Phase III trial of sunitinib (SU) in combination with capecitabine (C) versus C in previously treated advanced breast cancer (ABC)

LBA1011

Background: Recent trials support combining an antiangiogenic agent with chemotherapy (CT) in pretreated patients (pts) with metastatic BC (MBC). SU, an oral multitargeted tyrosine kinase inhibitor demonstrated single-agent activity (11% ORR) in heavily pretreated pts with MBC. Antitumor activity with SU+C was reported in pts with advanced solid tumors. This multicenter, randomized, phase III trial (SUN 1099) compared the efficacy and safety of SU + C vs. C in pts with ABC.

Methods: Eligibility criteria were: age ≥18 yrs, ECOG PS ≤1, measurable HER2-positive (FISH+, CISH+ or IHC3+) or -negative ABC, no brain metastases, prior treatment (tx) with an anthracycline and taxane in the (neo)adjuvant or metastatic setting, and ≤2 prior CT regimens for advanced disease. Prior C tx was not permitted. Pts were randomized (1:1) to combination tx with C 2,000 mg/m2/d po days 1–14 every q3w + SU 37.5 mg/d po daily, or to C 2,500 mg/m2/d days 1–14 q3w. Pts with progressive disease per RECIST on the C arm were offered single-agent SU (37.5 mg/d). Endpoints included PFS (primary), ORR, OS, QoL, and safety. Stratified and unstratified log-rank tests compared PFS between arms.

Results: At the data cutoff (December 15, 2009), the ITT population comprised 442 pts: 221 in each arm with baseline characteristics well balanced between arms. The trial did not meet its primary endpoint of prolonging PFS based on the independent radiologic assessment nor secondary endpoint of longer OS (final analysis March 10, 2010). Median PFS was 5.5 mos (95% CI 4.5–6.0) in the SU+C arm vs. 5.9 mos (95% CI 5.4–7.6) in the C arm (HR 1.224). Median OS was 16.4 mos (95% CI 13.6–18.4) for the SU+C arm and 16.5 mos (95% CI 14.2–18.6) for the C arm (HR 0.995). ORR was 18.6% for the SU+C arm and 16.3% for the C arm. The most common all causality grade 3/4 AEs (≥10%) were neutropenia (32%), hand–foot syndrome (HFS; 16%), thrombocytopenia (17%), asthenia (12%), fatigue (10%) in the SU+C arm and HFS (24%) and diarrhea (10%) in the C arm. Intended drug delivery for each arm was >80%. Discontinuations due to an AE were more frequent in the SU+C arm vs. the C arm. Discontinuations by drug in the SU+C arm: SU 39%, C 42%, SU and C 33%; in the C arm: 18%.

Conclusions: Data from this randomized phase III trial do not support use of SU+C for therapy of patients with ABC.

[Table: see text]

Prospects for non-immunological molecular therapeutics in melanoma

In 2006 there were 60,000 new cases of cutaneous melanoma in the European Union and 13,000 deaths (www.europeancancerleagues. org). Currently available systemic treatment options for metastatic melanoma, including both cytotoxic and immunologic therapies, produce low rates of response and have modest survival impact. Therefore, there is an urgent need for effective novel therapies. Molecularly targeted treatments have demonstrated efficacy in certain cancers e.g. in HER2- positive breast cancer and in chronic myeloid leukaemia. Several pathways are currently being investigated as potential molecular targets in melanoma. The best studied is BRAF which is frequently mutated in melanoma. A multi tyrosine kinase inhibitor, sorafenib, which targets BRAF, has shown promising activity in preclinical studies and is currently being tested in combination with chemotherapy in patients with metastatic disease. In addition to BRAF, therapies which target other components of the Raf/Ras/MAPK pathway are being investigated. Other novel targets currently being investigated include the PI3/AKT pathway, tyrosine kinases, angiogenesis, poly (ADP ribose) polymerases, survivin and heat shock protein 90. Progress on preclinical and clinical evaluation of these novel targets in melanoma will be reviewed.

Combining HSP90 Inhibition with Standard Therapies for HER2 Positive Breast Cancer

Background: HSP90 is required for the stability and activity of HER2 and downstream proteins, such as Akt, which play a key role in cell survival. We aimed to assess the anti-tumor effects of the HSP90 inhibitor NVP-AUY922 in HER-2 positive breast cancer cell lines.Methods: HER2 positive breast cancer cell lines with varied sensitivity to trastuzumab (Sensitive: BT474, SKBR3, MDA-MB-361; acquired resistance: BT474Res, SKBR3Res; innate resistance: HCC1419, HCC1954, MDA-MB-453) were treated with the HSP90 inhibitor NVP-AUY922 (Novartis) and trastuzumab. IC50s were determined using the acid phosphatase assay. HER2, Akt and HSP90 levels were determined by immunoblotting after treatment with NVP-AUY922. Combinations of NVP-AUY922 with trastuzumab were tested in BT474, BT474Res, SKBR3, SKBR3Res, HCC1954, and MDA-MB-361 cells. Combinations with docetaxel, cisplatin and 5'-deoxy-5-fluorouridine (5-DFUR) were tested in BT474, SKBR3, HCC1954, MDA-MB-453 and MDA-MB-361 cells.Results: All of the HER2 positive cells were sensitive to NVP-AUY922, with IC50s ranging from 5.5 to 16.4 nM and NVP-AUY922 treatment reduced HER2 and Akt levels in a dose dependent manner. Combined treatment with NVP-AUY922 (10 nM) and trastuzumab (10 nM) showed significantly greater inhibition of growth than either trastuzumab or NVP-AUY922 alone in BT474 and BT474Res cell lines (p<0.005). In SKBR3, SKBR3Res, HCC1954, MDA-MB-453 and MDA-MB-361 cells, dual treatment with NVP-AUY922 and trastuzumab did not significantly increase response compared to NVP-AUY922 alone (Table 1). Combinations of docetaxel, cisplatin or 5-DFUR with NVP-AUY922 were antagonistic in all cell lines tested (CI values >1).Conclusions: This study demonstrates that NVP-AUY922 has anti-tumour activity in HER2 positive breast cancers regardless of sensitivity to trastuzumab. The antagonistic interactions observed for combinations of NVP-AUY922 with chemotherapy do not favour clinical evaluation of concurrent administration of NVP-AUY922 with chemotherapy. However, alternative scheduling or combinations with other targeted therapies warrants further investigation.Table 1: Percentage growth in response to NVP-AUY922 and trastuzumab. BT474BT474ResSKBR3SKBR3ResHCC1954MDA-MB-361Trastuzumab53.3 +/- 4.990.4 +/- 7.669.5 +/- 16.179.5 +/- 8.2102.9 +/- 15.558.4 +/- 3.3AUY92255.0 +/- 1.192.6 +/- 11.933.3 +/- 9.719.1 +/- 6.152.2 +/- 13.88.2 +/- 6.2Tras+AUY92222.0 +/- 2.3*59.7 +/- 17.5*30.6 +/- 7.518.3 +/- 4.347.2 +/- 3.42.5 +/- 2.2 

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5055.

Preliminary Phase II Data Suggest That Entinostat (SNDX275), a Class 1 Selective Histone Deacetylase Inhibitor (HDACi), May Resensitize Breast Cancer Patients Progressing on Aromataste Inhibitor (AI) Therapy to Their AI Therapy

Background: Aromatase inhibitors (AI), reduce peripheral conversion of androgen to estrogen, and are standard treatment for ER+ breast cancer (BCA); however, despite initial benefit, the disease eventually progresses. Once patients become resistant to AI, cytotoxic chemotherapy is often used for palliation. Histone deacetylase inhibitors (HDACi) have been shown preclinically to reverse AI resistance and sensitize tumor to AI. Entinostat, an oral selective HDACi, reverses both de novo and acquired hormone resistance in BCA in cell lines and xenograph models and has been well-tolerated, in humans, as a single agent and in combination with other agents tested to date.Methods: Postmenopausal women with ER+ BCA progressing while receiving AI for > 3 months were enrolled. Eligibility criteria included: measurable disease by RECIST criteria, PS 0 or 1, and ≤ 1 chemotherapy for metastatic disease. Exclusion criteria included: rapidly-progressing BCA, life-threatening metastases, chemotherapy within 3 months, and previous exposure to epigenetic modulating agents. Patients continued the AI therapy on which the cancer was progressing, with the addition of entinostat 5 mg weekly in 28-day cycles. Primary objective was to determine clinical benefit rate during the first 6 cycles, defined as the proportion of patients achieving CR, PR or SD lasting > 6 months. Secondary objectives included ORR and PFS. Exploratory biomarkers for anti-tumor activities and entinostat pharmacology were also measured.Results: To date, 24 patients have been enrolled from October 2008 – May 2009. Interim results from 20 patients are described here. The median age is 69 yrs. Eight (40%) and 12 (60%) patients had ECOG scores of 0 and 1, respectively. Fifteen patients (80%) had received tamoxifen; 12 (60%) had prior chemotherapy or immunotherapy. Nine patients (45%) had visceral involvement (lung, pleura, and liver), and 10 had metastases to bone, 3 to breast, and 1 to skin. Among the 10 patients who have completed ≥ 2 cycles, preliminary analysis indicates that the longest durations of SD thus far are > 6 months in 1 and > 5 months in 2 patients. Preliminary analysis of biomarkers in paired samples from 6 patients indicates that HDAC inhibition correlates with changes in cellular molecular targets. Entinostat has been well-tolerated. The majority of AEs were mild to moderate in severity, and the character of AEs was generally consistent with that seen with AI therapy.Conclusion: Entinostat in combination with AI was well-tolerated in patients with progressive BCA. Disease stabilization in several patients was observed. At dose administered, expected pharmacological effects were achieved.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6111.

TMEM25, REPS2 and Meis 1: favourable prognostic and predictive biomarkers for breast cancer

BACKGROUND/AIMS

A panel of prognostic and predictive biomarkers would contribute to personalized treatment of breast cancer patients. However, many such biomarkers have yet to be identified and evaluated. The aim of this study was to investigate the relevance of 3 such putative biomarkers.

METHODS

TMEM25, REPS2 and Meis 1 expression was investigated by qRT-PCR, in triplicate, in 103 breast tumour biopsies procured in 1993-1994. Normal breast tissue specimens were also analysed for comparative purposes. Univariate and multivariate analyses were used to identify associations between expression of these transcripts as well as patients' clinicopathological and survival data.

RESULTS

TMEM25, REPS2 and Meis 1 transcripts were detected in approximately 52, 78 and 40% of tumour specimens, respectively. Expression of each of the 3 genes was indicative of extended survival times from diagnosis [association between relapse-free survival (RFS) and TMEM25, p = 0.0002; REPS2, p = 0.0287; association between overall survival (OS) and TMEM25, p = 0.001; REPS2, p = 0.0131; Meis 1, p = 0.0255]. Presence of TMEM25 and Meis 1 was associated with oestrogen receptor-positive (TMEM25, p < 0.0005; Meis 1, p = 0.011), lower-grade (TMEM25, p = 0.002; Meis 1, p = 0.001) tumours. Multivariate analysis indicated TMEM25 expression to be an independent prognostic factor for extended RFS (p = 0.011) and OS (p = 0.001). Furthermore, for patients who received adjuvant chemotherapy, significantly longer survival times were achieved if their tumours expressed TMEM25 (OS, p = 0.031; RFS, p = 0.0181) and REPS2 (OS, p = 0.011). While expression of these mRNAs was generally absent from triple-negative breast tumours, statistical significance was not achieved.

CONCLUSION

Our results suggest that TMEM25, REPS2 and Meis 1 mRNAs may be useful members of a panel of favourable prognostic and predictive markers for breast cancer and an understanding of their function may provide useful information about this disease.

Phase I evaluation of lapatinib (L) and epirubicin (E) in patients (pts) with anthracycline (anth)-naive metastatic breast cancer (MBC)

1107

Background: HER-2 alteration confers enhanced anth sensitivity in MBC, although HER-2 is not a target for anth. Topoisomerase 2A (Topo) is a target for anth. Topo amplification has been reported to occur only with HER-2 amplification, in approximately 1/3 of HER-2 amplified BC, providing a rationale for anth + trastuzumab(H) therapy in MBC with co-ampified HER-2/Topo. T+anth is cardiotoxic. L may have similar single agent activity, but less cardiotoxicity than H. L competes with anth for p-glycoprotein and might enhance its activity. The cardiac safety of L + anth needed to be established. Methods: We conducted a phase I evaluation of fixed dose lapatinib (1250 mg/day) with escalating doses of epirubicin (Epi-planned dose levels I-IV :75/80/90/100 mg/m2 ) in pts with HER-2±, anth-naive metastatic BC. Epirubicin was administered q3 weeks. A minimum of 3 (if no dose-limiting toxicity) and a maximum of 6 pts were treated per dose level. Ejection fractions were performed at base line and after every second cycle; BNP and troponin after every cycle. Results: 9 pts were treated, 3 level I, 6 level II. Dose level I was declared the maximum tolerated dose following two occurrences of dose-limiting toxicity in level II. 1 pt experienced febrile neutropenia,1 had > 20% decrease in LVEF. To date there have been 3 PRs by RECIST out of 8 evaluable patients which represents a response rate of 37.5%. Conclusions: Using classic phase I criteria, the combination of L 1250 mg together with Epi 75 mg/m2 combination is relatively well tolerated and suitable for further investigation in a phase II study of HER-2+veTopo+ve MBC patients. We will conduct such a study in pts with HER-2+Topo+ metastatic BC.

[Table: see text]

Activity of dasatinib with chemotherapy in triple-negative breast cancer cells

e14605

Background: Triple-negative breast cancers (TNBC) lack expression of oestrogen, progesterone, and are HER-2 normal. TNBC cell lines have displayed greater sensitivity to growth inhibition by the multi-target kinase inhibitor, dasatinib, than luminal or HER- 2 positive breast cancer cell lines. The aim of this study was to assess the direct anti-tumor effects of dasatinib in combination with chemotherapy in TNBC. Methods: Four TNBC cell lines (MDA-MB-231, HCC-1143, HCC-1937, MDA-MB-468) were treated with dasatinib in combination with docetaxel, cisplatin or 5'-5' DFUR. IC50 values were calculated for each drug alone by determining response in a 5-day proliferation (acid phosphatase) assay. Combination index (CI) values were determined, using CalcuSyn, to assess the interaction between drugs. Results: Three of the cell lines (MDA-MB-231, HCC- 1143, HCC-1937) were sensitive to dasatinib (IC50 < 1 μM) whereas MDA-MB-468 was resistant (IC50 > 1 μM) (Table). In MDA-MB-231 and HCC-1143 cells, combined treatment with dasatinib and 5'-5'-DFUR displayed synergy (CI<1.0), whereas the combination was additive in HCC-1937 cells (CI=0.98). Combined treatment with dasatinib and cisplatin was synergistic in the three dasatinib sensitive cell lines (CI<1.0). Dasatinib in combination with docetaxel displayed moderate synergy in MDA-MB-231 and HCC-1937 cells (CI<1.0), but was antagonistic in HCC-1143 cells (CI>1.0). Conclusions: Our findings show that the combination of dasatinib with either 5'-5'-DFUR or cisplatin is synergistic in TNBC cell lines, and suggest that combinations of dasatinib with chemotherapy may improve response in triple negative breast cancer patients. [Table: see text]

No significant financial relationships to disclose.

HSP90 inhibition in HER2-positive breast cancer cells

e14573

Background: HSP90 is required for the stability and activity of HER2 and downstream proteins, such as Akt, which play a key role in survival. We aimed to assess the anti-tumor effect of the HSP90 inhibitor NVP-AUY922 in HER-2 positive breast cancer cell lines. Methods: HER2 positive breast cancer cell lines with varied sensitivity to trastuzumab (Sensitive: BT474, SKBR3; acquired resistance: BT474Res, SKBR3Res; innate resistance: HCC1419, HCC1954, MDA-MB-453) were treated with the HSP90 inhibitor NVP-AUY922 (Novartis) and trastuzumab. IC50s were determined using the acid phosphatase assay. HER2, Akt and HSP90 levels were determined by immunoblotting after treatment with NVP-AUY922. Combinations of NVP-AUY922 with docetaxel, cisplatin and 5'-deoxy-5-fluorouridine (5-DFUR) were tested in BT474 and SKBR3 cells. Results: All of the HER2 positive cells were sensitive to NVP-AUY922, with IC50s ranging from 5.5 to 16.4 nM. Combined treatment with NVP-AUY922 (10 nM) and trastuzumab (10 nM) showed significantly greater inhibition of growth than either trastuzumab or NVP-AUY922 alone in BT474 and BT474Res cell lines (p<0.005). In SKBR3 and SKBR3Res cells, dual treatment with NVP-AUY922 and trastuzumab did not significantly increase response compared to NVP-AUY922 alone ( Table 1 ). Treatment with NVP-AUY922 resulted in a dose-dependent decrease in HER2 and Akt levels in trastuzumab-sensitive and -resistant cells. Combinations of docetaxel, cisplatin or 5-DFUR with NVP- AUY922 were antagonistic in both BT474 and SKBR3 cells (CI values >1). Conclusions: This study demonstrates that NVP-AUY922 has anti-tumor activity in trastuzumab-sensitive, and in both innate and acquired trastuzumab-resistant HER2 positive breast cancer cells. The antagonistic interactions observed for combinations of NVP-AUY922 with chemotherapy do not favour clinical evaluation of such combinations. However, combinations with other targeted therapies, such as trastuzumab, warrant further investigation.

[Table: see text]

[Table: see text]

HER-2 signaling and inhibition in breast cancer

Amplification of the HER-2 gene occurs in approximately 25% of breast cancers, causing up-regulation of key signaling pathways which control cell growth and survival. In breast cancer patients, HER-2 overexpression correlates with an aggressive phenotype and poor prognosis. HER-2, therefore, has become the focus of many anti-cancer therapeutic approaches. Trastuzumab (Herceptin), a humanized monoclonal antibody directed against the extracellular domain of HER-2, was the first FDA-approved HER-2-targeted therapy for the treatment of metastatic breast cancer. However, not all HER-2-overexpressing patients respond to trastuzumab and most that initially respond develop resistance within one year of treatment. Trastuzumab resistance has been studied in cell line models of resistance and several mechanisms of resistance have been proposed. More recent anti-HER-2 strategies involve targeting its tyrosine kinase domain; for example, lapatinib (Tykerb) is a dual HER-2 and EGFR tyrosine kinase inhibitor and has shown efficacy as a single agent and in combination with other therapeutics. A number of novel HER-2 antagonists are currently in preclinical or clinical development, including both monoclonal antibodies and small molecule inhibitors. Increased understanding of HER-2 signaling in breast cancer, and of response and resistance to HER-2 antagonists, will aid the development of strategies to overcome resistance to HER-2 targeted therapies.

Epidermal growth factor receptor as a potential therapeutic target in triple-negative breast cancer

BACKGROUND

No proven targeted therapy is currently available for the treatment of triple-negative breast cancer (TNBC). Epidermal growth factor receptor (EGFR) is frequently overexpressed in TNBC. We studied the activity of EGFR antagonists alone, and in combination with chemotherapy, in TNBC cell lines.

MATERIALS AND METHODS

EGFR and phosphorylated EGFR were measured by enzyme-linked immunosorbent assay. Sensitivity to EGFR inhibitors alone and in combination with chemotherapy was assessed. Effects of gefitinib on EGFR signalling and cell cycle were also examined.

RESULTS

EGFR was overexpressed in the TNBC compared with the human epidermal growth factor receptor 2 (HER-2)-positive cell lines. Phosphorylation of EGFR was detected in the TNBC cells in response to epidermal growth factor stimulation and was blocked by gefitinib treatment. However, the TNBC cell lines were less sensitive to EGFR inhibition than the HER-2-positive cell lines. Response to gefitinib was associated with reduced phosphorylation of both mitogen activated protein kinase (MAPK) and Akt and induction of G(1) arrest. Gefitinib enhanced response to both carboplatin and docetaxel in the TNBC cells, and the triple combination of gefitinib, carboplatin and docetaxel was synergistic.

CONCLUSIONS

Although the TNBC cells are less sensitive to EGFR inhibition than the HER-2-positive cell lines, gefitinib enhanced response to chemotherapy. Gefitinib combined with carboplatin and docetaxel warrants further investigation in TNBC.

ADAM-17 predicts adverse outcome in patients with breast cancer

ADAM-17 is a matrix metalloproteinase-like enzyme involved in the release of several ligands that have been shown to promote both cancer formation and progression. These ligands include transforming growth factor-alpha, amphiregulin, heparin-binding epidermal growth factor, epiregulin and tumor necrosis factor-alpha. In this investigation, we measured the expression of total ADAM-17 by enzyme-linked immunosorbent assay in 153 invasive breast cancers. We also measured the precursor and active forms by western blotting in 140 invasive breast cancers. Expression of ADAM-17 was significantly increased in high-grade compared with low-grade tumors and was independent of tumor size, lymph node metastasis and estrogen receptor status. Patients with high expression of ADAM-17 had a significantly shorter overall survival compared with those with low expression. Significantly, the prognostic impact of ADAM-17 was independent of conventional prognostic factors for breast cancer. Our results are further evidence that ADAM-17 is involved in breast cancer progression and thus provides further impetus for exploiting ADAM-17 as new target for cancer treatment.