[Current post-surgical treatment strategies in first-line ovarian cancer]

Although the management of epithelial ovarian cancer has evolved significantly over the past few years, it remains a public health issue, as most patients are diagnosed at an advanced stage and relapse after first line treatment. Chemotherapy remains the standard adjuvant treatment for International Federation of Gynecology and Obstetrics (FIGO) stage I and II tumors, with some exceptions. For FIGO stage III/IV tumors, carboplatin- and paclitaxel-based chemotherapy are the standard of care, in combination with targeted therapies, especially bevacizumab and/or poly-(ADP-ribose) polymerase inhibitors, that have become a key milestone of first-line treatment. Our decision making for the maintenance therapy is based on the FIGO stage, tumor histology, timing of surgery (i.e. primary or interval debulking surgery), residual tumor, response to chemotherapy, BRCA mutation and homologous recombination (HR) status.

APR-246 increases tumor antigenicity independent of p53

We previously reported that activation of p53 by APR-246 reprograms tumor-associated macrophages to overcome immune checkpoint blockade resistance. Here, we demonstrate that APR-246 and its active moiety, methylene quinuclidinone (MQ) can enhance the immunogenicity of tumor cells directly. MQ treatment of murine B16F10 melanoma cells promoted activation of melanoma-specific CD8+ T cells and increased the efficacy of a tumor cell vaccine using MQ-treated cells even when the B16F10 cells lacked p53. We then designed a novel combination of APR-246 with the TLR-4 agonist, monophosphoryl lipid A, and a CD40 agonist to further enhance these immunogenic effects and demonstrated a significant antitumor response. We propose that the immunogenic effect of MQ can be linked to its thiol-reactive alkylating ability as we observed similar immunogenic effects with the broad-spectrum cysteine-reactive compound, iodoacetamide. Our results thus indicate that combination of APR-246 with immunomodulatory agents may elicit effective antitumor immune response irrespective of the tumor's p53 mutation status.

Circulating Tumor DNA from Ascites as an alternative to tumor sampling for genomic profiling in ovarian cancer patients

Genomic testing is crucial for the management of ovarian cancer. DNA from biopsies at diagnostic laparoscopies or interval debulking surgery after neoadjuvant chemotherapy, has a high failure rate. At relapse, biopsies may not be feasible. The aim of our study was to evaluate the feasibility and usefulness of measuring genomic instability score (GIS) on cell-free DNA (cfDNA) from ascites.Patients enrolled in a prospective study (NCT03010124) consented to analysis of biological samples. CfDNA was extracted from 1 to 4 ml of double-centrifuged fresh ascites. Targeted Next-generation sequencing (NGS) including TP53 mutation (TP53m) was performed on cfDNA to confirm the presence of tumor cfDNA. Single Nucleotide Polymorphism Array estimating somatic copy number alterations (SCNA) was performed to calculate GIS for Homologous-Recombination deficiency (HRD).Twenty nine ascites were collected from 20 patients with suspected or confirmed OC. 93% (27/29) samples had detectable cfDNA (median 1120 ng [24-5732]) even when obtained during chemotherapy. A deleterious mutation was identified in 100%, with high allelic frequencies (median 60% [3.3-87%]), confirming that cfDNA was tumoral. SCNA analyses on 17 patients showed 11 high GIS, and 6 low GIS. 4 patients with confirmed BRCA mutation had a high GIS on ascites. When available from the same patient, SCNA profiles on ascites and tumor were superimposable.Ascites is frequent at diagnosis and relapse and yields large amounts of tumoral cfDNA. SCNA analysis on ascitic cfDNA is feasible and can detect the same HRD scar as tumor testing. Ascites could provide an alternative to tumor sampling for HRD and BRCA testing.

Clinical Relevance of BRCA1 Promoter Methylation Testing in Patients with Ovarian Cancer

PURPOSE

Homologous recombination deficiency (HRD) is closely related to PARP inhibitor (PARPi) benefit in ovarian cancer. The capacity of BRCA1 promoter methylation to predict prognosis and HRD status remains unclear. We aimed to correlate BRCA1 promoter methylation levels in patients with high-grade ovarian cancer to HRD status and clinical behavior to assess its clinical relevance.

EXPERIMENTAL DESIGN

This is a retrospective monocentric analysis of patients centrally tested for genomic instability score (GIS) by MyChoice CDx (Myriad Genetics). The detection of BRCA1 promoter methylation and quantification of methylation levels were performed by quantitative droplet digital PCR methodology. High BRCA1 methylation was defined as ≥70% and deemed to be associated with homozygous silencing.

RESULTS

Of 100 patients, 11% harbored a deleterious BRCA1/2 mutation. GIS was considered positive (score ≥ 42) for 52 patients and negative for 48 patients. Using a 70% cutoff, 19% (15/79) of BRCA wild-type ovarian cancer had high BRCA1 methylation levels. All of the highly methylated tumors were classified as HRD, achieving a positive predictive value of 100%. We detected 14% (11/79) low-methylated tumors (1%-69%), and all of them were also classified as HRD. Mean GIS was 61.5 for BRCAmut, 66.4 for high-BRCAmeth, 58.9 for low-BRCAmeth, and 33.3 for BRCAwt unmethylated (P < 0.001). Low methylation levels detected in samples previously exposed to chemotherapy appeared to be associated with poor outcome post-platinum.

CONCLUSIONS

Patients with ovarian cancer with high levels of BRCA1 hypermethylation are very likely to have high GIS and therefore represent good candidates for PARPi treatment. These results may be highly relevant to other tumor types for HRD prediction. See related commentary by Garg and Oza, p. 2957.

Combined Tumor-Based BRCA1/2 and TP53 Mutation Testing in Ovarian Cancer

Somatic/germline BRCA1/2 mutations (m)/(likely) pathogenic variants (PV) (s/gBRCAm) remain the best predictive biomarker for PARP inhibitor efficacy. As >95% of high-grade serous ovarian cancers (HGSOC) have a somatic TP53m, combined tumor-based BRCA1/2 (tBRCA) and TP53 mutation testing (tBRCA/TP53m) may improve the quality of results in somatic BRCAm identification and interpretation of the 'second hit' event, i.e., loss of heterozygosity (LOH). A total of 237 patients with HGSOC underwent tBRCA/TP53m testing. The ratio of allelic fractions (AFs) for tBRCA/TP53m was calculated to estimate the proportion of cells carrying BRCAm and to infer LOH. Among the 142/237 gBRCA results, 16.2% demonstrated a pathogenic/deleterious variant (DEL) gBRCA1/2m. Among the 195 contributive tumor samples, 43 DEL of tBRCAm (22.1%) were identified (23 gBRCAm and 20 sBRCAm) with LOH identified in 37/41 conclusive samples. The median AF of TP53m was 0.52 (0.01-0.93), confirming huge variability in tumor cellularity. Initially, three samples were considered as wild type with <10% cellularity. However, additional testing detected a very low AF (<0.05) in both BRCA1/2m and TP53m, thus reidentifying them as sBRCA1/2m. Combined tBRCA/TP53m testing is rapid, sensitive, and identifies somatic and germline BRCA1/2m. AF TP53m is essential for interpreting sBRCA1/2m in low-cellularity samples and provides indirect evidence for LOH as the 'second hit' of BRCA1/2-related tumorigenesis.

Increased p53 expression induced by APR-246 reprograms tumor-associated macrophages to augment immune checkpoint blockade

In addition to playing a major role in tumor cell biology, p53 generates a microenvironment that promotes antitumor immune surveillance via tumor-associated macrophages. We examined whether increasing p53 signaling in the tumor microenvironment influences antitumor T cell immunity. Our findings indicate that increased p53 signaling induced either pharmacologically with APR-246 (eprenetapopt) or in p53-overexpressing transgenic mice can disinhibit antitumor T cell immunity and augment the efficacy of immune checkpoint blockade. We demonstrated that increased p53 expression in tumor-associated macrophages induces canonical p53-associated functions such as senescence and activation of a p53-dependent senescence-associated secretory phenotype. This was linked with decreased expression of proteins associated with M2 polarization by tumor-associated macrophages. Our preclinical data led to the development of a clinical trial in patients with solid tumors combining APR-246 with pembrolizumab. Biospecimens from select patients participating in this ongoing trial showed that there was a suppression of M2-polarized myeloid cells and increase in T cell proliferation with therapy in those who responded to the therapy. Our findings, based on both genetic and a small molecule–based pharmacological approach, suggest that increasing p53 expression in tumor-associated macrophages reprograms the tumor microenvironment to augment the response to immune checkpoint blockade.

Abstract 1951: Circulating tumor cell-derived explant models reveal DNA damage response-based therapeutic opportunities in non-small cell lung cancer

Background: DNA damage and genomic instability contribute to non-small cell lung cancer (NSCLC) etiology and progression. However, their therapeutic exploitation is disappointing. CTC-derived eXplants (CDX) offer systems for mechanistic investigation of CTC metastatic potency and biology-driven therapeutic testings. We perform in-depth molecular and functional characterization of CDX models and demonstrate that targeting defects in the DNA damage response (DDR) and genome integrity regulators impedes CTC-driven metastasis in NSCLC.

Methods: CTCs were enriched from 30 mL blood samples of 56 advanced NSCLC patients and implanted subcutaneously into Nod/Scid-IL2Rγ-/- (NSG) mice. Tumors were palpable within a median of 108 days. Among the four CDX models established, three CDX-derived cell lines (GR-CDXL1, GR-CDXL3, GR-CDXL4) were obtained. CDX and cell lines were characterized by immunofluorescence (IF), immunohistochemistry and whole-exome sequencing (WES). Chromosomal instability (CIN) and DDR activity were evaluated by IF and western blot. Gene expression was quantified by qRT-PCR. Tumorigenic potential of CDX-derived cell lines was assessed in the chick embryo chorioallantoic membrane and NSG mice engrafted intravenously. IC50 was assessed using CellTiter-Glo®.

Results: Four CDX models and three CDX-derived cell lines were established from NSCLC CTCs and recapitulated patient tumor histology (available for three patients) and response to platinum-based chemotherapy. WES analysis showed considerable mutational landscape similarity between the CDX (GR-CDXL1, GR-CDXL2, GR-CDXL3, GR-CDXL4), corresponding patient tumor biopsy and/or single CTCs. Truncal alterations in key DDR and genome integrity-related genes were prevalent across models and assessed as therapeutic targets in vitro, in ovo and in vivo. GR-CDXL1 presented homologous recombination deficiency linked to bi-allelic BRCA2 mutation, FANCA deletion and unrepaired DNA lesions post-mitosis. GR-CDXL1 cells were sensitive to PARP inhibitor (PARPi) olaparib, despite chemoresistance, which challenges the current clinical hypothesis claiming that chemosensitive NSCLC patients should respond to PARPi. Targeting CIN through centrosome clustering inhibition in GR-CDXL3 impeded tumor growth in ovo and in vivo. In GR-CDXL4, olaparib sensitivity was dictated by SLFN11 overexpression, which also correlated with increased neuroendocrine marker expression at patient disease progression, suggesting a predictive value of SLFN11 in histological transformation of NSCLC into SCLC.

Conclusion: This study unravels distinct DDR profiles as a central mechanism underpinning CTC metastatic potency. Our CDX models provide a robust platform for ex vivo drug testing of DDR-targeted strategies to expand patient categories that may benefit from precision medicine in metastatic NSCLC.

Citation Format: Tala Tayoun, Vincent Faugeroux, Marianne Oulhen, Olivier Deas, Judith Michels, Laur Brulle-Soumare, Stefano Cairo, Jean-Yves Scoazec, Virginie Marty, Agathe Aberlenc, David Planchard, Jordi Remon, Santiago Ponce, Benjamin Besse, Patricia Kannouche, Jean-Gabriel Judde, Patrycja Pawlikowska, Françoise Farace. Circulating tumor cell-derived explant models reveal DNA damage response-based therapeutic opportunities in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1951.

Abstract 1291: APR-246 enhances tumor immunogenicity even in the absence of p53

Despite the significant success of immunotherapy, more than 40% of cancer patients remain unresponsive or exhibit an insufficient response. Well-designed combinations of targeted therapy and immunotherapy have the potential to increase effectiveness of cancer treatment and overcome the absence of response to either therapy alone. Since targeted therapies that enhance tumor antigenicity can enhance the effectiveness of immune based therapies, we have built a compendium of in vitro and in vivo assays to evaluate the effect of multiple immunogenic drugs. In these assays, we use the preclinical melanoma cell line B16-F10 model as it is highly metastatic and responds poorly to immunotherapy alone. The tumor suppressor p53 is a key target both in terms of targeted therapy owing to its role in halting tumor progression as well as in combination with immunotherapy, since p53 has varied roles in immune modulation. APR-246 can activate p53 and elicit some p53-independent effects in various tumor models predominantly through the induction of endoplasmic reticulum stress and oxidative stress. Since these cellular stressors (including p53) have been shown to be capable of rendering tumor cells immunogenic, we hypothesized that APR-246 may also increase the antigenicity of tumor cells. Indeed, we observed that treatment of B16 cells with APR-246 increases their MHC expression. Additionally, in our in vitro co-culture assays, cells treated with APR-246 were able to activate antigen-specific cytotoxic T cells either directly or via CD11c+ cells. We also observed that mice immunized with APR-246-treated B16 cells and then implanted with healthy untreated melanoma cells, were able to confer prolonged tumor free survival. Taken together, we believe that APR-246 has the potential to make for a strong combination with immunomodulatory therapies owing to its immunogenic potential. Based on these observations, we rationally designed a combination treatment regimen that would further enhance the immunogenic effects elicited by APR-246 on tumor cells. The triple combination of APR-246 with the TLR4 agonist, Monophosphoryl lipid A (MPL) and the anti-CD40 antibody significantly reduced the growth of B16 tumor in C57BL/6J mice. Strikingly, using CRISPR generated B16 p53 KO cells, we have discovered that these effects of APR-246 exist even in the absence of p53, albeit slightly reduced. Therefore, our results indicate that combination of APR-246 with immunomodulatory agents may be effective in treating cancers irrespective of their genetic status of p53. Our finding suggests that drugs with immunogenic potential, in addition to their original therapeutic indication, such as APR-246 are good candidates for the improvement of various clinically relevant immune modulatory therapies. Note: D.V. and J.M. contributed equally to this work.

Citation Format: Divya Venkatesh, Judith Michels, Cailian Liu, Sadna Budhu, Mariam M. George, Lars Abrahmsen, Roberta Zappasodi, Jedd D. Wolchok, Taha Merghoub. APR-246 enhances tumor immunogenicity even in the absence of p53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1291.

Cancer cell-autonomous overactivation of PARP1 compromises immunosurveillance in non-small cell lung cancer

Background

High activity of poly(ADP-ribose) polymerase-1 (PARP1) in non-small cell lung cancer (NSCLC) cells leads to an increase in immunohistochemically detectable PAR, correlating with poor prognosis in patients with NSCLC, as well as reduced tumor infiltration by cytotoxic T lymphocytes (CTLs). Intrigued by this observation, we decided to determine whether PARP1 activity in NSCLC cells may cause an alteration of anticancer immunosurveillance.

Methods

Continuous culture of mouse NSCLC cells in the presence of cisplatin led to the generation of cisplatin-resistant PAR^high clones. As compared with their parental controls, such PAR^high cells formed tumors that were less infiltrated by CTLs when they were injected into immunocompetent mice, suggesting a causative link between high PARP1 activity and compromised immunosurveillance. To confirm this cause-and-effect relationship, we used CRISPR/Cas9 technology to knock out PARP1 in two PAR^high NSCLC mouse cell lines (Lewis lung cancer [LLC] and tissue culture number one [TC1]), showing that the removal of PARP1 indeed restored cisplatin-induced cell death responses.

Results

PARP1 knockout (PARP1^KO) cells became largely resistant to the PARP inhibitor niraparib, meaning that they exhibited less cell death induction, reduced DNA damage response, attenuated metabolic shifts and no induction of PD-L1 and MHC class-I molecules that may affect their immunogenicity. PAR^high tumors implanted in mice responded to niraparib irrespective of the presence or absence of T lymphocytes, suggesting that cancer cell-autonomous effects of niraparib dominate over its possible immunomodulatory action. While PAR^high NSCLC mouse cell lines proliferated similarly in immunocompetent and T cell-deficient mice, PARP1^KO cells were strongly affected by the presence of T cells. PARP1^KO LLC tumors grew more quickly in immunodeficient than in immunocompetent mice, and PARP1^KO TC1 cells could only form tumors in T cell-deficient mice, not in immunocompetent controls. Importantly, as compared with PAR^high controls, the PARP1^KO LLC tumors exhibited signs of T cell activation in the immune infiltrate such as higher inducible costimulator (ICOS) expression and lower PD-1 expression on CTLs.

Conclusions

These results prove at the genetic level that PARP1 activity within malignant cells modulates the tumor microenvironment.

PemBOv trial: Pembrolizumab plus bevacizumab with or without pegylated liposomal doxorubicin-based chemotherapy in patients with platinum-resistant ovarian cancer

5575

Background: Few platinum resistant ovarian cancer (PROvC) patients respond to anti-PD1 monotherapy (ORR 7.6%) with little impact on survival (OS 10.1 mo). Among responders the median duration of response is impressive (18.7 mo) (Hamanishi 2021). Methods: We have evaluated the combination of pembrolizumab (200mg), with bevacizumab (400mg) for 6 cycles plus minus peglyated liposomal doxorubicin (PLD) q3w in PROvC patients with no limit in previous treatment lines, allowed to be previously treated with bevacizumab. An initial safety run evaluated the dual combination of pembrolizumab plus PLD (cohort A). The triple combination was evaluated at MTD-1 and at MTD of PLD (30mg/m2 q3w) (cohort C). The dual combination of pembrolizumab + bevacizumab was run in parallel (cohort B). This is an open label phase I trial with a modified toxicity probability interval design. The evaluation criteria endpoints were safety and efficacy. Pharmacokinetics of bevacizumab were evaluated. NCT03596281 Results: A total of 47 patients (pts) were enrolled between January 2019 and February 2021. Median age was 70 years (38-77). 30/12 pts (63.8/25.5%) had an initial FIGO stage III/IV, 44 pts (93.6%) had a HGSOC. 40 pts (85.1%) underwent surgery, out of which 13 pts (32.5%) had a primary debulking. BRCA mutations were present in 9 pts (19.1%). Pts had a median of 3 previous treatment lines (0-13), including pretreatment with antiangiogenic agents in 36 (76.6%) and PARP inhibitors in 21 pts (44.7%). No DLT was reported. Grade 3/4 treatment-related adverse events were reported in 2 pts (30%), 4 (20%) and 11 (50%) in cohorts A, B and C respectively. The ORR was 0, 26.3 (95% CI 6.5-46.1) and 30% (9.9-50.1) with a DCR of 0, 78.9 and 75% in cohorts A, B and C respectively. According to investigator assessment, the median PFS was 2.1, 4.7 and 4.8 mo (table). The blinded independent central review is currently under evaluation. A large inter-patient variability in bevacizumab plasma concentrations was observed among patients. The 400 mg flat dosing achieved residual concentrations similar to that of 5 mg/kg Q2W or 7.5 mg/kg q3w (51± 30 μg/ml in cohort B and 63 ± 55 μg/ml in cohort C (p>0.05) after C1). Overall, 22 % of pts of cohort B and 18 % of cohort C showed trough levels below the targeted threshold (i.e. < 25 μg/ml). Correlative studies are ongoing. Conclusions: Short-term flat dose bevacizumab potentiates the response to anti-PD1 therapy even in the absence of chemotherapy in heavily pre-treated PROvC patients. The long-term treatment with bevacizumab could potentially improve the outcome. The combination of anti-PD-1 plus anti-angiogenic agents should be a backbone for the treatment of PROvC patients. Clinical trial information: NCT03596281. [Table: see text]

Targeting genome integrity dysfunctions impedes metastatic potency in non-small-cell lung cancer circulating tumor cell-derived eXplants

DNA damage and genomic instability contribute to non–small cell lung cancer (NSCLC) etiology and progression. However, their therapeutic exploitation is disappointing. CTC-derived explants (CDX) offer systems for mechanistic investigation of CTC metastatic potency and may provide rationale for biology-driven therapeutics. Four CDX models and 3 CDX-derived cell lines were established from NSCLC CTCs and recapitulated patient tumor histology and response to platinum-based chemotherapy. CDX (GR-CDXL1, GR-CDXL2, GR-CDXL3, GR-CDXL4) demonstrated considerable mutational landscape similarity with patient tumor biopsy and/or single CTCs. Truncal alterations in key DNA damage response (DDR) and genome integrity–related genes were prevalent across models and assessed as therapeutic targets in vitro, in ovo, and in vivo. GR-CDXL1 presented homologous recombination deficiency linked to biallelic BRCA2 mutation and FANCA deletion, unrepaired DNA lesions after mitosis, and olaparib sensitivity, despite resistance to chemotherapy. SLFN11 overexpression in GR-CDXL4 led to olaparib sensitivity and was in coherence with neuroendocrine marker expression in patient tumor biopsy, suggesting a predictive value of SLFN11 in NSCLC histological transformation into small cell lung cancer (SCLC). Centrosome clustering promoted targetable chromosomal instability in GR-CDXL3 cells. These CDX unravel DDR and genome integrity–related defects as a central mechanism underpinning metastatic potency of CTCs and provide rationale for their therapeutic targeting in metastatic NSCLC.

Evaluating immune response in vitro in a relevant microenvironment: a high-throughput microfluidic model for clinical screening

Aim

Functional screening of new pharmaceutical compounds requires clinically relevant models to monitor essential cellular and immune responses during cancer progression, with or without treatment. Beyond survival, the emergence of resistant tumor cell clones should also be considered, including specific properties related to plasticity, such as invasiveness, stemness, escape from programmed cell death, and immune response. Numerous pathways are involved in these processes. Defining the relevant ones in the context of a specific tumor type will be key to designing an appropriate combination of inhibitors. However, the diversity and potential redundancy of these pathways remain a challenge for therapy.

Methods

A new microfluidic device developed by Okomera was dedicated to the screening of drug treatment for breast cancer. This microchip includes 150 droplet-trapping microwells, offering multi-chip settings and multiple treatment choices.

Results

After validating the system with established cell lines and a panel of drugs used clinically at Gustave Roussy, preclinical experiments were initiated including patient-derived xenograft (PDX) and primary tumor cells-derived tumoroids with the collaboration of Gustave Roussy clinicians. Tumor-isolated lymphocytes were also added to the tumoroids, using secondary droplets in proof-of-concept experiments.

Conclusions

These results show the relevance of the methodology for screening large numbers of drugs, a wide range of doses, and multiple drug combinations. This methodology will be used for two purposes: 1) new drug screening from the compound library, using the high throughput potential of the chip; and 2) pre-clinical assay for a two-weeks response for personalized medicine, allowing evaluation of drug combinations to flag an optimized treatment with potential clinical application.

355 Pembrolizumab and bevacizumab in platinum resistant epithelial ovarian cancer patients

Background

There is a medical need in platinum resistant ovarian cancer patients. Median progression-free survival (PFS) is 3.4 months with chemotherapy and 6.7 months with chemotherapy-bevacizumab combination regimens.1 RECIST overall response rate (ORR) is 11.8% and 27.3%, respectively. The ORR is 15.9% for bevacizumab as a monotherapy with a median PFS of 4.4 months.2

Methods

NCT03596281 An open-label phase 1b trial with a modified toxicity probability interval design to evaluate the combination of a flat dose of 400mg bevacizumab for 6 cycles and 200mg pembrolizumab until disease progression, unacceptable toxicity or completed 24 months of treatment in patients with platinum resistant ovarian cancer. The primary evaluation criteria is safety, the secondary endpoint is the efficacy.

Results

19 patients have been enrolled between January 2019 and February 2021 in 6 French centers. Patients‘ characteristics are reported (table 1). No dose limiting toxicities were observed. Grade 3 treatment related adverse events occurred in 3 patients (i.e. arterial thromboembolism, bowel perforation, proteinuria and sepsis). No grade 4/5 toxicities were induced. A median of 7 cycles (range 3–14) were administered. Median follow-up of patients was 4.1 months (1.8–23). The RECIST ORR was 26.3% (1 complete response and 4 partial responses) (table 2). The disease control rate was 78.9%. The time to progression was not yet reached in 6 patients. The ORR was equivalent whether patients have been pretreated or not with bevacizumab (27.3 and 25% respectively) (table 3). The ORR according to the combined positive score (CPS) for the evaluation of PD-L1 was 50.0% for CPS≥10% (n=4), 30.0% for a CPS≥1% (n=10) and 25.0% for CPS<1 (n=8) (table 4).

Conclusions

A chemotherapy-free regimen combining pembrolizumab and bevacizumab was well tolerated and showed encouraging results in heavily pretreated platinum resistant ovarian cancer patients independent of their previous challenge with antiangiogenic agents.

Acknowledgements

Funding for this research was provided by Fondation Cancer du Luxembourg and Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

Trial Registration

NCT03596281

References

Pujade-Lauraine E, et al. Bevacizumab combined with chemotherapy for platinum-resistant recurrent ovarian cancer: The AURELIA open-label randomized phase III trial. J Clin Onco Off J Am Soc Clin Oncol 32,1302–1308 (2014).

Cannistra SA, et al. Phase II study of bevacizumab in patients with platinum-resistant ovarian cancer or peritoneal serous cancer. J Clin Oncol Off J Am Soc Clin Oncol 33,5180–5186 (2007).

Ethics Approval

This study was approved by CPP Sud Méditerranée V institution’s Ethics Board; approval number 18.020 (EudraCT number 2017-004197-34).

Consent

Written informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.

Pyridoxal kinase and poly(ADP-ribose) affect the immune microenvironment of locally advanced cancers

Malignant cells adapt to the hostile tumor microenvironment by escaping from, or actively suppressing, anticancer immune responses. In the past, we reported that reduced synthesis of active vitamin B6 (due to downregulation of pyridoxal kinase) or overactivation of poly(ADP-ribose) polymerase confers resistance to chemotherapy with cisplatin. Recently, we found that these prognostically adverse alterations in oncometabolism also correlate with the rarefaction of immune effectors in the tumor bed.

Metabolic features of cancer cells impact immunosurveillance

Background

Tumors rewire their metabolism to achieve robust anabolism and resistance against therapeutic interventions like cisplatin treatment. For example, a prolonged exposure to cisplatin causes downregulation of pyridoxal kinase (PDXK), the enzyme that generates the active vitamin B6, and upregulation of poly ADP-ribose (PAR) polymerase-1 (PARP1) activity that requires a supply of nicotinamide (vitamin B3) adenine dinucleotide. We investigated the impact of the levels of PDXK and PAR on the local immunosurveillance (ie, density of the antigen presenting cells and adaptive immune response by CD8 T lymphocytes) in two different tumor types.

Methods

Tumors from patients with locally advanced cervical carcinoma (LACC) and non-small cell lung cancer (NSCLC) were stained for PAR, PDXK, dendritic cell lysosomal associated membrane glycoprotein (DC-LAMP) and CD8 T cell infiltration. Their correlations and prognostic impact were assessed. Cisplatin-resistant NSCLC cell clones isolated from Lewis-lung cancer (LLC) cells were evaluated for PAR levels by immunoblot. Parental (PAR^low) and cisplatin-resistant (PAR^high) clones were subcutaneously injected into the flank of C57BL/6 mice. Tumors were harvested to evaluate their immune infiltration by flow cytometry.

Results

The infiltration of tumors by CD8 T and DC-LAMP⁺ cells was associated with a favorable overall survival in patients with LACC (p=0.006 and p=0.008, respectively) and NSCLC (p<0.001 for both CD8 T and DC-LAMP cells). We observed a positive correlation between PDXK expression and the infiltration by DC-LAMP (R=0.44, p=0.02 in LACC, R=0.14, p=0.057 in NSCLC), and a negative correlation between PAR levels and CD8 T lymphocytes (R=−0.39, p=0.034 in LACC, R=−0.18, p=0.017 in NSCLC). PARP1 is constitutively hyperactivated in cisplatin-resistant LLC cells manifesting elevated intracellular levels of poly(ADP-ribosyl)ated proteins (PAR^high). Tumors formed by such cancer cells injected into immunocompetent mice were scarcely infiltrated by CD8 T (p=0.028) and antigen presenting cells (p=0.086).

Conclusions

Oncometabolic features can impact local immunosurveillance, providing new functional links between cisplatin resistance and therapeutic failure.

Volatile fatty acid platform - a cornerstone for the circular bioeconomy

Annually, the EU produces more than 100 million tonnes of urban biowaste, which is largely under-valorized and in some cases even still landfilled without any energy or material recovery. If Europe wants to be ready for the future, it will need to make better use of this large biomass potential within a circular economy approach. The research project funded by the European Commission under the Horizon 2020 programme entitled 'VOLATILE-Biowaste derived volatile fatty acid platform for biopolymers, bioactive compounds and chemical building blocks' aimed to produce volatile fatty acids (VFAs) from biowaste for reprocessing into products, materials or substances to close the material loop. During the project, the partners were able to obtain average volatile fatty acid yields of 627 g COD/kg organic matter (OM) for food waste, 448 g COD/kg OM for separately collected vegetable, garden and fruit waste (VGF) and 384 g COD/kg OM for the organic fraction of municipal solid waste (OF-MSW) at concentrations ranging from 12 to 48 g/L, 6 to 40 g/L and 13 to 26 g/L, respectively. A membrane filtration cascade consisting of micro-, ultra- and nano-filtration followed by reverse osmosis was identified as a feasible way to purify and concentrate the VFA effluent, making them a suitable carbon source for further fermentation processes. Besides technical optimization, socio-economic and legal aspects associated with this platform technology were also studied and show that although this technology is still in development, it is providing an answer to changing societal and market expectations both regarding organic waste treatment and bio-based production strategies. Based on the current technological, economic and market evolutions, it is expected that the VFAP will play an important role in organic waste treatment in the coming years.

Pembrolizumab in combination with bevacizumab and pegylated liposomal doxorubicin in patients with platinum-resistant epithelial ovarian cancer

5522

Background: There is a medical unmet need for effective treatments in platinum resistant ovarian cancer patients. We assessed the safety and efficacy of a combination of pembrolizumab with bevacizumab and pegylated liposomal doxorubicin (PLD). Methods: This is an open-label phase 1b trial in patients ECOG 0 or 1 with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer. The safety of the dual combinations of pembrolizumab with bevacizumab or with PLD were previously evaluated in 6 patients respectively. In the absence of dose limiting toxicities (DLT) the triple combination was evaluated at a maximum tolerated dose (MTD)-1 for PLD in 3 patients and in the absence of DLT at MTD. The sample size was calculated according to the modified toxicity probability interval design. The primary evaluation criteria was the safety, the secondary endpoint was the outcome. Pharmacokinetics of the flat dose of bevacizumab will be evaluated. Results: 22 patients were enrolled from September 2019 until June 2020 in six French centers. 3 initial patients have been treated at 20mg/m2 of PLD (MTD-1) and 19 patients were treated at the dose of 30mg/m2 of PLD (MTD) combined with 200mg of pembrolizumab until progression, unacceptable toxicity, or withdrawal of consent and 400mg of bevacizumab for a total of six cycles. The patients’ characteristics are reported in the table. No DLT occurred. Grade 3 palmar-plantar erythrodysesthesia were reported in 4 patients. The recommended phase II dose of PLD was 30mg/m2 in combination with pembrolizumab and bevacizumab. For patients treated at MTD, the overall response rate was 32% (6 partial responses) with 74% of clinical benefit with a durable response in 10 patients (53%). Median number of cycles was 7.5 (2 to not reached). Two patients are still on treatment. Correlative studies are ongoing. Conclusions: The combination was well tolerated and demonstrated clinical benefit in 74% platinum resistant ovarian cancer patients with durable response (>6 months) in 53% of patients. Clinical trial information: NCT03596281. [Table: see text]

Impact of young age on platinum response in women with epithelial ovarian cancer: Results of a large single-institution registry

OBJECTIVE

In young women, EOC is a rare disease with an uncertain genetic and biological substrate.

METHODS

We report a long follow-up of EOC patients treated at Gustave Roussy between 1990 and 2009. We matched young patients aged ≤30 years to randomly selected older patients aged ≥40 years according to known prognostic factors (i.e. FIGO stage, histology and surgical residual disease) and the date of diagnosis with a threshold at the year 2000 to balance the treatment procedures.

RESULTS

EOC was diagnosed in 68 patients aged ≤30 years matched with 111 patients aged ≥40 years. Low-grade (LG) (i.e. serous and endometrioid) (52%, n = 35) and mucinous (i.e. 23%, n = 16 infiltrative and 12% n = 8 expansile) tumors are prevalent. High-grade (HG) tumors are rare (7%, n = 5). Early stage diseases (53%, n = 36 FIGO I/II) are predominant. Response to platinum based chemotherapy is observed to be inferior in young patients as compared to matched older patients (ORR, 29 vs 84% p = 0.0002). For HG tumors the PFS is of 0% at 5 and 10 years in younger as compared to 30% in older patients. No difference in PFS (median 4.9 vs 9.8 ms, p = 0.58) and OS (not reached vs 15.3 ms, p = 0.47) is found overall among younger and older patients respectively. The median follow-up was 72 months (range, 11-288 months). No genetic abnormalities were found.

CONCLUSIONS

Young EOC patients are most often diagnosed at an early FIGO stage with LG serous or mucinous histology. Tumors are significantly more resistant to platinum-based chemotherapy in younger patients.

Prognostic value of dendritic cells in locally advanced cervical cancer patients

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Background: Cervical cancer is a Human papillomaviruses (HPV)-related disease. T cell infiltration is reported to be associated with a positive prognosis. We evaluated the prognostic value of the tumor-infiltrating dendritic cells (DC). Targeting this immune compartment might be clinically relevant. Methods: We characterized by immunohistochemistry the Dendritic cell lysosomal associated membrane glycoprotein (DC-Lamp) and CD8 T cell infiltration (high/low according to the median density) in patients with locally advanced cervical cancer (LACC) undergoing curative-intent concurrent chemoradiation followed by uterovaginal brachytherapy boost. They were treated in our institution between March 2004 and August 2011. The image acquisition was performed with a Zeiss Axio Scan Z1 microscope. CD8 T cells were detected using an algorithm created in Visiopharm software on manually selected regions of interest (ROI) and DC-Lamp was detected manually. We exported the number of cells and the surface of ROI to calculate the density. Results: A total of 91 patients were identified, with a median follow-up of 4.2 years (range: 0.1-10.3). Patient’s characteristics are listed in the table. DC-Lamphigh (n = 45) LACC patients showed a positive prognosis for overall survival (OS) by univariate (Odds Ratio (OR) = 0.20 [0.06 – 0.72], p = 0.013) and multivariate analyses (incorporating FIGO stage) (OR = 0.17 [0.05 – 0.61], p = 0.006). There was a positive correlation between DC-Lamp and CD8 (R = 0,25 et p = 0,095), which is significant in squamous cell carcinoma patients (R = 0.38, p = 0.039). There was a trend for improved risk stratification for the simultaneous assessment of DC-Lamp and CD8 levels, with DC-Lamphigh/CD8high patients having the best prognosis and DC-Lamplow/CD8low patients having the worst prognosis (p = 0.074). Conclusions: LACC patients with high intratumoral DC density have a favorable outcome. These results underscore the clinical potential of therapeutic strategies that target DC (e.g. Toll like receptor agonists) to render more patients responsive to immune checkpoint blockers. [Table: see text]

T-cell bispecific antibodies in node-positive breast cancer: novel therapeutic avenue for MHC class I loss variants

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) represent a prognostic factor for survival in primary breast cancer (BC). Nonetheless, neoepitope load and TILs cytolytic activity are modest in BC, compromising the efficacy of immune-activating antibodies, which do not yet compete against immunogenic chemotherapy.

PATIENTS AND METHODS

We analyzed by functional flow cytometry the immune dynamics of primary and metastatic axillary nodes [metastatic lymph nodes (mLN)] in early BC (EBC) after exposure to T-cell bispecific antibodies (TCB) bridging CD3ε and human epidermal growth factor receptor 2 (HER2) or Carcinoembryonic Antigen-Related Cell Adhesion Molecule 5 (CEACAM5), before and after chemotherapy. Human leukocyte antigen (HLA) class I loss was assessed by whole exome sequencing and immunohistochemistry. One hundred primary BC, 64 surrounding 'healthy tissue' and 24 mLN-related parameters were analyzed.

RESULTS

HLA loss of heterozygosity was observed in EBC, at a clonal and subclonal level and was associated with regulatory T cells and T-cell immunoglobulin and mucin-domain-3 expression restraining the immuno-stimulatory effects of neoadjuvant chemotherapy. TCB bridging CD3ε and HER2 or CEACAM5 could bypass major histocompatibility complex (MHC) class I loss, partially rescuing T-cell functions in mLN.

CONCLUSION

TCB should be developed in BC to circumvent low MHC/peptide complexes.

Metabolic enzymes expressed by cancer cells impact the immune infiltrate

The expression of two metabolic enzymes, i.e., aldehyde dehydrogenase 7 family, member A1 (ALDH7A1) and lipase C, hepatic type (LIPC) by malignant cells, has been measured by immunohistochemical methods in non-small cell lung carcinoma (NSCLC) biopsies, and has been attributed negative and positive prognostic value, respectively. Here, we demonstrate that the protein levels of ALDH7A1 and LIPC correlate with the levels of the corresponding mRNAs. Bioinformatic analyses of gene expression data from 4921 cancer patients revealed that the expression of LIPC positively correlates with abundant tumor infiltration by myeloid and lymphoid cells in NSCLC, breast carcinoma, colorectal cancer and melanoma samples. In contrast, high levels of ALDH7A1 were associated with a paucity of immune effectors within the tumor bed. These data reinforce the notion that the metabolism of cancer cells has a major impact on immune and inflammatory processes in the tumor microenvironment, pointing to hitherto unsuspected intersections between oncometabolism and immunometabolism.

Renal toxicities associated with pembrolizumab

Objective

Expanded clinical experience with patients treated by pembrolizumab has accumulated. However, renal toxicities associated with this anti-programmed cell death 1 agent are poorly described because kidney histology is rarely sought. As a nephrology referral centre, we aimed to describe the clinic-biological and histopathological characteristics of pembrolizumab-related nephropathy and its response to treatment.

Methods

We conducted a monocentric large case series study, including all pembrolizumab-treated cancer patients presenting a renal toxicity addressed to our centre from 2015 to 2017.

Results

A total of 12 patients (7 men) out of 676 pembrolizumab-treated patients (incidence 1.77%) were included (median age 69.75 years). Patients were referred for acute kidney injury (n = 10) and/or proteinuria (n = 2). A kidney biopsy was performed in all patients, with a median duration of use of 9 months (range 1–24 months) after the beginning of treatment. Biopsy showed that four patients had acute interstitial nephritis (AIN), whereas five had acute tubular injury (ATI) alone, one had minimal change disease (MCD) and ATI, and one had MCD alone. Pembrolizumab withdrawal coupled with corticosteroid therapy was the most effective treatment for kidney function recovery. Drug reintroduction resulted in a more severe recurrence of AIN in one patient who required maintenance of pembrolizumab. Two patients died of cancer progression with one of them developing severe renal failure requiring dialysis.

Conclusion

In our series, ATI, AIN and MCD are the most frequent forms of kidney involvement under pembrolizumab therapy. Kidney dysfunction is usually isolated but can be severe. Use of corticosteroids in case of AIN improves the glomerular filtration rate.

Abstract 2597: Development and characterization of novel non-small cell lung cancer (NSCLC) circulating tumor cells (CTCs)-derived xenograft (CDX) models

Background: CDX models are expected to provide crucial information on mechanisms involved in metastatic progression, tumor-initiating properties of CTCs and the development of drug resistance. However, excepted for small-cell lung cancer (SCLC), CDX models are very difficult to develop. Here, we report the establishment, phenotypic and molecular characterization of four NSCLC CDX models and three in vitro cell lines derived from these CDXs.

Methods: CTCs were enriched by RosetteSep from 30 ml blood samples and implanted subcutaneously into Nod/Scid-IL2Rγ-/- (NSG) mice. CDXs were phenotypically and genetically characterized by immunofluorescence, immunohistochemistry and whole-exome sequencing (WES). CDX-derived cell lines were established after mouse fibroblast depletion using classical culture medium. Standard conditions were used for IC50 determination.

Results: Between January 2014 and June 2017, CTCs from 58 NSCLC patients with advanced metastatic disease were implanted into NSG mice resulting in the establishment of four CDXs. All had an epithelial phenotype. Based on CellSearch® counts, median and mean numbers of engrafted CTCs were 9 and 693 respectively (range, 0-17,694). GR-CDXL1, GR-CDXL2, GR-CDXL3, GR-CDXL4 were established starting from 3500, 35, 330, and 1102 CTCs respectively. Measurable tumors were obtained between 100 and 200 days after CTC implantation and were maintained by successive transplantations in NSG mice. Three in-vitro cell lines were established from GR-CDXL1, GR-CDXL3 and GR-CDXL4 tumors, and expressed an epithelial phenotype and CSC-markers such as ALDH, CD133 and CD90. Immunohistochemistry with epithelial and neuroendocrine markers, TTF1 and Ki67 indicated that CDXs and CDX-derived cell lines were representative of the corresponding patient tumor specimens (available in three patients). WES indicated 86%, 93%, 82% mutational similarity between GR-CDXL2, GR-CDXL3 and GR-CDXL4 and the corresponding tumor biopsies. The mutational similarity of GR-CDXL1, GR-CDXL3 and GR-CDXL4 and their corresponding in vitro cell lines was 24%, 83% and 84% respectively. WES of individual CTCs isolated at the time of CTC implantation is ongoing. In in vitro cytotoxicity assays, CDX-derived cell lines mirrored the patient's responsiveness to cisplatin and paclitaxel chemotherapy. The results of ongoing in vivo drug efficacy assays and of mutational tree analyses reconstructing the phylogenic evolution of tumor biopsies, CTCs, CDX and cell lines will be presented.

Conclusion: This study revealed considerable similarities between CDXs and their corresponding patient tumor biopsies. These NSCLC CDX models represent unique tools to identify clonal mutations associated with the tumor-initiating capacity of CTCs and explore the genetic and phenotypic basis of metastasis and drug resistance associated with advanced NSCLC.

Citation Format: Vincent Faugeroux, Emma Pailler, Olivier Deas, Judith Michels, Laura Mezquita, Laura Brulle-Soumare, Stefano Cairo, Jean-Yves Scoazec, Virginie Marty, Pauline Queffelec, Maud Ngo-Camus, Claudio Nicotra, David Planchard, Patricia Kannouche, Benjamin Besse, Jean-Gabriel Judde, Françoise Farace. Development and characterization of novel non-small cell lung cancer (NSCLC) circulating tumor cells (CTCs)-derived xenograft (CDX) models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2597.

Metabolic vulnerability of cisplatin-resistant cancers

Cisplatin is the most widely used chemotherapeutic agent, and resistance of neoplastic cells against this cytoxicant poses a major problem in clinical oncology. Here, we explored potential metabolic vulnerabilities of cisplatin-resistant non-small human cell lung cancer and ovarian cancer cell lines. Cisplatin-resistant clones were more sensitive to killing by nutrient deprivation in vitro and in vivo than their parental cisplatin-sensitive controls. The susceptibility of cisplatin-resistant cells to starvation could be explained by a particularly strong dependence on glutamine. Glutamine depletion was sufficient to restore cisplatin responses of initially cisplatin-resistant clones, and glutamine supplementation rescued cisplatin-resistant clones from starvation-induced death. Mass spectrometric metabolomics and specific interventions on glutamine metabolism revealed that, in cisplatin-resistant cells, glutamine is mostly required for nucleotide biosynthesis rather than for anaplerotic, bioenergetic or redox reactions. As a result, cisplatin-resistant cancers became exquisitely sensitive to treatment with antimetabolites that target nucleoside metabolism.

Multiplex bead-based measurement of humoral immune responses against tumor-associated antigens in stage II melanoma patients of the EORTC18961 trial

Purpose: Determine the prognostic and predictive significance of tumor associated antigen (TAA)-specific serum antibodies in melanoma patients of a large adjuvant vaccination phase III trial. Patients and methods: Serum IgG antibodies were measured against a panel of 43 antigens by a bead-based multiplex assay in 970 stage II melanoma patients of the EORTC18961 trial, evaluating adjuvant ganglioside GM2-KLH/QS-21 vaccination versus observation. Primary end point was relapse-free survival (RFS). Patients' sera at baseline, after 12 and 48 weeks of study treatment and at the last available time point (at recurrence/remission) were evaluated. Results: Prognostic clinical variables are gender, surgical confirmation of lymph node-negative status, Breslow thickness and ulceration of the primary. Prognostic spontaneous antibody responses were associated with a significant dismal (GM2, Rhod_E2, SSX2) or good prognosis (CyclinB1, SCYE1v1) for RFS, distant metastasis-free (DMFS) or overall survival (OS). Predictive spontaneous antibody responses based on significant interaction with treatment were RhodN p = 0.02, Rab38 p = 0.04 for RFS, RhodE2 p = 0.006, Recoverin p = 0.04 for DMFS and RhodE2 p = 0.003; Recoverin p = 0.04, NA17.A p = 0.04, for OS respectively. The subgroups of patients according to antibody responses for RFS were determined for RhodN sero-negative (n = 849, HR = 1.07, p = 0.6); RhodN sero-positive (n = 121,HR = 0.42, p = 0.01) and Rab38 sero-negative (n = 682, HR = 1.12, p = 0.42), Rab38 sero-positive (n = 288, HR = 0.65, p = 0.04) patients respectively. Conclusion: We identified prognostic serum antibody responses against TAA in stage II melanoma patients. A set of antibody responses correlated with a beneficial outcome for GM2 vaccination.

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.

Tumours with class 3 BRAF mutants are sensitive to the inhibition of activated RAS

Approximately 200 BRAF mutant alleles have been identified in human tumours. Activating BRAF mutants cause feedback inhibition of GTP-bound RAS, are RAS-independent and signal either as active monomers (class 1) or constitutively active dimers (class 2). Here we characterize a third class of BRAF mutants-those that have impaired kinase activity or are kinase-dead. These mutants are sensitive to ERK-mediated feedback and their activation of signalling is RAS-dependent. The mutants bind more tightly than wild-type BRAF to RAS-GTP, and their binding to and activation of wild-type CRAF is enhanced, leading to increased ERK signalling. The model suggests that dysregulation of signalling by these mutants in tumours requires coexistent mechanisms for maintaining RAS activation despite ERK-dependent feedback. Consistent with this hypothesis, melanomas with these class 3 BRAF mutations also harbour RAS mutations or NF1 deletions. By contrast, in lung and colorectal cancers with class 3 BRAF mutants, RAS is typically activated by receptor tyrosine kinase signalling. These tumours are sensitive to the inhibition of RAS activation by inhibitors of receptor tyrosine kinases. We have thus defined three distinct functional classes of BRAF mutants in human tumours. The mutants activate ERK signalling by different mechanisms that dictate their sensitivity to therapeutic inhibitors of the pathway.

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.

Predicting and preventing thromboembolic events in patients receiving cisplatin-based chemotherapy for germ cell tumours

BACKGROUND

Patients with germ cell tumours (GCT) receiving cisplatin-based chemotherapy are at high risk of thromboembolic events (TEE). Previously, we identified serum lactate dehydrogenase (LDH) and body surface area (BSA) as independent predictive factors for TEE. The aim of this study was to validate these predictive factors and to assess the impact of thromboembolism prophylaxis in patients at risk of deep venous thrombosis (DVT).

METHODS

Between 2001 and 2014, 295 patients received first-line cisplatin-based chemotherapy for GCT. Preventive anticoagulation with low-molecular-weight heparin (LMWH) was progressively implemented in patients with predictive factors. Sixteen patients with evidence of TEE before starting chemotherapy were excluded from the analysis.

RESULTS

Among 279 eligible patients, a TEE occurred in 38 (14%) consisting of DVT (n = 26), arterial thrombosis (n = 2), and superficial thrombophlebitis (n = 10). DVT occurred in 26 (12.7%) of 204 patients with risk factors versus two (2.6%) of 75 patients with no risk factors (p = 0.01). After a prevention protocol was progressively implemented from 2005, primary thromboprophylaxis was administered to 104 patients (68%) with risk factors. Among patients at risk (n = 151), the incidence of DVT decreased by roughly half when they received a LMWH: 9/97 (9.2%) and 9/54 (16.6%), respectively (p = 0.23).

CONCLUSION

Patients with GCT who receive cisplatin-based chemotherapy are at risk of developing a TEE which can be predicted by elevated serum LDH. To our knowledge this is the first study exploring LMWH as thromboprophylaxis in GCT patients. A prospective trial testing prophylactic anticoagulation is warranted.

Abstract 2256: Establishment and characterization of circulating tumor cell-derived xenografts in non-small cell lung cancer

Low numbers of circulating tumor cells (CTCs) have so far limited the establishment of CTC-derived xenografts (CDXs) to improve our understanding of tumor progression, drug resistance mechanisms, and their biological properties. We report the establishment and the phenotypic and molecular characterization of one NSCLC CDX.

Blood samples (30 ml) were drawn from 49 NSCLC patients with advanced metastatic disease. CTCs were enriched by RosetteSep, embedded in matrigel, and implanted in the interscapular aspect of NSG mouse (Nod/Scid-IL2Rγ-/-). Mice were followed-up for one year according to ethical regulations. CDX tumours and CDX derived cell lines were phenotypically and molecularly characterized by immunofluorescence, immunohistochemistry, CGHarray, exome sequencing and transcriptome gene expression.

CTCs from one NSCLC patient with 750 CTCs detected by CellSearch gave rise to a tumor 5 months after initial murine injection. Histological analysis confirmed the human origin of the tumor and the presence of a poorly differentiated adenocarcinoma consistent with the patient's biopsy. Tumor was positive for EpCAM, EMA, CK8;18, and Ki67, and negative for vimentin. A fraction of cells (25%) from freshly dissociated tumors exhibited ALDH activity. CGH from CDX tumors at passage 1 and 2 shows multiple gene rearrangement, revealing a high degree of genomic instability. Transcriptome analysis of ALDH positive and negative cells is ongoing and should help of identifying a cancer stem cell gene expression signature. Whole-exome sequencing of CDX tumor is ongoing and will be compared to data obtained from single CTCs from the patient.

A cell line established in vitro from the CDX model grows in 3D clusters and is tumorigenic in mice. Interestingly, this cell line is positive for cytokeratins, EpCAM, E-cadherin, N-cadherin, vimentin, and expresses multiple cancer stem cell markers including CD166, CD24, CD133 and, ALDH activity. The cell line is hypotetraploid (about 70 chromosomes) and its CGH profile was similar to that of the CDX tumour, revealing a high level of genome instability. By investigating DNA replication process in this cell line, we found that it exhibits a spontaneous enhanced DNA damage signaling associated to an accumulation of DNA double strand breaks mainly in S phase strongly suggesting that the CDX-derived cell line displays hallmarks on replication stress that could explain, at least partially, the genomic instability in the cells.

We report a low success rate in the establishment of NSCLC CDX (2%). However one NSCLC CDX model harboring cancer stem cell properties and deficiency of DNA replication maintenance was established. Ongoing work to identify a cancer stem cell signature and characteristics replication stress markers in this CDX model will be presented. This NSCLC CDX model will be useful to test drugs targeting these alterations in vivo and improve our knowledge of drug resistance.

Citation Format: Vincent Faugeroux, Olivier Deas, Judith Michels, Jean Gabriel Judde, Stefano Cairo, Philippe Vielh, Virginie Marty, Fanny Billiot, Maud Ngocamus, Benjamin Besse, Patricia Kannouche, Françoise Farace. Establishment and characterization of circulating tumor cell-derived xenografts in non-small cell lung cancer. [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 2256.

Calreticulin expression: Interaction with the immune infiltrate and impact on survival in patients with ovarian and non-small cell lung cancer

Loss of expression of calreticulin (CALR) has been detected by immunohistochemistry in a fraction of non-small cell lung cancers (NSCLC) and has been demonstrated to have a major negative prognostic impact on overall patient survival. Here, we analyzed the impact of CALR expression levels detected by microarray finding a positive correlation between CALR and the expression of a metagene indicating the presence of cytotoxic T lymphocytes (CTL) in NSCLC and ovarian cancer. In addition, we detected a positive correlation with a metagene suggestive of activated dendritic cell (aDC) infiltration in ovarian cancer. Combination of two parameters (CALR + DC (dendritic cell) in NSCL and CALR + aDC in ovarian cancer) or three parameters (CALR + CTL + DC in NSCL and CALR + CTL + aDC in ovarian cancer) had a significant impact on overall patient survival in NSCL (Adenoconsortium) and ovarian cancer (TCGA collection), allowing the stratification of patients in high-risk and low-risk groups. In addition, CALR and aDC alone have a significant impact on overall survival in ovarian cancer. In contrast, in mammary, colorectal and prostate cancer, CALR had no impact on patient survival if analyzed alone or in combination with the immune infiltrate. In addition, CALR correlates with CTL infiltrate in three cancer types (colorectal, breast, ovarian). Altogether, these results support the contention that, at least in some cancers, loss of CALR expression may negatively affect immunosurveillance, thereby reducing patient survival.

Prime time for immune-checkpoint targeted therapy at ASCO 2015

Cancer immunotherapy has been one of the dominant topics in oral presentations and abstracts during the 2015 annual meeting of the American Society of Clinical Oncology (ASCO). The renewed interest in immunotherapy is explained by the wide spectrum of activity, the durability of tumor responses and the rapid clinical development of immune-checkpoint targeted monoclonal antibodies. These new drugs are currently revolutionizing the field of oncology. Here we highlight what were to us the most important results announced during the annual meeting of ASCO held in Chicago, IL from May, 29th to June, 2nd 2015. In addition, we searched all the posters/published abstracts pertinent to the field of immunooncology from this year conference. Among more than 400 published abstracts on this topic, we have grouped and briefly summarized the most relevant ones.

Negative prognostic value of high levels of intracellular poly(ADP-ribose) in non-small cell lung cancer

BACKGROUND

Cisplatin-resistant non-small cell lung cancer (NSCLC) cells are often characterized by alterations in vitamin B-related metabolic processes, including the overexpression and hyperactivation of poly(ADP-ribose) polymerase 1 (PARP1) and the downregulation of pyridoxal kinase (PDXK), correlating with elevated apoptosis resistance. Low PDXK expression is an established negative prognostic factor in NSCLC.

PATIENTS AND METHODS

We determined by immunohistochemistry the expression of PARP1 and the level of its product, poly(ADP-ribose) (PAR), in two independent cohorts of patients with resected NSCLC.

RESULTS

Intratumoral high levels (above median) of PAR (but not PARP1 protein levels) had a negative prognostic impact in both the training (92 stage I subjects) and validation (133 stage I and II subjects) cohorts, as determined by univariate and multivariate analyses. The simultaneous assessment of PAR and PDXK protein levels improved risk stratification.

CONCLUSION

NSCLC patients with high intratumoral PARP1 activity (i.e. elevated PAR levels above median) and low PDXK expression (below median) had a dismal prognosis, while patients with low PARP1 activity and high PDXK expression had a favorable outcome. Altogether, these results underscore the clinical potential and possible therapeutic relevance of these biomarkers.

Abstract 4691: Overactivation of poly (ADP-ribose) polymerase (PARP) in localised non-small cell lung cancer (NSCLC) predicts dismal prognosis

Recent studies underscore the general cytoprotective role of PARP1 and PAR in response to multiple extrinsic and intrinsic stress signals. Moreover, elevated levels of PARP have been correlated with increased tumor aggressiveness in breast cancer. Based on these premises, we decided to test whether PARP/PAR levels would be associated with prognosis in a cohort of localised NSCLC patients. Our cohort of patients underwent surgery from 1994 to 2002 and did not receive any chemotherapy. In these tumors, expression of PARP enzyme and the presence of its product, PAR, exhibited a significant, though not absolute, correlation, as determined by immunohistochemistry. The staining of PAR and PARP was almost exclusively nuclear, though highly variable in its intensity. Ninety-two NSCLC specimens were scored on a continuous scale of 0-300 and patients were stratified (separated by the median) into PAR low, PAR high, PARP low and PARP high groups. Tumor-infiltrating lymphocytes (which manifest high PARP and PAR levels) were used as an internal positive control of the staining procedure. Of note, among PARP low tumors, 32.5% were PAR high, indicating that low PARP protein levels do not preclude a high enzymatic activity. While high PAR levels had a significant negative impact on both disease-free (DFS) and overall survival (OS) (p=0.02 and 0.01, in univariate and 0.07 and 0.04 in multivariate analysis respectively), PARP expression did not correlate with either of these outcomes. We could validate PAR as a negative prognostic biomarker in a second cohort of 136 patients operated from 2002 to 2006. Altogether, these results identify high PAR levels as a biomarker of dismal prognosis in NSCLC.

Citation Format: Judith Michels, Aïcha Goubar, Julien Adam, Lorenzo Galluzzi, Ken André Olaussen, Angélique Robin, Philippe Girard, Isabelle Kremer, Maria Castedo, Jean-Charles Soria, Guido Kroemer. Overactivation of poly (ADP-ribose) polymerase (PARP) in localised non-small cell lung cancer (NSCLC) predicts dismal prognosis. [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 4691. doi:10.1158/1538-7445.AM2014-4691

PARP and other prospective targets for poisoning cancer cell metabolism

Increasing evidence indicates that cancer cells rewire their metabolism during tumorigenesis. The high intracellular levels of lactate and reactive oxygen species (ROS) generated during enhanced aerobic glycolysis and mitochondrial oxidative phosphorylation respectively led to oxidative stress. The detoxification of these accumulating metabolites and the equilibrium between reduced and oxidized nicotine adenine dinucleotide (NADH and NAD(+)) are two prominent mechanisms regulating redox status and hence energy homeostasis in tumors. Targeting both processes may thus be selectively cytotoxic for cancer cells. In this context, the impact of poly(ADP-ribose) polymerase (PARP) inhibitors, a class of anticancer agents employed for the treatment of DNA repair deficient tumors, on energy homeostasis and mitochondrial respiration regulation has potential clinical implications. Here we provide an overview of the metabolic reprogramming occurring in cancer cells and discuss the translational perspectives of targeting tumor metabolism and redox balance for antineoplastic therapy.

MCL-1 dependency of cisplatin-resistant cancer cells

The selection of human cancer cell lines in cis-diamminedichloroplatinum(II) (CDDP, best known as cisplatin) is accompanied by stereotyped alterations that contribute to the acquisition of a CDDP-resistant state. Thus, CDDP resistance often leads to the upregulation of the DNA repair enzyme poly (ADP-ribose) polymerase-1 (PARP1) with the consequent intracellular accumulation of poly (ADP-ribose) (PAR)-modified proteins. Here we report another frequent alteration accompanying CDDP resistance, namely upregulation of the antiapoptotic BCL-2 family protein MCL-1. Six out of 8 CDDP resistant cancer cell lines manifested an increase in MCL-1 protein expression level, while only a minority of cell lines overexpressed BCL-2 or BCL-XL. BCL-XL was decreased in six out of 8 cancer cell lines. Importantly, MCL-1 overexpressing, CDDP resistant cells appear to be 'addicted' to MCL-1 because they died upon depletion of MCL-1 by RNA interference or pharmacological inhibition of MCL-1 expression by the BH3 mimetic obatoclax. Knockdown of PARP1 did not succeed in reducing MCL-1 expression, while depletion or inhibition of MCL-1 failed to affect the activity of PARP1. Hence, the two resistance mechanisms are not linked to each other by a direct cause-effect relationship. Importantly, CDDP-resistant, MCL-1 overexpressing human non-small cell lung cancers responded to monotherapy with obatoclax in vivo, in xenotransplanted mice, underscoring the probable therapeutic relevance of these findings.