Placental metastasis from maternal NUT carcinoma: diagnostic pitfalls and challenges

We report a young pregnant woman with large midline thoracic mass and markedly elevated serum alpha-fetoprotein (AFP) levels. Initially suspected as a germ cell tumour (GCT) due to age, site, and high AFP levels, a biopsy unveiled a high-grade malignant tumour characterised by undifferentiated monotonous cells. Although tumour cells exhibited positive AFP, the overall immunoprofile did not provide additional evidence to support GCT. Further work-up showed positive for NUT (nuclear protein in testis) immunostaining and the presence of BRD4-NUT1 fusion, confirming the diagnosis of NUT carcinoma. On radiology, there were extensive metastases to lungs, liver, vertebrae, and placenta. Despite aggressive chemotherapy, radiotherapy and immunotherapy, she did not respond to the therapies. Fortunately, her child was not affected by the carcinoma. This is the first case highlighting that thoracic lung primary NUT carcinoma can spread to the placenta and manifest with elevated serum AFP levels, potentially leading to misdiagnosis as GCT both clinically and pathologically.

Intrathecal trastuzumab versus alternate routes of delivery for HER2-targeted therapies in patients with HER2+ breast cancer leptomeningeal metastases

BACKGROUND

Patients with HER2+ breast cancer (BC) frequently develop leptomeningeal metastases (LM). While HER2-targeted therapies have demonstrated efficacy in the neoadjuvant, adjuvant, and metastatic settings, including for parenchymal brain metastases, their efficacy for patients with LM has not been studied in a randomized controlled trial. However, several single-armed prospective studies, case series and case reports have studied oral, intravenous, or intrathecally administered HER2-targeted therapy regimens for patients with HER2+ BC LM.

METHODS

We conducted a systematic review and meta-analysis of individual patient data to evaluate the efficacy of HER2-targeted therapies in HER2+ BC LM in accordance with PRISMA guidelines. Targeted therapies evaluated were trastuzumab (intrathecal or intravenous), pertuzumab, lapatinib, neratinib, tucatinib, trastuzumab-emtansine and trastuzumab-deruxtecan. The primary endpoint was overall survival (OS), with CNS-specific progression-free survival (PFS) as a secondary endpoint.

RESULTS

7780 abstracts were screened, identifying 45 publications with 208 patients, corresponding to 275 lines of HER2-targeted therapy for BC LM which met inclusion criteria. In univariable and multivariable analyses, we observed no significant difference in OS and CNS-specific PFS between intrathecal trastuzumab compared to oral or intravenous administration of HER2-targeted therapy. Anti-HER2 monoclonal antibody-based regimens did not demonstrate superiority over HER2 tyrosine kinase inhibitors. In a cohort of 15 patients, treatment with trastuzumab-deruxtecan was associated with prolonged OS compared to other HER2-targeted therapies and compared to trastuzumab-emtansine.

CONCLUSIONS

The results of this meta-analysis, comprising the limited data available, suggest that intrathecal administration of HER2-targeted therapy for patients with HER2+ BC LM confers no additional benefit over oral and/or IV treatment regimens. Although the number of patients receiving trastuzumab deruxtecan in this cohort is small, this novel agent offers promise for this patient population and requires further investigation in prospective studies.

PARP Inhibition Sensitizes Breast Cancer Cells to Eribulin

BACKGROUND

Poly(ADP-ribose) polymerases 1 and 2 (PARP1, 2), and 3 mediate protein modifications that facilitate the recruitment of DNA repair factors to single and double strand breaks. PARP3 is unique in that it is also required for efficient mitotic progression and stabilization of the mitotic spindle. Eribulin, an anti-microtubule agent used clinically to treat breast cancer, exerts its cytotoxicity by altering microtubule dynamics resulting in cell cycle arrest and apoptosis. Herein, we hypothesize that the pan PARP inhibitor olaparib has the potential to enhance the cytotoxicity of eribulin by halting mitosis through inhibition of PARP3.

METHODS

The effect of olaparib on eribulin cytotoxicity was assessed using the Sulforhodamine (SRB) assay, with two triple negative breast cancer cell lines and an estrogen receptor positive (ER+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer cell line. Alteration by the treatments on PARP3 activity and microtubule dynamics were assessed utilizing a chemiluminescent enzymatic assay and immunofluorescence, respectively. The effect of the treatments on cell cycle progression and apoptosis induction were assessed by flow cytometry using propidium iodide and Annexin V staining, respectively.

RESULTS

Our results demonstrate that non-cytotoxic concentrations of olaparib sensitize breast cancer cells regardless of ER status. Mechanistically, our results indicate that olaparib potentiates eribulin-induced cell cycle arrest at the G2/M boundary, PARP3 inhibition and microtubule destabilizing resulting in mitotic catastrophe and apoptosis.

CONCLUSIONS

In breast cancer (regardless of ER status) settings, treatment outcomes could be improved by the incorporation of olaparib in eribulin treatment regimens.

Abstract P2-01-06: Real-world outcome and cost analysis of the addition of pertuzumab to neoadjuvant therapy in localized HER2 positive breast cancer: a single center experience

BACKGROUND: Breast cancer is the most common cancer in woman and can be classified based on the expression of hormonal receptor as well as the human epidermal growth factor receptor 2 (HER2). HER2 amplification is associated with an aggressive clinical course and higher recurrence rates following curative intend surgery. For non-metastatic T2 or node-positive HER2-positive disease neoadjuvant treatment is favored. The National Comprehensive Cancer Network (NCCN) guidelines have endorsed the use of dual HER2 blockage with trastuzumab and pertuzumab combined with chemotherapy in the neoadjuvant setting. However, pertuzumab isn’t frequently reimbursed in public health care systems for this indication. Patients who don’t achieve a pathological complete response (pCR) at surgery are eligible for adjuvant T-DM1, adding significant side effects on patients and cost on the healthcare system.

METHODS: We conducted a retrospective analysis of patients receiving anti-HER2 therapy in the neoadjuvant setting at the Jewish General hospital between 2015 and 2021. After 2019, pertuzumab was routinely added to standard neoadjuvant therapy enabling us to compare patients treated with or without dual-HER2 blockade. Our primary endpoint is the percentage of pCR at surgery. Secondary objectives are to estimate and compare the cost of anti-HER2 targeted therapy in the perioperative setting and side effect burden on patients. Statistical analyses were done using fisher exact test with statistical significance defined p value < 0.05 in a one-sided test. Drug cost was calculated using publicly available resources.

RESULTS: We identified 83 patient who underwent neoadjuvant chemotherapy for HER2 amplified breast cancer. 44 patients received only trastuzumab has anti-HER2 therapy and 39 patients were treated with dual HER2 blockade containing pertuzumab. The addition of pertuzumab was associated with improved the pCR rate (67% vs. 27%; p = 0.0016). The increased pCR rate was observed in hormone-receptor positive and negative tumors. We also described a non-statistically significant trend in reduction in the requirement for axillary dissection with the use of pertuzumab (28% vs. 39%; P=0.2208). The increased in pCR rate with pertuzumab reduced the number of patients eligible for adjuvant T-DM1. If all patients with residual disease had received adjuvant T-DM1, the cost of neoadjuvant pertuzumab would be neutral, with a mean anti-HER2 drug cost of 65 150 CA$ in the pertuzumab-trastuzumab group and 66 116 CA$ in the trastuzumab group.

CONCLUSION: Our real-world analysis confirmed that neoadjuvant chemotherapy with dual HER2-blockade was well tolerated and associated with increased the pCR rate compared to regimens containing trastuzumab only. This measure is neutral on drug cost by reducing the amount of patients eligible for adjuvant T-DM1. Further research is warranted to estimate the overall health-care utilization costs of neoadjuvant pertuzumab-trastuzumab in settings where adjuvant T-DM1 is available.

Table 3: Pathologic complete response (pCR) and type of surgery in patients who received dual HER2 blockade with neoadjuvant pertuzumab-trastuzumab plus chemotherapy and in patients receiving trastuzumab only with chemotherapy at Jewish General Hospital between 2015 and 2021. ** p < 0,01, ns non-statistically significant

Citation Format: Francois Panet, Matt Young, Stephanie Wong, Alice Dragomir, April A. N. Rose, Lawrence Panasci. Real-world outcome and cost analysis of the addition of pertuzumab to neoadjuvant therapy in localized HER2 positive breast cancer: a single center experience [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-01-06.

The risks associated with the widespread use of telemedicine in oncology: Four cases and review of the literature

BACKGROUND

COVID-19 changed the way we practice oncology in multiple ways. Because most cancer patients are comorbid or immunocompromised, we are trying as much as possible to reduce their risk of infection. Marginal just 2 years ago, telemedicine quickly became preeminent with the pandemic to reduce hospital exposure. However, using only virtual visits in oncology patients risk delaying cancer diagnosis or the identification of a complication.

CASE SERIES

We present here four cases where a serious medical problem evident on physical exam was overlooked during a virtual visit. Two of our patients experienced a delay in cancer diagnosis thus putting them at risk of local or distant spread. The two others were established oncology patients where a serious medical complication was missed on a virtual visit.

CONCLUSIONS

Now more than a year into the pandemic, telemedicine has clearly been a useful tool by limiting unnecessary hospital visits. Yet, as our cases illustrate, its use in oncology without clear boundary can undermine the quality of care. Now that effective vaccines are reducing the transmission and the severity of infection, most oncology patients can be evaluated by a real-time visit.

IND.216: a phase II study of buparlisib and associated biomarkers, raptor and p70S6K, in patients with relapsed and refractory chronic lymphocytic leukemia

Buparlisib is an orally available pan-Class I PI3K inhibitor, that is more potent than idelalisib in vitro. Its distinct toxicities include hyperglycemia, hypertension, and mood disturbance. IND216 is a single arm phase II trial of buparlisib in Relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Fourteen patients were enrolled, 13 were evaluable for response and toxicity. Six of 13 patients had a partial response (46%) with a median duration of response of 15.5 months, all 11 patients with tumor assessment experienced tumor shrinkage. The most common adverse events (≥15%) were hyperglycemia, fatigue, anxiety, and gastrointestinal toxicities; all were < grade 3 except for fatigue. Three patients stopped therapy for alterations in mood. Lower levels of raptor were significantly associated with greater tumor shrinkage, suggesting that raptor could be a biomarker for response. This requires further validation in a larger CLL patient cohort. The clinical activity of buparlisib is comparable to other phosphatidylinositol-3-kinase inhibitors, with a different toxicity profile.Novelty and impactBuparlisib, an oral, pan PI3 kinase inhibitor, is associated with a 46% partial response rate among patients with relapse chronic lymphocytic leukemia (CLL). This is a similar clinical activity to other phosphatidylinositol-3-kinase inhibitors tested. However, buparlisib has a distinct toxicity profile, characterized by hyperglycemia, hypertension, and mood alteration. In agreement with our previous preclinical study, our results suggest that basal raptor expression in CLL correlates with clinical response to buparlisib.

PARP3 inhibitors ME0328 and olaparib potentiate vinorelbine sensitization in breast cancer cell lines

PURPOSE

PARP-3 is member of the PARP family of poly (ADP-ribose) polymerases involved in ADPribosylation. PARPs are involved in the basic mechanisms of DNA repair. PARP3, a critical player for efficient mitotic progression, is required for the stabilization of the mitotic spindle by regulation of the mitotic components, NuMA and Tankyrase 1.

METHODS

The sensitization effect of vinorelbine on PARP3 inhibition-induced cytotoxicity was assessed by the SRB assay. The contribution of programed cell death and cell cycle arrest to the sensitization effect were determined by assessing changes in Annexin V, a marker of apoptosis. Alterations in cell cycle progression were assessed by cell cycle analysis. We used immunofluorescence to assess the effect of vinorelbine and/or PARP3 inhibitors on tubulin and microtubule depolarization. The PARP3 chemiluminescent assay kit was used for PARP3 activity.

RESULTS

PARP3 inhibitors sensitize breast cancer cells to vinorelbine, a vinca alkaloid used in the treatment of metastatic breast cancer. Olaparib which was originally described as a PARP1 and 2 inhibitor has recently been shown to be a potent PARP3 inhibitor while ME0328 is a more selective PARP3 inhibitor. The combination of vinorelbine with nontoxic concentrations of ME0328 or olaparib reduces vinorelbine resistance by 10 and 17 fold, respectively, potentiating vinorelbine-induced arrest at the G2/M boundary. In addition, PARP3 inhibition potentiates vinorelbine interaction with tubulin. Furthermore, olaparib or ME0328 potentiates vinorelbine-induced PARP3 inhibition, mitotic arrest, and apoptosis.

CONCLUSION

Our results indicated this approach with PARP3 inhibitors and vinorelbine is unique and promising for breast cancer patients with metastases. This combination could significantly increase the survival of breast cancer patients with metastases.

A randomized phase II study of weekly paclitaxel with or without pelareorep in patients with metastatic breast cancer: final analysis of Canadian Cancer Trials Group IND.213

BACKGROUND

Pelareorep, a serotype 3 reovirus, has demonstrated preclinical and early clinical activity in breast cancer and synergistic cytotoxic activity with microtubule targeting agents. This multicentre, randomized, phase II trial was undertaken to evaluate the efficacy and safety of adding pelareorep to paclitaxel for patients with metastatic breast cancer (mBC).

METHODS

Following a safety run-in of 7 patients, 74 women with previously treated mBC were randomized either to paclitaxel 80 mg/m² intravenously on days 1, 8, and 15 every 4 weeks plus pelareorep 3 × 10¹⁰ TCID₅₀ intravenously on days 1, 2, 8, 9, 15, and 16 every 4 weeks (Arm A) or to paclitaxel alone (Arm B). Primary endpoint was progression-free survival (PFS). Secondary endpoints were objective response rate, overall survival (OS), circulating tumour cell counts, safety, and exploratory correlative analyses. All comparisons used a two-sided test at an alpha level of 20%. Survival analyses were adjusted for prior paclitaxel.

RESULTS

Final analysis was performed after a median follow-up of 29.5 months. Pelareorep was well tolerated. Patients in Arm A had more favourable baseline prognostic variables. Median adjusted PFS (Arm A vs B) was 3.78 mo vs 3.38 mo (HR 1.04, 80% CI 0.76-1.43, P = 0.87). There was no difference in response rate between arms (P = 0.87). Median OS (Arm A vs B) was 17.4 mo vs 10.4 mo (HR 0.65, 80% CI 0.46-0.91, P = 0.1).

CONCLUSIONS

This first, phase II, randomized study of pelareorep and paclitaxel in previously treated mBC did not show a difference in PFS (the primary endpoint) or RR. However, there was a significantly longer OS for the combination. Further exploration of this regimen in mBC may be of interest.

Precision spherical nucleic acids for delivery of anticancer drugs

Highly monodisperse sequence-defined spherical nucleic acids (HE₁₂–SNAs) for delivery of small-molecule anticancer drugs.

We report a spherical nucleic acid (SNA) system for the delivery of BKM120, an anticancer drug for treatment of chronic lymphocytic leukemia (CLL). While promising for cancer treatment, this drug crosses the blood–brain barrier causing significant side-effects in patients. The DNA nanoparticle encapsulates BKM120 in high efficiency, and is unparalleled in its monodispersity, ease of synthesis and stability in different biological media and in serum. These DNA nanostructures demonstrate efficient uptake in human cervical cancer (HeLa) cells, and increased internalization of cargo. In vitro studies show that BKM120-loaded nanoparticles promote apoptosis in primary patient CLL lymphocytes, and act as sensitizers of other antitumor drugs, without causing non-specific inflammation. Evaluation of this drug delivery system in vivo shows long circulation times up to 24 hours, full body distribution, accumulation at tumor sites and minimal leakage through the blood–brain barrier. Our results demonstrate the great potential of these delivery vehicles as a general platform for chemotherapeutic drug delivery.

Abstract CT131: A randomized (RCT) phase II study of oncolytic reovirus (pelareorep ) plus standard weekly paclitaxel (P) as therapy for metastatic breast cancer (mBC)

Background: Pelareorep is a Dearing strain of reovirus serotype 3, with demonstrated in vitro and in vivo activity in many cancers and synergistic cytotoxic activity with microtubule targeting agents, including taxanes. This study was designed to determine the efficacy and safety of pelareorep + P compared to P alone in mBC. Materials and Methods: This randomized, open-label, phase II study enrolled subjects who had mBC previously exposed to chemotherapy (CT). Subjects were randomized 1:1 between Arm A (P 80 mg/m2 day 1, 8 and 15 q 28 days plus pelareorep 3 x 1010 TCID50 day 1,2,8,9,15,16 q 28 days) and Arm B (P 80 mg/m2 day 1, 8 and 15 q 28 days). Treatment was continued until disease progression (PD) or unacceptable toxicity. Objective response was assessed every 8 weeks. Primary endpoint was progression free survival (PFS). The study had 90% power to detect an improvement of PFS from 4 to 7.5 months (HR 0.5, two-sided α=0.2). All p-values are two-sided. Results: Between July 2012 and April 2016, 81 subjects were accrued: 7 to the safety run-in for arm A, 36 to Arm A and 38 to Arm B. All had received prior CT, 59 as adjuvant treatment and 48 for mBC. Patients in Arm A had more favorable prognostic features, including lower LDH and less prior therapy. The median cumulative dose of P was 960 mg/m2 for arm A vs. 828 mg/m2 for arm B. Similar numbers of subjects in both arms required dose reductions, predominantly for myelosuppression. The median duration of treatment was 16.1 weeks for pelareorep and P in arm A and 14.1 weeks for P in arm B. With a median follow-up of 29.5 months, the median PFS was 3.78 mo for arm A and 3.38 mo for arm B (HR 1.04, 80% CI 0.76-1.43, p=0.87). Median OS was 17.4 mo for arm A and 10.4 mo for arm B (HR 0.65, 80% CI 0.46-0.91, p=0.1). Response rates (RR) were 25% for arm A and 23.7% for arm B (p=0.87). Pre-specified subset analysis found statistically significant differences in OS in patients with ECOG 1 or 2, aged &lt; 65 yr, and no prior P treatment. Exploratory analysis of biomarkers found significant differences in OS in patients with wild type PIK3CA, KIT, APC, PTEN, ATM, AKT1, mutated TP53, and both wild type and mutated MET, although the number of pts was small. When grade 3 or higher adverse events (AE) were considered, only the incidence of fatigue was found in ≥10% (16% on Arm A vs 13%, arm B, p=0.76). Hematologic grade 3 or higher effects observed in ≥10% patients included lymphopenia (5% arm A vs 18% arm B, p=0.08), and neutropenia (23% arm A vs 26% arm B; p=0.8). There was a statistically significant difference in grade 3 or higher LDH (0% arm A vs 13% arm B, p=0.03). There were no treatment related deaths. Conclusions: This first, phase II, randomized study of pelareorep + P vs P in mBC previously exposed to CT, did not meet its primary endpoint of PFS. Despite similar PFS and RR there was a statistically significant improvement in OS for pelareorep + P pts. Given these data, further exploration of the role of pelareorep + P in mBC may be of interest.

Citation Format: Vanessa Bernstein, Susan Ellard, Susan F. Dent, Karen A. Gelmon, Sukhbinder K. Dhesy-Thind, Mihaela Mates, Muhammed Salim, Lawrence Panasci, Xinni Song, Mark Clemons, Dongsheng Tu, Linda J. Hagerman, Lesley Seymour. A randomized (RCT) phase II study of oncolytic reovirus (pelareorep ) plus standard weekly paclitaxel (P) as therapy for metastatic breast cancer (mBC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT131. doi:10.1158/1538-7445.AM2017-CT131

Fulvestrant 500 mg versus anastrozole 1 mg for hormone receptor-positive advanced breast cancer (FALCON): an international, randomised, double-blind, phase 3 trial

BACKGROUND

Aromatase inhibitors are a standard of care for hormone receptor-positive locally advanced or metastatic breast cancer. We investigated whether the selective oestrogen receptor degrader fulvestrant could improve progression-free survival compared with anastrozole in postmenopausal patients who had not received previous endocrine therapy.

METHODS

In this phase 3, randomised, double-blind trial, we recruited eligible patients with histologically confirmed oestrogen receptor-positive or progesterone receptor-positive, or both, locally advanced or metastatic breast cancer from 113 academic hospitals and community centres in 20 countries. Eligible patients were endocrine therapy-naive, with WHO performance status 0-2, and at least one measurable or non-measurable lesion. Patients were randomly assigned (1:1) to fulvestrant (500 mg intramuscular injection; on days 0, 14, 28, then every 28 days thereafter) or anastrozole (1 mg orally daily) using a computer-generated randomisation scheme. The primary endpoint was progression-free survival, determined by Response Evaluation Criteria in Solid Tumors version 1·1, intervention by surgery or radiotherapy because of disease deterioration, or death from any cause, assessed in the intention-to-treat population. Safety outcomes were assessed in all patients who received at least one dose of randomised treatment (including placebo). This trial is registered with ClinicalTrials.gov, number NCT01602380.

FINDINGS

Between Oct 17, 2012, and July 11, 2014, 524 patients were enrolled to this study. Of these, 462 patients were randomised (230 to receive fulvestrant and 232 to receive anastrozole). Progression-free survival was significantly longer in the fulvestrant group than in the anastrozole group (hazard ratio [HR] 0·797, 95% CI 0·637-0·999, p=0·0486). Median progression-free survival was 16·6 months (95% CI 13·83-20·99) in the fulvestrant group versus 13·8 months (11·99-16·59) in the anastrozole group. The most common adverse events were arthralgia (38 [17%] in the fulvestrant group vs 24 [10%] in the anastrozole group) and hot flushes (26 [11%] in the fulvestrant group vs 24 [10%] in the anastrozole group). 16 (7%) of 228 patients in in the fulvestrant group and 11 (5%) of 232 patients in the anastrozole group discontinued because of adverse events.

INTERPRETATION

Fulvestrant has superior efficacy and is a preferred treatment option for patients with hormone receptor-positive locally advanced or metastatic breast cancer who have not received previous endocrine therapy compared with a third-generation aromatase inhibitor, a standard of care for first-line treatment of these patients.

FUNDING

AstraZeneca.

Abstract 268: PARP3 inhibitors in cancer therapy

Poly-ADP-ribose-polymerase (PARP1) is an important regulator of DNA damage response (DDR). After induction of certain types of DNA damage, including nicks and double strand breaks (DSB)s, PARP1 is rapidly recruited to altered DNA sites were its catalytic activity produces protein-conjugated long-branched-poly-ADP-ribose (PAR) chains. These protein modifications result in the recruitment and activation of multiple proteins involved in DNA repair. Although there is considerable research describing the characteristics and activity of PARP1/2, there are 15 other PARP family members that are less well characterized. Of these PARP3 has been shown to have a distinct role in DNA repair. This protein has been shown to have a critical role in DSB resolution and to interact with partner proteins know to function in classical nonhomologous end joining (NHEJ) such as DNA-PKcs, Ku70, and Ku80.

In order to examine the role of PARP3 vis-à-vis chemotherapy, we utilized the specific PARP3 inhibitor, ME-0328 in combination with activated cyclophosphamide (4HC) in the chronic lymphocytic leukaemia (CLL) cell lines, MEC1 and MEC2.

Results from MTT cytotoxicity assays showed that the 50% inhibitory concentration (IC50) (50% of control) of 4HC in MEC-1 cells was 12.9μM. When used in combination with a nontoxic concentration (2μM) of the specific PARP3 inhibitor ME-0328 the IC50 of 4HC was reduced to 3.3μM. In MEC-2 cells the IC50 of 4HC was 10.8μM and was reduced to 2.1μM in the presence of ME-0328 at 2μM. ABT-888, a specific PARP1/2 inhibitor in clinical trials had a minimal effect on 4HC cytotoxicity in these cell lines. 4HC results in interstrand crosslinks (ICLs) which are believed to be repaired by homologous recombination. Intriguingly, PARP3 negatively regulates class switch recombination via activation-induced cytidine deaminase in B-lymphocytes. This may be involved in ME-0328 sensitization of 4HC in B-lymphocytic malignancies.

Given these preliminary results we hypothesize that the PARP3 inhibitor, ME-0328 will sensitize B-lymphocytic cancers to chemotherapies. To explore this hypothesis this project will pursue the following objectives:

1. Characterize the selective sensitization of ME-0328 with 4HC and/or bendamustine (an ICL-inducing drug utilized in the treatment of B-lymphocyte malignancies) in B-lymphoma and CLL cell lines plus CLL clinical samples.

2. Determine the mechanisms by which ME-0328 sensitizes CLL cells to 4HC and/or bendamustine (i.e. reduction of PARP1 or 3 activity and/or altered activity of known DNA repair proteins (Rad51, DNA-PK, H2AX) and/or altered activation-induced cytidine deaminase).

3. Determine the in-vivo activity of 4HC and/or bendamustine with or without ME-0328 in a Rag2 /-γcc-/- xenograft model using the MEC1-CLL cell line.

The inhibition of PARP3 may increase the sensitivity of tumor cells to DNA damaging chemotherapies. Our results should stimulate development of specific PARP3 inhibitors for clinical use.

Citation Format: Bahram Sharif-Askari, David Davidson, Lilian Amrein, Lawrence Panasci. PARP3 inhibitors in cancer therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 268.

Complete response and long-term survival of leptomeningeal carcinomatosis from breast cancer with maintenance endocrine therapy

Leptomeningeal carcinomatosis carries a poor prognosis in breast cancer. Treatment modalities are geared towards tumour molecular characteristics, as well as symptoms and patient performance status. It has previously been postulated that endocrine treatments used for the treatment of metastatic breast cancer do cross the blood-brain barrier and can achieve antineoplastic effects in the central nervous system. We report a case of metastatic breast cancer in a 65-year-old woman who developed leptomeningeal carcinomatosis. She was initially treated with intrathecal methotrexate, which was stopped due to toxicity, followed by maintenance endocrine therapy. She achieved a sustained complete radiological and cerebrospinal fluid cytological response for over 9 years. She eventually passed away of ischaemic bowel unrelated to her cancer.

Altered Levels of Salivary 8-oxo-7-hydrodeoxyguanosine in Breast Cancer

Oxidative stress has been implicated in the pathogenesis of breast cancer (BC). To determine whether BC is associated with altered salivary redox homeostasis, we performed a case-control study assessing the relationship between BC and 8-oxo-7-hydrodeoxyguanosine (8-oxodG), a marker for oxidative damage to DNA. Enzyme-linked immunosorbent assay for 8-oxodG was used on whole, unstimulated saliva of 134 BC patients and 226 healthy controls. Associations of the redox data were assessed by analysis of variance and logistic regression analysis. Our results revealed that there were 1) significantly lower mean levels of salivary 8-oxodG in BC patients versus controls ( P = 0.0005), 2) significantly lower levels among participants who did not receive radiotherapy and/or chemotherapy as compared with controls ( P < 0.0001), 3) significantly lower levels among BC patients who did not receive these treatments than among those who did ( P < 0.02), 4) and no significant differences in mean 8-oxodG levels among BC patients positive or negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 ( P ≥ 0.08). Our results suggest that BC is associated with decreased levels of oxidatively modified DNA in saliva. Knowledge Transfer Statement: The results of our current case-control study indicate that the molecular biomarker of oxidative stress 8-oxo-7-hydrodeoxyguanosine, measured from saliva, is associated with breast cancer. Our findings may provide the basis for future studies on molecular biomarkers of oxidative stress and breast cancer using saliva as an accessible and noninvasive tissue.

Interferon-α/β enhances temozolomide activity against MGMT-positive glioma stem-like cells

Glioma is one of the most common primary tumors of the central nervous system in adults. Glioblastoma (GBM) is the most lethal type of glioma, whose 5-year survival is 9.8% at best. Glioma stem-like cells (GSCs) play an important role in recurrence and treatment resistance. MGMT is a DNA repair protein that removes DNA adducts and therefore attenuates treatment efficiency. It has been reported that interferon-α/β (IFN-α/β) downregulates the level of MGMT and sensitizes glioma cells to temozolomide. In the present study, we assessed whether IFN-α/β is able to sensitize GSCs to temozolomide by modulating MGMT expression. Upon the treatment of IFN-α/β, the efficacy of temozolomide against MGMT‑positive GSCs was markedly enhanced by combination treatment with IFN-α/β when compared with the temozolomide single agent group, and MGMT expression was markedly decreased at the same time. Further mechanistic study showed that IFN-α/β suppressed the NF-κB activity, which further mediated the sensitization of MGMT‑positive GSCs to temozolomide. Our data therefore demonstrated that the application of IFN-α/β is a promising agent with which to enhance temozolomide efficiency and reduce drug resistance, and our findings shed light on improving clinical outcomes and prolonging the survival of patients with malignant gliomas.

Abstract 5327: Simultaneous inhibition of ATR and PARP greatly sensitizes colon cancer cell lines to irinotecan

Enhanced DNA damage repair is one mechanism behind colon cancer drug resistance. Thus, targeting molecular components of repair pathways with specific small molecule inhibitors may improve the efficacy of chemotherapy. ABT-888 and VE-821, inhibitors of poly-ADP-ribose-polymerase (PARP) and the serine/threonine-kinase Ataxia telangiectasia related (ATR), respectively, were used to treat colon cancer cell lines in combination with the topoisomerase-I inhibitor irinotecan (SN38). Our findings show that each of these molecules at nontoxic single agent concentrations synergized with SN38 to produce a 2.2 to 3 fold reduction in the 50% inhibitory concentration (IC50) of SN38 (Table 1). When combined, nontoxic concentrations of ABT-888 and VE-821 produced a 4.5 to 27 fold reduction in the IC50 of SN38. Furthermore, the combination of all three agents was associated with maximal G2-M arrest and enhanced DNA-damage (γH2AX). The mechanism of this enhanced synergy was associated with maximal suppression of SN38 induced PARP activity in the presence of both inhibitors. Furthermore, VE-821 enhancement of SN38 induced DNA-PK phosphorylation was abrogated by ABT-888, resulting in more unrepaired DNA damage. This novel combination of DNA repair inhibitors may be useful to enhance the activity of DNA damaging chemotherapies such as irinotecan and help circumvent resistance to this drug in colon cancer.

Cell LineVE-821 (μM)ABT-888 (μM)SN38 (IC50) ± SE (nM)I valueP valueLoVo13.5±1.214.5±1.90.30.020.55.8±2.00.40.030.59.4±1.00.70.0610.53.0±1.20.20.010.50.54.7±1.90.40.02HCT-1168.1±0.713.5±0.50.50.010.55.2±0.60.70.030.53.9±1.10.50.0310.50.3±0.030.10.010.50.52.1±0.40.30.01HT-2920.5±1.819.3±0.60.60.010.512.2±1.30.70.020.512.9±0.70.60.0210.53.9±0.50.30.010.50.56.1±0.20.40.01

Table 1 Colon cancer cell lines LoVo, HCT-116 and HT-29 were treated with SN38 alone or in combination with various concentrations of the ATR inhibitor VE-821 and/or the PARP inhibitor ABT-888. The IC50 values of SN38 were significantly reduced in the presence of VE-821 and/or ABT-888 for all cell lines. Drug synergy (I) values were determined, according to Berenbaum (1978), by calculating the ratio:

(IC50 SN38 with inhibitors/IC50 SN38 alone) + (inhibitor concentration used/IC50 inhibitor alone); I less than 1 = synergism, I equal to 1 = additive effect and I greater than 1 = antogonism.

Citation Format: David Davidson, Atlal Abu-Sanad, Yunzhe Wang, Fatemeh Hasheminasab, Justin Panasci, Raquel Aloyz, Lawrence Panasci. Simultaneous inhibition of ATR and PARP greatly sensitizes colon cancer cell lines to irinotecan. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5327. doi:10.1158/1538-7445.AM2015-5327

Simultaneous inhibition of ATR and PARP sensitizes colon cancer cell lines to irinotecan

Enhanced DNA damage repair is one mechanism involved in colon cancer drug resistance. Thus, targeting molecular components of repair pathways with specific small molecule inhibitors may improve the efficacy of chemotherapy. ABT-888 and VE-821, inhibitors of poly-ADP-ribose-polymerase (PARP) and the serine/threonine-kinase Ataxia telangiectasia related (ATR), respectively, were used to treat colon cancer cell lines in combination with the topoisomerase-I inhibitor irinotecan (SN38). Our findings show that each of these DNA repair inhibitors utilized alone at nontoxic single agent concentrations resulted in sensitization to SN38 producing a 1.4–3 fold reduction in the 50% inhibitory concentration (IC₅₀) of SN38 in three colon cancer cell lines. When combined together, nontoxic concentrations of ABT-888 and VE-821 produced a 4.5–27 fold reduction in the IC₅₀ of SN38 with the HCT-116 colon cancer cells demonstrating the highest sensitization as compared to LoVo and HT-29 colon cancer cells. Furthermore, the combination of all three agents was associated with maximal G₂ −M arrest and enhanced DNA-damage (γH2AX) in all three colon cancer cell lines. The mechanism of this enhanced sensitization was associated with: (a) maximal suppression of SN38 induced PARP activity in the presence of both inhibitors and (b) ABT-888 producing partial abrogation of the VE-821 enhancement of SN38 induced DNA-PK phosphorylation, resulting in more unrepaired DNA damage; these alterations were only present in the HCT-116 cells which have reduced levels of ATM. This novel combination of DNA repair inhibitors may be useful to enhance the activity of DNA damaging chemotherapies such as irinotecan and help produce sensitization to this drug in colon cancer.

The trastuzumab and vinorelbine combination: an alternative to taxane-based chemotherapy for early-stage and locally advanced her2-positive breast cancer

BACKGROUND

Anthracyclines and taxanes have historically constituted the backbone of chemotherapy regimens for patients with breast cancer positive for the human epidermal growth factor receptor 2 (her2). For a subset of patients who categorically refuse alopecia, or for those with a contraindication to those drugs, there is an urgent need to define alternative regimens. Here, we report our institutional experience with trastuzumab and vinorelbine (tv), a combination with good clinical activity and a good side effect profile for patients with her2-positive breast cancer.

METHODS

In a retrospective analysis, outcomes data were extracted for patients receiving tv as their only chemotherapy in the non-metastatic setting at the Jewish General Hospital. For the most part, tv was administered weekly for 6 months, followed by trastuzumab for 6 months.

RESULTS

The analysis identified 46 patients (mean age: 64 years) who received tv between 2003 and 2012 (n = 36 adjuvant, n = 10 neoadjuvant). Of the patients in the adjuvant group, 81% had stage i disease. In the neoadjuvant group, 3 patients experienced a complete pathologic response. Only 1 patient experienced local recurrence after a short course (3 months) of adjuvant tv. Overall survival and breast cancer-specific survival were 94% and 98% respectively at a median 5 years of follow-up. Febrile neutropenia-induced sepsis resulted in the death of 1 patient with significant medical comorbidities; 2 other patients died of comorbidities unrelated to their cancer or treatment. Grades 3 or 4 adverse events included neutropenia (23%), febrile neutropenia (10%), fatigue (2%), and anemia (2%).

CONCLUSIONS

For patients with non-metastatic breast cancer refusing alopecia, or for patients who are not candidates for standard chemotherapy, tv is a reasonable alternative to standard adjuvant chemotherapy.

Abstract 1881: New therapeutic options for CLL treatment: Src/c-abl-directed molecular re-engineering of chlorambucil and bendamustine

B-cell chronic lymphocytic leukemia (CLL) is characterized by actively dividing B-lymphocytes in the lymph nodes and bone marrow, associated with the accumulation of quiescent lymphocytes in the peripheral blood of affected patients. Current treatments for this disease include chemotherapeutic (chlorambucil (CLB), cyclophosphamide, fludarabine) and immunotherapeutic agents (Rituximab, Alemtuzumab) or the combination of immunotherapy with chemotherapeutics drugs. In 2008, the FDA approved bendamustine, a bifunctional agent with a nitrogen mustard moiety and a purine analog, for the treatment of patients with CLL. Signals from the bone marrow and lymph node microenvironments protect CLL lymphocytes from drug-induced apoptosis. During treatment the enzyme-mediated repair of DNA damage can induce resistance to chemotherapeutic drugs. We have previously shown that small molecule inhibitors of c-abl (a key protein of the homologous recombinational repair pathway) such as imatinib, nilotinib or dasatinib, sensitize primary CLL lymphocytes to CLB. We also demonstrated that ZRF4, a combi-molecule designed to target c-abl (through an imatinib moiety) and to induce DNA damage (through a nitrogen mustard moiety), has a more potent cytotoxic effect than the combination of CLB plus imatinib in CLL lymphocytes. Here we report the anticancer effect of three different combi-molecules composed of a chlorambucil moiety and a dasatinib (a dual Src/c-abl inhibitor) moiety compare to the individual components in primary CLL lymphocytes in-vitro. Using MTT assays on CLL lymphocytes from 40 CLL patients, we found that the IC50 (concentration which kills 50% of the cells) of AL748, AL758 and AL816 are significantly lower than the IC50 of CLB when used alone and the combination of CLB with 0.1 μM dasatinib (median value = 1.7 μM, 0.6 μM, 0.9 μM, 11 μM and 3.1 μM respectively). Moreover, our biochemical results suggest that the mechanism of action of AL758, AL816, CLB and CLB plus dasatinib share common downstream targets including inhibition of Src kinase, chemotaxis, and cross-talk with the microenvironment along with induction of DNA damage (p53, p21, comet assay) and apoptosis (AnnexinV, cleaved caspase-3). We also determined, by the MTT assay, the cytotoxic effect of the combi-molecule AL887 composed of a bendamustine moiety and a dasatinib moiety, compare to the individual components in vitro in primary B-lymphocytes from 20 CLL patients. Our results demonstrated that this combi-molecule has a better anticancer activity than bendamustine in combination with 0.1 μM dasatinib (p&lt;0.0005).

Dose-limiting toxicity and drug pharmacokinetics are important and limiting factors to take into account for the development of chemotherapy and will be tested in a CLL mouse model. Our results suggest that the combi-molecules AL758, AL816, and AL887 may be useful alternatives for treatment of CLL patients.

Citation Format: Lilian Amrein, Anne-Laure Larocque, David Davidson, Lisa Peyrard, Daniel Borrelli, Bertrand Jean-Claude, Lawrence Panasci. New therapeutic options for CLL treatment: Src/c-abl-directed molecular re-engineering of chlorambucil and bendamustine. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1881. doi:10.1158/1538-7445.AM2014-1881

Hormonal manipulation with letrozole in the treatment of metastatic malignant pecoma

Perivascular epithelioid cell tumours (pecomas) are rare mesenchymal tumours. Some have a benign course; others metastasize. Treatment of malignant pecomas is challenging, and little is known about treatment for patients with metastatic disease. Here, we report a case of metastatic malignant pecoma with estrogen and progesterone receptor expression that showed a favourable and sustained response to letrozole.

Aromatase inhibition in relapsing low malignant potential serous tumours of the ovary

Low malignant potential serous tumours (LMPSTs) of the ovary represent an indolent disease, with an excellent prognosis in a majority of patients. Patients with recurrent LMPSTs tend to develop widespread disease with a mortality rate as high as 70%. These tumours tend to have a very poor response to standard chemotherapy, and the management of primary and recurrent disease beyond surgical resection is not well defined. The majority of LMPST have been reported to express oestrogen and progesterone hormone receptors. However, only three reported cases of antihormonal treatment in this setting, and only one using aromatase inhibitors (AI), have been previously reported. We herein report long-term complete remission of two patients with relapsed, chemotherapy-resistant LMPSTs, treated with long-term AI (anastrozole 1 mg daily) as per negative MRI and positron emission tomography scans. Our results warrant further investigation for the use of AIs for metastatic recurrent LMPSTs.

Effects of dna-dependent protein kinase inhibition by NU7026 on dna repair and cell survival in irradiated gastric cancer cell line N87

Repair of radiation-induced dna double-strand breaks is a key mechanism in cancer cell radio-resistance. The synthesized compound NU7026 specifically inhibits dna-dependent protein kinase (dna-pk) within the non-homologous end-joining repair mechanism. Earlier studies demonstrated increased radiosensitivity in dna-pk deficient cells compared with wild-type cells. In chronic leukemia cells, NU7026 appears to enhance the cytotoxic effect of chlorambucil. The radio-modifying effects of NU7026 on cell survival, cell cycle, apoptosis, and dna double-strand break repair have yet to be studied in gastric cancer cells.

METHODS

The gastric cancer cell line N87 was treated with 0 Gy or 4 Gy in the presence of NU7026 at a dose range of 0-20 μmol/L. Clonogenic assays were used to assess cell survival after treatment. Cell-cycle distribution was analyzed using propidium iodide with fluorescence-activated cell sorting. Apoptosis was detected using annexin-V and propidium iodide with fluorescence-activated cell sorting. The γH2AX assay was used to measure dna double-strand breaks.

RESULTS

Statistically significant increases in G2/M arrest were observed in N87 cells treated with radiation and NU7026 compared with those treated with radiation alone (p = 0.0004). Combined treatment also led to an increase in apoptosis (p = 0.01). At 24 hours, the γH2AX analysis revealed more dna double-strand breaks in N87 cells treated with radiation and NU7026 than in those treated with radiation alone (p = 0.04). Clonogenic assays demonstrated declining cell survival as both the radiation and the NU7026 dose increased. The dose enhancement factor at 0.1 survival fraction was 1.28 when N87 cells were treated with 4 Gy radiation and 5 μmol/L NU7026.

CONCLUSIONS

In gastric cancer cells, NU7026 appears to enhance the cytotoxic effect of irradiation as assessed by clonogenic assays. This increased cytotoxicity might be the result of an increase in dna double-strand breaks resulting in G2/M cell arrest and possibly higher levels of apoptosis.

Are XELOX and FOLFOX equivalent in colorectal cancer? Dose intensity, toxicity, and treatment duration in clinical practice

e14556

Background: Xelox and Folfox regimens have been shown to be equivalent in clinical trials for colorectal cancers. However, concerns about toxicity induced by Xelox in clinical practice have been reported, resulting in reduced dose intensity. In this retrospective analysis, we compared the dose intensity of Xelox to Folfox in relation to toxicity. Methods: 208 patients were treated in adjuvant (Xelox: n=56, median age 65 years; Folfox: n=40, median age 66 years) or metastatic (Xelox: n=65, median age 66 years; Folfox: n=47 median age 62 years) settings. 90% of patients had ECOG 0-1. Results: In the adjuvant setting, 86% of patients treated with Xelox received a lower dose of the drug up front, compared to only 10% of Folfox-treated patients. Additional dose reductions occurred in subsequent cycles in 23% of Xelox-treated patients (mean relative dose intensity (RDI) Oxaliplatin: 72%; Capecitabine: 74%) but not Folfox-treated patients (mean RDI Oxaliplatin: 85%, 5-FU: 86%). A higher percentage of Folfox-treated patients had toxicities compared to Xelox-treated patients: nausea (30% vs 18%), diarrhea (47% vs 24%), and peripheral sensory neuropathy (32% vs 3%). Treatment delays were more frequent in Folfox (40%); mean cumulative delay, 9.4 (range 2.1-52.4) weeks, compared to Xelox (20%); mean cumulative delay, 10.2 (3.1-48.1) weeks. Mean treatment duration was equal (Xelox: 22.8 (3.0-78.1); Folfox: 22.6 (2.3-64.4) weeks). In the metastatic setting, results followed a similar pattern. 75% of Xelox-treated patients received a lower dose up front compared to 33% of Folfox-treated patients. Further dose reductions occurred in 31% of Xelox-treated patients (mean RDI Oxaliplatin: 70%; Capecitabine: 67%) compared to 20% of Folfox-treated patients (mean RDI oxaliplatin: 75%; 5-FU: 69%). Treatment delays occurred in 60% of Folfox-treated patients and 43% of Xelox-treated patients becauseof toxicities. Mean treatment duration was 24.9 (3.0-65.0) and 26.1 (4.0-60.1) weeks respectively. Conclusions: The higher dose reduction of Xelox compared to Folfox appeared to enable treatment completion with less toxicities. The impact on survival and cost of treatments will be presented.

Systemic cancer therapy: achievements and challenges that lie ahead

In the last half of the century, advances in the systemic therapy of cancer, including chemotherapy, hormonal therapy, targeted therapy, and immunotherapy have been responsible for improvements in cancer related mortality in developed countries even as the population continues to age. Although such advancements have yet to benefit all cancer types, systemic therapies have led to an improvement in overall survival in both the adjuvant and metastatic setting for many cancers. With the pressure to make therapies available as soon as possible, the side-effects of systemic therapies, in particular long-term side-effects are not very well characterized and understood. Increasingly, a number of cancer types are requiring long-term and even lifelong systemic therapy. This is true for both younger and older patients with cancer and has important implications for each subset. Younger patients have an overall greater expected life-span, and as a result may suffer a greater variety of treatment related complications in the long-term, whereas older patients may develop earlier side-effects as a result of their frailty. Because the incidence of cancer in the world will increase over the next several decades and there will be more people living with cancer, it is important to have an understanding of the potential side-effects of new systemic therapies. As an introductory article, in this review series, we begin by describing some of the major advances made in systemic cancer therapy along with some of their known side-effects and we also make an attempt to describe the future of systemic cancer therapy.

Abstract B13: ATR and PARP inhibition enhances topoisomerase I-dependent DNA damage in colon cancer cell lines

Introduction: The understanding of DNA repairs pathways and their interactions allowed for the development of several targeted therapies, which sensitize neoplastic cells to the effects of DNA damaging chemotherapy. Poly-ADP ribose polymerase (PARP) inhibitors can increase the cytotoxicity of several anticancer agents by inhibiting various DNA repair pathways including Rad51 related homologous recombinational repair (HRR). However, inhibition of PARP may result in compensatory activation of the ATR pathway partially limiting the sensitization of chemotherapeutic agents seen with PARP inhibitors. Recently, a specific ATR inhibitor, VE-821 has demonstrated excellent sensitization to various chemotherapeutic agents with preferential antitumor activity in tumor cells as compared to normal cells (Reaper PM et al Nature Chem Biol 7: 428-30, 2011)

Colon cancer cell lines: HCT116/Lovo (p53 wild type) and HT29 (p53 mutated) were treated with SN38, the PARP inhibitor (ABT-888) and/or the ATR inhibitor (VE821) at different concentrations. The SRB cytotoxicity assay was used to determine the IC50 of each drug separately and in combination. DNA damage caused by these agents was quantified by phosphorylated-H2AX. Cell cycle alterations and protein levels (western analysis) were determined after drug treatment.

Results: Nontoxic concentrations (0.5-1 μM) of ABT-888 or VE-821 demonstrated a two to three fold decrease in the IC50 of SN38 in the colon cancer cell lines. Significantly, the combination of both inhibitors at the same nontoxic concentrations resulted in a dramatic 4 to 25-fold decrease in the IC50 of SN38 [HCT116 (8.1 nM to 0.3 nM), HT29 (20.5 nM to 3.9 nM) and Lovo (13.5nM to 3 nM)]. Notably, the observed effect was dose-dependent. In the Lovo cell line, the combination of SN38/VE821/ABT888 increased G2/M cell cycle arrest compared to SN38/VE821, SN38/ABT888 and SN38 alone. Similarly, increased phosphorylated-H2AX and apoptosis were seen with SN38/VE821/ABT888 in the Lovo and HCT-116 cell lines. Preliminary data utilizing the annexin-5 apoptosis assay in the HCT116 cell line supports the increased cell killing by the combination of all three agents. In the HCT116 cell line, treated with the SN38/VE821/ABT888 combination as compared to cells treated with SN38 alone, increased expression of p21 along with decreased expression of phospho-Chk1 was observed.

Conclusion: The SN38/ABT888/VE821 combination resulted in maximal synergy/chemosensitivity in all colon cancer cell lines, associated with increased DNA damage and apoptosis. Our data suggests that this combination may effectively overcome colon cancer resistance to irinotecan-based chemotherapy.

Citation Format: Atlal Abu-Sanad, David Davidson, Yunzhe Wang, John Pollard, Raquel Aloyz, Lawrence Panasci. ATR and PARP inhibition enhances topoisomerase I-dependent DNA damage in colon cancer cell lines. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B13.

Abstract 932: Predictive markers of the in vitro anticancer effect of the pan class I PI3K inhibitor BKM120 in primary B-CLL lymphocytes

B-chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD5+ B-lymphocytes that are long-lived in-vivo but die quickly by apoptosis when cultured in-vitro. The phosphatidylinositol-3 kinase (PI3K) cascade which is a critical component of survival signaling has increased activity in CLL lymphocytes as compared to normal B lymphocytes. There are three classes of PI3Ks of which class I is the most clearly implicated in human cancer. The PI3K-δ inhibitor, CAL-101, promotes apoptosis and abrogated protection from spontaneous apoptosis induced by CD40 in primary CLL lymphocytes in-vitro. Thus the PI3K pathway appears to play a critical role in B-CLL cell survival. BKM120 is a pan class I PI3K inhibitor developed by Novartis. Phase I trials demonstrated that plasma concentrations (Cmax) of 5 μM can be obtained. In view of the critical role of PI3K in CLL homeostasis, the activity of BKM120 was examined in CLL lymphocytes in-vitro. BKM120 was cytotoxic in the 3 CLL cell lines and in 78% of the primary B-CLL lymphocytes samples isolated from 65 B-CLL patients, including patients with del11 and del17. Interestingly, 60% of the B-CLL samples tested in our study have an IC50 below the Cmax. Furthermore, BKM120 cytotoxicity correlated with the basal expression of proteins involved in the PI3K/Akt pathway (Akt, rictor, raptor, p70S6K and 4E-BP1) but not with PTEN, mTor, IgVH or CD38 expression in these primary B-CLL lymphocytes. Further analysis of these different markers demonstrated that only patients very sensitive to BKM120 (IC50 ≤3 μM) expressed low basal levels of mTor, raptor and p70S6K simultaneously. Inhibition of PI3K was demonstrated by detection of phosphorylated Akt (S473) after BKM120 treatment in the cell lines. Molecular biomarkers such as p70S6K and 4E-BP1 have been used as indicators of PI3K pathway inhibition in-vivo. We also have demonstrated that BKM120 decreased the phosphorylation status of 4E-BP1 and p70S6K in the primary B-CLL lymphocytes tested. As detected by AnnexinV/propidium iodine staining and analysis of caspase-3 cleavage, BKM120 induced apoptosis in primary B-CLL cells culture in the presence and absence of stromal cell support.

Taken together, our results demonstrated that the class I PI3K inhibitor BKM120 may be useful as a single agent in CLL patients independently of their IgVh mutational status, CD38 expression or genomic deletions (del11 and del17). Furthermore, a combination of different biomarkers (expression of mTor, raptor, and p70S6K) may predict the response to BKM120 treatment. Also, BKM120 abolished the protection against apoptosis and drug resistance conferred by the microenvironment to the primary B-CLL lymphocytes in-vitro. Our preclinical study demonstrated that BKM120, a molecule with acceptable clinical toxicity, may be useful in the treatment for CLL.

Citation Format: Lilian Amrein, May Shawi, Jeremy Grenier, Raquel Aloys, Lawrence Panasci. Predictive markers of the in vitro anticancer effect of the pan class I PI3K inhibitor BKM120 in primary B-CLL lymphocytes. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 932. doi:10.1158/1538-7445.AM2013-932

A real-life experience using panitumumab in chemo-refractory metastatic colorectal cancer patients: a retrospective analysis at the Jewish General Hospital, 2009-2012

BACKGROUND

Panitumumab is a fully human monoclonal antibody, directed against the epidermal growth factor receptor, that was shown to be effective in third-line metastatic colorectal cancer. We performed a retrospective analysis of patients with chemo-refractory non-KRAS-mutated metastatic colorectal cancer, who received panitumumab at the Jewish General Hospital in Montreal, Canada, between 2009 and 2012.

METHODS

This chart review included 44 patients (median age: 60 years; performance status: 0-3), of whom 50% had already received three lines of treatment. The primary endpoint was progression-free survival (pfs). Secondary endpoints were overall survival and safety. Tumour progression was determined by radiologic assessments performed once every 3 months per clinical guidelines or by clinical deterioration as determined by the clinician-investigator.

RESULTS

In our sample, median pfs was 21.86 ± 5.23 weeks (95% confidence interval: 12.9 to 36.9 weeks) and overall survival was 35.14 ± 7.75 weeks (95% confidence interval: 25.6 to 73.4 weeks) with a median of 5 cycles of panitumumab treatment. The most frequently reported toxicities with panitumumab were skin toxicity (16.2% grade 3) and hypomagnesemia (10.8% grade 3). No infusion reactions were reported.

CONCLUSIONS

Despite a small sample size from a single institution, our survival and efficacy data are encouraging and comparable to results obtained from the registration panitumumab trial. Our findings suggest that panitumumab can be effective and tolerable in a real-world setting.

The PARP inhibitor ABT-888 synergizes irinotecan treatment of colon cancer cell lines

Poly [ADP-ribose] polymerase-1 (PARP-1) localizes rapidly to sites of DNA damage and has been associated with various repair mechanisms including base excision repair (BER) and homologous recombination/non-homologous end joining (HRR/NHEJ). PARP-1 acts by adding poly-ADP ribose side chains to target proteins (PARylation) altering molecular interactions and functions. Recently small molecule inhibitors of PARP-1 have been shown to have significant clinical potential and third generation PARP inhibitors are currently being investigated in clinical trials. These drugs alone or in combination with radio/chemotherapy have resulted in meaningful patient responses and an increase in survival in metastatic breast cancer cases bearing BRCA-deficient or triple negative tumors and BRCA-deficient ovarian cancer patients. ABT-888, a potent PARP-1 inhibitor, sensitizes many cancer cells in-vitro and in-vivo to temozolomide. As such, we hypothesized that colon cancers would be sensitized to the DNA damaging chemotherapeutic agents, oxaliplatin and irinotecan, by ABT-888. Using colon cancer cell lines significant synergy was observed between ABT-888 and irinotecan at concentrations of ABT-888 as low as 0.125 μM. The level of synergy observed correlated with the degree of PARP1 inhibition as measured biochemically in cell lysates. ABT-888 at concentrations of 0.5-4 μM resulted in synergy with oxaliplatin. Furthermore, 24 h post treatment combinations of ABT-888/irinotecan generally resulted in increased G2/M cell cycle arrest and increased levels of DNA damage, followed by increased levels of apoptosis 48 h post treatment. In conclusion this study suggests that ABT-888 may be a clinically effective adjuvant to current colon cancer therapies that include the use of irinotecan and/or oxaliplatin.

Small Molecules, Inhibitors of DNA-PK, Targeting DNA Repair, and Beyond

Many current chemotherapies function by damaging genomic DNA in rapidly dividing cells ultimately leading to cell death. This therapeutic approach differentially targets cancer cells that generally display rapid cell division compared to normal tissue cells. However, although these treatments are initially effective in arresting tumor growth and reducing tumor burden, resistance and disease progression eventually occur. A major mechanism underlying this resistance is increased levels of cellular DNA repair. Most cells have complex mechanisms in place to repair DNA damage that occurs due to environmental exposures or normal metabolic processes. These systems, initially overwhelmed when faced with chemotherapy induced DNA damage, become more efficient under constant selective pressure and as a result chemotherapies become less effective. Thus, inhibiting DNA repair pathways using target specific small molecule inhibitors may overcome cellular resistance to DNA damaging chemotherapies. Non-homologous end joining a major mechanism for the repair of double-strand breaks (DSB) in DNA is regulated in part by the serine/threonine kinase, DNA dependent protein kinase (DNA-PK). The DNA-PK holoenzyme acts as a scaffold protein tethering broken DNA ends and recruiting other repair molecules. It also has enzymatic activity that may be involved in DNA damage signaling. Because of its’ central role in repair of DSBs, DNA-PK has been the focus of a number of small molecule studies. In these studies specific DNA-PK inhibitors have shown efficacy in synergizing chemotherapies in vitro. However, compounds currently known to specifically inhibit DNA-PK are limited by poor pharmacokinetics: these compounds have poor solubility and have high metabolic lability in vivo leading to short serum half-lives. Future improvement in DNA-PK inhibition will likely be achieved by designing new molecules based on the recently reported crystallographic structure of DNA-PK. Computer based drug design will not only assist in identifying novel functional moieties to replace the metabolically labile morpholino group but will also facilitate the design of molecules to target the DNA-PKcs/Ku80 interface or one of the autophosphorylation sites.

The phosphatidylinositol-3 kinase I inhibitor BKM120 induces cell death in B-chronic lymphocytic leukemia cells in vitro

BKM120, a pan class I PI3K inhibitor, was cytotoxic in the majority of primary B-chronic lymphocytic leukemia (CLL) lymphocytes, including samples from patients who have a high-risk for poor response to treatment (patient with del11 and del17) at clinically obtainable concentrations. The PI3Kδ inhibitor Cal-101 is cytotoxic in B-CLL lymphocytes in vitro and is active in the treatment of CLL in vivo. Interestingly, we demonstrated that BKM120 is 3.6 fold more toxic than Cal-101 in malignant B-CLL lymphocytes in vitro. BKM120 cytotoxicity correlated with the basal expression of proteins involved in the PI3K/Akt pathway. A protein signature of PI3K pathway proteins predicts the response to BKM120 treatment. In the primary B-CLL lymphocytes tested in vitro, BKM120 decreased the phosphorylation status of molecular biomarkers used as indicators of PI3K pathway inhibition in vivo. Also, BKM120 induced apoptosis in primary B-CLL cells culture in the presence and absence of stromal cell support. Our findings suggest that BKM120 should be tested clinically in CLL.

Is there an epigenetic component underlying the resistance of triple-negative breast cancers to parp inhibitors?

Poly(ADP-ribose) polymerase (Parp) is an enzyme responsible for catalyzing post-translational modifications through the addition of poly(ADP-ribose) chains (known as PARylation). Modification by PARylation modulates numerous cellular processes including transcription, chromatin remodeling, apoptosis, and DNA damage repair. In particular, the role of Parp activation in response to DNA damage has been intensely studied. Tumors bearing mutations of the breast cancer susceptibility genes, Brca1/2, are prone to DNA breakages whose restoration into functional double-strand DNA is Parp dependent. This concept has been exploited therapeutically in Brca mutated breast and ovarian tumors, where acute sensitivity to Parp inhibitors is observed. Based on in vitro and clinical studies it remains unclear to what extent Parp inhibitors can be utilized beyond treating Brca mutated tumors. This review will focus on the often overlooked roles of PARylation in chromatin remodeling, epigenetics, and transcription to explain why some cancers may be unresponsive to Parp inhibition. We predict that understanding the impact of PARylation on gene expression will lead to alternative approaches to manipulate the Parp pathway for therapeutic benefit.

Abstract B24: De novo and acquired resistance to first-line standard therapy in colorectal cancer: from cell lines to metastatic tumors

Introduction: Personalized medicine (PM) is a concept that has raised high expectations amongst scientists, clinicians, and patients. An emerging approach is to examine tumor biopsy material for genomic changes that are known targets of currently available therapeutic agents, with the assumption that a clinical benefit will be observed if the target is inhibited. While striking anecdotal reports are predictable from this approach, the clinical impact of these agents is limited by the inevitable development of therapeutic resistance. Our focus is on the design of parallel research programs using both in vitro and in vivo strategies, in an effort to delay or inhibit resistance. We present here preliminary data for a signature of resistance to standard first-line treatment - fluorouracil, folinic acid, oxaliplatin and bevacizumab (FOLFOX/B) using cell line models of resistance to this regimen. In parallel, we are conducting a prospective study to identify biomarkers of clinical resistance to first-line therapy in patients with metastatic colorectal cancer (CRC) (NCT00984048).

Methods: Ten established CRC cell lines were treated with FOLFOX/B and categorized as resistant or sensitive based on IC50 values. In parallel, patients who consented to an initial biopsy and one at disease progression following an initial response were identified as intrinsically resistant or as having acquired resistance during treatment. CRC cell lines that were initially sensitive were rendered resistant to mimic the acquired resistance in patients, by serial passages with gradual increases in concentration of the combination regimen. We compared microarray data from three sensitive and three resistant cell lines.

Results: We found a different expression pattern from microarray data comparing sensitive and resistant cell lines, thereby indicating a potential signature of resistance to FOLFOX/B. Interestingly, we found that the Src family kinase Lyn was overexpressed in resistant cells lines. Treating cells with non-cytotoxic concentration of dasatinib, a dual Src family kinase and Abl inhibitor, sensitized both the parental sensitive cells and the cells with acquired resistance to FOLFOX/B, thereby suggesting that combination treatment with dasatinib may be effective in delaying or inhibiting resistance. We have thus far collected needle core biopsies from liver metastases from forty patients who agreed to partake in this multi-center trial. Eligible patients have confirmed metastatic CRC, measurable disease, and consent to three needle-core biopsies (NCBs) of a non-resectable liver metastasis before treatment and at resistance, as well as serial blood collection throughout the study. Using standard operating procedures developed for this trial, we were able to both preserve morphology and obtain high-quality genomic material from biopsy tissue. We will determine if the resistance signature and overexpression of Lyn observed in the resistant CRC cell lines are similarly demonstrated in patients that were intrinsically resistant to FOLFOX/B.

Conclusions: We have designed parallel in vitro and in vivo experiments to study resistance to standard first-line treatment for mCRC. These studies provide insight on metastatic signatures of resistance and suggest combination therapies to delay or inhibit therapeutic resistance in patients.

Abstract 5534: Building the organization framework for biopsy-driven translational research: The Quebec Clinical Research Organization in Cancer (Q-CROC) experience

Introduction: The success of personalized medicine in oncology relies on translational research efforts to identify biomarkers that will influence clinical management. The discovery and validation of biomarkers is a concerted effort requiring an organizational framework that is often underestimated. The Quebec Clinical Research Organization in Cancer (Q-CROC) consortium is a multi-disciplinary and multi-institutional group of scientists and clinicians devoted to integrating and enhancing translational and clinical research capacity in Quebec. We describe here the organizational framework driving a multicenter, prospective study to identify biomarkers of clinical resistance to first-line therapy in metastatic colorectal cancer (NCT00984048, Q-CROC-01). Results: The Q-CROC consortium has put in place an organizational infrastructure to support the activities and operations of its translational projects. We identified and addressed several critical issues during the course of the Q-CROC-01 translational project that were also common to our subsequent biomarker-driven trial in lymphoma (Q-CROC-02, NCT01238692) and breast cancer (Q-CROC-03, NCT01276899). Examples of these issues include: (i) feasibility and burden of tissue collection at participating sites, (ii) limiting pre-analytical variability in blood and tissue specimens for functional downstream applications, (iii) verification of tumor content on biopsy specimens, (iv) tracking sample flow, (v) integration of clinical data with discovery platforms, and (vi) engaging participation throughout all steps of the project. In part to address the above issues, we established five operational Cores: clinical, biobank, biospecimen processing, bioanalytical and bioinformatic. A further challenge was the integration between these Cores, who for the most part operated in silos. We observed that a critical element to unify all components of the consortium was a scientific project management team, consisting of dedicated individuals regularly interacting with each Core to ensure that objectives were aligned and deliverables were met. This academic framework for translational research may be comparable to that of multicenter clinical trials undertaken by industry, but some challenges, including financial and time constraints, data sharing and IP agreements, and engagement of its members, may be more palpable in the academic setting. Conclusion: Infrastructure science is underestimated and under-reported in translational cancer research and is crucial to the success of any large-scale biomarker discovery effort. Our experience with three multi-institutional biomarker-driven trials is that progress hinges upon the availability of an infrastructure that is not only the sum of its parts but that provides a concrete link between each component.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5534. doi:1538-7445.AM2012-5534

Irinotecan and DNA-PKcs inhibitors synergize in killing of colon cancer cells

This study sought to measure the degree of synergy induced by specific small molecule inhibitors of DNA-PK [NU7026 and IC486241 (ICC)], a major component of the non-homologous end-joining (NHEJ) pathway, with SN38 or oxaliplatin. Synergy between the DNA damaging drugs and the DNA-PK inhibitors was assessed using the sulforhodamine-B assay (SRB). Effects of drug combinations on cell cycle and DNA-PK activity were determined using flow cytometry and western blot analysis. DNA damage was assessed via comet assay and quantification of γH2AX. The role of homologous recombination repair (HRR) was determined by nuclear Rad51 protein levels and a GFP reporter recombination assay. Significant reductions in the IC(50) values of SN38 were observed at 5 and 10 μM of DNA-PK inhibitors. Moreover, at 1-2 μM (attainable concentrations with ICC in mice) these DNA-PKcs inhibitors demonstrated synergistic reductions in the IC(50) of SN38. Flow cytometric data indicated that SN38 and SN38 in combination with DNA-PKcs inhibitors showed dramatic G2/M arrest at 24 h. Furthermore, reduced phosphorylation of DNA-PKcs and increased DNA damage were observed at this time point with SN38 in combination with DNA-PKcs inhibitors as compared to cells treated with SN38 alone. SN38 alone and in the presence of ICC increased nuclear Rad51 protein levels. Furthermore, inhibition of DNA-PKcs increased HRR suggesting that NHEJ is a negative regulator of HRR. These data indicate that small molecule inhibitors of DNA-PKcs dramatically enhance the efficacy of SN38 in colon cancer cell lines.

Results of a phase II study comparing three dosing regimens of fulvestrant in postmenopausal women with advanced breast cancer (FINDER2)

The Faslodex Investigation of Dose evaluation in Estrogen Receptor-positive advanced breast cancer (FINDER)2 study evaluated the efficacy, safety, and pharmacokinetics (PK) of three fulvestrant dosing regimens. FINDER2 enrolled Western postmenopausal women recurring or progressing after prior endocrine therapy. Primary endpoint: objective response rate (ORR); secondary endpoints: time to progression (TTP), clinical benefit rate (CBR), tolerability, and PK parameters. Patients were randomized to receive fulvestrant: 250 mg/month (approved dose [AD]); 250 mg plus loading dose (loading dose [LD]; 500 mg on day 0, 250 mg on days 14, 28, and monthly thereafter); or 500 mg (high dose [HD]; 500 mg/month plus 500 mg on day 14 of Month 1). Treatment continued until disease progression or discontinuation. 144 patients were randomized: fulvestrant AD (n = 47); LD (n = 51); HD (n = 46). ORRs were: 8.5% (95% confidence interval [CI]: 2.4, 20.4%), 5.9% (1.2, 16.2%), and 15.2% (6.3, 28.9%) in the AD, LD, and HD arms, respectively. CBRs were: 31.9% (95% CI: 19.1, 47.1%), 47.1% (32.9, 61.5%), and 47.8% (32.9, 63.1%) for the AD, LD, and HD arms, respectively. Median TTP (months) was numerically longer for HD (6.0) and LD (6.1) versus AD (3.1). Tolerability was similar across dosing regimens. Steady-state plasma fulvestrant concentrations were predictable and achieved earlier with LD and HD. While there appeared to be a trend toward improved efficacy with HD and LD versus AD, no significant differences could be shown. A parallel study (FINDER1) has reported similar findings in Japanese patients.

Metformin blocks the stimulative effect of a high-energy diet on colon carcinoma growth in vivo and is associated with reduced expression of fatty acid synthase

The molecular mechanisms responsible for the association of obesity with adverse colon cancer outcomes are poorly understood. We investigated the effects of a high-energy diet on growth of an in vivo colon cancer model. Seventeen days following the injection of 5x10(5) MC38 colon carcinoma cells, tumors from mice on the high-energy diet were approximately twice the volume of those of mice on the control diet. These findings were correlated with the observation that the high-energy diet led to elevated insulin levels, phosphorylated AKT, and increased expression of fatty acid synthase (FASN) by the tumor cells. Metformin, an antidiabetic drug, leads to the activation of AMPK and is currently under investigation for its antineoplastic activity. We observed that metformin blocked the effect of the high-energy diet on tumor growth, reduced insulin levels, and attenuated the effect of diet on phosphorylation of AKT and expression of FASN. Furthermore, the administration of metformin led to the activation of AMPK, the inhibitory phosphorylation of acetyl-CoA carboxylase, the upregulation of BNIP3 and increased apoptosis as estimated by poly (ADP-ribose) polymerase (PARP) cleavage. Prior work showed that activating mutations of PI3K are associated with increased AKT activation and adverse outcome in colon cancer; our results demonstrate that the aggressive tumor behavior associated with a high-energy diet has similar effects on this signaling pathway. Furthermore, metformin is demonstrated to reverse the effects of the high-energy diet, thus suggesting a potential role for this agent in the management of a metabolically defined subset of colon cancers.

Are frailty markers useful for predicting treatment toxicity and mortality in older newly diagnosed cancer patients? Results from a prospective pilot study

INTRODUCTION

The concept of frailty may be useful to characterize vulnerability. The aim of this pilot study was to explore the association between frailty/functional status and treatment toxicity at 3 months and mortality at 6 months.

METHODS

Patients aged ≥65 years referred to the Jewish General Hospital, Montreal, with a new cancer diagnosis. Seven frailty markers and 4 functional status measures were examined. Logistic regression was used to examine the association between frailty/functional status and toxicity, and Cox models for time to death.

RESULTS

112 participated, median age 74.1, 31 had toxicity and 15 died. At baseline, 88% had ≥1 frailty marker. Low grip strength predicted toxicity (OR 8.47, 95%CI: 1.3-53.6), ECOG performance status and ADL disability predicted time to death.

CONCLUSION

The majority had ≥1 frailty marker. Low grip strength predicted toxicity, none of the functional measures did. Further researcher investigating the usefulness of frailty markers is needed.

Abstract LB-100: Optimal modulation of DNA repair in CLL therapy

Resistance to chlorambucil (CLB) in chronic lymphocytic leukemia (CLL) can occur as a consequence of increased DNA repair including c-abl stimulated Rad-51 related homologous recombinational repair (HRR) and DNA-PK related nonhomologous endjoining (NHEJ).

Recent reports suggest that the nonreceptor tyrosine kinase c-abl plays an important role in CLL. In particular, we have previously demonstrated that imatinib inhibition of c-abl or NU7026 inhibition of DNA-PK in CLL lymphocytes results in sensitization to CLB in most samples. Here we report that nilotinib, a superpotent (20-30 fold greater than niltinib) inhibitor of c-abl is more efficacious than imatinib in sensitizing CLL lymphocytes to CLB in the majority of the CLL lymphocyte samples associated with a greater nilotinib related inhibition of c-abl autophosporylation, increased apoptosis and decreased repair of CLB-induced DNA damage (increased activated H2AX).

Furthermore, in CLL samples in which c-abl was inhibited by either inhibitor, there was an increased activation of DNA-PK. Utilizing NU7026, a specific inhibitor of DNA-PK, with nilotinib or imatinib resulted in further sensitization to CLB but there was a greater sensitization to CLB with nilotinib than imatinib. These results suggest: (1) a more potent inhibition of c-abl is more efficacious in sensitizing CLL lymphocytes to CLB, (2) inhibition of c-abl results in a compensatory increase in DNA-PK and (3) inhibiting both DNA repair systems optimally sensitizes CLL lymphocytes to CLB, an effect which is most pronounced with the more potent c-abl inhibitor, nilotinib.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-100.

Phase II Multicenter Trial of Anthracycline Rechallenge With Pegylated Liposomal Doxorubicin Plus Cyclophosphamide for First-Line Therapy of Metastatic Breast Cancer Previously Treated With Adjuvant Anthracyclines

Purpose

Anthracyclines are a component of breast cancer chemotherapy regimens in both adjuvant and metastatic settings. Anthracycline rechallenge for metastatic disease, for those previously exposed to adjuvant anthracyclines, may not be considered because of concerns about efficacy, tolerability, and cumulative cardiotoxicity.

Patients and Methods

This prospective, multicenter, single-arm, phase II trial examined the efficacy and safety of pegylated liposomal doxorubicin (PLD) 35 mg/m2 plus cyclophosphamide 600 mg/m2 as first-line therapy, delivered every 3 weeks, in 70 patients who developed metastatic disease more than 12 months after completion of an adjuvant anthracycline-containing regimen. Seven patients discontinued treatment early and were excluded from the efficacy analysis.

Results

After a median of six cycles, the objective response rate was 38%. An additional 33% of patients achieved stable disease lasting more than 6 months, for an overall clinical benefit rate of 71%. The estimated median time to progression was 12.2 months. Median overall survival time was 16.5 months. Clinical response was equally robust in patients with and without prior taxane exposure. Treatment was well tolerated. The most common grade 3 to 4 toxicities were palmar-plantar erythrodysesthesia (PPE; 10%), dyspnea (9%), and neutropenia (9%). One (1.4%) of 70 patients discontinued treatment as a result of PPE. One patient (1.4%) experienced an infusion reaction requiring discontinuation. No symptomatic cardiac events were observed.

Conclusion

PLD plus cyclophosphamide is effective and well tolerated in patients with metastatic breast cancer who have received prior adjuvant anthracycline-containing chemotherapy. The majority of patients experienced a clinical benefit without any significant impact on cardiac function.