Abstract 4290
Background
The phosphatidylinositol 3-kinase (PI3K) pathway plays a central role in cell proliferation and survival in human cancer. Mutations in PIK3CA, the gene coding the p110α catalytic subunit of PI3K, are frequent in cancer and result in PI3K pathway activation. About 25% of HER2-positive breast cancers also carry PIK3CA mutations, known to confer resistance to anti-HER2 therapy. Here we report the preclinical characterization of MEN1611, a potent and selective orally available PI3K inhibitor, showing high activity against p110α mutant isoforms and sparing the δ isoform.
Methods
In vivo efficacy studies were evaluated through Tumour Volume Inhibition % (TVI%) and mRECIST criteria using cancer cell lines and patient-derived xenograft (PDX) models. Pathway activation and protein degradation analyses were performed by western blot and capillary electrophoresis immunoassay. Immune modulation was evaluated using murine macrophages differentiated in vitro.
Results
Consistent with its mechanism of action, MEN1611 down-modulates the PI3K/AKT signaling as well as selected downstream targets, both in vitro and in vivo. MEN1611 acts synergistically when combined with trastuzumab in several HER2-positive PIK3CA-mutated breast cancer cell lines and patient-derived xenograft models. The in vivo efficacy in trastuzumab-resistant models is supported by a long-lasting antitumor activity, paralleled by mechanistic down-regulation of pharmacodynamic biomarkers. Moreover, MEN1611 showed the ability to induce a dose-dependent alpha-isoform depletion, and to modulate the macrophage polarization towards a pro-inflammatory phenotype, consistent with its capability to co-inhibit P110γ.
Conclusions
Overall, these preclinical data support the progression in the development of MEN1611 in breast cancer and pave the way to the B-Precise-01 clinical study, a multicentre phase Ib study.
Clinical trial identification
NCT03767335.
Editorial acknowledgement
Legal entity responsible for the study
Menarini Ricerche S.p.A.
Funding
Menarini Ricerche S.p.A.
Disclosure
A. Fiascarelli: Full / Part-time employment: Menarini RIcerche S.p.A. G. Merlino: Full / Part-time employment: Menarini Ricerche S.p.A. S. Capano: Full / Part-time employment: Menarini Ricerche S.p.A. A. Paoli: Full / Part-time employment: Menarini Ricerche S.p.A.. A. Bressan: Full / Part-time employment: Menarini Ricerche. M. Bigioni: Full / Part-time employment: Menarini Ricerche S.p.A.. M. Scaltriti: Advisory / Consultancy: Memorial Sloan-Kettering Cancer Center. J. Arribas: Advisory / Consultancy: Vall d’Hebron Institute of Oncology. C. Bernadó Morales: Advisory / Consultancy: Vall d’Hebron Institute of Oncology. A. Pellacani: Leadership role, Full / Part-time employment: Menarini Ricerche S.p.A.. M. Salerno: Leadership role, Full / Part-time employment: Menarini Ricerche. M. Binaschi: Leadership role, Full / Part-time employment: Menarini Ricerche S.p.A.
Resources from the same session
4370 - Continental differences in pathologic response with neoadjuvant ipilimumab (IPI) plus nivolumab (NIVO) in patients with macroscopic stage III melanoma in the phase 2 OpACIN-neo trial.
Presenter: Irene Reijers
Session: Poster Display session 3
Resources:
Abstract
3230 - Comparable responses of melanoma at primary site and synchronous lymph node metastases upon neoadjuvant ipilimumab (IPI) and nivolumab (NIVO)
Presenter: Judith Versluis
Session: Poster Display session 3
Resources:
Abstract
3171 - Adjuvant Therapies for Stage III Melanoma: Benchmarks for Bringing Clinical Trials to Clinical Practice
Presenter: Tina HIEKEN
Session: Poster Display session 3
Resources:
Abstract
3493 - Mixture-cure modeling for resected stage III/IV melanoma in the phase 3 CheckMate 238 trial
Presenter: Jeffrey Weber
Session: Poster Display session 3
Resources:
Abstract
3036 - An open-label, non-randomized, phase IIIb study of trametinib in combination with dabrafenib for patients with unresectable advanced BRAFV600-mutant melanoma: a subgroup analysis of patients with brain metastasis
Presenter: Caroline Dutriaux
Session: Poster Display session 3
Resources:
Abstract
2233 - Adverse event (AE) kinetics in patients (pts) treated with dabrafenib + trametinib (D + T) in the metastatic and adjuvant setting
Presenter: Jean Jacques Grob
Session: Poster Display session 3
Resources:
Abstract
2435 - A Single Arm, Open Label, Phase II, Multicenter Study to Assess the Detection of the BRAF V600 Mutation on cfDNA from Plasma in Patients with Advanced Melanoma
Presenter: Piotr Rutkowski
Session: Poster Display session 3
Resources:
Abstract
1766 - Efficacy and Safety of Dabrafenib and Trametinib in Patients with Metastatic BRAFV600 Mutation-positive Melanoma in the Real-World Setting – Interim results of the non-interventional COMBI-r study
Presenter: Carola Berking
Session: Poster Display session 3
Resources:
Abstract
2131 - Trial update: A randomized Phase Ib/II study of the selective small molecule Axl inhibitor Bemcentinib (BGB324) in combination with either dabrafenib/trametinib (D/T) or pembrolizumab in patients with metastatic melanoma
Presenter: Oddbjørn Straume
Session: Poster Display session 3
Resources:
Abstract
4074 - Analysis of pyrexia in patients (pts) treated with dabrafenib (D) and/or trametinib (T) across clinical trials
Presenter: Caroline Robert
Session: Poster Display session 3
Resources:
Abstract