Trastuzumab deruxtecan in breast cancer

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) consisting of a humanised, anti-human epidermal growth factor receptor 2 (HER2) monoclonal antibody covalently linked to a topoisomerase I inhibitor cytotoxic payload (DXd). The high drug-to-antibody ratio (8:1) ensures a high DXd concentration is delivered to target tumour cells, following internalisation of T-DXd and subsequent cleavage of its tetrapeptide-based linker. DXd's membrane-permeable nature enables it to cross cell membranes and potentially exert antitumour activity on surrounding tumour cells regardless of HER2 expression. T-DXd's unique mechanism of action is reflected in its efficacy in clinical trials in patients with HER2-positive advanced breast cancer (in heavily pretreated populations and in those previously treated with a taxane and trastuzumab), as well as HER2-low metastatic breast cancer. Thus, ADCs such as T-DXd have the potential to change the treatment paradigm of targeting HER2 in metastatic breast cancer, including eventually within the adjuvant/neoadjuvant setting.

The role of irreversible pan-HER tyrosine kinase inhibitors in the treatment of HER2-Positive metastatic breast cancer

Human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) is the leading cause of cancer death in women. For patients with HER2-positive MBC, after the failure of multiple lines of treatment, there is no optimal line of therapy. A series of clinical trials confirmed that treatment with irreversible pan-HER tyrosine kinase inhibitors (TKIs) in combination with chemotherapy significantly improves patients' survival outcomes. This review focuses on the pathogenesis of HER2-positive breast cancer, current standard treatments, mechanisms of approved irreversible TKIs, and key clinical trials. The available findings suggest that irreversible pan-HER TKIs, such as pyrotinib and neratinib, in combination with chemotherapy, represent a beneficial salvage therapy for patients with HER2-positive MBC with manageable toxicity. However, further studies are needed to assess the efficacy and safety of this combination therapy.

Final results of the global and Asia cohorts of KAMILLA, a phase IIIB safety trial of trastuzumab emtansine in patients with HER2-positive advanced breast cancer

Background

KAMILLA is a single-arm safety study of trastuzumab emtansine (T-DM1) in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer (BC; NCT01702571). We report the final analysis of cohort 2 (Asia) within the context of published cohort 1 (Global) findings.

Methods

Patients had HER2-positive, locally advanced, or metastatic BC progressing after chemotherapy and anti-HER2 therapy or ≤6 months after adjuvant therapy. The primary objective was to further evaluate T-DM1 (3.6 mg/kg, administered intravenously every 3 weeks) safety/tolerability, including the following adverse events of primary interest (AEPIs): grade ≥3 AEPIs (hepatic events, allergic reactions, thrombocytopenia, hemorrhage events), all grade ≥3 treatment-related AEs, and all-grade pneumonitis.

Results

KAMILLA enrolled 2185 patients (cohort 1, n = 2003; cohort 2, n = 182) as of 31 July 2019. Of these, 2002 and 181 per cohort were treated and included in the safety population. Approximately 70% of patients had two or more previous treatment lines in the metastatic setting. Median T-DM1 exposure was 5.6 and 5.0 months per cohort; median follow-up was 20.6 and 15.1 months. The overall AEPI rate was higher in cohort 2 (93/181; 51.4%) versus cohort 1 (462/2002; 23.1%), mostly driven by a higher grade ≥3 thrombocytopenia rate in cohort 2. In cohort 2, grade ≥3 thrombocytopenia was not associated with grade ≥3 hemorrhagic events and most (128/138) fully resolved. Grade ≥3 treatment-related AEPI rates were 18.4% (cohort 1) and 48.6% (cohort 2), the latter mainly due to thrombocytopenia. Any-grade pneumonitis rates were 1.0% and 2.2%. No new safety signals were identified. Median (95% confidence interval) progression-free survival was 6.8 months (5.8-7.6 months) and 5.7 months (5.5-7.0 months) in cohorts 1 and 2, respectively; median overall survival was 27.2 months (25.5-28.7 months) and 29.5 months (21.1 months to non-estimable). In both cohorts, median progression-free survival and overall survival decreased with increasing prior therapy lines.

Conclusions

Cohort 2 results aligned with previous findings in Asian patients, supporting the manageable safety profile and use of T-DM1 in advanced BC.

•

KAMILLA safety results for cohorts 1 (global; n = 2002) and 2 (Asia; n = 181) aligned with results from prior T-DM1 mBC trials.

•

The overall rate of adverse events of primary interest (AEPIs) was higher in cohort 2 (51.4%) versus cohort 1 (23.1%).

•

The higher AEPI rate was mostly due to a higher grade ≥3 thrombocytopenia event rate in cohort 2, most of which resolved.

•

Median PFS and OS were similar for both cohorts, and decreased with increasing prior therapy lines.

•

The manageable safety profile and efficacy of T-DM1 further support its favorable benefit/risk balance.

T-DM1 after Pertuzumab plus Trastuzumab: Treatment Sequence-Induced Selection Bias in HER2-Positive Metastatic Breast Cancer

Real-world studies have suggested decreased trastuzumab emtansine (T-DM1) effectiveness in patients with metastatic breast cancer (mBC) who received prior trastuzumab plus pertuzumab (H + P). However, these studies may have been biased toward pertuzumab-experienced patients with more aggressive disease. Using an electronic health record-derived database, patients diagnosed with mBC on/after 1 January 2011 who initiated T-DM1 in any treatment line (primary cohort) or who initiated second-line T-DM1 following first-line H ± P (secondary cohort) from 22 February 2013 to 31 December 2019 were included. The primary outcome was time from index date to next treatment or death (TTNT). In the primary cohort (n = 757), the percentage of patients with prior P increased from 37% to 73% across the study period, while population characteristics and treatment effectiveness measures were generally stable. Among P-experienced patients from the secondary cohort (n = 246), median time from mBC diagnosis to T-DM1 initiation increased from 10 to 14 months (2013-2019), and median TTNT increased from 4.4 to 10.2 months (2013-2018). Over time, prior H + P prevalence significantly increased with no observable impact on T-DM1 effectiveness. Drug approval timing should be considered when assessing treatment effectiveness within a sequence.

Mechanisms contributing to ado-trastuzumab emtansine-induced toxicities: a gateway to better understanding of ADC-associated toxicities

In order to improve the safety of novel therapeutic drugs, better understanding of the mechanisms of action is important. Ado-trastuzumab emtansine (also known as T-DM1) is an antibody-drug conjugate (ADC) approved for the treatment of HER2-positive breast cancer. While the treatment with T-DM1 results in significant efficacy in the selected patient population, nonetheless, there are concerns with side effects such as thrombocytopenia and hepatotoxicity. While current understanding of the mechanism of T-DM1-mediated side effects is still incomplete, there have been several reports of HER2-dependent and/or -independent mechanisms that could be associated with the T-DM1-induced adverse events. This review highlights the importance of HER2-independent mechanism of T-DM1 to induce hepatotoxicity, which offers a new insight into a role for CKAP5 in the overall maytansinoid-based ADC (DM1 and DM4)-mediated cytotoxicity. This discovery provides a molecular basis for T-DM1-induced off-target toxicity and opens a new avenue for developing the next generation of ADCs.

Cardiotoxicity during long-term trastuzumab use in patients with HER2-positive metastatic breast cancer: who needs cardiac monitoring?

Purpose

Patients with HER2-positive metastatic breast cancer (MBC) usually receive many years of trastuzumab treatment. It is unknown whether these patients require continuous left ventricular ejection fraction (LVEF) monitoring. We studied a real-world cohort to identify risk factors for cardiotoxicity to select patients in whom LVEF monitoring could be omitted.

Methods

We included patients with HER2-positive MBC who received > 1 cycle of trastuzumab-based therapy in eight Dutch hospitals between 2000 and 2014. Cardiotoxicity was defined as LVEF < 50% that declined > 10%-points and was categorized into non-severe cardiotoxicity (LVEF 40–50%) and severe cardiotoxicity (LVEF < 40%). Multivariable Cox and mixed model analyses were performed to identify risk factors associated with cardiotoxicity. Additionally, we explored the reversibility of cardiotoxicity in patients who continued trastuzumab.

Results

In total, 429 patients were included. Median follow-up for cardiotoxicity was 15 months (interquartile range 8–31 months). The yearly incidence of non-severe + severe cardiotoxicity in the first and second year was 11.7% and 9.1%, respectively, which decreased thereafter. The yearly incidence of severe cardiotoxicity was low (2.8%) and stable over time. In non-smoking patients with baseline LVEF > 60% and no cardiotoxicity during prior neoadjuvant/adjuvant treatment, the cumulative incidence of severe cardiotoxicity was 3.1% after 4 years of trastuzumab. Despite continuing trastuzumab, LVEF decline was reversible in 56% of patients with non-severe cardiotoxicity and in 33% with severe cardiotoxicity.

Conclusions

Serial cardiac monitoring can be safely omitted in non-smoking patients with baseline LVEF > 60% and without cardiotoxicity during prior neoadjuvant/adjuvant treatment.

Supplementary Information

The online version of this article (10.1007/s10549-020-06039-w) contains supplementary material, which is available to authorized users.

Neratinib plus capecitabine for the treatment of advanced HER2-positive breast cancer

INTRODUCTION

Several agents are being developed for advanced HER2-positive breast cancer, such as potent tyrosine kinase inhibitors (TKI) targeting ErbB family receptors, novel antibody-drug conjugates, higher affinity anti-HER2 antibodies, among others. Neratinib is an irreversible pan-HER (EGFR, ERBB2, and ERBB4) TKI being tested in early and advanced HER2-positive breast cancer. In the NALA trial, neratinib plus capecitabine led to increased PFS and time to intervention for central nervous system disease over the standard regimen of lapatinib plus capecitabine. The main adverse event in the neratinib arm was diarrhea, which mandates for prophylactic treatment with loperamide.

AREAS COVERED

In this review, we analyze and discuss preclinical and clinical data with neratinib plus capecitabine. We summarize efficacy and safety results from phase I/II and III trials, and discuss this regimen within the landscape of treatment for patients with HER2-positive metastatic breast cancer progressing after two lines of HER2-directed treatment.

EXPERT OPINION

Neratinib plus capecitabine is a valid treatment option for patients with advanced HER2-positive breast cancer, after progression to at least two anti-HER2-based regimens. Given the multiple options that are being developed in this context, efforts should be employed to establish strong predictive biomarkers of efficacy to each drug and combination.

Impact of BMI on HER2+ metastatic breast cancer patients treated with pertuzumab and/or trastuzumab emtansine. Real-world evidence

Body mass index (BMI) is a main indicator of obesity and its association with breast cancer is well established. However, little is known in the metastatic setting, especially in HER2-positive patients. We assessed the influence of BMI on clinical outcomes of patients treated with pertuzumab and/or trastuzumab emtansine (T-DM1) for HER2+ metastatic breast cancer (mBC). BMI was addressed as a categorical variable, being classified on the basis of the following ranges, that is, 18.5-24.9, 25-29.9, and 30.0-34.9, namely, normal weight, overweight, and Class I obesity. The outcomes chosen were progression-free survival to first-line chemotherapy (PFS1) and overall survival (OS). Overall (N = 709), no impact of BMI was observed on PFS1 (p = .15), while BMI ≥ 30 was associated with worse OS (p = .003). In subjects who progressed to first line (N = 575), analyzing data across PFS1 quartiles and strata of disease burden, BMI predicted lower PFS1 in patients within the I PFS1 quartile and with the lowest disease burden (p = .001). Univariate analysis showed a detrimental effect of BMI ≥ 30 on OS for women within the I PFS1 quartile (p = .03). Results were confirmed in multivariate analysis. According to PFS1 quartiles a higher percentage of patients with high BMI and low disease burden progressed within 6 months of therapy. The effect of BMI on prognosis was also confirmed in multivariate analysis of OS for overall population. In our cohort, a BMI ≥ 30 correlated with worse OS in patients with HER2+ mBC who received pertuzumab and/or T-DM1 but had no impact on PFS to first line. BMI predicted worse I PFS1 quartile.

Survival and cardiac toxicity in patients with HER2-positive, metastatic breast cancer treated with trastuzumab in routine clinical practice

AIMS

We sought to describe survival outcomes and toxicities of trastuzumab in real-world patients with HER2-positive, metastatic breast cancer (MBC) and compare these to a recent systematic review of clinical trials.

METHODS

We searched the medical records of three Sydney cancer centers for patients with HER2-positive, MBC starting trastuzumab from January 2001 to March 2017. We recorded patient, tumor, and treatment characteristics; survival times from start of palliative trastuzumab; and rates of cardiac toxicity. Survival distribution was summarized using the following percentiles (represented scenario): 90th (worst-case), 75th (lower-typical), 25th (upper-typical), and 10th (best-case). Survival times were compared to recent review of HER2-positive MBC randomized trials. Factors associated with survival were assessed with Cox models.

RESULTS

Characteristics of the 126 patients were: median age 53 years, ER positive cancer (50%), de-novo metastatic disease (23%), prior adjuvant trastuzumab (15%), liver metastases (37%), and brain metastases (23%). The median duration of first-line trastuzumab was 11 months (interquartile range, (IQR) 5-27). Survival times in months (vs the systematic review) were: 90th percentile 8 (9); 75th percentile 16 (19); and median 34 (33). Follow-up duration was insufficient to estimate the 25th and 10th percentiles, similar to the systematic review. Liver metastases were associated with shorter survival (HR = 1.74, 95% CI, 1.1-2.76, P = .02). Seventy percent of patients had a baseline cardiac assessment. Five patients (3.9%) developed symptomatic cardiac toxicity, similar to clinical trials.

CONCLUSION

Survival and cardiac toxicity rates for women starting trastuzumab in routine practice were comparable to clinical trials. Oncologists can use clinical trial data as a reference point when explaining survival outcomes to women with HER2-positive MBC.

De Novo Versus Recurrent HER2-Positive Metastatic Breast Cancer: Patient Characteristics, Treatment, and Survival from the SystHERs Registry

Background

Limited data exist describing real‐world treatment of de novo and recurrent HER2‐positive metastatic breast cancer (MBC).

Materials and Methods

The Systemic Therapies for HER2‐Positive Metastatic Breast Cancer Study (SystHERs) was a fully enrolled (2012–2016), observational, prospective registry of patients with HER2‐positive MBC. Patients aged ≥18 years and ≤6 months from HER2‐positive MBC diagnosis were treated and assessed per their physician's standard practice. The primary endpoint was to characterize treatment patterns by de novo versus recurrent MBC status, compared descriptively. Secondary endpoints included patient characteristics, progression‐free and overall survival (PFS and OS, by Kaplan‐Meier method; hazard ratio [HR] and 95% confidence interval [CI] by Cox regression), and patient‐reported outcomes.

Results

Among 977 eligible patients, 49.8% (n = 487) had de novo and 50.2% (n = 490) had recurrent disease. A higher proportion of de novo patients had hormone receptor–negative disease (34.9% vs. 24.9%), bone metastasis (57.1% vs. 45.9%), and/or liver metastasis (41.9% vs. 33.1%), and a lower proportion had central nervous system metastasis (4.3% vs. 13.5%). De novo patients received first‐line regimens containing chemotherapy (89.7%), trastuzumab (95.7%), and pertuzumab (77.8%) more commonly than recurrent patients (80.0%, 85.9%, and 68.6%, respectively). De novo patients had longer median PFS (17.7 vs. 11.9 months; HR, 0.69; 95% CI, 0.59–0.80; p < .0001) and OS (not estimable vs. 44.5 months; HR, 0.55; 95% CI, 0.44–0.69; p < .0001).

Conclusion

Patients with de novo versus recurrent HER2‐positive MBC exhibit different disease characteristics and survival durations, suggesting these groups have distinct outcomes. These differences may affect future clinical trial design. Clinical trial identification number. NCT01615068 (http://clinicaltrials.gov).

Implications for Practice

SystHERs was an observational registry of patients with HER2‐positive metastatic breast cancer (MBC), which is a large, modern, real‐world data set for this population and, thereby, provides a unique opportunity to study patients with de novo and recurrent HER2‐positive MBC. In SystHERs, patients with de novo disease had different baseline demographics and disease characteristics, had superior clinical outcomes, and more commonly received first‐line chemotherapy and/or trastuzumab versus those with recurrent disease. Data from this and other studies suggest that de novo and recurrent MBC have distinct outcomes, which may have implications for disease management strategies and future clinical study design.

The SystHERs breast cancer study was a fully enrolled, prospective registry study that explored contemporary treatment patterns and outcomes in patients with HER2‐positive metastatic breast cancer (MBC), resulting in one of the largest real‐world datasets for this population and providing a unique opportunity to assess patients with de novo and recurrent HER2‐positive MBC. This article reports baseline characteristics, treatment patterns, patient‐reported outcomes, and clinical outcomes in these patient subsets.

Androgen receptor expression inversely correlates with immune cell infiltration in human epidermal growth factor receptor 2-positive breast cancer

INTRODUCTION

Although targeting human epidermal growth factor receptor 2 (HER2) is a meaningful treatment in HER2-positive breast cancer, ultimately resistance develops. Androgen receptor (AR) expression and immune cell infiltration are thought to be involved in trastuzumab response and may, therefore, be of interest as additional targets for therapy in HER2-positive breast cancer.

AIM

To improve insights into the presence among AR expression, immune cell infiltration and HER2, we analysed HER2-positive breast tumours.

METHODS

Primary tumours of 221 patients treated with trastuzumab for metastatic disease were selected. HER2 status was centrally confirmed. AR, T-cells (CD3 and CD8), programmed cell death protein 1 (PD-1) and PD-1 ligand 1 immunohistochemical staining and M2 tumour-associated macrophages (TAMs; CD68 and CD163) immunofluorescence were performed. Tumour-infiltrating lymphocytes were evaluated by haematoxylin and eosin staining.

RESULTS

Sufficient tumour material was available for 150 patients. Oestrogen receptor was expressed in 51.3% of the tumours and AR in 81.3% of the tumours. AR expression was inversely correlated with M2 TAM (Pearson's r = -0.361, P < 0.001), CD3+ (r = -0.199, P < 0.030) and CD8+ (r = -0.212, P < 0.021) T-cell infiltration. Clustering analysis showed high immune cell infiltration in AR low-expressing tumours, and low immune cell infiltration in AR-high expressing tumours.

CONCLUSION

AR expression inversely correlates with immune cell infiltration in HER2-positive breast cancer.

Trastuzumab for metastatic breast cancer: Real world outcomes from an Australian whole-of-population cohort (2001-2016)

PURPOSE

Outcomes for patients treated in clinical trials may not reflect the experience in routine clinical care. We aim to describe the real-world treatment patterns and overall survival (OS) for women receiving trastuzumab for metastatic breast cancer (MBC).

METHODS

Retrospective, whole-of-population cohort study using demographic, dispensing, and medical services data for women in the Herceptin Program for HER2+MBC. We estimated time on trastuzumab and OS from first dispensing of trastuzumab for MBC and rates of cardiac monitoring prior to and during treatment. We stratified outcomes by two groups based on year of initiation: 2001-2008 and 2009-2015. We benchmarked outcomes to two key trastuzumab clinical trials: H0648g (median OS 25 months) and CLEOPATRA (control group median OS 41 months).

RESULTS

Median age of the 5899 women at first trastuzumab dispensing was 57 years (interquartile range [IQR]: 48-66). Median time on trastuzumab increased from 15 months (7-33) in Group One to 18 months (8-42) in Group Two. Median OS increased from 27 months (12-57) in Group One to 38 months (16-83) in Group Two. Rates of cardiac monitoring increased at baseline (52%-76%), and on-treatment (47%-67%), in Group One and Two, respectively.

CONCLUSIONS

OS, duration of trastuzumab, and frequency of cardiac monitoring increased over the study period. Outcomes for trastuzumab in this heterogeneous real world population were reassuringly comparable to those from clinical trials, with the median OS > 3 years in Group Two and 25% of patients living 7 years or longer.

Parameterization of a disease progression simulation model for sequentially treated metastatic human epidermal growth factor receptor 2 positive breast cancer patients

Background The objective of this study is twofold: 1) to propose a simulation model for HER2+ metastatic breast cancer (mBC) which could further be used to assess the overall cost-effectiveness of the treatment sequences that would maximize survival of patients, and 2) to estimate transitional probabilities between treatment lines required to parameterize the simulation model, in the absence of individual patient data (IPD). Methods Individual patient data (IPD) were reconstructed for treatment lines composing four treatment sequences. Parametric models were tested to select the model that best fits the IPD. The transitional probability equations, used for disease progression modeling, were obtained by substituting the parameters of the general equation for transitional probabilities by the parameters estimated from fitted distributions. Results The log-logistic model best fitted the reconstructed data for progression-free and overall survival curves for each line of treatment. The shapes and scales of the log-logistic models were used to develop the transitional probability equations for the HER2+ mBC simulation model.

KEY LIMITATIONS

The estimation of the transitional probabilities depends heavily on the accuracy of the IPD reconstruction. Nonetheless, analytical and graphical tests can be performed to check the face validity of the reconstructed data. Additionally, sensitivity analyses can be conducted to test the impact of uncertainty surrounding the estimated parameters defining equations for transitional probabilities. Conclusion The results of this study can be used as input in model-based economic evaluations of sequential therapy for HER2+ mBC.

T-DM1 as a New Treatment Option for Patients with Metastatic HER2-positive Breast Cancer in Clinical Practice

AIM

To compare results of trastuzumab-emtansine (T-DM1) treatment in our clinical practice with data from phase III clinical trials.

PATIENTS AND METHODS

A retrospective chart review of all 23 patients with metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer who were started on T-DM1 until April 2014 was performed.

RESULTS

Four patients (17.4%) received T-DM1 as first-line, three (13.0%) as second-line, six (26.0%) as third-line, and 10 (43.5%) as fifth- or further-line therapy. Overall, the response rate (ORR) was 26.0%, disease control rate 78.3% and median progression-free survival (PFS) 8.4 months. The only toxicities of grade 3 or more were fatigue (21.7%), thrombocytopenia (4.3%) and elevation of liver enzymes (8.7%). ORR and PFS were similar to the TH3RESA and EMILIA trials. Compared to the EMILIA study, we recorded higher rates of newly-diagnosed cerebral metastasis and cerebral progression in patients with stable peripheral metastases.

CONCLUSION

T-DM1 is effective and well-tolerated even in intensively pre-treated patients.

Safety profile of Pertuzumab with Trastuzumab and Docetaxel in patients from Asia with human epidermal growth factor receptor 2-positive metastatic breast cancer: results from the phase III trial CLEOPATRA

INTRODUCTION

We report detailed safety analyses by geographic region from the phase III study CLEOPATRA with pertuzumab, trastuzumab, and docetaxel in patients with human epidermal growth factor receptor 2 (HER2)-positive first-line metastatic breast cancer.

PATIENTS AND METHODS

Patients received pertuzumab/placebo at 840 mg in cycle 1 and 420 mg in subsequent cycles, and trastuzumab at 8 mg/kg in cycle 1 and 6 mg/kg in subsequent cycles; docetaxel was initiated at 75 mg/m(2). All study drugs were given intravenously, 3 times weekly.

RESULTS

Docetaxel dose reductions below 75 mg/m(2) were more common in patients from Asia (47.0%) than other regions (13.4%); docetaxel dose escalations to 100 mg/m(2) were less frequent in Asia (2.4%) than other regions (18.7%). Rates of edema (26.1% and 5.4% for Asia and other regions, respectively), myalgia (42.3%, 14.7%), nail disorder (39.9%, 15.1%), febrile neutropenia (18.6%, 7.1%), upper respiratory tract infection (25.7%, 10.2%), decreased appetite (47.0%, 19.1%), and rash (44.3%, 22.0%) were at least twice as high in Asia as in other regions. Adverse events did not result in a reduction in the median number of study treatment cycles administered in patients from Asia. Efficacy analyses per region showed hazard ratios similar to those of the whole intention-to-treat (ITT) population for progression-free survival (ITT: 0.63; Asia: 0.68; other regions: 0.61) and overall survival (ITT: 0.66; Asia: 0.64; other regions: 0.66).

CONCLUSION

Despite a higher proportion of docetaxel dose reductions in patients from Asia, survival benefits were comparable between regions. The benefit-risk profile of pertuzumab, trastuzumab, and docetaxel supports this regimen as the first-line therapy for patients with HER2-positive metastatic breast cancer from all geographic regions.