CRABP2 reduces the sensitivity of Olaparib in ovarian cancer by downregulating Caspase-8 and decreasing the production of reactive oxygen species

Poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors, such as Olaparib, have been pivotal in treating BRCA-deficient ovarian cancer. However, their efficacy is limited in over 40% of BRCA-deficient patients, with acquired resistance posing new clinical challenges. To address this, we employed bioinformatics methods to identify key genes impacting Olaparib sensitivity in ovarian cancer. Through comprehensive analysis of public databases including GEO, CPTAC, Kaplan Meier Plotter, and CCLE, we identified CRABP2 as significantly upregulated at both mRNA and protein levels in ovarian cancer, correlating with poor prognosis and decreased Olaparib sensitivity. Using colony formation and CCK-8 assays, we confirmed that CRABP2 knockdown in OVCAR3 and TOV112D cells enhanced sensitivity to Olaparib. Additionally, 4D label-free quantitative proteomics analysis, GSEA, and GO/KEGG analysis revealed CRABP2's involvement in regulating oxidation signals. Flow cytometry, colony formation assays, and western blotting demonstrated that CRABP2 knockdown promoted ROS production by activating Caspase-8, thereby augmenting Olaparib sensitivity and inhibiting ovarian cancer cell proliferation. Moreover, in xenograft models, CRABP2 knockdown significantly suppressed tumorigenesis and enhanced Olaparib sensitivity, with the effect being reversed upon Caspase-8 knockdown. These findings suggest that CRABP2 may modulate Olaparib sensitivity in ovarian cancer through the Caspase-8/ROS axis, highlighting its potential as a target for Olaparib sensitization.

Adagrasib Treatment After Sotorasib-Related Hepatotoxicity in Patients With KRASG12C-Mutated Non-Small Cell Lung Cancer: A Case Series and Literature Review

PURPOSE

KRAS is the most commonly mutated driver oncogene in non-small cell lung cancer (NSCLC). Sotorasib and adagrasib, KRASG12C inhibitors, have been granted accelerated US approval; however, hepatotoxicity is a common side effect with higher rates in patients treated with sotorasib proximal to checkpoint inhibitor (CPI) therapy. The aim of this study was to assess the feasibility and safety of adagrasib after discontinuation of sotorasib because of treatment-related grade 3 hepatotoxicity through real-world and clinical cases.

METHODS

Medical records from five patients treated in real-world settings were retrospectively reviewed. Patients had locally advanced or metastatic KRASG12C-mutated NSCLC and received adagrasib after sotorasib in the absence of extracranial disease progression. Additional data were collected for 12 patients with KRASG12C-mutated NSCLC enrolled in a phase Ib cohort of the KRYSTAL-1 study and previously treated with sotorasib. The end points associated with both drugs included timing and severity of hepatotoxicity, best overall response, and duration of therapy.

RESULTS

All patients were treated with CPIs followed by sotorasib (initiated 0-64 days after CPI). All five real-world patients experienced hepatotoxicity with sotorasib that led to treatment discontinuation, whereas none experienced treatment-related hepatotoxicity with subsequent adagrasib treatment. Three patients from KRYSTAL-1 transitioned from sotorasib to adagrasib because of hepatotoxicity; one experienced grade 3 ALT elevation on adagrasib that resolved with therapy interruption and dose reduction.

CONCLUSION

Adagrasib may have a distinct hepatotoxicity profile from sotorasib and is more easily combined with CPIs either sequentially or concurrently. These differences may be used to inform clinical decisions regarding an initial KRASG12C inhibitor for patients who recently discontinued a CPI or experience hepatotoxicity on sotorasib.

FSP1 inhibition enhances olaparib sensitivity in BRCA-proficient ovarian cancer patients via a nonferroptosis mechanism

Poly ADP-ribose polymerase inhibitors (PARPis) exhibit promising efficacy in patients with BRCA mutations or homologous repair deficiency (HRD) in ovarian cancer (OC). However, less than 40% of patients have HRD, it is vital to expand the indications for PARPis in BRCA-proficient patients. Ferroptosis suppressor protein 1 (FSP1) is a key protein in a newly identified ferroptosis-protective mechanism that occurs in parallel with the GPX4-mediated pathway and is associated with chemoresistance in several cancers. Herein, FSP1 is reported to be negatively correlated with the prognosis in OC patients. Combination therapy comprising olaparib and iFSP1 (a FSP1 inhibitor) strongly inhibited tumour proliferation in BRCA-proficient OC cell lines, patient-derived organoids (PDOs) and xenograft mouse models. Surprisingly, the synergistic killing effect could not be reversed by ferroptosis inhibitors, indicating that mechanisms other than ferroptosis were responsible for the synergistic lethality. In addition, cotreatment was shown to induce increased γH2A.X foci and to impair nonhomologous end joining (NHEJ) activity to a greater extent than did any single drug. Mass spectrometry and immunoprecipitation analyses revealed that FSP1 interacted with Ku70, a classical component recruited to and occupying the end of double-strand breaks (DSBs) in the NHEJ process. FSP1 inhibition decreased Ku70 PARylation, impaired subsequent DNA-PKcs recruitment to the Ku complex at DSB sites and was rescued by restoring PARylation. These findings unprecedentedly reveal a novel role of FSP1 in DNA damage repair and provide new insights into how to sensitize OC patients to PARPi treatment.

Cell cycle plasticity underlies fractional resistance to palbociclib in ER+/HER2- breast tumor cells

The CDK4/6 inhibitor palbociclib blocks cell cycle progression in Estrogen receptor-positive, human epidermal growth factor 2 receptor-negative (ER+/HER2-) breast tumor cells. Despite the drug's success in improving patient outcomes, a small percentage of tumor cells continues to divide in the presence of palbociclib-a phenomenon we refer to as fractional resistance. It is critical to understand the cellular mechanisms underlying fractional resistance because the precise percentage of resistant cells in patient tissue is a strong predictor of clinical outcomes. Here, we hypothesize that fractional resistance arises from cell-to-cell differences in core cell cycle regulators that allow a subset of cells to escape CDK4/6 inhibitor therapy. We used multiplex, single-cell imaging to identify fractionally resistant cells in both cultured and primary breast tumor samples resected from patients. Resistant cells showed premature accumulation of multiple G1 regulators including E2F1, retinoblastoma protein, and CDK2, as well as enhanced sensitivity to pharmacological inhibition of CDK2 activity. Using trajectory inference approaches, we show how plasticity among cell cycle regulators gives rise to alternate cell cycle "paths" that allow individual tumor cells to escape palbociclib treatment. Understanding drivers of cell cycle plasticity, and how to eliminate resistant cell cycle paths, could lead to improved cancer therapies targeting fractionally resistant cells to improve patient outcomes.

Olaparib for the Treatment of Patients With Metastatic Castration-Resistant Prostate Cancer and Alterations in BRCA1 and/or BRCA2 in the PROfound Trial

Olaparib improved PFS and OS across subgroups of BRCA1/2mut #prostatecancer patients in the PROFOUND phase III trial.

Palbociclib: Safe and Effective in an 85-Year-Old Female with Metastatic Bilateral Breast Cancer

Null.

The impact of the BCR-ABL oncogene in the pathology and treatment of chronic myeloid leukemia

Chronic Myeloid Leukemia (CML) is characterized by chromosomal aberrations involving the fusion of the BCR and ABL genes on chromosome 22, resulting from a reciprocal translocation between chromosomes 9 and 22. This fusion gives rise to the oncogenic BCR-ABL, an aberrant tyrosine kinase identified as Abl protein. The Abl protein intricately regulates the cell cycle by phosphorylating protein tyrosine residues through diverse signaling pathways. In CML, the BCR-ABL fusion protein disrupts the first exon of Abl, leading to sustained activation of tyrosine kinase and resistance to deactivation mechanisms. Pharmacological interventions, such as imatinib, effectively target BCR-ABL's tyrosine kinase activity by binding near the active site, disrupting ATP binding, and inhibiting downstream protein phosphorylation. Nevertheless, the emergence of resistance, often attributed to cap structure mutations, poses a challenge to imatinib efficacy. Current research endeavours are directed towards overcoming resistance and investigating innovative therapeutic strategies. This article offers a comprehensive analysis of the structural attributes of BCR-ABL, emphasizing its pivotal role as a biomarker and therapeutic target in CML. It underscores the imperative for ongoing research to refine treatment modalities and enhance overall outcomes in managing CML.

Identification of a Panel of miRNAs Associated with Resistance to Palbociclib and Endocrine Therapy

We investigated whether we could identify a panel of miRNAs associated with response to treatment in tumor tissues of patients with Hormone Receptor-positive/HER2-negative metastatic breast cancer treated with endocrine therapy (ET) and the CDK4/6 inhibitor (CDK4/6i)i palbociclib. In total, 52 patients were evaluated, with 41 receiving treatment as the first line. The overall median PFS was 20.8 months (range 2.5-66.6). In total, 23% of patients experienced early progression (<6 months). Seven miRNAs (miR-378e, miR-1233, miR-99b-5p, miR-1260b, miR-448, -miR-1252-5p, miR-324-3p, miR-1233-3p) showed a statistically significant negative association with PFS. When we considered PFS < 6 months, miR-378e, miR-99b-5p, miR-877-5p, miR-1297, miR-455-5p, and miR-4536-5p were statistically associated with a poor outcome. In the multivariate analysis, the first three miRNAs confirmed a significant and independent impact on PFS. The literature data and bioinformatic tools provide an underlying molecular rationale for most of these miRNAs, mainly involving the PI3K/AKT/mTOR pathway and cell-cycle machinery as cyclin D1, CDKN1B, and protein p27Kip1 and autophagy. Our findings propose a novel panel of miRNAs associated with a higher likelihood of early progression in patients treated with ET and Palbociclib and may contribute to shed some light on the mechanisms of de novo resistance to CDK4/6i, but this should be considered exploratory and evaluated in larger cohorts.

A Phase I Study of the CDK4/6 Inhibitor Palbociclib in Combination with Cetuximab and Radiotherapy for Locally Advanced Head and Neck Squamous Cell Carcinoma

PURPOSE

Palbociclib, a cyclin D kinase 4 (CDK4)/6 inhibitor, has shown radiosensitizing effects in preclinical studies. There is a strong rationale for adding palbociclib to cetuximab and radiotherapy in locally advanced head and neck squamous cell carcinoma (LA-HNSCC), especially in p16-negative HNSCC.

PATIENTS AND METHODS

We conducted a phase I dose-escalation study (NCT03024489) using a classical 3+3 design to determine safety, tolerability, and MTD of palbociclib, cetuximab, and intensity-modulated radiotherapy (IMRT) combination. At the recommended phase II dose (RP2D), additional p16-negative patients were enrolled.

RESULTS

Twenty-seven patients with LA-HNSCC (13 in dose escalation, 14 in expansion) with oropharyngeal (41%) and hypopharyngeal (30%) cancers were enrolled. The MTD was not reached, and the RP2D of palbociclib was established at the full standard palbociclib dose of 125 mg/day for 21 days per cycle, administered for two cycles during IMRT. The most common grade 3-4 toxicities were mucositis (59%), radiation dermatitis (22%), and neutropenia (22%), with a febrile neutropenia rate of 7%. Common genomic alterations included mutations in TP53 (57%), GNAQ (35%), and PIK3CA (17%), and copy-number gains in CCND1 (22%), CCND2 (9%), and EGFR (9%). Overall, p16 expression was positive in 15% of patients. No correlation was observed between p16 status, genomic alterations, and preliminary efficacy. The objective response rate was 84%. The rates for 2-year locoregional control, event-free survival, and overall survival were 73%, 48%, and 71%, respectively.

CONCLUSIONS

The palbociclib, cetuximab, and IMRT combination was well tolerated. The RP2D was established, while no MTD was determined. The regimen demonstrated promising preliminary efficacy, suggesting further investigation is warranted in patients with cisplatin-ineligible p16/human papilloma virus-unrelated LA-HNSCC.

A new treatment for breast cancer using a combination of two drugs: AZD9496 and palbociclib

In this study, we examined a mathematical model of breast cancer (BC) treatment that combines an oral oestrogen receptor inhibitor, AZD9496 with Palbociclib, a selective inhibitor of cyclin- dependent kinases CDK4 and CDK6. Treatment is described by analytical functions that enable us to control the dosage and time interval of the treatment, thus personalising the treatment for each patient. Initially, we investigated the effect of each treatment separately, and finally, we investigated the combination of both treatments. By applying numerical simulations, we confirmed that the combination of AZD9496 with palbociclib was the optimal treatment for BC. The dosage of AZD9496 increased and decreased throughout the treatment period, while the intervals were constant between treatments. Palbociclib changed almost cyclically, whereas the time intervals remained constant. To investigate the mathematical model, we applied the singularly perturbed homotopy analysis method, which is a numerical algorithm. The significant advantage of this method is that the mathematical model does not have to contain a small parameter (as is standard in perturbation theory). However, it is possible to artificially introduce a small parameter into the system of equations, making it possible to study the model using asymptotic methods.

Spectroscopic determination of hydrophobic adulterant tadalafil by aptasensor based ellipsometry

Tadalafil is one of the selective phosphodiesterase type 5 inhibitors (PDE5) and serves as the active compound in drugs used for the treatment of erectile dysfunction. These PDE5 inhibitors are prescribed under medical supervision. However, cases of adulteration of dietary supplements with PDE5 inhibitors or their unapproved analogs have been reported worldwide. The presence of the PDE5 inhibitors in such supplements poses a serious health risk to consumers, particularly when combined with certain nitrate-containing drugs, as their toxic effects have not been thoroughly assessed and may result in unpredictable adverse reactions. Therefore, it is crucial to detect adulteration in these dietary supplements. However, current methods for PDE5 inhibitor detection rely on time-consuming and expensive analytical techniques, although they are sensitive. In this study, we propose an aptasensor based on ellipsometry for the detection of PDE5 inhibitors. To enhance the detection specificity for PDE5 inhibitors, we designed an aptamer with a hydrophobic pocket that incorporates a guanine base-rich region and a three-way junction. This design is particularly effective considering the poor aqueous solubility of PDE5 inhibitors. Preliminary results demonstrate that tadalafil detection in various media can be achieved within the range of 1-2000 ng/mL. The limit of detection for the active compound of tadalafil is as low as 1.82 ng/mL.

Recent advances for treatment of upper gastrointestinal malignancy

Recent prospective trials for esophageal cancer, gastric cancer, and gastrointestinal stromal tumor (GIST) are encouraging. This manuscript reviews selected recently published studies. Not surprisingly, immunotherapy dominates the current clinical trial landscape. However, targeted biologic therapies and standard chemotherapy remain critical to the treatment of gastric and esophageal cancer while imatinib remains the backbone for advanced or metastatic GISTs. For all three cancers, surgical resection remains important when intent of treatment is potential cure.

The Role of Ranolazine in Heart Failure-Current Concepts

Heart failure is a complex clinical syndrome with a detrimental impact on mortality and morbidity. Energy substrate utilization and myocardial ion channel regulation have gained research interest especially after the introduction of sodium-glucose co-transporter 2 inhibitors in the treatment of heart failure. Ranolazine or N-(2,6-dimethylphenyl)-2-(4-[2-hydroxy-3-(2-methoxyphenoxy) propyl] piperazin-1-yl) acetamide hydrochloride is an active piperazine derivative which inhibits late sodium current thus minimizing calcium overload in the ischemic cardiomyocytes. Ranolazine also prevents fatty acid oxidation and favors glycose utilization ameliorating the "energy starvation" of the failing heart. Heart failure with preserved ejection fraction is characterized by diastolic impairment; according to the literature ranolazine could be beneficial in the management of increased left ventricular end-diastolic pressure, right ventricular systolic dysfunction and wall shear stress which is reflected by the high natriuretic peptides. Fewer data is evident regarding the effects of ranolazine in heart failure with reduced ejection fraction and mainly support the control of the sodium-calcium exchanger and function of sarcoendoplasmic reticulum calcium adenosine triphosphatase. Ranolazine's therapeutic mechanisms in myocardial ion channels and energy utilization are documented in patients with chronic coronary syndromes. Nevertheless, ranolazine might have a broader effect in the therapy of heart failure and further mechanistic research is required.

Modifying Trial Design May Be Key to Full Sotorasib Approval

Due to design flaws and disappointing progression-free survival data in CodeBreaK 200, a confirmatory phase III trial for the KRASG12C inhibitor sotorasib, the drug's full approval as a second-line option for metastatic KRASG12C non-small cell lung cancer may be delayed and will likely hinge on further studies.

Serum CA125 level as predictors of the efficacy of olaparib maintenance therapy for platinum-sensitive relapsed ovarian cancer

AIM

Ovarian cancer is a gynecological malignancy with a poor prognosis. For platinum-sensitive relapsed ovarian cancer, maintenance therapy with poly-ADP ribose polymerase (PARP) inhibitors after chemotherapy is considered; however, olaparib treatment does not always lead to sufficient progression-free survival (PFS). This study aimed to identify factors that predict the efficacy of maintenance therapy using olaparib in platinum-sensitive relapsed ovarian cancer.

METHODS

Twenty-seven patients with platinum-sensitive relapsed ovarian cancer, who received initial treatment and showed complete or partial response to prior chemotherapy at our hospital, were included. The primary outcome was the time from the end of previous platinum-based chemotherapy to disease progression (PFS). The Kaplan-Meier method was used to generate time-to-event curves for PFS; multivariate analysis was performed using the Cox proportional hazards regression model.

RESULTS

The median PFS was 12 months (95% confidence interval [CI]: 8.3-15.8). Before olaparib administration, the median PFS was 12 months in the <4.1 neutrophil-to-lymphocyte ratio group and 4 months in the ≥4.1 group, with PFS being significantly better in the <4.1 group (log-rank: p = 0.023). When comparing serum cancer antigen 125 (CA125) levels, the median PFS was 13 months in the <18 U/mL group and 6 months in the >18 U/mL group (log-rank: p = 0.022). Multivariate Cox regression analysis revealed that CA125 was the factor affecting PFS (hazard ratio: 4.85; 95% CI: 1.53-15.38).

CONCLUSIONS

Serum CA125 levels at olaparib initiation in patients with platinum-sensitive relapsed ovarian cancer may predict PFS as an effect of maintenance therapy using olaparib to treat recurrent disease.

Neoadjuvant Imatinib in Locally Advanced Gastrointestinal Stromal Tumors (GISTs) is Effective and Safe: Results from a Prospective Single-Center Study with 108 Patients

BACKGROUND

Neoadjuvant imatinib is considered for gastrointestinal stromal tumors (GISTs) when decreased tumor size provides less extensive surgery and higher R0 resection rates. This study evaluates the effectivity and safety of neoadjuvant imatinib for large or locally advanced GIST.

PATIENTS AND METHODS

From the prospective database of the Dutch GIST Consortium, all patients who underwent surgery after neoadjuvant imatinib at our center between 2009 and 2022 were selected. Independent and blinded assessment of surgical strategy was performed by two surgeons, based on anonymized computed tomography (CT) scans before and after neoadjuvant imatinib.

RESULTS

Of 113 patients that received neoadjuvant imatinib, 108 (95%) [mean age 61.6, standard deviation (SD) 11.5, 54% male] underwent a GIST resection. Of all GISTs, 67% was localized in the stomach and 25% in the duodenum or small intestine. In 74% of the patients with GIST, a KIT exon 11 mutation was found. Decreased tumor size was seen in 95 (88%) patients. Having a KIT exon 11 mutation [odds ratio (OR) 5.64, 95% confidence interval (CI) 1.67-19.1, p < 0.01] or not having a mutation (OR 0.19, 95% CI 0.04-0.89, p = 0.04) were positive and negative predictive values for partial response, respectively. In 55 (51%) patients, there was deescalation of surgical strategy after neoadjuvant imatinib. Surgical complications were documented in 16 (15%) patients (n = 8, grade II; n = 5, grade IIIa; n = 3, grade IIIb) and R0 resection was accomplished in 95 (89%) patients. The 5-year disease-free and overall survival were 80% and 91%, respectively.

CONCLUSION

This study shows that neoadjuvant imatinib is effective and safe for patients with large or locally advanced GIST.

Single trajectory treatment response for predominant negative symptoms: Post-hoc analysis of a clinical trial with cariprazine and risperidone

Examining the heterogeneity of negative symptoms of schizophrenia contributes to the identification of available treatment targets. Generally, prior evidence classified three to four symptom treatment response trajectory groups over the course of positive symptoms, yet, no evidence exists regarding the heterogeneity of medium-term response to predominant negative symptoms. The current post-hoc analysis aims to identify the heterogeneity in negative symptom treatment response trajectories among patients with predominant negative symptoms who received either cariprazine or risperidone for 26 weeks. Treatment response was analyzed based on the: the Positive and Negative Syndrome Scale Factor Score for Negative Symptoms (PANSS-FSNS), and the Clinical Global Impression Severity (CGIS) and Improvement (CGII) scales. To identify subgroups of patients with a similar course of treatment response, group-based trajectory modelling was utilized. Results demonstrated that in comparison with competing models, a single trajectory best described the treatment response of patients with predominant negative symptoms. The results indicate that patients with predominant negative symptoms with over ten years of schizophrenia respond rapidly to adequate treatment and follow a course of steady improvement.

Pharmacokinetic boosting of olaparib: A randomised, cross-over study (PROACTIVE-study)

BACKGROUND

Pharmacokinetic (PK) boosting is the intentional use of a drug-drug interaction to enhance systemic drug exposure. PK boosting of olaparib, a CYP3A-substrate, has the potential to reduce PK variability and financial burden. The aim of this study was to investigate equivalence of a boosted, reduced dose of olaparib compared to the non-boosted standard dose.

METHODS

This cross-over, multicentre trial compared olaparib 300 mg twice daily (BID) with olaparib 100 mg BID boosted with the strong CYP3A-inhibitor cobicistat 150 mg BID. Patients were randomised to the standard therapy followed by the boosted therapy, or vice versa. After seven days of each therapy, dense PK sampling was performed for noncompartmental PK analysis. Equivalence was defined as a 90% Confidence Interval (CI) of the geometric mean ratio (GMR) of the boosted versus standard therapy area under the plasma concentration-time curve (AUC0-12 h) within no-effect boundaries. These boundaries were set at 0.57-1.25, based on previous pharmacokinetic studies with olaparib capsules and tablets.

RESULTS

Of 15 included patients, 12 were eligible for PK analysis. The GMR of the AUC0-12 h was 1.45 (90% CI 1.27-1.65). No grade ≥3 adverse events were reported during the study.

CONCLUSIONS

Boosting a 100 mg BID olaparib dose with cobicistat increases olaparib exposure 1.45-fold, compared to the standard dose of 300 mg BID. Equivalence of the boosted olaparib was thus not established. Boosting remains a promising strategy to reduce the olaparib dose as cobicistat increases olaparib exposure Adequate tolerability of the boosted therapy with higher exposure should be established.

Phase II trial of CDK4/6 inhibitor palbociclib in advanced sarcoma based on mRNA expression of CDK4/ CDKN2A

Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors demonstrated activity in terms of progression-free survival (PFS) in advanced dedifferentiated liposarcoma (DD-LPS), a sarcoma with CDK4 amplification. CDK4 overexpression is by far more common than amplification in sarcomas and it might be a rational target for CDK inhibitors. Preclinical investigators of this study found that CDK4 overexpression, while not of CDKN2A, was the most consistent predictive factor for palbociclib efficacy in sarcomas. Advanced adult-type soft-tissue sarcoma, excluding DD-LPS, or bone sarcoma patients, progressing after at least one systemic line, whose tumors overexpressed CDK4, but not CDKN2A at baseline biopsy, were accrued in this single-arm phase II trial (EudraCT number: 2016-004039-19). With the main endpoint of a 6-month PFS rate, 40% was considered promising in this population. Palbociclib was administered orally at 125 mg/day for 21 days in 28-day cycles. A total of 214 patients with 236 CDK4/CDKN2A determinations were assessed for prescreening, archival material (141), and screening, baseline biopsy (95). There were 28 (29%) with favorable mRNA profiles from 95 screened patients at baseline. From 23 enrolled patients, 21 evaluable, the 6-month PFS rate was 29% (95% CI 9-48), and there were 6 patients out of 21 with a PFS longer than 6 months. The median PFS and overall survival were 4.2 (95% CI 3.6-4.8) and 12 (95% CI 8.7-15.4) months, respectively. Translational research showed a significant correlation between CDK4 mRNA and protein expression. Palbociclib was active in a variety of sarcoma subtypes, selected by CDK4/CDKN2A, and deserves further investigation in the sarcoma context.

Eltoprazine modulated gamma oscillations on ameliorating L-dopa-induced dyskinesia in rats

AIM

Parkinson's disease (PD) is a pervasive neurodegenerative disease, and levodopa (L-dopa) is its preferred treatment. The pathophysiological mechanism of levodopa-induced dyskinesia (LID), the most common complication of long-term L-dopa administration, remains obscure. Accumulated evidence suggests that the dopaminergic as well as non-dopaminergic systems contribute to LID development. As a 5-hydroxytryptamine 1A/1B receptor agonist, eltoprazine ameliorates dyskinesia, although little is known about its electrophysiological mechanism. The aim of this study was to investigate the cumulative effects of chronic L-dopa administration and the potential mechanism of eltoprazine's amelioration of dyskinesia at the electrophysiological level in rats.

METHODS

Neural electrophysiological analysis techniques were conducted on the acquired local field potential (LFP) data from primary motor cortex (M1) and dorsolateral striatum (DLS) during different pathological states to obtain the information of power spectrum density, theta-gamma phase-amplitude coupling (PAC), and functional connectivity. Behavior tests and AIMs scoring were performed to verify PD model establishment and evaluate LID severity.

RESULTS

We detected exaggerated gamma activities in the dyskinetic state, with different features and impacts in distinct regions. Gamma oscillations in M1 were narrowband manner, whereas that in DLS had a broadband appearance. Striatal exaggerated theta-gamma PAC in the LID state contributed to broadband gamma oscillation, and aperiodic-corrected cortical beta power correlated robustly with aperiodic-corrected gamma power in M1. M1-DLS coherence and phase-locking values (PLVs) in the gamma band were enhanced following L-dopa administration. Eltoprazine intervention reduced gamma oscillations, theta-gamma PAC in the DLS, and coherence and PLVs in the gamma band to alleviate dyskinesia.

CONCLUSION

Excessive cortical gamma oscillation is a compelling clinical indicator of dyskinesia. The detection of enhanced PAC and functional connectivity of gamma-band oscillation can be used to guide and optimize deep brain stimulation parameters. Eltoprazine has potential clinical application for dyskinesia.

Imatinib plasma levels in patients with gastrointestinal stromal tumour under routine clinical practice conditions

OBJECTIVES

Imatinib is the first therapeutic option for the treatment of unresectable or metastatic gastrointestinal stromal tumours. Previous studies have shown an improvement in patient survival rates following the use of imatinib. Nevertheless, adequate plasma concentrations of imatinib are necessary to achieve such improvement in survival and limit the toxicity of the drug. This study aims to analyse the influence of imatinib plasma concentrations on efficacy and safety in the treatment of gastrointestinal stromal tumour.

MATERIALS AND METHODS

This descriptive, multicentre study analysed plasma levels of imatinib in patients diagnosed with gastrointestinal stromal tumour in the period 2019-2020. An optimal therapeutic range of 750-1500 ng/mL was established for the patient stratification based on their minimum plasma concentrations measured at the steady state.

RESULTS

This study included 11 patients with metastatic disease in total, among whom only 54.5% (n  =  6) had a minimum plasma concentrations measured at the steady state value within the therapeutic range. A median progression-free survival of 7.0 months was recorded for those patients with minimum plasma concentrations measured at the steady state < 750 ng/mL, while that median progression-free survival value remained unachieved for the group with minimum plasma concentrations measured at the steady state > 750 ng/mL (p  =  0.005). The toxicity rate was 25% and 14.3% for patients with minimum plasma concentrations measured at the steady state > 1500 ng/mL and minimum plasma concentrations measured at the steady state ≤1500 ng/mL, respectively (p  =  0.66).

CONCLUSIONS

The present study aims to describe the correlation between the toxicity and effectiveness of imatinib as a function of minimum plasma concentrations measured at the steady state under routine clinical practice conditions. The results described here show the usefulness of imatinib plasma concentrations monitoring as part of the standard daily routine in our hospitals.

Comparison between olanzapine and aripiprazole treatment for 104 weeks after hospital discharge in schizophrenia spectrum disorders: a multicenter retrospective cohort study in a real-world setting

RATIONALE

The long-term effectiveness of olanzapine and aripiprazole in real clinical conditions at flexible doses in patients after hospital discharge has not been evaluated yet.

OBJECTIVES

This study was a multicenter retrospective cohort study. Patients with schizophrenia (n = 398) were prescribed olanzapine (n = 303) or aripiprazole (n = 95) at hospital discharge. The continuation of olanzapine or aripiprazole at 26, 52, or 104 weeks after the hospital discharge were compared using a Cox proportional hazards model and adjusted for possible confounders.

RESULTS

The Kaplan-Meier survival curves revealed that the continuation of olanzapine at 26 (P = 0.001) and 52 weeks (P = 0.018) was significantly higher than that of aripiprazole but not at 104 weeks. Olanzapine was better than aripiprazole in efficacy at 26 (hazard ratio: 0.321, 95% confidence interval: 0.159-0.645, P = 0.001), 52 (hazard ratio: 0.405, 95% confidence interval: 0.209-0.786, P = 0.008), and 104 weeks (hazard ratio: 0.438, 95% confidence interval: 0.246-0.780, P = 0.005). Aripiprazole was better than olanzapine in tolerability at 104 weeks (hazard ratio: 4.574, 95% confidence interval: 1.415-14.787, P = 0.011). Rates after two years continuation of olanzapine and aripiprazole were not significantly different in patients with less than five years' duration of illness, but olanzapine was more commonly maintained for more than two years in those patients who had been ill for over five years' due to its greater efficacy.

CONCLUSION

Olanzapine treatment showed better continuation rates at 26 and 52 after hospital discharge than aripiprazole, whereas maintenance with the two antipsychotics did not differ significantly at 104 weeks, due reduced tolerability of long-term olanzapine treatment.

[Efficacy of Sildenafil oral spray for the treatment of erectile dysfunction in patients with type 2 diabetes mellitus and prediabetes]

AIM

To evaluate the results of using Sildenafil in the form of an oral spray (Gent) for the treatment of erectile dysfunction (ED) in men with type 2 diabetes mellitus (DM) and prediabetes.

MATERIAL AND METHODS

A total of 60 patients were divided into two groups of 30 people. The group 1 included patients with prediabetes, while group 2 consisted of patients with type 2 DM. All men had proven ED. The severity of ED was assessed using the International Index of Erectile Function (IIEF-5). To assess the state of penile blood flow, all patients underwent Doppler ultrasound before and after treatment. Patients with prediabetes used Sildenafil in the form of oral spray (Gent) 25 mg (2 doses) 1 time per day for 1 month, patients with type 2 diabetes received 50 mg (4 injections) every other day for 1 month. In addition, most of the subjects took metformin and followed diet therapy.

RESULTS

In patients of both groups, the administration of Sildenafil oral spray led to a decrease in body weight, waist circumference, a decrease in insulin and Hemoglobin A1C level without changing of hypoglycemic therapy in those with type 2 DM. In men with prediabetes, a decrease in fasting insulin levels was found. During treatment, half of the persons with impaired glucose metabolism had an increase in the testosterone level. According to IIEF-5, a decrease in the severity of ED in both groups of patients was seen. In men with prediabetes, the average IIEF-5 score increased from 15.98 to 21.57 points (p<0.05), while in patients with type 2 DM it improved from 12.18 to 18.44 points (p<0.05). Doppler ultrasound indicated a significant increase in the maximum systolic blood flow velocity and arterial resistivity index after treatment with Sildenafil oral spray in patients with both prediabetes and type 2 diabetes.

CONCLUSION

Sildenafil oral spray can be effectively used for the treatment of ED in men with type 2 DM and prediabetes.

Clinical Considerations for the Integration of Adjuvant Olaparib into Practice for Early Breast Cancer: A Canadian Perspective

With the recent Health Canada approval of olaparib for high-risk, HER2-negative early breast cancer, physicians are now facing the practical challenges of integrating olaparib into current management of triple-negative breast cancer (TNBC) and HR-positive, HER2-negative (HR+/HER2-) early breast cancer. This review provides perspectives on some of the challenges related to identification of olaparib candidates, with a focus on the latest guidance for germline BRCA testing and considerations regarding high-risk disease definitions. Updated treatment pathways are explored for both disease states, including other adjuvant treatment options such as pembrolizumab, capecitabine, and abemaciclib. Gaps in the current literature regarding the sequential or combined use of these adjuvant therapies are noted and future, potentially informative, studies are briefly examined.

Multiple intratumoral sources of kit ligand promote gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and is typically driven by a single mutation in the Kit or PDGFRA receptor. While highly effective, tyrosine kinase inhibitors (TKIs) are not curative. The natural ligand for the Kit receptor is Kit ligand (KitL), which exists in both soluble and membrane-bound forms. While KitL is known to stimulate human GIST cell lines in vitro, we used a genetically engineered mouse model of GIST containing a common human KIT mutation to investigate the intratumoral sources of KitL, importance of KitL during GIST oncogenesis, and contribution of soluble KitL to tumor growth in vivo. We discovered that in addition to tumor cells, endothelia and smooth muscle cells produced KitL in KitV558Δ/+ tumors, even after imatinib therapy. Genetic reduction of total KitL in tumor cells of KitV558Δ/+ mice impaired tumor growth in vivo. Similarly, genetic reduction of tumor cell soluble KitL in KitV558Δ/+ mice decreased tumor size. By RNA sequencing, quantitative PCR, and immunohistochemistry, KitL expression was heterogeneous in human GIST specimens. In particular, PDGFRA-mutant tumors had much higher KitL expression than Kit-mutant tumors, suggesting the benefit of Kit activation in the absence of mutant KIT. Serum KitL was higher in GIST patients with tumors resistant to imatinib and in those with tumors expressing more KitL RNA. Overall, KitL supports the growth of GIST at baseline and after imatinib therapy and remains a potential biomarker and therapeutic target.

Glutamine and amino acid metabolism as a prognostic signature and therapeutic target in endometrial cancer

INTRODUCTION

Endometrial cancer (EC) is the most common female reproductive system cancer in developed countries with growing incidence and associated mortality, which may be due to the growing prevalence of obesity. Metabolism reprogramming including glucose, amino acid, and lipid remodeling is a hallmark of tumors. Glutamine metabolism has been reported to participate in tumor proliferation and development. This study aimed to develop a glutamine metabolism-related prognostic model for EC and explore potential targets for cancer treatment.

METHOD

Transcriptomic data and survival outcome of EC were retrieved from The Cancer Genome Atlas (TCGA). Differentially expressed genes related to glutamine metabolism were recognized and utilized to build a prognostic model by univariate and multivariate Cox regressions. The model was confirmed in the training, testing, and the entire cohort. A nomogram combing prognostic model and clinicopathologic features was established and tested. Moreover, we explored the effect of a key metabolic enzyme, PHGDH, on the biological behavior of EC cell lines and xenograft model.

RESULTS

Five glutamine metabolism-related genes, including PHGDH, OTC, ASRGL1, ASNS, and NR1H4, were involved in prognostic model construction. Kaplan-Meier curve suggested that patients recognized as high risk underwent inferior outcomes. The receiver operating characteristic (ROC) curve showed the model was sufficient to predict survival. Enrichment analysis recognized DNA replication and repair dysfunction in high-risk patients whereas immune relevance analysis revealed low immune scores in the high-risk group. Finally, a nomogram integrating the prognostic model and clinical factors was created and verified. Further, knockdown of PHGDH showed cell growth inhibition, increasing apoptosis, and reduced migration. Promisingly, NCT-503, a PHGDH inhibitor, significantly repressed tumor growth in vivo (p = 0.0002).

CONCLUSION

Our work established and validated a glutamine metabolism-related prognostic model that favorably evaluates the prognosis of EC patients. DNA replication and repair may be the crucial point that linked glutamine metabolism, amino acid metabolism, and EC progression. High-risk patients stratified by the model may not be sufficient for immune therapy. PHGDH might be a crucial target that links serine metabolism, glutamine metabolism as well as EC progression.

Interruption of imatinib in advanced gastrointestinal stromal tumor after prolonged imatinib maintenance in the absence of gross tumor lesions

BACKGROUND

Current guidelines recommend indefinite imatinib treatment for advanced gastrointestinal stromal tumor (GIST) patients. Imatinib-refractory progression-free survival (PFS) and overall survival were previously reported not to differ between GIST patients who interrupted imatinib and those who did not.

METHODS

Clinical outcomes of 77 consecutive patients with recurrent or metastatic GIST who interrupted imatinib treatment after maintaining years of imatinib treatment in the absence of gross tumor lesions were retrospectively analyzed. Associations between clinical factors and progression-free survival (PFS) following imatinib interruption were analyzed.

RESULTS

The median time from the absence of gross tumor lesions to imatinib interruption was 61.5 months. Since imatinib interruption, the median PFS was 19.6 months, and 4 patients (26.3%) remained progression-free for longer than 5 years. Among the patients who had progressive disease following the interruption, imatinib re-introduction led to an 88.6% objective response rate and a 100% disease control rate. Complete removal of the initial gross tumor lesion(s) and complete removal of the residual gross tumor lesion(s) by local treatment (vs. no local treatment or residual lesions after local treatment) were independently associated with favorable PFS.

CONCLUSION

Interruption of imatinib following prolonged maintenance in the absence of gross tumor lesions led to disease progression in the majority of cases. However, re-introduction of imatinib resulted in effective tumor control. Unmaintained remission seems to be possible in some patients with metastatic or recurrent GIST after a prolonged remission with imatinib if there is complete removal of any gross tumor lesions.

False-Negative Testing for FIP1L1::PDGFRA by Fluorescence in situ Hybridization Is a Frequent Cause of Diagnostic Delay

The imatinib-sensitive fusion gene FIP1L1::PDGFRA is the most frequent molecular abnormality identified in patients with eosinophilic myeloid neoplasms. Rapid recognition of this mutation is essential given the poor prognosis of PDGFRA-associated myeloid neoplasms prior to the availability of imatinib therapy. We report a case of a patient in whom delayed diagnosis resulted in cardiac transplantation for eosinophilic endomyocardial fibrosis. The delay in diagnosis was due, in part, to a false-negative result in fluorescence in situ hybridization (FISH) testing for FIP1L1::PDGFRA. To explore this further, we examined our cohort of patients presenting with confirmed or suspected eosinophilic myeloid neoplasms and found 8 additional patients with negative FISH results despite a positive reverse-transcriptase polymerase chain reaction test for FIP1L1::PDGFRA. More importantly, false-negative FISH results delayed the median time to imatinib treatment by 257 days. These data emphasize the importance of empiric imatinib therapy in patients with clinical features suggestive of PDGFRA-associated disease.

Multiple Cerebral Infarctions and Rhabdomyolysis After Sildenafil Citrate (Viagra®) Intoxication: A Case Report

BACKGROUND

Sildenafil citrate (Viagra®) is used to treat male erectile dysfunction; however, little is known about the effects of sildenafil overdose and intoxication. We report a patient who presented with cerebral infarction and rhabdomyolysis after intentional sildenafil intoxication.

CASE REPORT

A 61-year-old man visited the Emergency Department complaining of dysarthria about 1 h after taking more than 30 sildenafil tablets with the intention to commit suicide. Dysarthria and dizziness were observed, but there were no other neurological symptoms. The creatine kinase level was elevated to 3118 U/L, and the patient was diagnosed with rhabdomyolysis. Brain magnetic resonance imaging revealed multiple scattered acute cerebral infarctions in both midbrain artery branches. At 4 h post-intoxication, the dysarthria had improved and we initiated dual antiplatelet therapy for cerebral infarction. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be able to anticipate and treat complications like cerebral infarction and rhabdomyolysis after sildenafil intoxication.

Effects of the second-generation antipsychotic drugs aripiprazole and olanzapine on human adipocyte differentiation

Second-generation antipsychotics (SGAs), used as the cornerstone treatment for schizophrenia and other mental disorders, can cause adverse metabolic effects (e.g. obesity and type 2 diabetes). We investigated the effects of SGAs on adipocyte differentiation and metabolism. The presence of therapeutic concentrations of aripiprazole (ARI) or its active metabolite dehydroaripiprazole (DARI) during human adipocyte differentiation impaired adipocyte glucose uptake while the expression of gene markers of fatty acid oxidation were increased. Additionally, the use of a supra-therapeutic concentration of ARI inhibited adipocyte differentiation. Furthermore, olanzapine (OLA), a highly obesogenic SGA, directly increased leptin gene expression but did not affect adipocyte differentiation and metabolism. These molecular insights are novel, and suggest that ARI, but not OLA, may directly act via alterations in adipocyte differentiation and potentially by causing a switch from glucose to lipid utilization in human adipocytes. Additionally, SGAs may effect crosstalk with other organs, such as the brain, to exert their adverse metabolic effects.

Adagrasib with or without Cetuximab in Colorectal Cancer with Mutated KRAS G12C

BACKGROUND

Adagrasib, an oral small-molecule inhibitor of mutant KRAS G12C protein, has shown clinical activity in pretreated patients with several tumor types, including colorectal cancer. Preclinical studies suggest that combining a KRAS G12C inhibitor with an epidermal growth factor receptor antibody could be an effective clinical strategy.

METHODS

In this phase 1-2, open-label, nonrandomized clinical trial, we assigned heavily pretreated patients with metastatic colorectal cancer with mutant KRAS G12C to receive adagrasib monotherapy (600 mg orally twice daily) or adagrasib (at the same dose) in combination with intravenous cetuximab once a week (with an initial loading dose of 400 mg per square meter of body-surface area, followed by a dose of 250 mg per square meter) or every 2 weeks (with a dose of 500 mg per square meter). The primary end points were objective response (complete or partial response) and safety.

RESULTS

As of June 16, 2022, a total of 44 patients had received adagrasib, and 32 had received combination therapy with adagrasib and cetuximab, with a median follow-up of 20.1 months and 17.5 months, respectively. In the monotherapy group (43 evaluable patients), a response was reported in 19% of the patients (95% confidence interval [CI], 8 to 33). The median response duration was 4.3 months (95% CI, 2.3 to 8.3), and the median progression-free survival was 5.6 months (95% CI, 4.1 to 8.3). In the combination-therapy group (28 evaluable patients), the response was 46% (95% CI, 28 to 66). The median response duration was 7.6 months (95% CI, 5.7 to not estimable), and the median progression-free survival was 6.9 months (95% CI, 5.4 to 8.1). The percentage of grade 3 or 4 treatment-related adverse events was 34% in the monotherapy group and 16% in the combination-therapy group. No grade 5 adverse events were observed.

CONCLUSIONS

Adagrasib had antitumor activity in heavily pretreated patients with metastatic colorectal cancer with mutant KRAS G12C, both as oral monotherapy and in combination with cetuximab. The median response duration was more than 6 months in the combination-therapy group. Reversible adverse events were common in the two groups. (Funded by Mirati Therapeutics; KRYSTAL-1 ClinicalTrials.gov number, NCT03785249.).

Transporting observational study results to a target population of interest using inverse odds of participation weighting

Inverse odds of participation weighting (IOPW) has been proposed to transport clinical trial findings to target populations of interest when the distribution of treatment effect modifiers differs between trial and target populations. We set out to apply IOPW to transport results from an observational study to a target population of interest. We demonstrated the feasibility of this idea with a real-world example using a nationwide electronic health record derived de-identified database from Flatiron Health. First, we conducted an observational study that carefully adjusted for confounding to estimate the treatment effect of fulvestrant plus palbociclib relative to letrozole plus palbociclib as a second-line therapy among estrogen receptor (ER)-positive, human epidermal growth factor receptor (HER2)-negative metastatic breast cancer patients. Second, we transported these findings to the broader cohort of patients who were eligible for a first-line therapy. The interpretation of the findings and validity of such studies, however, rely on the extent that causal inference assumptions are met.

Should We "PROpel" Olaparib Forward for Metastatic Castration-Resistant Prostate Cancer?

Poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors have shown therapeutic success for patients with metastatic castration-resistant prostate cancer (mCRPC) with homologous recombination repair (HRR) deficiency.1,2 Preclinical data suggest that PARP inhibitors may have efficacy in a wider population if combined with androgen receptor inhibition.3,4 One phase 2 trial for late-stage mCRPC supports this notion, finding that olaparib added to abiraterone/prednisone improved radiographic progression-free survival (PFS) versus abiraterone/prednisone alone in a population that was not biomarker preselected.5 However, another trial with abiraterone and veliparib did not show benefit.6.

Dolutegravir in Pregnancy as Compared with Current HIV Regimens in the United States

BACKGROUND

Data on the effectiveness and safety of dolutegravir-based antiretroviral therapy (ART) for human immunodeficiency virus type 1 (HIV-1) infection in pregnancy as compared with other ART regimens commonly used in the United States and Europe, particularly when initiated before conception, are limited.

METHODS

We conducted a study involving pregnancies in persons with HIV-1 infection in the Pediatric HIV/AIDS Cohort Study whose initial ART in pregnancy included dolutegravir, atazanavir-ritonavir, darunavir-ritonavir, oral rilpivirine, raltegravir, or elvitegravir-cobicistat. Viral suppression at delivery and the risks of infants being born preterm, having low birth weight, and being small for gestational age were compared between each non-dolutegravir-based ART regimen and dolutegravir-based ART. Supplementary analyses that included participants in the Swiss Mother and Child HIV Cohort Study were conducted to improve the precision of our results.

RESULTS

Of the pregnancies in the study, 120 were in participants who received dolutegravir, 464 in those who received atazanavir-ritonavir, 185 in those who received darunavir-ritonavir, 243 in those who received rilpivirine, 86 in those who received raltegravir, and 159 in those who received elvitegravir-cobicistat. The median age at conception was 29 years; 51% of the pregnancies were in participants who started ART before conception. Viral suppression was present at delivery in 96.7% of the pregnancies in participants who received dolutegravir; corresponding percentages were 84.0% for atazanavir-ritonavir, 89.2% for raltegravir, and 89.8% for elvitegravir-cobicistat (adjusted risk differences vs. dolutegravir, -13.0 percentage points [95% confidence interval {CI}, -17.0 to -6.1], -17.0 percentage points [95% CI, -27.0 to -2.4], and -7.0 percentage points [95% CI, -13.3 to -0.0], respectively). The observed risks of preterm birth were 13.6 to 17.6%. Adjusted risks of infants being born preterm, having low birth weight, or being small for gestational age did not differ substantially between non-dolutegravir-based ART and dolutegravir. Results of supplementary analyses were similar.

CONCLUSIONS

Atazanavir-ritonavir and raltegravir were associated with less frequent viral suppression at delivery than dolutegravir. No clear differences in adverse birth outcomes were observed with dolutegravir-based ART as compared with non-dolutegravir-based ART, although samples were small. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.).

Editorial: Not the Same as Adults: Vortioxetine in Adolescents With Major Depression

In this issue, readers can review a multisite, double-blind, randomized, controlled trial (DBRCT) of vortioxetine for adolescent major depression (AMD) by Findling et al.1 The investigators deserve credit for this industry-sponsored study's several innovations: initial treatment following current guidelines, efforts to reduce placebo response rates (PRRs), and creation of both placebo- and active-control arms. The Journal deserves our respect for its commitment to highlighting these innovations, despite the trial's negative result. It is essential to perform treatment studies in adolescents, and this study underscores the fallacy of presuming that drugs showing efficacy in adults will be as effective in our patients.

Adagrasib in Non-Small-Cell Lung Cancer Harboring a KRASG12C Mutation

BACKGROUND

Adagrasib, a KRAS^G12C inhibitor, irreversibly and selectively binds KRAS^G12C, locking it in its inactive state. Adagrasib showed clinical activity and had an acceptable adverse-event profile in the phase 1-1b part of the KRYSTAL-1 phase 1-2 study.

METHODS

In a registrational phase 2 cohort, we evaluated adagrasib (600 mg orally twice daily) in patients with KRAS^G12C -mutated non-small-cell lung cancer (NSCLC) previously treated with platinum-based chemotherapy and anti-programmed death 1 or programmed death ligand 1 therapy. The primary end point was objective response assessed by blinded independent central review. Secondary end points included the duration of response, progression-free survival, overall survival, and safety.

RESULTS

As of October 15, 2021, a total of 116 patients with KRAS^G12C -mutated NSCLC had been treated (median follow-up, 12.9 months); 98.3% had previously received both chemotherapy and immunotherapy. Of 112 patients with measurable disease at baseline, 48 (42.9%) had a confirmed objective response. The median duration of response was 8.5 months (95% confidence interval [CI], 6.2 to 13.8), and the median progression-free survival was 6.5 months (95% CI, 4.7 to 8.4). As of January 15, 2022 (median follow-up, 15.6 months), the median overall survival was 12.6 months (95% CI, 9.2 to 19.2). Among 33 patients with previously treated, stable central nervous system metastases, the intracranial confirmed objective response rate was 33.3% (95% CI, 18.0 to 51.8). Treatment-related adverse events occurred in 97.4% of the patients - grade 1 or 2 in 52.6% and grade 3 or higher in 44.8% (including two grade 5 events) - and resulted in drug discontinuation in 6.9% of patients.

CONCLUSIONS

In patients with previously treated KRAS^G12C -mutated NSCLC, adagrasib showed clinical efficacy without new safety signals. (Funded by Mirati Therapeutics; ClinicalTrials.gov number, NCT03785249.).

Week 96 Genotypic and Phenotypic Results of the Fostemsavir Phase 3 BRIGHTE Study in Heavily Treatment-Experienced Adults Living with Multidrug-Resistant HIV-1

In the phase 3 BRIGHTE study in heavily treatment-experienced adults with multidrug-resistant HIV-1, fostemsavir plus optimized background therapy (OBT) resulted in sustained rates of virologic suppression through 96 weeks. HIV-1 RNA <40 copies/mL was achieved in 163/272 (60%) Randomized Cohort (RC) participants (with 1 or 2 remaining approved fully active antiretrovirals) and 37/99 (37%) Non-randomized Cohort (NRC) participants (with 0 fully active antiretrovirals). Here we report genotypic and phenotypic analyses of HIV-1 samples from 63/272 (23%) RC participants and 49/99 (49%) NRC participants who met protocol-defined virologic failure (PDVF) criteria through Week 96. The incidence of PDVF was as expected in this difficult-to-treat patient population and, among RC participants, was comparable regardless of the presence of predefined gp120 amino acid substitutions that potentially influence phenotypic susceptibility to temsavir (S375H/I/M/N/T, M426L, M434I, M475I) or baseline temsavir 50% inhibitory concentration fold change (IC₅₀ FC). The incidence of PDVF was lower among participants with higher overall susceptibility score to newly used antiretrovirals (OSS-new), indicating that OSS-new may be a preferred predictor of virologic outcome in heavily treatment-experienced individuals. Predefined gp120 substitutions, most commonly M426L or S375N, were emergent on treatment in 24/50 (48%) RC and 33/44 (75%) NRC participants with PDVF, with related increases in temsavir IC₅₀ FC. In BRIGHTE, PDVF was not consistently associated with treatment-emergent genotypic or phenotypic changes in susceptibility to temsavir or to antiretrovirals in the initial OBT. Further research will be needed to identify which factors are most likely to contribute to virologic failure in this heavily treatment-experienced population (ClinicalTrials.gov, NCT02362503).

Adagrasib Response Remains Strong in NSCLC

In the phase II KRYSTAL-1 trial, the KRASG12C inhibitor adagrasib yielded an overall response rate of 43% and a disease control rate of 80% in patients with previously treated KRASG12C-mutant non-small cell lung cancer. After a median follow up of 12.9 months, overall survival was 11.7 months. The drug also shrank brain metastases in 33% of patients who had them.

Profiling oncogenic KRAS mutant drugs with a cell-based Lumit p-ERK immunoassay

KRAS is one of the most heavily mutated oncogenes in cancer and targeting mutant KRAS with drugs has proven difficult. However, recent FDA approval of the KRAS G12C selective inhibitor sotorasib (AMG-510), has breathed new life into the drive to develop mutant KRAS inhibitors. In an effort to study RAS inhibitors in cells and identify new compounds that inhibit Ras signaling, western blotting and ELISA assays are commonly used. These traditional immunoassays are tedious, require multiple washing steps, and are not easily adaptable to a high throughput screening (HTS) format. To overcome these limitations, we applied Lumit immunoassay technology to analyze RAS signaling pathway activation and inhibition through the detection of phosphorylated ERK. The assay we developed was used to rank order potencies of allele specific inhibitors within cell lines harboring various activating KRAS mutations. An inhibition profile was obtained indicating various potencies and selectivity of the inhibitors, including MRTX-1133, which was shown to be highly potent against KRAS G12D signaling. MRTX-1133 had approximately 40 and 400 times less inhibitory potency against G12C and G12V mutant KRAS, respectively, while no inhibition of WT KRAS was observed. The potency of PROTAC compound LC-2 targeting selective degradation of KRAS G12C was also tested using the Lumit pERK immunoassay, and a maximal decrease in RAS signaling was achieved. Lumit immunoassays provide a rapid, homogeneous platform for detecting signaling pathway activation and inhibition. Our results demonstrate that this bioluminescent technology can streamline the analysis of signaling pathways of interest, such as RAS-dependent pathways, and be used to identify much needed inhibitors. The results further imply that similar assay designs could be applied to other signaling pathway nodes.

Digital Real-world Data Suggest Patient Preference for Tadalafil over Sildenafil in Patients with Erectile Dysfunction

BACKGROUND

Erectile dysfunction (ED) is a major care problem worldwide. Tadalafil and sildenafil are the two most common phosphodiesterase-5 inhibitors (PDE5is) used to treat ED.

OBJECTIVE

This study aimed to evaluate patient data of a large online prescription platform (OPP), specifically analyzing preference for tadalafil over sildenafil.

DESIGN, SETTING, AND PARTICIPANTS

Data from a prospectively collected German OPP were retrospectively analyzed. This dataset included patients with a history of taking one or both substances (n = 26 821).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

ED patient baseline characteristics were derived from medical questionnaires for PDE5i prescriptions between May 2019 and May 2020. Order behavior was analyzed in patients who ordered both substances over time. We applied Kruskal-Wallis tests, χ² tests, and fisher's exact tests for statistical analysis.

RESULTS AND LIMITATIONS

Baseline characteristics were comparable for both PDE5is in patients with a median age of 49 yr (sildenafil [interquartile range {IQR} 38-57]; tadalafil [IQR 39-56]), a median body mass index (BMI) of 26 kg/m² (sildenafil [IQR 24.54-29.03]; tadalafil [IQR 24.49-28.69]), ED onset time of >12 mo (sildenafil [87%]; tadalafil [88%]), and the presence of morning erections (sildenafil [62%]; tadalafil [61%]). Tadalafil prescriptions increased significantly from 30% (first order) to 80% (last order) in patients who had already tested both drugs. Patients with age ≤40 yr, BMI ≤25 kg/m², and sustained morning erections preferred tadalafil to sildenafil.

CONCLUSIONS

Using database information from an OPP, preference for tadalafil was shown for patients who had tested both PDE5is. This preference was particularly pronounced in patients with age ≤40 yr, BMI ≤25 kg/m², and sustained morning erections. A well-managed OPP can be used for research on more complex health services.

PATIENT SUMMARY

Analysis of large online prescription platforms provide the benefit of identifying young treatment-naïve patients with early-stage disease, which is highlighted by the fact that about two-thirds of our patients analyzed still maintained spontaneous morning erections. Patients who had tested tadalafil once developed preference for this drug.

Mitapivat versus Placebo for Pyruvate Kinase Deficiency

BACKGROUND

Pyruvate kinase deficiency is a rare, hereditary, chronic condition that is associated with hemolytic anemia. In a phase 2 study, mitapivat, an oral, first-in-class activator of erythrocyte pyruvate kinase, increased the hemoglobin level in patients with pyruvate kinase deficiency.

METHODS

In this global, phase 3, randomized, placebo-controlled trial, we evaluated the efficacy and safety of mitapivat in adults with pyruvate kinase deficiency who were not receiving regular red-cell transfusions. The patients were assigned to receive either mitapivat (5 mg twice daily, with potential escalation to 20 or 50 mg twice daily) or placebo for 24 weeks. The primary end point was a hemoglobin response (an increase from baseline of ≥1.5 g per deciliter in the hemoglobin level) that was sustained at two or more scheduled assessments at weeks 16, 20, and 24. Secondary efficacy end points were the average change from baseline in the hemoglobin level, markers of hemolysis and hematopoiesis, and the change from baseline at week 24 in two pyruvate kinase deficiency-specific patient-reported outcome measures.

RESULTS

Sixteen of the 40 patients (40%) in the mitapivat group had a hemoglobin response, as compared with none of the 40 patients in the placebo group (adjusted difference, 39.3 percentage points; 95% confidence interval, 24.1 to 54.6; two-sided P<0.001). Patients who received mitapivat had a greater response than those who received placebo with respect to each secondary end point, including the average change from baseline in the hemoglobin level. The most common adverse events were nausea (in 7 patients [18%] in the mitapivat group and 9 patients [23%] in the placebo group) and headache (in 6 patients [15%] and 13 patients [33%], respectively). Adverse events of grade 3 or higher occurred in 10 patients (25%) who received mitapivat and 5 patients (13%) who received placebo.

CONCLUSIONS

In patients with pyruvate kinase deficiency, mitapivat significantly increased the hemoglobin level, decreased hemolysis, and improved patient-reported outcomes. No new safety signals were identified in the patients who received mitapivat. (Funded by Agios Pharmaceuticals; ACTIVATE ClinicalTrials.gov number, NCT03548220.).

INK4 Tumor Suppressor Proteins Mediate Resistance to CDK4/6 Kinase Inhibitors

Cyclin-dependent kinases 4 and 6 (CDK4/6) represent a major therapeutic vulnerability for breast cancer. The kinases are clinically targeted via ATP competitive inhibitors (CDK4/6i); however, drug resistance commonly emerges over time. To understand CDK4/6i resistance, we surveyed over 1,300 breast cancers and identified several genetic alterations (e.g., FAT1, PTEN, or ARID1A loss) converging on upregulation of CDK6. Mechanistically, we demonstrate CDK6 causes resistance by inducing and binding CDK inhibitor INK4 proteins (e.g., p18^INK4C). In vitro binding and kinase assays together with physical modeling reveal that the p18^INK4C-cyclin D-CDK6 complex occludes CDK4/6i binding while only weakly suppressing ATP binding. Suppression of INK4 expression or its binding to CDK6 restores CDK4/6i sensitivity. To overcome this constraint, we developed bifunctional degraders conjugating palbociclib with E3 ligands. Two resulting lead compounds potently degraded CDK4/6, leading to substantial antitumor effects in vivo, demonstrating the promising therapeutic potential for retargeting CDK4/6 despite CDK4/6i resistance. SIGNIFICANCE: CDK4/6 kinase activation represents a common mechanism by which oncogenic signaling induces proliferation and is potentially targetable by ATP competitive inhibitors. We identify a CDK6-INK4 complex that is resilient to current-generation inhibitors and develop a new strategy for more effective inhibition of CDK4/6 kinases.This article is highlighted in the In This Issue feature, p. 275.