Is liquid biopsy useful in patients with GI malignancies and exclusive peritoneal disease?

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Background: Peritoneal carcinomatosis (PC) is a common manifestation in gastro-intestinal (GI) cancers.10-20 % of patients (pts) will present isolated, unresectable peritoneal disease with poor prognosis. In the past years, circulating tumor DNA (ctDNA) has emerged as a novel and less invasive biomarker for molecular diagnosis and disease monitoring. We aimed to evaluate the ability of PC to shed ctDNA into circulation in a cohort of pts with GI cancers and isolated PC treated in our institution. Methods: We reviewed retrospectively the results of liquid biopsies obtained at progression or at diagnosis. Genomic analysis was done using Foundation One liquid CDx panel. Data on demographics, tumor type, clinical outcomes and molecular alterations (MA) have been collected. Results: Out of 400 GI pts tested, 85 with exclusively PC were included in the analysis. The main characteristics were as follows: 45(53%) female, median age of 57 years (IQR: 24-79), majority have received systemic chemotherapy (all were progressive) (n=63, 74%) with median number of previous lines 1 (range: 0-3). Most common tumor types were as follows: gastric (n=24, 28%), colorectal (n=22, 26%) and primary peritoneal (n=20, 24%) cancers. The median index of peritoneal carcinomatosis was 23(IQR: 6-39). The tumor fraction was very low or undetectable in a proportion of 81% (n=69), median Tumor Mutational Burden was 1 mutation per megabase and was not correlated to tumor volume. Gene alterations were found in a proportion of 56% of pts (n=48) but most common alteration were TP 53 (n=22 pts, 26%) and KRAS mutation (n=14 pts, 16%). Targetable MA were identified only in 11 pts (13%) as follows: ATM, ARID1A, BRAFV600E, ERBB2, krasG12C. Three of them were included in a clinical trial. Germline mutations were found in 5 pts: ATM, CDH1, BRCA2, MSH6, BAP1. For colorectal pts known KRAS and BRAF V600E mutations were confirmed in plasma in a proportion of 32% (7 pts out of 22), for pancreatic cancer the KRAS in 17% (3 out of 18) and for gastric cancer, ERBB2 amplification in 5% (1 out of 22 pts). In pts with primary peritoneal disease: pseudomyxoma and mesothelioma, one patient harbored a known germline BAP 1 and kras G12C mutation without other targetable MA. The median survival in MA group was higher compared to non-MA. Conclusions: Isolated Pc and primary peritoneal cancers have distinct clinical and biological characteristics. The clinical utility of ctDNA seems to be limited in isolated PC or primary peritoneal cancers. However, it is not very clear if this to tumor location or to the ability of peritoneum to seed ctDNA.

Efficacy of trastuzumab emtansine (T-DM1) and lapatinib after dual HER2 inhibition with trastuzumab and pertuzumab in patient with metastatic breast cancer: Retrospective data from a French multicenter real-life cohort

Purpose

Trastuzumab-emtansine (T-DM1), as well as lapatinib plus capecitabine were proven effective in two Phase III studies, following first-line trastuzumab plus a taxane. The introduction of dual HER2 blockade by trastuzumab and pertuzumab as first-line has positioned T-DM1 into second-line, and lapatinib plus capecitabine beyond, without formal evaluation of these strategies.

Methods

ESME Data Platform (NCT03275311) included individual data from all patients aged ≥18 years, in whom first-line treatment for metastatic breast cancer (MBC) was initiated between January 1, 2008 and December 31, 2016 in one of the 18 French Comprehensive Cancer Centers. The efficacy of T-DM1 and lapatinib plus capecitabine combination, following double blockade associating trastuzumab and pertuzumab were evaluated in this national real-life database. Eligibility criteria were: female, MBC, HER2+ tumor, first-line taxane-based chemotherapy and dual HER2-blockage by trastuzumab plus pertuzumab. Cohort A received second-line T-DM1, and Cohort B second-line T-DM1 and third or fourth-line lapatinib plus capecitabine.

Results

Cohort A comprised 233 patients, and Cohort B 47 patients. Median progression-free survival (PFS) was 7.1 months in Cohort A and 4.6 months in Cohort B. Median overall survival were 36.7 months and 12.9 months, respectively. PFS was significantly dependent on the preceding treatment line's duration. In cohort A, HER2 expression status was a significant predictive factor of PFS.

Conclusion

First-line trastuzumab plus pertuzumab do not markedly diminish T-DM1's efficacy in second-line. Similarly, sequential treatment with trastuzumab plus pertuzumab then T-DM1 does not noticeably modify the efficacy of lapatinib plus capecitabine.

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French real-life cohort.

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Dual blockade HER2 does not markedly diminish T-DM1's activity in second-line and lapatinib's activity in third or fourth line.

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The second-line (T-DM1) PFS was significantly longer when the first-line treatment with trastuzumab plus pertuzumab was ≥12 months.

Genome erosion and evidence for an intracellular niche - exploring the biology of mycoplasmas in Atlantic salmon

Mycoplasmas are the smallest autonomously self-replicating life form on the planet. Members of this bacterial genus are known to parasitise a wide array of metazoans including vertebrates. Whilst much research has been significant targeted at parasitic mammalian mycoplasmas, very little is known about their role in other vertebrates. In the current study, we aim to explore the biology of mycoplasmas in Atlantic Salmon, a species of major significance for aquaculture, including cellular niche, genome size structure and gene content. Using fluorescent in-situ hybridisation (FISH), mycoplasmas were targeted in epithelial tissues across the digestive tract (stomach, pyloric caecum and midgut) from different development stages (eggs, parr, subadult) of farmed Atlantic salmon (Salmo salar), and we present evidence for an intracellular niche for some of the microbes visualised. Via shotgun metagenomic sequencing, a nearly complete, albeit small, genome (~0.57 MB) as assembled from a farmed Atlantic salmon subadult. Phylogenetic analysis of the recovered genome revealed taxonomic proximity to other salmon derived mycoplasmas, as well as to the human pathogen Mycoplasma penetrans (~1.36 Mb). We annotated coding sequences and identified riboflavin pathway encoding genes and sugar transporters, the former potentially consistent with micronutrient provisioning in salmonid development. Our study provides insights into mucosal adherence, the cellular niche and gene catalog of Mycoplasma in the gut ecosystem of the Atlantic salmon, suggesting a high dependency of this minimalist bacterium on its host. Further study is required to explore and functional role of Mycoplasma in the nutrition and development of its salmonid host.

NCOG-19. BEVACIZUMAB IN REAL LIFE PATIENTS WITH RECURRENT GLIOBLASTOMA: BENEFIT OR FUTILITY?

Angiogenesis represents a hallmark of glioblastoma but most trials disappointed and failed to change the poor outcome of this disease. However, Bevacizumab (Bev) is widely used in clinical practice by expert oncologists due to experience or efficacy in real life.We retrospectively reviewed the use of Bev and its benefit in terms of Time to treatment failure (TTF), Overall Survival(OS), Objective Response Rate (ORR) and clinical benefit. METHODS: We analyzed two hundred and two patients treated at Gustave Roussy Cancer Campus with Bev until definitive failure for recurrent glioblastoma between 2006 and 2016. Patients were treated with Bev alone or in association with radiotherapy, temozolomide, lomustine or irinotecan. RESULTS: The median duration of Bev treatment until definitive failure was 6 months. The median TTF was 7.27 months(95%CI 6.30-8.24) and the median OS from diagnosis was 22.43 months(95%CI 19.68-25.18). Two patients were still alive without active treatment at the end of study. A hundred and fourteen (56%) patients experienced symptom amelioration and seventy-five (37%) improved their Performance Status. Fifty percent of patients exhibited Partial and Complete Response on MRI, as best radiological response, within 1.6 months. No patient had anaphylactic reaction. Grade 1-2 hypertension(HT)(17%) and grade 1(10%) proteinuria were most common. Six patients presented lethal toxicity: 4 with GI perforation, 1 p with cerebral hemorrhage and 1 p with arterial bleeding. HT was correlated with treatment response in 67% of patients. A neutrophil count superior to 6000/mm³ was associated with longer TTF(mTTF 8.23m(95%CI 6.64-9.82). CONCLUSION: This retrospective study reports a substantial clinical benefit of Bev in patients with recurrent glioblastoma with an acceptable toxicity profile. As the panel of therapeutic option is still very limited in these tumors, this work supports the maintained use of Bev as a therapeutic option.

Neutral Processes Dominate Microbial Community Assembly in Atlantic Salmon, Salmo salar

In recent years, a wealth of studies has examined the relationships between a host and its microbiome across diverse taxa. Many studies characterize the host microbiome without considering the ecological processes that underpin microbiome assembly. In this study, the intestinal microbiota of Atlantic salmon, Salmo salar, sampled from farmed and wild environments was first characterized using 16S rRNA gene MiSeq sequencing analysis. We used neutral community models to determine the balance of stochastic and deterministic processes that underpin microbial community assembly and transfer across life cycle stage and between gut compartments. Across gut compartments in farmed fish, neutral models suggest that most microbes are transient with no evidence of adaptation to their environment. In wild fish, we found declining taxonomic and functional microbial community richness as fish mature through different life cycle stages. Alongside neutral community models applied to wild fish, we suggest that declining richness demonstrates an increasing role for the host in filtering microbial communities that is correlated with age. We found a limited subset of gut microflora adapted to the farmed and wild host environment among which Mycoplasma spp. are prominent. Our study reveals the ecological drivers underpinning community assembly in both farmed and wild Atlantic salmon and underlines the importance of understanding the role of stochastic processes, such as random drift and small migration rates in microbial community assembly, before considering any functional role of the gut microbes encountered.IMPORTANCE A growing number of studies have examined variation in the microbiome to determine the role in modulating host health, physiology, and ecology. However, the ecology of host microbial colonization is not fully understood and rarely tested. The continued increase in production of farmed Atlantic salmon, coupled with increased farmed-wild salmon interactions, has accentuated the need to unravel the potential adaptive function of the microbiome and to distinguish resident from transient gut microbes. Between gut compartments in a farmed system, we found a majority of operational taxonomic units (OTUs) that fit the neutral model, with Mycoplasma species among the key exceptions. In wild fish, deterministic processes account for more OTU differences across life stages than those observed across gut compartments. Unlike previous studies, our results make detailed comparisons between fish from wild and farmed environments, while also providing insight into the ecological processes underpinning microbial community assembly in this ecologically and economically important species.

Modulation of Rb phosphorylation and antiproliferative response to palbociclib: the preoperative-palbociclib (POP) randomized clinical trial

Background

The cyclin-dependent kinase 4 (CDK4)/6 inhibitor Palbociclib is a new standard treatment in hormone-receptor positive breast cancer patients. No predictive biomarkers have been identified and no pharmacodynamics has properly been described so far.

Patients and methods

Patients with early-breast cancer were randomized 3 : 1 to oral palbociclib 125 mg daily for 14 days until the day before the surgery versus no treatment. Primary objective was antiproliferative response defined as a natural logarithm of Ki67 expression at day 15 below 1. Secondary end points were subgroups analyses and safety. Exploratory analyses included search for predictive biomarkers. Immunostainings (Ki67, RB, pRB, p16, pAKT, pER, pCDK2, CyclinD1), FISH (CCND1) and gene expression (GE) arrays were carried out at baseline and at surgery. In addition, activating PIK3CA and AKT1 mutations were assessed at baseline.

Results

74 patients were allocated to palbociclib and 26 to control. Most patients (93%) were hormone-receptor (HR)-positive, whereas 8% were HER2-positive. Palbociclib led to significantly more antiproliferative responses when compared with control (58% versus 12%, P < 0.001), and to a significantly higher Ki67 decrease (P < 0.001). In the HR-positive/HER2-negative subgroup, this antiproliferative effect was even more marked in the palbociclib arm when compared with control (70% versus 9%, P < 0.001). Palbociclib treatment led also to a significantly higher decrease from baseline in phospho-Rb when compared with control (P < 0.001). Among treated patients, changes in Ki67 correlated with changes in phospho-Rb (Spearman rank r = 0.41, P < 0.0001). GE analyses confirmed a major effect on proliferation and cell cycle genes. Among treated patients, CCNE2 expression was significantly more decreased in antiproliferative responders versus nonresponders (P = 0.006).

Conclusion

Short-term preoperative palbociclib decreases Ki67 in early-breast cancer patients. Early decrease of Rb phosphorylation correlates with drug's effect on cell proliferation and could potentially identify patients with primary resistance.

Clinical trial registration

NCT02008734.

Oral etoposide in heavily pre-treated metastatic breast cancer: results from the ESME cohort and comparison with other chemotherapy regimens

INTRODUCTION

HER2-negative metastatic breast cancer (MBC) is a common setting in which chemotherapy could be effective even in later lines of treatment. Oral etoposide has demonstrated clinical activity in this setting in small-scale studies, but its efficacy has not been compared to that of other chemotherapy regimens.

METHODS

We used the ESME database (Epidemiological Strategy and Medical Economics), a real-life national French multicentre cohort of MBC patients initiating therapy between 1 January 2008 to 31 December 2014. HER2-negative MBC patients who received oral etoposide as > 3rd chemotherapy line and for more than 14 days were included. Primary objective was progression-free survival (PFS); secondary objectives were overall survival (OS), and propensity-score matched Cox models including comparison with other therapies in the same setting.

RESULTS

Three hundred forty-five out of 16,702 patients received oral etoposide and 222 were eligible. Median PFS was 3.2 months [95% CI 2.8-4] and median OS 7.3 months [95% CI 5.7-10.3]. Median PFS did not significantly differ according to the therapeutic line. The only prognostic factor for both PFS and OS was the MBC phenotype (hormone receptor-positive versus triple-negative, HR = 0.71 [95% CI 0.52-0.97], p = 0.028 for PFS and HR = 0.65 [0.46-0.92], p = 0.014 for OS). After matching for the propensity score, no differential effect on PFS or OS was observed between oral etoposide and other chemotherapy regimens administered in the same setting (HR = 0.94 [95% CI 0.77-1.15], p = 0.55 for PFS and HR = 1.10 [95% CI 0.88-1.37], p = 0.40 for OS).

CONCLUSION

Oral etoposide retains some efficacy in selected heavily pre-treated patients with HER2-negative MBC, with the advantages of oral administration.

Abstract P5-21-11: Benefit from palbociclib and fulvestrant based on previous fulvestrant and/or everolimus treatment. Based on a cohort of over 200 patients treated in a French compassionate program

Background: CDK4/6 inhibitors have been approved in the recent years for the treatment of advanced hormone receptor-positive breast cancer. For patients with resistance to previous endocrine therapy, the approval is based on the results of the PALOMA-3 trial testing palbociclib in addition to fulvestrant observing a progression-free survival (PFS) of 9.2 months. Nevertheless, in this study no previous treatment with fulvestrant was allowed and no information had been reported of efficacy after everolimus administration.

Patients and methods: We collected information from patients treated with palbociclib + fulvestrant in the context of a French compassionate access. We aimed at determining the benefit of this treatment in a real population to provide information about PFS in non-selected patients as well as efficacy of palbociclib and fulvestrant in patients previously treated with fulvestrant and/or everolimus. Median PFS were assessed by Kaplan-Meier survival analysis and compared with log-rank test.

Results: 206 patients were identified from 5 institutions. Mean age at treatment was 61 years (range 28 – 85). 55% presented with visceral disease. Lines at where palbociclib + fulvestrant treatment was administered were as follows: 1% 1st line, 8.3% 2nd line, 19.4% 3rd line, 13.6% 4th line, 10.2% 5th lignes and the remaining 47.6% had received ≥6 lines (median: 5 lines, range 1 to 15).

A total of 48% patients had previously been treated with fulvestrant. In a subsample of patient where the information was available (n=146), 67.8% patients had received everolimus in combination with endocrine therapy before palbociclib administration.

A total of 77 patients were still on treatment. Median PFS on fulvestrant-palbociclib treatment at the date of data cut-off was of 5.46 months (95% CI; 4.6 to 6.6 months). In a univariate analysis, there were no significant differences in median PFS for patients treated or not with previous fulvestrant, suggesting a potential effect of palbociclib to recover sensitivity to fulvestrant (4.7 months for previous fulvestrant treatment [95% CI 4.07 - 6.3 months] vs 6.1 months for no previous fulvestrant [95% CI; 6.3 - 8.02 months], p=0.3559).

Similarly, in the subsample of n=146 patients where information about previous everolimus treatment was available at data cut-off, benefit from palbociclib-fulvestrant was not affected by previous everolimus treatment (median PFS 4.8 months for previously treated [95% CI; 4.01 -7.8 months] vs 5.4 months for the untreated everolimus group [95% CI; 4.07 - 9.59 months], p=0.374).

Conclusions: Fulvestrant-palbociclib in the real life is associated with a median PFS of 5.5 months, which is below the results provided in the PALOMA-3 trial, reflecting a much more advanced population. Importantly, neither previous everolimus treatment nor fulvestrant therapy affected benefit from fulvestrant-palbociclib in this population in univariate analyses suggesting a potential recovery of fulvestrant sensitivity with CDK4/6 inhibition. Results from multivariate analyses and more detailed information about patients' characteristics and benefit from previous therapies will be provided.

Citation Format: Arnedos M, Rusquec P, Morelle M, Lebreton C, Jacquet E, Emile G, Aires J, Debled M, Frenel J-S, Augereau P, Cheaib B, Levy C, Bachelot T. Benefit from palbociclib and fulvestrant based on previous fulvestrant and/or everolimus treatment. Based on a cohort of over 200 patients treated in a French compassionate program [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-11.

Neoadjuvant chemotherapy (NACT) increases immune infiltration and programmed death-ligand 1 (PD-L1) expression in epithelial ovarian cancer (EOC)

Background

Lymphocytic infiltration at diagnosis is prognostic in EOC, however, the impact of NACT on tumour infiltrating lymphocytes (TILs) or PD-L1 expression remains poorly described.

Patients and methods

Patients with EOC and sequential samples (pre-NACT, post-NACT or relapse) were retrospectively identified. TILs were evaluated on whole sections; stromal TILs (sTILs) scored as percentage of stromal area with high sTILs defined as ≥50%; intra-epithelial TILs (ieTILs) scored semi-quantitatively (0-3) with high ieTILs ≥2. A smaller number were available for PD-L1 evaluation, cut-off for positivity was ≥5% staining.

Results

sTILs were detected in all tumours at diagnosis (range 2-90%, median 20%), with 22% (25/113) showing high sTILs. Among evaluable paired pre/post-NACT samples (N = 83), an overall increase in median sTILs from 20% to 30% was seen following NACT (P = 0.0005); individually the impact of NACT varied with sTILs increasing in 51% (42/83), decreasing in 25%, and stable in 24%. Post-NACT sTILs were predictive of platinum-free interval (PFI), patients with PFI ≥6 months had significantly higher post-NACT sTILs (sTILs 28% versus 18% for PFI <6 months, P = 0.026); pre-NACT sTILS were not predictive. At diagnosis, 23% showed high ieTILs, and following NACT 33% showed increasing ieTILs. Proportion of tumours with PD-L1-positive immune cells was 30% (15/50) pre-NACT and 53% (27/51) post-NACT (P = 0.026). Among paired tumours, 63% of PD-L1-negative tumours became positive after NACT, furthermore cisplatin induced PD-L1 expression in PD-L1-negative EOC cell lines. On multivariate analysis, high sTILs both pre- and post-NACT were independent prognostic factors for progression-free survival (PFS) (HR 0.49, P = 0.02 and HR 0.60, P = 0.05, respectively). No prognostic impact of ieTILs or PD-L1 expression was detected.

Conclusions

In EOC, sTILs levels are prognostic at diagnosis and remain prognostic after NACT. TILs and PD-L1 expression increase following NACT. Evaluation of immune parameters in the post-NACT tumour may help select patients for immunotherapy trials.

Pattern of tumor-infiltrating lymphocytes (TILs) and PD-L1 expression in primary and metastatic epithelial ovarian cancer (EOC)

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Background: Tumour immune response plays a critical role in progression and prognosis of EOC, however patterns of TILs and PD-L1 expression in primary and metastatic disease remain poorly described. Methods: Patients treated with neoadjuvant chemotherapy (NACT) for advanced EOC, between 2002-2014, and available sequential tumours (pre-NACT, post-NACT, or relapse) were retrospectively identified. Stromal TILs (sTILs) were evaluated according to the International TILs Working Group 2014 (Salgado 2015) on whole sections, and scored as a percentage of stromal area. Immune cell PD-L1 expression was evaluated by immunohistochemistry (E1L3N clone, Cell Signaling) in a smaller number of tumours. Cutoffs for analysis were: high sTILs ≥50%, PD-L1 positivity ≥5% membranous staining. Results: Among a total of 236 tumour samples from 150 patients (110 pre-NACT, 111 post-NACT, and 15 relapse tumours) median sTILs levels was significantly higher in metastatic tumours ( n=151) compared with primary tumours ( n=85) (median 30, IQR 10-50 vs. 15, IQR 5-30, p=0.0004). Among diagnostic samples, median sTILs level was 20 (IQR 10-45, n=85) in metastatic tumours compared with 10 (IQR 5-20, n =25) in primary tumours ( p=0064). Similarly in post-NACT samples, median sTILs level was 40 (IQR 15-60, n=51) in metastatic tumours compared with 20 (IQR 6.25-30, n=60) in primary tumours ( p=0026). Among relapse samples median sTILs level was 30 (IQR 10-50, n=15). Among all available samples ( n=97) PD-L1 positivity was detected in 33% (9/30) of primary and 50% (34/68) of metastatic tumours (Fisher’s exact test OR 2.3, 95%CI 0.94-5.4, p =0.08). Conclusions: In patients with EOC there is increased lymphocytic infiltration in both synchronous metastatic disease at diagnosis, and metachronous metastatic disease at relapse, compared with the primary tumour. This suggests increased immunogenicity as disease progresses. Furthermore, there is a trend towards upregulation of the PD-L1 immune checkpoint with disease progression.

The PI3K/Akt/mTOR pathway in ovarian cancer: therapeutic opportunities and challenges

The phosphatidylinositol 3 kinase (PI3K) pathway is frequently altered in cancer, including ovarian cancer (OC). Unfortunately, despite a sound biological rationale and encouraging activity in preclinical models, trials of first-generation inhibitors of mammalian target of rapamycin (mTOR) in OC have demonstrated negative results. The lack of patient selection as well as resistance to selective mTOR complex-1 (mTORC1) inhibitors could explain the disappointing results thus far. Nonetheless, a number of novel agents are being investigated, including dual mTORC1/mTORC2, Akt, and PI3K inhibitors. Although it is likely that inhibition of the PI3K/Akt/mTOR pathway may have little effect in unselected OC patients, certain histological types, such as clear cell or endometrioid OC with frequent phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit alpha (PIK3CA) and/or phosphatase and tensin homolog (PTEN) alterations, may be particularly suited to this approach. Given the complexity and redundancy of the PI3K signaling network, PI3K pathway inhibition may be most useful in combination with either chemotherapy or other targeted therapies, such as MEK inhibitors, anti-angiogenic therapy, and hormonal therapy, in appropriately selected OC patients. Here, we discuss the relevance of the PI3K pathway in OC and provide an up-to-date review of clinical trials of novel PI3K inhibitors alone or in combination with cytotoxics and novel therapies in OC. In addition, the challenges of drug resistance and predictive biomarkers are addressed.

The PI3K/Akt/mTOR pathway in ovarian cancer: therapeutic opportunities and challenges

The phosphatidylinositol 3 kinase (PI3K) pathway is frequently altered in cancer, including ovarian cancer (OC). Unfortunately, despite a sound biological rationale and encouraging activity in preclinical models, trials of first-generation inhibitors of mammalian target of rapamycin (mTOR) in OC have demonstrated negative results. The lack of patient selection as well as resistance to selective mTOR complex-1 (mTORC1) inhibitors could explain the disappointing results thus far. Nonetheless, a number of novel agents are being investigated, including dual mTORC1/mTORC2, Akt, and PI3K inhibitors. Although it is likely that inhibition of the PI3K/Akt/mTOR pathway may have little effect in unselected OC patients, certain histological types, such as clear cell or endometrioid OC with frequent phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit alpha (PIK3CA) and/or phosphatase and tensin homolog (PTEN) alterations, may be particularly suited to this approach. Given the complexity and redundancy of the PI3K signaling network, PI3K pathway inhibition may be most useful in combination with either chemotherapy or other targeted therapies, such as MEK inhibitors, anti-angiogenic therapy, and hormonal therapy, in appropriately selected OC patients. Here, we discuss the relevance of the PI3K pathway in OC and provide an up-to-date review of clinical trials of novel PI3K inhibitors alone or in combination with cytotoxics and novel therapies in OC. In addition, the challenges of drug resistance and predictive biomarkers are addressed.