A yeast-based functional assay for the detection of the mutant androgen receptor in prostate cancer

OBJECTIVE

Mutations in the ligand-binding domain of the human androgen receptor (AR) figure among the ways used by prostate adenocarcinoma (PCa) cells to escape androgen dependence. These mutations may broaden the specificity and/or affinity of the AR to other hormones, resulting in inappropriate receptor activation and thus affecting the PCa response to physiological stimuli and hormonal therapies.

DESIGN

In order to clarify the impact of these mutations on disease progression and treatment, we have developed a yeast-based functional assay that allows the detection of mutant ARs and the analysis of their transactivation capacities in response to different ligands.

METHODS

AR cDNA was directly cloned into an expression vector in a yeast strain that carries a reporter gene (ADE2) linked to an androgen-dependent promoter. The expression of the ADE2 gene and consequently the yeast cell growth in a selective medium depleted in adenine depends on the specificity of the AR for the ligand added to the medium.

RESULTS

By analysing the transactivation capacities of different AR molecules in response to a broad range of steroid and non-steroid ligands, we have demonstrated that this assay can discriminate among wild-type AR, T877A, C685Y and L701H mutant ARs and that at least 1% of mutant ARs could be detected when mutant and wild-type ARs were mixed at the cDNA level.

CONCLUSIONS

The data presented here show that this simple AR assay is convenient for the routine detection of mutant ARs in PCa and is also suitable to evaluate the antagonist activities of anti-androgen molecules.

Resection of colorectal liver metastases with second-line aflibercept plus FOLFIRI: Results from the RESECTION prospective French cohort

AIM

To evaluate R0/R1 resection rate in patients with colorectal liver metastases (CLM) treated with aflibercept plus FOLFIRI after failure of a prior oxaliplatin-based regimen in daily clinical practice.

METHODS

This French, multicentre, prospective, observational cohort (NCT05178745) included patients with CLM (alone or predominant; up to 5 lung nodules <2 cm allowed) initiating aflibercept plus FOLFIRI every 2 weeks per physician choice. Primary endpoint was R0/R1 resection rate. Secondary endpoints included overall survival (OS), progression-free survival (PFS), radiological and pathological responses, and safety.

RESULTS

A total of 137 patients (median age 65 years, RAS/BRAF mutant 57 %/9 %) were enrolled at 22 French sites. CLM (median 4) were synchronous in 82 %, bilobar in 71 % and located in liver only in 54 %. Overall, 17 % of patients had R0/R1 resection (21 % for patients with liver-only disease). A major pathological response per Blazer score was observed in 55 % of resected patients, along with significantly longer OS (median 34.8 vs 9.1 months, p < 0.0001) and PFS (median 11.4 vs 4.9 months, p < 0.0001) compared to non-resected patients. Post-operative complications occurred in 17 % of patients (all Dindo-Clavien grade I-II) and there was no post-operative deaths. Overall, 34 % had grade ≥ 3 adverse events, mainly general health deterioration and diarrhea.

CONCLUSIONS

Results suggest that aflibercept plus FOLFIRI, after failure of a prior oxaliplatin-based regimen, allows R0/R1 resection of CLM in almost 20 % of patients with a major pathological response in most cases and a median OS prolonged by more than 3-fold versus non-resected patients.