Pathologic complete response to neoadjuvant anti-HER2 therapy is associated with HER2 immunohistochemistry score in HER2-positive early breast cancer

NGS mutational status on first diagnostic tissue, liquid biopsy and mastectomy in G2-G3 breast cancer

Breast cancer is one of the more frequently diagnosed cancers leading to death in women, and, like other tumor types, it is heterogeneous in its immunophenotype. It harbors mutations that modify tumor aggressiveness, therapy responses, residual disease, drug resistance, and relapse rates in advanced stages. This study aims to assess the mutational status of G2 and G3 tumors using next-generation sequencing (NGS) on initial tissue biopsies, liquid biopsies, and mastectomy specimens. The histopathological (HP) diagnosis for the 32 selected cases was established via Hematoxylin-Eosin (HE) staining by two observers. For the immunohistochemical (IHC) testing of estrogen receptor (ER), progesterone receptor (PGR) and human epidermal growth factor receptor 2 (HER2), we used the Ventana BenchMark Ultra. Ki67 testing was conducted using Bond-III from Leica. For cases with a score of 2+, gene amplification was assessed by silver-enhanced in situ hybridization (ISH) (SISH; Inform HER2 Dual ISH) on Ventana BenchMark Ultra. NGS analysis was initially performed on biopsies and plasma, and later on mastectomy specimens. After automated deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) extraction, concentrations were measured using the Invitrogen Qubit system. Libraries were created using Oncomine systems, and sequencing and analysis were done with the Ion Torrent system. Most tumors were graded as G3 (19 cases), with Luminal A being the predominant molecular subtype, and a significant number displayed HER2∕HER2-low characteristics (24 out of 32 cases). The NGS assessment showed that phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations were the most frequent across all sample types. A significant limitation was the high number of invalid plasma tests due to pre-analytical handling errors or transport issues. Nonetheless, plasma testing (liquid biopsy) proved useful for monitoring tumor evolution and assessing residual disease.

A Phase II Study of Neoadjuvant PLD/Cyclophosphamide and Sequential nab-Paclitaxel Plus Dual HER2 Blockade in HER2-Positive Breast Cancer

BACKGROUND

Neoadjuvant trastuzumab/pertuzumab (HP) plus chemotherapy for HER2-positive breast cancer (BC) achieved promising efficacy. The additional cardiotoxicity still existed. Brecan study evaluated the efficacy and safety of neoadjuvant pegylated liposomal doxorubicin (PLD)/cyclophosphamide and sequential nab-paclitaxel based on HP (PLD/C/HP-nabP/HP).

PATIENTS AND METHODS

Brecan was a single-arm phase II study. Eligible patients with stages IIA-IIIC HER2-positive BC received 4 cycles of PLD, cyclophosphamide, and HP, followed by 4 cycles of nab-paclitaxel and HP. Definitive surgery was scheduled after 21 days for patients completing treatment or experiencing intolerable toxicity. The primary endpoint was the pathological complete response (pCR).

RESULTS

Between January 2020 and December 2021, 96 patients were enrolled. Ninety-five (99.0%) patients received 8 cycles of neoadjuvant therapy and all underwent surgery with 45 (46.9%) breast-conserving surgery and 51 (53.1%) mastectomy. The pCR was 80.2% (95%CI, 71.2%-87.0%). Four (4.2%) experienced left ventricular insufficiency with an absolute decline in LVEF (43%-49%). No congestive heart failure and ≥grade 3 cardiac toxicity occurred. The objective response rate was 85.4% (95%CI, 77.0%-91.1%), including 57 (59.4%) complete responses and 25 (26.0%) partial responses. The disease control rate was 99.0% (95%CI, 94.3%-99.8%). For overall safety, ≥grade 3 AEs occurred in 30 (31.3%) and mainly included neutropenia (30.2%) and asthenia (8.3%). No treatment-related deaths occurred. Notably, age of >30 (P = .01; OR = 5.086; 95%CI, 1.44-17.965) and HER2 IHC 3+ (P = .02; OR = 4.398; 95%CI, 1.286-15.002) were independent predictors for superior pCR (ClinicalTrials.gov Identifier NCT05346107).

CONCLUSION

Brecan study demonstrated the encouraging safety and efficacy of neoadjuvant PLD/C/HP-nabP/HP, suggesting a potential therapeutic option in HER2-positive BC.

Differential response of HER2-positive breast cancer to anti-HER2 therapy based on HER2 protein expression level

BACKGROUND

Increasing data indicate that HER2-positive (HER2 + ) breast cancer (BC) subtypes exhibit differential responses to targeted anti-HER2 therapy. This study aims to investigate these differences and the potential underlying molecular mechanisms.

METHODS

A large cohort of BC patients (n = 7390) was utilised. The clinicopathological characteristics and differential gene expression (DGE) of HER2+ immunohistochemical (IHC) subtypes, specifically HER2 IHC 3+ and IHC 2 + /Amplified, were assessed and correlated with pathological complete response (pCR) and survival in the neoadjuvant and adjuvant settings, respectively. The role of oestrogen receptor (ER) status was also investigated.

RESULTS

Compared to HER2 IHC 3+ tumours, BC patients with IHC 2 + /Amplified showed a significantly lower pCR rate (22% versus 57%, P < 0.001), shorter survival regardless of HER2 gene copy number, were less classified as HER2 enriched, and enriched for trastuzumab resistance and ER signalling pathway genes. ER positivity significantly decreased response to anti-HER2 therapy in IHC 2 + /Amplified, but not in IHC 3 + BC patients.

CONCLUSION

In HER2 + BC, overexpression of HER2 protein is the driver of the oncogenic pathway, and it is the main predictor of response to anti-HER2 therapy. ER signalling pathways are more dominant in BC with equivocal HER2 expression. personalised anti-HER2 therapy based on IHC classes should be considered.

Predictors of successful neoadjuvant treatment in HER2‑positive breast cancer

The prognosis of local or locally advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer after a complete response from neoadjuvant systemic treatment (NAT) is excellent. However, some of the patients succumb to their disease, so novel predictive factors to identify these patients at risk are needed. Retrospective data from 119 patients treated at the Helsinki University Hospital Comprehensive Cancer Centre (Helsinki, Finland) were collected. All patients had in situ hybridization-confirmed HER2-positive breast cancer and underwent NAT with a curative intention. The primary tumours were relatively large, most patients had cytologically confirmed lymph node metastases and the treatments used were current regimens. A total of 63 (52.1%) patients had a pathological complete response (pCR) to neoadjuvant therapy. Achieving pCR predicted longer disease-free survival (DFS; P=0.0083) but not overall survival (P=0.061). The patients with a pCR had an estimated DFS rate of 96.8% at 5 years, compared with only 59.7% of the patients with non-pCR. Radiological complete response (CR) was associated with pCR (P=0.00033), although imaging yielded 30.4% false-negative and 36.9% false-positive results. The association between the radiological CR and pCR was more obvious in oestrogen receptor-negative tumours. Moderate (compared with strong) immunohistochemical HER2 expression predicted a lower chance of pCR (P=0.0078) and worse breast cancer-specific survival (P=0.0015). In conclusion, pCR after NAT served as an important prognostic factor in women with high-risk HER2-positive breast cancer. The patients with only moderate immunohistochemical HER2 expression had a lower chance of reaching a pCR, as well as a shorter breast cancer-specific survival.

PR status is a more decisive factor in efficacy of adding pertuzumab into neoadjuvant therapy for HER2-positive and lymph node-positive breast cancer than ER status: a real-world retrospective study in China

BACKGROUND

Although neoadjuvant trastuzumab and pertuzumab (HP)-based regimens are recommended for human epidermal receptor-positive (HER2 +)/lymph node-positive (N +) breast cancer (BC) patients according to NCCN guidelines, it is undeniable that many patients achieved pathological complete response (pCR) after trastuzumab (H)-based regimens without adding pertuzumab to treatment. Patients who specifically benefit from pertuzumab must be identified. The aim of this retrospective study was to evaluate progesterone receptor (PR) status as a predictor of response to the addition of pertuzumab in HER2 + /N + breast cancer.

METHODS

One hundred forty-two patients who were diagnosed as HER2 + /N + BC without distant metastasis and followed by neoadjuvant HP-based or H-based therapy were retrospectively included. The endpoints were pCR and disease-free survival (DFS) times.

RESULTS

In total, the pCR occurred in 25 of 87 patients (28.74%) in group H compared with 32 of 55 (58.18%) in group HP. The results revealed that hormone receptor (HR) status was significantly different on pCR in group HP. The odds of pCR for patients who have HR-positive tumors were 0.160 times (P = 0.011) that for patients with HR-negative tumors by multivariable analysis. Moreover, a similar probability of PR-positive (PR +) patients, whatever estrogen receptor (ER) status was, achieving pCR in group HP was observed. The ROC curves showed different anti-HER2 regimens provide worst predictive value in the PR + cohort (N = AUC = 0.521, 95% CI: 0.348-0.694, P = 0.813) compared with the overall cohort (AUC = 0.644, 95% CI: 0.550-0.738, P = 0.004) and ER + cohort (AUC: 0.559, 95% CI: 0.405-0.713, P = 0.451). And PR status (AUC = 0.760, 95% CI: 0.626-0.894, P = 0.001) had a greater predictive value than ER status (AUC = 0.658, 95% CI: 0.508-0.807, P = 0.048) in group HP. DFS analyses were done on 141 patients. Although ER and PR status did not show significant difference in group HP (P = 0.789 and 0.088, respectively), HP-based therapy contributed to better DFS in the ER - and PR - cohorts (P = 0.035 and 0.015, respectively).

CONCLUSIONS

Compared with ER status, PR status might be a more valuable factor predicting the efficacy of adding pertuzumab into neoadjuvant therapy for HER2 + /N + BC. PR + patients benefit little from the addition of pertuzumab.

Impacts of HER2 immunohistochemical scores on response and outcomes of HER2-positive breast cancers after neoadjuvant therapy

BACKGROUND

Neoadjuvant systemic therapy (NST) is conducted in increased number of patients with breast cancer overexpressing human epidermal growth factor receptor 2 (HER2). Whether the intensity of HER2 protein expression determines response to treatment is challenged. This study aims to analyze the impact of HER2 immunohistochemical (IHC) scores on NST response and survival outcome.

METHODS

We analyzed a total of 197 patients with HER2-positive breast cancer receiving NST and definite surgery from a prospectively collected database. The analyzed endpoints included pathological complete response (pCR), disease-free survival (DFS), and overall survival (OS). More patients with IHC 2+/ in situ hybridization (ISH)-positive tumors presented positive for hormonal receptors, compared with those with IHC 3+ tumors. No clinicopathological features except tumor necrosis were significantly associated with pCR.

RESULTS

Both positive hormone receptors and IHC scores stood on the borderline in statistical analysis. IHC 3+ group tends to present a higher pCR rate than IHC 2+/ISH+ groups (52.5% vs. 34.3%). Patients who achieved pCR had better survival outcome than that of non-pCR group. The impact of pCR on survival reached the statistical significance in the IHC 3+ group both in DFS (90.9% vs. 76.5%; p = 0.004) and OS (97.4% vs. 83.2%; p = 0.002). Multivariate analysis demonstrated IHC scores as an independent predictor of survival outcome with the adjustment of tumor staging and pCR.

CONCLUSION

HER2 IHC score is an independent predictor for outcome. IHC 3+ tumors presented a trend of higher pCR rate and better outcome in HER2-positive breast cancer patients who receive NST.

Multi-institutional Assessment of Pathologist Scoring HER2 Immunohistochemistry

The HercepTest was approved 20+ years ago as the companion diagnostic test for trastuzumab in human epidermal growth factor 2 (HER2) or ERBB2 gene-amplified/overexpressing breast cancers. Subsequent HER2 immunohistochemistry (IHC) assays followed, including the now most common Ventana 4B5 assay. Although this IHC assay has become the clinical standard, its reliability, reproducibility, and accuracy have largely been approved and accepted on the basis of concordance among small numbers of pathologists without validation in a real-world setting. In this study, we evaluated the concordance and interrater reliability of scoring HER2 IHC in 170 breast cancer biopsies by 18 breast cancer-specialized pathologists from 15 institutions. We used the Observers Needed to Evaluate Subjective Tests method to determine the plateau of concordance and the minimum number of pathologists needed to estimate interrater agreement values for large numbers of raters, as seen in the real-world setting. We report substantial discordance within the intermediate categories (<1% agreement for 1+ and 3.6% agreement for 2+) in the 4-category HER2 IHC scoring system. The discordance within the IHC 0 cases is also substantial with an overall percent agreement (OPA) of only 25% and poor interrater reliability metrics (0.49 Fleiss' kappa, 0.55 intraclass correlation coefficient). This discordance can be partially reduced by using a 3-category system (28.8% vs 46.5% OPA for 4-category and 3-category scoring systems, respectively). Observers Needed to Evaluate Subjective Tests plots suggest that the OPA for the task of determining a HER2 IHC score 0 from not 0 plateaus statistically around 59.4% at 10 raters. Conversely, at the task of scoring HER2 IHC as 3+ or not 3+ pathologists' concordance was much higher with an OPA that plateaus at 87.1% with 6 raters. This suggests that legacy HER2 IHC remains valuable for finding the patients in whom the ERBB2 gene is amplified but unacceptably discordant in assigning HER2-low or HER2-negative status for the emerging HER2-low therapies.

Real-world study of trastuzumab and pertuzumab combined with chemotherapy in neoadjuvant treatment for patients with HER2-positive breast cancer

Clinical trials have shown that trastuzumab (H) and pertuzumab (P) combined with chemotherapy as neoadjuvant therapy increased pathological complete response (pCR) rate of patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, date in China in the real world are currently limited. Clinical data from patients with HER2-positive breast cancer who received HP combined with chemotherapy as neoadjuvant therapy at 2 institutions from March 2019 to February 2022 were retrospectively analyzed. Adverse reactions were evaluated using CTCAE version 5.0. The primary endpoint was total pathologic complete response (tpCR; ypT0/isypN0), and the secondary endpoints were breast pathologic complete response (bpCR; ypT0/is) and axillary pathologic complete response (apCR; ypN0). Factors influencing tpCR were also analyzed. A total of 302 patients were included in the analysis, of which 145 were treated with H + P + taxane + carboplatin (TcbHP), 94 with H + P + taxane (THP) and 63 with sequential anthracycline and cyclophosphamide, followed by H + P + taxane (AC-THP). The overall tpCR rate was 64.9%, and those of TcbHP, THP, and AC-THP were 73.1%, 52.1%, and 65.1%, respectively. The tpCR rate of the hormone receptor (HR) negative group (80.3%) was higher than that of the HR positive group (52.1%). The overall bpCR rate was 73.5% and the apCR rate was 75.8%. In the univariate analysis, HR, HER2 status and treatment regimen were related factors that affected tpCR. In the multivariate analysis, HR, HER2 status and treatment regimen were independent predictors of tpCR (P < .001, P < .001 and P = .009). The levels 3 and 4 toxicities rates of TcbHP were slightly higher than those of THP and AC-THP. HP combined with chemotherapy has achieved a high pCR rate. The TcbHP regimen had the highest pCR. HR-negative tumors demonstrated a higher pCR. HR, HER2 status and treatment regimen were independent predictors of tpCR. The adverse reactions are controllable.