De novo resistance biomarkers to anti-HER2 therapies in HER2-positive breast cancer

Apatinib and trastuzumab-based chemotherapy for heavily treated primary trastuzumab-resistant metastatic breast cancer

BACKGROUND

The low incidence and poor prognosis primary trastuzumab resistance (PTR) in HER2-positive breast cancer has limited research into possible treatments. Thus, it remains unclear whether this group of patients could benefit from nontargeting HER2 antiangiogenic therapy.

PATIENTS AND METHODS

We collected the medical data for HER2-positive patients with PTR who received apatinib 250 mg and trastuzumab-based chemotherapy (ATBC) between March 18, 2017, and March 31, 2022. All patients had progressed on ≥2 anti-HER2 treatments, including trastuzumab and small molecular tyrosine kinase inhibitors. We evaluated tumor response and safety profiles to ATBC over a median follow-up time of 34.5 months.

RESULTS

A total of 198 consecutively HER2-positive metastatic breast cancer patients were reviewed; 20 were PTR and received ATBC. The clinical benefit rate of the total cohort was 55.0%. No patient showed a complete response. The median PFS and overall survival (OS) of the entire cohort was 5.7 months (95% CI 2.9-8.5) and 24.6 months (95% CI 6.9-42.4), respectively. The estimated 2-year survival rate was 46.7% (95% CI 38.4-81.6%). The most common nonhematologic adverse events were hypertension (70.0%), hand-foot skin reaction (55.0%), proteinuria (40.0%), and cardiovascular decrease of LVEF (20.0%). No new toxicities were observed.

CONCLUSION

ATBC had favorable effects for PTR breast cancer patients in later line treatment. The toxicity of the triple-combination regimen was tolerable; thus, further research should focus on identifying PTR patients who could benefit from ATBC.

Screening of GPCR drugs for repurposing in breast cancer

Drug repurposing can overcome both substantial costs and the lengthy process of new drug discovery and development in cancer treatment. Some Food and Drug Administration (FDA)-approved drugs have been found to have the potential to be repurposed as anti-cancer drugs. However, the progress is slow due to only a handful of strategies employed to identify drugs with repurposing potential. In this study, we evaluated GPCR-targeting drugs by high throughput screening (HTS) for their repurposing potential in triple-negative breast cancer (TNBC) and drug-resistant human epidermal growth factor receptor-2-positive (HER2+) breast cancer (BC), due to the dire need to discover novel targets and drugs in these subtypes. We assessed the efficacy and potency of drugs/compounds targeting different GPCRs for the growth rate inhibition in the following models: two TNBC cell lines (MDA-MB-231 and MDA-MB-468) and two HER2+ BC cell lines (BT474 and SKBR3), sensitive or resistant to lapatinib + trastuzumab, an effective combination of HER2-targeting therapies. We identified six drugs/compounds as potential hits, of which 4 were FDA-approved drugs. We focused on β-adrenergic receptor-targeting nebivolol as a candidate, primarily because of the potential role of these receptors in BC and its excellent long-term safety profile. The effects of nebivolol were validated in an independent assay in all the cell line models. The effects of nebivolol were independent of its activation of β3 receptors and nitric oxide production. Nebivolol reduced invasion and migration potentials which also suggests its inhibitory role in metastasis. Analysis of the Surveillance, Epidemiology and End Results (SEER)-Medicare dataset found numerically but not statistically significant reduced risk of all-cause mortality in the nebivolol group. In-depth future analyses, including detailed in vivo studies and real-world data analysis with more patients, are needed to further investigate the potential of nebivolol as a repurposed therapy for BC.

Primary Trastuzumab Resistance After (Neo)adjuvant Trastuzumab-containing Treatment for Patients With HER2-positive Breast Cancer in Real-world Practice

BACKGROUND

It is difficult to define patients with primary trastuzumab resistance (PTR) after (neo)adjuvant trastuzumab with minimal data and understanding of the actual prevalence, prognosis, and potential treatment strategies in the real-world setting.

PATIENTS AND METHODS

The medical records of 1096 patients with human epidermal growth factor receptor 2-positive early-stage breast cancer who had received (neo)adjuvant trastuzumab-containing treatment from 2010 to 2016 in the Cancer Hospital and Chinese Academy of Medical Sciences were reviewed. PTR was defined as recurrence during adjuvant trastuzumab or within 12 months from their last (neo)adjuvant trastuzumab dosage. The cutoff date for data collection was September 1, 2018, with a median follow-up time of 46 months.

RESULTS

A total of 126 recurrences were observed, and 75 (6.8%; 75/1096) of them were categorized as PTR; the remaining were non-PTR. The prognosis of patients in the PTR group was much inferior to those in the non-PTR group (27 months vs. not reached; P < .01). As expected, patients with PTR did possess a much lower response rate to first-line trastuzumab-containing therapy (27.3% vs. 61.9%; P = .02). Subgroup analyses indicated that patients in the PTR group seemed to get little survival benefit from the reuse of trastuzumab compared with those without trastuzumab (26 months vs. 28 months; P = .80). However, in the non-PTR group, re-treatment with trastuzumab in the metastatic setting prolonged the survival of patients compared to those without trastuzumab (not reached vs. 34 months; P = .04).

CONCLUSION

This study verified the rationality of present definition of PTR after (neo)adjuvant trastuzumab. Patients with PTR did have a poor prognosis. Further research and clinical trials are required to establish the best treatment patterns for these patients.

Cullin7 enhances resistance to trastuzumab therapy in Her2 positive breast cancer via degrading IRS-1 and downregulating IGFBP-3 to activate the PI3K/AKT pathway

Patients with Her2-positive breast cancer exhibit de novo resistance or develop acquired resistance in less than one year after Her2 targeting treatment, but the mechanism is not fully elucidated. Compensatory pathways such as the IGF-1R/IRS-1 pathway, are activated, leading to aberrant enhanced PI3K/Akt/mTOR pathway activity to attenuate the efficacy of trastuzumab. Cullin7 could participate in the degradation of IRS-1 in a mTOR/S6K dependent manner. Whether Cullin7 participates in trastuzumab resistance needs to be further investigated. Here, we reveals that Cullin7 is overexpressed in trastuzumab-resistant Her2 positive breast cancer cells. Knockdown of Cullin7 reduces degradation of Ser phosphorylation of IRS-1, attenuates activation of the PI3K/AKT pathway, and partly restores trastuzumab sensitivity in trastuzumab-resistant Her2 positive breast cancer cells. IGFBP-3 expression is decreased in trastuzumab-resistant Her2 positive breast cancer cells, which leads to release of the Wnt signaling pathway inhibition and an increase in Cullin7 expression, as mediated by TCF7L2. Overexpression of Cullin7 in Her2-amplified breast cancer tissues has clinical implications because it positively correlates with shorter disease-free survival (DFS) and inadequate response to trastuzumab. Thus, our results suggest a critical role for Cullin7 in response to trastuzumab, which has significant implications for selection of the optimal therapeutic strategy for Her2 positive breast cancers.

NK-mediated antibody-dependent cell-mediated cytotoxicity in solid tumors: biological evidence and clinical perspectives

The process of antibody-dependent cell-mediated cytotoxicity (ADCC) makes use of the innate immune cells providing antitumor cytotoxicity activated by antibodies linked to target cells. Natural killer (NK) cells are a small set of lymphocytes, but are considered the most important cells among those able to induce ADCC. They provoke innate immune responses and harmonise spontaneous cytotoxicity towards tumor and virus-infected cells. They are able to swiftly produce biochemical signals and cytokines so as to stimulate subsequent adaptive immune responses. Immunotherapeutics that target NK cells, augmenting their immune response, can cause the antitumor dynamics of the antibodies to be improved. The recent developments in the field of NK cell immunotherapy and genotypic factors which might affect patient responses to antibody-dependent immunotherapies are the main subject of this review, with a particular focus on the manipulations and strategies used to augment ADCC. In the next years combined treatment with monoclonal antibodies (mAbs) and immunomodulatory drugs will be an important part in antitumor therapy. The main challenge remains the difficulty in distinguishing in the clinical setting, between the target effect that many mAbs exert against specific cell membrane receptors and the ADCC effect that they too also can induce. Drugs able to activate NK cells, that are major actors in mAb-mediated ADCC, will improve the ADCC effect against tumors.

SP1 promotes tumor angiogenesis and invasion by activating VEGF expression in an acquired trastuzumab‑resistant ovarian cancer model

Ovarian cancer is one of the most common gynecologic cancers and the leading cause of mortality in women worldwide. HER2/neu is overexpressed in various types of cancers and is most commonly associated with decreased survival. Trastuzumab is a humanized anti-HER2 monoclonal antibody for the treatment of HER2-positive breast cancers. However, primary and/or acquired resistance occurs in up to 62% patients during the first year of treatment. Vascular endothelial growth factor (VEGF) is a well‑known angiogenesis factor involved in many physiological and pathological processes. Its significance has been implicated in promoting tumor growth and metastasis via angiogenesis. In the present study, we demonstrated that the upregulation of SP1 enhanced expression of VEGF promoting the angiogenesis and migration of trastuzumab-resistant ovarian cancer cell line SKOV3-T. Our in vitro and in vivo results both gave evidence that the SP1-VEGF axis was responsible for the enhanced malignancy, angiogenesis and migration in the acquired trastuzumab-resistant ovarian cancer cell model.

Non-HER2 signaling pathways activated in resistance to anti-HER2 therapy in breast cancer

HER2 receptor is overexpressed approximately in 20 % of human breast cancer (BC) and is a poor prognostic factor. Although therapies targeting this receptor have improved the prognosis of this cancer, up to 62 % patients treated with these drugs experiment progression during the first year of treatment. Some molecular mechanisms have been proposed to be responsible for this resistance, such as activation of alternative signaling pathways (through ERBB receptors and non-ERBB receptors or increased expression of ligands and alterations in HER2 signaling components). In this article, we will review the influence of genetic markers in non-HER2 signaling pathways investigated to date as cause of resistance to HER2-targeted drugs in HER2-positive BC patients. GRB7, included in the 17q12 amplicon, has been associated to poor prognosis in BC patients. Biomarkers like EPHAR and SRC, have demonstrated clinical relevance and prognostic value in HER2-positive BC patients. Non-invasive biomarkers, such as elevated IGF1 serum levels have been revealed as interesting biomarkers to be considered as predictors of trastuzumab clinical outcomes in BC patients. However, the prognostic value of most of the biomarkers investigated to date, such as HER3, IGF1R, PIK3CA, or AKT1 cannot be fully established yet, since results have not been conclusive.