Long-term safety and anti-tumour activity of olaparib monotherapy after combination with carboplatin and paclitaxel in patients with advanced breast, ovarian or fallopian tube cancer

Attenuation of Tumor Burden in Response to Rucaparib in Lung Adenocarcinoma: The Contribution of Oxidative Stress, Apoptosis, and DNA Damage

In cancer, overactivation of poly (ADPribose) polymerases (PARP) plays a relevant role in DNA repair. We hypothesized that treatment with the PARP inhibitor rucaparib may reduce tumor burden via several biological mechanisms (apoptosis and oxidative stress) in mice. In lung tumors (LP07 lung adenocarcinoma) of mice treated/non-treated (control animals) with PARP inhibitor (rucaparib,150 mg/kg body weight/24 h for 20 day), PARP activity and expression, DNA damage, apoptotic nuclei, cell proliferation, and redox balance were measured using immunoblotting and immunohistochemistry. In lung tumors of rucaparib-treated mice compared to non-treated animals, tumor burden, PARP activity, and cell proliferation decreased, while DNA damage, TUNEL-positive nuclei, protein oxidation, and superoxide dismutase content (SOD)2 increased. In this experiment on lung adenocarcinoma, the pharmacological PARP inhibitor rucaparib elicited a significant improvement in tumor size, probably through a reduction in cell proliferation as a result of a rise in DNA damage and apoptosis. Oxidative stress and SOD2 also increased in response to treatment with rucaparib within the tumor cells of the treated mice. These results put the line forward to the contribution of PARP inhibitors to reduced tumor burden in lung adenocarcinoma. The potential implications of these findings should be tested in clinical settings of patients with lung tumors.

Combined inhibition of BADSer99 phosphorylation and PARP ablates models of recurrent ovarian carcinoma

Background

Poly (ADP-ribose) polymerase inhibitors (PARPis) have been approved for the treatment of recurrent epithelial ovarian cancer (EOC), regardless of BRCA status or homologous recombination repair deficiency. However, the low response of platinum-resistant EOC, the emergence of resistance in BRCA-deficient cancer, and therapy-associated toxicities in patients limit the clinical utility of PARPis in recurrent EOC.

Methods

The association of phosphorylated (p) BADS99 with clinicopathological parameters and survival outcomes in an EOC cohort was assessed by immunohistochemistry. The therapeutic synergy, and mechanisms thereof, between a pBADS99 inhibitor and PARPis in EOC was determined in vitro and in vivo using cell line and patient-derived models.

Results

A positive correlation between pBADS99 in EOC with higher disease stage and poorer survival is observed. Increased pBADS99 in EOC cells is significantly associated with BRCA-deficiency and decreased Cisplatin or Olaparib sensitivity. Pharmacological inhibition of pBADS99 synergizes with PARPis to enhance PARPi IC₅₀ and decreases survival, foci formation, and growth in ex vivo culture of EOC cells and patient-derived organoids (PDOs). Combined inhibition of pBADS99 and PARP in EOC cells or PDOs enhances DNA damage but impairs PARPi stimulated DNA repair with a consequent increase in apoptosis. Inhibition of BADS99 phosphorylation synergizes with Olaparib to suppress the xenograft growth of platinum-sensitive and resistant EOC. Combined pBADS99-PARP inhibition produces a complete response in a PDX derived from a patient with metastatic and chemoresistant EOC.

Conclusions

A rational and efficacious combination strategy involving combined inhibition of pBADS99 and PARP for the treatment of recurrent EOC is presented.

Ovarian cancer is difficult to successfully treat because it often recurs as the cancer becomes resistant to drugs used to treat it. As such, new drugs or combinations of drugs are needed to treat patients with recurrent ovarian cancer. Here, a drug combination is reported that is effective in experimental models of ovarian cancer, including those derived from patients. The combination approach uses drugs that have previously been approved for use in patients, known as PARP inhibitors, and another drug to inhibit cancer cell survival by targeting activation of a specific protein involved in cancer cell survival. The net effect of this drug combination in ovarian cancer models is greater than the sum of the drugs used individually. With further testing, this combination may offer a potential strategy to treat patients with recurrent ovarian cancer.

Zhang et al. test the therapeutic potential of an inhibitor of BAD phosphorylation, NPB, in epithelial ovarian cancer. The authors show that the small molecule synergises with PARP inhibition to kill patient-derived ovarian cancer organoids and suppress the growth of xenograft tumours, including a cisplatin-resistant model.

Combined PARP and Dual Topoisomerase Inhibition Potentiates Genome Instability and Cell Death in Ovarian Cancer

Although ovarian cancer is a rare disease, it constitutes the fifth leading cause of cancer death among women. It is of major importance to develop new therapeutic strategies to improve survival. Combining P8-D6, a novel dual topoisomerase inhibitor with exceptional anti-tumoral properties in ovarian cancer and compounds in preclinical research, and olaparib, a PARP inhibitor targeting DNA damage repair, is a promising approach. P8-D6 induces DNA damage that can be repaired by base excision repair or homologous recombination in which PARP plays a major role. This study analyzed benefits of combining P8-D6 and olaparib treatment in 2D and 3D cultures with ovarian cancer cells. Measurement of viability, cytotoxicity and caspase activity were used to assess therapy efficacy and to calculate the combination index (CI). Further DNA damage was quantified using the biomarkers RAD51 and γH2A.X. The combinational treatment led to an increased caspase activity and reduced viability. CI values partially show synergisms in combinations at 100 nM and 500 nM P8-D6. More DNA damage accumulated, and spheroids lost their membrane integrity due to the combinational treatment. While maintaining the same therapy efficacy as single-drug therapy, doses of P8-D6 and olaparib can be reduced in combinational treatments. Synergisms can be seen in some tested combinations. In summary, the combination therapy indicates benefits and acts synergistic at 100 nM and 500 nM P8-D6.

PARP Inhibitors for Breast Cancer: Germline BRCA1/2 and Beyond

Simple Summary

Poly-adenosine diphosphate ribose polymerase (PARP) inhibitors (PARPi) are effective against tumors with mutations in DNA repair genes, most commonly in the BRCA1 and BRCA2 genes. Because these tumors are unable to repair their DNA, PARPi have been used to target DNA repair pathways and are useful in the treatment of breast cancers with some of these alterations. There are two FDA-approved PARPi for patients with breast cancer—olaparib and talazoparib. The data on olaparib and talazoparib in the treatment of breast cancer are summarized in this review, and we also explore potential future applications of PARPi beyond inherited BRCA mutations.

Abstract

Poly-adenosine diphosphate ribose polymerase (PARP) inhibitors (PARPi) are approved for BRCA1/2 carriers with HER2-negative breast cancer in the adjuvant setting with a high risk of recurrence as well as the metastatic setting. However, the indications for PARPi are broader for patients with other cancer types (e.g., prostate and ovarian cancer), involving additional biomarkers (e.g., ATM, PALB2, and CHEK) and genomic instability scores. Herein, we summarize the data on PARPi and breast cancer and discuss their use beyond BRCA carriers.

Molecular methods for increasing the effectiveness of ovarian cancer treatment: a systematic review

Background: The aim of the current study is to analyze and summarize the latest research on improving therapy in ovarian cancer. Materials & methods: Data analysis was based on a review of publications from 2011 to 2021 in the PubMed database with use of the search terms including 'EGFR ovarian cancer', 'folate receptor inhibitors ovarian cancer', 'VEGF ovarian cancer', 'PDGF ovarian cancer' and 'CTLA-4 ovarian cancer'. Results: 6643 articles were found; 238 clinical trials and randomized control trials were analyzed; 122 studies were rejected due to inconsistency with the topic of the work. Conclusion: Extensive research on the treatment of ovarian cancer increases the chance of developing the most effective therapy suited to the individual needs of the patient.

Olaparib dose re-escalation in ovarian cancer patients who experienced severe and/or uncommon adverse events: A case series

AIM

Few real-world studies have reported detailed management and dose adjustment strategies of adverse events (AEs) of ovarian cancer (OC) patients treated with the poly(adenosine diphosphate-ribose) polymerase inhibitor olaparib. This case series aimed to describe olaparib AEs in Chinese OC patients in real-life settings and to explore dose modification strategies.

METHODS

We conducted a detailed examination of the clinical records of OC patients who were treated with olaparib at the Gynecologic Oncology Unit in Hong Kong from September 2015 to December 2019, including baseline characteristics, treatment outcomes, AEs, and management strategies, particularly dose modifications.

RESULTS

Nineteen patients were included, with a median olaparib treatment duration of 12 (range: 3-30) months. For recurrent platinum-sensitive cases (n = 16), the median progression-free survival was 16.0 months (95% confidence interval: 9.5-22.5). Eighteen (95%) patients experienced AE(s) of any grade, including four (21%) who experienced grade ≥3 AE(s). The most common AEs were as follows: nonhematologic fatigue (68%), nausea (42%), vomiting (26%), decreased appetite (26%), dyspepsia (21%), dizziness (21%), anemia (37%), neutropenia (26%), and thrombocytopenia (21%). Four specific cases involving anemia, lower limb lymphedema, myeloid neoplasm, and erythema nodosum are discussed separately. Eight patients required dose interruption or reduction due to AEs, of which five patients attempted and tolerated dose re-escalation.

CONCLUSION

In this study, most AEs were mild, but rare AEs were observed. In OC patients, olaparib AE management with dose reductions followed by re-escalations was feasible, including for anemia.

A Phase I dose-escalation study of two cycles carboplatin-olaparib followed by olaparib monotherapy in patients with advanced cancer

Preclinical studies have shown synergistic effects when combining PARP1/2 inhibitors and platinum drugs in BRCA1/2 mutated cancer cell models. After a formulation change of olaparib from capsules to tablets, we initiated a dose finding study of olaparib tablets bidaily (BID) continuously with carboplatin to prepare comparative studies in this patient group. Patients were included in a 3 + 3 dose‐escalation schedule: olaparib 25 mg BID and carboplatin area under the curve (AUC) 3 mg*min/mL d1/d22, olaparib 25 mg BID and carboplatin AUC 4 mg*min/mL d1/d22, followed by increasing dose‐levels of olaparib from 50 mg BID, 75 mg BID, to 100 mg BID with carboplatin at AUC 4 mg*min/mL d1/d22. After two cycles, patients continued olaparib 300 mg BID as monotherapy. Primary objective was to assess the maximum tolerable dose (MTD). Twenty‐four patients with a confirmed diagnosis of advanced cancer were included. Most common adverse events were nausea (46%), fatigue (33%) and platelet count decrease (33%). Dose‐level 3 (olaparib 75 mg BID and carboplatin AUC 4 mg*min/mL; n = 6) was defined as MTD. Fourteen out of 24 patients (56%) had a partial response as best response (RECIST 1.1). Systemic exposure of the olaparib tablet formulation appeared comparable to the previous capsule formulation with olaparib tablet AUC_0‐12 of 16.3 μg/mL*h at MTD. Polymers of ADP‐ribose levels in peripheral blood mononuclear cells were reduced by 98.7% ± 0.14% at Day 8 compared to Day 1 for dose‐level 3. Olaparib tablets 75 mg BID and carboplatin AUC 4 mg*min/mL for two cycles preceding olaparib monotherapy 300 mg is a feasible and tolerable treatment schedule for patients with advanced cancer.

What's new?

Preclinical studies have shown synergistic effects when combining PARP1/2‐inhibitors and platinum drugs in BRCA1/2 mutated cancer cell models. This phase I trial of olaparib tablets combined with carboplatin in advanced cancer patients showed that the combination has an acceptable side‐effect profile. The maximum tolerable dose was olaparib tablets 75 mg BID and carboplatin AUC 4 mg*min/ml. The observed preliminary anti‐tumor activity was encouraging, with 58% of patients having a decrease in tumor volume of more than 30%. This study shows that the tablet formulation of olaparib can be administered safely in combination with carboplatin, compared to the previous capsule formulation.

Olaparib for advanced breast cancer

Olaparib, an oral PARP-inhibitor, has shown clinical benefit for HER2-negative advanced breast cancer patients carrying a germinal BRCA1/2 mutation. In a randomized Phase III trial, olaparib significantly prolonged progression-free survival as compared with chemotherapy of physician choice. Moreover, in the same trial, a prespecified subgroup analysis reported an overall survival benefit for patients not previously pretreated with chemotherapy for metastatic disease. This review focuses on available preclinical, pharmacokinetic and pharmacodynamic data regarding olaparib and clinical evidence of its antitumor efficacy (both as monotherapy and in combination) and tolerability in breast cancer patients. Open questions, such as use of appropriate biomarkers for patient selection and combination/sequencing with other anticancer drugs, are also addressed.

Preclinical Studies Comparing Efficacy and Toxicity of DNA Repair Inhibitors, Olaparib, and AsiDNA, in the Treatment of Carboplatin-Resistant Tumors

Purpose: Carboplatin is used to treat many cancers, but occurrence of drug resistance and its high toxicity remain a clinical hurdle limiting its efficacy. We compared the efficacy and toxicity of DNA repair inhibitors olaparib or AsiDNA administered alone or in combination with carboplatin. Olaparib acts by inhibiting PARP-dependent repair pathways whereas AsiDNA inhibits double-strand break repair by preventing recruitment of enzymes involved in homologous recombination and non-homologous end joining. Experimental Design: Mice with MDA-MB-231 tumors were treated with carboplatin or/and olaparib or AsiDNA for three treatment cycles. Survival and tumor growth were monitored. Toxicities of treatments were assayed in C57BL/6 immunocompetent mice. Circulating blood hematocrits, bone marrow cells, and organs were analyzed 10 and 21 days after end of treatment using flow cytometry and microscopy analysis. Resistance occurrence was monitored after cycles of treatments with combination of AsiDNA and carboplatin in independent BC227 cell cultures. Results: Olaparib or AsiDNA monotherapies decreased tumor growth and increased mean survival of grafted animals. The combination with carboplatin further increased survival. Carboplatin toxicity resulted in a decrease of most blood cells, platelets, thymus, and spleen lymphocytes. Olaparib or AsiDNA monotherapies had no toxicity, and their combination with carboplatin did not increase toxicity in the bone marrow or thrombocytopenia. All animals receiving carboplatin combined with olaparib developed high liver toxicity with acute hepatitis at 21 days. In vitro, carboplatin resistance occurs after three cycles of treatment in all six tested cultures, whereas only one became resistant (1/5) after five cycles when carboplatin was associated to low doses of AsiDNA. All selected carboplatin-resistant clones retain sensitivity to AsiDNA. Conclusion: DNA repair inhibitor treatments are efficient in the platinum resistant model, MDA-MB-231. The combination with carboplatin improves survival. The association of carboplatin with olaparib is associated with high liver toxicity, which is not observed with AsiDNA. AsiDNA could delay resistance to carboplatin without increasing its toxicity.

Combined Strategies with Poly (ADP-Ribose) Polymerase (PARP) Inhibitors for the Treatment of Ovarian Cancer: A Literature Review

Poly (ADP-ribose) polymerase (PARP) inhibitors are the first clinically approved drugs designed to exploit synthetic lethality, and were first introduced as a cancer-targeting strategy in 2005. They have led to a major change in the treatment of advanced ovarian cancer, and altered the natural history of a disease with extreme genetic complexity and defective DNA repair via homologous recombination (HR) pathway. Furthermore, additional mechanisms apart from breast related cancer antigens 1 and 2 (BRCA1/2) mutations can also result in HR pathway alterations and consequently lead to a clinical benefit from PARP inhibitors. Novel combinations of PARP inhibitors with other anticancer therapies are challenging, and better understanding of PARP biology, DNA repair mechanisms, and PARP inhibitor mechanisms of action is crucial. It seems that PARP inhibitor and biologic agent combinations appear well tolerated and clinically effective in both BRCA-mutated and wild-type cancers. They target differing aberrant and exploitable pathways in ovarian cancer, and may induce greater DNA damage and HR deficiency. The input of immunotherapy in ovarian cancer is based on the observation that immunosuppressive microenvironments can affect tumour growth, metastasis, and even treatment resistance. Several biologic agents have been studied in combination with PARP inhibitors, including inhibitors of vascular endothelial growth factor (VEGF; bevacizumab, cediranib), and PD-1 or PD-L1 (durvalumab, pembrolizumab, nivolumab), anti-CTLA4 monoclonal antibodies (tremelimumab), mTOR-(vistusertib), AKT-(capivasertib), and PI3K inhibitors (buparlisib, alpelisib), as well as MEK 1/2, and WEE1 inhibitors (selumetinib and adavosertib, respectively). Olaparib and veliparib have also been combined with chemotherapy with the rationale of disrupting base excision repair via PARP inhibition. Olaparib has been investigated with carboplatin and paclitaxel, whereas veliparib has been tested additionally in combination with temozolomide vs. pegylated liposomal doxorubicin, as well as with oral cyclophosphamide, and topoisomerase inhibitors. However, overlapping myelosuppression observed with PARP inhibitor and chemotherapy combinations requires further investigation with dose escalation studies. In this review, we discuss multiple clinical trials that are underway examining the antitumor activity of such combination strategies.

PARP Inhibitors in the Treatment of Triple-Negative Breast Cancer

Breast cancer is a heterogeneous disease, manifesting in a broad differentiation in phenotypes and morphologic profiles, resulting in variable clinical behavior. Between 10 and 20% of all breast cancers are triple negative. Triple-negative breast cancer (TNBC) lacks the expression of human epidermal growth factor receptor 2 (HER2) and hormone receptors; therefore, to date, chemotherapy remains the backbone of treatment. TNBC tends to be aggressive and has a high histological grade, resulting in a poor 5-year prognosis. It has a high prevalence of BRCA1 mutations and an increased Ki-67 expression. This subtype usually responds well to taxanes and/or platinum compounds and poly (ADP-ribose) polymerase (PARP) inhibitors. Studies with PARP inhibitors have demonstrated promising results in the treatment of BRCA-mutated breast and ovarian cancer, and PARP inhibitors have been studied as monotherapy and in combination with cytotoxic therapy or radiotherapy. PARP inhibitor efficacy on poly (ADP-ribose) polymer (PAR) formation in vivo can be quantified by pharmacodynamic assays that measure PAR activity in peripheral blood mononuclear cells (PBMC). Biomarkers such as TP53, ATM, PALB2 and RAD51C might be prognostic or predictive indicators for treatment response, and could also provide targets for novel treatment strategies. In summary, this review provides an overview of the treatment options for basal-like TNBC, including PARP inhibitors, and focuses on the pharmacotherapeutic options in these patients.

What is the Current Effectiveness of Olaparib for Breast Cancer Patients with a BRCA Mutation? A Systematic Review

Background:

The Poly (ADP-ribose) polymerase inhibitor olaparib, acts against cancer cells in people with breast cancer pre-disposition gene mutations (BRCAm). Despite US and EU approval as a therapy for ovarian cancer patients with BRCAm, but research into olaparib therapy for breast cancer patients with BRCAm is in its infancy.

Objective:

As no systematic review has yet been undertaken to synthesise clinical trials looking at olaparib as a therapy for breast cancer patients with BRCAm, this systematic review aims to establish the current effectiveness of olaparib as a treatment for these patients.

Methods:

CINAHL, MEDLINE, Royal College of Nursing, Cochrane Library, Joanna Briggs Institute, Centre for Reviews and Dissemination, Internurse, Embase, Google Scholar and PubMed databases were searched, supplemented by a grey literature search, hand searching and cross-referencing. Authors independently reviewed and graded the studies also using Kmetet al. scoring system.

Results:

One long-term case study and six clinical trials were included. Heterogeneity prevented statistical meta-analysis, meaning only narrative synthesis was possible. The overall clinical benefit of olaparib appears to be greater and longer lived in BRCAm carriers compared to BRCAwt, and also when compared to standard chemotherapy treatments.

Conclusion:

Implications for nursing: nurses working in this field should be aware that the most compelling results were found in the subset of patients who harbour a BRCA mutation, meaning that olaparib should be regarded as a clinically effective potential therapy for these patients. Larger, longer-term trials including comparator arms are required to demonstrate benefits including overall survival, adverse effects and quality of life.

Precision oncology in the age of integrative genomics

Precision oncology applies genomic and other molecular analyses of tumor biopsies to improve the diagnosis and treatment of cancers. In addition to identifying therapeutic options, precision oncology tracks the response of a tumor to an intervention at the molecular level and detects drug resistance and the mechanisms by which it occurs. Integrative genomics can include sequencing specific panels of genes, exomes, or the entire triad of the patient's germline, tumor exome, and tumor transcriptome. Although the capabilities of sequencing technologies continue to improve, widespread adoption of genomics-driven precision oncology in the clinic has been held back by logistical, regulatory, financial, and ethical considerations. Nevertheless, integrative clinical sequencing programs applied at the point of care have the potential to improve the clinical management of cancer patients.

Olaparib tablets for the treatment of germ line BRCA-mutated metastatic breast cancer

INTRODUCTION

Germ line BRCA mutations (gBRCAm) are diagnosed in approximately 5% of unselected breast cancer patients. Olaparib is a new treatment option for patients with a gBRCAm who have metastatic HER2-negative breast cancer. Areas covered: Olaparib is an oral poly (ADP-ribose) polymerase inhibitor that has been shown in phase I-III clinical trials to have single-agent efficacy in breast cancer patients with gBRCAm. The recent phase III OlympiAD study demonstrated a statistically significant progression-free survival benefit compared with the chemotherapy control arm, although an overall survival benefit has not been demonstrated. The most common adverse events seen with olaparib include nausea, anemia, and vomiting. The most common grade 3 adverse events are anemia and neutropenia. Expert commentary: The US FDA-approved olaparib tablets in January 2018 for the treatment of patients with a gBRCAm and metastatic HER2-negative breast cancer. This is a well-tolerated and effective treatment option for this patient population, particularly in patients with triple-negative breast cancer in which chemotherapy is the only alternative. More data are needed to understand the role of olaparib in combination with endocrine therapy, other targeted agents, and chemotherapy, as well as sequentially with platinum chemotherapy in the metastatic setting.

Preliminary evaluation of a novel 18F-labeled PARP-1 ligand for PET imaging of PARP-1 expression in prostate cancer

INTRODUCTION

Poly (ADP-ribose) polymerase-1 (PARP-1) plays many roles in prostate cancer (PC), such as mediating DNA damage repair, transcriptional regulation and nuclear hormone receptor signaling. Because of this, PARP-1 has been targeted for therapy in PC, and non-invasive imaging of PARP-1 could help predict which patients are likely to respond to such therapy. Several PARP-1 positron emission tomography (PET) imaging agents have been developed and show promise for imaging PARP-1 expression in breast, brain, and lung cancer in small animals, but not as yet in prostate cancer. [¹⁸F]WC-DZ-F is an analogue of [¹⁸F]FluorThanatrace (FTT) and [¹²⁵I]KX1, which are well-established PARP-1 ligands for measuring PARP-1 expression. Herein, we evaluated the potential of [¹⁸F]WC-DZ-F for the imaging PARP-1 expression in PC.

METHODS

[¹⁸F]WC-DZ-F was synthesized by a two-step sequence. [¹⁸F]WC-DZ-F was evaluated by in vitro uptake studies in PC-3 cells and by in vivo biodistribution and microPET imaging using PC-3 tumor xenografts. Ex vivo autoradiography of PC-3 tumors after microPET imaging was also performed.

RESULTS

[¹⁸F]WC-DZ-F has high, PARP-1-specific uptake in PC-3 cells. In the microPET imaging study, [¹⁸F]WC-DZ-F accumulated in PC-3 xenograft tumors over 2 h, and the uptake was significantly reduced by blocking with olaparib. PC-3 tumors were clearly visualized in microPET images, and the imaging results were further confirmed by autoradiography of PC-3 tumors ex vivo. In the biodistribution study [¹⁸F]WC-DZ-F washed out quickly from most tissues within 2 h, except for the liver in which the uptake was not blockable by olaparib.

CONCLUSIONS

We synthesized a novel PARP-1 radioligand, [¹⁸F]WC-DZ-F. The preliminary evaluation of [¹⁸F]WC-DZ-F indicates that it is a suitable PET imaging agent for measuring PARP-1 expression in prostate cancer and should be applicable to other types of cancers.

Neoadjuvant Therapy for Breast Cancer: Established Concepts and Emerging Strategies

In the last decade, the systemic treatment approach for patients with early breast cancer has partly shifted from adjuvant treatment to neoadjuvant treatment. Systemic treatment administration started as a 'one size fits all' approach but is currently customized according to each breast cancer subtype. Systemic treatment in a neoadjuvant setting is at least as effective as in an adjuvant setting and has several additional advantages. First, it enables response monitoring and provides prognostic information; second, it downstages the tumor, allowing for less extensive surgery, improved cosmetic outcomes, and reduced postoperative complications such as lymphedema; and third, it enables early development of new treatment strategies by using pathological complete remission as a surrogate outcome of event-free and overall survival. In this review we give an overview of the current standard of neoadjuvant systemic treatment strategies for the three main subtypes of breast cancer: hormone receptor-positive, triple-negative, and human epidermal growth factor receptor 2-positive. Additionally, we summarize drugs that are under investigation for use in the neoadjuvant setting.

Emerging therapeutic modalities of PARP inhibitors in breast cancer

Inhibition of Poly (ADP-ribose) polymerase (PARP) has shown marked benefit for breast cancer with homologous recombination deficiency, whether driven by defects in BRCA1, BRCA2, or other pathway components. Since the initial approval of olaparib, a mostly investigated PARP inhibitor (PARPi), the clinical development of PARPi in breast cancer treatment has been a major emphasis. Researches in investigating platinum-PARPi combination use compared with platinum monotherapy demonstrated promising benefit in metastatic BRCA mutated breast cancer or TNBC, while no such superiority was observed in the neoadjuvant setting of TNBC. Moreover, the utility of PARP inhibition in BRCA1/2 mutated breast cancer with different platinum-free interval was investigated. There was a clear association between clinical benefit with PARPi and platinum sensitivity, whereas partial efficacy of PARPi still occurs in platinum-resistant patients. In addition, proof-of-principle studies of immunotherapy combined with PARPi in breast cancer have obtained promising results, indicating the potential benefit of the combination therapy in patients with breast cancer. These efforts, contributing to maximize the utility of PARPi, may drive a new era of this agent after its first routine use. In this review, we summarized the utility of combining platinum-PARPi in BRCA mutated breast cancer or TNBC compared with platinum monotherapy and provided promising prospects of PARPi as maintenance therapy in breast cancer, as well as providing a strong rationale for testing immunotherapy combined with PARPi in breast cancer to expand the clinical utility of PARPi.

The role of PARP inhibition in triple-negative breast cancer: Unraveling the wide spectrum of synthetic lethality

Triple-negative breast cancer (TNBC) accounts for approximately 15-20% of all breast cancers and is characterized by a lack of immunohistochemical expression of estrogen receptors (ER), progesterone receptors (PR) and HER2. TNBC is associated with poor long-term outcomes compared with other breast cancer subtypes. Many of these tumors are also basal-like cancers which are characterized by an aggressive biological behavior with a distant recurrence peak observed early at 3 years following diagnosis. Furthermore, metastatic TNBC bears a dismal prognosis with an average survival of 12 months. Although the prevalence of genetic alterations among women with TNBC differs significantly by ethnicity, race and age, BRCA mutations (including both germline mutations and somatic genetic aberrations) are found in up to 20-25% of unselected patients and especially in those of the basal-like immunophenotype. Therefore, defects in the DNA repair pathway could represent a promising therapeutic target for this subgroup of TNBC patients. Poly(ADP-ribose) polymerase (PARP) inhibitors exploit this deficiency through synthetic lethality and have emerged as promising anticancer therapies, especially in BRCA1 or BRCA2 mutation carriers. Several PARP inhibitors are currently being evaluated in the adjuvant, neo-adjuvant, and metastatic setting for the treatment of breast cancer patients with a deficient homologous recombination pathway. In this article, we review the major molecular characteristics of TNBC, the mechanisms of homologous recombination, and the role of PARP inhibition as an emerging therapeutic strategy.

Olaparib for the treatment of breast cancer

INTRODUCTION

Mutations in BRCA1 and BRCA2 genes account for around 2-3% of breast cancer events and more than 10% of triple negative breast cancers. Olaparib (Lynparza®), an orally administered PARP inhibitor, demonstrated clinical benefit in a phase III trial for mutated BRCA-positive HER2 negative metastatic breast cancer. Areas covered: This review gives an overview of available preclinical and clinical data regarding olaparib, including its chemistry, mechanism of action, pharmacokinetics and pharmacodynamics, and evidence supporting antitumor efficacy and safety profile in breast cancer patients. Expert commentary: Olaparib improves progression-free survival in germline BRCA mutated HER2 negative metastatic breast cancer patients as compared to standard chemotherapy, with a manageable toxicity profile. Efficacy is of clinical relevance especially in the context of triple negative breast cancer. However, several aspects, such as sequencing or combination of these agents with other anticancer agents and identification of appropriate biomarkers, still need to be clearly defined.

The effect of food on the pharmacokinetics of niraparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, in patients with recurrent ovarian cancer

PURPOSE

Niraparib is a highly selective inhibitor of PARP-1 and PARP-2 approved in the United States for maintenance treatment of adult patients with recurrent ovarian cancer in complete or partial response to platinum-based chemotherapy. In this open-label crossover study, we evaluated the effects of food on niraparib pharmacokinetics (PK) and safety.

METHODS

Patients received a single 300-mg dose of niraparib either after a high-fat meal or under fasting conditions. After a 7-day PK assessment, all patients received a second 300-mg dose of niraparib under the opposite condition, followed by 7-day PK assessment. Blood samples for PK analyses were collected at baseline (on days 1 and 8) and up to 168 h post-dose. Bioequivalence between conditions was defined by the 90% confidence intervals (CIs) for area under the plasma concentration-time curve (AUC) from 0 to last measurable concentration (AUC_0-last) and from 0 to infinity (AUC_0-∞) being within the 80-125% range.

RESULTS

The high-fat meal/fasting ratios of geometric least-squares means for AUC_0-last and AUC_0-∞ were 106.8 (90% CI 97.8-116.6) and 110.1 (90% CI 99.7-121.6), respectively, indicating bioequivalence between conditions. Mean half-life, maximum plasma concentration (C_max), and time to C_max after the high-fat meal were similar to, 27% smaller than, and 128% greater than after fasting, respectively. Adverse events were similar between conditions.

CONCLUSIONS

A high-fat meal did not impact the PK profile of niraparib, indicating that niraparib can be taken with or without food. Niraparib was safe and well-tolerated.

Parent-Metabolite Pharmacokinetic Modeling and Pharmacodynamics of Veliparib (ABT-888), a PARP Inhibitor, in Patients With BRCA 1/2-Mutated Cancer or PARP-Sensitive Tumor Types

Veliparib (ABT-888) is a novel oral poly-ADP-ribose polymerase (PARP) inhibitor that is being developed for the treatment of hematologic malignancies and solid tumors. Although the pharmacokinetics of veliparib have been studied in combination with cytotoxic agents, limited information exists regarding the pharmacokinetics (PK) of chronically dosed single-agent veliparib in patients with either BRCA 1/2-mutated cancer or PARP-sensitive tumors. The objectives of the current analysis were to characterize the population pharmacokinetics of veliparib and its primary, active metabolite, M8, and to evaluate the relationship between veliparib and M8 concentrations and poly-ADP-ribose (PAR) level observed in peripheral blood mononuclear cells (PBMCs). Seventy-one subjects contributed with veliparib plasma concentrations, M8 plasma concentrations, and PAR levels in PBMCs. Veliparib and M8 concentrations were modeled simultaneously using a population PK approach. A 2-compartment model with delayed first-order absorption and the elimination parameterized as renal (CLR /F) and nonrenal clearance (CLNR /F) adequately described veliparib pharmacokinetics. The pharmacokinetics of the M8 metabolite was described with a 2-compartment model. Creatinine clearance(CLCR ) and lean body mass (LBM) were identified as significant predictors of veliparib CLR /F and central volume of distribution, respectively. For a typical subject (LBM, 48 kg; CLCR , 95 mL/min), total clearance (CLR /F + CLNR /F), and central and peripheral volume of distribution for veliparib were estimated as 17.3 L/h, 98.7 L, and 48.3 L, respectively. At least 50% inhibition of PAR levels in PBMCs was observed at dose levels ranging from 50 to 500 mg.

Population pharmacokinetic analyses of the effect of carboplatin pretreatment on olaparib in recurrent or refractory women's cancers

PURPOSE

Combining olaparib with carboplatin was recently shown to be active in both BRCA and non-BRCA mutant cancers in a recent phase I/Ib combination trial. The optimal drug sequence recommended was carboplatin 1-day before olaparib. However, carboplatin pre-treatment induced a ~50% faster olaparib clearance.

METHODS

To further explore this drug interaction, a population pharmacokinetic (PK) model was designed that included a lag time parameter, a second absorption compartment from tablet formulation, a single distribution/elimination compartment, and covariance among the clearance and volume parameters.

RESULTS

Clearance (6.8 L/h) and volume (33 L) estimates were comparable with literature. The only significant covariate was the presence of carboplatin on olaparib clearance, consistent with published noncompartmental PK and in vitro data.

CONCLUSIONS

Simulations predicted lower steady-state peak/trough olaparib exposure through 24-36 h post carboplatin pre-treatment, but this effect was lost by day 2 and thus no dose adjustment is recommended.

Nanoformulation of Olaparib Amplifies PARP Inhibition and Sensitizes PTEN/TP53-Deficient Prostate Cancer to Radiation

The use of PARP inhibitors in combination with radiotherapy is a promising strategy to locally enhance DNA damage in tumors. Here we show that radiation-resistant cells and tumors derived from a Pten/Trp53-deficient mouse model of advanced prostate cancer are rendered radiation sensitive following treatment with NanoOlaparib, a lipid-based injectable nanoformulation of olaparib. This enhancement in radiosensitivity is accompanied by radiation dose-dependent changes in γ-H2AX expression and is specific to NanoOlaparib alone. In animals, twice-weekly intravenous administration of NanoOlaparib results in significant tumor growth inhibition, whereas previous studies of oral olaparib as monotherapy have shown no therapeutic efficacy. When NanoOlaparib is administered prior to radiation, a single dose of radiation is sufficient to triple the median mouse survival time compared to radiation only controls. Half of mice treated with NanoOlaparib + radiation achieved a complete response over the 13-week study duration. Using ferumoxytol as a surrogate nanoparticle, MRI studies revealed that NanoOlaparib enhances the intratumoral accumulation of systemically administered nanoparticles. NanoOlaparib-treated tumors showed up to 19-fold higher nanoparticle accumulation compared to untreated and radiation-only controls, suggesting that the in vivo efficacy of NanoOlaparib may be potentiated by its ability to enhance its own accumulation. Together, these data suggest that NanoOlaparib may be a promising new strategy for enhancing the radiosensitivity of radiation-resistant tumors lacking BRCA mutations, such as those with PTEN and TP53 deletions. Mol Cancer Ther; 16(7); 1279-89. ©2017 AACR.

Therapeutic targeting and patient selection for cancers with homologous recombination defects

INTRODUCTION

DNA double-strand breaks (DSBs) are toxic DNA lesions that can be repaired by non-homologous end-joining (NHEJ) or homologous recombination (HR). Mutations in HR genes elicit a predisposition to cancer; yet, they also result in increased sensitivity to certain DNA damaging agents and poly (ADP-ribose) polymerase (PARP) inhibitors. To optimally implement PARP inhibitor treatment, it is important that patients with HR-deficient tumors are adequately selected. Areas covered: Herein, the authors describe the HR pathway mechanistically and review the treatment of HR-deficient cancers, with a specific focus on PARP inhibition for BRCA1/2-mutated breast and ovarian cancer. In addition, mechanisms of acquired PARP inhibitor resistance are discussed. Furthermore, combination therapies with PARP inhibitors are reviewed, in the context of both HR-deficient and HR-proficient tumors and methods for proper patient selection are also discussed. Expert opinion: Currently, only patients with germline or somatic BRCA1/2 mutations are eligible for PARP inhibitor treatment and only a proportion of patients respond. Patients with HR-deficient tumors caused by other (epi)genetic events may also benefit from PARP inhibitor treatment. Ideally, selection of eligible patients for PARP inhibitor treatment include a functional HR read-out, in which cancer cells are interrogated for their ability to perform HR repair and maintain replication fork stability.

Preclinical studies for the combination of paclitaxel and curcumin in cancer therapy (Review)

Cancer is one of the most common causes of death and remains the first in China and the second in the US. The common treatments for cancer include surgery, radiation, chemotherapy, targeted therapy and immunotherapy, while chemotherapy remains one of the most important treatments. However, the efficacy of chemotherapy is limited due to drug induced-toxicities and resistance, particularly multiple drug resistance (MDR). Therefore, discovery and development of novel therapeutic drugs and/or combination therapy are urgently needed to reduce toxicity and improve efficacy. Paclitaxel has been widely used to treat various cancers including cervical, breast, ovarian, brain, bladder, prostate, liver and lung cancers. However, its therapeutic efficacy is limited and MDR is a major obstacle. Recently, numerous preclinical studies have shown that the combination of paclitaxel and curcumin may be an ideal strategy to reverse MDR and synergistically improve their therapeutic efficacy in cancer therapy. This review mainly focuses on the current development and progress of the combination of paclitaxel and curcumin in cancer therapy preclinically.

New Developments in Breast Cancer and Their Impact on Daily Practice in Pathology

Advances in research have transformed our understanding of breast cancers and have altered the daily practice of pathology. Theranostic evaluations performed by pathologists are now critical in triaging the patients into appropriate treatment groups, as are new guidelines that were recently established for the evaluation of HER2/neu gene amplification. Emerging molecular classifications of breast cancers bring novel perspectives to the assessment of individual cases, and opportunities for better treatments. Molecular studies have particularly shed light on distinct biological subsets of triple-negative breast cancers, for which new targeted therapies are being developed. The prognostic and therapeutic utility of new histopathologic parameters, such as tumor-infiltrating lymphocytes, are also being elucidated, and new protocols have been devised for the pathologic evaluation of breast specimens that have undergone neoadjuvant treatment. Novel clinical practices, such as radioactive seed localization, also affect the way breast specimens are processed and evaluated. In this brief review, we highlight the developments that are most relevant to pathology and are changing or could potentially impact our daily practice.

PARP inhibitor combination therapy

In 2014, olaparib (Lynparza) became the first PARP (Poly(ADP-ribose) polymerase) inhibitor to be approved for the treatment of cancer. When used as single agents, PARP inhibitors can selectively target tumour cells with BRCA1 or BRCA2 tumour suppressor gene mutations through synthetic lethality. However, PARP inhibition also shows considerable promise when used together with other therapeutic agents. Here, we summarise both the pre-clinical and clinical evidence for the utility of such combinations and discuss the future prospects and challenges for PARP inhibitor combinatorial therapies.

Cytotoxic and targeted therapy for hereditary cancers

There is a number of drugs demonstrating specific activity towards hereditary cancers. For example, tumors in BRCA1/2 mutation carriers usually arise via somatic inactivation of the remaining BRCA allele, which makes them particularly sensitive to platinum-based drugs, PARP inhibitors (PARPi), mitomycin C, liposomal doxorubicin, etc. There are several molecular assays for BRCA-ness, which permit to reveal BRCA-like phenocopies among sporadic tumors and thus extend clinical indications for the use of BRCA-specific therapies. Retrospective data on high-dose chemotherapy deserve consideration given some unexpected instances of cure from metastatic disease among BRCA1/2-mutated patients. Hereditary non-polyposis colorectal cancer (HNPCC) is characterized by high-level microsatellite instability (MSI-H), increased antigenicity and elevated expression of immunosuppressive molecules. Recent clinical trial demonstrated tumor responses in HNPCC patients treated by the immune checkpoint inhibitor pembrolizumab. There are successful clinical trials on the use of novel targeted agents for the treatment or rare cancer syndromes, e.g. RET inhibitors for hereditary medullary thyroid cancer, mTOR inhibitors for tumors arising in patients with tuberous sclerosis (TSC), and SMO inhibitors for basal-cell nevus syndrome. Germ-line mutation tests will be increasingly used in the future for the choice of the optimal therapy, therefore turnaround time for these laboratory procedures needs to be significantly reduced to ensure proper treatment planning.

Dimethylfumarate inhibits melanoma cell proliferation via p21 and p53 induction and bcl-2 and cyclin B1 downregulation

Recent evidence suggests that dimethylfumarate (DMF), known as a highly potent anti-psoriatic agent, might have anti-tumorigenic properties in melanoma. It has recently been demonstrated that DMF inhibits melanoma proliferation by apoptosis and cell cycle inhibition and therefore inhibits melanoma metastasis. Nonetheless, the underlying mechanisms remain to be evaluated. To elucidate the effects of DMF on melanoma cell lines (A375, SK-Mel), we first performed cytotoxicity assays. No significant lactatedehydogenase (LDH) release could be found. In further analysis, we showed that DMF suppresses melanoma cell proliferation in a concentration-dependent manner. To examine whether these effects are conveyed by apoptotic mechanisms, we studied the amount of apoptotic nucleosomes and caspase 3/7 activity using ELISA analysis. Significant apoptosis was induced by DMF in both cell lines, and this could be paralleled with bcl-2 downregulation and PARP-1 cleavage. We also performed cell cycle analysis and found that DMF induced concentration-dependent arrests of G0/G1 as well as G2/M. To examine the underlying mechanisms of cell cycle arrest, we analyzed the expression profiles of important cell cycle regulator proteins such as p53, p21, cyclins A, B1, and D1, and CDKs 3, 4, and 6. Interestingly, DMF induced p53 and p21 yet inhibited cyclin B1 expression in a concentration-dependent manner. Other cell cycle regulators were not influenced by DMF. The knockdown of DMF induced p53 via siRNA led to significantly reduced apoptosis but had no influence on cell cycle arrest. We examined the adhesion of melanoma cells on lymphendothelial cells during DMF treatment and found a significant reduction in interaction. These data provide evidence that DMF inhibits melanoma proliferation by reinduction of important cell cycle inhibitors leading to a concentration-dependent G0/G1 or G2/M cell cycle arrest and induction of apoptosis via downregulation of bcl-2 and induction of p53 and PARP-1 cleavage. Hence, DMF might be an interesting agent in the treatment of melanoma and is worth further investigation in vivo.

PARP inhibition and gynecologic malignancies: A review of current literature and on-going trials

The poly (ADP-ribose) polymerase (PARP) family of enzymes is important in several DNA repair pathways. Drugs that inhibit these enzymes have been investigated in many types of cancer, but their application in the treatment of gynecologic malignancies has rapidly evolved - as manifested by the 2014 FDA approval for olaparib in the treatment of recurrent ovarian cancer associated with a germline BRCA mutation (gBRCA). In efforts to broaden their efficacy, current clinical trials have demonstrated benefit of olaparib, and other PARP inhibitors (PARPi), as single agents and in combination with cytotoxic chemotherapy and biologic agents, in wide ranging populations. Although the majority of data for PARPi in gynecologic malignancies has been specifically regarding ovarian cancer, their role in the treatment of uterine and cervical cancer is currently being investigated. This review will serve as a synopsis of seminal trials to date, summarize the breadth of clinical application in on-going studies, query how these results may change future practice, and reflect on questions yet to be answered.

A phase I followed by a randomized phase II trial of two cycles carboplatin-olaparib followed by olaparib monotherapy versus capecitabine in BRCA1- or BRCA2-mutated HER2-negative advanced breast cancer as first line treatment (REVIVAL): study protocol for a randomized controlled trial

Background

Preclinical studies in breast cancer models showed that BRCA1 or BRCA2 deficient cell lines, when compared to BRCA proficient cell lines, are extremely sensitive to PARP1 inhibition. When combining the PARP1 inhibitor olaparib with cisplatin in a BRCA1-mutated breast cancer mouse model, the combination induced a larger response than either of the two compounds alone. Several clinical studies have investigated single agent therapy or combinations of both drugs, but no randomized clinical evidence exists for the superiority of carboplatin-olaparib versus standard of care therapy in patients with BRCA1- or BRCA2--mutated metastatic breast cancer.

Methods/design

This investigator-initiated study contains two parts. Part 1 is a traditional 3 + 3 dose escalation study of the carboplatin-olaparib combination followed by olaparib monotherapy. The carboplatin dose will be escalated from area under the curve (AUC) 3 to AUC 4 with an olaparib dose of 25 mg BID. Olaparib is subsequently escalated to 50, 75, and 100 mg BID until >1/6 of patients develop dose-limiting toxicity (DLT). The dose level below will be the maximum tolerable dose (MTD). It is expected that 15–20 patients are needed in Part I.

In Part 2 BRCA1- or BRCA2-mutated HER2-negative breast cancer patients will be randomized between standard capecitabine 1250 mg/m² BID day 1–14 q day 22, versus 2 cycles carboplatin-olaparib followed by olaparib monotherapy 300 mg BID. In total 104 events in 110 patients need to be observed to detect a 75 % clinically meaningful improvement in progression-free survival (PFS), from a median of 4 months (control) to 7 months (experimental) assuming a 2-year accrual and ≥6 months of follow-up with 80 % power (5 %, two-sided significance level). After progression on first line treatment, patients will receive physician’s best choice of paclitaxel, vinorelbine, eribulin, or capecitabine (experimental arm only) at standard dose. A compassionate use program of olaparib is available for patients in the standard arm after progression on second line treatment.

Discussion

Results might be pivotal for registration of olaparib as standard first line treatment in advanced BRCA1- or BRCA2-mutated breast cancer.

Trial registration

ClinicalTrials.gov identifier: NCT02418624. Registered on 9 March 2015. EudraCT number: 2013-005590-41. Registered on 15 October 2014. Protocol version 3.0.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1423-0) contains supplementary material, which is available to authorized users.

Emerging therapeutic targets in metastatic progression: A focus on breast cancer

Metastasis is the underlying cause of death for the majority of breast cancer patients. Despite significant advances in recent years in basic research and clinical development, therapies that specifically target metastatic breast cancer remain inadequate, and represents the single greatest obstacle to reducing mortality of late-stage breast cancer. Recent efforts have leveraged genomic analysis of breast cancer and molecular dissection of tumor-stromal cross-talk to uncover a number of promising candidates for targeted treatment of metastatic breast cancer. Rational combinations of therapeutic agents targeting tumor-intrinsic properties and microenvironmental components provide a promising strategy to develop precision treatments with higher specificity and less toxicity. In this review, we discuss the emerging therapeutic targets in breast cancer metastasis, from tumor-intrinsic pathways to those that involve the host tissue components, including the immune system.

Profile of olaparib in the treatment of advanced ovarian cancer

Olaparib is a poly(ADP-ribose) polymerase inhibitor that received accelerated approval from the US Food and Drug Administration as monotherapy for patients with germline BRCA mutations and ovarian cancer treated with three or more prior lines of chemotherapy. This article summarizes the mechanism of poly(ADP-ribose) polymerase inhibition, therapeutic profile and uses of olaparib, and current and ongoing literature pertaining to olaparib in advanced ovarian cancer.

Novel Water-Borne Polyurethane Nanomicelles for Cancer Chemotherapy: Higher Efficiency of Folate Receptors Than TRAIL Receptors in a Cancerous Balb/C Mouse Model

PURPOSE

Since the introduction of nanocarriers, the delivery of chemotherapeutic agents for treatment of patients with cancer has been possible with better effectiveness. The latest findings are also support that further enhancement in therapeutic effectiveness of these nanocarriers can be attained, if surface decoration with proper targeting agents is considered.

METHODS

This study aimed at treating a variety of 4T1 murine breast cancer cell line, mainly demonstrating high folate and TRAIL receptor expression of cancerous cells. The therapeutic efficacy of paclitaxel loaded Cremophore EL (Taxol®), paclitaxel loaded waterborne polyurethane nanomicelles (PTX-PU) and paclitaxel loaded waterborne polyurethane nanomicelles conjugated with folate (PTX-PU-FA) and TRAIL (PTX-PU-TRAIL) on treating 4T1 cell was also compared.

RESULTS

The findings that worth noting are: PTX-PU outperformed Taxol® in a Balb/C mouse model, furthermore, tumor growth was adequately curbed by folate and TRAIL-decorated nanomicelles rather than the unconjugated formulation. Tumors of mice treated with PTX-PU-FA and PTX-PU-TRAIL shrank substantially compared to those treated with Taxol®, PTX-PU and PTX-PU-TRAIL (average 573 mm(3) versus 2640, 846, 717 mm(3) respectively), 45 days subsequent to tumor inoculation. The microscopic study of hematoxylin-eosin stained tumors tissue and apoptotic cell fraction substantiated that the most successful therapeutic effects have been observed for the mice treated with PTX-PU-FA (about 90% in PTX-PU-FA versus 75%, 60%, 15% in PTX-PU-TRAIL, PTX-PU, and Taxol® group respectively).

CONCLUSIONS

Using folate-targeted nanocarriers to treat cancers characterized by a high level of folate ligand expression is well substantiated by the findings of this study.

Reduced tumor burden through increased oxidative stress in lung adenocarcinoma cells of PARP-1 and PARP-2 knockout mice

Lung cancer (LC) is currently a major leading cause of cancer deaths worldwide. Poly(ADP-ribose) polymerases (PARP)-1 and -2 play important roles in DNA repair and other cell functions. Oxidative stress triggers autophagy and apoptosis. PARP inhibitors are currently used as anticancer strategies including LC. We hypothesized that inhibition of either PARP-1 or -2 expressions in the host animals influences tumor burden through several biological mechanisms, mainly redox imbalance (enhanced oxidative stress and/or decreased antioxidants, and cell regulators) in wild type (WT) lung adenocarcinoma cells. Compared to WT control tumors, in those of Parp-1(-/-) and Parp-2(-/-) mice: 1) tumor burden, as measured by weight, and cell proliferation rates were decreased, 2) oxidative stress levels were greater, whereas those of the major antioxidant enzymes were lower especially catalase, 3) tumor apoptosis and autophagy levels were significantly increased, and 4) miR-223 and nuclear factor of activated T-cells (NFAT)c-2 expression was decreased (the latter only in Parp-1(-/-) mice). Furthermore, whole body weight gain at the end of the study period also improved in Parp-1(-/-) and Parp-2(-/-) mice compared to WT animals. We conclude that PARP-1 and -2 genetic deletions in the host mice induced a significant reduction in tumor burden most likely through alterations in redox balance (downregulation of antioxidants, NFATc-2 and miR223, and increased oxidative stress), which in turn led to increased apoptosis and autophagy. Furthermore, tumor progression was also reduced probably as a result of cell cycle arrest induced by PARP-1 and -2 inhibition in the host mice. These results highlight the relevance of the host status in tumor biology, at least in this experimental model of lung adenocarcinoma in mice. Future research will shed light on the effects of selective pharmacological inhibitors of PARP-1 and PARP-1 in the host and tumor burden, which could eventually be applied in actual clinical settings.