understand factors associated with treatment in a large, contemporary, prospective cohort. METHODS: This study identified 1789 men in the Canary Prostate Cancer Active Surveillance Study cohort enrolled as of 2020 with a median follow-up of 5.6 years. Clinical and demographic data as well as information on patient-reported quality of life and urinary symptoms were used in multivariable Cox proportional hazards regression models to identify factors associated with the time to treatment RESULTS: Within 4 years of their diagnosis, 33% of men (95% confidence interval [CI], 30%-35%) underwent treatment, and 10% (95% CI, 9%-12%) were treated in the absence of reclassification. The most significant factor associated with any treatment was an increasing Gleason grade group (adjusted hazard ratio [aHR], 14.5; 95% CI, 11.7-17.9). Urinary quality-of-life scores were associated with treatment without reclassification (aHR comparing "mostly dissatisfied/terrible" with "pleased/mixed," 2.65; 95% CI, 1.54-4.59). In a subset analysis (n = 692), married men, compared with single men, were more likely to undergo treatment in the absence of reclassification (aHR, 2.63; 95% CI, 1.04-6.66). CONCLUSIONS: A substantial number of men with prostate cancer undergo treatment in the absence of clinical changes in their cancers, and quality-of-life changes and marital status may be important factors in these decisions. LAY SUMMARY: This analysis of men on active surveillance for prostate cancer shows that approximately 1 in 10 men will decide to be treated within 4 years of their diagnosis even if their cancer is stable. These choices may be related in part to quality-or-life or spousal concerns.

Threat vigilance and intrinsic amygdala connectivity.

A well-documented amygdala-dorsomedial prefrontal circuit is theorized to promote attention to threat ("threat vigilance"). Prior research has implicated a relationship between individual differences in trait anxiety/vigilance, engagement of this circuitry, and anxiogenic features of the environment (e.g., through threat-of-shock and movie-watching). In the present study, we predicted that-for those scoring high in self-reported anxiety and a behavioral measure of threat vigilance-this circuitry is chronically engaged, even in the absence of anxiogenic stimuli. Our analyses of resting-state fMRI data (N = 639) did not, however, provide evidence for such a relationship. Nevertheless, in our planned exploratory analyses, we saw a relationship between threat vigilance behavior (but not self-reported anxiety) and intrinsic amygdala-periaqueductal gray connectivity. Here, we suggest this subcortical circuitry may be chronically engaged in hypervigilant individuals, but that amygdala-prefrontal circuitry may only be engaged in response to anxiogenic stimuli.

Titrating the Smell of Fear: Initial Evidence for Dose-Invariant Behavioral, Physiological, and Neural Responses.

It is well accepted that emotional intensity scales with stimulus strength. Here, we used physiological and neuroimaging techniques to ask whether human body odor-which can convey salient social information-also induces dose-dependent effects on behavior, physiology, and neural responses. To test this, we first collected sweat from 36 males classified as low-, medium-, and high-fear responders. Next, in a double-blind within-subjects functional-MRI design, 31 women were exposed to three doses of fear-associated human chemosignals and neutral sweat while viewing face morphs varying between expressions of fear and disgust. Behaviorally, we found that all doses of fear-sweat volatiles biased participants toward perceiving fear in ambiguous morphs, a dose-invariant effect generally repeated across physiological and neural measures. Bayesian dose-response analysis indicated moderate evidence for the null hypothesis (except for the left amygdala), tentatively suggesting that the human olfactory system engages an all-or-none mechanism for tagging fear above a minimal threshold.

Characterising 'bounce-back' readmissions after radical cystectomy.

OBJECTIVE: To examine predictors of early readmissions after radical cystectomy (RC). Factors associated with preventable readmissions may be most evident in readmissions that occur within 3 days of discharge, commonly termed 'bounce-back' readmissions, and identifying such factors may inform efforts to reduce surgical readmissions. PATIENTS AND METHODS: We utilised the Healthcare Cost and Utilization Project's State Inpatient Databases to examine 1867 patients undergoing RC in 2009 and 2010, and identified all patients readmitted within 30 days of discharge. We assessed differences between patients experiencing bounce-back readmission compared to those readmitted 8-30 days after discharge using logistic regression models and also calculated abbreviated LACE scores to assess the utility of common readmissions risk stratification algorithms. RESULTS: The 30-day and bounce-back readmission rates were 28.4% and 5.6%, respectively. Although no patient or index hospitalisation characteristics were significantly associated with bounce-back readmissions in adjusted analyses, bounce-back patients did have higher rates of gastrointestinal (14.3% vs 6.7%, P = 0.02) and wound (9.5% vs 3.0%, P < 0.01) diagnoses, as well as increased index and readmission length of stay (5 vs 4 days, P = 0.01). Overall, the median abbreviated LACE score was 7, which fell into the moderate readmission risk category, and no difference was observed between readmitted and non-readmitted patients. CONCLUSION: One in five readmissions after RC occurs within 3 days of initial discharge, probably due to factors present at discharge. However, sociodemographic and clinical factors, as well as traditional readmission risk tools were not predictive of this bounce-back. Effective strategies to reduce bounce-back readmission must identify actionable clinical factors prior to discharge.

Characterising potential bone scan overuse amongst men treated with radical prostatectomy.

OBJECTIVES: To characterise bone scan use, and potential overuse, after radical prostatectomy (RP) using data from a large, national integrated delivery system. Overuse of imaging is well documented in the setting of newly diagnosed prostate cancer, but whether overuse persists after RP remains unknown. PATIENTS AND METHODS: We identified 12 269 patients with prostate cancer treated with RP between 2005 and 2008 using the Veterans Administration Central Cancer Registry. We used administrative and laboratory data to examine rates of bone scan use, including preceding prostate-specific antigen (PSA) levels, and receipt of adjuvant or salvage therapy. We then performed multivariable logistic regression to identify factors associated with post-RP bone scan use. RESULTS: At a median follow-up of 6.8 years, one in five men (22%) underwent a post-RP bone scan at a median PSA level of 0.2 ng/mL. Half of bone scans (48%) were obtained in men who did not receive further treatment with androgen-deprivation or radiation therapy. After adjustment, post-RP bone scan was associated with a prior bone scan (adjusted odds ratio [aOR] 1.55, 95% confidence interval [CI] 1.32-1.84), positive surgical margin (aOR 1.68, 95% CI 1.40-2.01), preoperative PSA level (aOR 1.02, 95% CI 1.01-1.03), as well as Hispanic ethnicity, Black race, and increasing D'Amico risk category, but not with age or comorbidity. CONCLUSION: We found a substantial rate of bone scan utilisation after RP. The majority were performed for PSA levels of <1 ng/mL where the likelihood of a positive test is low. More judicious use of imaging appears warranted in the post-RP setting.

Role of Post-Acute Care on Hospital Readmission After High-Risk Surgery.

BACKGROUND: Payment models, including the Hospital Readmissions Reduction Program and bundled payments, place pressures on hospitals to limit readmissions. Against this backdrop, we sought to investigate the association of post-acute care after major surgery and readmission rates. METHODS: We identified patients undergoing high-risk surgery (abdominal aortic aneurysm repair, coronary bypass grafting, aortic valve replacement, carotid endarterectomy, esophagectomy, pancreatectomy, lung resection, and cystectomy) from 2005 to 2010 using the Healthcare Cost and Utilization Project's State Inpatient Database. The primary outcome was readmission rates after major surgery. Secondary outcome was readmission length of stay. RESULTS: We identified 135,523 patients of whom 56,720 (42%) received post-acute care. Patients receiving post-acute care had higher readmission rates than those who were discharged home (16% versus 10%, respectively; P < 0.001). The risk-adjusted readmission length of stay was greatest for patients who received care from a skilled nursing facility, followed by those who received home care, and lowest for those who did not receive post-acute care (7.1 versus 5.4 versus 4.8 d, respectively; P < 0.001). CONCLUSIONS: The use of post-acute care was associated with higher readmission rates and higher readmission lengths of stay. Improving the support of patients in post-acute care settings may help reduce readmissions and readmission intensity.

The implications of baseline bone-health assessment at initiation of androgen-deprivation therapy for prostate cancer.

OBJECTIVES: To assess bone-density testing (BDT) use amongst prostate cancer survivors receiving androgen-deprivation therapy (ADT), and downstream implications for osteoporosis and fracture diagnoses, as well as pharmacological osteoporosis treatment in a national integrated delivery system. PATIENTS AND METHODS: We identified 17 017 men with prostate cancer who received any ADT between 2005 and 2014 using the Veterans Health Administration cancer registry and administrative data. We identified claims for BDT within a 3-year period of ADT initiation. We then used multivariable regression to examine the association between BDT use and incident osteoporosis, fracture, and use of pharmacological treatment. RESULTS: We found that a minority of patients received BDT (n = 2 502, 15%); however, the rate of testing increased to >20% by the end of the study period. Men receiving BDT were older at diagnosis and had higher-risk prostate cancer (both P < 0.001). Osteoporosis and fracture diagnoses, use of vitamin D ± calcium, and bisphosphonates were all more common in men who received BDT. After adjustment, BDT, and to a lesser degree ≥2 years of ADT, were both independently associated with incident osteoporosis, fracture, and osteoporosis treatment. CONCLUSIONS: BDT is rare amongst patients with prostate cancer treated with ADT in this integrated delivery system. However, BDT was associated with substantially increased treatment of osteoporosis indicating an underappreciated burden of osteoporosis amongst prostate cancer survivors initiating ADT. Optimising BDT use and osteoporosis management in this at-risk population appears warranted.

The effects of cystoscopy and hydrodistention on symptoms and bladder capacity in interstitial cystitis/bladder pain syndrome.

AIMS: The use of cystoscopy and hydrodistention in the management of interstitial cystitis/bladder pain syndrome (IC/BPS) varies widely between providers. Current evidence regarding the risks and benefits of hydrodistention, as well as the long term effects of repeated hydrodistention are not well established. We sought to characterize the effects of hydrodistention on IC/BPS symptoms as well as bladder capacity. METHODS: We retrospectively queried our institutional records for patients with non-ulcerative IC/BPS who underwent hydrodistention over an 11-year period to obtain demographic and clinical factors at the time of diagnosis and treatment. Symptom relief and bladder capacity changes were assessed, and multivariable models were used to predict response to treatment. RESULTS: There were 328 patients who underwent hydrodistention during the study period, of whom 36% received the procedure multiple times, and overall median follow-up was 38.6 months. Patients with repeated hydrodistentions were more likely to be female, have more comorbid pain disorders, and have trialed anticholinergic medications and intravesical instillations. No decrease in mean bladder capacity was observed over time (P = 0.40). Significant decreases in symptom scores were observed following the procedure on multiple questionnaires. CONCLUSIONS: Hydrodistention does not decrease bladder capacity even with multiple procedures, and measurably improves symptoms in some patients with IC/BPS. Continuing efforts to better identify those patients most likely to benefit from this procedure are justified.

Predictors and Cost of Readmission in Total Knee Arthroplasty.

BACKGROUND: The Comprehensive Care for Joint Replacement bundle was created to decrease total knee arthroplasty (TKA) cost. To help accomplish this, there is a focus on reducing TKA readmissions. However, there is a lack of national representative sample of all-payer hospital admissions to direct strategy, identify risk factors for readmission, and understand actual readmission cost. METHODS: We used the Nationwide Readmission Database to examine national readmission rates, predictors of readmission, and associated readmission costs for elective TKA procedures. We fit a multivariable logistic regression model to examine factors associated with readmission. Then, we determined mean readmission costs and calculated the readmission cost when distributed across the entire TKA population. RESULTS: We identified 224,465 patients having TKA across all states participating in the Nationwide Readmission Database. The mean unadjusted 30-day TKA readmission rate was 4%. The greatest predictors of readmission were congestive heart failure (odds ratio [OR] 2.51, 95% confidence interval [CI] 2.62-2.80), renal disease (OR 2.19, 95% CI 2.03-2.37), and length of stay greater than 4 days (OR 2.4, 95% CI 2.25-2.61). The overall median cost for each readmission was $6753 ± 175. Extrapolating the readmission cost for the entire TKA population resulted in the readmission cost being 2% of the overall 30-day procedure cost. CONCLUSIONS: A major focus of the Comprehensive Care for Joint Replacement bundle is improving cost and quality by limiting readmission rates. TKA readmissions are low and comprise a small percentage of total TKA cost, suggesting that they may not be the optimal measure of quality care or a significant driver of overall cost.

One-year postoperative resource utilization in sarcopenic patients.

BACKGROUND: It is well established that sarcopenic patients are at higher risk of postoperative complications and short-term health care utilization. Less well understood is how these patients fare over the long term after surviving the immediate postoperative period. We explored costs over the first postoperative year among sarcopenic patients. METHODS: We identified 1279 patients in the Michigan Surgical Quality Collaborative database who underwent inpatient elective surgery at a single institution from 2006-2011. Sarcopenia, defined by gender-stratified tertiles of lean psoas area, was determined from preoperative computed tomography scans using validated analytic morphomics. Data were analyzed to assess sarcopenia's relationship to costs, readmissions, discharge location, intensive care unit admissions, hospital length of stay, and mortality. Multivariate models were adjusted for patient demographics and surgical risk factors. RESULTS: Sarcopenia was independently associated with increased adjusted costs at 30, 90, and 180 but not 365 d. The difference in adjusted postsurgical costs between sarcopenic and nonsarcopenic patients was $16,455 at 30 d and $14,093 at 1 y. Sarcopenic patients were more likely to be discharged somewhere other than home (P < 0.001). Sarcopenia was not an independent predictor of increased readmission rates in the postsurgical year. CONCLUSIONS: The effects of sarcopenia on health care costs are concentrated in the immediate postoperative period. It may be appropriate to allocate additional resources to sarcopenic patients in the perioperative setting to reduce the incidence of negative postoperative outcomes.

Inhibition of CCL2 signaling in combination with docetaxel treatment has profound inhibitory effects on prostate cancer growth in bone.

The C-C chemokine ligand 2 (CCL2) stimulates migration, proliferation, and invasion of prostate cancer (PCa) cells, and its signaling also plays a role in the activation of osteoclasts. Therefore targeting CCL2 signaling in regulation of tumor progression in bone metastases is an area of intense research. The objective of our study was to investigate the efficacy of CCL2 blockade by neutralizing antibodies to inhibit the growth of PCa in bone. We used a preclinical model of cancer growth in the bone in which PCa C4-2B cells were injected directly into murine tibiae. Animals were treated for ten weeks with neutralizing anti-CCL2 antibodies, docetaxel, or a combination of both, and then followed an additional nine weeks. CCL2 blockade inhibited the growth of PCa in bone, with even more pronounced inhibition in combination with docetaxel. CCL2 blockade also resulted in increases in bone mineral density. Furthermore, our results showed that the tumor inhibition lasted even after discontinuation of the treatment. Our data provide compelling evidence that CCL2 blockade slows PCa growth in bone, both alone and in combination with docetaxel. These results support the continued investigations of CCL2 blockade as a treatment for advanced metastatic PCa.

Anxiety Shapes Amygdala-Prefrontal Dynamics During Movie Watching.

Background: A well-characterized amygdala-dorsomedial prefrontal circuit is thought to be crucial for threat vigilance during anxiety. However, engagement of this circuitry within relatively naturalistic paradigms remains unresolved. Methods: Using an open functional magnetic resonance imaging dataset (Cambridge Centre for Ageing Neuroscience; n = 630), we sought to investigate whether anxiety correlates with dynamic connectivity between the amygdala and dorsomedial prefrontal cortex during movie watching. Results: Using an intersubject representational similarity approach, we saw no effect of anxiety when comparing pairwise similarities of dynamic connectivity across the entire movie. However, preregistered analyses demonstrated a relationship between anxiety, amygdala-prefrontal dynamics, and anxiogenic features of the movie (canonical suspense ratings). Our results indicated that amygdala-prefrontal circuitry was modulated by suspense in low-anxiety individuals but was less sensitive to suspense in high-anxiety individuals. We suggest that this could also be related to slowed habituation or amplified anticipation. Moreover, a measure of threat-relevant attentional bias (accuracy/reaction time to fearful faces) demonstrated an association with connectivity and suspense. Conclusions: Overall, this study demonstrated the presence of anxiety-relevant differences in connectivity during movie watching, varying with anxiogenic features of the movie. Mechanistically, exactly how and when these differences arise remains an opportunity for future research.

Anxiety and amygdala connectivity during movie-watching.

Rodent and human studies have implicated an amygdala-prefrontal circuit during threat processing. One possibility is that while amygdala activity underlies core features of anxiety (e.g. detection of salient information), prefrontal cortices (i.e. dorsomedial prefrontal/anterior cingulate cortex) entrain its responsiveness. To date, this has been established in tightly controlled paradigms (predominantly using static face perception tasks) but has not been extended to more naturalistic settings. Consequently, using 'movie fMRI'-in which participants watch ecologically-rich movie stimuli rather than constrained cognitive tasks-we sought to test whether individual differences in anxiety correlate with the degree of face-dependent amygdala-prefrontal coupling in two independent samples. Analyses suggested increased face-dependent superior parietal activation and decreased speech-dependent auditory cortex activation as a function of anxiety. However, we failed to find evidence for anxiety-dependent connectivity, neither in our stimulus-dependent or -independent analyses. Our findings suggest that work using experimentally constrained tasks may not replicate in more ecologically valid settings and, moreover, highlight the importance of testing the generalizability of neuroimaging findings outside of the original context.

RapidHRV: an open-source toolbox for extracting heart rate and heart rate variability.

Heart rate and heart rate variability have enabled insight into a myriad of psychophysiological phenomena. There is now an influx of research attempting using these metrics within both laboratory settings (typically derived through electrocardiography or pulse oximetry) and ecologically-rich contexts (via wearable photoplethysmography, i.e., smartwatches). However, these signals can be prone to artifacts and a low signal to noise ratio, which traditionally are detected and removed through visual inspection. Here, we developed an open-source Python package, RapidHRV, dedicated to the preprocessing, analysis, and visualization of heart rate and heart rate variability. Each of these modules can be executed with one line of code and includes automated cleaning. In simulated data, RapidHRV demonstrated excellent recovery of heart rate across most levels of noise (>=10 dB) and moderate-to-excellent recovery of heart rate variability even at relatively low signal to noise ratios (>=20 dB) and sampling rates (>=20 Hz). Validation in real datasets shows good-to-excellent recovery of heart rate and heart rate variability in electrocardiography and finger photoplethysmography recordings. Validation in wrist photoplethysmography demonstrated RapidHRV estimations were sensitive to heart rate and its variability under low motion conditions, but estimates were less stable under higher movement settings.

Naloxegol versus Alvimopan for Enhancing Postoperative Recovery following Radical Cystectomy for Bladder Cancer.

INTRODUCTION: µ-Opioid-receptor antagonists are a standard component of enhanced recovery after surgery (ERAS) pathways following radical cystectomy (RC) as they reduce ileus and shorten length of stay (LOS). Prior studies have used alvimopan; however, naloxegol is a less expensive medication in the same class. We compared differences in postoperative outcomes between patients receiving alvimopan or naloxegol following RC. METHODS: We retrospectively reviewed all patients undergoing RC over 20 months at an academic center during which standard practice transitioned from using alvimopan to naloxegol, while maintaining all other components of our ERAS pathway. We utilized bivariate comparisons as well as negative binomial and logistic regression to compare return of bowel function, rates of ileus and LOS following RC. RESULTS: Of 117 eligible patients, 59 (50%) received alvimopan and 58 (50%) received naloxegol. There were no differences in baseline clinical, demographic or perioperative factors. Median postoperative LOS was 6 days in each group (p=0.3). Time to flatus (2 versus 2 days, p=0.2) and ileus (14% versus 17%, p=0.6) were similar between the alvimopan and naloxegol groups, respectively. In multivariable models controlling for patient and surgical factors, µ-opioid antagonist agent was associated with neither LOS nor ileus. Cost difference was -$344.20/day, equivalent to a $2,065.20 savings over a 6-day hospital stay with naloxegol. CONCLUSIONS: In patients undergoing RC managed with a standard ERAS pathway, there were no differences in postoperative recovery based on the use of alvimopan versus naloxegol. Substitution of naloxegol for alvimopan may allow for significant cost savings without compromising outcomes.

Trait anxiety does not correlate with metacognitive confidence or reminder usage in a delayed intentions task.

Setting external reminders provides a convenient way to reduce cognitive demand and ensure accurate retrieval of information for prospective tasks. Recent experimental evidence has demonstrated that the decision to offload cognitive information to external resources is guided by metacognitive belief, that is, individuals' confidence in their unaided ability. Other work has also suggested a relationship between metacognitive belief and trait anxiety. In the present study (N = 300), we bridged these two areas by investigating whether trait anxiety correlated with metacognitive belief and-consequently-propensity to offload information in a delayed intentions paradigm. Participants received a financial reward based on their ability to remember targets. However, participants could take a reduced reward per target if they decided to use reminders. We replicated previous findings that participants were biased to use more reminders than would be optimal, and this bias was correlated with metacognitive judgements. However, we show no evidence that trait anxiety held a relationship with metacognitive belief or reminder usage. Indeed, Bayesian analyses strongly favoured the null. Therefore, variation in self-reported trait anxiety does not necessarily influence confidence and strategy when participants remember delayed intentions.

NKTR-255, a novel polymer-conjugated rhIL-15 with potent antitumor efficacy.

BACKGROUND: NKTR-255 is a novel polyethylene glycol-conjugate of recombinant human interleukin-15 (rhIL-15), which was designed to retain all known receptor binding interactions of the IL-15 molecule. We explored the biologic and pharmacologic differences between endogenous IL-15 receptor α (IL-15Rα)-dependent (NKTR-255 and rhIL-15) and IL-15Rα-independent (precomplexed rhIL-15/IL-15Rα) cytokines. METHODS: In vitro pharmacological properties of rhIL-15, NKTR-255 and precomplex cytokines (rhIL-15/IL-15Rα and rhIL-15 N72D/IL-15Rα Fc) were investigated in receptor binding, signaling and cell function. In vivo pharmacokinetic (PK) and pharmacodynamic profile of the cytokines were evaluated in normal mice. Finally, immunomodulatory effect and antitumor activity were assessed in a Daudi lymphoma model. RESULTS: NKTR-255 and rhIL-15 exhibited similar in vitro properties in receptor affinity, signaling and leukocyte degranulation, which collectively differed from precomplexed cytokines. Notably, NKTR-255 and rhIL-15 stimulated greater granzyme B secretion in human peripheral blood mononuclear cells versus precomplexed cytokines. In vivo, NKTR-255 exhibited a PK profile with reduced clearance and a longer half-life relative to rhIL-15 and demonstrated prolonged IL-15R engagement in lymphocytes compared with only transient engagement observed for rhIL-15 and precomplexed rhIL-15 N72D/IL-15Rα Fc. As a consequent, NKTR-255 provided a durable and sustained proliferation and activation of natural killer (NK) and CD8+ T cells. Importantly, NKTR-255 is more effective than the precomplexed cytokine at inducing functionally competent, cytotoxic NK cells in the tumor microenvironment and the properties of NKTR-255 translated into superior antitumor activity in a B-cell lymphoma model versus the precomplexed cytokine. CONCLUSIONS: Our results show that the novel immunotherapeutic, NKTR-255, retains the full spectrum of IL-15 biology, but with improved PK properties, over rhIL-15. These findings support the ongoing phase 1 first-in-human trial (NCT04136756) of NKTR-255 in participants with relapsed or refractory hematologic malignancies, potentially advancing rhIL-15-based immunotherapies for the treatment of cancer.

NKTR-358: A novel regulatory T-cell stimulator that selectively stimulates expansion and suppressive function of regulatory T cells for the treatment of autoimmune and inflammatory diseases.

Impaired interleukin-2 (IL-2) production and regulatory T-cell dysfunction have been implicated as immunological mechanisms central to the pathogenesis of multiple autoimmune and inflammatory diseases. NKTR-358, a novel regulatory T-cell stimulator, is an investigational therapeutic that selectively restores regulatory T-cell homeostasis in these diseases. We investigated NKTR-358's selectivity for regulatory T-cells, receptor-binding properties, ex vivo and in vivo pharmacodynamics, ability to suppress conventional T-cell proliferation in mice and non-human primates, and functional activity in a murine model of systemic lupus erythematosus. In vitro, NKTR-358 demonstrated decreased affinity for IL-2Rα, IL-2Rß, and IL-2Rαß compared with recombinant human IL-2 (rhIL-2). A single dose of NKTR-358 in cynomolgus monkeys produced a greater than 15-fold increase in regulatory T-cells, and the increase lasted until day 14, while daily rhIL-2 administration for 5 days only elicited a 3-fold increase, which lasted until day 7. Repeated dosing of NKTR-358 over 6 months in cynomolgus monkeys elicited cyclical, robust increases in regulatory T-cells with no loss in drug activity over the course of treatment. Regulatory T-cells isolated from NKTR-358-treated mice displayed a sustained, higher suppression of conventional T-cell proliferation than regulatory T-cells isolated from vehicle-treated mice. NKTR-358 treatment in a mouse model (MRL/MpJ-Faslpr) of systemic lupus erythematosus for 12 weeks maintained elevated regulatory T-cells for the treatment duration and ameliorated disease progression. Together, these results suggest that NKTR-358 has the ability to elicit sustained and preferential proliferation and activation of regulatory T-cells without corresponding effects on conventional T-cells, with improved pharmacokinetics compared with rhIL-2.