Aromatase inhibitors: the journey from the state of the art to clinical open questions

Breast cancer is a major cause of death among females. Great advances have been made in treating this disease, and aromatase inhibitors (AIs) have been recognized as the cornerstone. They are characterized by high efficacy and low toxicity. The authors reviewed the available literature and defined state-of-the-art AI management. This study was designed to assist clinicians in addressing the need to equally weigh patients' needs and disease control rates in their everyday clinical practice. Today, AIs play a central role in the treatment of hormone receptor-positive breast cancer. In this study, an expert panel reviewed the literature on the use of AIs, discussing the evolution of their use in various aspects of breast cancer, from pre- and postmenopausal early breast cancer to metastatic breast cancer, along with their management regarding efficacy and toxicity. Given the brilliant results that have been achieved in improving survival in everyday clinical practice, clinicians need to address their concerns about therapy duration and the adverse effects they exert on bone health, the cardiovascular system, and metabolism. Currently, in addition to cancer treatment, patient engagement is crucial for improving adherence to therapy and supporting patients' quality of life, especially in a selected subset of patients, such as those receiving an extended adjuvant or combination with targeted therapies. A description of modern technologies that contribute to this important goal is provided.

Impact of CDK4/6 Inhibitors on Aromatase Inhibitor-Associated Musculoskeletal Syndrome (AIMSS) in the Adjuvant Setting

Background

Third-generation aromatase inhibitors (AIs) are the mainstay of treatment in hormone receptor (HR)-positive breast cancer. Even though it is considered to be a well-tolerated therapy, AI-induced musculoskeletal symptoms are common and may be accused for treatment discontinuation. Recently, selective cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors changed the therapeutic setting, and currently, ribociclib, palbociclib, and abemaciclib are all approved in combination with nonsteroidal AIs in patients with ER-positive, HER2-negative advanced or metastatic breast cancer. This systematic review aims to identify the frequency of aromatase inhibitor-associated musculoskeletal syndrome (AIMSS) in the adjuvant setting in patients under AI monotherapy compared to patients under combination therapy with AIs and CDK4/6 inhibitors and demonstrate the underlying mechanism of action.

Methods

This study was performed in accordance with PRISMA guidelines. The literature search and data extraction from all randomized clinical trials (RCTs) were done by two independent investigators. Eligible articles were identified by a search of MEDLINE and ClinicalTrial.gov database concerning the period 2000/01/01-2021/05/01.

Results

Arthralgia was reported in 13.2 to 68.7% of patients receiving AIs for early-stage breast cancer, while arthralgia induced by CDK4/6 inhibitors occurred in a much lower rate [20.5-41.2%]. Bone pain (5-28.7% vs. 2.2-17.2%), back pain (2-13.4% vs. 8-11.2%), and arthritis (3.6-33.6% vs. 0.32%) were reported less frequently in patients receiving the combination of CDK4/6 inhibitors with ET.

Conclusions

CDK4/6 inhibitors might have a protective effect against joint inflammation and arthralgia occurrence. Further studies are warranted to investigate arthralgia incidence in this population.

Cost-effectiveness of Tamoxifen, Aromatase Inhibitor, and Switch Therapy (Adjuvant Endocrine Therapy) for Breast Cancer in Hormone Receptor Positive Postmenopausal Women in India

Background

Breast cancer is the leading cause of cancer among women in India. Treatment with hormone therapy reduces recurrence. We undertook this cost-effectiveness study to ascertain the treatment option offering the best value for money.

Methods

The lifetime costs and health outcomes of using tamoxifen, AI and switch therapy were measured in a cohort of 50-year-old women with HR-positive early stage breast cancer. A Markov model of disease was developed using a societal perspective with a lifetime study horizon. Local, contralateral, and distant recurrence were modelled along with treatment related adverse effects. Primary data collected to obtain estimates of out-of-pocket expenditure (OOPE) and utility weights. Both health system cost and OOPE were included. The future costs and consequences were discounted at 3%. A probabilistic sensitivity analysis was used.

Results

The lifetime cost of hormone therapy with tamoxifen, AI and switch therapy was to be ₹1,472,037 (I$ 68,947), ₹1,306,794 (I$ 61,208) and ₹1,281,811 (I$ 60,038). The QALYs lived per patient receiving tamoxifen, AI and switch were 13.12, 13.42 and 13.32. tamoxifen was found to be more expensive and less effective. As compared to switch therapy, AI for five years incurred an incremental cost of ₹259,792 (I$12,168) per QALY gained. At the willingness to pay equals to per capita GDP of India, there is 55% probability of AI therapy to be cost-effective compared to switch therapy.

Conclusion

In postmenopausal women with HR-positive early-stage breast cancer, switch therapy is recommended for use on the basis of cost-effectiveness.

Extended therapy with letrozole as adjuvant treatment of postmenopausal patients with early-stage breast cancer: a multicentre, open-label, randomised, phase 3 trial

BACKGROUND

The benefit of extending aromatase inhibitor therapy beyond 5 years in the context of previous aromatase inhibitors remains controversial. We aimed to compare extended therapy with letrozole for 5 years versus the standard duration of 2-3 years of letrozole in postmenopausal patients with breast cancer who have already received 2-3 years of tamoxifen.

METHODS

This multicentre, open-label, randomised, phase 3 trial was done at 69 hospitals in Italy. Women were eligible if they were postmenopausal at the time of study entry, had stage I-III histologically proven and operable invasive hormone receptor-positive breast cancer, had received adjuvant tamoxifen therapy for at least 2 years but no longer than 3 years and 3 months, had no signs of disease recurrence, and had an Eastern Cooperative Oncology Group performance status of 2 or lower. Patients were randomly assigned (1:1) to receive 2-3 years (control group) or 5 years (extended group) of letrozole (2·5 mg orally once a day). Randomisation, with stratification by centre, with permuted blocks of size 12, was done with a centralised, interactive, internet-based system that randomly generated the treatment allocation. Participants and investigators were not masked to treatment assignment. The primary endpoint was invasive disease-free survival in the intention-to-treat population. Safety analysis was done for patients who received at least 1 month of study treatment. This trial was registered with EudraCT, 2005-001212-44, and ClinicalTrials.gov, NCT01064635.

FINDINGS

Between Aug 1, 2005, and Oct 24, 2010, 2056 patients were enrolled and randomly assigned to receive letrozole for 2-3 years (n=1030; control group) or for 5 years (n=1026; extended group). After a median follow-up of 11·7 years (IQR 9·5-13·1), disease-free survival events occurred in 262 (25·4%) of 1030 patients in the control group and 212 (20·7%) of 1026 in the extended group. 12-year disease-free survival was 62% (95% CI 57-66) in the control group and 67% (62-71) in the extended group (hazard ratio 0·78, 95% CI 0·65-0·93; p=0·0064). The most common grade 3 and 4 adverse events were arthralgia (22 [2·2%] of 983 patients in the control group vs 29 [3·0%] of 977 in the extended group) and myalgia (seven [0·7%] vs nine [0·9%]). There were three (0·3%) serious treatment-related adverse events in the control group and eight (0·8%) in the extended group. No deaths related to toxic effects were observed.

INTERPRETATION

In postmenopausal patients with breast cancer who received 2-3 years of tamoxifen, extended treatment with 5 years of letrozole resulted in a significant improvement in disease-free survival compared with the standard 2-3 years of letrozole. Sequential endocrine therapy with tamoxifen for 2-3 years followed by letrozole for 5 years should be considered as one of the optimal standard endocrine treatments for postmenopausal patients with hormone receptor-positive breast cancer.

FUNDING

Novartis and the Italian Ministry of Health.

TRANSLATION

For the Italian translation of the abstract see Supplementary Materials section.

Toxicity of extended adjuvant endocrine with aromatase inhibitors in patients with postmenopausal breast cancer: A Systemtic review and Meta-analysis

BACKGROUND

Extended endocrine therapy (EET) with aromatase inhibitors (AIs) therapy can further reduce the risk of recurrence in breast cancer patients. But the conclusion that whether EET with AIs increases the risk of some side effects compared with nonextended endocrine therapy (NEET) is still controversial and not exhaustive.

METHODS

We searched for Randomized controlled trials (RCT) trials published in EMBASE and PubMed between March 2008 and December 2019. Studies comparing the side effects of adjuvant EET with those of NEET were included. The objective was to determine whether EET with AIs increases the risk of side effects compared with NEET.

RESULTS

Overall, 11 trials comprising 24,187 participants were identified. EET with AIs increased the risk of cardiotoxicity [odds ratio (OR) 1.19, 95 % confidence interval (CI) 1.04-1.36; P < 0.05; 438 vs 423], bone pain (OR 1.18, 95 % CI 1.02-1.36; P < 0.05; 446 vs 404), osteoporosis (OR 1.53, 95 % CI 1.35-1.72; P < 0.05; 866 vs 641), fractures (OR 1.33, 95 % CI 1.18-1.50; P < 0.05; 596 vs 438), arthralgia (OR 1.27, 95 % CI 1.19-1.36; P < 0.05; 2404 vs 2060), myalgia (OR 1.29, 95 % CI 1.16-1.43; P < 0.05; 960 vs 776), and hot flashes (OR 1.40, 95 % CI 1.15-1.69; P < 0.05; 2418 vs 2174) and was associated with opposite risk of vaginal bleeding (OR 0.74, 95 % CI 0.59-0.92; P < 0.05; 148 vs 197). However, the extended therapy did not increase the risk of hypertension (OR 1.03, 95 % CI 0.80-1.33; P = 0.80; 364 vs 353), hypercholesterolemia (OR 1.03, 95 % CI 0.91-1.16; P = 0.62; 643 vs 627), vaginal dryness (OR 1.19, 95 % CI 1.00-1.42; P = 0.05; 294 vs 257), fatigue (OR 1.20, 95 % CI 0.96-1.50; P = 0.12; 1501 vs 1462), dizziness (OR 1.04, 95 % CI 0.92-1.17; P = 0.55; 614 vs 595), headaches (OR 1.06, 95 % CI 0.95-1.18; P = 0.30; 885 vs 848), constipation (OR 0.91, 95 % CI 0.79-1.04; P = 0.15; 480 vs 522), nausea (OR 1.83, 95 % CI 0.49-6.83; P =0.37; 340 vs 325), and dyspnea (OR 0.96, 95 % CI 0.82-1.13; P = 0.64; 340 vs 351). The risk of grade ≥ 3 hot flashes increased following extended endocrine therapy (OR 2.01, 95 % CI 1.23-3.29; P < 0.05; 47 vs 23). We observed no evidence for a difference in the risk of grade ≥3 fatigue, arthralgia, myalgia, bone pain, osteoporosis, fractures, hypertension, and headache between both endocrine therapies. Secondary outcomes shows that after receive EET with AIs, patients can benefit from the control of the local recurrence, distant recurrence, contralateral breast cancer, and second cancers.

CONCLUSIONS

Compared with NEET, EET with AIs significantly increased the risk of cardiotoxicity, bone pain, osteoporosis, fractures, hot flashes, arthralgia, myalgia, and grade ≥3 hot flashes, and EET with AIs can reduced the risks of local recurrence, distant recurrence, contralateral breast cancer, and second cancers. These findings offer an important guide for clinicians and patients.