Randomized multicenter phase II trial comparing two schedules of etirinotecan pegol (NKTR-102) in women with recurrent platinum-resistant/refractory epithelial ovarian cancer

Integration of single-cell RNA-seq and bulk RNA-seq data to construct and validate a cancer-associated fibroblast-related prognostic signature for patients with ovarian cancer

BACKGROUND

To establish a prognostic risk profile for ovarian cancer (OC) patients based on cancer-associated fibroblasts (CAFs) and gain a comprehensive understanding of their role in OC progression, prognosis, and therapeutic efficacy.

METHODS

Data on OC single-cell RNA sequencing (scRNA-seq) and total RNA-seq were collected from the GEO and TCGA databases. Seurat R program was used to analyze scRNA-seq data and identify CAFs clusters corresponding to CAFs markers. Differential expression analysis was performed on the TCGA dataset to identify prognostic genes. A CAF-associated risk signature was designed using Lasso regression and combined with clinicopathological variables to develop a nomogram. Functional enrichment and the immune landscape were also analyzed.

RESULTS

Five CAFs clusters were identified in OC using scRNA-seq data, and 2 were significantly associated with OC prognosis. Seven genes were selected to develop a CAF-based risk signature, primarily associated with 28 pathways. The signature was a key independent predictor of OC prognosis and relevant in predicting the results of immunotherapy interventions. A novel nomogram combining CAF-based risk and disease stage was developed to predict OC prognosis.

CONCLUSION

The study highlights the importance of CAFs in OC progression and suggests potential for innovative treatment strategies. A CAF-based risk signature provides a highly accurate prediction of the prognosis of OC patients, and the developed nomogram shows promising results in predicting the OC prognosis.

A polyethylene glycol-conjugate of deoxycytidine analog, DFP-14927, produces potential antitumor effects on pancreatic tumor-xenograft murine models via inducing G2/M arrest

A deoxycytidine analog is a potential agent for the treatment of several cancers, which includes poorly prognostic pancreatic cancer. We previously developed deoxycytidine analog DFP-10917, and long-term/low-dose infusions of this analog has produced antitumor effects in leukemia cancer- and ovarian cancer-xenograft models. DFP-10917 is now undergoing clinical Phase III study in the United States for the treatment of patients with relapsed or refractory acute myeloid leukemia. PEG-drug conjugation has become a promising technique to improve the pharmacokinetic and pharmacodynamic properties of anti-cancer drugs. In the present study, we synthesized a novel PEG-drug conjugate of DFP-10917, referred to hereafter as DFP-14927, using a 4-armed CTPEG system to endow the DFP-10917 drug with favorable long-circulating properties that maximize its utility and antitumor efficacy. Intravenous injection of the synthesized DFP-14927 returned encouraging antitumor effects in a Panc-1 human pancreatic tumor- and a BxPC-3 human pancreatic tumor-xenograft models. These effects were comparable to that of free DFP-10917 as well as to that of gemcitabine, which is considered a standard in the treatment of pancreatic cancer. In vitro studies revealed that DFP-14927 inhibits cell division on human pancreatic cancer cell lines via arrest of the G2/M phase in the cell cycle, which is consistent with the effects of free DFP-10917. Intravenous administration of the newly synthesized DFP-14927 has induced G2/M arrest in human pancreatic tumor-xenograft murine models, which represents an improvement in the pharmacokinetics of DFP-10917. DFP-14927 could be an alternative for patients who cannot accept prolonged or continuous infusions of DFP-10917.

Endogenous Propionibacterium acnes Promotes Ovarian Cancer Progression via Regulating Hedgehog Signalling Pathway

BACKGROUND

The oncogenesis and progression of epithelial ovarian cancer (EOC) is a complicated process involving several key molecules and factors, yet whether microbiota are present in EOC, and their role in the development of EOC, remains greatly unknown.

METHODS

In this study, 30 patients were enrolled to compare the similarities and differences of intratumour microbiota among patients with epithelial benign ovarian tumours (EBOTs) and patients with EOC based on the high-throughput sequencing method. Subsequently, we further isolated the specific EOC-related bacteria and defined Propionibacterium acnes as a key strain in facilitating EOC progression. More importantly, we constructed a mouse EOC model to evaluate the effect of the P. acnes strain on EOC using immunohistochemistry, Western blotting, and RT-qPCR.

RESULTS

The high-throughput sequencing showed that the intratumour microbiota in EOC tissues had a higher microbial diversity and richness compared to EBOT tissues. The abundance of previously considered pathogens, Actinomycetales, Acinetobacter, Streptococcus, Ochrobacterium, and Pseudomonadaceae Pseudomonas, was increased in the EOC tissues. Meanwhile, we discovered the facilitating role of the P. acnes strain in the progression of EOC, which may be partially associated with the increased inflammatory response to activate the hedgehog (Hh) signalling pathway. This microbial-induced EOC progression mechanism is further confirmed using the inhibitor GANT61.

CONCLUSIONS

This study profiled the intratumour microbiota of EBOT and EOC tissues and demonstrated that the diversity and composition of the intratumour microbiota were significantly different. Furthermore, through in vivo and in vitro experiments, we confirmed the molecular mechanism of intratumour microbiota promotion of EOC progression in mice, which induces inflammation to activate the Hh signalling pathway. This could provide us clues for improving EOC treatment.

Impact of Value Frameworks on the Magnitude of Clinical Benefit: Evaluating a Decade of Randomized Trials for Systemic Therapy in Solid Malignancies

In the era of rapid development of new, expensive cancer therapies, value frameworks have been developed to quantify clinical benefit (CB). We assessed the evolution of CB since the 2015 introduction of The American Society of Clinical Oncology and The European Society of Medical Oncology value frameworks. Randomized clinical trials (RCTs) assessing systemic therapies for solid malignancies from 2010 to 2020 were evaluated and CB (Δ) in 2010–2014 (pre-value frameworks (PRE)) were compared to 2015–2020 (POST) for overall survival (OS), progression-free survival (PFS), response rate (RR), and quality of life (QoL). In the 485 studies analyzed (12% PRE and 88% POST), the most common primary endpoint was PFS (49%), followed by OS (20%), RR (12%), and QoL (6%), with a significant increase in OS and decrease in RR as primary endpoints in the POST era (p = 0.011). Multivariable analyses revealed significant improvement in ΔOS POST (OR 2.86, 95% CI 0.46 to 5.26, p = 0.02) while controlling for other variables. After the development of value frameworks, median ΔOS improved minimally. The impact of value frameworks has yet to be fully realized in RCTs. Efforts to include endpoints shown to impact value, such as QoL, into clinical trials are warranted.

Adverse Effects and Safety of Etirinotecan Pegol, a Novel Topoisomerase Inhibitor, in Cancer Treatment: A Systematic Review

Background:

Due to the increasing prevalence of cancer and the inadequacy of current therapies, the development of novel antitumor pharmaceutics with higher efficacies and lower adverse effects is considered a fundamental tenet of contemporary cancer management. Poly-Ethylene-Glycol (PEG) attachment is a novel pharmaceutical technology to improve the efficacy and safety of chemotherapies. Etirinotecan Pegol (EP), also known as NKTR-102, is the PEGylated form of Irinotecan (CPT-11), which causes cancer cell apoptosis by inhibiting the topoisomerase I enzyme.

Objectives:

The present study reviews and evaluates various reports of the EP’s anti-tumor activity in various cancers.

Data Sources:

Studies were identified using the Scopus database, with no exclusions. The search terms included Etirinotecan Pegol and NKTR-102, which yielded 125 articles (66 and 59 articles, respectively). In addition, the clinicaltrials.gov website was used to find ongoing studies, which resulted in the addition of two studies.

Study Eligibility Criteria:

Subsequently, we excluded studies that were published in languages other than English, duplicate articles, and studies with no data.

Results:

This systematic review clarifies that EP possesses numerous advantages over many other medications, such as safety, efficacy, increased half-life, increased health-related quality of life, increased overall survival, increased progression-free survival, and decreasing the adverse events in the treatment of various cancers.

Conclusion:

Therefore, Etirinotecan Pegol may represent a major contribution to the treatment of various cancers in the future.

A novel polyethylene glycol (PEG)-drug conjugate of Venetoclax, a Bcl-2 inhibitor, for treatment of acute myeloid leukemia (AML)

Background

Venetoclax (VTX) is an anticancer drug. It is a selective Bcl‐2 inhibitor that is clinically used for the treatment of patients with lymphomas and leukemias. Treatment with VTX, however, is accompanied by severe adverse events such as tumor lysis syndrome and neutropenia, because VTX readily binds to serum proteins, which results in poor pharmacokinetics and poor tumor tissue concentration. To avoid such adverse events, VTX is administered using a daily or weekly ramp‐up schedule that is cumbersome in clinical situations.

Aims

To overcome these shortcomings, we prepared a novel polyethylene glycol (PEG)‐drug conjugate of VTX (PEG‐VTX) and evaluated its cytotoxic effects on acute myeloid leukemia (AML) both in vitro and in vivo.

Methods and results

VTX and 4‐armed PEG derivatives were covalently attached through an amide bond linker. In a series of in vitro studies, PEG‐VTX selectively induced potent growth inhibition of MV4‐11 human AML cells via the inducement of Bcl‐2‐mediated apoptosis. PEG‐VTX had the effect of free VTX, presumably due to the protease‐mediated release of VTX from the conjugates. In in vivo studies with AML tumor‐xenograft mice models, intravenous PEG‐VTX promoted sufficient tumor growth suppression. Compared with a regimen of oral free VTX, the intravenous regimen in those studies used a VTX dosage that was 15–30 times smaller for an OCI‐AML‐2 xenograft model and a dosing regimen that was less frequent for an MV4‐11 xenograft model. The most important development, however, was the absence of weight loss related to severe side effects throughout the treatments. An increase in water solubility and the resultant hydrodynamic size of VTX via PEGylation improved the pharmacokinetics of VTX by avoiding protein interactions and lessening the extravasation from blood. The result was an increase in tumor accumulation and a decrease in the nonspecific distribution of VTX.

Conclusion

The results of this study suggest that PEG‐VTX could be an alternative therapeutic option for the safe and effective treatment of patients with AML.

Vitamin C Inhibits Metastasis of Peritoneal Tumors By Preventing Spheroid Formation in ID8 Murine Epithelial Peritoneal Cancer Model

High mortality is associated with exclusively metastasis within the peritoneal cavity among patients with epithelial ovarian cancer that is the most lethal gynecologic cancer. There is an unmet need to develop more effective therapies to prevent metastasis of peritoneal cancer. Multicellular spheroid formation, during which cancer cells migrate and adhere to tumor-associated macrophages, is a critical step of ovarian cancer metastasis. Here, we showed that vitamin C inhibited spheroid formation and metastasis in ID8 ovarian cancer-bearing mice. We further found that vitamin C treatment decreased the levels of M2 macrophages in tumor nodules and suppressed the epithelial-mesenchymal transition (EMT). In vitro studies revealed that vitamin C inhibited proliferation, arrested cell cycle, attenuated migration, and prevented the spheroid formation of ID8 ovarian cancer cells. Vitamin C induced apoptosis of ID8 cells, which was confirmed by membrane potential collapse, cytosolic calcium overload, ATP depletion, and caspase-3 activation in vitamin C-treated cells. Intriguingly, vitamin C treatment caused striking morphological change and apoptosis of macrophages. The presented proof of concept study strategically identifies new anticancer mechanisms of vitamin C.

Clinical developments of antitumor polymer therapeutics

Polymer therapeutics encompasses polymer-drug conjugates that are nano-sized, multicomponent constructs already in the clinic as antitumor compounds, either as single agents or in combination with other organic drug scaffolds. Nanoparticle-based polymer-conjugated therapeutics are poised to become a leading delivery strategy for cancer treatments as they exhibit prolonged half-life, higher stability and selectivity, water solubility, longer clearance time, lower immunogenicity and antigenicity and often also specific targeting to tissues or cells. Compared to free drugs, polymer-tethered drugs preferentially accumulate in the tumor sites unlike conventional chemotherapy which does not discriminate between the cancer cells and healthy cells, thereby causing severe side-effects. It is also desirable that the drug reaches its site of action at a particular concentration and the therapeutic dose remains constant over a sufficiently long period of time. This can be achieved by opting for new formulations possessing polymeric systems of drug carriers. However, many challenges still remain unanswered in polymeric drug conjugates which need to be readdressed and therefore, can broaden the scope of this field. This review highlights some of the antitumor polymer therapeutics including polymer-drug conjugates, polymeric micelles, polymeric liposomes and other polymeric nanoparticles that are currently under investigation.

Etirinotecan pegol in women with recurrent platinum-resistant or refractory ovarian cancer

Introduction: A PEGylated form of irinotecan, a topoisomerase I inhibitor, is now available in commerce; its safety and efficacy have been tested in platinum resistant/refractory ovarian cancer (PROC) patients. This novel agent is known as Etirinotecan Pegol (EP). EP, like irinotecan, exerts its action through its principal metabolite SN-38. Areas covered: This drug evaluation article focuses on the most recent investigations and clinical progress regarding EP, a long-acting polymer conjugate of irinotecan for the treatment of PROC. Expert opinion: EP provides prolonged and continuous exposure of SN-38 in tumors, when compared to its parent drug irinotecan. Results from phase II studies are comparable in terms of efficacy to other agents of proven use in PROC. A limitation of the use of EP is the schedule-dependent toxicities (mainly diarrhea and dehydration). In the future, EP could be investigated in association with other agents, even in attempts to restore sensitivity to other treatments. PROC remains a very difficult setting and EP might be a valid agent for patients with good performance status that have exhausted therapeutic options. In such a setting, participation in clinical trials is strongly encouraged.

Emerging PEGylated non-biologic drugs

Introduction: PEGylation is a well-established technology for improving the therapeutic value of drugs by attaching polyethylene glycol (PEG). The first PEGylated enzyme products appeared on the market in the early 1990s; currently, more than 18 PEGylated products have been approved by Food and Drug Administration, which encompass various classes of drug molecules, such as enzymes, interferons, granulocyte colony-stimulating factors, hormones, antibody fragments, coagulation factors, oligonucleotide aptamers, synthetic peptides, and small organic molecules. Areas covered: While PEGylated products mainly comprise biologic drugs, such as recombinant proteins and enzymes, non-biologic drugs have recently emerged as a target for PEGylation. This review focuses on the recent development of PEGylated non-biologic drugs, such as small organic molecules, synthetic peptides, and aptamers. Expert opinion: Several PEGylated versions of anti-cancer drugs, opioid agonists, glucagon-like peptide-1 receptor agonists, and oligonucleotide aptamers are in active development stage, and it is likely that they will have a dramatic impact on the market. Although some safety concerns about PEG in clinical trials have been recently issued, PEGylation is still a commercially attractive proposition as a half-life extension technology for long-acting drug development.

Targeted delivery of chemotherapy using HSP90 inhibitor drug conjugates is highly active against pancreatic cancer models

The lack of effective treatment modalities is a major problem in pancreatic cancer (PCa), a devastating malignancy that is nearly universally driven by the “undruggable” KRAS and TP53 cancer genes. Poor tumor tissue penetration is the major source of resistance in pancreatic cancer where chemotherapy is the mainstay of treatment. In this study we exploited the selective tumor-targeting properties of the heat shock 90 protein inhibitors as the vehicle for drug delivery to pancreatic tumor tissues. STA-12-8666 is a novel esterase-cleavable conjugate of an HSP90i and a topoisomerase I inhibitor, SN-38. STA-12-8666 selectively binds activated HSP90 and releases its cytotoxic payload resulting in drug accumulation in pancreatic cancer cells in vivo. We investigated the preclinical activity of STA-12-8666 in patient derived xenograft and genetic models of pancreatic cancer.

Treatment with STA-12-8666 of the KPC mice (knock-in alleles of LSL-Kras^G12D, Tp53^fl/fl and Pdx1-Cre transgene) at the advanced stages of pancreatic tumors doubled their survival (49 days vs. 74 days, p=0.008). STA-12-8666 also demonstrated dramatically superior activity in comparison to equimolar doses of irinotecan against 5 patient-derived pancreatic adenocarcinoma xenografts with prolonged remissions in some tumors. Analysis of activity of STA-12-8666 against tumor tissues and matched cell lines demonstrated prolonged accumulation and release of cytotoxic payload in the tumor leading to DNA damage response and cell cycle arrest.

Our results provide a proof-of-principle validation that HSP90i-based drug conjugates can overcome the notorious treatment resistance by utilizing the inherently high affinity of pancreatic cancer cells to HSP90 antagonists.

Systemic therapy for recurrent epithelial ovarian cancer: a clinical practice guideline

Objective

The purpose of this guideline is to recommend systemic therapy options for women with recurrent epithelial ovarian cancer, including fallopian tube and primary peritoneal cancers.

Methods

This document updates the recommendations published in the 2011 Optimal Chemotherapy for Recurrent Ovarian Cancer guideline from Cancer Care Ontario. Draft recommendations were formulated based on evidence obtained through a systematic review of phase ii and iii randomized controlled trials (rcts). The draft recommendations underwent internal review by clinical and methodology experts, and external review by clinical practitioners through a survey assessing the clinical relevance and overall quality of the guideline. Feedback from the internal and external reviews was integrated into the clinical practice guideline.

Results

The primary literature search yielded thirty-six primary research papers representing thirty rcts that met the eligibility criteria. The guideline provides recommendations for patients with serous tumour histologies and with recurrent, platinum-resistant, and platinum-sensitive ovarian cancer.

Conclusions

The body of evidence from trials that included olaparib and bevacizumab consistently shows a benefit in progression-free survival (pfs) without a corresponding benefit in overall survival (os). The Working Group for this guideline designated pfs, which is associated with symptom control, as a critical outcome. A finding of net benefit can therefore be concluded based on significant differences in pfs. However, that benefit is not without identified harms. Given the identified harms, patient involvement in the decision-making process must take into consideration the side effect profiles of olaparib and bevacizumab within the context of improved pfs but minimal change in os.

Selective and Concentrated Accretion of SN-38 with a CEACAM5-Targeting Antibody-Drug Conjugate (ADC), Labetuzumab Govitecan (IMMU-130)

Labetuzumab govitecan (IMMU-130), an antibody-drug conjugate (ADC) with an average of 7.6 SN-38/IgG, was evaluated for its potential to enhance delivery of SN-38 to human colonic tumor xenografts. Mice bearing LS174T or GW-39 human colonic tumor xenografts were injected with irinotecan or IMMU-130 (SN-38 equivalents ∼500 or ∼16 μg, respectively). Serum and homogenates of tumors, liver, and small intestine were extracted, and SN-38, SN-38G (glucuronidated SN-38), and irinotecan concentrations determined by reversed-phase HPLC. Irinotecan cleared quickly from serum, with only 1% to 2% injected dose/mL after 5 minutes; overall, approximately 20% was converted to SN-38 and SN-38G. At 1 hour with IMMU-130, 45% to 63% injected dose/mL of the SN-38 was in the serum, with >90% bound to the ADC over 3 days, and with low levels of SN-38G. Total SN-38 levels decreased more quickly than the IgG, confirming a gradual SN-38 release from the ADC. AUC analysis found that SN-38 levels were approximately 11- and 16-fold higher in LS174T and GW-39 tumors, respectively, in IMMU-130-treated animals. This delivery advantage is amplified >30-fold when normalized to SN-38 equivalents injected for each product. Levels of SN-38 and SN-38G were appreciably lower in the liver and small intestinal contents in animals given IMMU-130. On the basis of the SN-38 equivalents administered, IMMU-130 potentially delivers >300-fold more SN-38 to CEA-producing tumors compared with irinotecan, while also reducing levels of SN-38 and SN-38G in normal tissues. These observations are consistent with preclinical and clinical data showing efficacy and improved safety. Mol Cancer Ther; 17(1); 196-203. ©2017 AACR.

Randomized study of etirinotecan pegol versus irinotecan as second-line treatment for metastatic colorectal cancer

PURPOSE

Etirinotecan pegol (EP) is a long-acting topoisomerase-I inhibitor designed to provide sustained exposure to SN-38 (active metabolite of irinotecan). This phase II study compared EP versus irinotecan as second-line treatment for KRAS-mutant, irinotecan-naïve, metastatic colorectal cancer (mCRC).

METHODS

Patients were randomized to EP 145 mg/m² or irinotecan 350 mg/m² Q21d until disease progression/unacceptable toxicity. The primary endpoint was progression-free survival (PFS) with response determined by central radiologic review (RECIST version 1.1).

RESULTS

The study was terminated before completing accrual due to evolving standards of care. Eighty-three patients were randomized. Median PFS was longer with EP versus irinotecan (4.0 versus 2.8 months, respectively; HR 0.65; 95% CI 0.40-1.04; P = 0.07). Six-month PFS rates were 32.8 and 15.4%, respectively. Median OS was 9.6 and 8.4 months in EP and irinotecan arms, respectively (HR 0.91; 95% CI 0.56-1.49). ORRs were 10 and 5%, respectively (P = 0.676); median DOR was significantly longer in EP arm (7.9 versus 1.4 months; P = 0.018). The most common grade-3/4 adverse events for EP and irinotecan were diarrhea (21 vs 20%), neutropenia (10 vs 22%), abdominal pain (14 vs 5%), nausea (14 vs 2%), and vomiting (12 vs 7%), respectively.

CONCLUSION

EP is active and safe for second-line treatment of KRAS-mutant, irinotecan-naïve mCRC.

Etirinotecan Pegol (NKTR-102) in Third-line Treatment of Patients With Metastatic or Recurrent Non-Small-cell Lung Cancer: Results of a Phase II Study

BACKGROUND

Third-line treatment options are limited for patients with metastatic non-small-cell lung cancer (NSCLC). Etirinotecan pegol (NKTR-102) is a long-acting topoisomerase-I inhibitor. We conducted a single-arm phase II trial to evaluate its efficacy in third-line treatment.

PATIENTS AND METHODS

Patients aged ≥ 18 years with histologically proven NSCLC who had received 2 previous systemic therapy regimens, measurable disease, Eastern Cooperative Oncology Group (ECOG) performance status ≤ 1, and adequate end-organ function were eligible. Etirinotecan pegol was administered at a dose of 145 mg/m² intravenously once every 3 weeks until progression. The response was assessed every 6 weeks using Response Evaluation Criteria In Solid Tumors, version 1.1. The primary endpoint was the overall objective response rate. The secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. A Simon 2-stage design was implemented for futility.

RESULTS

From January 2013 to January 2015, 40 patients were enrolled. Their median age was 66 years (range, 19-85 years), 45% were female, 30% had an ECOG performance status of 0, 96% were current and former smokers, and 31 had adenocarcinoma. Patients received a median of 3 cycles (range, 2-15) of protocol therapy. The best response was a partial response in 2 patients. The treatment was well tolerated; 3 patients had grade 3 gastrointestinal toxicity attributable to therapy. The median PFS was 2.3 months (95% confidence interval [CI], 1.3-4.4 months), and the median OS was 7.1 months (95% CI 4.2-11.4 months).

CONCLUSIONS

Etirinotecan pegol was well tolerated and led to 2 partial responses and disease stabilization with this third-line treatment of metastatic NSCLC. However, the study failed to meet its prespecified response rate endpoint.

A multicenter, open-label, expanded phase 2 study to evaluate the safety and efficacy of etirinotecan pegol, a polymer conjugate of irinotecan, in women with recurrent platinum-resistant or refractory ovarian cancer

OBJECTIVE

Etirinotecan pegol (EP) is a novel polyethylene glycol conjugated form of irinotecan with documented activity in platinum-resistant ovarian cancer (PROC). We report the results of the expanded portion of a phase II study of EP in patients with PROC who received prior pegylated liposomal doxorubicin (PLD) or who were unable to receive it.

METHODS

This multicenter, open-label, phase II study evaluated EP q21d for PROC. The primary endpoint was objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors version 1.0. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. Patient populations evaluated included a modified intent-to-treat (mITT) group consisting of all patients who received at least one dose and with measurable disease and a primary efficacy (pEFF) group (subset of the mITT population who received prior PLD).

RESULTS

One hundred thirty-nine patients were enrolled. Of the 132 patients in the mITT group, 20 achieved an ORR (15.2%; 95% CI 9.5-22.4); median PFS and OS were 4.4 months and 10.2 months, respectively. In the pEFF group (n=104), 15 patients (14.4%; 95% CI 8.3-22.7) achieved an ORR; median PFS and OS were 4.4 months and 10.9 months, respectively. The most common grade 3/4 toxicities were diarrhea (20%), abdominal pain (17%), vomiting (14%), dehydration (13%), and nausea (13%). Severe diarrhea was reduced to 15% with strict adherence to screening and management guidelines.

CONCLUSIONS

This study confirms the activity and safety of single-agent EP in patients with PROC, including patients who received prior PLD. Further evaluation earlier in the disease course and in combination is warranted.

The safety, efficacy, and treatment outcomes of a combination of low-dose decitabine treatment in patients with recurrent ovarian cancer

Purpose: DNA demethylating agents have shown clinical effectiveness in hematological and solid tumors. This trial tested the safety, efficacy, and treatment outcomes of decitabine-based chemotherapy or combined with immunotherapy in recurrent ovarian cancer patients. Patients and methods: Fifty-five patients with recurrent ovarian cancer were enrolled and 52 were assessable for clinical response and survival. Patients either received 5-d decitabine treatment, followed by reduced-dose of paclitaxel/carboplatin administration (DTC cohort), or the aforementioned regimen combined with cytokine-induced killer cells therapy (DTC+CIK cohort). The primary end point was clinical response rate and progression-free survival (PFS). Secondary evaluation included safety assessment and overall survival (OS). Results: Disease control rate (DCR) and objective response rate (ORR) were 73.91% and 23.91% in disease measurable patients by RECIST criteria, totally 76.92% and 30.77%, including disease non-measurable patients, which were higher in platinum-resistant/refractory patients. Clinical benefits could be associated with the number of DAC treatment cycles and the inclusion of CIK immunotherapy. In DTC+CIK cohort, DCR and ORR reached 100% and 58.30%, respectively. Notably, DTC+CIK treatment in platinum-resistant/refractory patients had an ORR of 87.50%. Consistently, PFS was longer in platinum-resistant/refractory patients comparing with that of platinum-sensitive patients. PFS and OS were 8 and 19 mo in platinum-resistant/refractory patients with DTC+CIK therapy. The most common toxicities were nausea, anorexia, fatigue, neutropenia, and anemia; many of which were grade 1-2. Conclusion: Low-dose DAC/paclitaxel/carboplatin regimen demonstrates disease benefit, especially in patients with platinum-resistant/refractory ovarian cancer, and might show remarkable clinical response when combined with adoptive immunotherapy in platinum-resistant/refractory ovarian cancer patients.

Factors favouring long-term survival following recurrence in ovarian cancer

The aim of the present study was to identify clinicopathological factors in long-term survivors following ovarian cancer recurrence. The patients who achieved longer survival after recurrence (n=18) and those who succumbed to the disease earlier (n=47) were identified and analyzed. There were no significant differences in age, performance status, stage distribution or histology between the two groups. Additionally, no significant difference was observed in progression-free survival after primary therapy. Multivariate analyses revealed that the predictive factors for long-term survival were i) secondary debulking surgery (OR=13.3; 95% CI: 1.39-226.7), ii) favourable response rate of second-line chemotherapy (OR=46.5; 95% CI: 1.84-313-4), and iii) ≥3 regimens after first recurrence (OR=9.01; 95% CI: 1.28-117.7). This study revealed that prolonged post-progression survival was associated with post-recurrence treatment. Therefore, appropriate selection of secondary debulking surgery and better chemotherapeutic response may lead to prolonged post-progression survival in recurrent ovarian cancer patients.

Tissue factor-factor VIIa complex triggers protease activated receptor 2-dependent growth factor release and migration in ovarian cancer

OBJECTIVE

Enhanced tissue factor (TF) expression in epithelial ovarian cancer (EOC) is associated with aggressive disease. Our objective was to evaluate the role of the TF-factor VIIa-protease-activated receptor-2 (PAR-2) pathway in human EOC.

METHODS

TCGA RNAseq data from EOC databases were analyzed for PAR expression. Cell and microparticle (MP) associated TF protein expression (Western blot) and MP-associated coagulant activity were determined in human EOC (SKOV-3, OVCAR-3 and CaOV-3) and control cell lines. PAR-1 and PAR-2 protein expressions were similarly examined. The PAR dependence of VEGF-A release (ELISA) and chemotactic migration in response to FVIIa and cellular proliferation in response to thrombin was evaluated with small molecule antagonists.

RESULTS

Relative mRNA expression consistently demonstrated PAR-2>PAR-1≫PAR-3/4 in multiple EOC datasets. Human EOC cell line lysates confirmed expression of TF, PAR-1 and PAR-2 proteins. MPs isolated from EOC cell lines demonstrated markedly enhanced (4-10 fold) TF coagulant activity relative to control cell lines. FVIIa induced a dose-dependent increase in VEGF-A release (2.5-3 fold) from EOC cell lines that was abrogated by the PAR-2 antagonist ENMD-1068. FVIIa treatment of CaOV-3 and OVCAR-3 cells resulted in increased chemotactic migration that was abolished by ENMD-1068. Thrombin induced dose-dependent EOC cell line proliferation was completely reversed by the PAR-1 antagonist vorapaxar. Small molecule antagonists had no effect on these phenotypes without protease present.

CONCLUSIONS

Enhanced activity of the TF-FVIIa-PAR-2 axis may contribute to the EOC progression via PAR-2 dependent signaling that supports an angiogenic and invasive phenotype and local thrombin generation supporting PAR-1 dependent proliferation.

NKTR-102 Efficacy versus irinotecan in a mouse model of brain metastases of breast cancer

Background

Brain metastases are an increasing problem in women with invasive breast cancer. Strategies designed to treat brain metastases of breast cancer, particularly chemotherapeutics such as irinotecan, demonstrate limited efficacy. Conventional irinotecan distributes poorly to brain metastases; therefore, NKTR-102, a PEGylated irinotecan conjugate should enhance irinotecan and its active metabolite SN38 exposure in brain metastases leading to brain tumor cytotoxicity.

Methods

Female nude mice were intracranially or intracardially implanted with human brain seeking breast cancer cells (MDA-MB-231Br) and dosed with irinotecan or NKTR-102 to determine plasma and tumor pharmacokinetics of irinotecan and SN38. Tumor burden and survival were evaluated in mice treated with vehicle, irinotecan (50 mg/kg), or NKTR-102 low and high doses (10 mg/kg, 50 mg/kg respectively).

Results

NKTR-102 penetrates the blood-tumor barrier and distributes to brain metastases. NKTR-102 increased and prolonged SN38 exposure (>20 ng/g for 168 h) versus conventional irinotecan (>1 ng/g for 4 h). Treatment with NKTR-102 extended survival time (from 35 days to 74 days) and increased overall survival for NKTR-102 low dose (30 % mice) and NKTR-102 high dose (50 % mice). Tumor burden decreased (37 % with 10 mg/kg NKTR-102 and 96 % with 50 mg/kg) and lesion sizes decreased (33 % with 10 mg/kg NKTR-102 and 83 % with 50 mg/kg NKTR-102) compared to conventional irinotecan treated animals.

Conclusions

Elevated and prolonged tumor SN38 exposure after NKTR-102 administration appears responsible for increased survival in this model of breast cancer brain metastasis. Further, SN38 concentrations observed in this study are clinically achieved with 145 mg/m² NKTR-102, such as those used in the BEACON trial, underlining translational relevance of these results.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1672-4) contains supplementary material, which is available to authorized users.

Fifteen years of irinotecan therapy for pediatric sarcoma: where to next?

Over the past 15 years, irinotecan has emerged as an important agent for treating pediatric sarcoma patients. This review summarizes the activity noted in previous studies, and outlines current issues regarding scheduling, route of administration, and amelioration of side effects. Also discussed are new pegylated and nanoliposomal formulations of irinotecan and its active metabolite, SN-38, as well as future plans for how irinotecan may be used in combination with other conventional cytotoxic as well as targeted agents.

Enhanced Delivery of SN-38 to Human Tumor Xenografts with an Anti-Trop-2-SN-38 Antibody Conjugate (Sacituzumab Govitecan)

PURPOSE

This study examined the delivery of SN-38 to Trop-2-expressing tumors and assessed the constitutive products in the serum, liver, and small intestine in nude mice bearing human tumor xenografts (Capan-1 or NCI-N87) given a single injection of irinotecan (40 mg/kg; ∼ 0.8 mg/mouse, containing ∼ 460 μg SN-38 equivalents) or sacituzumab govitecan (IMMU-132), an antibody-drug conjugate composed of a humanized anti-Trop-2 IgG coupled site specifically with an average of 7.6 molecules of SN-38.

EXPERIMENTAL DESIGN

At select times, tissues were extracted and concentrations of the products measured by reversed-phase high-performance liquid chromatography (HPLC).

RESULTS

In serum, >98% irinotecan cleared within 5 minutes; peak levels of SN-38 and SN-38G (glucuronidated SN-38) were detected in equal amounts at this time, and no longer detected after 6 to 8 hours. IMMU-132 was detected in the serum over 3 days, and at each interval, ≥ 95% of total SN-38 was bound to the antibody. Intact IMMU-132 cleared with a half-life of 14 hours, which closely reflected the in vitro rate of SN-38 released from the conjugate in mouse serum (i.e., 17.5 hours), whereas the IgG portion of the conjugate cleared with a half-life of 67.1 hours. In vitro and in vivo studies disclosed IgG-bound SN-38 was protected from glucuronidation. Area under the curve (AUC) analysis indicated that IMMU-132 delivers 20-fold to as much as 136-fold more SN-38 to tumors than irinotecan, with tumor:blood ratios favoring IMMU-132 by 20- to 40-fold. Intestinal concentrations of SN-38/SN-38G also were 9-fold lower with IMMU-132.

CONCLUSIONS

These studies confirm a superior SN-38 tumor delivery by IMMU-132 compared with irinotecan.

Phase II pilot study of single-agent etirinotecan pegol (NKTR-102) in bevacizumab-resistant high grade glioma

Patients with recurrence of high-grade glioma (HGG) after bevacizumab (BEV) have an extremely poor prognosis. Etirinotecan pegol (EP) is the first long-acting topoisomerase-I inhibitor designed to concentrate in and provide continuous tumor exposure throughout the entire chemotherapy cycle. Here we report results of a Phase 2, single arm, open-label trial evaluating EP in HGG patients who progressed after BEV. Patients age >18 with histologically proven anaplastic astrocytoma or glioblastoma (GB) who previously received standard chemo-radiation and recurred after BEV were eligible. A predicted life expectancy >6 weeks and KPS ≥ 50 were required. The primary endpoint was PFS at 6-weeks. Secondary endpoint was overall survival from first EP infusion. Response was assessed by RANO criteria. Single agent EP was administered IV every 3 weeks at 145 mg/m2. Patients did not receive BEV while on EP. 20 patients (90 % GB) were enrolled with a median age of 50 and median KPS of 70. Three patients with GB (16.7 % of GB) had partial MRI responses. 6-week PFS was 55 %. Median and 6-month PFS were 2.2 months (95 % CI 1.4–3.4 months) and 11.2 % (95 % CI 1.9–28.9 %) respectively. Median overall survival from first EP infusion was 4.5 months (95 % CI 2.4–5.9). Only one patient had grade 3 toxicity (diarrhea with dehydration) attributable to EP. Hematologic toxicity was mild. Three patients had confirmed partial responses according to RANO criteria. These clinical data combined with a favorable safety profile warrant further clinical investigation of this agent in HGG.

Drug conjugation to hyaluronan widens therapeutic indications for ovarian cancer

Management of ovarian cancer still requires improvements in therapeutic options. A drug delivery strategy was tested that allows specific targeting of tumor cells in combination with a controlled release of a cytotoxic molecule. To this aim, the efficacy of a loco-regional intraperitoneal treatment with a bioconjugate (ONCOFID-S) derived by chemical linking of SN-38, the active metabolite of irinotecan (CPT-11), to hyaluronan was assessed in a mouse model of ovarian carcinomatosis.

In vitro, the bioconjugate selectively interacted with ovarian cancer cells through the CD44 receptor, disclosed a dose-dependent tumor growth inhibition efficacy comparable to that of free SN-38 drug, and inhibited Topoisomerase I function leading to apoptosis by a mechanism involving caspase-3 and -7 activation and PARP cleavage. In vivo, the intraperitoneal administration of ONCOFID-S in tumor-bearing mice did not induce inflammation, and evidenced an improved therapeutic efficacy compared with CPT-11.

In conclusion, SN-38 conjugation to hyaluronan significantly improved the profile of in vivo tolerability and widened the field of application of irinotecan. Therefore, this approach can be envisaged as a promising therapeutic strategy for loco-regional treatment of ovarian cancer.

Phase 1 evaluation of EZN-2208, a polyethylene glycol conjugate of SN38, in children adolescents and young adults with relapsed or refractory solid tumors

BACKGROUND

EZN-2208 is a water-soluble PEGylated conjugate of the topoisomerase inhibitor SN38, the active metabolite of irinotecan. Compared to irinotecan, EZN-2208 has a prolonged half-life permitting extended exposure to SN38. EZN-2208 has demonstrated clinical tolerability and antitumor activity in adults with advanced solid tumors. This Phase 1 study evaluated the safety, pharmacokinetics, and preliminary antitumor activity of EZN-2208 in children with relapsed or refractory solid tumors.

PROCEDURE

EZN-2208 was administered as a 1-hour intravenous infusion once every 21 days at five dose levels (12-30 mg/m(2) ). Filgrastim or pegfilgrastim was administered 24-48 hours after treatment with EZN-2208. The rolling-six design was used for dose determination.

RESULTS

Thirty eligible patients (15 females; median [range] age 11.5 years [2-21 years]) were treated with EZN-2208. Dose-limiting diarrhea occurred in one patient receiving 16 mg/m(2) and dose-limiting dehydration was seen in one patient receiving 24 mg/m(2) . At dose levels above 16 mg/m(2) , Grade ≥3 myelosuppression was demonstrated in the majority of patients. Additional adverse events included nausea, vomiting, and fatigue. The maximum tolerated dose was identified as 24 mg/m(2) due to dose-limiting thrombocytopenia in two patients receiving 30 mg/m(2) . Two of nine patients with neuroblastoma who were evaluable for response had partial responses. Five patients (four with neuroblastoma) remained on study for ≥8 cycles.

CONCLUSIONS

EZN-2208 was generally well-tolerated and was associated with clinical benefit in patients with neuroblastoma.

Updates on drug discovery in ovarian cancer

Drug discovery in the ovarian cancer arena continues to launch important new clinical trials. Many biologic agents are being studied in phase II and phase III clinical trials for recurrent disease. These agents include compounds that disrupt angiogenesis through a variety of mechanisms. Other oncogenic pathways are also specifically targeted such as PARP, MEK, and topoisomerase inhibitors which are currently being studied in phase III trials. Various cytotoxic agents, as well as therapeutic vaccines, are also under investigation, and continue to demonstrate promising new data. The relevant agents in the treatment of ovarian cancer which have demonstrated positive phase II activity will be discussed.

Etirinotecan pegol: development of a novel conjugated topoisomerase I inhibitor

Irinotecan is a very active chemotherapeutic agent used for the treatment of several malignancies, including colorectal cancer, gastroesophageal tumors, lung cancer, breast cancer, ovarian cancer, and primary brain tumors. Irinotecan exerts its antineoplastic effects through its active metabolite 7-ethyl-10-hydroxycamptothecin. This metabolite is also responsible for the classic side effects associated with irinotecan that include diarrhea and neutropenia. A pegylated form of this agent, etirinotecan pegol, is undergoing clinical development with the main goal of increasing its therapeutic efficacy and its safety. This agent decreases the maximal exposure to 7-ethyl-10-hydroxycamptothecin while providing continuous exposure to the treated tumor. The half-life of etirinotecan pegol is 50 days and it has been studied in different schedules: weekly, every other week, and once every 3 weeks. The maximum tolerated dose of etirinotecan pegol was found to be 145 mg/m(2). There have already been two phase II clinical trials published showing the efficacy of this novel agent in the treatment of metastatic ovarian and breast cancer. The side effect profile was acceptable for most patients, with a number of patients experiencing diarrhea and even neutropenia.

Nonclinical pharmacokinetics and activity of etirinotecan pegol (NKTR-102), a long-acting topoisomerase 1 inhibitor, in multiple cancer models

Purpose

The aim of the study was to demonstrate the activity of etirinotecan pegol, a polymer conjugate of irinotecan, in multiple human tumor models and to establish both the pharmacokinetic/pharmacodynamics (PK/PD) relationship and clinical relevance of the findings.

Experimental design

Anti-tumor activity was evaluated in mouse models of human lung, colorectal, breast, ovarian, and gastric cancers. Etirinotecan pegol was administered intravenously (once or every 3–7 days) to animals with established tumors. Activity was assessed by tumor growth delay (TGD) and regression. Mice bearing established colorectal and lung tumors were treated with etirinotecan pegol or irinotecan, and serial blood and tumor samples were collected at planned times between 0 and 60 days post-treatment for quantitation of etirinotecan pegol and SN38. For PK analysis, analyte concentration–time data were fit with compartmental models; PK/PD analysis was based on an inhibitory E_max response model.

Results

Etirinotecan pegol was active in all tumor models. TGD was sustained for 2–10 weeks after last dose, while conventional irinotecan resulted in little suppression of tumor growth. Etirinotecan pegol was eliminated very slowly from the tumor (t_1/2 = 17 days), achieving higher and more sustained tumor exposure when compared with conventional irinotecan. The increased tumor exposure following etirinotecan pegol correlated with strong and prolonged suppression of tumor growth. Sustained plasma exposure to active SN38 was consistently observed across nonclinical species (including mouse, rat, and dog) and translated to cancer patients.

Conclusions

Etirinotecan pegol is the first long-acting topoisomerase 1 inhibitor that provides sustained exposure, which results in prolonged anti-tumor activity in a wide variety of cancer models.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-014-2577-7) contains supplementary material, which is available to authorized users.

Hypoxia-regulated gene network in drug resistance and cancer progression

Hypoxia is a common phenomenon of solid tumors and contributes to aggressive phenotype and treatment failure. Hypoxia-inducible factor (HIF), a versatile transcription factor that regulates more than 5% of total human genes, not only plays important roles in controlling physiological processes, but is also a crucial mediator in hypoxia-induced tumor progression and chemoresistance. Overexpression of HIF-1α is detected in a wide spectrum of cancers via different kinds of mechanisms, including reduced oxygen concentration, loss-of-function of tumor suppressor gene, activating mutation of oncogenes, and hyperactivation of protein kinase signaling pathways. HIF-regulated genes involve in many pathological processes such as metabolic switch, drug efflux, angiogenesis, cell proliferation, and anti-apoptosis, which ultimately leads to increased tumor growth and drug resistance. Due to the common failure of classic chemotherapeutic agents in treating hypoxic cancers, novel strategies have been developed to target tumors under hypoxic conditions including inhibition of HIF activity and administration of bioreductive drugs. These new strategies may provide more effective and specific methods in targeting hypoxic tumors.