Current Status of CRISPR/Cas9 Application in Clinical Cancer Research: Opportunities and Challenges

Cancer is considered by not only multiple genetic but also epigenetic amendments that drive malignant cell propagation and consult chemo-resistance. The ability to correct or ablate such mutations holds enormous promise for battling cancer. Recently, because of its great efficiency and feasibility, the CRISPR-Cas9 advanced genome editing technique has been extensively considered for therapeutic investigations of cancers. Several studies have used the CRISPR-Cas9 technique for editing cancer cell genomic DNA in cells and animal cancer models and have shown therapeutic potential in intensifying anti-cancer protocols. Moreover, CRISPR-Cas9 may be used to correct oncogenic mutations, discover anticancer drugs, and engineer immune cells and oncolytic viruses for immunotherapeutic treatment of cancer. We herein discuss the challenges and opportunities for translating therapeutic methods with CRISPR-Cas9 for clinical use and suggest potential directions of the CRISPR-Cas9 system for future cancer therapy.

A phase I/II study of epertinib plus trastuzumab with or without chemotherapy in patients with HER2-positive metastatic breast cancer

BACKGROUND

Epertinib (S-222611) is a potent reversible inhibitor of HER2, EGFR and HER4. This trial evaluated the safety, tolerability, pharmacokinetics and antitumour activity of daily oral epertinib combined with trastuzumab (arm A), with trastuzumab plus vinorelbine (arm B) or with trastuzumab plus capecitabine (arm C), in patients with HER2-positive metastatic breast cancer (MBC).

METHODS

Eligible patients, with or without brain metastases, had received prior HER2-directed therapy. A dose-escalation phase determined the tolerability of each combination and established a dose for further study. Further, patients were recruited to expansion cohorts in each of the 3 arms to further explore efficacy and safety.

RESULTS

The recommended doses of epertinib were 600 mg, 200 mg and 400 mg in arms A, B and C, respectively. The most frequent grade 3/4 adverse event (AE) was diarrhoea in all arms, which was manageable with medical intervention and dose modification. The objective response rate (complete response [CR] plus partial response [PR]) in heavily pre-treated HER2-positive MBC patients at the recommended doses of epertinib combined with trastuzumab was 67% (N = 9), with trastuzumab plus vinorelbine was 0% (N = 5) and with trastuzumab plus capecitabine was 56% (N = 9). Notably, 4 of 6 patients previously treated with T-DM1 responded in the arm A expansion cohort (epertinib plus trastuzumab). In the arm C expansion cohort (epertinib plus trastuzumab plus capecitabine), 4 of 7 patients responded despite previous exposure to capecitabine. Measurable regression of brain metastases was observed in patients with CNS target lesions treated in both arms A and C.

CONCLUSION

We observed safety, tolerability and encouraging antitumour activity of epertinib combined with trastuzumab, or with trastuzumab plus capecitabine. This supports further evaluation of these combinations in patients with pre-treated HER2-positive MBC, with or without brain metastases.

TRIAL REGISTRATION

EudraCT Number: 2013-003894-87; registered 09-September-2013.

Randomized phase II trial of venetoclax + fulvestrant versus fulvestrant in estrogen receptor+, HER2– locally advanced or metastatic breast cancer following recurrence or progression during or after a CDK4/6 inhibitor: VERONICA

TPS1108

Background: CDK4/6 inhibitors (CDK4/6is) administered with endocrine therapy have demonstrated improvements in progression-free survival (PFS) for estrogen receptor (ER)+ advanced breast cancer (BC), but resistance occurs, and new options are needed in the post-CDK4/6i setting. BCL2 is an estrogen-responsive anti-apoptotic molecule overexpressed in 75% of BCs. The BCL2 inhibitor venetoclax (Ven) has shown improved outcomes and tolerability in hematological malignancies such as chronic lymphocytic leukemia, and has been investigated in BC. A phase 1b study of Ven + tamoxifen demonstrated safety and an efficacy signal in ER+, BCL2+ metastatic BC (mBC). Preclinical data for Ven + fulvestrant (Ful) have also shown synergy. Based on these proof-of-principle data, the current study evaluates safety and efficacy of Ven + Ful vs Ful in women with ER+, HER2– locally advanced (LA)/mBC progressing after first- or second-line of prior therapy for metastatic disease, including ≥8 wks of a CDK4/6i. Methods: VERONICA is a global, randomized, phase 2, multicenter, open-label study. Eligible patients (pts) are aged ≥18 yrs with confirmed ER+, HER2–, inoperable LA/mBC, ≥1 measurable lesion, tissue evaluable for BCL2, and ECOG performance status 0–1. Prior Ful or Ven, or prior chemotherapy for LA/mBC are prohibited. Stratified by BCL2 expression (low vs high) and number of prior lines of mBC therapy (1 vs 2), pts are randomized 1:1 to Ven 800 mg PO daily + Ful 500 mg IM (cycle 1 days 1 and 15, and day 1 of each subsequent 28-day cycle) vs Ful 500 mg IM alone. Treatment continues until disease progression or intolerable toxicity. Primary endpoint is clinical benefit rate defined as complete/partial response + stable disease for ≥24 wks from randomization. Secondary efficacy endpoints include PFS, objective response rate, duration of response, and overall survival. Safety, pharmacokinetic, biomarker (e.g. BCL2 and PI3K expression) and patient-reported outcome analyses will also be conducted. Currently, 21 of the planned 100 pts have been enrolled; enrollment is ongoing. Clinical trial information: NCT03584009.

BGCS uterine cancer guidelines: Recommendations for practice

The British Gynaecological Cancer Society has issued the first Endometrial (Uterine) Cancer guidelines as recommendation for practice for the UK.

Phase I, Dose-Escalation, Two-Part Trial of the PARP Inhibitor Talazoparib in Patients with Advanced Germline BRCA1/2 Mutations and Selected Sporadic Cancers

Talazoparib inhibits PARP catalytic activity, trapping PARP1 on damaged DNA and causing cell death in BRCA1/2-mutated cells. We evaluated talazoparib therapy in this two-part, phase I, first-in-human trial. Antitumor activity, MTD, pharmacokinetics, and pharmacodynamics of once-daily talazoparib were determined in an open-label, multicenter, dose-escalation study (NCT01286987). The MTD was 1.0 mg/day, with an elimination half-life of 50 hours. Treatment-related adverse events included fatigue (26/71 patients; 37%) and anemia (25/71 patients; 35%). Grade 3 to 4 adverse events included anemia (17/71 patients; 24%) and thrombocytopenia (13/71 patients; 18%). Sustained PARP inhibition was observed at doses ≥0.60 mg/day. At 1.0 mg/day, confirmed responses were observed in 7 of 14 (50%) and 5 of 12 (42%) patients with BRCA mutation-associated breast and ovarian cancers, respectively, and in patients with pancreatic and small cell lung cancer. Talazoparib demonstrated single-agent antitumor activity and was well tolerated in patients at the recommended dose of 1.0 mg/day.Significance: In this clinical trial, we show that talazoparib has single-agent antitumor activity and a tolerable safety profile. At its recommended phase II dose of 1.0 mg/day, confirmed responses were observed in patients with BRCA mutation-associated breast and ovarian cancers and in patients with pancreatic and small cell lung cancer. Cancer Discov; 7(6); 620-9. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 539.

Abstract P4-21-08: A phase I/II of S-222611, a reversible EGFR and HER2 inhibitor, combined with trastuzumab +/- chemotherapy in patients with HER2-positive metastatic breast cancer

Background: S-222611, an oral, reversible EGFR and HER2 inhibitor, has been shown to be well-tolerated as monotherapy at a dose of 800mg daily with good anti-tumor activity in patients previously treated with other anti-HER2-based regimens. This study evaluated the tolerability and safety of daily oral administration of S-222611 (S) in combination with trastuzumab (T), trastuzumab + vinorelbine (T+V) and trastzumab + capecitabine (T+C) in HER2-positive (HER2+) metastatic breast cancer (MBC) with or without brain metastases.

Methods: This study was performed as a 3+3 dose escalation followed by expansion to examine the tolerability and safety of S in combination with T, T+V and T+C in Arms A, B and C, respectively. S was administered orally once daily, starting at a dose of 400mg in Arm A, and 200mg in Arms B and C. The dosing of T was 8mg/kg loading followed by 6mg/kg or fixed dose of 600mg subcutaneously every 21 days as recommended. V was administered at 60mg/m2 orally on Day 1 and 8 of a 21-day cycle, and C 1000mg/m2 orally daily for 14 days followed by a 7-day rest period. All patients had HER2+ MBC and were required to have progressed following at least one prior line of anti-HER2 therapy. Prior treatments with V and C were permitted. Anti-diarrhea prophylaxis with loperamide was not required.

Results: A total of 45 patients were enrolled. All patients had received prior anti-tumor regimens including T (n=45), T-DM1 (n=26), pertuzumab (n=9) and lapatinib (n=12). The clinically recommended doses of S at which most adverse events were manageable,were determined as:600mg in Arm A, 200mg in Arm B and 400mg in Arm C. Dose limiting toxicities included Grade 3 diarrhea for Arm A; and Grade 4 neutropenia, Grade 3 Hypokalemia and Hypophosphatemia for Arm B. As of 13 May 2016, treatment is ongoing in 2 patients. No other Grade 4 AEs related to S-222611 have been observed. Grade 3 bilirubin elevation was observed in 5/45 patients, probably due to transporter (UGT1A1) inhibition, while no G3/4 liver dysfunction was reported. RECIST partial responses (PR) were observed in 6 of 9 patients in Arm A and 5 of 9 patients in Arm C, at respective clinically recommended doses. Nine of 45 patients had brain metastases; 4 of these patients showed RECIST PR including an intracranial tumor response in one patient (400mg in Arm C) who had prior treatments with paclitaxel, T+C, T-DM1 and V after diagnosis of BM.

Conclusions: The clinically recommended doses of S-222611 combined with T, T +V and T+C were determined for further clinical studies. Clinical benefit (PR and SD >6 month) was seen with each combination even in heavily pre-treated HER2+ MBC patients.

Summary of the safety and efficacy of S-222611 (S) combination. Dose (mg)nDLT (1st cycle)G3 Diarrhea during study (N of patients)RECIST tumor response, PR n/ SD ≥6M nORR n (%)CBR n (%)Arm A: S + T4005010/10/5 (0%)1/5 (20%)Arm A: S + T6009036/06/9 (67%)6/9 (67%)Arm A: S + T8007141/11/7 (14%)2/7 (29%)Arm B: S + T + V2005020/40/5 (0%)4/5 (80%)Arm B: S + T + V4002211/01/2 (50%)1/2 (50%)Arm C: S + T + C2004010/10/4 (0%)1/4 (25%)Arm C: S + T + C4009025/05/9 (56%)5/9 (56%)Arm C: S + T + C6004022/12/4 (50%)3/4 (75%)

Citation Format: Rafii S, Macpherson I, Baird R, Saggese M, Spiliopoulou P, Kumar S, Italiano A, Bonneterre J, Campone M, Cresti N, Posner J, Takeda Y, Arimura A, Spicer J. A phase I/II of S-222611, a reversible EGFR and HER2 inhibitor, combined with trastuzumab +/- chemotherapy in patients with HER2-positive metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-08.

BRAF +/- MEK inhibition in patients (pts) with BRAF-mutant (mut) metastatic colorectal cancer (mCRC): The Sarah Cannon Research Institute UK’s experience

645

Background: Activating V600 BRAF mutations are detectable in around 10% of mCRC pts and are associated with poor prognosis. Low response rates have been reported with anti-BRAF monotherapy in this subset of pts while encouraging data exist on enhanced MAPK pathway inhibition with combination therapy (anti-BRAF + anti-MEK and/or anti-EGFR). Methods: We performed a pooled analysis of BRAF-mut mCRC pts enrolled into different phase 1 trials involving the use of anti-BRAF monotherapy alone (Group A) or in combination with a MEK inhibitor (Group B) at therapeutic doses between June 2012 and August 2016. Demographic, baseline, toxicity and efficacy data were retrospectively reviewed. Results: Twenty BRAF-mut mCRC pts were identified in either Group A (n = 13) or Group B (n = 7). All pts had an ECOG performance status ≤ 1. Median age was 54 years (range 33-74). The primary tumor was right-sided in 10 (50%) pts, left-sided in 9 (45%) pts, and unknown in 1 (5%) subject. Median number of previous treatment lines was 1 (range 1-4). The disease control rate was 55%, with 3 (15%) pts experiencing partial response (PR) and 8 (40%) with stable disease. No complete responses were observed, 8 (40%) pts had progressive disease and 1 subject was considered not evaluable. All PRs were achieved in Group B and had duration of 2-4 months (mo). Median PFS was 3.73 mo (95% confidence interval [CI] 3.06-6.79) in the overall population, and showed a trend favoring the combination arm (2.80 mo for Group A vs. 5.03 mo for Group B, hazard ratio 0.71 [CI 0.26-1.95], p = 0.503). Most common toxicities were skin-related side effects (n = 10; 50%), myalgia/arthralgia (n = 5; 25%), nausea (n = 3; 15%), and pyrexia (n = 3; 15%). Grade 3/4 toxicities were uncommon and manageable: neutropenia (n = 1; 5%), hypophosphatemia (n = 1; 5%), pyrexia (n = 1; 5%), and abdominal pain (n = 1; 5%). Conclusions: Our cohort of pts treated with BRAF +/- MEK inhibitors showed a favorable safety profile. An encouraging activity level was found in the combination arm. In line with existing literature data, our findings supporting further development of combined MAPK inhibition in V600-positive mCRC.

Safety and Efficacy of Durvalumab (MEDI4736), an Anti-Programmed Cell Death Ligand-1 Immune Checkpoint Inhibitor, in Patients With Advanced Urothelial Bladder Cancer

PURPOSE

To investigate the safety and efficacy of durvalumab, a human monoclonal antibody that binds programmed cell death ligand-1 (PD-L1), and the role of PD-L1 expression on clinical response in patients with advanced urothelial bladder cancer (UBC).

METHODS

A phase 1/2 multicenter, open-label study is being conducted in patients with inoperable or metastatic solid tumors. We report here the results from the UBC expansion cohort. Durvalumab (MEDI4736, 10 mg/kg every 2 weeks) was administered intravenously for up to 12 months. The primary end point was safety, and objective response rate (ORR, confirmed) was a key secondary end point. An exploratory analysis of pretreatment tumor biopsies led to defining PD-L1-positive as ≥ 25% of tumor cells or tumor-infiltrating immune cells expressing membrane PD-L1.

RESULTS

A total of 61 patients (40 PD-L1-positive, 21 PD-L1-negative), 93.4% of whom received one or more prior therapies for advanced disease, were treated (median duration of follow-up, 4.3 months). The most common treatment-related adverse events (AEs) of any grade were fatigue (13.1%), diarrhea (9.8%), and decreased appetite (8.2%). Grade 3 treatment-related AEs occurred in three patients (4.9%); there were no treatment-related grade 4 or 5 AEs. One treatment-related AE (acute kidney injury) resulted in treatment discontinuation. The ORR was 31.0% (95% CI, 17.6 to 47.1) in 42 response-evaluable patients, 46.4% (95% CI, 27.5 to 66.1) in the PD-L1-positive subgroup, and 0% (95% CI, 0.0 to 23.2) in the PD-L1-negative subgroup. Responses are ongoing in 12 of 13 responding patients, with median duration of response not yet reached (range, 4.1+ to 49.3+ weeks).

CONCLUSION

Durvalumab demonstrated a manageable safety profile and evidence of meaningful clinical activity in PD-L1-positive patients with UBC, many of whom were heavily pretreated.

Higher Risk of Infections with PI3K-AKT-mTOR Pathway Inhibitors in Patients with Advanced Solid Tumors on Phase I Clinical Trials

PURPOSE

Novel antitumor therapies against the PI3K-AKT-mTOR pathway are increasingly used to treat cancer, either as single agents or in combination with chemotherapy or other targeted therapies. Although these agents are not known to be myelosuppressive, an increased risk of infection has been reported with rapamycin analogues. However, the risk of infection with new inhibitors of this pathway such as PI3K, AKT, mTORC 1/2, or multikinase inhibitors is unknown.

EXPERIMENTAL DESIGN

In this retrospective case-control study, we determined the incidence of infection in a group of 432 patients who were treated on 15 phase I clinical trials involving PI3K-AKT-mTOR pathway inhibitors (cases) versus a group of 100 patients on 10 phase I clinical trials of single agent non-PI3K-AKT-mTOR pathway inhibitors (controls) which did not involve conventional cytotoxic agents. We also collected data from 42 patients who were treated with phase I trials of combinations of PI3K-AKT-mTOR inhibitors and MEK inhibitors and 24 patients with combinations of PI3K-AKT-mTOR inhibitors and cytotoxic chemotherapies.

RESULTS

The incidence of all grade infection was significantly higher with all single-agent PI3K-AKT-mTOR inhibitors compared with the control group [27% vs. 8%, respectively, OR, 4.26; 95% confidence intervals (CI), 1.9-9.1, P = 0.0001]. The incidence of grade 3 and 4 infection was also significantly higher with PI3K-AKT-mTOR inhibitors compared with the control group (10.3% vs. 3%, OR, 3.74; 95% CI, 1.1-12.4; P = 0.02). Also, the combination of PI3K-AKT-mTOR inhibitors and chemotherapy was associated with a significantly higher incidence of all grade (OR, 4.79; 95% CI, 2.0-11.2; P = 0.0001) and high-grade (OR, 2.87; 95% CI, 1.0-7.6; P = 0.03) infection when compared with single-agent PI3K-AKT-mTOR inhibitors.

CONCLUSIONS

Inhibitors of the PI3K-AKT-mTOR pathway can be associated with a higher risk of infection. Combinations of PI3K-AKT-mTOR inhibitors and cytotoxic chemotherapy significantly increase the risk of infection. This should be taken into consideration during the design and conduct of trials involving PI3K-AKT-mTOR pathway inhibitors, particularly when combined with chemotherapy or myelosuppressive agents.

Evaluation of candidate spermatogonial markers ID4 and GPR125 in testes of adult human cadaveric organ donors

The optimal markers for human spermatogonial stem cells (SSCs) are not known. Among the genes recently linked to SSCs in mice and other animals are the basic helix-loop-helix transcription factor ID4 and the orphan G-protein-coupled receptor GPR125. While ID4 and GPR125 are considered putative markers for SSCs, they have not been evaluated for coexpression in human tissue. Furthermore, neither the size nor the character of the human spermatogonial populations that express ID4 and GPR125, respectively, are known. A major barrier to addressing these questions is the availability of healthy adult testis tissue from donors with no known reproductive health problems. To overcome this obstacle, we have employed healthy testicular tissue from a novel set of organ donors (n = 16; aged 17-68 years) who were undergoing post-mortem clinical organ procurement. Using immunolabelling, we found that ID4 and GPR125 are expressed on partially overlapping spermatogonial populations and are more broadly expressed in the normal adult human testis. In addition, we found that expression of ID4 remained stable during ageing. These findings suggest that ID4 and GPR125 could be efficacious for identifying previously unrecognized human spermatogonial subpopulations in conjunction with other putative human stem cell markers, both in younger and older donors.

Is uterine serous carcinoma a part of hereditary breast cancer syndrome?

5587

Background: Whilst the association between breast cancer and uterine serous carcinoma (USC) is attributed to tamoxifen treatment, few studies have reported that this increased risk is independent of tamoxifen. Methods: To further investigate the relationship between breast cancer and USC, we retrospectively studied 216 patients from 5 hospital trusts in Birmingham, UK who were diagnosed with USC between 1993 and 2012. We collected personal history of cancer in these cases before or after USC diagnosis. In addition FIGO staging, clinical and survival data were collected from our local cancer registry and patients’ clinical records. Results: In this case series, 56 patients (25.9%) had personal history of at least one cancer before and 18 patients (8.3%) had history of at least one cancer after the diagnosis of USC. Within the group of patients with the history of cancer before the USC, 38 patients (68%, 17.5% of all cases) had personal history of breast cancer prior to the development of USC, higher than the UK expected age standardised relative incidence of breast cancer (350 in 100,000, CRUK 2006-2008). Although 27/38 cases (71%) had endocrine treatment for their primary breast cancer, 11/38 patients (29%) did not have any tamoxifen treatment due to hormone receptor negative breast cancer. Additionally the median age of breast cancer diagnosis for the hormone receptor negative group was significantly lower than those patients who had hormonal treatment for their breast cancer (56 vs. 64 years, p :0.036) compatible with the younger age at diagnosis expected of the familial (BRCA mutated) or triple negative breast cancer. Of 18 patients with a second cancer after diagnosis of USC, 6 patients (33%) were diagnosed with breast/ovarian cancer. This group also had no treatment with tamoxifen. Conclusions: Lack of exposure to tamoxifen and younger age at diagnosis in this subgroup suggest that other factors such as a common underlying genetic predisposition may be responsible for the development of both malignancies. We propose that at least a subgroup of USC may be a part of hereditary breast cancer syndrome. This may have implications in prevention (prophylactic hysterectomy) or trials of targeted treatments (PARP inhibitors) for a subgroup of USC patients.

Tetrathiomolybdate-associated copper depletion decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse

BACKGROUND

Bone marrow-derived endothelial progenitor cells (EPCs) are critical for metastatic progression. This study explores the effect of tetrathiomolybdate (TM), an anti-angiogenic copper chelator, on EPCs in patients at high risk for breast cancer recurrence.

PATIENTS AND METHODS

This phase 2 study enrolled breast cancer patients with stage 3 and stage 4 without evidence of disease (NED), and stage 2 if triple-negative. TM 100 mg orally was administered to maintain ceruloplasmin <17 mg/dl for 2 years or until relapse. The primary end point was change in EPCs.

RESULTS

Forty patients (28 stage 2/3, 12 stage 4 NED) were enrolled. Seventy-five percent patients achieved the copper depletion target by 1 month. Ninety-one percent of triple-negative patients copper-depleted compared with 41% luminal subtypes. In copper-depleted patients only, there was a significant reduction in EPCs/ml by 27 (P = 0.04). Six patients relapsed while on study, of which only one patient had EPCs maintained below baseline. The 10-month relapse-free survival was 85.0% (95% CI 74.6%-96.8%). Only grade 3/4 toxicity was hematologic: neutropenia (3.1% of cycles), febrile neutropenia (0.2%), and anemia (0.2%).

CONCLUSIONS

TM is safe and appears to maintain EPCs below baseline in copper-depleted patients. TM may promote tumor dormancy and ultimately prevent relapse.

Neo-escape: Neoadjuvant extended sequential chemotherapy with adjuvant postoperative treatment for epithelial nonmucinous advanced inoperable peritoneal malignancy

5046

Background: Neo-Escape was designed to exploit fully the modest non-cross resistance of carboplatin (CBDCA) and paclitaxel (ptx) in an extended sequential regimen, with dose-dense ptx, and address feasibility of combining gemcitabine (gem) with either CBDCA or ptx. Methods: A randomised phase II trial in patients (pts) with untreated (FIGO stage 3C/4) inoperable ovarian, fallopian, or primary peritoneal carcinoma to assess feasibility of two regimens of sequential neoadjuvant-then-adjuvant chemotherapy (CT); (a) CBDCA AUC 2.5 and gem 1000mg/m2 repeated days 1 and 8 q 3 wks x 6 cycles, then ptx 175mg/m2 q 2 wks x 6 cycles (CG-P) or (b) CBDCA AUC 6 q 3 wks x 6 cycles, then ptx 175mg/m2 and gem 2000mg/m2 q 2 wks x 6 cycles (C-PG). All pts were considered for delayed 1o debulking surgery after neoadjuvant CT. The 1o feasibility outcome was % pts completing 12 cycles of CT. Using Fleming’s single stage procedure 44 patients on each arm were needed to test null hypothesis of feasibility ≤60% with 5% 1-sided significance level and 90% power. 2o outcomes included safety, PFS and ORR. Pts were stratified by serum albumin, stage and tumor differentiation. Results: 75 pts were recruited Sept 2007 - May 2011 (28 CG-P; 47 C-PG), median age 62 yr (range 21-75). Recruitment to CG-P closed early due to futility. 52% had albumin >35g/L, 68% FIGO stage 3C and 80% poorly differentiated tumors. 64% on CG-P and 55% on C-PG had debulking surgery as planned and a further 4% on CG-P and 13% on C-GP after completion of all CT. For CG-P 35% achieved 0cm, 35% <1cm and 30% ≥ 1cm residuum; for C-GP 34% 0cm, 13% <1cm and 34% ≥1cm, 19% TBC. 14/28 pts on CG-P completed all 12 cycles (feasibility 50%; 95% CI 31-67%); 37/47 pts on C-PG (feasibility 79% (95% CI 64-88). Main reason for early discontinuation was toxicity on CG-P and disease progression on C-PG. Similar proportions of pts on each arm had dose reductions (68%) or delays (86% on CG-P; 89% on C-PG), mainly for toxicity. 82% of pts experienced grade 3/4 toxicity on CG-P; 72% on C-PG. Median PFS for CG-P is 14.3 mths (95% CI 11.6-15.7mths) and 13.0 mths (95% CI 11.5-15.4mths) for C-PG. Conclusions: CG-P was not feasible at these doses using pre-specified criteria, but C-PG is feasible.

A retrospective study of inflammatory breast cancer patients from seven hospitals in the United Kingdom

e11062

Background: Inflammatory breast cancer (IBC) is an aggressive form of locally advanced breast cancer characterised by rapidly progressive breast erythema, pain and tenderness, oedema and paeu d’orange. It is estimated that between 1-4 % of all newly diagnosed breast cancer patients in the United Kingdom have IBC. Methods: We retrospectively identified 51 patients who were treated for IBC at 7 hospitals in the West midlands area of the United Kingdom between 1997 and 2011. Data including patients’ demographics, clinical, radiological and histopathological characteristics were collected from electronic clinical records. The test for HER-2 over-expression was not carried out routinely before 2002, therefore HER-2 status of such patients were assessed retrospectively on the archived tissues. A cox regression analysis was used for statistical assessment of survival and prognostic factors. Results: Median age at diagnosis was 55 years (range 34-83 yrs). Median overall (OS) and progression free survival (PFS) were 32 months (range 7-97 months) and 27 months (range 2-53 months) respectively. The 3–year survival rate for the entire cohort was 32%. Majority of patients were ER and HER-2 positive (49% and 52% respectively). The rate of complete pathological response (pCR) after neoadjuvant chemotherapy was 14%. All cases who had achieved pCR were HER-2 positive who had received anti HER-2 treatment during the neoadjuvant chemotherapy. The OS for the HER-2 positive patients with pCR was not statistically different from the whole cohort (49 vs 32 months, p=0.09) or from the patients with residual disease (49 vs 26 months, p=0.13). Although the triple negative IBC patients consisted 20% of the cohort, no patients in this group had achieved pCR. The OS and PFS for the triple negative patients were 20 and 14 months respectively. Although the rate of pCR was higher in patients treated with taxane compared to those treated with anthracycline containing chemotherapy (35% vs 7%), there was no significant difference in OS between either of these regimens (29 vs 27 months). Conclusions: HER-2 positive IBC patients had higher rate of achieving pCR after neo-adjuvant anti HER-2 therapy. However higher rate of pCR did not improve the OS.

Evaluation of the derivation of human colon adenocarcinoma from Lgr5 colon stem cells

410

Background: Human colon stem cells share phenotypic hallmarks of self-renewal and proliferation that are associated with tumor cells. Lgr5 is a marker of colon stem cells and not colon differentiated cells. In mice, deletion of the adenomatous polyposis coli gene in colon stem cells but not in colon differentiated cells, rapidly gives rise to macroscopic adenomas. We investigated the role of Lgr5 colon stem cells in human colon tumors in relation to tumor cell of origin, tumor progression, tumor recurrence, and overall survival.

Methods: Using in situ hybridization, we determined the histological distribution of Lgr5 mRNA in human colon specimens at different stages of tumor development and tumor recurrence after chemotherapy. Using gene expression analysis, we analysed Lgr5 mRNA expression levels in human normal colon (n = 33), normal liver (n = 13), colon adenomas (n = 45), primary colon adenocarcinomas (n = 170), liver metastates (n = 48) and lung metastates (n = 20). We examined the correlation between Lgr5 mRNA expression, K-ras mutation status and overall survival in stage IV colon adenocarcinomas.

Results: Human normal colon Lgr5 mRNA was always expressed at basal level and restricted to human colon stem cells. In contrast, we observed an all (Lgr5(+)) or none (Lgr5(-)) expression in human colon adenomas, adenocarcinomas and liver metastases. When present Lgr5 mRNA expression was increased 3-10 fold compared to normal colon. The Lgr5 gene expression analysis provided similar results with increased expression in 66% of human colon adenomas, 62% of primary colon adenocarcinomas, 72% of colon liver metastases and 55% colon lung metastases when compared to normal colon. We have determined that 22.5% (18/80) of Lgr5(+)and 46.4% (26/56) of Lgr5(-) colon adenocarcinoma specimens have K-ras mutations. Kaplan-Meier estimates of median overall survival in Lgr5(+) and Lgr5(-) Stage IV colon adenocarcinomas were 20 months and 15 months, respectively.

Conclusions: Human colon adenocarcinomas are derived predominantly from Lgr5 colon stem cells. Lgr5(+) colon adenocarcinomas required less frequent K-ras mutation for tumor progression then Lgr5(-) colon adenocarcinomas.

No significant financial relationships to disclose.

Abstract P2-16-14: The Effect of Tetrathiomolybdate (TM) on Circulating Endothelial Progenitor Cells in Women at Moderate to High Risk of BC Recurrence

Background: Bone marrow (BM) derived endothelial progenitor cells (EPCs) are critical to tumor angiogenesis, are increased in BC patients (pts) and are probably an early marker for paclitaxel response. Copper is required for angiogenesis, and pre-clinical data suggest that TM, a copperdepleting compound, inhibits angiogenesis and maintains tumor dormancy through unknown mechanisms. We sought to measure the effect of TM on BM derived EPCs in pts at high risk of BC recurrence and to evaluate the effect of copper depletion on their absolute number. Methods: This analysis is part of an ongoing phase II study of TM in BC pts at high risk of recurrence defined as any node positive triple negative (TN) BC, Stage III or IV with no evidence of disease (NED). All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of EPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. Imaging studies are done every 6 months (mos). Initial study duration is 24 mos. Extension study for an additional 24 mos in selected pts. Results: 40 pts are enrolled and 566 cycles of TM have been administered. Adjuvant: 28 pts, Stage 4 NED: 12 pts, Triple negative: 11 pts (4 stage 4 NED, 7 Adjuvant). Median age is 51 yrs (range: 29-64). Median number of positive lymph nodes among Stage 2/3 pts is 7 (4-42). Median baseline Cp level is 29 mg/dL (21-47). Among 36 pts who have reached target Cp, the median time to target is 4 wks (2-20 wks). Four pts discontinued treatment before reaching target. The median baseline EPCs is 0.01 cells/ml (0.0-0.286), and the majority of pts’ EPCs were maintained below baseline when Cp levels remained below target (i.e. copper depleted). Toxicity: Grade 3/4 neutropenia occurred in 15 cycles (2.6%) with 1 pt with febrile neutropenia. One cycle was complicated by Grade 3 anemia. All resolved 5-13 days later with TM held and resumed at a lower dose. No other grade 3/4 toxicity was observed. Six pts were diagnosed with recurrent breast cancer at 1, 2, 2, 9, 10 and 10 mos. An EPC rise preceded an abnormal marker or overt relapse by 3-5 months in 4 of 6 pts (2 pts too early to tell). Conclusions: TM is well tolerated in breast cancer patients. TM might contribute to maintaining EPCs below baseline in pts who are copper depleted. We postulate that the increased EPCs noted in 4 pts with recurrent disease 2-4 months prior to overt relapse could represent the turning on of an angiogenic switch, resulting in an outpouring of BM derived EPCs to the new site of metastasis. Other studies geared toward understanding the mechanism for metastases are underway. The trial continues to accrue.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-16-14.

The role of maintenance pemetrexed in the treatment of non-small-cell lung cancer

Until recently, the weight of evidence has supported the discontinuation of chemotherapy in advanced non-small-cell lung cancer (NSCLC) after 4-6 cycles of induction therapy. This allows patients with limited life expectancy a "treatment holiday." A minority of cases then go on to receive second-line therapy, although many deteriorate rapidly and never receive further active treatment. There has been renewed interest in the concept of maintenance from trials with pemetrexed and erlotinib. Both these agents can be given for long periods without serious cumulative toxicity in most patients. Both trials have shown significant extension of progression free survival in placebo-controlled trials. In cases who are not receiving pemetrexed as induction therapy, a statistically significant 5-month prolongation of overall survival in nonsquamous NSCLC has been reported. Treatment was well tolerated. This effect may reflect the early administration of an active second-line agent and it remains to be seen whether similar benefits will accrue to patients having pemetrexed as induction therapy.

A Phase II Trial Tetrathiomolybdate (TM), a Copper Depleting Compound, and Its Effect on Circulating Endothelial Progenitor Cells (EPCs) in Patients with Breast Cancer (BC) at High Risk of Recurrence

Background: EPCs are critical to tumor angiogenesis, are increased in BC patients (pts) and are probably an early marker for paclitaxel response. Copper is required for angiogenesis, and pre-clinical data suggest that TM, a copper-depleting compound, inhibits angiogenesis and maintains tumor dormancy. We sought to measure the effect of TM on circulating endothelial progenitor cells (EPCs) in pts at high risk of BC recurrence and to evaluate the effect of copper depletion on EPCs. Methods: This analysis is part of an ongoing phase II study of TM in BC pts at high risk of recurrence defined as any node positive triple negative (TN) BC, Stage III or IV with no evidence of disease (NED). All therapy other than hormonal was completed at least 6 weeks prior to study. Treatment: TM 180 mg daily to achieve a target ceruloplasmin (Cp) level of 5-15 mg/dL (copper depletion), and then 100 mg daily. We monitored levels of EPCs (CD45dim, CD133+, VEGFR2+), CEA, CA15-3, and Cp at baseline and monthly. Imaging studies are done every 6 months (mos). Results: 28 pts are enrolled and 304 cycles of TM have been administered. Adjuvant: 20 pts, Stage 4 NED: 8 pts, Triple negative: 8 pts (5 stage IV NED, 3 Adjuvant) The median age is 51 years (range: 29-64), median number of positive lymph nodes among Stage III patients is 7 (4-42). The median baseline Cp level was 28 mg/dL (21-43). Among 21 patients who have reached target Cp, the median time to target is 6 weeks (2-16 weeks). Two pts discontinued treatment before reaching target. The median baseline EPCs is 17.38 cells/ml (0.0-286.1) Although there was a trend toward increased EPCs at month 1, this was not statistically significant (p=0.8964) and the majority of pts EPCs were maintained below baseline over time when Cp levels were below target (ie. copper depleted). Toxicity: Grade 3/4 neutropenia occurred in 3 patients (0.02%) with 1 pt with febrile neutropenia. All resolved 5-13 days later with TM held and resumed at a lower dose in 2 patients. No other grade 3/4 toxicity was observed. Three patients were diagnosed with recurrent breast cancer at 1, 9 and 10 mos. An EPC rise preceded an abnormal marker or overt relapse by 3-5 months in 2 of 3 pts. Conclusions: TM is well tolerated in breast cancer patients. TM might contribute to maintaining EPCs below baseline in pts who are copper depleted. We postulate that the increased EPCs noted in both patients with recurrent disease 2-4 months prior to overt relapse could represent the turning on of an angiogenic switch, resulting in an outpouring of CEPCs to the new site of metastasis. Other studies geared toward understanding the mechanism for metastases are underway. The trial continues to accrue.Supported by the Susan B Komen for the Cure, NY Community Trust, Breast Cancer Alliance of Greenwich and the Madeline and Stephen Anbinder Foundation.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6090.

Five polymorphisms and breast cancer risk: results from the Breast Cancer Association Consortium

Previous studies have suggested that minor alleles for ERCC4 rs744154, TNF rs361525, CASP10 rs13010627, PGR rs1042838, and BID rs8190315 may influence breast cancer risk, but the evidence is inconclusive due to their small sample size. These polymorphisms were genotyped in more than 30,000 breast cancer cases and 30,000 controls, primarily of European descent, from 30 studies in the Breast Cancer Association Consortium. We calculated odds ratios (OR) and 95% confidence intervals (95% CI) as a measure of association. We found that the minor alleles for these polymorphisms were not related to invasive breast cancer risk overall in women of European descent: ECCR4 per-allele OR (95% CI) = 0.99 (0.97-1.02), minor allele frequency = 27.5%; TNF 1.00 (0.95-1.06), 5.0%; CASP10 1.02 (0.98-1.07), 6.5%; PGR 1.02 (0.99-1.06), 15.3%; and BID 0.98 (0.86-1.12), 1.7%. However, we observed significant between-study heterogeneity for associations with risk for single-nucleotide polymorphisms (SNP) in CASP10, PGR, and BID. Estimates were imprecise for women of Asian and African descent due to small numbers and lower minor allele frequencies (with the exception of BID SNP). The ORs for each copy of the minor allele were not significantly different by estrogen or progesterone receptor status, nor were any significant interactions found between the polymorphisms and age or family history of breast cancer. In conclusion, our data provide persuasive evidence against an overall association between invasive breast cancer risk and ERCC4 rs744154, TNF rs361525, CASP10 rs13010627, PGR rs1042838, and BID rs8190315 genotypes among women of European descent.

Angiogenesis and antiangiogenic therapy in non-Hodgkin's lymphoma

Angiogenesis, the growth of new blood vessels, requires dynamic expansion, assembly and stabilization of vascular endothelial cells in response to proangiogenic stimuli. Antiangiogenic strategies have become an important therapeutic modality for solid tumors. While many aspects of postnatal pathological angiogenesis have been extensively studied in the context of nonhematopoietic neoplasms, the precise role of these processes in lymphoma pathogenesis is under active investigation. Lymphoma growth and progression is potentiated by at least two distinct angiogenic mechanisms: autocrine stimulation of tumor cells via expression of vascular endothelial growth factor (VEGF) and VEGF receptors by lymphoma cells, as well as paracrine influences of proangiogenic tumor microenvironment on both local neovascular transformation and recruitment of circulating bone marrow-derived progenitors. Lymphoma-associated infiltrating host cells including hematopoietic monocytes, T cells and mesenchymal pericytes have increasingly been associated with the pathogenesis and prognosis of lymphoma, in part providing perivascular guidance and support to neoangiogenesis. Collectively, these distinct angiogenic mechanisms appear to be important therapeutic targets in selected non-Hodgkin's lymphoma (NHL) subtypes. Understanding these pathways has led to the introduction of antiangiogenic treatment strategies into the clinic where they are currently under assessment in several ongoing studies of NHL patients.

Hemangiogenic response after pre-operative COX2 inhibition predicts recurrence in esophageal cancer

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Background: Growth of esophageal cancer involves a proliferative hemangiogenic component. Biomarkers that predict this propensity in esophageal cancer and the impact of anti-angiogenic strategy on their levels as well as clinical response remain unknown. Methods: A multimodular approach was devised to assess hemangiogenic parameters in a cohort of chemotherapy naïve patients with locally advanced (T2-T3N0, T1-T3N1M0M1a) esophageal cancer pre- and 4 days post-celecoxib neoadjuvant treatment. Patients went on to receive neoadjuvant therapy with celecoxib, paclitaxel and carboplatin for 3 cycles, followed by surgical resection. This bioassay panel consists of 5 components: i) HUVEC-based angiogenic scale for functional plasma angiogenic activity, ii) flow cytometry to quantify CD133+VEGFR2+ circulating endothelial progenitors (CEPs), iii) hematopoietic colony-forming assay to quantify circulating hematopoietic progenitors (CHPs), iv) plasma SDF-1 level, and v) platelet VEGF-A level. Results: The cohort consists of 8 consecutive patients (6 men, 2 women) with median age of 58. After 18 months of followup, 6 patients remained alive and without evidence of recurrence, while 2 had tumor recurrence and metastasis. Analysis of the positive responders (pre-celecoxib baseline versus 4 days post treatment) revealed a global suppression of hemangiogenic parameters with reduction of the functional HUVEC-based angiogenic scale (mean score of 3.3 versus 1.8; p<0.05), 2.2-fold decrease in CEPs (p<0.05), and 3-fold decrease in CHPs (p<0.05). This trend also correlated with decreased plasma SDF-1 and platelet VEGF-A levels . However, in the 2 cases of tumor recurrence, the initial hemangiogenic response was blunted with no significant difference in all parameters tested during the celecoxib monotherapy period. Conclusion: Esophageal cancer development involved a hemangiogenic switch toward increased CEPs, CHPs, and functional plasma pro-angiogenic activity. COX2 inhibition with celecoxib normalized the hemangiogenic profile. Collective assessment of hemangiogenic biomarkers during neoadjuvant setting may be a promising tool in predicting clinical outcomes, recurrence, and for validating impact of anti-angiogenic therapy on esophageal cancer.

No significant financial relationships to disclose.

Beta-galactosidase staining on bone marrow. The osteoclast pitfall

The enzyme beta-galactosidase, encoded by the bacterial gene lac-Z, is commonly used as a histochemical reporter to track transplanted cells in vivo or to analyze temporospatial gene expression patterns by coupling expression of specific target genes to beta-galactosidase activity. Previously, endogenous beta-galactosidase activity has been recognized as a confounding factor in the study of different soft tissues, but there is no description of the typical background on bone marrow sections when using the chromogenic substrate 5-Bromo-4-chloro-3-indolyl beta-D-Galactoside (X-Gal). In this report, we show that osteoclasts in bone marrow sections specifically and robustly stain blue with X-Gal. This leads to a typical background when bone marrow is examined that is present from the first day post partum throughout the adult life of experimental mice and can be confused with transgenic, bacterial beta-galactosidase expressing hematopoietic or stromal cells. Experimental variations in the X-Gal staining procedure, such as pH and time of exposure to substrate, were not sufficient to avoid this background. Therefore, these data demonstrate the need for strenuous controls when evaluating beta-galactosidase positive bone marrow cells. Verifiable bacterial beta-galactosidase positive bone marrow cells should be further identified using immunohistological or other approaches. Specifically, beta-galactosidase positive hematopoietic or stromal cells should be proven specifically not to be osteoclasts by co-staining or staining adjacent sections for specific markers of hematopoietic and stromal cells.

Thrombopoietic cells and the bone marrow vascular niche

Megakaryocytes and platelets have been known to secrete angiogenic growth factors for a long time. However, there is little in vivo data on the regulation of angiogenesis by thrombopoietic cells. Both megakaryocytes and platelets are known to carry and release a multitude of both pro- and antiangiogenic mediators. Thus, it remained unknown how the "angiogenic phenotype" of thrombopoietic cells would be determined. Our group established that platelets contribute to angiogenesis as carriers of SDF-1, which is released by platelets in response to stimulation with hematopoietic cytokines. Indeed, even the action of VEGF-A seems to be mediated in part by the release of SDF-1 from stimulated platelets, thereby attracting proangiogenic hematopoietic cells. Moreover, the analysis of murine plasma and serum showed that similar to VEGF-A, SDF-1 is almost exclusively derived from platelets, and only trace amounts are detectable in platelet poor plasma. Because tumor patients' platelets have been shown to contain lower amounts of thrombospondin (Tsp), we generated Tsp-1 and Tsp-2 double knockout mice by crossing the single knockout lines. Interestingly, megakaryocytes and platelets derived from these mice confer a proangiogenic phenotype both in the bone marrow and in reperfusion of ischemic hindlimbs, thereby verifying the hypothesis of pro- and antiangiogenic platelet constituents "in balance."

Activation of FGFR1beta signaling pathway promotes survival, migration and resistance to chemotherapy in acute myeloid leukemia cells

Fibroblast growth factors (FGFs) are important regulators of hematopoiesis and have been implicated in the tumorigenesis of solid tumors. Recent evidence suggests that FGF signaling through FGF receptors (FGFRs) may play a role in the proliferation of subsets of acute myeloid leukemias (AMLs). However, the precise mechanism and specific FGF receptors that support leukemic cell growth are not known. We show that FGF-2, through activation of FGFR1beta signaling, promotes survival, proliferation and migration of AML cells. Stimulation of FGFR1beta results in phosphoinositide 3-kinase (PI3-K)/Akt activation and inhibits chemotherapy-induced apoptosis of leukemic cells. Neutralizing FGFR1-specific antibody abrogates the physiologic and chemoprotective effects of FGF-2/FGFR1beta signaling and inhibits tumor growth in mice xenotransplanted with human AML. These data suggest that activation of FGF-2/FGFR1beta supports progression and chemoresistance in subsets of AML. Therefore, FGFR1 targeting may be of therapeutic benefit in subsets of AML.

Circulating endothelial progenitor cells correlate to stage in patients with invasive breast cancer

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Background: Tumor growth and metastasis is dependent on neo-angiogenesis. Both pre-existing and circulating vascular cells have been shown to contribute to the assembly of tumor neo-vessels in specific tumors. Mobilization of endothelial progenitor cells (EPCs) from the bone marrow constitutes a crucial step in the formation of de novo blood vessels, and levels of peripheral blood EPCs have been shown to be increased in certain malignant states. However, the role of circulating EPCs in breast cancer is largely unknown. Methods: We recruited twenty-five patients with biopsy-proven invasive breast cancer (BC) at Weill Cornell Breast Center to participate in a pilot study investigating the correlation of circulating EPCs to extent of disease and initiation of chemotherapy. For each patient, a baseline sample was drawn before systemic treatment, and for seventeen of those patients, a second sample was taken after the first round of chemotherapy. Levels of peripheral blood EPCs, as defined by co-expression of CD133 and VEGFR2, were quantified by flow cytometry. Results: BC patients with stage III & IV disease had statistically higher levels of circulating EPCs than did patients with stage I & II disease (median=165,000 EPCs/5×106MNCs vs. median=6,920 EPCs/5x106MNCs, respectively, p < 0.0001 by Wilcoxon rank-sum test). In addition, in late-stage patients, levels of EPCs demonstrated a statistically significant drop after initiation of chemotherapy (median=162,500 EPCs/5x106MNCs [pre] vs. median=117,500 EPCs/5x106MNCs [post], p = 0.01 by Wilcoxon signed-rank test). Conclusion: These results suggest that circulating EPCs may serve as a potential tumor biomarker in breast cancer and that EPCs may represent a plausible target for future therapeutic intervention. Supported in part by the Mentored Medical Student in Clinical Research Program (General Clinical Research Center/National Institutes of Health Grant M01RR00047), Madeline & Stephen Anbinder Clinical Scholar Award, and Anne Moore Breast Cancer Research Fund

No significant financial relationships to disclose.

Mitotic defects in XRCC3 variants T241M and D213N and their relation to cancer susceptibility

The XRCC3 variant T241M, but not D213N, has been reported to be associated with an increased risk of some cancers. XRCC3 is one out of five RAD51 paralogues and is involved in homologous recombination, as are the BRCA1 and BRCA2 proteins. However, in contrast to mutations in BRCA1 and BRCA2, the XRCC3(T241M) protein is proficient in homologous recombination and reverts sensitivity to mitomycin C found in XRCC3-deficient cells, whereas XRCC3(D213N) is defective in homologous recombination. Here, we report that both the XRCC3 D213N and T241M alleles are associated with an increase in centrosome number and binucleated cells. However, only the D213N allele gives an increase in spontaneous levels of apoptosis. We suggest that the inability of XRCC3 T241M to apoptotically eliminate aberrant cells with mitotic defects could increase cancer susceptibility in individuals carrying this variant. In contrast, cells carrying the XRCC3 D213N variant are able to eliminate aberrant cells by apoptosis, and consistent with this observation, this variant does not seem to be associated with cancer susceptibility.