Population pharmacokinetic and covariate analyses of intravenous trastuzumab (Herceptin®), a HER2-targeted monoclonal antibody, in patients with a variety of solid tumors

Evaluation of Innate Immune System, Body Habitus, and Sex on the Pharmacokinetics and Pharmacodynamics of Anetumab Ravtansine in Patients With Cancer

Anetumab ravtansine, like other ADC drugs, has high inter-patient variability in its pharmacokinetic (PK) and pharmacodynamic (PD) outcomes, which raises concerns about whether current dosing regimens are optimal for patients. The objective of this study was to evaluate covariates, especially body habitus and the innate immune system (IIS), which may affect anetumab ravtansine PK and PD as part of two clinical trials in patients with ovarian cancer and mesothelioma. Biomarkers of Fcγ receptors(FcγR) CD64 on IIS cells, total body weight (TBW), body surface area (BSA), and other covariates, such as sex and age, were analyzed for an association with anetumab ravtansine PK. Higher FcγR CD64, TBW, and BSA were associated with higher clearance (CL) of anetumab ravtansine (p < 0.05). However, there was no relationship between TBW or BSA and FcγR CD64. Female patients had a lower anetumab ravtansine CL (0.030 ± 0.007 L/h) compared to male patients (0.042 ± 0.006 L/h) (p < 0.05). In both studies, patients with stable disease (SD) and partial response (PR) had higher anetumab ravtansine AUC0-inf compared to patients with progressive disease (PD). Individualizing the dose of anetumab ravtansine and potentially other ADCs based only on TBW is not optimal, whereas precision dosing of an ADC based on the inclusion of novel metrics of IIS biomarkers, body habitus, and sex may be more appropriate to reduce variability in PK exposure, reduce toxicity, and improve response.

A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

Cross validation of pharmacokinetic bioanalytical methods: Experimental and statistical design

Pharmacokinetic (PK) analysis is an integral part of drug development. Health agency guidance provides development and validation recommendations for PK bioanalytical methods run in one laboratory. However, as a drug development program progresses, a PK bioanalytical method may need to be run in more than one laboratory. Additionally, a PK bioanalytical method format may change and a new method platform may be validated and implemented during the drug development cycle. Here we describe the cross validation strategy for comparisons of two validated bioanalytical methods used to generate PK data within the same study or across different studies. Current guidance for cross validations is limited and, therefore, Genentech, Inc. has developed a cross validation experimental strategy that utilizes incurred samples along with a comprehensive statistical analysis. One hundred incurred study samples over the applicable range of concentrations are selected based on four quartiles (Q) of in-study concentration levels. The samples are assayed once in the two bioanalytical methods. Bioanalytical method equivalency is assessed for the 100 samples based on pre-specified acceptability criterion: the two methods are considered equivalent if the percent differences in the lower and upper bound limits of the 90 % confidence interval (CI) are both within ±30 %. Quartile by concentration analysis using the same criterion may also need to be performed. A Bland-Altman plot of the percent difference of sample concentrations versus the mean concentration of each sample is also created to help further characterize the data. This strategy is a robust assessment of PK bioanalytical method equivalency and includes subgroup analyses by concentration to assess for biases. This strategy was implemented in two case studies: 1) two different laboratories using the same bioanalytical method and 2) a bioanalytical method platform change from enzyme-linked immunosorbent assay (ELISA) to multiplexing immunoaffinity (IA) liquid chromatography tandem mass spectrometry (IA LC-MS/MS).

Sex differences in the pharmacokinetics of anticancer drugs: a systematic review

BACKGROUND

In addition to the effect of body weight, a patient's sex can influence the pharmacokinetics (PK) of anticancer agents, and thereby their activity and safety. The magnitude and relevance of sex differences, however, are currently unclear.

METHODS

We carried out a systematic review of published studies (clinical, n ≥ 10) on Food and Drug Administration (FDA)-approved (on 31 January 2022) anticancer drugs (excluding hormonal agents), aiming to identify significant PK differences between male and female patients. A difference of ≥20% on PK parameters (clearance or trough concentration) was considered significant. The methodological quality was assessed using the National Institutes of Health study quality assessment tool. This systematic review was conducted according to the PRISMA2020 guidelines and a previously published protocol, which was registered in the PROSPERO database (number 291008).

RESULTS

Data on 99 anticancer agents (for a total of 1643 abstracts and European Medicines Agency/FDA documents) were screened. The final dataset included 112 articles and 8 European Medicines Agency/FDA documents. The median size of a study cohort was 445 patients (range: 12-6468 patients). Significant PK differences (>+20% in clearance or apparent clearance in women) were identified for 14 drugs, and potentially significant PK differences (due to conflicting reports) for another 8 drugs. None of the studies included sex-based summaries to assess whether the observed differences in PK may impact the efficacy or safety profile.

CONCLUSIONS

Significant sex differences in PK have been identified including commonly used drugs of different classes, such as 5-fluorouracil, doxorubicin, paclitaxel, regorafenib, atezolizumab, and temozolomide. The risk-benefit ratio for such anticancer drugs is likely to be improved by the development of sex-specific dosing strategies. Additional sex-based PK-pharmacodynamic analyses are recommended during dose optimisation and are to be conducted in line with the FDA Project Optimus guidance. They should be reported even if no association between the patients' sex and the activity and/or toxicity of an anticancer drug has been identified.

HDAC6 as a Prognostic Factor and Druggable Target in HER2-Positive Breast Cancer

BACKGROUND

Adjuvant trastuzumab is the standard of care for HER2+ breast cancer (BC) patients. However, >50% of patients become resistant. This study aimed at the identification of the molecular factors associated with disease relapse and their further investigation as therapeutically exploitable targets.

METHODS

Analyses were conducted on formalin-fixed paraffin-embedded tissues of the primary tumors of relapsed (cases) and not relapsed (controls) HER2+ BC patients treated with adjuvant trastuzumab. The nCounter Human Breast Cancer Panel 360 was used. Logistic regression and partitioning around medoids were employed to identify the genes associated with disease recurrence. Cytotoxicity experiments using trastuzumab-resistant cell lines and a network pharmacology approach were carried out to investigate drug efficacy.

RESULTS

A total of 52 patients (26 relapsed and 26 not relapsed) were analyzed. We found that a higher expression of HDAC6 was significantly associated with an increased risk of recurrence, with an adjusted OR of 3.20 (95% CI 1.38-9.91, p = 0.016). Then, we investigated the cytotoxic activity of the selective HDAC6 inhibitor Nexturastat A (NextA) on HER2+ cell lines, which were both sensitive and trastuzumab-resistant. A sub-cytotoxic concentration of NextA, combined with trastuzumab, showed a synergistic effect on BC cell lines. Finally, using a network pharmacology approach, we identified HSP90AA1 as the putative molecular candidate responsible for the synergism observed in vitro.

CONCLUSIONS

Our findings encourage the exploration of the role of HDAC6 as a prognostic factor and the combinatorial use of HDAC6 selective inhibitors combined with trastuzumab in HER2+ BC, in particular for those patients experiencing drug resistance.

Pharmacokinetics of trastuzumab and its efficacy and safety in HER2-positive cancer patients

Trastuzumab is a potent targeted therapy drug for HER2-positive cancer patients. A comprehensive understanding of trastuzumab's mechanism of action, pharmacokinetic (PK) parameters, and steady-state exposure in different treatment regimens and administration routes is essential for a thorough evaluation of the drug's safety and effectiveness. Due to the distinctive pharmacokinetics, indications, and administration methods of trastuzumab, this understanding becomes crucial. Drug exposure can be assessed by measuring trastuzumab's peak concentration, trough concentration, or area under the curve through assays like enzyme-linked immunosorbent assay (ELISA) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). The dose-response (D-R) and exposure-response (E-R) relationships establish the correlation between drug dosage/exposure and the therapeutic effect and safety. Additionally, various covariates such as body weight, aspartate transaminase, and albumin levels can influence drug exposure. This review provides a comprehensive overview of trastuzumab's mechanism of action, data on steady-state concentration and PK parameters under multiple administration routes and indications, discussions on factors influencing PK parameters, and evaluations of the effectiveness and safety of E-R and D-R in diverse HER2-positive cancer patients.

A Phase I Clinical Study Comparing the Pharmacokinetics, Safety, and Immunogenicity of GB221 Injection and Trastuzumab (Herceptin®) in Healthy Chinese Adults

BACKGROUND AND OBJECTIVE

GB221 is a recombinant humanized anti-HER2 monoclonal antibody. The purpose of this study was to evaluate the pharmacokinetic, safety, and immunogenicity of GB221 in healthy Chinese adults in comparison to trastuzumab (Herceptin®).

METHODS

In this randomized, double-blind, parallel-group phase I clinical trial, 88 subjects were randomized 1:1 to receive a single intravenous infusion (90-100 min) of GB221 or trastuzumab (6 mg/kg). The primary pharmacokinetic parameters-maximum observed serum concentration (Cmax), area under the serum concentration-time curve from zero to the last quantifiable concentration at time t (AUC0-t), and area under the serum concentration-time curve from time zero to infinity (AUC0-∞)-of GB221 and trastuzumab were compared to establish whether the 90% confidence interval (CI) attained the 80-125% bioequivalence standard. Safety and immunogenicity were also evaluated.

RESULTS

The GB221 group (n = 43) and the trastuzumab group (n = 44) showed similar pharmacokinetic characteristics. The geometric mean ratios (90% CI) of Cmax, AUC0-t, and AUC0-∞ between the two groups were 107.53% (102.25-113.07%), 108.31% (103.57-113.26%), and 108.34% (103.57-113.33%), respectively. The incidence of treatment-emergent adverse events (TEAEs) was 83.7% (36/43) of the subjects in the GB221 group and 95.5% (42/44) of the subjects in the trastuzumab group. No subjects withdrew from the trial due to TEAEs, and there were no occurrences of serious adverse events. All subjects tested negative for antidrug antibodies (ADA).

CONCLUSION

GB221 demonstrated similar pharmacokinetics to trastuzumab and comparable safety and immunogenicity in healthy Chinese adults.

Does Aggregation of Therapeutic IgGs in PBS Offer a True Picture of What Happens in Models Derived from Human Body Fluids?

Therapeutic proteins such as monoclonal antibodies (mAb) are known to form aggregates due to various factors. Phosphate buffered saline (PBS), human serum, and human serum filtrate (HSF) are some of the models used to analyze mAb stability in physiologically relevant in-vitro conditions. In this study, aggregation of mAb in PBS and models derived from body fluids seeded with mAb samples subjected to various stresses were compared. Samples containing mAb subjected to pH, temperature, UV light, stirring, and interfacial agitation stress were seeded into different models for 2 case studies. In the first case study, %HMW (high molecular weight species) of mAb in PBS and HSF were compared using size exclusion chromatography. It was found that change in %HMW was higher in PBS compared to HSF. For example, PBS containing mAb that was subjected to UV light stress showed change in HMW by >10 % over 72 h, but the change was <5 % in HSF. In second case study, aggregates particles of FITC tagged mAb were monitored in PBS and serum using fluorescence microscope image processing. It was found that PBS and serum containing mAb subjected to stirring and interfacial agitation resulted in aggregates of >2 µm size, and average size and percentage number of particles having >10 µm size was higher in serum compared to PBS at all analysis time point. Overall, it was found that aggregation of mAb in PBS was different from that in human body fluids. Second case study also showed the importance of advanced strategies for further characterization of mAb in serum.

Machine learning-based model constructed from ultrasound radiomics and clinical features for predicting HER2 status in breast cancer patients with indeterminate (2+) immunohistochemical results

BACKGROUND

We aimed to predict human epidermal growth factor receptor 2 (HER2) 2+ status in patients with breast cancer by constructing and validating machine learning models utilizing ultrasound (US) radiomics and clinical features.

METHODS

We analyzed 203 breast cancer cases immunohistochemically determined as HER2 2+ and used fluorescence in situ hybridization (FISH) as the confirmation method. From each case, the study analyzed 840 extracted radiomics features and 11 clinicopathologic features. Cases were randomly split into training (n = 141) and validation sets (n = 62) at a 7:3 ratio. Univariate logistic regression analysis was first performed on the 11 clinicopathologic characteristics. The least absolute shrinkage and selection operator (LASSO) and decision tree (DT) techniques were employed for post-feature selection. Finally, 19 radiomics features were utilized in logistic regression (LR) and Naive Bayesian (NB) classifiers. Model performance was gauged using the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity.

RESULTS

Our models exhibited notable diagnostic efficacy in differentiating HER2-positive from negative breast cancer cases. In the validation sets, the LR model outperformed the NB model with an AUC of 0.860 and accuracy of 83.8% compared to NB's AUC of 0.684 and accuracy of 79.0%. The LR model demonstrated higher sensitivity (92.3% vs. 46.2%) while the NB model had a better specificity (91.8% vs. 63.3%) in the validation set.

CONCLUSIONS

Machine learning models grounded on radiomics efficiently predicted IHC HER2 2+ status in breast cancer patients, suggesting potential enhancements in clinical decision-making for treatment and management.

Effect of Obesity on the Pharmacokinetics and Pharmacodynamics of Anticancer Agents

An objective of the Precision Medicine Initiative, launched in 2015 by the US Food and Drug Administration and National Institutes of Health, is to optimize and individualize dosing of drugs, especially anticancer agents, with high pharmacokinetic and pharmacodynamic variability. The American Society of Clinical Oncology recently reported that 40% of obese patients receive insufficient chemotherapy doses and exposures, which may lead to reduced efficacy, and recommended pharmacokinetic studies to guide appropriate dosing in these patients. These issues will only increase in importance as the incidence of obesity in the population increases. This publication reviews the effects of obesity on (1) tumor biology, development of cancer, and antitumor response; (2) pharmacokinetics and pharmacodynamics of small-molecule anticancer drugs; and (3) pharmacokinetics and pharmacodynamics of complex anticancer drugs, such as carrier-mediated agents and biologics. These topics are not only important from a scientific research perspective but also from a drug development and regulator perspective. Thus, it is important to evaluate the effects of obesity on the pharmacokinetics and pharmacodynamics of anticancer agents in all categories of body habitus and especially in patients who are obese and morbidly obese. As the effects of obesity on the pharmacokinetics and pharmacodynamics of anticancer agents may be highly variable across drug types, the optimal dosing metric and algorithm for difference classes of drugs may be widely different. Thus, studies are needed to evaluate current and novel metrics and methods for measuring body habitus as related to optimizing the dose and reducing pharmacokinetic and pharmacodynamic variability of anticancer agents in patients who are obese and morbidly obese.

A Minimal PBPK Model for Plasma and Cerebrospinal Fluid Pharmacokinetics of Trastuzumab after Intracerebroventricular Administration in Patients with HER2-Positive Brain Metastatic Localizations

BACKGROUND

Dosing regimens of trastuzumab administered by intracerebroventricular (icv) route to patients with HER2-positive brain localizations remain empirical. The objectives of this study were to describe pharmacokinetics (PK) of trastuzumab in human plasma and cerebrospinal fluid (CSF) after simultaneous icv and intravenous (iv) administration using a minimal physiologically-based pharmacokinetic model (mPBPK) and to perform simulations of alternative dosing regimens to achieve therapeutic concentrations in CSF.

METHODS

Plasma and CSF PK data were collected in two patients with HER2-positive brain localizations. A mPBPK model for mAbs consisting of four compartments (tight and leaky tissues, plasma and lymph) was enriched by an additional compartment for ventricular CSF. The comparison between observed and model-predicted concentrations was evaluated using prediction error (PE).

RESULTS

The developed mPBPK model described plasma and CSF trastuzumab concentrations reasonably well with mean PE for plasma and CSF data of 41.8% [interquartile range, IQR = -9.48; 40.6] and 18.3% [-36.7; 60.6], respectively, for patient 1 and 11.4% [-10.8; 28.7] and 22.5% [-27.7; 77.9], respectively, for patient 2. Trastuzumab showed fast clearance from CSF to plasma with Cmin,ss of 0.56 and 0.85 mg/L for 100 and 150 mg q1wk, respectively. Repeated dosing of 100 and 150 mg q3day resulted in Cmin,ss of 10.3 and 15.4 mg/L, respectively. Trastuzumab CSF target concentrations are achieved rapidly and maintained above 60 mg/L from 7 days after a continuous perfusion at 1.0 mg/h.

CONCLUSION

Continuous icv infusion of trastuzumab at 1.0 mg/h could be an alternative dosing regimen to rapidly achieve intraventricular CSF therapeutic concentrations.

Trastuzumab Deruxtecan Dosing in Human Epidermal Growth Factor Receptor 2-Positive Gastric Cancer: Population Pharmacokinetic Modeling and Exposure-Response Analysis

This study evaluated the benefit/risk of trastuzumab deruxtecan (T-DXd) 6.4 mg/kg in patients with human epidermal growth factor receptor 2 (HER2)-positive gastric cancer using pharmacometrics. A population pharmacokinetic (PopPK) model was developed using data from patients with gastric cancer, breast cancer, or other tumors in T-DXd clinical trials, primarily conducted in Asia. Post hoc model-estimated pharmacokinetic metrics were used in exposure-efficacy (objective response rates, ORRs) and exposure-safety analyses. The PopPK analysis included 808 patients (217 with gastric cancer, 512 with breast cancer, and 79 with other cancers). In gastric cancer, the T-DXd 6.4 mg/kg steady-state exposure metrics were lower compared with 6.4 mg/kg in breast cancer, but were similar to 5.4 mg/kg in breast cancer. Tumor type was selected as a significant covariate on T-DXd clearance. In exposure-efficacy analysis among 160 patients with gastric cancer, the T-DXd steady-state minimum concentration was associated with a confirmed ORR in univariate logistic regression analysis (P = .023). The model-predicted confirmed ORRs in gastric cancer were 36.0% (90%CI 29.3% to 43.7%) with 5.4 mg/kg and 40.0% (90%CI 33.1% to 47.6%) with 6.4 mg/kg. Among 808 patients in the exposure-safety analyses, the model-predicted estimates for the rates of any-grade interstitial lung disease (ILD) over a period of 180 days were 10.2% (90%CI 8.7% to 12.8%) with 6.4 mg/kg in gastric cancer and 9.7% (90%CI 8.2% to 11.8%) with 5.4 mg/kg in breast cancer. In gastric cancer, the efficacy of T-DXd was higher at 6.4 mg/kg than at 5.4 mg/kg. Exposure and ILD rates were comparable between 6.4 mg/kg in gastric cancer and 5.4 mg/kg in breast cancer. This study identified T-DXd 6.4 mg/kg as the recommended dose in HER2-positive gastric cancer.

Alternative Trastuzumab Dosing Schedules Are Associated With Reductions in Health Care Greenhouse Gas Emissions

PURPOSE

Cancer care-related greenhouse gas (GHG) emissions harm human health. Many cancer drugs are administered at greater-than-necessary doses, frequencies, and durations. Alternative dosing strategies may enable reductions in cancer care GHG emissions without compromising patient outcomes.

MATERIALS AND METHODS

We used streamlined life-cycle analysis in a case-control simulation to estimate the relative reductions in GHG emissions that would be expected to result from using each of three alternative dosing strategies of trastuzumab (6-month adjuvant treatment duration, once every 4-week dosing, and both) in human epidermal growth factor receptor 2 (HER2)+ breast cancer. Using primary data and conversion factors from the environmental science literature, we estimated per-patient relative reduction in GHG emissions and, using SEER data, health impacts (in terms of disability-adjusted life-years [DALYs] and excess mortality per kg CO2) on bystanders for each alternative dosing strategy.

RESULTS

Compared with the trastuzumab dosing strategy commonly used at baseline (12-month duration of adjuvant therapy and once every 3-week dosing in all settings), adoption of both 6-month adjuvant trastuzumab and once every 4-week trastuzumab dosing would reduce GHG emissions by 4.5%, 18.7%, and 14.6% in the neoadjuvant, adjuvant, and metastatic settings, respectively. We estimate that US-based adoption of alternative trastuzumab dosing would reduce annual DALYs and excess lives lost due to environmental impact of US-based trastuzumab therapy for HER2+ breast cancer by 1.5 and 0.9, respectively.

CONCLUSION

Alternative dosing strategies may materially reduce the population health impacts of cancer care by reducing environmental impact. Regulatory decision making and health technology assessments should consider a treatment's environmental and population health impacts. Clinical trials of alternative dosing strategies are justified on the basis of environmental and population health impacts.

HLX22, an anti-HER-2 monoclonal antibody, in patients with advanced solid tumors overexpressing human epidermal growth factor receptor 2: an open-label, dose-escalation, phase 1 trial

HLX22 is a novel monoclonal antibody targeting human epidermal growth factor receptor 2 (HER2). This first-in-human, phase 1 dose-escalation study aimed to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of HLX22 in patients with advanced solid tumors who had failed or were intolerant to standard therapies. Enrolled patients aged 18 to 75 years with histologically confirmed HER2-overexpressing advanced or metastatic solid tumors received intravenous HLX22 once every 3 weeks at 3, 10, and 25 mg/kg. Primary endpoints were safety and the maximum tolerated dose (MTD). Secondary endpoints included pharmacokinetics, pharmacodynamics, immunogenicity, and efficacy. Between July 31, 2019, and December 27, 2021, 11 patients were enrolled to receive HLX22 at 3 (n = 5), 10 (n = 3), and 25 (n = 3) mg/kg doses. The most common treatment-emergent adverse events were lymphocyte count decreased (45.5%), white blood cell count decreased (36.4%), and hypokalemia (36.4%). No serious adverse events or dose-limiting toxicities occurred during the treatment period, and the MTD was determined at 25 mg/kg once every 3 weeks. Systemic exposure of HLX22 increased with escalating dose levels. No patients achieved a complete or partial response, and four (36.4%) had stable disease. The disease control rate and median progression-free survival were 36.4% (95% confidence interval [CI], 7.9-64.8) and 44.0 days (95% CI, 41.0-170.0), respectively. HLX22 was well tolerated in patients with advanced solid tumors overexpressing HER2 after failure of standard therapies. The study results support further investigation of HLX22 in combination with trastuzumab and chemotherapy.

A phase I/II study of intrathecal trastuzumab in human epidermal growth factor receptor 2-positive (HER2-positive) cancer with leptomeningeal metastases: Safety, efficacy, and cerebrospinal fluid pharmacokinetics

BACKGROUND

Patients with human epidermal growth factor receptor 2-positive (HER2-positive) cancers have a high incidence of central nervous system (CNS) spread, but unfortunately systemic trastuzumab which targets the HER2 receptor has little CNS penetration. The purpose of this study was to determine the maximum-tolerated dose of intrathecal trastuzumab and its efficacy in patients with HER2-positive leptomeningeal disease (LMD).

METHODS

This multicenter study enrolled 34 LMD patients in a combined phase I/II study in treating patients with intrathecal trastuzumab. Any HER2-positive histology was allowed in the phase I; the phase II was limited to HER2-positive breast cancer.

RESULTS

Intrathecal trastuzumab was well-tolerated, with one dose limiting toxicity of grade 4 (arachnoiditis) occurring at the 80 mg twice weekly dose. The recommended phase II dose was 80 mg intrathecally twice weekly. Twenty-six patients at dose level 80 mg were included in evaluation for efficacy: partial response was seen in 5 (19.2%) patients, stable disease was observed in 13 (50.0%), and 8 (30.8%) of the patients had progressive disease. Median overall survival (OS) for phase II dose treated patients was 8.3 months (95% CI 5.2-19.6). The phase II HER2-positive breast cancer patients median OS was 10.5 months (95% CI 5.2-20.9). Pharmacokinetic (PK) studies were limited in the setting of concurrent systemic trastuzumab administration, however, did show stable cerebrospinal fluid (CSF) concentrations with repeated dosing suggest that trastuzumab does not accumulate in the CSF in toxic concentrations.

CONCLUSION

This study suggests promise for potentially improved outcomes of HER-positive LMD patients when treated with intrathecal trastuzumab while remaining safe and well-tolerated for patients.

Early change in the clearance of pembrolizumab reflects the survival and therapeutic response: A population pharmacokinetic analysis in real-world non-small cell lung cancer patients

OBJECTIVES

The dosing pattern of pembrolizumab is based on population pharmacokinetic (Pop-PK) analysis of clinical trials. Data for Japanese patients or patient populations with poor conditions such as cachexia are scarce. In this study, we performed a Pop-PK analysis of Japanese non-small cell lung cancer patients and analyzed the relationship between exposure, treatment effect, and survival.

MATERIALS AND METHODS

A total of 270 blood samples from 76 patients who received 200 mg pembrolizumab every 3 weeks between March 2017 and December 2018 were included. Blood concentrations of pembrolizumab were measured using mass spectrometry, and Pop-PK analysis was conducted using the Phoenix NLME software with a one-compartment model.

RESULTS

The estimated median of clearance (CL) in this analysis population was 0.104 L/day, about half of the historical data for Western data. Overall, pembrolizumab CL decreased over time, with some populations showing increased CL early in the treatment and others showing decreased CL over time. When the time-varying CL was stratified by quartile, the group with decreasing CL showed significantly better treatment response and survival than the group with increasing CL, even though the group included more patients with cachexia. Detailed analysis suggested that the patient population that responded to pembrolizumab treatment had an improved general condition and reduced protein catabolism, further decreasing CL.

CONCLUSION

In populations that benefit from pembrolizumab treatment, CL may be reduced early in their treatment, which may be a predictive and prognostic factor. However, further prospective validation of our findings is needed.

Alternative trastuzumab dosing strategies in HER2-positive early breast cancer are associated with patient out-of-pocket savings

Patients with breast cancer frequently experience financial hardship, often due to the high costs of anti-cancer drugs. We sought to develop alternative trastuzumab dosing strategies, compare their pharmacokinetic effectiveness to standard dosing, and assess the expected financial implications of transitioning to them. We extracted clinical data from the records of 135 retrospectively identified patients with HER2-positive early breast cancer at a single, urban comprehensive cancer center who were treated with trastuzumab between 2017 and 2019. We performed pharmacokinetic simulations on a range of trastuzumab dose levels and frequencies, assessing efficacy by trough trastuzumab concentration (Ctrough) and population and individual likelihoods of Ctrough exceeding trastuzumab minimum effective concentration (MEC). We performed deterministic financial modeling to estimate the treatment-associated financial savings from alternative dosing strategies. Trastuzumab maintenance doses of 4 mg/kg every 3 weeks (Q3W) and 6 mg/kg every 4 weeks (Q4W) had nearly identical probabilities of Ctrough being above MEC as standard of care 6 mg/kg every 3 weeks. In the primary financial analysis, both trastuzumab 4 mg/kg Q3W and 6 mg/kg Q4W were associated with significant drug- and administration-related out-of-pocket cost savings over the duration of therapy, ranging from $765 (neoadjuvant, Q4W) to $2791 (adjuvant, Q4W). In particular, Q4W trastuzumab increased savings related to lost wages and travel cost avoidance. Low-dose and reduced frequency trastuzumab in appropriately selected patients may significantly reduce total drug utilization and meaningfully reduce patient financial toxicity. Prospective clinical trials evaluating low-dose or reduced-frequency administration of therapeutic monoclonal antibodies are warranted and needed.

Predicting HER2 Status in Breast Cancer on Ultrasound Images Using Deep Learning Method

Purpose

The expression of human epidermal growth factor receptor 2 (HER2) in breast cancer is critical in the treatment with targeted therapy. A 3-block-DenseNet-based deep learning model was developed to predict the expression of HER2 in breast cancer by ultrasound images.

Methods

The data from 144 breast cancer patients with preoperative ultrasound images and clinical information were retrospectively collected from the Shandong Province Tumor Hospital. An end-to-end 3-block-DenseNet deep learning classifier was built to predict the expression of human epidermal growth factor receptor 2 by ultrasound images. The patients were randomly divided into a training (n = 108) and a validation set (n = 36).

Results

Our proposed deep learning model achieved an encouraging predictive performance in the training set (accuracy = 85.79%, AUC = 0.87) and the validation set (accuracy = 80.56%, AUC = 0.84). The effectiveness of our model significantly exceeded the clinical model and the radiomics model. The score of the proposed model showed significant differences between HER2-positive and -negative expression (p < 0.001).

Conclusions

These results demonstrate that ultrasound images are predictive of HER2 expression through a deep learning classifier. Our method provides a non-invasive, simple, and feasible method for the prediction of HER2 expression without the manual delineation of the regions of interest (ROI). The performance of our deep learning model significantly exceeded the traditional texture analysis based on the radiomics model.

Impact of Dose Delays and Alternative Dosing Regimens on Pertuzumab Pharmacokinetics

PERJETA (pertuzumab), administered with Herceptin (trastuzumab), is used in the treatment of human epidermal growth factor receptor 2-positive breast cancer. Pertuzumab is currently approved with an initial loading dose of 840 mg, followed by a 420-mg maintenance dose intravenously every 3 weeks. A reloading dose is required if there is a ≥6-week delay in treatment. In response to the potential treatment disruption due to COVID-19, the impact of dose delays and alternative dosing regimens on intravenous pertuzumab for human epidermal growth factor receptor 2-positive breast cancer treatment is presented. Simulations were conducted by using the validated population pharmacokinetic model for pertuzumab, and included (1) 4-, 6-, and 9-week dose delays of the 840 mg/420 mg every 3 weeks dosing regimen and (2) 840 mg/420 mg every 4 weeks and 840 mg every 6 weeks alternative dosing regimens. Simulations were compared with the currently approved pertuzumab dosing regimen. The simulations in 1000 virtual patients showed that a dose reload (840 mg) is required following a dose delay of ≥6 weeks to maintain comparable Ctrough (lowest concentration before the next dose is given) levels to clinical trials. The 840 mg/420 mg every 4 weeks and 840 mg every 6 weeks alternative dosing regimens decrease median steady-state Ctrough by ≈40% compared with the approved regimen, and <90% of patients will be above the target Ctrough . Thus, the alternative 840 mg/420 mg every 4 weeks and 840 mg every 6 weeks pertuzumab dosing regimens are not recommended. Flexibility for intravenous PERJETA-based regimens is available with an alternative route of pertuzumab administration (subcutaneous vs intravenous).

Population pharmacokinetics and exposure-response relationship of trastuzumab and bevacizumab in early-stage breast cancer

AIMS

To describe the sources of interindividual variability of bevacizumab and trastuzumab pharmacokinetics in early-stage breast cancer, and to study the relationship between exposure and both early clinical response and specific adverse events.

PATIENTS AND METHODS

Patients (n = 86) received 6 cycles of docetaxel + trastuzumab. Early tumour response was assessed by determination of the maximum standard uptake value (SUV_max) variation (ΔSUV_max) after 1 cycle using [¹⁸F]-fluorodeoxyglucose (FDG) PET. Early poor responders (ΔSUV_max < 70%) also received bevacizumab from cycle 3 to cycle 6. Sources of interindividual variability in pharmacokinetics of both antibodies were studied by population compartment modelling. Exposure as assessed by area under the concentration-versus-time curve (AUC) was compared between responders and non-responders and between patients experiencing specific adverse events or not.

RESULTS

A two-compartment model described the pharmacokinetics of both antibodies satisfactorily. Their central volume of distributions (Vc) increased with body surface area and their elimination half-lives were shorter (~14 days) than previously reported (~26-28 days). There was a time-dependent increase in trastuzumab Vc, positively correlated to baseline SUV_max. Bevacizumab elimination rate (k₁₀) was positively correlated with ΔSUV_max measured at the end of the first cycle. Bevacizumab had no significantly influence on trastuzumab pharmacokinetics. No relationship between exposure and clinical response or occurrence of adverse events was found.

CONCLUSION

Tumour uptake as assessed by SUV_max influences the pharmacokinetics of bevacizumab and trastuzumab. In early-stage breast cancer, elimination half-lives of these therapeutic monoclonal antibodies may be shorter than those previously reported in more advanced disease.

Is weight-based IV dosing of trastuzumab preferable to SC fixed-dose in some patients? A systematic scoping review

Trastuzumab, a key treatment for HER2-positive breast cancer, is available in weight-based IV and fixed-dose (600 mg) SC formulations. While the Phase 3 HannaH trial indicated non-inferiority of the SC formulation, there is some concern that the target plasma concentration may not be reached in overweight/obese patients whereas low-body-weight patients may be at risk of toxicity. This scoping review evaluated whether overweight/obese patients are at risk of below-target exposure with fixed-dose SC trastuzumab, whether low-body-weight patients are at risk of increased toxicity, especially cardiotoxicity, and whether IV and SC trastuzumab are equivalent in terms of treatment-emergent adverse events (TEAEs) (e.g. infections). Thirty-seven publications that met the eligibility criteria were included. Body weight is not an important determinant of exposure to trastuzumab at steady state (i.e. pre-dose cycle 8); however, real-world evidence suggests that the target concentration (20 μg/mL) may not be reached with the first SC dose in overweight/obese patients. There is no evidence that low-body-weight patients are at increased risk of cardiotoxicity with SC trastuzumab, although this may be confounded by the higher rate of cardiovascular comorbidities in overweight patients. In Phase 3 trials, SC trastuzumab was associated with higher rates of ISRs, ADAs and SAEs, the latter often requiring hospitalization and occurring during adjuvant treatment when patients are not burdened by chemotherapy. The route of administration of trastuzumab (IV vs SC) in different treatment settings should be discussed with the patient, taking into account the risks and benefits associated with each route.

Drug Exposure to Establish Pharmacokinetic-Response Relationships in Oncology

In the oncology field, understanding the relationship between the dose administered and the exerted effect is particularly important because of the narrow therapeutic index associated with anti-cancer drugs and the high interpatient variability. Therefore, in this review, we provide a critical perspective of the different methods of characterising treatment exposure in the oncology setting. The increasing number of modelling applications in oncology reflects the applicability and the impact of pharmacometrics on all phases of the drug development process and patient management as well. Pharmacometric modelling is a worthy component within the current paradigm of model-based drug development, but pharmacometric modelling techniques are also accessible for the clinician in the optimisation of current oncology therapies. Consequently, the application of population models in a hospital setting by generating close collaborations between physicians and pharmacometricians is highly recommended, providing a systematic means of developing and assessing model-based metrics as 'drivers' for various responses to treatments, which can then be evaluated as predictors for treatment success. Characterising the key determinants of variability in exposure is of particular importance for anticancer agents, as efficacy and toxicity are associated with exposure. We present the different strategies to describe and predict drug exposure that can be applied depending on the data available, with the objective of obtaining the most useful information in the patients' favour throughout the full drug cycle. Therefore, the objective of the present article is to review the different approaches used to characterise a patient's exposure to oncology drugs, which will result in a better understanding of the time course of the response and the magnitude of interpatient variability.

Clinical and Immunologic Responses to a B-Cell Epitope Vaccine in Patients with HER2/neu-Overexpressing Advanced Gastric Cancer-Results from Phase Ib Trial IMU.ACS.001

PURPOSE

HER2/neu is overexpressed in up to 30% of gastroesophageal adenocarcinomas (GEA) and linked to poor prognosis. Recombinant mAbs to treat HER2/neu-overexpressing cancers are effective with limitations, including resistance and toxicity. Therefore, we developed a therapeutic B-cell epitope vaccine (IMU-131/HER-Vaxx) consisting of three fused B-cell epitopes from the HER2/neu extracellular domain coupled to CRM197 and adjuvanted with Montanide. This phase Ib study aimed to evaluate the optimal/safe dose leading to immunogenicity and clinical responses (https//clinicaltrials.gov/ct2/show/NCT02795988).

PATIENTS AND METHODS

A total of 14 patients with HER2/neu-overexpressing GEA were enrolled, and dose escalation (10, 30, 50 μg) was performed in three cohorts (C). Immunogenicity was evaluated by HER2-specific Abs and cellular responses, clinical responses by CT scans according to RECIST version 1.1.

RESULTS

IMU-131 was safe without vaccine-related significant local/systemic reactions or serious adverse events. A total of 11 of 14 patients were evaluable for changes in tumor size and vaccine-specific immune responses. One patient showed complete, 5 partial responses, and 4 stable diseases as their best response. HER2-specific IgG levels were dose dependent. In contrast to patients in C1 and C2, all patients in C3 mounted substantial HER2-specific Ab levels. In addition, cellular vaccine responses, such as Th1-biased cytokine ratios and reduced regulatory T cell numbers, were generated. Progression-free survival was prolonged in C3, correlating with the vaccine-specific humoral and cellular responses.

CONCLUSIONS

IMU-131 was well tolerated and safe. The induced HER2-specific Abs and cellular responses were dose dependent and correlated with clinical responses. The highest dose (50 μg) was recommended for further evaluation in a phase II trial, with chemotherapy + IMU-131 or chemotherapy alone, which is currently ongoing.

Confounding factors in exposure-response analyses and mitigation strategies for monoclonal antibodies in oncology

Dose selection and optimization is an important topic in drug development to maximize treatment benefits for all patients. While exposure-response (E-R) analysis is a useful method to inform dose-selection strategy, in oncology, special considerations for prognostic factors are needed due to their potential to confound the E-R analysis for monoclonal antibodies. The current review focuses on 3 different approaches to mitigate the confounding effects for monoclonal antibodies in oncology: (i) Cox-proportional hazards modelling and case-matching; (ii) tumour growth inhibition-overall survival modelling; and (iii) multiple dose level study design. In the presence of confounding effects, studying multiple dose levels may be required to reveal the true E-R relationship. However, it is impractical for pivotal trials in oncology drug development programmes. Therefore, the strengths and weaknesses of the other 2 approaches are considered, and the favourable utility of tumour growth inhibition-overall survival modelling to address confounding in E-R analyses is described. In the broader scope of oncology drug development, this review discusses the downfall of the current emphasis on E-R analyses using data from single dose level trials and proposes that development programmes be designed to study more dose levels in earlier trials.

Neratinib-Induced Duodenal Ulcer: A Case Report

We report a case of a 37-year-old woman who developed a duodenal ulcer while receiving adjuvant neratinib for HER2 positive breast cancer. The clinical course of abdominal pain was strongly correlated with the use of neratinib. An esophagogastroduodenoscopy (EGD) was performed and confirmed the diagnosis of a large duodenal ulcer. Neratinib was stopped, and the patient was treated with a proton pump inhibitor. Repeat EGD performed 3 months later showed complete resolution of the duodenal ulcer. Given this unexpected serious adverse event and only modest benefit of neratinib in the adjuvant setting, the decision was made to forgo further treatment with neratinib. Physicians should be aware of the gastrointestinal (GI) side effects associated with neratinib and recognize that peptic ulcer disease may be another GI toxicity associated with neratinib use.