Targeting FGFR pathway in breast cancer

Developments in breast cancer biology over the last years have permitted deconstructing the molecular profile of the most relevant breast cancer subtypes. This has led to an increase in therapeutic options, including more effective personalized therapy for breast cancer and substantial improvements in patient outcomes. Although currently there are only a few targeted therapies approved for metastatic breast cancer, the discovery of druggable kinase gene alterations has radically changed cancer treatment by providing novel and successfully actionable drug targets. Fibroblast growth factors and their receptors (FGFRs) participate in different physiologic processes and also play an essential role in cancer cell proliferation, survival, differentiation, migration, and apoptosis. This article summarizes the main molecular alterations of FGFRs, as well as the available preclinical and clinical data with FGFR inhibitors in breast cancer, and discusses new opportunities for the clinical development of these agents in patients with breast cancer.

Abstract OT1-03-06: LORELEI: A phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/ HER2-negative, early-stage breast cancer

Background: Taselisib is an orally bioavailable, potent, selective inhibitor of Class I PI3-kinase (PI3K) alpha, gamma, and delta isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the alpha isoform showing enhanced activity against PIK3CA mutant cancer cell lines. Clinical data have demonstrated confirmed partial responses in patients with PIK3CA mutant breast cancer (BC) treated with single-agent taselisib. Enhanced antitumor activity has been noted when taselisib is combined with either letrozole or fulvestrant in preclinical and Phase Ib clinical studies.

Methods: LORELEI is a Phase II, two-arm, randomized, double-blind, multicenter, study of neoadjuvant letrozole and taselisib versus letrozole and placebo in postmenopausal women with newly diagnosed ER+/HER2-, untreated, Stage I-III operable BC. Other eligibility criteria include tumor size  2 cm by magnetic resonance imaging (MRI), ECOG PS 0-1, and evaluable tumor tissue for PIK3CA genotyping. Patients treated with anti-diabetic drugs are not eligible. Patients are randomized (1:1) to receive continuous letrozole (2.5 mg) with either taselisib (4 mg on a 5 days on/ 2 days off schedule) or placebo for 16 weeks, followed by surgery. Stratification is based on tumor size and nodal status. The co-primary endpoints are overall objective response rate (ORR) by centrally assessed breast MRI via modified RECIST criteria and pathologic complete response (pCR) rate in breast and axilla at time of surgery in all randomized patients and PIK3CA mutant patients. Secondary endpoints include ORR by centrally-assessed MRI and pCR rate in PIK3CA wild-type patients. The sample size was calculated to detect an absolute percentage increase of 24% in ORR with 80% power and an absolute percentage increase of 18% in pCR rate. An interim safety analysis will be conducted by an Independent Data Monitoring Committee. As of 1st Jun 2015, 54 of the 330 patients have been enrolled, and global enrollment is ongoing (clinicaltrials.gov NCT02273973).

Contact information:

Reference Study ID Numbers: GO28888/BIG-3-13/SOLTI 1205/ABCSG 38

Phone: 888-662-6728 (US Only)

Email Address: global.rochegenentechtrials@roche.com

Citation Format: Oliveira M, de Azambuja E, Saura C, Dubsky P, Zardavas D, Fesl C, Bardia A, Soberino J, Ciruelos Gil E, Ng V, Fredrickson J, Stout TJ, Singel SM, Hsu JY, Piccart M, Gnant M, Baselga J. LORELEI: A phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/ HER2-negative, early-stage breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-06.

Abstract P4-09-02: Concordance in fibroblast growth factor receptor 1 (FGFR1) and 2 (FGFR2) status in breast cancer during tumor progression

BACKGROUND: In recent years, changes in HER2 and hormone receptor (HR) status between primary and metastatic breast cancer (BC) have been extensively reported. Additionally, current advances in BC biology have identified emerging biomarkers with clinical and prognostic implications, particularly the PI3K-AKT-mTOR and the FGF/FGFR pathways. FGFR1 and FGFR2 gene amplifications represent the most frequent genomic aberrations in BC. The 8p11-12 chromosomal region harboring the FGFR1 gene locus is amplified in about 10-18% of human BC, mainly in HR-positive/HER2-negative subtype, whereas the FGFR2 gene, located on chromosome 10q26, is amplified in approximately 4% of triple negative BC. To our knowledge, there is a lack of data regarding the concordance of FGFR1 and FGFR2 status between primary and metastatic tumors.

METHODS: Tumor samples from 205 and 67 advanced BC patients diagnosed at our institution between 2010 and 2014 were screened for FGFR1 and FGFR2 amplification by FISH using the ZytoLight SPEC FGFR1/CEN8 and FGFR2/CEN10 probes, respectively. FGFR1 and FGFR2 amplification were defined as a ratio of FGFR1/CEN8 and FGFR2/CEN10 ≥ 2.2. We investigated the correlation of FGFR1 and FGFR2 status between primary and metastatic tumors in 16 and 13 patients, respectively, for whom paired samples were available.

RESULTS: A total of 47 FGFR1-amplified patients (22.9%) and 3 FGFR2-amplified patients (4.5%) were identified. Patients with paired samples were classified according to FGFR1 and FGFR2 status in primary tumor. Regarding FGFR1 amplification, eight patients were FGFR1-amplified and eight were FGFR1-non-amplified. One patient in each group showed discordance in FGFR1 status in the metastatic tumor. Overall rate of concordance between primary and metastatic tumors was 87.5% (14/16). In relation to FGFR2 status, two patients were FGFR2-amplified and 11 were FGFR2-non-amplified with a 100% overall rate of concordance between paired samples (13/13). These data are summarized in Table 1.

Table 1  Metastases PrimaryAmplifiedNon-amplifiedFGFR1Amplified (n=8)71 Non-amplified (n=8)17FGFR2Amplified (n=2)20 Non-amplified (n=11)011

CONCLUSIONS: Results suggest a high concordance in FGFR1 and FGFR2 status between primary and metastatic BC. The potential impact of these findings on the development of FGFR inhibitors merits further investigation.

Citation Format: Zamora E, Aura C, Perez-Garcia J, Prudkin L, Meire A, Muñoz Cosuelo E, Jimenez J, Diaz-Delgado M, Ortega V, Soberino J, Farinas L, Salva F, Bellet M, Cruz C, Gomez P, Oliveira M, Vidal MJ, Saura C, Cortes J, Nuciforo P. Concordance in fibroblast growth factor receptor 1 (FGFR1) and 2 (FGFR2) status in breast cancer during tumor progression. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-09-02.

Abstract P2-08-13: Integrating multiplex and next generation sequencing (NGS) platforms in routine molecular profiling of metastatic breast cancer (MBC) patients (pts): Trends for enrollment in genotype-directed clinical trials (GDTs)

Background/aims: Multiplex or NGS platforms increase the number of mutations (mut) detected in tumor samples respect to single-gene sequencing techniques. We aimed to assess the actionable molecular alteration (ActMA) detection rate and the enrollment in GDTs derived from the integration of these platforms in routine molecular profiling of MBC pts, in addition to FISH and IHC techniques already in use. Methods: Consecutive MBC pts screened for gene mut by Sequenom (Seq) or AmpliconSeq (ASeq) were identified. Data on FGFR1 amplification (amp), PTEN IHC, and enrollment in GDTs were collected. ActMA: any mut, PTENnull (IHC score=0), or FGFR1/HER2amp for which a matched targeted drug might be available. Targeted therapy: treatment with PI3K/mTOR, novel anti-HER2, FGFR, or AKT inhibitors (inh) irrespective of having ActMA. GDT: treatment matched to ActMA. Results: From Oct2010-Apr2015, 260 pts screened (Seq 207, ASeq 53). IHC subtype: HR+/HER2- (LUM) 65%, HER2+ 13.5%, TN 19.6%, unk 1.9%. 84 samples from a metastatic site (32.3%).

ActMA / n (%)LUMHER2+TNP value (Fisher's exact test)TotalTP53*11 (31.4)1 (50)9 (52.9)0.3421 (38.9)PIK3CA44 (26)10 (28.6)4 (7.8)0.158 (22.7)FGFR1amp21 (17.4)1 (5.3)6 (16.7)0.4728 (15.9)PTENnull12 (9.3)2 (7.7)9 (25)0.0323 (12)AKT110 (5.9)1 (2.9)-0.1511 (4.3)ERBB23 (1.8)---3 (1.2)EGFR1 (0.6)-2 (4.1)-3 (1.2)ESR1*1 (3)---1 (2)KRAS2 (1.2)---2 (0.8)Denominators vary according to platform. *Amplicon only

Proportion of PIK3CAmut was similar irrespective of the site of analysis (primary 25.5%, metastasis 21.4%; P=0.63) and platform (Seq 22.2%, ASeq 24.5%, P=0.72). ASeq detected more mutations in actionable genes than Seq (36% vs. 29%, P=0.01). At least 1 ActMA (range 0-3) was found in 53.5% of pts, with non-significant differences in HER2- subtypes (LUM 48.5% vs. TN 39.2%, P=0.32).

Subtype* / ActMA n (%)≥10123All139 (53.5)121 (46.5)111 (42.7)25 (9.6)3 (1.2)LUM82 (48.5)87 (51.5)71 (42)9 (5.3)2 (1.2)HER2+35 (100)-22 (62.9)12 (34.3)1 (28)TN20 (39.2)31 (60.8)16 (31.4)4 (7.8)-*5 pts with unk subtype not shown

Pts with ≥2 ActMA (excluding HER2amp): 11 LUM (interestingly, 3 pts with PIK3CAmut+FGFR1amp), 1 HER2+, and 4 TN. Overall, 56% of pts received ≥1 targeted therapy (range 0-4). From the 139 pts with ≥1 potential ActMA (including HER2amp if treated with a novel anti-HER2), 61.8% received a targeted therapy and 42.4% were enrolled in a GDT: PI3K/mTOR inhibitor (inh) 54 (64.3%), novel anti-HER2 16 (19.1%), FGFR inh 8 (9.5%), AKT inh 6 (7.1%). Of the 121 pts that did not have potentially ActMA, 50% received a targeted therapy. The OR for receiving targeted therapy if ActMA was present was 1.59 (95%CI 0.94-2.70, P=0.08). Conclusion: Integration of multiplex and NGS platforms in routine molecular profiling of MBC pts yields a detection rate of ActMA >50%, which translates into higher probability of receiving a targeted agent and enrollment in a GDT. This suggests that physicians are pushing towards matched targeted therapies for pts that participate in molecular screening programs and have ActMA. Results on the outcome of these pts will be presented.

Citation Format: Oliveira M, Dienstmann R, Bellet M, Pérez-Garcia JM, Gómez P, Muñoz-Couselo E, Vidal M, Ortega V, Zamora E, Soberino J, Meire A, Nuciforo P, Vivancos A, Cortés J, Saura C. Integrating multiplex and next generation sequencing (NGS) platforms in routine molecular profiling of metastatic breast cancer (MBC) patients (pts): Trends for enrollment in genotype-directed clinical trials (GDTs). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-13.