Gefitinib Plus Chemotherapy vs Gefitinib Alone in Untreated EGFR-Mutant Non-Small Cell Lung Cancer in Patients With Brain Metastases: The GAP BRAIN Open-Label, Randomized, Multicenter, Phase 3 Study

First-line zorifertinib for EGFR-mutant non-small cell lung cancer with central nervous system metastases: The phase 3 EVEREST trial

BACKGROUND

Zorifertinib (AZD3759), an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) with high blood-brain barrier penetration capability, demonstrated promising intracranial and systemic antitumor activity in phase 1 and 2 studies in central nervous system (CNS)-metastatic patients.

METHODS

In this phase 3 EVEREST trial (ClinicalTrials.gov: NCT03653546), patients with EGFR-sensitizing mutations, advanced treatment-naive non-small cell lung cancer (NSCLC), and non-irradiated symptomatic or asymptomatic CNS metastases were randomized (1:1) to zorifertinib or first-generation EGFR-TKI (gefitinib or erlotinib; control). The primary endpoint was blinded independent central review (BICR)-assessed progression-free survival (PFS) per RECIST1.1.

FINDINGS

Overall, 439 patients were randomized (zorifertinib n = 220; control n = 219). Most patients had the EGFR L858R mutation (55%) or >3 CNS lesions (54%). Median PFS was significantly longer with zorifertinib versus control (9.6 versus 6.9 months; hazard ratio [HR], 0.719; 95% confidence interval [CI], 0.580-0.893; p = 0.0024). Zorifertinib significantly prolonged intracranial PFS versus control (BICR per modified RECIST1.1: HR, 0.467; 95% CI, 0.352-0.619; investigator per RANO-BM: HR, 0.627; 95% CI, 0.466-0.844). Overall survival (OS) was immature; the estimated median OS was 37.3 months with zorifertinib and 31.8 months with control (HR, 0.833; 95% CI, 0.524-1.283) in patients subsequently treated with third-generation EGFR-TKIs. Safety profiles were consistent with previously reported data for zorifertinib.

CONCLUSIONS

Zorifertinib significantly improved systemic and intracranial PFS versus first-generation EGFR-TKIs; adverse events were manageable. Sequential use of zorifertinib and third-generation EGFR-TKIs showed the potential to prolong patients' survival. The results favor zorifertinib as a novel, well-validated first-line option for CNS-metastatic patients with EGFR-mutant NSCLC.

FUNDING

This work was funded by Alpha Biopharma (Jiangsu) Co., Ltd., China.

First-line treatment of EGFR-mutated non-small cell lung cancer with brain metastases: a systematic review and meta-analysis

This systematic review and network meta-analysis evaluates first-line treatment options for patients with EGFR-mutant non-small cell lung cancer (NSCLC) and brain metastases. We analyzed 24 randomized controlled trials (RCTs) involving 2,682 patients, comparing various EGFR tyrosine kinase inhibitors (TKIs) and combination therapies. Direct comparisons showed that the addition of bevacizumab or chemotherapy to first-generation (1G) EGFR-TKIs improved overall survival (OS) compared to 1G TKIs alone, with HRs of 0.704 (95% CI: 0.433-0.973) and 0.682 (95% CI: 0.464-0.899), respectively. However, third-generation (3G) TKI monotherapy did not significantly improve OS compared with 1G TKIs, with an HR of 0.855 (95% CI: 0.511-1.198). Indirect comparisons suggested that the combination of 3G TKIs with chemotherapy provided the most significant improvements in OS and progression-free survival (PFS), significantly outperforming 3G TKIs, with HRs of OS 1.69 (95% CI: 1.14-3.4) and PFS 2.13 (95% CI: 1.28-3.54). Intracranial PFS was best with 1G TKIs plus bevacizumab. Our findings suggest that 3G EGFR-TKIs in combination with chemotherapy may be the most effective strategy for patients with EGFR-mutant NSCLC and brain metastases, though further head-to-head trials are needed for validation.

Top advances of the year: Targeted therapy for lung cancer

The past year has offered significant advancements in the field of non-small cell lung cancer (NSCLC), both in the early and advanced disease settings. The identification of guideline-recommended actionable targets has provided the foundation for developing multiple new therapeutic agents. There has been a focus on developing drugs designed to overcome acquired resistance, a limitation of tyrosine kinase inhibitor-based therapy in lung cancer. In addition, there is an emerging trend toward combination therapies for patients in the first-line setting with the goal of preventing or delaying resistance. Another promising area of development has been the use of antibody-drug conjugates, where there are the initial reports of central nervous system efficacy and activity in patients with genomic alterations. Over the past year, numerous publications and presentations have highlighted multiple therapeutic advances, offering new treatment options for patients with NSCLC. The focus of this review is to summarize the most impactful findings, emphasizing their significance in the evolving treatment landscape for NSCLC. Several landmark trials in lung cancer with practice-changing clinical implications have been presented and published in 2023. This article reviews a selection of these trials as they relate to early and advanced-stage oncogene-driven lung cancer. The ADAURA and ALINA trials, in which targeted therapy given in the adjuvant setting has demonstrated improved clinical outcomes, are reviewed. In the advanced-stage setting, recent trials in the context of specific oncogene drivers are reviewed, including EGFR, ALK, ROS1, RET, ERBB2 (HER2), BRAF, MET exon 14 skipping (METex14), and KRAS alterations. Also discussed are the results of several trials that have evaluated the use of combination therapies and resistance-mechanism agnostic treatment strategies. PLAIN LANGUAGE SUMMARY: Targeted therapy plays an important role for patients with early and advanced-stage non-small cell lung cancer carrying specific genetic alterations. New strategies that combine multiple therapies are now being studied in randomized clinical trials, with the goal of enhancing the effectiveness of targeted therapy for patients with advanced lung cancer.

Current pharmacologic treatment of brain metastasis in non-small cell lung cancer

Lung cancer is a type of cancer that can metastasize to the lungs, brain, bones, liver, adrenal glands, and other organs; however, the occurrence of brain metastases is the most common event. Symptoms of brain metastasis include motor dysfunction, mental dysfunction, seizures, headaches, nausea, and vomiting, and significantly reduce the quality of life of cancer patients. Brain metastases are a poor prognostic factor, and controlling them is extremely important for prolonging prognosis and improving the quality of life. Currently, local surgery and radiotherapy are recommended for their treatment. However, recently, cancer treatments using molecular-targeted drugs and immune checkpoint inhibitors have been introduced, which may also be effective against brain metastases. Therefore, it is necessary to determine whether local or systemic therapy is optimal for each case. In this review, we focus on recent findings regarding drug therapy in treating brain metastases from advanced non-small cell lung cancer.

Strategies and influencing factors for the treatment of advanced non-small cell lung cancer based on epidermal growth factor receptor tyrosine kinase inhibitors: a narrative review

Background and Objective

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the primary treatment for advanced non-small cell lung cancer (NSCLC) patients with EGFR mutations, significantly enhancing patient prognosis. Despite the efficacy of EGFR-TKIs, monotherapy faces challenges such as variability among individuals and early drug resistance. This article aims to explore the treatment strategies and influencing factors for advanced NSCLC patients treated with EGFR-TKIs, optimize treatment plans, and improve the prognosis of patients with advanced NSCLC.

Methods

We undertook a comprehensive, narrative review of the latest literature to define the current application and progress of EGFR-TKIs in treating patients with advanced NSCLC.

Key Content and Findings

The efficacy and promise of EGFR-TKIs, both as monotherapy and combined with other agents, for treating patients with advanced NSCLC are outlined. The study delves into the mechanisms of resistance and the ongoing development of EGFR-TKIs. Various factors influencing the treatment of advanced NSCLC patients with EGFR-TKIs are also examined.

Conclusions

EGFR-TKIs alone improve survival in patients with advanced NSCLC. Combined with other agents, some regimens have shown improved benefits in overcoming drug resistance and prolonging patient survival. It is imperative to focus on developing novel EGFR-TKIs and investigate innovative combination therapies to maximize patient benefit.

Real world results of locally advanced and metastatic lung cancer patients treated with platinum doublet chemotherapy in first line: Moroccan cohort

BACKGROUND

Doublet platin-chemotherapy was the old standard treatment for different histology types of advanced and metastatic lung cancer (LC) and is still an option for patients who are not eligible for immune checkpoint inhibitors. However, in low- and middle-income countries, chemotherapy, either in monotherapy or in combination with platinum, is still the only accessible option in public institutions. The efficacy of different platin-based chemotherapy in patients with LC who are treatment-naïve is unknown.

METHODS

In this retrospective study, we selected patients with advanced and metastatic (IIIB-IVB) non-squamous non-small cell LC (NSCLC), squamous NSCLC, and lung neuroendocrine tumours (small cell LC (SCLC), large cell neuroendocrine, and atypical carcinoid) aged beyond 18 years who received first-line chemotherapy (docetaxel, gemcitabine, etoposide, paclitaxel, pemetrexed, and vinorelbine) combined with platinum between January 1, 2013, and December 31, 2022. Within the population with non-squamous NSCLC, squamous NSCLC, and neuroendocrine tumours, progression-free survival (PFS) and overall survival (OS) were the primary assessed endpoints. Hematologic safety was the secondary endpoint.

RESULTS

Overall, 611 patients were included. In the group of patients with non-squamous NSCLC (n = 390), there was no statistical difference between subgroups of patients who received first-line platin-chemotherapy. The median PFS was 182 (95 % confidence interval [CI], 167-208) days (hazard ratio for progression: NR [Not Reached]; p = 0.37), and the median OS was 446 (95 % CI, 405-559) days (hazard ratio for death: 1.31; 95 % CI, 0.94 - 1.82; p = 0.1). In the group of patients with squamous NSCLC (n = 149), we note the absence of statistical significance between subgroups of patients who received platin-based chemotherapy. The median PFS was 195 (95 % CI, 142-238; hazard ratio for progression: 1.21, 95 % CI, 0.29-5.02; p = 0.27), while the median OS was 428 (95 % CI, 324-940) days (hazard ratio for death: 1.76; 95 % CI, 0.93 to 3.3; p = 0.32). The absence of significance has been noticed in the neuroendocrine subgroup of patients who received first etoposide-platinum, vinorelbine-platinum, or paclitaxel-platinum (n = 72). The median PFS was 216 (95 % CI, 193-277) days; hazard ratio for progression: 1.74, 95 % CI, 0.41-7.27; p = 0.69, while the median OS was 273 (95 % CI, 241-459) days (hazard ratio for death: 2.95; 95 % CI, 0.4-21.7; p = 0.51). Grade 3-4 neutropenia grade was the predominant adverse event associated with chemotherapy in almost 11 % of patients.

CONCLUSION

Moving forward, treatment strategies must be refined for patients, with an emphasis on increasing the number of patients who can benefit from emergent approaches in order to guarantee a wider, deeper, and longer-lasting outcome.

First-line concomitant EGFR-TKI + chemotherapy versus EGFR-TKI alone for advanced EGFR-mutated NSCLC: a meta-analysis of randomized phase III trials

INTRODUCTION

A tyrosine-kinase inhibitor (TKI) is indicated as a first-line treatment for patients with non-small-cell lung cancer (NSCLC) harboring an epidermal growth-factor - receptor (EGFR) mutation. Chemotherapy (ChT) given in combination with an EGFR-TKI in this setting is of interest.

METHODS

We conducted a meta-analysis of phase III randomized trials comparing EGFR-TKI + ChT vs. EGFR-TKI alone as first-line therapy for advanced NSCLC harboring an activating EGFR mutation.

RESULTS

Three studies evaluated gefitinib + ChT (NEJ009, GAP-Brain, and Noronha et al.) and another evaluated osimertinib + ChT (FLAURA-2). Those four eligible studies included 1413 patients with non-squamous NSCLCs, 826 (58%) with an exon-19 deletion (ex19del) and 541 (38%) with EGFRL858R. The EGFR-TKI + ChT combination was significantly associated with prolonged PFS (hazard ratio [HR]: 0.52 [95% confidence interval (CI): 0.45-0.59]; p < 0.0001) and OS (HR: 0.69 [0.52-0.93]; p = 0.01). PFS was particularly improved for patients with brain metastases (HR: 0.41[0.33-0.51]; p < 0.00001).

CONCLUSIONS

For patients with untreated, advanced, EGFR-mutated NSCLCs, the EGFR-TKI + ChT combination, compared to EGFR-TKI alone, was associated with significantly prolonged PFS and OS. However, further studies are needed to identify which patients will benefit the most from the combination.

REGISTRATION

PROSPERO CRD42024508055.

Clinical characteristics and MRI based radiomics nomograms can predict iPFS and short-term efficacy of third-generation EGFR-TKI in EGFR-mutated lung adenocarcinoma with brain metastases

BACKGROUND

Predicting short-term efficacy and intracranial progression-free survival (iPFS) in epidermal growth factor receptor gene mutated (EGFR-mutated) lung adenocarcinoma patients with brain metastases who receive third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy was of great significance for individualized treatment. We aimed to construct and validate nomograms based on clinical characteristics and magnetic resonance imaging (MRI) radiomics for predicting short-term efficacy and intracranial progression free survival (iPFS) of third-generation EGFR-TKI in EGFR-mutated lung adenocarcinoma patients with brain metastases.

METHODS

One hundred ninety-four EGFR-mutated lung adenocarcinoma patients with brain metastases who received third-generation EGFR-TKI treatment were included in this study from January 1, 2017 to March 1, 2023. Patients were randomly divided into training cohort and validation cohort in a ratio of 5:3. Radiomics features extracted from brain MRI were screened by least absolute shrinkage and selection operator (LASSO) regression. Logistic regression analysis and Cox proportional hazards regression analysis were used to screen clinical risk factors. Single clinical (C), single radiomics (R), and combined (C + R) nomograms were constructed in short-term efficacy predicting model and iPFS predicting model, respectively. Prediction effectiveness of nomograms were evaluated by calibration curves, Harrell's concordance index (C-index), receiver operating characteristic (ROC) curves and decision curve analysis (DCA). Kaplan-Meier analysis was used to compare the iPFS of high and low iPFS rad-score patients in the predictive iPFS R model and to compare the iPFS of high-risk and low-risk patients in the predictive iPFS C + R model.

RESULTS

Overall response rate (ORR) was 71.1%, disease control rate (DCR) was 91.8% and median iPFS was 12.67 months (7.88-20.26, interquartile range [IQR]). There were significant differences in iPFS between patients with high and low iPFS rad-scores, as well as between high-risk and low-risk patients. In short-term efficacy model, the C-indexes of C + R nomograms in training cohort and validation cohort were 0.867 (0.835-0.900, 95%CI) and 0.803 (0.753-0.854, 95%CI), while in iPFS model, the C-indexes were 0.901 (0.874-0.929, 95%CI) and 0.753 (0.713-0.793, 95%CI).

CONCLUSIONS

The third-generation EGFR-TKI showed significant efficacy in EGFR-mutated lung adenocarcinoma patients with brain metastases, and the combined line plot of C + R can be utilized to predict short-term efficacy and iPFS.

CNS Efficacy of Osimertinib With or Without Chemotherapy in Epidermal Growth Factor Receptor-Mutated Advanced Non-Small-Cell Lung Cancer

PURPOSE

We report CNS efficacy of first-line osimertinib plus chemotherapy versus osimertinib monotherapy in patients with epidermal growth factor receptor (EGFR)-mutated advanced non-small-cell lung cancer (NSCLC) from the phase III FLAURA2 study according to baseline CNS metastasis status.

METHODS

Patients were randomly assigned to osimertinib plus platinum-pemetrexed (combination) or osimertinib monotherapy until disease progression or discontinuation. Brain scans were performed in all patients at baseline and progression and at scheduled assessments until progression for patients with baseline CNS metastases; scans were assessed by neuroradiologist CNS blinded independent central review (BICR).

RESULTS

On the basis of baseline CNS BICR, 118 of 279 (combination) and 104 of 278 (monotherapy) randomly assigned patients had ≥one measurable and/or nonmeasurable CNS lesion and were included in the CNS full analysis set (cFAS); 40 of 118 and 38 of 104 had ≥one measurable target CNS lesion and were included in the post hoc CNS evaluable-for-response set (cEFR). In the cFAS, the hazard ratio (HR) for CNS progression or death was 0.58 (95% CI, 0.33 to 1.01). In patients without baseline CNS metastases, the HR for CNS progression or death was 0.67 (95% CI, 0.43 to 1.04). In the cFAS, CNS objective response rates (ORRs; 95% CI) were 73% (combination; 64 to 81) versus 69% (monotherapy; 59 to 78); 59% versus 43% had CNS complete response (CR). In the cEFR, CNS ORRs (95% CI) were 88% (73 to 96) versus 87% (72 to 96); 48% versus 16% had CNS CR.

CONCLUSION

Osimertinib plus platinum-pemetrexed demonstrated improved CNS efficacy compared with osimertinib monotherapy, including delaying CNS progression, irrespective of baseline CNS metastasis status. These data support this combination as a new first-line treatment for patients with EGFR-mutated advanced NSCLC, including those with CNS metastases.

First-line chemoimmunotherapy and immunotherapy in patients with non-small cell lung cancer and brain metastases: a registry study

Introduction

Brain metastases commonly occur in patients with non-small cell lung cancer (NSCLC). Standard first-line treatment for NSCLC, without an EGFR, ALK or ROS1 mutation, is either chemoimmunotherapy or anti-PD-1 monotherapy. Traditionally, patients with symptomatic or untreated brain metastases were excluded from the pivotal clinical trials that established first-line treatment recommendations. The intracranial effectiveness of these treatment protocols has only recently been elucidated in small-scale prospective trials.

Methods

Patients with NSCLC and brain metastases, treated with first-line chemoimmunotherapy or anti-PD-1 monotherapy were selected from the Australian Registry and biObank of thoracic cancers (AURORA) clinical database covering seven institutions. The primary outcome was a composite time-to-event (TTE) outcome, including extracranial and intracranial progression, death, or need for local intracranial therapy, which served as a surrogate for disease progression. The secondary outcome included overall survival (OS), intracranial objective response rate (iORR) and objective response rate (ORR).

Results

116 patients were included. 63% received combination chemoimmunotherapy and 37% received anti-PD-1 monotherapy. 69% of patients received upfront local therapy either with surgery, radiotherapy or both. The median TTE was 7.1 months (95% CI 5 - 9) with extracranial progression being the most common progression event. Neither type of systemic therapy or upfront local therapy were predictive of TTE in a multivariate analysis. The median OS was 17 months (95% CI 13-27). Treatment with chemoimmunotherapy was predictive of longer OS in multivariate analysis (HR 0.35; 95% CI 0.14 - 0.86; p=0.01). The iORR was 46.6%. The iORR was higher in patients treated with chemoimmunotherapy compared to immunotherapy (58% versus 31%, p=0.01). The use of chemoimmunotherapy being predictive of iORR in a multivariate analysis (OR 2.88; 95% CI 1.68 - 9.98; p=0.04).

Conclusion

The results of this study of real-world data demonstrate the promising intracranial efficacy of chemoimmunotherapy in the first-line setting, potentially surpassing that of immunotherapy alone. No demonstrable difference in survival or TTE was seen between receipt of upfront local therapy. Prospective studies are required to assist clinical decision making regarding optimal sequencing of local and systemic therapies.

Clinical significance of TP53 alterations in advanced NSCLC patients treated with EGFR, ALK and ROS1 tyrosine kinase inhibitors: An update

 The development of targeted therapies for non-small cell lung cancer (NSCLC), such as the epidermal growth factor receptor (EGFR), anaplastic lymphoma receptor tyrosine kinase (ALK), and ROS proto-oncogene 1 (ROS1), has improved patients' prognosis and significantly extended progression-free survival. However, it remains unclear why some patients do not benefit from the treatment as much or have a rapid disease progression. It is considered that, apart from the oncogenic driver gene, molecular alterations in a number of caretaker and gatekeeper genes significantly impact the efficacy of targeted therapies. The tumor protein 53 (TP53) gene is one of the most frequently mutated genes in NSCLC. To date, numerous studies have investigated the influence of various TP53 alterations on patient prognosis and responsiveness to therapies targeting EGFR, ALK, or ROS1. This review focuses on the latest data concerning the role of TP53 alterations as prognostic and/or predictive biomarkers for EGFR, ALK, and ROS1 tyrosine kinase inhibitors (TKIs) in advanced NSCLC patients. Since the presence of TP53 mutations in NSCLC has been linked to its decreased responsiveness to EGFR, ALK, and ROS1 targeted therapy in most of the referenced studies, the review also discusses the impact of TP53 mutations on treatment resistance. It seems plausible that assessing the TP53 mutation status could aid in patient stratification for optimal clinical decision-making. However, drawing meaningful conclusions about the clinical value of the TP53 co-mutations in EGFR-, ALK- or ROS1-positive NSCLC is hampered mainly by an insufficient knowledge regarding the functional consequences of the TP53 alterations. The integration of next-generation sequencing into the routine molecular diagnostics of cancer patients will facilitate the detection and identification of targetable genetic alterations along with co-occurring TP53 variants. This advancement holds the potential to accelerate understanding of the biological and clinical role of p53 in targeted therapies for NSCLC.

Management of Brain Metastases: A Review of Novel Therapies

Brain metastases (BMs) represent the most common intracranial tumors in adults, and most commonly originate from lung, followed by breast, melanoma, kidney, and colorectal cancer. Management of BM is individualized based on the size and number of brain metastases, the extent of extracranial disease, the primary tumor subtype, neurological symptoms, and prior lines of therapy. Until recently, treatment strategies were limited to local therapies, like surgical resection and radiotherapy, the latter in the form of whole-brain radiotherapy or stereotactic radiosurgery. The next generation of local strategies includes laser interstitial thermal therapy, magnetic hyperthermic therapy, post-resection brachytherapy, and focused ultrasound. New targeted therapies and immunotherapies with documented intracranial activity have transformed clinical outcomes. Novel systemic therapies with intracranial utility include new anaplastic lymphoma kinase inhibitors like brigatinib and ensartinib; selective "rearranged during transfection" inhibitors like selpercatinib and pralsetinib; B-raf proto-oncogene inhibitors like encorafenib and vemurafenib; Kirsten rat sarcoma viral oncogene inhibitors like sotorasib and adagrasib; ROS1 gene rearrangement (ROS1) inhibitors, anti-neurotrophic tyrosine receptor kinase agents like larotrectinib and entrectinib; anti-human epidermal growth factor receptor 2/epidermal growth factor receptor exon 20 agent like poziotinib; and antibody-drug conjugates like trastuzumab-emtansine and trastuzumab-deruxtecan. This review highlights the modern multidisciplinary management of BM, emphasizing the integration of systemic and local therapies.

ESCRT-III Component CHMP4C Attenuates Cardiac Hypertrophy by Targeting the Endo-Lysosomal Degradation of EGFR

BACKGROUND

Cardiac hypertrophy and subsequent heart failure impose a considerable burden on public health worldwide. Impaired protein degradation, especially endo-lysosome-mediated degradation of membrane proteins, is associated with cardiac hypertrophy progression. CHMP4C (charged multivesicular body protein 4C), a critical constituent of multivesicular bodies, is involved in cellular trafficking and signaling. However, the specific role of CHMP4C in the progression of cardiac hypertrophy remains largely unknown.

METHODS

Mouse models with CHMP4C knockout or cardiadc-specific overexpression were subjected to transverse aortic constriction surgery for 4 weeks. Cardiac morphology and function were assessed through histological staining and echocardiography. Confocal imaging and coimmunoprecipitation assays were performed to identify the direct target of CHMP4C. An EGFR (epidermal growth factor receptor) inhibitor was administrated to determine whether effects of CHMP4C on cardiac hypertrophy were EGFR dependent.

RESULTS

CHMP4C was significantly upregulated in both pressure-overloaded mice and spontaneously hypertensive rats. Compared with wild-type mice, CHMP4C deficiency exacerbated transverse aortic constriction-induced cardiac hypertrophy, whereas CHMP4C overexpression in cardiomyocytes attenuated cardiac dysfunction. Mechanistically, the effect of CHMP4C on cardiac hypertrophy relied on the EGFR signaling pathway. Fluorescent staining and coimmunoprecipitation assays confirmed that CHMP4C interacts directly with EGFR and promotes lysosome-mediated degradation of activated EGFR, thus attenuating cardiac hypertrophy. Notably, an EGFR inhibitor canertinib counteracted the exacerbation of cardiac hypertrophy induced by CHMP4C knockdown in vitro and in vivo.

CONCLUSIONS

CHMP4C represses cardiac hypertrophy by modulating lysosomal degradation of EGFR and is a potential therapeutic candidate for cardiac hypertrophy.