Dosing Regimens of Immune Checkpoint Inhibitors: Attempts at Lower Dose, Less Frequency, Shorter Course

Thermosensitive Hydrogel Sustaining the Release of Lymph-Draining Oligonucleotide Adjuvant Polyplex Micelles Improves Systemic Cancer Immunotherapy

Immune checkpoint blockade (ICB) immunotherapies are a powerful tool in the clinical management of cancer, but response rates to ICB remain limited, and treatment-related toxicities can be significant. Therapeutic efficacy of ICB can be enhanced by delivering synergistic immunomodulators to tumor-draining lymph nodes (TdLNs). However, achieving sustained release of small molecule immunomodulators into the lymphatics and TdLNs remains challenging. To address this limitation, a sustained release system for delivering an oligonucleotide adjuvant to lymph nodes (LNs) was developed. CpG oligonucleotide was complexed with a redox-responsive cationic polymer and mixed with F127-g-Gelatin to generate a thermosensitive hydrogel that releases lymph-draining polyplex micelles in situ. This CpG/BPEI-SS-/F127-g-Gelatin (CpG-HG) system enhanced the quantity and duration of CpG delivery to TdLNs following locoregional administration compared with free drug and enabled targeted, potent, and prolonged immunomodulation within TdLNs from a single administration. This augmented, localized immune response synergized with systemic ICB treatment, both markedly amplifying the systemic circulating CD8+ T cell response and improving antitumor therapeutic efficacy while enabling ICB dose reduction. These results highlight the potential for this drug delivery system as an adjunct to existing clinical ICB protocols to improve patient outcomes.

Unmasking a Paradox: Roles of the PD-1/PD-L1 Axis in Alzheimer's Disease-Associated Neuroinflammation

Alzheimer's disease (AD) represents the most prevalent form of dementia, characterized by progressive cognitive impairment and chronic neuroinflammation. Immune checkpoint inhibitors (ICIs), including anti-programmed cell death (PD)-1 and anti-PD-L1, signify a revolutionary advancement in cancer treatment by preventing T-cell exhaustion; however, their therapeutic application in AD presents a conundrum. Hypothesis: Recent preclinical studies indicate that PD-1 inhibition in AD mouse models induces an interferon-gamma (IFN-γ)-mediated response, leading to increased recruitment of monocyte-derived macrophages into the brain, enhanced clearance of amyloid-beta (Aβ) plaques, and improved cognitive performance. Nonetheless, this therapeutic effect is counterbalanced by the potential for exacerbated neuroinflammation, as PD-1/PD-L1 blockade may potentiate pro-inflammatory T helper (Th)1 and Th17 responses. In this review, we critically discuss the pertinent pro-inflammatory and neuroprotective facets of T cell biology in the pathogenesis of AD, emphasizing the potential for modulation of the PD-1/PD-L1 axis to influence both Aβ clearance and the dynamics of neuroinflammatory processes. In summary, we determine that ICIs are promising tools for reducing AD pathology and improving cognition. However, it is essential to refine treatment protocols and carefully select patients to optimize neuroprotective effects while adequately considering inflammatory risks.

The clinical journey of belantamab mafodotin in relapsed or refractory multiple myeloma: lessons in drug development

Patients with relapsed/refractory multiple myeloma (RRMM) have a poor prognosis and a need remains for novel effective therapies. Belantamab mafodotin, an anti-B-cell maturation antigen antibody-drug conjugate, was granted accelerated/conditional approval for patients with RRMM who have received at least 4 prior lines of therapy, based on response rates observed in DREAMM-1/DREAMM-2. Despite the 41% response rate and durable responses observed with belantamab mafodotin in the Phase III confirmatory DREAMM-3 trial, the marketing license for belantamab mafodotin was later withdrawn from US and European markets when the trial did not meet its primary endpoint of superiority for progression-free survival compared with pomalidomide and dexamethasone. This review reflects on key lessons arising from the clinical journey of belantamab mafodotin in RRMM. It considers how incorporating longer follow-up in DREAMM-3 may have better captured the clinical benefits of belantamab mafodotin, particularly given its multimodal, immune-related mechanism of action with responses deepening over time. A non-inferiority hypothesis may have been more appropriate rather than superiority in the context of a monotherapy versus an active doublet therapy. Further, anticipation of, and planning for, non-proportional hazards arising from response heterogeneity may have mitigated loss of statistical power. With the aim of improving the efficacy of belantamab mafodotin, other Phase III trials in the RRMM development program (DREAMM-7 and DREAMM-8) proceeded to evaluate the synergistic potential of combination regimens in earlier lines of treatment. The aim was to increase the proportion of patients responding to belantamab mafodotin (and thus the likelihood of seeing a clear separation of the progression-free survival curve versus comparator regimens). Protocol amendments reflecting DREAMM-3 learnings could also be implemented prospectively on the combinations trials to optimize the follow-up duration and mitigate risk. The wider implications of the lessons learned for clinical research in RRMM and in earlier treatment settings are discussed.

Pembrolizumab hybrid dosing is non-inferior to flat dosing in advanced non-small cell lung cancer: a real-world, retrospective bicenter cohort study

BACKGROUND

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment but come with high costs. Alternative ICI dosing strategies could reduce costs without losing efficacy. However, clinical efficacy data are lacking.

METHODS

In this retrospective cohort trial, consecutive patients with advanced non-small cell lung cancer (NSCLC) who received ≥1 cycle pembrolizumab±chemotherapy at two tertiary institutions were included. Hybrid dosed patients received either 100, 150 or 200 mg pembrolizumab every 3 weeks or double every 6 weeks depending on their weight: <65 kg, 65-90 kg or >90 kg, respectively. Standard-of-care flat dosed patients received 200 mg every 3 weeks or 400 mg every 6 weeks. Overall survival (OS) and progression-free survival (PFS) were assessed by Kaplan-Meier estimation, compared by log-rank test and HRs were calculated with the Cox proportional hazards model in both unweighted and inverse probability of treatment weighted (IPTW) cohorts. Non-inferiority margin was set at an HR of 1.15.

RESULTS

In total, 375 patients and 391 patients were included and median follow-up was 43.1 and 61.0 months in the hybrid and flat dose cohort, respectively. OS was non-inferior in the hybrid dose cohort compared with the flat dose cohort: median 17.7 months (95% CI 14.9 to 20.9) vs 11.8 months (95% CI 9.3 to 13.8, HR 0.76, 95% CI 0.65 to 0.90, p<0.0001 for non-inferiority). After correcting for confounders by IPTW, OS remained non-inferior (HR 0.76, 95% CI 0.63 to 0.91, p<0.0001 for non-inferiority). PFS in the hybrid cohort was also non-inferior to the flat dose cohort with a median of 6.4 months (95% CI 5.7 to 7.7) vs 4.6 months (95% CI 3.9 to 5.5, HR 0.82, 95% CI 0.70 to 0.96, p<0.0001 for non-inferiority). In total, 26.2% (or 52.5 mg per cycle, p<0.0001) pembrolizumab was saved in the hybrid dose cohort accounting to US$36 331.36 per patient.

CONCLUSIONS

In this retrospective analysis of a large cohort of advanced NSCLC patients treated with pembrolizumab±chemotherapy, OS of hybrid dosed patients was non-inferior to flat dosed patients. OS remained non-inferior after correcting for possible confounding factors. This hybrid regimen resulted in significant savings of pembrolizumab and costs.

Navigating Recent Changes in Dosing Information: Dynamics of FDA-Approved Monoclonal Antibodies in Post-Marketing Realities

Monoclonal antibodies (mAbs) are critical components in the therapeutic landscape, but their dosing strategies often evolve post-approval as new data emerge. This review evaluates post-marketing label changes in dosing information for FDA-approved mAbs from January 2015 to September 2024, with a focus on both initial and extended indications. We systematically analyzed dosing modifications, categorizing them into six predefined groups: Dose increases or decreases, inclusion of new patient populations by body weight or age, shifts from body weight-based dosing to fixed regimens, and adjustments in infusion rates. Among the 86 mAbs evaluated, 21% (n = 18) exhibited changes in dosing information for the initial indication, with a median time to modification of 37.5 months (range: 5-76 months). Furthermore, for mAbs with extended indications (n = 26), 19.2% (n = 5) underwent dosing changes in their first extensions, with a median time to adjustment of 31 months (range: 8-71 months). Key drivers for these adjustments included optimizing therapeutic efficacy, addressing safety concerns, accommodating special populations, and enhancing patient convenience. We also discuss the role of model-informed drug development, real-world evidence, and pharmacogenomics in refining mAb dosing strategies. These insights underscore the importance of ongoing monitoring and data integration in the post-marketing phase, providing a foundation for future precision medicine approaches in mAb therapy.

Optimal Duration of Consolidation Durvalumab Following Chemoradiotherapy in Stage III Non-Small Cell Lung Cancer: A Multi-institutional Retrospective Study

BACKGROUND

Although durvalumab has shown promise in improving survival rates in patients with locally advanced non-small cell lung cancer (NSCLC), the ideal duration of treatment has yet to be established.

OBJECTIVE

The primary objective of this study was to determine the optimal number of durvalumab cycles following definitive chemoradiotherapy for locally advanced NSCLC.

PATIENTS AND METHODS

A total of 178 patients who received chemoradiotherapy for stage III NSCLC at 15 institutions were retrospectively analyzed. Progression-free survival (PFS) and overall survival (OS) were assessed according to the number of consolidation durvalumab cycles by landmark analysis. Landmark analyses were performed at 3-month intervals from the start of durvalumab treatment to 9 months.

RESULTS

The median number of durvalumab cycles was 16 (range 1-27). PFS and OS were significantly better in patients who received ≥20 cycles of durvalumab than in those who did not (p < 0.001 and p < 0.001, respectively). In landmark analysis, significant differences were observed in PFS from 0 to 6 months and OS from 3 to 6 months between patients who continued durvalumab after the time point and those who did not. However, there were no significant differences in PFS or OS between patients who received 13-19 or ≥20 cycles of durvalumab at 9 months.

CONCLUSIONS

Durvalumab should be administered for more than 6 months to contribute to the main benefits of consolidation therapy following chemoradiotherapy.

Metabolic modulation of melanoma enhances the therapeutic potential of immune checkpoint inhibitors

Introduction

Lactate is a pivotal molecule with diverse functions in the metabolic reprogramming of cancer cells. Beyond its role in metabolism, lactate exerts a modulatory effect within the tumor microenvironment; it is utilized by stromal cells and has been implicated in the suppression of the immune response against the tumor.

Methods

Using in vitro assays (including flow cytometry, live-cell imaging and metabolic analyses), the impact of lactate dehydrogenase inhibitors (LDHIs) on melanoma cells were assessed. The therapeutic potential of LDHIs with immune checkpoint inhibitors (ICIs) were tested in vivo in murine models of melanoma tumors.

Results

A potent anti-proliferative effect (via both cell cycle alterations and enhanced apoptosis) of LDHIs, Oxamate (Oxa) and methyl 1-hydroxy-6-phenyl-4-(trifluoromethyl)-1H-indole-2-carboxylate (NHI-2), was found upon treatment of melanoma cell lines. Using a combination of Oxa and NHI-2, a synergistic effect to inhibit proliferation, glycolysis, and ATP production was observed. Metabolic analysis revealed significant alteration in glycolysis and oxidative phosphorylation, while metabolite profiling emphasized consequential effects on lactate metabolism and induced energy depletion by LDHIs. Detection of increased RANTES and MCP-1, with Oxa and NHI-2 treatment, prompted the consideration of combining LDHIs with ICIs. In vivo studies using a murine B78 melanoma tumor model revealed a significant improvement in treatment efficacy when LDHIs were combined with ICIs.

Conclusions

These findings propose the potential of targeting lactate metabolism to enhance the efficacy of ICI treatments in patients with melanoma.

"Getting the Dose Right"-Revisiting the Topic With Focus on Biologic Agents

Nearly two decades after the Peck and Cross article '"Getting the dose right: facts, a blueprint, and encouragements" was published, a review of dose recommendations for biologics shows that the success in getting the dose right appears to have improved given the relatively low incidence of drug withdrawals and dosing/label changes. However, the clinical experience with monoclonal antibodies (MAbs) following approval has been less than perfect. In inflammatory diseases, the disease burden changes with time and high treatment failure rates have been reported. In addition, the use of concomitant steroids and immunosuppressant drugs with MAbs is common. These concomitant agents have their own safety issues and many immunosuppressant agents are not well-tolerated although they have been shown to reduce the incidence of anti-drug antibodies (ADA). This same complexity is seen in MAbs used in oncology as well, although with these agents the doses appear to be higher than needed, which results in high treatment costs and incidence of adverse events. Given the complexity of MAb pharmacokinetics, which makes providing a detailed description of dose options difficult, product labeling should include the options for alternative dose strategies and potentially include the use of therapeutic drug monitoring with dose individualization which have been shown to improve clinical response and reduce the incidence of ADA. So, while the recommended dosing for biologics seems improved over the issues noted 17 years ago, we still have some work to do.

Hit it hard: qualitative patient perspectives on the optimisation of immune checkpoint inhibition

BACKGROUND

Immune checkpoint inhibitors have transformed the treatment landscape of many cancers, including melanoma and renal cell carcinoma (RCC). Randomised trials are evaluating outcomes from reduced ICI treatment schedules with the aim of improving quality of life, tolerability, and cost-effectiveness. This study aims to provide insight into patient and carer's perspectives of these trials.

METHODS

Seven focus groups were conducted with 31 people with stage IV melanoma, RCC, or caregivers for people receiving ICI. Transcripts were analysed using reflexive thematic analysis.

RESULTS

Three themes were generated: 1) "Treatment and clinic visits provide reassurance": reducing hospital visits may not improve quality of life. 2) "Assessment of personal risk versus benefit": the decision to participate in an ICI optimisation trial is influenced by treatment response, experience of toxicity and perceived logistical benefits based on the individual's circumstances. 3) "Pre-existing experience and beliefs about how treatment and trials work", including the belief that more treatment is better, influence views around ICI optimisation trials.

CONCLUSION

This study provides insight into recruitment challenges and recommends strategies to enhance recruitment for ongoing ICI optimisation trials. These findings will influence the design of future ICI optimisation trials ensuring they are acceptable to patients.

Lipid-based nanosystems: the next generation of cancer immune therapy

Immunotherapy has become an important part of the oncotherapy arsenal. Its applicability in various cancer types is impressive, as well as its use of endogenous mechanisms to achieve desired ends. However, off-target or on-target-off-tumor toxicity, limited activity, lack of control in combination treatments and, especially for solid tumors, low local accumulation, have collectively limited clinical use thereof. These limitations are partially alleviated by delivery systems. Lipid-based nanoparticles (NPs) have emerged as revolutionary carriers due to favorable physicochemical characteristics, with specific applications and strengths particularly useful in immunotherapeutic agent delivery. The aim of this review is to highlight the challenges faced by immunotherapy and how lipid-based NPs have been, and may be further utilized to address such challenges. We discuss recent fundamental and clinical applications of NPs in a range of areas and provide a detailed discussion of the main obstacles in immune checkpoint inhibition therapies, adoptive cellular therapies, and cytokine therapies. We highlight how lipid-based nanosystems could address these through either delivery, direct modulation of the immune system, or targeting of the immunosuppressive tumor microenvironment. We explore advanced and emerging liposomal and lipid nanoparticle (LNP) systems for nucleic acid delivery, intrinsic and extrinsic stimulus-responsive formulations, and biomimetic lipid-based nanosystems in immunotherapy. Finally, we discuss the key challenges relating to the clinical use of lipid-based NP immunotherapies, suggesting future research directions for the near term to realize the potential of these innovative lipid-based nanosystems, as they become the crucial steppingstone towards the necessary enhancement of the efficacy of immunotherapy.

Gender Difference in sidE eFfects of ImmuNotherapy: a possible clue to optimize cancEr tReatment (G-DEFINER): study protocol of an observational prospective multicenter study

BACKGROUND

Immune checkpoint inhibitors (ICIs) have significantly improved outcomes in various cancers. ICI treatment is associated with the incidence of immune-related adverse events (irAEs) which can affect any organ. Data on irAEs occurrence in relation to sex- differentiation and their association with gender-specific factors are limited.

AIMS

The primary objective of the G-DEFINER study is to compare the irAEs incidence in female and male patients who undergo ICI treatment. Secondary objectives are: to compare the irAEs incidence in pre- and postmenopausal female patients; to compare the irAEs incidence in female and male patients according to different clinical and gender-related factors (lifestyle, psychosocial, and behavioral factors). Exploratory objectives of the study are to compare and contrast hormonal, gene-expression, SNPs, cytokines, and gut microbiota profiles in relation to irAEs incidence in female and male patients.

METHODS AND RESULTS

The patients are recruited from Fondazione IRCCS Istituto Nazionale dei Tumori, Italy, St Vincent's University Hospital, Ireland, Oslo University Hospital, Norway, and Karolinska Insitutet/Karolinska University Hospital, Sweden. The inclusion of patients was delayed due to the Covid pandemic, leading to a total of 250 patients recruited versus a planned number of 400 patients. Clinical and translational data will be analyzed.

INTERPRETATION

The expected outcomes are to improve the management of cancer patients treated with ICIs, leading to more personalized clinical approaches that consider potential toxicity profiles. The real world nature of the trial makes it highly applicable for timely irAEs diagnosis.

Mitigating non-genetic resistance to checkpoint inhibition based on multiple states of immune exhaustion

Despite the revolutionary impact of immune checkpoint inhibition on cancer therapy, the lack of response in a subset of patients, as well as the emergence of resistance, remain significant challenges. Here we explore the theoretical consequences of the existence of multiple states of immune cell exhaustion on response to checkpoint inhibition therapy. In particular, we consider the emerging understanding that T cells can exist in various states: fully functioning cytotoxic cells, reversibly exhausted cells with minimal cytotoxicity, and terminally exhausted cells. We hypothesize that inflammation augmented by drug activity triggers transitions between these phenotypes, which can lead to non-genetic resistance to checkpoint inhibitors. We introduce a conceptual mathematical model, coupled with a standard 2-compartment pharmacometric (PK) model, that incorporates these mechanisms. Simulations of the model reveal that, within this framework, the emergence of resistance to checkpoint inhibitors can be mitigated through altering the dose and the frequency of administration. Our analysis also reveals that standard PK metrics do not correlate with treatment outcome. However, we do find that levels of inflammation that we assume trigger the transition from the reversibly to terminally exhausted states play a critical role in therapeutic outcome. A simulation of a population that has different values of this transition threshold reveals that while the standard high-dose, low-frequency dosing strategy can be an effective therapeutic design for some, it is likely to fail a significant fraction of the population. Conversely, a metronomic-like strategy that distributes a fixed amount of drug over many doses given close together is predicted to be effective across the entire simulated population, even at a relatively low cumulative drug dose. We also demonstrate that these predictions hold if the transitions between different states of immune cell exhaustion are triggered by prolonged antigen exposure, an alternative mechanism that has been implicated in this process. Our theoretical analyses demonstrate the potential of mitigating resistance to checkpoint inhibitors via dose modulation.

Fixed Versus Body-Sized-Based Dosing of Monoclonal Antibodies

Monoclonal antibody products are an increasing portion of novel drug approvals. The labeling of initial drug approvals frequently involves body-size-based rather than fixed-dose administration regimens for adults without clear rationale for doing so. This presents challenges when prescribing these products for patients with extremes of body habitus who constitute a small portion of enrollment in pre-approval investigations. Fixed-dose regimens allow for standardized preparation with the potential to reduce the risk of calculation errors, drug waste, and make home administration more practical. Fixed-dose rather than body-size-based monoclonal antibody regimens should serve as the initial approach in early phase 1 clinical trials.

Combination checkpoint blockade and laser interstitial thermal therapy in radiographically progressive non-small cell lung cancer brain metastases

Background

Laser interstitial thermal therapy (LITT) is a minimally invasive surgical treatment being employed frequently for radiographically progressive brain metastases. Considerable interest exists in combining LITT-mediated in situ vaccination to license immune checkpoint blockade (ICB). No studies have examined the clinical feasibility of this combination in brain metastases.

Methods

All patients receiving LITT for radiographically progressive non-small cell lung carcinoma (NSCLC) brain metastases at a single center from 2015 to 2023 were retrospectively reviewed. Combination therapy was defined as ICB within 6 weeks of LITT. Clinical data, post-LITT freedom from local progression, and overall survival (OS) were collected. Adverse events (AEs) were evaluated according to Common Terminology Criteria.

Results

Eighteen patients received LITT + ICB for a total of 19 lesions. The median time between therapies was 2.29 weeks (range 0.85-5.98). In comparison to NSCLC patients receiving LITT alone or with targeted therapy (LITT only) (n = 25), there was no decrement in procedural outcomes. Patients receiving LITT + ICB discontinued steroids at a median of 11 (4-147) days post-LITT vs. 24 (3-242) days for patients receiving LITT only (P = .62). At study cutoff, the local control rate was 18/19 (94.7%) lesions in the LITT + ICB group and 22/25 (88.0%) in the LITT only group. There were 3 and 5 AEs ≥Grade 3 in the LITT + ICB and LITT-only groups, respectively.

Conclusions

Combination of LITT and ICB does not compromise procedural outcomes or time to steroid discontinuation in NSCLC. Prospective studies are needed to assess biomarkers of immune response.

Association of CD8 + T cells expressing nivolumab-free PD-1 with clinical status in a patient with relapsed refractory classical Hodgkin lymphoma

A 37-year-old man with refractory classical Hodgkin lymphoma (cHL) underwent PD-1 blockade therapy with nivolumab, which resulted in a partial response. However, treatment was discontinued due to immune-related adverse events (irAEs), including myasthenia gravis and myositis. Retreatment with nivolumab resulted in a complete metabolic response and hepatic irAE. Subsequently, nivolumab was administered at extended dosing intervals. Intermittent infusion of ten doses of nivolumab for a total dose of 2400 mg/body helped control the relapsed/refractory cHL over three years. During nivolumab treatment, disease progression and emergence of irAEs were associated with the proportion of CD8 + T cells expressing nivolumab-free PD-1 relative to the total number of CD8 + T cells. The findings in this nivolumab-sensitive patient highlight the clinical utility of monitoring immune cells expressing nivolumab-free PD-1 in patients with cHL who have been treated with nivolumab and have experienced irAEs.

Comparison of the effectiveness of integrative immunomodulatory treatments and conventional therapies on the survival of selected gastrointestinal cancer patients

In the last decade, the use of immunomodulating treatments (IMT) at integrative oncology providers (IOP) increased. IMTs are used to modulate the tumor microenvironment, which might lead to increased response-to-treatment, and the indication of immune checkpoint inhibitors might also be widened. The efficacy and safety of IMTs in advanced/metastatic gastrointestinal cancers were compared with conventional chemo(radio)therapy (CT). 21 colorectal- (CRC), 14 pancreatic- (PC), 5 cholangiocellular- (CCC), 5 gastric- (GC) and 4 esophageal cancer (EC) patients received IMT. IMT and CT were compared in CRC and PC. CT was administered at an academic oncology center. After the initiation of IMT, a median survival of ~ 20 (CRC, PC and EC) and ~ 10 months (CCC and GC) was observed. Of the IMTs, locoregional modulated electro-hyperthermia had the most positive effect on overall survival (HR: 0.3055; P = 0.0260), while fever-inducing interleukin-2, and low-dose ipilimumab showed a positive tendency. IMT was superior to CT in PC (HR: 0.1974; P = 0.0013), while modest effect was detected in CRC (HR: 0.7797; P = 0.4710). When the whole study population was analyzed, IMTs showed minimal effect on patient survival, still CT had the greatest effect if introduced as early as possible (HR: 0.0624; P < 0.0001). The integrative IMTs in the presented form have mild impact on gastrointestinal cancer patients' survival, however, we observed its benefit in PC, which warrants further investigations.

Interventional pharmacoeconomics for immune checkpoint inhibitors through alternative dosing strategies

Immune checkpoint inhibitors (ICIs) are approved for the treatment of a variety of cancer types. The doses of these drugs, though approved by the Food and Drug Administration (FDA), have never been optimised, likely leading to significantly higher doses than required for optimal efficacy. Dose optimisation would hypothetically decrease the risk, severity, and duration of immune-related adverse events, as well as provide an opportunity to reduce costs through interventional pharmacoeconomic strategies such as off-label dose reductions or less frequent dosing. We summarise existing evidence for ICI dose optimisation to advocate for the role of interventional pharmacoeconomics.

Natural Killer Cell Engagers (NKCEs): a new frontier in cancer immunotherapy

Natural Killer (NK) cells are a type of innate lymphoid cells that play a crucial role in immunity by killing virally infected or tumor cells and secreting cytokines and chemokines. NK cell-mediated immunotherapy has emerged as a promising approach for cancer treatment due to its safety and effectiveness. NK cell engagers (NKCEs), such as BiKE (bispecific killer cell engager) or TriKE (trispecific killer cell engager), are a novel class of antibody-based therapeutics that exhibit several advantages over other cancer immunotherapies harnessing NK cells. By bridging NK and tumor cells, NKCEs activate NK cells and lead to tumor cell lysis. A growing number of NKCEs are currently undergoing development, with some already in clinical trials. However, there is a need for more comprehensive studies to determine how the molecular design of NKCEs affects their functionality and manufacturability, which are crucial for their development as off-the-shelf drugs for cancer treatment. In this review, we summarize current knowledge on NKCE development and discuss critical factors required for the production of effective NKCEs.

In Silico Re-Optimization of Atezolizumab Dosing Using Population Pharmacokinetic Simulation and Exposure-Response Simulation

Atezolizumab, a humanized monoclonal antibody against programmed cell death ligand 1 (PD-L1), was initially approved in 2016, around the same time that the sponsor published the minimum serum concentration to maintain the saturation of receptor occupancy (6 μg/mL). The initially approved dose regimen of 1200 mg every 3 weeks (q3w) was subsequently modified to 840 mg q2w or 1680 mg q4w through pharmacokinetic simulations. Yet, each standard regimen yields steady-state trough concentrations (CMIN,SS ) far exceeding (≈ 40-fold) the stated target concentration. Additionally, the steady-state area under the plasma drug concentration-time curve (AUCSS ) at 1200 mg q3w was significantly (P = .027) correlated with the probability of adverse events of special interest (AESIs) in patients with non-small cell lung cancer (NSCLC) and, coupled with excess exposure, this provides incentive to explore alternative dose regimens to lower the exposure burden while maintaining an effective CMIN,SS . In this study, we first identified 840 mg q6w as an extended-interval regimen that could robustly maintain a serum concentration of 6 μg/mL (≥99% of virtual patients simulated, n = 1000), then applied this regimen to an approach that administers 2 "loading doses" of standard-interval regimens for a future clinical trial aiming to personalize dose regimens. Each standard dose was simulated for 2 loading doses, then 840 mg q6w thereafter; all yielded cycle-7 CMIN,SS values of >6 μg/mL in >99% of virtual patients. Further, the AUCSS from 840 mg q6w resulted in a flattening (P = .63) of the exposure-response relationship with adverse events of special interest (AESIs). We next aim to verify this in a clinical trial seeking to validate extended-interval dosing in a personalized approach using therapeutic drug monitoring.

Development and pharmacokinetic assessment of a fully canine anti-PD-1 monoclonal antibody for comparative translational research in dogs with spontaneous tumors

PD-1 checkpoint inhibitors have revolutionized the treatment of patients with different cancer histologies including melanoma, renal cell carcinoma, and non-small cell lung carcinoma. However, only a subset of patients show a dramatic clinical response to treatment. Despite intense biomarker discovery efforts, no single robust, prognostic correlation has emerged as a valid outcome predictor. Immune competent, pet dogs develop spontaneous tumors that share similar features to human cancers including chromosome aberrations, molecular subtypes, immune signatures, tumor heterogeneity, metastatic behavior, and chemotherapeutic response. As such, they represent a valuable parallel patient population in which to investigate predictive biomarkers of checkpoint inhibition. However, the lack of a validated, non-immunogenic, canine anti-PD-1 antibody for pre-clinical use hinders this comparative approach and prevents potential clinical benefits of PD-1 blockade being realized in the veterinary clinic. To address this, fully canine single-chain variable fragments (scFvs) that bind canine (c)PD-1 were isolated from a comprehensive canine scFv phage display library. Lead candidates were identified that bound with high affinity to cPD-1 and inhibited its interaction with canine PD-L1 (cPD-L1). The lead scFv candidate re-formatted into a fully canine IgGD reversed the inhibitory effects of cPD-1:cPD-L1 interaction on canine chimeric antigen receptor (CAR) T cell function. In vivo administration showed no toxicity and revealed favorable pharmacokinetics for a reasonable dosing schedule. These results pave the way for clinical trials with anti-cPD-1 in canine cancer patients to investigate predictive biomarkers and combination regimens to inform human clinical trials and bring a promising checkpoint inhibitor into the veterinary armamentarium.

Immune checkpoint inhibitors as mediators for immunosuppression by cancer-associated fibroblasts: A comprehensive review

The tumor microenvironment (TME) is a significant contributor to cancer progression containing complex connections between cellular and chemical components and provides a suitable substrate for tumor growth and development. Growing evidence shows targeting tumor cells while ignoring the surrounding TME is not effective enough to overcome the cancer disease. Fibroblasts are essential sentinels of the stroma that due to certain conditions in TME, such as oxidative stress and local hypoxia, become activated, and play the prominent role in the physical support of tumor cells and the enhancement of tumorigenesis. Activated fibroblasts in TME, defined as cancer-associated fibroblasts (CAFs), play a crucial role in regulating the biological behavior of tumors, such as tumor metastasis and drug resistance. CAFs are highly heterogeneous populations that have different origins and, in addition to their role in supporting stromal cells, have multiple immunosuppressive functions via a membrane and secretory patterns. The secretion of different cytokines/chemokines, interactions that mediate the recruitment of regulatory immune cells and the reprogramming of an immunosuppressive function in immature myeloid cells are just a few examples of how CAFs contribute to the immune escape of tumors through various direct and indirect mechanisms on specific immune cell populations. Moreover, CAFs directly abolish the role of cytotoxic lymphocytes. The activation and overexpression of inhibitory immune checkpoints (iICPs) or their ligands in TME compartments are one of the main regulatory mechanisms that inactivate tumor-infiltrating lymphocytes in cancer lesions. CAFs are also essential players in the induction or expression of iICPs and the suppression of immune response in TME. Based on available studies, CAF subsets could modulate immune cell function in TME through iICPs in two ways; direct expression of iICPs by activated CAFs and indirect induction by production soluble and then upregulation of iICPs in TME. With a focus on CAFs’ direct and indirect roles in the induction of iICPs in TME as well as their use in immunotherapy and diagnostics, we present the evolving understanding of the immunosuppressive mechanism of CAFs in TME in this review. Understanding the complete picture of CAFs will help develop new strategies to improve precision cancer therapy.

What is the optimal duration of immune checkpoint inhibitors in malignant tumors?

Immunotherapy, represented by immune checkpoint inhibitors (ICIs), has made a revolutionary difference in the treatment of malignant tumors, and considerably extended patients' overall survival (OS). In the world medical profession, however, there still reaches no clear consensus on the optimal duration of ICIs therapy. As reported, immunotherapy response patterns, immune-related adverse events (irAEs) and tumor stages are all related to the diversity of ICIs duration in previous researches. Besides, there lacks clear clinical guidance on the intermittent or continuous use of ICIs. This review aims to discuss the optimal duration of ICIs, hoping to help guide clinical work based on the literature.