The role of pregnancy associated plasma protein-A in triple negative breast cancer: a promising target for achieving clinical benefits

Pregnancy associated plasma protein-A (PAPP-A) plays an integral role in breast cancer (BC), especially triple negative breast cancer (TNBC). This subtype accounts for the most aggressive BC, possesses high tumor heterogeneity, is least responsive to standard treatments and has the poorest clinical outcomes. There is a critical need to address the lack of effective targeted therapeutic options available. PAPP-A is a protein that is highly elevated during pregnancy. Frequently, higher PAPP-A expression is detected in tumors than in healthy tissues. The increase in expression coincides with increased rates of aggressive cancers. In BC, PAPP-A has been demonstrated to play a role in tumor initiation, progression, metastasis including epithelial-mesenchymal transition (EMT), as well as acting as a biomarker for predicting patient outcomes. In this review, we present the role of PAPP-A, with specific focus on TNBC. The structure and function of PAPP-A, belonging to the pappalysin subfamily, and its proteolytic activity are assessed. We highlight the link of BC and PAPP-A with respect to the IGFBP/IGF axis, EMT, the window of susceptibility and the impact of pregnancy. Importantly, the relevance of PAPP-A as a TNBC clinical marker is reviewed and its influence on immune-related pathways are explored. The relationship and mechanisms involving PAPP-A reveal the potential for more treatment options that can lead to successful immunotherapeutic targets and the ability to assist with better predicting clinical outcomes in TNBC.

A phase II trial of nivolumab followed by ipilimumab and nivolumab in advanced non-clear-cell renal cell carcinoma

OBJECTIVE

To evaluate the efficacy of sequential treatment with ipilimumab and nivolumab following progression on nivolumab monotherapy in individuals with advanced, non-clear-cell renal cell carcinoma (nccRCC).

MATERIALS AND METHODS

UNISoN (ANZUP1602; NCT03177239) was an open-label, single-arm, phase 2 clinical trial that recruited adults with immunotherapy-naïve, advanced nccRCC. Participants received nivolumab 240 mg i.v. two-weekly for up to 12 months (Part 1), followed by sequential addition of ipilimumab 1 mg/kg three-weekly for four doses to nivolumab if disease progression occurred during treatment (Part 2). The primary endpoint was objective tumour response rate (OTRR) and secondary endpoints included duration of response (DOR), progression-free (PFS) and overall survival (OS), and toxicity (treatment-related adverse events).

RESULTS

A total of 83 participants were eligible for Part 1, including people with papillary (37/83, 45%), chromophobe (15/83, 18%) and other nccRCC subtypes (31/83, 37%); 41 participants enrolled in Part 2. The median (range) follow-up was 22 (16-30) months. In Part 1, the OTRR was 16.9% (95% confidence interval [CI] 9.5-26.7), the median DOR was 20.7 months (95% CI 3.7-not reached) and the median PFS was 4.0 months (95% CI 3.6-7.4). Treatment-related adverse events were reported in 71% of participants; 19% were grade 3 or 4. For participants who enrolled in Part 2, the OTRR was 10%; the median DOR was 13.5 months (95% CI 4.8-19.7) and the median PFS 2.6 months (95% CI 2.2-3.8). Treatment-related adverse events occurred in 80% of these participants; 49% had grade 3, 4 or 5. The median OS was 24 months (95% CI 16-28) from time of enrolment in Part 1.

CONCLUSIONS

Nivolumab monotherapy had a modest effect overall, with a few participants experiencing a long DOR. Sequential combination immunotherapy by addition of ipilimumab in the context of disease progression to nivolumab in nccRCC is not supported by this study, with only a minority of participants benefiting from this strategy.

In Vitro and In Silico Analysis of Epithelial-Mesenchymal Transition and Cancer Stemness as Prognostic Markers of Clear Cell Renal Cell Carcinoma

The process of epithelial-mesenchymal transition (EMT) involves the phenotypic transformation of cells from epithelial to mesenchymal status. The cells exhibiting EMT contain features of cancer stem cells (CSC), and the dual processes are responsible for progressive cancers. Activation of hypoxia-inducible factors (HIF) is fundamental to the pathogenesis of clear cell renal cell carcinoma (ccRCC), and their role in promoting EMT and CSCs is crucial for ccRCC tumour cell survival, disease progression, and metastatic spread. In this study, we explored the status of HIF genes and their downstream targets, EMT and CSC markers, by immunohistochemistry on in-house accrued ccRCC biopsies and adjacent non-tumorous tissues from patients undergoing partial or radical nephrectomy. In combination, we comprehensively analysed the expression of HIF genes and its downstream EMT and CSC-associated targets relevant to ccRCC by using publicly available datasets, the cancer genome atlas (TCGA) and the clinical proteome tumour analysis consortium (CPTAC). The aim was to search for novel biological prognostic markers that can stratify high-risk patients likely to experience metastatic disease. Using the above two approaches, we report the development of novel gene signatures that may help to identify patients at a high risk of developing metastatic and progressive disease.

Precision Medicine: An Optimal Approach to Patient Care in Renal Cell Carcinoma

Renal cell cancer (RCC) is a heterogeneous tumor that shows both intra- and inter-heterogeneity. Heterogeneity is displayed not only in different patients but also among RCC cells in the same tumor, which makes treatment difficult because of varying degrees of responses generated in RCC heterogeneous tumor cells even with targeted treatment. In that context, precision medicine (PM), in terms of individualized treatment catered for a specific patient or groups of patients, can shift the paradigm of treatment in the clinical management of RCC. Recent progress in the biochemical, molecular, and histological characteristics of RCC has thrown light on many deregulated pathways involved in the pathogenesis of RCC. As PM-based therapies are rapidly evolving and few are already in current clinical practice in oncology, one can expect that PM will expand its way toward the robust treatment of patients with RCC. This article provides a comprehensive background on recent strategies and breakthroughs of PM in oncology and provides an overview of the potential applicability of PM in RCC. The article also highlights the drawbacks of PM and provides a holistic approach that goes beyond the involvement of clinicians and encompasses appropriate legislative and administrative care imparted by the healthcare system and insurance providers. It is anticipated that combined efforts from all sectors involved will make PM accessible to RCC and other patients with cancer, making a tremendous positive leap on individualized treatment strategies. This will subsequently enhance the quality of life of patients.

CD73 and PD-L1 as Potential Therapeutic Targets in Gallbladder Cancer

Gallbladder cancer (GBC) is one of the most common and aggressive biliary tract cancers with a dismal prognosis. Ongoing clinical trials are evaluating a few selected immune checkpoint inhibitors (ICIs) as monotherapy for the treatment of GBC patients. However, only a subset of patients benefits from these treatments. To improve ICI therapy response, molecular mechanisms that confer resistance to immune checkpoint (IC) blockade needs to be explored. Epithelial-to-mesenchymal transition (EMT) program and cancer stem cells (CSCs) have been implicated as key processes that confer ICI treatment resistance. However, in GBC the EMT-CSC-IC axis has not yet been clearly elucidated. This study aims to examine the aberrant expression of ICs associated with CSC and EMT. We successfully enriched CSCs by utilizing a 3-dimensional culture system and established a reversible EMT model with human GBC NOZ cell line. Notably, ICs CD73 and PD-L1 were closely associated with both CSC and EMT phenotypes. Knockdown of CD73 or PD-L1 reduced the proliferative and motile abilities of both adherent monolayers and anchorage-free spheroids. In conclusion, blocking CD73 and PD-L1 offer a promising therapeutic strategy for targeting highly aggressive populations with CSC and EMT phenotype to improve GBC patient prognosis.

Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

Vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) have been the mainstay of treatment for patients with advanced renal cell carcinoma (RCC). Despite its early promising results in decreasing or delaying the progression of RCC in patients, VEGF-TKIs have provided modest benefits in terms of disease-free progression, as 70% of the patients who initially respond to the treatment later develop drug resistance, with 30% of the patients innately resistant to VEGF-TKIs. In the past decade, several molecular and genetic mechanisms of VEGF-TKI resistance have been reported. One of the mechanisms of VEGF-TKIs is inhibition of the classical angiogenesis pathway. However, recent studies have shown the restoration of an alternative angiogenesis pathway in modulating resistance. Further, in the last 5 years, immune checkpoint inhibitors (ICIs) have revolutionized RCC treatment. Although some patients exhibit potent responses, a non-negligible number of patients are innately resistant or develop resistance within a few months to ICI therapy. Hence, an understanding of the mechanisms of VEGF-TKI and ICI resistance will help in formulating useful knowledge about developing effective treatment strategies for patients with advanced RCC. In this article, we review recent findings on the emerging understanding of RCC pathology, VEGF-TKI and ICI resistance mechanisms, and potential avenues to overcome these resistance mechanisms through rationally designed combination therapies.

Ipilimumab + nivolumab in people with rare variant renal cell carcinoma refractory to nivolumab alone: Part 2 of UNISON (ANZUP 1602) nivolumab then ipilimumab + nivolumab in advanced non-clear cell renal cell carcinoma

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Background: Immunotherapy targeting PD1 is active across many cancers, but many people are failed by PD1 inhibition alone. UNISON (ANZUP 1602/NCT03177239) has previously reported the activity and outcomes of nivolumab monotherapy in people with nccRCC (OTRR 17%, PFS6 45%; part 1), and here we report the outcomes of combining ipilimumab (I) and nivolumab (N), in people whose cancers are refractory to N alone (part 2). Methods: Participants (pts) with advanced nccRCC with good performance status (ECOG 0/1), were initially enrolled and took N alone. 41 pts refractory to N were offered the combination I (1mg/kg) + N (3mg/kg) every 3 weeks for up to 4 doses. Pts with disease control after N, or N + I could continue N for up to 1 year. UNISON was powered to distinguish a clinically relevant improvement in objective tumour response rate (OTRR) from 15% to 30% in people taking I+N in part 2. Results: 85 pts were enrolled and received N. 41 pts were refractory to N, were well enough to take I+N, and had a representative spectrum of nccRCC histologies (n=41; papillary 44%, chromophobe 20%, Xp11 translocation 12%, RCC unclassified 7%, other 17%). The median time on treatment was 2.1 months, the median number of doses was 3; median follow up at the time of reporting was 20.3 months. The OTRR of I+N in pts refractory to N was 10% with 1 complete and 3 partial responses. Stable disease was experienced by 36% of pts and disease progression by 52%. The disease control rate at 6 months was 45% (95% CI: 34%, 56%). The median PFS was 2.6 months (95% CI: 2.2, 3.8). The 6 month progression-free survival (PFS) was 25% (95% CI: 13-39). Only 14% of patients were free of progression at 12 months. The safety of I+N appeared similar to previous reports. 68% of pts experienced serious adverse events, 34% treatment related SAE. One pt died from refractory pneumonitis. 11 pts (27%) experienced treatment delays or permanent treatment discontinuation. Conclusions: The primary endpoint of the study was not met. A minority of pts with nccRCC refractory to nivolumab derive benefit from combination I+N but many pts remain refractory to immunotherapy. No new safety issues were identified. More effective therapeutic options are needed for people with rare variant renal cell carcinoma. Clinical trial information: NCT03177239.

UNISON - nivolumab then ipilimumab + nivolumab in advanced non-clear cell renal cell carcinoma (ANZUP 1602): Part 1—Nivolumab monotherapy

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Background: Immune checkpoint inhibitors (ICI) are active in many cancers, but people with rare variant, non clear-cell renal cell carcinoma (nccRCC) have been excluded from most clinical trials in RCC. UNISON (NCT03177239) aimed to test 2 hypotheses; the activity of nivolumab in nccRCC (Part 1), and the benefit of adding ipilimumab to nivolumab, in people whose cancers progress on nivolumab (Part 2). Methods: 83 participants (pts) with advanced nccRCC with good (ECOG0/1) performance status, were enrolled including papillary type 1 (17%), papillary type 2 (28%), chromophobe (18%), Xp11 translocation (6%), hereditary leiomyomatosis renal cell carcinoma syndrome-associated renal cell carcinoma (6%), RCC unclassified (10%) and other (15%) histological subtypes. Participants took nivolumab (N) 240mg every two weeks in Part 1 in total. If they experienced progression and remained eligible they could take N (3mg/kg) plus ipilimumab (I; 1mg/kg) every 3 weeks for up to 4 doses (Part 2). Pts with disease control after N or N + I could continue N for up to 1 year. UNISON was powered to distinguish a clinically-relevant improvement in objective tumor response rate (OTRR) from 15% to 30% in people taking N+I in Part 2 in pts whose cancers were refractory to single-agent first-line N. Here we report results of Part 1. Results: Pts experience of N appeared similar to previous reports, with most experiencing mild adverse events. 12 treatment related SAE occurred in 11 patients (13%). 14 pts (17%) experienced treatment delays, or permanent treatment discontinuation (10%). The median time on treatment was 5.1 months. The OTRR was 17% with 3 complete responses and 11 partial responses. The median duration of response was 21 months. Stable disease occurred in 49% of pts and disease progression in 34%. The disease control rate at 6 months was 45% (95% CI: 34%, 56%). The median PFS was 4.0 months (95% CI: 3.6, 7.4). The 6 month progression-free survival (PFS) was 45% (95% CI: 34-55) and the 12 months PFS was 30% (95% CI: 21%, 40%). Conclusions: Pts with nccRCC treated with N experience similar adverse events compared to pts with other cancers. A substantial minority of people with nccRCC derive benefit, but many pts have cancers refractory to anti-PD1, similar to other reports. The activity of I and N in this PD1-refractory population is of considerable interest and will be reported at a later date. Clinical trial information: NCT03177239 .

Denosumab and pembrolizumab in clear cell renal carcinoma (KEYPAD): A phase II trial (ANZUP1601)

TPS367

Background: Inhibitors of the programmed death-1 pathway (PD-1) are effective in clear cell renal cell cancer (ccRCC). Preclinical data and case reports suggest that denosumab, an inhibitor of Receptor Activator of Nuclear Factor κ-B Ligand (RANKL) signaling, could potentiate the anti-tumour effects of anti-PD1 inhibitors without overlapping toxicities. We aim to determine the activity and safety of combining denosumab and pembrolizumab in advanced ccRCC. Methods: This single arm, multi-center, phase II trial will recruit 70 participants with metastatic or unresectable ccRCC, progressing during or after treatment with vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors, and with no prior treatment with immunotherapy or denosumab. Participants will receive pembrolizumab 200mg IV every 3 weeks plus denosumab 120mg SC on days 1, 8 and 22 and then every 3 weeks until disease progression, prohibitive toxicity or maximum treatment of 24 months. Response will be assessed at weeks 12, 18, 24, then every 12 weeks until disease progression. Bloods for translational studies are collected at baseline, week 6 and on disease progression. The primary endpoint is objective tumour response rate (OTRR) per RECIST 1.1. Secondary endpoints include OTRR per iRECIST, progression free survival (PFS), time to OTRR, time to first skeletal related event, adverse events, and frequency of treatment delays/discontinuations. Correlative studies will include identification of prognostic and/or predictive biomarkers relating to immune and RANKL signaling. A sample size of 70 provides 90% power with a 1-sided type 1 error rate of 10% to distinguish the observed OTRR (and PFS at 6 months) from an OTRR of 40% (worthy of pursuit) versus 25% (not worthy of pursuit). 15 sites are open across Australia. As of September 23, 2020, 40 patients have been recruited. Clinical trial information: NCT03280667 .

Eftilagimod alpha, a soluble lymphocyte activation gene-3 (LAG-3) protein plus pembrolizumab in patients with metastatic melanoma

BACKGROUND

To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of eftilagimod alpha (efti), a soluble lymphocyte activation gene-3 protein, in combination with the programmed cell death-1 (PD-1) antagonist pembrolizumab.

METHODS

The study was divided into two parts; parts A and B, where part A was the dose escalation part and part B was an extension part of the study. Patients with metastatic melanoma were treated with efti plus the standard dose of pembrolizumab. Blood samples were assayed to determine plasma pharmacokinetic parameters, detect efti antibody formation and determine long-lived CD8 T cell responses and associated pharmacodynamic parameters.

RESULTS

Twenty-four patients with melanoma received pembrolizumab and bi-weekly subcutaneous (s.c.) injections of efti at doses 1 mg, 6 mg or 30 mg/injection for up to 6 months (part A) or 30 mg/injection for up 12 months (part B). No dose-limiting toxicities were reported and the main adverse event for efti was injection site reactions. Sustained systemic exposure to the product was obtained in all patients following s.c. injections of 30 mg dose. Treatment induced an increase in activated CD8 and CD4 T cell counts, and in some of the soluble biomarkers, particularly interferon (IFN)-γ, a Th1 signature cytokine. An overall response rate (ORR) of 33% was observed in patients partly with pembrolizumab-refractory of part A and ORR of 50% was observed in patients with PD-1 naïve of part B.

CONCLUSIONS

Efti was well tolerated in combination with pembrolizumab with encouraging antitumor activity. This warrants further clinical studies of this new combination therapy combining an antigen-presenting cell activator with an immune checkpoint inhibitor.

Aberrant pregnancy-associated plasma protein-A expression in breast cancers prognosticates clinical outcomes

Elevated levels of pregnancy-associated plasma protein-A (PAPP-A) have been implicated in the pathogenesis of various malignancies, including breast cancers. Breast cancer is one of the most frequent carcinomas and is the second most common cancer type detected in women of child-bearing age. Throughout pregnancy PAPP-A is produced and secreted by the placental syncytiotrophoblast cells; co-incidentally pregnancy-associated breast cancers often have an aggressive clinical course. The components of the PAPP-A/IGF axis was assessed in a panel of breast cancer cell lines. Using neutralising antibodies the impact of PAPP-A/IGF axis on cell motility was evaluated. PAPP-A was expressed in four of the twelve breast cancer cell lines tested. Blocking PAPP-A and IGFBP4 with neutralising antibodies significantly decreased motiliy of MDA-MB-231 cells. Upregulation of PAPP-A expression in breast tumours resulted in a trend towards worse overall survival. Notably, PAPP-A expression also positively correlated with epithelial-to-mesenchymal transition markers. In conclusion, these results indicate that PAPP-A plays an important role in breast cancer progression and it may be a promising therapeutic target in breast cancer.

UNISON: Nivolumab then ipilimumab + nivolumab in advanced nonclear cell renal cell carcinoma (ANZUP 1602)

TPS768

Background: Renal cell carcinomas (RCC) are predominantly the clear cell (cc) subtype, with a unique biology, characterized by sensitivity to angiogenesis inhibition. However vascular endothelial growth factor-tyrosine kinase inhibitors elicit modest responses in people with rare variant non-clear cell (ncc) RCC. Immune checkpoint inhibitors (ICI) are active against many cancers, but people with rare variant nccRCC have been excluded from frontline trials despite experiencing a more aggressive disease course and poorer prognosis compared to those with ccRCC. UNISON (NCT03177239) aims to test 2 ideas; the activity of ICI in nccRCC, and the novel sequencing strategy of anti-programmed cell death protein (PD)1 immunotherapy, followed by the combination of anti-PD1 and anti-cytotoxic T-lymphocyte-associated protein (CTLA)4 blockade, in people failed by single agent treatment. Methods: This single-arm, two-part trial recruits people of good performance status suffering metastatic or locally advanced unresectable rare variant nccRCC, including but not limited to papillary (type 1/2), chromophobe, sarcomatoid, Xp11 translocation, collecting duct, and unclassified histological subtypes. Participants are offered fixed dose nivolumab at 240mg every two weeks in Part 1 of the trial. If they experience progressive disease, eligible participants may proceed to Part 2 consisting of nivolumab (3mg/kg) plus ipilimumab (1mg/kg) every 3 weeks for up to 4 doses. People experiencing disease control after single-agent or combined ICI are eligible to continue treatment for up to 1 year. UNISON is powered to distinguish a clinically non-relevant objective tumor response rate (OTRR) of 15% in people taking combination ICI whose cancers are refractory to single-agent PD1, versus a clinically-relevant OTRR of 30% at 5% level of significance with 80% power. 85 participants were recruited in Part 1, on the assumption that 55% of those entering Part 1 will be eligible for inclusion in Part 2. Enrolment commenced in November 2017 and was completed ahead of schedule in September 2019. Of the 48 participants projected to experience progression on anti-PD1 immunotherapy, 36 have so far commenced combination ICI in Part 2. Clinical trial information: NCT03177239.

Monitoring Immune Checkpoint Regulators as Predictive Biomarkers in Hepatocellular Carcinoma

The global burden of hepatocellular carcinoma (HCC), one of the frequent causes of cancer-related deaths worldwide, is rapidly increasing partly due to the limited treatment options available for this disease and recurrence due to therapy resistance. Immune checkpoint inhibitors that are proved to be beneficial in the treatment of advanced melanoma and other cancer types are currently in clinical trials in HCC. These ongoing trials are testing the efficacy and safety of a few select checkpoints in HCC. Similar to observations in other cancers, these immune checkpoint blockade treatments as monotherapy may benefit only a fraction of HCC patients. Studies that assess the prevalence and distribution of other immune checkpoints/modulatory molecules in HCC have been limited. Moreover, robust predictors to identify which HCC patients will respond to immunotherapy are currently lacking. The objective of this study is to perform a comprehensive evaluation on different immune modulators as predictive biomarkers to monitor HCC patients at high risk for poor prognosis. We screened publically available HCC patient databases for the expression of previously well described immune checkpoint regulators and evaluated the usefulness of these immune modulators to predict high risk, patient overall survival and recurrence. We also identified the immune modulators that synergized with known immune evasion molecules programmed death receptor ligand-1 (PD-L1), programmed cell death protein-1 (PD-1), and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and correlated with worse patient outcomes. We evaluated the association between the expression of epithelial-to-mesenchymal transition (EMT) markers and PD-L1 in HCC patient tumors. We also examined the relationship of tumor mutational burden with HCC patient survival. Notably, expression of immune modulators B7-H4, PD-L2, TIM-3, and VISTA were independently associated with worse prognosis, while B7-H4, CD73, and VISTA predicted low recurrence-free survival. Moreover, the prognosis of patients expressing high PD-L1 with high B7-H4, TIM-3, VISTA, CD73, and PD-L2 expression was significantly worse. Interestingly, PD-L1 expression in HCC patients in the high-risk group was closely associated with EMT marker expression and prognosticates poor survival. In HCC patients, high tumor mutational burden (TMB) predicted worse patient outcomes than those with low TMB.

Identifying and targeting determinants of melanoma cellular invasion

Epithelial-to-mesenchymal transition is a critical process that increases the malignant potential of melanoma by facilitating invasion and dissemination of tumor cells. This study identified genes involved in the regulation of cellular invasion and evaluated whether they can be targeted to inhibit melanoma invasion. We identified Peroxidasin (PXDN), Netrin 4 (NTN4) and GLIS Family Zinc Finger 3 (GLIS3) genes consistently elevated in invasive mesenchymal-like melanoma cells. These genes and proteins were highly expressed in metastatic melanoma tumors, and gene silencing led to reduced melanoma invasion in vitro. Furthermore, migration of PXDN, NTN4 or GLIS3 siRNA transfected melanoma cells was inhibited following transplantation into the embryonic chicken neural tube compared to control siRNA transfected melanoma cells. Our study suggests that PXDN, NTN4 and GLIS3 play a functional role in promoting melanoma cellular invasion, and therapeutic approaches directed toward inhibiting the action of these proteins may reduce the incidence or progression of metastasis in melanoma patients.

Pregnancy associated plasma protein-A links pregnancy and melanoma progression by promoting cellular migration and invasion

Melanoma is the most common cancer diagnosed in pregnant women and an aggressive course with poorer outcomes is commonly described during pregnancy or shortly after childbirth. The underlying mechanisms for this are not understood. Here, we report that melanoma migration, invasiveness and progression are promoted by pregnancy-associated plasma protein-A (PAPPA), a pregnancy-associated metalloproteinase produced by the placenta that increases the bioavailability of IGF1 by cleaving it from a circulating complex formed with IGFBP4. We show that PAPPA is widely expressed by metastatic melanoma tumors and is elevated in melanoma cells exhibiting mesenchymal, invasive and label-retaining phenotypes. Notably, inhibition of PAPPA significantly reduced invasion and migration of melanoma cells in vitro and in vivo within the embryonic chicken neural tube. PAPPA-enriched pregnancy serum treatment enhanced melanoma motility in vitro. Furthermore, we report that IGF1 can induce the phenotypic and functional effects of epithelial-to-mesenchymal transition (EMT) in melanoma cells. In this study, we establish a clear relationship between a pregnancy-associated protein PAPPA, melanoma and functional effects mediated through IGF1 that provides a plausible mechanism for accelerated melanoma progression during pregnancy. This opens the possibility of targeting the PAPPA/IGF1 axis therapeutically.

Efficacy and toxicity of treatment with the anti-CTLA-4 antibody ipilimumab in patients with metastatic melanoma after prior anti-PD-1 therapy

Background:

Recent phase III clinical trials have established the superiority of the anti-PD-1 antibodies pembrolizumab and nivolumab over the anti-CTLA-4 antibody ipilimumab in the first-line treatment of patients with advanced melanoma. Ipilimumab will be considered for second-line treatment after the failure of anti-PD-1 therapy.

Methods:

We retrospectively identified a cohort of 40 patients with metastatic melanoma who received single-agent anti-PD-1 therapy with pembrolizumab or nivolumab and were treated on progression with ipilimumab at a dose of 3 mg kg⁻¹ for a maximum of four doses.

Results:

Ten percent of patients achieved an objective response to ipilimumab, and an additional 8% experienced prolonged (>6 months) stable disease. Thirty-five percent of patients developed grade 3–5 immune-related toxicity associated with ipilimumab therapy. The most common high-grade immune-related toxicity was diarrhoea. Three patients (7%) developed grade 3–5 pneumonitis leading to death in one patient.

Conclusions:

Ipilimumab therapy can induce responses in patients who fail the anti-PD-1 therapy with response rates comparable to previous reports. There appears to be an increased frequency of high-grade immune-related adverse events including pneumonitis that warrants close surveillance.

Transketolase-like 1 ectopic expression is associated with DNA hypomethylation and induces the Warburg effect in melanoma cells

BACKGROUND

The metabolism of cancer cells is often reprogrammed by dysregulation of metabolic enzymes. Transketolase-like 1 (TKTL1) is a homodimeric transketolase linking the pentose-phosphate pathway with the glycolytic pathway. It is generally silenced at a transcriptional level in somatic tissues. However, in human cancers its expression is associated with the acquisition of a glycolytic phenotype (the Warburg effect) by cancer cells that contributes to the progression of malignant tumors. In melanoma, defective promoter methylation results in the expression of genes and their products that can affect the tumor cell's phenotype including the modification of immune and functional characteristics. The present study evaluates the role of TKTL1 as a mediator of disease progression in melanoma associated with a defective methylation phenotype.

METHODS

The expression of TKTL1 in metastatic melanoma tumors and cell lines was analysed by qRT-PCR and immunohistochemistry. The promoter methylation status of TKTL1 in melanoma cells was evaluated by quantitative methylation specific PCR. Using qRT-PCR, the effect of a DNA demethylating agent 5-aza-2'-deoxycytidine (5aza) on the expression of TKTL1 was examined. Biochemical and molecular analyses such as glucose consumption, lactate production, invasion, proliferation and cell cycle progression together with ectopic expression and siRNA mediated knockdown were used to investigate the role of TKTL1 in melanoma cells.

RESULTS

Expression of TKTL1 was highly restricted in normal adult tissues and was overexpressed in a subset of metastatic melanoma tumors and derived cell lines. The TKTL1 promoter was activated by hypomethylation and treatment with 5aza induced TKTL1 expression in melanoma cells. Augmented expression of TKTL1 in melanoma cells was associated with a glycolytic phenotype. Loss and gain of function studies revealed that TKTL1 contributed to enhanced invasion of melanoma cells.

CONCLUSIONS

Our data provide evidence for an important role of TKTL1 in aerobic glycolysis and tumor promotion in melanoma that may result from defective promoter methylation. This epigenetic change may enable the natural selection of tumor cells with a metabolic phenotype and thereby provide a potential therapeutic target for a subset of melanoma tumors with elevated TKTL1 expression.

Thrombospondin 1 promotes an aggressive phenotype through epithelial-to-mesenchymal transition in human melanoma

Epithelial-to-mesenchymal transition (EMT), in which epithelial cells loose their polarity and become motile mesenchymal cells, is a determinant of melanoma metastasis. We compared gene expression signatures of mesenchymal-like melanoma cells with those of epithelial-like melanoma cells, and identified Thrombospondin 1 (THBS1) as highly up-regulated in the mesenchymal phenotype. This study investigated whether THBS1, a major physiological activator of transforming growth factor (TGF)-beta, is involved in melanoma EMT-like process. We sought to examine expression patterns in distinct melanoma phenotypes including invasive, de-differentiated, label-retaining and drug resistant populations that are putatively associated with an EMT-like process.

Here we show that THBS1 expression and secretion was elevated in melanoma cells exhibiting invasive, drug resistant, label retaining and mesenchymal phenotypes and correlated with reduced expression of genes involved in pigmentation. Elevated THBS1 levels were detected in Vemurafenib resistant melanoma cells and inhibition of THBS1 led to significantly reduced chemoresistance in melanoma cells. Notably, siRNA-mediated silencing of THBS1 and neutralizing antibody to THBS1 reduced invasion in mesenchymal-like melanoma cells, while ectopic THBS1 expression in epithelial-like melanoma cells enhanced invasion. Furthermore, the loss of THBS1 inhibited in vivo motility of melanoma cells within the embryonic chicken neural tube. In addition, we found aberrant THBS1 protein expression in metastatic melanoma tumor biopsies. These results implicate a role for THBS1 in EMT, and hence THBS1 may serve as a novel target for strategies aimed at the treatment of melanoma invasion and drug resistance.

Embryonic Chicken Transplantation is a Promising Model for Studying the Invasive Behavior of Melanoma Cells

Epithelial-to-mesenchymal transition is a hallmark event in the metastatic cascade conferring invasive ability to tumor cells. There are ongoing efforts to replicate the physiological events occurring during mobilization of tumor cells in model systems. However, few systems are able to capture these complex in vivo events. The embryonic chicken transplantation model has emerged as a useful system to assess melanoma cells including functions that are relevant to the metastatic process, namely invasion and plasticity. The chicken embryo represents an accessible and economical 3-dimensional in vivo model for investigating melanoma cell invasion as it exploits the ancestral relationship between melanoma and its precursor neural crest cells. We describe a methodology that enables the interrogation of melanoma cell motility within the developing avian embryo. This model involves the injection of melanoma cells into the neural tube of chicken embryos. Melanoma cells are labeled using fluorescent tracker dye, Vybrant DiO, then cultured as hanging drops for 24 h to aggregate the cells. Groups of approximately 700 cells are placed into the neural tube of chicken embryos prior to the onset of neural crest migration at the hindbrain level (embryonic day 1.5) or trunk level (embryonic day 2.5). Chick embryos are reincubated and analyzed after 48 h for the location of melanoma cells using fluorescent microscopy on whole mounts and cross-sections of the embryos. Using this system, we compared the in vivo invasive behavior of epithelial-like and mesenchymal-like melanoma cells. We report that the developing embryonic microenvironment confers motile abilities to both types of melanoma cells. Hence, the embryonic chicken transplantation model has the potential to become a valuable tool for in vivo melanoma invasion studies. Importantly, it may provide novel insights into and reveal previously unknown mediators of the metastatic steps of invasion and dissemination in melanoma.

Interleukin 1 administration in mice produces hypoferremia despite neutropenia

To determine whether the hypoferremic response to inflammation requires neutrophils, we administered human recombinant IL-1 to mice made neutropenic with cyclophosphamide. With single intraperitoneal injections of IL-1 the plasma iron concentrations decreased significantly in mice with either normal neutrophil counts or neutropenia. After single injections transferrin concentrations were not significantly changed, but the decrease in serum iron lowered mean transferrin saturations from a baseline of 45 to 24-30% in nonneutropenic mice, and from 99 to 70-77% in neutropenic mice. Similar changes were observed after intraperitoneal injections of Escherichia coli. 4-d continuous infusions of IL-1 also led to reductions in serum iron concentrations, but transferrin concentrations doubled. The combination of a decrease in serum iron and an increase in transferrin concentration after chronic infusion in neutropenic mice led to a greater decline in mean transferrin saturations, from a baseline of 110 to 25%. In mice not given cyclophosphamide, chronic IL-1 infusion was associated with a reduction in mean hemoglobin concentrations from 14.7 to 13.5 g/dl, consistent with restricted availability of iron for erythropoiesis associated with low saturation of transferrin. We conclude that IL-1 can decrease the serum iron despite profound peripheral neutropenia and that transferrin in a positive acute phase reactant in the mouse.