Probes for INS

The fibroblast growth factor receptor FGFR2 is overexpressed in a variety of solid tumors, including breast, gastric and ovarian tumors, where it offers a potential therapeutic target. In this study, we present evidence of the preclinical efficacy of BAY 1187982, a novel antibody-drug conjugate (ADC). It consists of a fully human FGFR2 monoclonal antibody (mAb BAY 1179470), which is specific for the FGFR2 isoforms FGFR2-IIIb and FGFR2-IIIc, conjugated through a non-cleavable linker to a novel derivative of the microtubule-disrupting cytotoxic drug auristatin (FGFR2-ADC). In FGFR2-expressing cancer cell lines, this FGFR2-ADC exhibited potency in the low nM to sub-nM range and was more than 100-fold selective against FGFR2-negative cell lines. High expression levels of FGFR2 in cells correlated with efficient internalization, efficacy and cytotoxic effects in vitro. Pharmacokinetic analyses in mice bearing FGFR2-positive NCI-H716 tumors indicated that the toxophore metabolite of FGFR2-ADC was enriched more than 30-fold in tumors compared to healthy tissues. Efficacy studies demonstrated that FGFR2-ADC treatment leads to a significant tumor growth inhibition or tumor regression of cell line-based or patient-derived xenograft models of human gastric or breast cancer. Further, FGFR2 amplification or mRNA overexpression predicted high efficacy in both of these types of in vivo model systems. Taken together, our results strongly support the clinical evaluation of BAY 1187982 in cancer patients, and a Phase I study (NCT02368951) has been initiated.

Abstract

Pan-fibroblast growth-factor receptor (FGFR) inhibitors hold promise in FGFR-altered patients, but such alterations are rare in advanced urothelial carcinoma. In order to assess whether we may increase the number of eligible patients by using different molecular techniques for detecting alterations, we pooled the results of the centralised FGFR mutation/translocation assays that were performed in Clinical Laboratory Improvement Amendments-certified laboratories within multiple phase 2 trials. At our centre, the same tissue blocks were used to analyse FGFR1-3 messenger RNA expression through messenger RNA in situ hybridisation (ISH; RNAscope 2.5 assay). From October 2016 to March 2017, 52 cases were analysed. Seventeen patients (32.7%) had an upper tract primary tumour. Ten patients (19.2%) had FGFR DNA alterations. Twenty-nine (55.8%) had positive ISH analysis: N=17 score 3, N=12 score 4. Of note, concordance between the two tests was obtained in seven out of 10 patients. Sixty percent of mutated patients had an upper tract primary tumour versus 31% of ISH-positive patients.

PATIENT SUMMARY:

We found three-fold higher frequency of fibroblast growth-factor receptor alterations at the RNA versus DNA level in advanced urothelial carcinoma, with a different distribution according to the method used and the site of the primary tumour. The evaluation of the therapeutic response to pan-fibroblast growth-factor receptor inhibitors according to the method of assessment is warranted.

Abstract

Background

Fibroblast growth factor receptor (FGFR2) has been proposed as a target in gastric cancer. However, appropriate methods to select patients for anti-FGFR2 therapies have not yet been established.

Methods

We used in situ techniques to investigate FGFR2 mRNA expression and gene amplification in a large cohort of 1036 Japanese gastric cancer patients. FGFR2 mRNA expression was determined by RNAscope. FGFR2 gene amplification was determined by dual-color in situ hybridization (DISH).

Results

We successfully analyzed 578 and 718 samples by DISH and RNAscope, respectively; 2% (12/578) showed strong FGFR2 gene amplification (FGFR2:CEN10 >10); moderate FGFR2gene amplification (FGFR2:CEN10 <10; ≥2) was detected in 8% (47/578); and high FGFR2 mRNA expression of score 4 (>10 dots/cell and >10% of positive cells with dot clusters under a 20× objective) was seen in 4% (29/718). For 468 samples, both mRNA and DISH data were available. FGFR2 mRNA expression levels were associated with gene amplification; FGFR2 mRNA levels were highest in the highly amplified samples (n = 12). All highly amplified samples showed very strong FGFR2 mRNA expression (dense clusters of the signal visible under a 1× objective). Patients with very strong FGFR2 mRNA expression showed more homogeneous FGFR2 mRNA expression compared to patients with lower FGFGR2 mRNA expression. Gastric cancer patients with tumors that had an FGFR2 mRNA expression score of 4 had shorter RFS compared with score 0–3 patients.

Conclusion

RNAscope and DISH are suitable methods to evaluate FGFR2 status in gastric cancer. Formalin-fixed paraffin-embedded (FFPE) tissue slides allowed evaluation of the intratumor heterogeneity of these FGFR2 biomarkers.

Abstract

OBJECTIVES:

Metastatic colorectal cancer (CRC) remains a leading cause of cancer related deaths. Patients with oligometastatic liver disease represent a clinical subgroup with heterogeneous course. Until now, biomarkers to characterize outcome and therapeutic options have not been fully established.

METHODS:

We investigated the prevalence of FGFR alterations in a total of 140 primary colorectal tumors and 63 liver metastases of 55 oligometastatic CRC patients. FGF receptors (FGFR1-4) and their ligands (FGF3, 4 and 19) were analyzed for gene amplifications and rearrangements as well as for RNA overexpression in situ. Results were correlated with clinico-pathologic data and molecular subtypes.

RESULTS:

Primary tumors showed FGFR1 (6.3%) and FGF3,4,19 (2.2%) amplifications as well as FGFR1 (10.1%), FGFR2 (5.5%) and FGFR3 (16.2%) overexpression. In metastases, we observed FGFR1 amplifications (4.8%) as well as FGFR1 (8.5%) and FGFR3 (14.9%) overexpression. Neither FGFR2-4 amplifications nor gene rearrangements were observed. FGFR3 overexpression was significantly associated with shorter overall survival in metastases (mOS 19.9 vs. 47.4 months, HR=3.14, p=0.0152), but not in primary CRC (HR=1.01, p=0.985). Although rare, also FGFR1 amplification was indicative of worse outcome (mOS 12.6 vs. 47.4 months, HR=8.83, p=0.00111).

CONCLUSIONS:

We provide the so far most comprehensive analysis of FGFR alterations in primary and metastatic CRC. We describe FGFR3 overexpression in 15% of CRC patients with oligometastatic liver disease as a prognosticator for poor outcome. Recently FGFR3 overexpression has been shown to be a potential therapeutic target. Therefore, we suggest focusing on this subgroup in upcoming clinical trials with FGFR-targeted therapies.