Individualizing Curative-Intent Therapy in HER2-Positive Early-Stage Breast Cancer

OPINION STATEMENT

Human epidermal growth factor receptor 2-positive (HER2+) breast cancers have been historically considered an aggressive entity with high rates of recurrence and poor survival. However, during the last 20 years, there has been a dramatic change in prognosis due to the incorporation of different anti-HER2 therapies into the neo/adjuvant chemotherapy backbone. Neoadjuvant dual blockade with trastuzumab and pertuzumab has become the standard of care for women with stage II and III HER2+ breast cancer. Trastuzumab emtansine (T-DM1) has been shown to improve outcomes if pathological complete response (pCR) is not achieved, and adjuvant extended therapy with neratinib has increased disease-free survival (DFS) and may have an impact in central nervous system (CNS) recurrences. However, these agents are both toxic for individual patients and costly for the overall healthcare system, and there are still patients that experience recurrence despite therapy improvements. At the same time, it has been shown that some patients with early-stage HER2+ breast cancer can be effectively treated with less intensive systemic therapy, using only taxane and trastuzumab, or that the chemotherapy backbone can be omitted completely. The current challenge is to properly identify which patients can receive a de-intensified regimen and which need new intensification strategies. Tumor size, nodal status, and pCR achievement after neoadjuvant treatment are well-known risk factors that can aid in making clinical decisions, but they do not accurately predict all patient outcomes. Various biomarkers have been proposed to better characterize the clinical and biological heterogeneity of HER2+ breast cancer. Immune infiltration, intrinsic subtype, intratumoral heterogeneity, and dynamic changes during treatment have been described as important prognostic and/or predictive features. The integration of all these factors will be key in the proper identification of the true risk, and individualized treatment strategy, for each patient.

ORLNC1 Suppresses Cell Growth in HER2-Positive Breast Cancer via miRNA-296 Sponging

BACKGROUND

Accumulating research has demonstrated that aberrant levels of long noncoding RNAs (LncRNAs) are related to cancer progression. The effects of ORLNC1 in HER2+ breast cancer have yet to be explored.

METHODS

Real-time PCR was used to examine the expression of LncRNA ORLNC1 in HER+ breast cancer. CCK-8, wound healing and cell invasion assays were used to examine the effect of LncRNA ORLNC1 on HER+ breast cancer cells. Luciferase reporter assay was utilized to determine the regulatory relationship between LncRNA ORLNC1 and miR-296. Western blotting was used to measure the expression of PTEN. Xenograft mouse model was used to examine the effect of LncRNA ORLNC1 on tumor progression in vivo.

RESULTS

In this study, our findings revealed downregulation of ORLNC1 in HER2+ breast cancer specimens and cell lines. Low levels of ORLNC1 were related to poor prognosis and advanced cancer stage. Using gain- and loss-of-function assays, the ability of these tumor cells to proliferate was found to be inhibited by ORLNC1 in vitro and in vivo. Further analyses revealed that miR-296/PTEN axis is directly targeted by ORLNC1. Consequently, over-expression of miR-296 efficiently abrogated the upregulation of PTEN induced by ORLNC1, suggesting that ORLNC1 positively regulates PTEN expression by competitively binding to miR-296.

CONCLUSION

Our results indicate that lncRNA ORLNC1 acts as a tumor suppressor by regulating the miR-296/PTEN axis in HER2+ breast cancer.

PIK3CAMutations in Breast Cancer Subtypes Other Than HR-Positive/HER2-Negative

The phosphoinositide 3-kinase (PI3K) pathway plays a key role in cancer, influencing growth, proliferation, and survival of tumor cells. PIK3CA mutations are generally oncogenic and responsible for uncontrolled cellular growth. PI3K inhibitors (PI3Ki) can inhibit the PI3K/AKT/mTOR pathway, although burdened by not easily manageable toxicity. Among PI3Ki, alpelisib, a selective p110α inhibitor, is approved for the treatment of hormone receptor (HR)+/HER2- PIK3CA mutant metastatic breast cancer (BC) that has progressed to a first line endocrine therapy. PIK3CA mutations are also present in triple negative BC (TNBC) and HER2+ BC, although the role of PI3K inhibition is not well established in these subtypes. In this review, we go through the PI3K/AKT/mTOR pathway, describing most common mutations found in PI3K genes and how they can be detected. We describe the available biological and clinical evidence of PIK3CA mutations in breast cancers other than HR+/HER2-, summarizing clinical trials investigating PI3Ki in these subtypes.

Trastuzumab resistance in HER2-positive breast cancer: Mechanisms, emerging biomarkers and targeting agents

Trastuzumab is a standard molecular targeted therapy for human epidermal growth factor receptor 2(HER2) -positive breast cancer, which can significantly improve the survival of patients with this molecular subtype of breast cancer. However, the clinical problem of onset or secondary resistance to trastuzumab has limited its efficacy. Therefore, it is very important to explore the mechanism of trastuzumab resistance and formulate countermeasures. Our study described the underlying molecular mechanism of trastuzumab resistance including ERBB2 mutations and nuclear localization, transcriptional and post-translational alterations of ERBB2, over-activation of bypass signaling pathways activation and so on. Then summarize the potential emerging predicting biomarkers and therapeutic strategies for trastuzumab resistance, in order to provide research direction for reversing trastuzumab resistance.

Perioperative HER2 targeted treatment in early stage HER2-positive breast cancer

Although human epidermal growth factor receptor 2 (HER2)-positive breast cancer was associated with poor prognosis, it has been changed after the development of trastuzumab. There has been great progress in perioperative HER2-targeting treatment, and investigations of several novel drugs and their combinations are ongoing. Adjuvant trastuzumab with or without pertuzumab for 1 year in combination with concomitant chemotherapy has become a standard treatment in high-risk node-negative tumors or node-positive HER2-positive early breast cancer patients without residual disease or who have not received neoadjuvant treatment. For low-risk HER2-positive early breast cancer patients, adjuvant paclitaxel and 1-year trastuzumab are possible alternatives. For residual disease after neoadjuvant treatment, adjuvant trastuzumab emtansine (T-DM1) for 14 cycles is a standard treatment. Non-anthracycline chemotherapy with dual anti-HER2 targeting of trastuzumab and pertuzumab represents one of the preferred neoadjuvant regimens to achieve higher pathologic complete response (pCR) rates and better clinical outcomes. Further research is needed to develop and validate potential biomarkers to predict pCR, which could help escalate or de-escalate anti-HER2 therapy. Trials incorporating novel agents such as T-DM1, trastuzumab deruxtecan (T-DXd), and immune checkpoint inhibitors and trying to de-escalate treatments in neoadjuvant setting are ongoing. In the future, tailored treatments such as no adjuvant therapy, various HER2-directed therapies alone with chemotherapy, combinations of various HER2-directed therapies and chemotherapy, addition of immune checkpoint inhibitors, and omission of surgery will be individualized in HER2-positive early breast cancer patients.

Anthracycline-Free Neoadjuvant Treatment in Patients with HER2-Positive Breast Cancer: Real-Life Use of Pertuzumab, Trastuzumab and Taxanes Association with an Exploratory Analysis of PIK3CA Mutational Status

Simple Summary

This retrospective observational study aims at highlighting the response to pertuzumab, trastuzumab and docetaxel treatment (THP), without using anthracycline, in patients with HER2-positive early breast cancer. We add evidence to the suitability of THP in real life to reach higher pathological complete response rates, with a good safety profile for patients. An exploratory analysis of the mutational status of PIK3CA was performed as well, and 21% mutated samples were identified, with overall higher pCR rates in PIK3CA mutant patients and, particularly, in those who were THP-treated. Our original results open the door to further studies focused on more in-depth analysis of the molecular and clinical features related to the response to anthracycline-free neoadjuvant treatment in HER2-positive early breast cancer patients.

Abstract

HER2 is considered one of the most traditional prognostic and predictive biomarkers in breast cancer. Literature data confirmed that the addition of pertuzumab to a standard neoadjuvant chemotherapy backbone (either with or without anthracyclines), in patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC), leads to a higher pathological complete response (pCR) rate, which is known to correlate with a better prognosis. In this retrospective analysis, 47 consecutive patients with HER2-positive EBC received sequential anthracyclines and taxanes plus trastuzumab (ATH) or pertuzumab, trastuzumab and docetaxel (THP). Despite the limited sample size, this monocentric experience highlights the efficacy (in terms of pCR) and safety of THP in the neoadjuvant setting of HER2-positive EBC as an anthracycline-free approach. Given the role of PIK3CA as a prognostic and therapeutic target in breast cancer, tumors were also analyzed to assess the PIK3CA mutational status. Thirty-eight out of forty-seven patients were evaluated, and PIK3CA variants were identified in 21% of tumor samples: overall, one mutation was detected in exon 4 (2.6%), two in exon 9 (5.3%) and four in exon 20 (10.5%). Of note, one sample showed concurrent mutations in exons 9 (codon 545) and 20 (codon 1047). Among patients reaching pCR (n = 13), 38.5% were PIK3CA mutants; on the other hand, among those lacking pCR (n = 25), just 12% showed PIK3CA variants. Regarding THP-treated mutant patients (n = 5), 80% reached pCR (three hormone-receptor-negative, one hormone-receptor-positive). Interestingly, the only patient not achieving pCR had a tumor with two co-occurring PIK3CA mutations. In conclusion, this study provides new evidence about the efficacy and good safety profile of THP, compared to the ATH regimen, as an anthracycline-free neoadjuvant treatment of HER2-positive EBC. Further studies on larger/multicentric cohorts are planned for more in-depth analysis to confirm our molecular and clinical results.

PIK3CA Mutations Drive Therapeutic Resistance in Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

The phosphatidylinositol 3-kinase (PI3K) pathway is an intracellular pathway activated in response to progrowth signaling, such as human epidermal growth factor receptor 2 (HER2) and other kinases. Abnormal activation of PI3K has long been recognized as one of the main oncogenic drivers in breast cancer, including HER2-positive (HER2+) subtype. Somatic activating mutations in the gene encoding PI3K alpha catalytic subunit (PIK3CA) are present in approximately 30% of early-stage HER2+ tumors and drive therapeutic resistance to multiple HER2-targeted agents. Here, we review currently available agents targeting PI3K, discuss their potential role in HER2+ breast cancer, and provide an overview of ongoing trials of PI3K inhibitors in HER2+ disease. Additionally, we review the landscape of PIK3CA mutational testing and highlight the gaps in knowledge that could present potential barriers in the effective application of PI3K inhibitors for treatment of HER2+ breast cancer.

The modern views of the clinical, morphological and molecular biological predictors of breast cancer sensitivity to chemotherapy

In the treatment of breast cancer, the neoadjuvant chemotherapy is vitally important and the evaluation of its effectiveness is crucial for determining the further therapy treatment, as well as the prognosis of the disease. This review provides current data of the physical, instrumental, morphological, molecular biology and genetics analysis used for the estimation of the neoadjuvant treatment effectiveness. Thus, review discusses the data concerning association of the disease peculiarities with the efficient therapeutic response to neoadjuvant chemotherapy including characteristics of patients (age, status of regional lymph nodes, presence of the lymphovascular invasion) and tumors (size, histological type, degree of differentiation, severity of the lymphoid tumor infiltration, molecular biological and genetic peculiarities). Particular attention is paid to such a promising predictive marker of the breast cancer response to chemotherapy as the level of tissue hypoxia. This section discusses the currently known mechanisms that might enable the effect of tissue hypoxia on the sensitivity of the tumor to drug treatment. The prospects for the use of a comprehensive analysis of predictive markers of the effectiveness of chemotherapeutic treatment are discussed.

PIK3CA Mutation in the ShortHER Randomized Adjuvant Trial for Patients with Early HER2+ Breast Cancer: Association with Prognosis and Integration with PAM50 Subtype

PURPOSE

We explored the prognostic effect of PIK3CA mutation in HER2⁺ patients enrolled in the ShortHER trial.

PATIENTS AND METHODS

The ShortHER trial randomized 1,253 patients with HER2⁺ breast cancer to 9 weeks or 1 year of adjuvant trastuzumab combined with chemotherapy. PIK3CA hotspot mutations in exon 9 and 20 were analyzed by pyrosequencing. Expression of 60 genes, including PAM50 genes was measured using the nCounter platform.

RESULTS

A mutation of the PIK3CA gene was detected in 21.7% of the 803 genotyped tumors. At a median follow-up of 7.7 years, 5-year disease-free survival (DFS) rates were 90.6% for PIK3CA mutated and 86.2% for PIK3CA wild-type tumors [HR, 0.84; 95% confidence interval (CI), 0.56-1.27; P = 0.417]. PIK3CA mutation showed a favorable prognostic impact in the PAM50 HER2-enriched subtype (n = 232): 5-year DFS 91.8% versus 76.1% (log-rank P = 0.049; HR, 0.46; 95% CI, 0.21-1.02). HER2-enriched/PIK3CA mutated versus wild-type tumors showed numerically higher tumor-infiltrating lymphocytes (TIL) and significant upregulation of immune-related genes (including CD8A, CD274, PDCD1, and MYBL2, a proliferation gene involved in immune processes). High TILs as well as the upregulation of PDCD1 and MYBL2 were associated with a significant DFS improvement within the HER2-enriched subtype (HR, 0.82; 95% CI, 0.68-0.99; P = 0.039 for 10% TILs increment; HR, 0.81; 95% CI, 0.65-0.99; P = 0.049 for PDCD1 expression; HR, 0.72; 95% CI, 0.53-0.99; P = 0.042 for MYBL2 expression).

CONCLUSIONS

PIK3CA mutation showed no prognostic impact in the ShortHER trial. Within the HER2-enriched molecular subtype, patients with PIK3CA mutated tumors showed better DFS versus PIK3CA wild-type, which may be partly explained by upregulation of immune-related genes.

Using Phosphatidylinositol Phosphorylation as Markers for Hyperglycemic Related Breast Cancer

Studies have suggested that type 2 diabetes (T2D) is associated with a higher incidence of breast cancer and related mortality rates. T2D postmenopausal women have an ~20% increased chance of developing breast cancer, and women with T2D and breast cancer have a 50% increase in mortality compared to breast cancer patients without diabetes. This correlation has been attributed to the general activation of insulin receptor signaling, glucose metabolism, phosphatidylinositol (PI) kinases, and growth pathways. Furthermore, the presence of breast cancer specific PI kinase and/or phosphatase mutations enhance metastatic breast cancer phenotypes. We hypothesized that each of the breast cancer subtypes may have characteristic PI phosphorylation profiles that are changed in T2D conditions. Therefore, we sought to characterize the PI phosphorylation when equilibrated in normal glycemic versus hyperglycemic serum conditions. Our results suggest that hyperglycemia leads to: 1) A reduction in PI3P and PIP3, with increased PI4P that is later converted to PI(3,4)P2 at the cell surface in hormone receptor positive breast cancer; 2) a reduction in PI3P and PI4P with increased PIP3 surface expression in human epidermal growth factor receptor 2-positive (HER2+) breast cancer; and 3) an increase in di- and tri-phosphorylated PIs due to turnover of PI3P in triple negative breast cancer. This study begins to describe some of the crucial changes in PIs that play a role in T2D related breast cancer incidence and metastasis.

Comutation of PIK3CA and TP53 in Residual Disease After Preoperative Anti-HER2 Therapy in ERBB2 (HER2)-Amplified Early Breast Cancer

PURPOSE

To identify proteomic and genomic alterations in residual disease (RD) for human epidermal growth factor receptor 2 (HER2)-positive (HER2+) breast cancer (BC) after preoperative trastuzumab (H), lapatinib (L), or both (H+L) in combination with chemotherapy.

PATIENTS AND METHODS

Patients with stage II/III HER2+ BC (n = 100) were randomly assigned to preoperative treatment with H versus L 1,250mg versus H+L (L: 750 to 1,000 mg) plus 5-fluorouracil, epirubicin, and cyclophosphamide, followed by weekly paclitaxel. After receiving institutional review board–approved informed consent, targeted next-generation sequencing was performed on 20 patients’ formalin-fixed paraffin embedded tumors to characterize genomic alterations across 287 cancer-related genes. Reverse phase protein array (RPPA) analysis was performed on both the baseline biopsy and RD specimens, when available.

RESULTS

Two of 20 RD tissues were HER2 negative per next-generation sequencing; one sample had insufficient tissue. Of six pretreatment biopsy specimens, four were comutated with TP53 and PIK3CA. Of 17 HER2+ RD, seven specimens (41%) had PIK3CA mutations always comutated with TP53, and four (24%) also had concurrent CDK12 amplification. Overall, CDK12 amplification was observed in eight of the 17 (47%) HER2+ RD specimens. A total of 12 RD specimens (71%) had TP53 mutations. Although prevalence of individual TP53 and PIK3CA mutations was only modestly higher than published estimates for those in HER2+ primary BCs (55% and 32% for TP53 and PIK3CA, respectively), prevalence of these as comutations appeared higher (41%), compared with less than 10% in several series. On RPPA analysis of the RD tissue with comutations, the strongest Spearman ρ correlations were limited to EGFR and phospho-AKT (ρ, 0.999; P = .019) and phospho-mTOR and phospho-S6 ribosomal protein (ρ, 0.994; P = .048).

CONCLUSION

HER2-amplified RD tissue after preoperative H, L, or H+L plus chemotherapy was enriched for PIK3CA and TP53 comutations, and the RD tissue demonstrated activation of EGFR/AKT/mTOR signaling on RPPA.

A Phase II Randomized Study of Neoadjuvant Letrozole Plus Alpelisib for Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer (NEO-ORB)

PURPOSE

Addition of alpelisib to fulvestrant significantly extended progression-free survival in PIK3CA-mutant, hormone receptor-positive (HR+) advanced/metastatic breast cancer in the phase III SOLAR-1 study. The combination of alpelisib and letrozole also had promising activity in phase I studies of HR+ advanced/metastatic breast cancer. NEO-ORB aimed to determine whether addition of alpelisib to letrozole could increase response rates in the neoadjuvant setting.Patients and Methods: Postmenopausal women with HR+, human epidermal growth factor receptor 2-negative, T1c-T3 breast cancer were assigned to the PIK3CA-wild-type or PIK3CA-mutant cohort according to their tumor PIK3CA status, and randomized (1:1) to 2.5 mg/day letrozole with 300 mg/day alpelisib or placebo for 24 weeks. Primary endpoints were objective response rate (ORR) and pathologic complete response (pCR) rate for both PIK3CA cohorts.

RESULTS

In total, 257 patients were assigned to letrozole plus alpelisib (131 patients) or placebo (126 patients). Grade ≥3 adverse events (≥5% of patients) in the alpelisib arm were hyperglycemia (27%), rash (12%), and maculo-papular rash (8%). The primary objective was not met; ORR in the alpelisib versus placebo arm was 43% versus 45% and 63% versus 61% in the PIK3CA-mutant and wild-type cohorts, respectively. pCR rates were low in all groups. Decreases in Ki-67 were similar across treatment arms and cohorts. In PIK3CA-mutant tumors, alpelisib plus letrozole treatment induced a greater decrease in phosphorylated AKT versus placebo plus letrozole.

CONCLUSIONS

In contrast to initial results in advanced/metastatic disease, addition of alpelisib to 24-week neoadjuvant letrozole treatment did not improve response in patients with HR+ early breast cancer.

PIK3CA Mutations and Neoadjuvant Therapy Outcome in Patients with Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: A Sequential Analysis

Purpose

PIK3CA mutation is considered to be a possible cause for resistance to neoadjuvant chemotherapy (NAC) in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. We investigated the association between PIK3CA mutations and the outcome of NAC in HER2-positive breast cancers.

Methods

A total of 100 HER2-positive breast cancer patients who had undergone NAC and surgery between 2004 and 2016 were examined. Mutation status was sequentially assessed in pre-NAC, post-NAC, and recurrent specimens taken from these patients.

Results

PIK3CA mutations were identified in the sequential specimens of 17 patients (17.0%). These 17 patients experienced shorter disease-free survival (DFS) than the rest of the patients (58.3 months vs. 119.3 months, p=0.020); however, there was no significant difference in pathologic complete response (pCR) and overall survival (OS) (pCR, 17.6% vs. 33.7%, p=0.191; OS, 84.5 months vs. 118.0 months, p=0.984). While there was no difference in pCR between the wild-type and mutant PIK3CA groups in pre-NAC specimens (25.0% vs. 31.8%, p=0.199), PIK3CA mutations correlated with lower pCR in post-NAC specimens (0.0% vs. 24.3%, p<0.001). Multivariate analysis revealed significantly worse DFS in the mutant PIK3CA group than in the wild-type group (hazard ratio, 3.540; 95% confidence interval, 1.001–12.589; p=0.050). Moreover, the DFS curves of the change of PIK3CA mutation status in sequential specimens were significantly different (p=0.016).

Conclusion

PIK3CA mutation in HER2-positive breast cancer was correlated with a lower pCR rate and shorter DFS. These results suggest that PIK3CA mutation is a prognostic marker for NAC in HER2-positive breast cancer, especially in post-NAC specimens.