Trastuzumab beyond progression for HER2 positive metastatic breast cancer: progression-free survival on first-line therapy predicts overall survival impact

Advances in the treatment of human epidermal growth factor receptor 2-positive gastric cancer

Human epidermal growth factor receptor 2 has been a pivotal biomarker for gastric cancer treatment strategies for many years. However, more than a decade after the ToGA trial demonstrated the efficacy of trastuzumab in improving survival, the development of treatments targeting human epidermal growth factor receptor 2 remains challenging. Several large-scale clinical trials of tyrosine kinase inhibitors, non-trastuzumab anti-human epidermal growth factor receptor 2 antibodies, and antibody-drug conjugates have failed to meet the primary endpoints. The concept of trastuzumab beyond progression and the complexity of resistance mechanisms to anti-human epidermal growth factor receptor 2 therapy after trastuzumab treatment presented significant obstacles, leading to trastuzumab being the sole therapy for human epidermal growth factor receptor 2-positive gastric cancer for some time. Nevertheless, the landscape has shifted in recent years, especially since the introduction of the antibody-drug conjugate trastuzumab deruxtecan in 2020. This has rekindled the interest in developing treatments targeting human epidermal growth factor receptor 2 in gastric cancer.

Termination of trastuzumab in HER2-positive metastatic breast cancer patients who received trastuzumab beyond progression

The purpose of the study was to assess the prognosis of HER2-positive metastatic breast cancer patients who received trastuzumab beyond progression and investigate the predictors of complete response. HER2-positive metastatic breast cancer patients who received long-term trastuzumab were included in the study. Predictors of complete response were analyzed with binary regression analysis. The prognosis of patients who had their trastuzumab-based treatment terminated was assessed. Eighty patients were involved in the study. The patients were received with trastuzumab for a median of 62 months (12-191). A complete response was observed in 60 (75%) patients. The median duration to development of complete response was found as 14.8 months (2.4-55). In logistic regression analysis: using endocrine therapy with trastuzumab (p = 0.04), menopausal status (p = 0.03), and the number of metastatic sites (p = 0.01) were found to be statistically significant factors for a complete response. Trastuzumab-based therapy of fifteen patients was terminated, six (40%) patients continued to receive an aromatase inhibitor, and nine (60%) patients were followed up without treatment. After termination of trastuzumab, at a median follow-up of 32 months (11-66), recurrence was detected in two (13.3%) patients. We detected that menopausal status, the number of metastatic sites, and using endocrine therapy with trastuzumab were predictors of complete response in HER2-positive metastatic breast cancer patients who received long-term trastuzumab-based therapy. We observed that HER2-positive metastatic breast cancer patients may be completely cured with trastuzumab-based therapy. There are no defined criteria for termination of trastuzumab treatment in this selected patient group. It is necessary to confirm our data with multicenter studies involving a large number of patients.

Real-world effectiveness of post-trastuzumab emtansine treatment in patients with HER2-positive, unresectable and/or metastatic breast cancer: a retrospective observational study (KBCSG-TR 1917)

BACKGROUND

Trastuzumab emtansine (T-DM1) is a second-line standard therapy for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. Evidence regarding post-T-DM1 treatments is currently lacking. We evaluated the effectiveness of post-T-DM1 drug therapy in patients with HER2-positive, unresectable and/or metastatic breast cancer.

METHODS

In this multicenter, retrospective, observational study, real-world clinical data of female patients with HER2-positive breast cancer who had a history of T-DM1 treatment were consecutively collected from five sites in Japan. We investigated the effectiveness of post-T-DM1 therapy by evaluating the real-world progression-free survival (rwPFS), time to treatment failure (TTF), overall survival (OS), objective response rate (ORR), and clinical benefit rate (CBR). Tumor response was assessed by investigators according to Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) guidelines. Subgroup and exploratory analyses according to background factors were also undertaken.

RESULTS

Of the 205 patients who received T-DM1 treatment between 1 January 2014 and 31 December 2018, 128 were included in this study. Among the 128 patients analyzed, 105 (82%) patients received anti-HER2 therapy and 23 (18%) patients received regimens without anti-HER2 therapy. Median (95% confidence interval [CI]) rwPFS, TTF, and OS were 5.7 (4.8-6.9) months, 5.6 (4.6-6.4) months, and 22.8 (18.2-32.4) months, respectively. CBR and ORR (95% CI) were 48% (38.8-56.7) and 23% (15.1-31.4), respectively. Cox-regression analysis showed that an ECOG PS score of 0, a HER2 immunohistochemistry score of 3+, recurrent type, ≥12 month duration of T-DM1 therapy, and anti-HER2 therapy were independent variables for rwPFS. An exploratory subgroup analysis of regimens after T-DM1 showed that those with anti-HER2 therapy had a median rwPFS of 6.3 and those without anti-HER2 therapy had a median rwPFS of 4.8 months.

CONCLUSIONS

In the real-world setting in Japan, several post-T-DM1 regimens for patients with unresectable and/or metastatic HER2-positive breast cancer, including continuation of anti-HER2 therapy, showed some effectiveness; however, this effectiveness was insufficient. Novel therapeutic options are still needed for further improvement of PFS and OS in later treatment settings.

TRIAL REGISTRATION

UMIN000038296 ; registered on 15 October 2019.

Multivalent exposure of trastuzumab on iron oxide nanoparticles improves antitumor potential and reduces resistance in HER2-positive breast cancer cells

Targeted therapies have profoundly changed the clinical prospect in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. In particular, the anti-HER2 monoclonal antibody trastuzumab represents the gold standard for the treatment of HER2+ breast cancer patients. Its contribution in dampening cancer progression is mainly attributed to the antibody-dependent cell-mediated cytotoxicity (ADCC) rather than HER2 blockade. Here, multiple half chains of trastuzumab were conjugated onto magnetic iron oxide nanoparticles (MNP-HC) to develop target-specific and biologically active nanosystems to enhance anti-HER2 therapeutic potential. HER2 targeting was assessed in different human breast cancer cell lines, where nanoparticles triggered site-specific phosphorylation in the catalytic domain of the receptor and cellular uptake by endocytosis. MNP-HC induced remarkable antiproliferative effect in HER2+ breast cancer cells, exhibiting enhanced activity compared to free drug. Accordingly, nanoparticles induced p27kip1 expression and cell cycle arrest in G1 phase, without loosing capability to prime ADCC. Finally, MNP-HC affected viability of trastuzumab-resistant cells, suggesting interference with the resistance machinery. Our findings indicate that multiple arrangement of trastuzumab half chain on the nanoparticle surface enhances anticancer efficacy in HER2+ breast cancer cells. Powerful inhibition of HER2 signaling could promote responsiveness of resistant cells, thus suggesting ways for drug sensitization.

High casein kinase 1 epsilon levels are correlated with better prognosis in subsets of patients with breast cancer

Reliable biological markers that predict breast cancer (BC) outcomes after multidisciplinary therapy have not been fully elucidated. We investigated the association between casein kinase 1 epsilon (CK1ε) and the risk of recurrence in patients with BC. Using 168 available tumor samples from patients with BC treated with surgery +/− chemo(radio)therapy, we scored the CK1ε expression as high (≥1.5) or low (<1.5) using an immunohistochemical method. Kaplan-Meier analysis was performed to assess the risk of relapse, and Cox proportional hazards analyses were utilized to evaluate the effect of CK1ε expression on this risk. The median age at diagnosis was 60 years (range 35-96). A total of 58% of the patients underwent breast conservation surgery, while 42% underwent mastectomy. Adjuvant chemotherapy and radiation therapy were administered in 101 (60%) and 137 cases (82%), respectively. Relapse was observed in 24 patients (14%). Multivariate analysis found high expression of CK1ε to be associated with a statistically significant higher disease-free survival (DFS) in BC patients with wild-type p53 (Hazard ratio [HR] = 0.33; 95% CI, 0.12-0.91; P = 0.018) or poor histological differentiation ([HR] = 0.34; 95% CI, 0.12-0.94; P = 0.039) or in those without adjuvant chemotherapy ([HR] = 0.11; 95% CI, 0.01-0.97; P = 0.006). Our data indicate that CK1ε expression is associated with DFS in BC patients with wild-type p53 or poor histological differentiation or in those without adjuvant chemotherapy and thus may serve as a predictor of recurrence in these subsets of patients.

Efficacy and safety of trastuzumab combined with chemotherapy for first-line treatment and beyond progression of HER2-overexpressing advanced breast cancer

Objective

To observe the efficacy and safety of trastuzumab combined with chemotherapy in patients with human epidermal growth factor receptor 2 (HER2)-overexpressing advanced breast cancer.

Methods

A total of 90 patients with HER2-overexpressing advanced breast cancer were enrolled in this study. All patients were diagnosed with ductal invasive breast cancer by pathological analysis, and were aged between 31–73 years with a median of 51 years. HER2-positivity was defined as 3(+) staining in immunochemistry or amplification of fluorescence in situ hybridization (FISH, ratio ≥2.0). Trastuzumab was administered in combination with chemotherapy as first-line treatment and beyond progression as a secondline, third-line, and above treatment in 90, 34, 14, and 6 patients, respectively. The chemotherapy regimen was given according to normal clinical practice. The response rate was evaluated every two cycles, and the primary endpoints were progression-free survival (PFS) and overall survival (OS). Survival curves were estimated by using Kaplan-Meier graphs and were compared by using log-rank test statistics. Multivariate analysis was done using Cox’s proportional hazards regression model, and the level of significance was P<0.05.

Results

All 90 patients received at least one dose of trastuzumab, and efficacy could be evaluated in 85 patients. The median follow-up was 50 months. In total, 72 (80.00%) patients had visceral metastasis, and 43 (47.78%) patients had progressed after one or more extensive chemotherapy regimens for metastatic diseases. The median PFS for first-line trastuzumab was 10 months (range, 2–59 months), and the median OS after metastasis or initially local advanced disease was 22 months (range, 2–116 months).

Conclusions

Trastuzumab combined with chemotherapy was active and well-tolerated as a first-line treatment and even beyond progression in HER2-overexpressing advanced breast cancer as a second-line or third-line treatment. However, its efficacy is certainly less beyond this point.