The effect of a single dose of nivolumab prior to isolated limb perfusion for patients with in-transit melanoma metastases: An interim analysis of a phase Ib/II randomized double-blind placebo-controlled trial (NivoILP trial)

OBJECTIVE

ILP has shown to achieve high response rates in patients with melanoma ITM. Possibly there is a synergistic mechanism of action of ILP and anti-PD1. The aim of this trial was to investigate the safety and efficacy of adding a single dose of systemic anti-PD1 to isolated limb perfusion (ILP) for patients with melanoma in-transit metastases (ITM).

METHODS

In this placebo controlled double-blind phase Ib/II trial, patients with melanoma ITM were randomized 1:1 to either a single systemic dose of nivolumab or placebo one day prior to ILP. The primary endpoint was complete response (CR) rate at three months, and safety in terms of incidence and severity of adverse events (AEs).

RESULTS

A total of 20 patients were included. AEs of any grade occurred in 90% of patients in the nivolumab arm and in 80% in the placebo arm within three months after ILP. Grade 3 AEs were reported in 40% and 30% respectively, most commonly related to wound infection, wound dehiscence, or skin necrosis. There were no grade 4 or 5 AEs reported. The CR rate was 75% in the nivolumab arm and 60% in the placebo arm. The 1-year local progression-free rate was 86% in the nivolumab arm and 67% in the placebo arm. The 1-year OS was 100% in both arms.

CONCLUSION

For patients with melanoma ITM, the addition of a single systemic dose of nivolumab the day before ILP is considered safe and feasible with promising efficacy. Accrual will continue in a phase 2 trial.

MYB alternative promoter activity is increased in adenoid cystic carcinoma metastases and is associated with a specific gene expression signature

OBJECTIVE

Adenoid cystic carcinoma (ACC) is a head and neck cancer with a poor long-term prognosis that shows frequent local recurrences and distant metastases. The tumors are characterized by MYB oncogene activation and are notoriously unresponsive to systemic therapies. The biological underpinnings behind therapy resistance of disseminated ACC are largely unknown. Here, we have studied the molecular and clinical significance of MYB alternative promoter (TSS2) usage in ACC metastases.

MATERIALS AND METHODS

MYB TSS2 activity was investigated in primary tumors and metastases from 26 ACC patients using RNA-sequencing and quantitative real-time PCR analysis. Differences in global gene expression between MYB TSS2 high and low cases were studied, and pathway analyses were performed.

RESULTS

MYB TSS2 activity was significantly higher in ACC metastases than in primary tumors (median activity 15.1 vs 3.0, P = 0.0003). MYB TSS2 high ACC metastases showed a specific gene expression signature, including increased expression of multi-drug resistance genes and canonical MYB target genes, and suppression of the p53 and NOTCH pathways.

CONCLUSIONS

Collectively, our findings indicate that elevated MYB TSS2 activity is associated with metastases, potential drug resistance, and augmented MYB-driven gene expression in ACC. Our study advocates the need for new therapies that specifically target MYB and drug resistance mechanisms in disseminated ACC.

Survival and Quality of Life after Isolated Hepatic Perfusion with Melphalan as a Treatment for Uveal Melanoma Liver Metastases - Final Results from the Phase III Randomized Controlled Trial SCANDIUM

OBJECTIVE

To investigate overall survival (OS) and health-related quality of life (HRQOL) of first-line isolated hepatic perfusion (IHP) compared to best alternative care (BAC) for patients with uveal melanoma liver metastases.

SUMMARY BACKGROUND DATA

Approximately half of patients with uveal melanoma develop metastatic disease, most commonly in the liver and systemic treatment options are limited. Isolated hepatic perfusion (IHP) is a locoregional therapy with high response rates but with unclear effect on overall survival (OS).

METHODS

In this phase III randomized controlled multicenter trial (the SCANDIUM trial) patients with previously untreated isolated uveal melanoma liver metastases were included between 2013-2021, with at least 24 months of follow-up. The planned accrual was 90 patients randomized 1:1 to receive a one-time treatment with IHP or BAC. Crossover to IHP was not allowed. The primary endpoint was the 24-month OS rate, with the hypothesis of a treatment effect leading to a 50% OS rate in the IHP group compared to 20% in the control group. HRQOL was measured by the EuroQol 5-domains 3-levels (EQ-5D-3L) questionnaire over 12 months.

RESULTS

The intention-to-treat (ITT) population included 87 patients randomized to the IHP group (43 patients; 41 [89%] received IHP) or the control group (44 patients). The control group received chemotherapy (49%), immunotherapy (39%), or localized interventions (9%). In the ITT population, the median PFS was 7.4 months in the IHP group compared with 3.3 months in the control group, with a hazard ratio of 0.21 (95% CI, 0.12-0.36). The 24-month OS rate was 46.5% in the IHP group versus 29.5% in the control group (P=0.12). The median OS was 21.7 months versus 17.6 months, with a hazard ratio of 0.64 (95% CI, 0.37-1.10). EQ-5D-3L showed a sustained high health status for the IHP group over 12 months, compared to a deteriorating trend in the control group.

CONCLUSIONS

For patients with liver metastases from uveal melanoma, IHP offers high response rates translating to a benefit in PFS including a trend of better HRQOL compared to the control group. However, the primary endpoint of OS at 24 months was not met.

Isolated Hepatic Perfusion With Melphalan for Patients With Isolated Uveal Melanoma Liver Metastases: A Multicenter, Randomized, Open-Label, Phase III Trial (the SCANDIUM Trial)

PURPOSE

About half of patients with metastatic uveal melanoma present with isolated liver metastasis, in whom the median survival is 6-12 months. The few systemic treatment options available only moderately prolong survival. Isolated hepatic perfusion (IHP) with melphalan is a regional treatment option, but prospective efficacy and safety data are lacking.

METHODS

In this multicenter, randomized, open-label, phase III trial, patients with previously untreated isolated liver metastases from uveal melanoma were randomly assigned to receive a one-time treatment with IHP with melphalan or best alternative care (control group). The primary end point was overall survival at 24 months. Here, we report the secondary outcomes of response according to RECIST 1.1 criteria, progression-free survival (PFS), hepatic PFS (hPFS), and safety.

RESULTS

Ninety-three patients were randomly assigned, and 87 patients were assigned to either IHP (n = 43) or a control group receiving the investigator's choice of treatment (n = 44). In the control group, 49% received chemotherapy, 39% immune checkpoint inhibitors, and 9% locoregional treatment other than IHP. In an intention-to-treat analysis, the overall response rates (ORRs) were 40% versus 4.5% in the IHP and control groups, respectively (P < .0001). The median PFS was 7.4 months versus 3.3 months (P < .0001), with a hazard ratio of 0.21 (95% CI, 0.12 to 0.36), and the median hPFS was 9.1 months versus 3.3 months (P < .0001), both favoring the IHP arm. There were 11 treatment-related serious adverse events in the IHP group compared with seven in the control group. There was one treatment-related death in the IHP group.

CONCLUSION

IHP treatment resulted in superior ORR, hPFS, and PFS compared with best alternative care in previously untreated patients with isolated liver metastases from primary uveal melanoma.

Chemokine Analysis in Patients with Metastatic Uveal Melanoma Suggests a Role for CCL21 Signaling in Combined Epigenetic Therapy and Checkpoint Immunotherapy

Purpose

Patients with metastatic uveal melanoma have limited therapeutic options and high mortality rate so new treatment options are needed.

Patients and Methods

We previously reported that patients treated with the PD-1 inhibitor pembrolizumab and the histone deacetylase inhibitor entinostat in the PEMDAC trial, experienced clinical benefits if their tumor originated from iris or was wildtype for BAP1 tumor suppressor gene. Here we present the 2-year follow-up of the patients in the PEMDAC trial and identify additional factors that correlate with response or survival.

Results

Durable responses were observed in 4 patients, with additional 8 patients exhibiting a stable disease. The median overall survival was 13.7 months. Grade 3 adverse events were reported in 62% of the patients, but they were all manageable. No fatal toxicity was observed. Activity of thymidine kinase 1 in plasma was higher in patients with stable disease or who progressed on treatment, compared with those with partial response. Chemokines and cytokines were analyzed in plasma. Three chemokines were significantly different when comparing patients with and without response. One of the factors, CCL21, was higher in the plasma of responding patients before treatment initiation but decreased in the same patients upon treatment. In tumors, CCL21 was expressed in areas resembling tertiary lymphoid structures (TLS). High plasma levels of CCL21 and presence of TLS-like regions in the tumor correlated with longer survival.

Conclusions

This study provides insight into durable responses in the PEMDAC trial, and describes dynamic changes of chemokines and cytokines in the blood of these patients.

Significance

The most significant finding from the 2-year follow-up study of the PEMDAC trial was that high CCL21 levels in blood was associated with response and survival. CCL21 was also expressed in TLS-like regions and presence of these regions was associated with longer survival. These analyses of soluble and tumor markers can inform on predictive biomarkers needing validation and become hypothesis generating for experimental research.

Treatment with Anti-HER2 Chimeric Antigen Receptor Tumor-Infiltrating Lymphocytes (CAR-TILs) Is Safe and Associated with Antitumor Efficacy in Mice and Companion Dogs

Patients with metastatic melanoma have a historically poor prognosis, but recent advances in treatment options, including targeted therapy and immunotherapy, have drastically improved the outcomes for some of these patients. However, not all patients respond to available treatments, and around 50% of patients with metastatic cutaneous melanoma and almost all patients with metastases of uveal melanoma die of their disease. Thus, there is a need for novel treatment strategies for patients with melanoma that do not benefit from the available therapies. Chimeric antigen receptor-expressing T (CAR-T) cells are largely unexplored in melanoma. Traditionally, CAR-T cells have been produced by transducing blood-derived T cells with a virus expressing CAR. However, tumor-infiltrating lymphocytes (TILs) can also be engineered to express CAR, and such CAR-TILs could be dual-targeting. To this end, tumor samples and autologous TILs from metastasized human uveal and cutaneous melanoma were expanded in vitro and transduced with a lentiviral vector encoding an anti-HER2 CAR construct. When infused into patient-derived xenograft (PDX) mouse models carrying autologous tumors, CAR-TILs were able to eradicate melanoma, even in the absence of antigen presentation by HLA. To advance this concept to the clinic and assess its safety in an immune-competent and human-patient-like setting, we treated four companion dogs with autologous anti-HER2 CAR-TILs. We found that these cells were tolerable and showed signs of anti-tumor activity. Taken together, CAR-TIL therapy is a promising avenue for broadening the tumor-targeting capacity of TILs in patients with checkpoint immunotherapy-resistant melanoma.

SARS-CoV-2 replicates and displays oncolytic properties in clear cell and papillary renal cell carcinoma

The SARS-CoV-2 virus is currently causing a global pandemic. Infection may result in a systemic disease called COVID-19, affecting primarily the respiratory tract. Often the gastrointestinal tract and kidneys also become involved. Angiotensin converting enzyme 2 (ACE2) serves as the receptor for SARS-CoV-2. The membrane proteins, Transmembrane serine protease 2 (TMPRSS2) and Neuropilin 1 (NRP1) are accessory proteins facilitating the virus entry. In this study we show that the human proximal kidney tubules, express these factors. We hypothesized that cancers derived from proximal tubules as clear cell (CCRCC) and papillary renal cell carcinoma (PRCC), retain the expression of the SARS-CoV-2 entry factors making these cancers susceptible to SARS-CoV-2 infection. We used bioinformatics, western blotting, and assessment of tissue micro arrays (TMA) including 263 cases of CCRCC, 139 cases of PRCC and 18 cases of chromophobe RCC to demonstrate that the majority of CCRCC and PRCC cases retained the RNA and protein expression of the entry factors for SARS-CoV-2. We furthermore show that SARS-CoV-2 virus propagated robustly in primary cultures of CCRCC and PRCC cells with a visible virus cytopathogenic effect correlating with viral RNA expression levels. We also noted that the delta-variant of SARS-CoV-2 causes cancer cells to form syncytia in-vitro. This phenomenon was also identified histologically in CCRCC tissue from a patient that had been hospitalized for COVID-19, twelve months prior to nephrectomy. Our data provide insights into SARS-CoV-2 infectivity in renal cell carcinoma and that the virus causes a distinct cytopathogenic effect.

Epigenetic therapy to enhance therapeutic effects of PD-1 inhibition in therapy-resistant melanoma

Targeted therapy and immunotherapy have revolutionized the treatment of metastatic skin melanoma but around half of all patients develop resistance early or late during treatment. The situation is even worse for patients with metastatic uveal melanoma (UM). Here we hypothesized that the immunotherapy of therapy-resistant skin melanoma or UM can be enhanced by epigenetic inhibitors. Cultured B16F10 cells and human UM cells were treated with the histone deacetylase inhibitor (HDACi) entinostat or BETi JQ1. Entinostat-induced HLA expression and PD-L1, but JQ1 did not. A syngeneic mouse model carrying B16-F10 melanoma cells was treated with PD-1 and CTLA4 inhibitors, which was curative. Co-treatment with the bioavailable BETi iBET726 impaired the immunotherapy effect. Monotherapy of a B16-F10 mouse model with anti-PD-1 resulted in a moderate therapeutic effect that could be enhanced by entinostat. Mice carrying PD-L1 knockout B16-F10 cells were also sensitive to entinostat. This suggests HDAC inhibition and immunotherapy could work in concert. Indeed, co-cultures of UM with HLA-matched melanoma-specific tumor-infiltrating lymphocytes (TILs) resulted in higher TIL-mediated melanoma killing when entinostat was added. Further exploration of combined immunotherapy and epigenetic therapy in metastatic melanoma resistant to PD-1 inhibition is warranted.

Isolated hepatic perfusion as a treatment for uveal melanoma liver metastases, first results from a phase III randomized controlled multicenter trial (the SCANDIUM trial)

LBA9509

Background: Uveal melanoma is the most common primary intraocular malignancy in adults. Despite successful control of the primary tumor, metastatic disease will ultimately develop in approximately 50% of the patients, with the liver being the most common site. The median survival for patients with liver metastases is about 6-12 months, and there are only few systemic treatment options available that moderately prolong survival. A previous trial using isolated hepatic perfusion (IHP) has suggested a 14-month increase in overall survival, compared with a historical control group consisting of the longest surviving patients in Sweden during the same time period (26 vs. 12 months). Methods: In this multicenter randomized, controlled, phase III trial, patients with previously untreated isolated liver metastasis from uveal melanoma were randomized between 2013 and 2021 to receive IHP or best alternative care (control group). The primary end point is overall survival at 24 months, but here we report the secondary outcomes of response according to RECIST 1.1 criteria, progression-free survival (PFS), hepatic PFS (hPFS) and toxicity. Results: A total of 93 patients were randomized, with three patients in each group being excluded due to either withdrawal of consent or inappropriate enrollment, and a total of 87 patients were assigned to either IHP group (43 patients) or control group (44 patients). In the IHP group, 41 (89%) patients were treated per protocol, and in the control group, 49% of the patients were treated with chemotherapy, 39% with immunotherapy and 9% with localized treatment interventions. In an intention-to-treat analysis, the overall response rate (ORR) in the IHP group was 40% (17/43) compared to 4.5% (2/44) in the control group (p<0.0001). The median hPFS in the IHP group was 9.1 months (95% CI, 5.6 to 13.4 months), compared to 3.3 months (95% CI, 2.9 to 4.0 months) in the control group (p<0.0001). The median PFS in the IHP group was 7.4 months (95% CI, 5.2 to 11.6 months), compared to 3.3 months (95% CI, 2.9 to 3.7 months) in the control group (p<0.0001). There were 14 treatment-related serious adverse events in the IHP group, where vascular complication and infections were the most common side effects, compared to 13 in the control group where immunotherapy related side effects were most common. There was one treatment related death in the IHP group. Conclusions: Treatment with IHP resulted in superior ORR, hPFS and PFS compared to best alternative care among previously untreated patients with isolated uveal melanoma liver metastasis. Clinical trial information: NCT01785316.

Intussusceptive Angiogenesis in Human Metastatic Malignant Melanoma

Angiogenesis supplies oxygen and nutrients to growing tumors. Inhibiting angiogenesis may stop tumor growth, but vascular endothelial growth factor inhibitors have limited effect in most tumors. This limited effect may be explained by an additional, less vascular endothelial growth factor-driven form of angiogenesis known as intussusceptive angiogenesis. The importance of intussusceptive angiogenesis in human tumors is not known. Epifluorescence and confocal microscopy was used to visualize intravascular pillars, the hallmark structure of intussusceptive angiogenesis, in tumors. Human malignant melanoma metastases, patient-derived melanoma xenografts in mice (PDX), and genetically engineered v-raf murine sarcoma viral oncogene homolog B1 (BRAF)-induced, phosphatase and TENsin homolog deleted on chromosome 10 (PTEN)-deficient (BPT) mice (BrafCA/+Ptenf/fTyr-Cre+/0-mice) were analyzed for pillars. Gene expression in human melanoma metastases and PDXs was analyzed by RNA sequencing. Matrix metalloproteinase 9 (MMP9) protein expression and T-cell and macrophage infiltration in tumor sections were determined with multiplex immunostaining. Intravascular pillars were detected in human metastases but rarely in PDXs and not in BPT mice. The expression of MMP9 mRNA was higher in human metastases compared with PDXs. High expression of MMP9 protein as well as infiltration of macrophages and T-cells were detected in proximity to intravascular pillars. MMP inhibition blocked formation of pillars, but not tubes or tip cells, in vitro. In conclusion, intussusceptive angiogenesis may contribute to the growth of human melanoma metastases. MMP inhibition blocked pillar formation in vitro and should be further investigated as a potential anti-angiogenic drug target in metastatic melanoma.

The PEMDAC phase 2 study of pembrolizumab and entinostat in patients with metastatic uveal melanoma

Preclinical studies have suggested that epigenetic therapy could enhance immunogenicity of cancer cells. We report the results of the PEMDAC phase 2 clinical trial (n = 29; NCT02697630) where the HDAC inhibitor entinostat was combined with the PD-1 inhibitor pembrolizumab in patients with metastatic uveal melanoma (UM). The primary endpoint was objective response rate (ORR), and was met with an ORR of 14%. The clinical benefit rate at 18 weeks was 28%, median progression free survival was 2.1 months and the median overall survival was 13.4 months. Toxicities were manageable, and there were no treatment-related deaths. Objective responses and/or prolonged survival were seen in patients with BAP1 wildtype tumors, and in one patient with an iris melanoma that exhibited a UV signature. Longer survival also correlated with low baseline ctDNA levels or LDH. In conclusion, HDAC inhibition and anti-PD1 immunotherapy results in durable responses in a subset of patients with metastatic UM.Trial registration ClinicalTrials.gov registration number: NCT02697630 (registered 3 March 2016). EudraCT registration number: 2016-002114-50.

Discovery of a rare GKAP1-NTRK2 fusion in a pediatric low-grade glioma, leading to targeted treatment with TRK-inhibitor larotrectinib

Here we report a case of an 11-year-old girl with an inoperable tumor in the optic chiasm/hypothalamus, who experienced several tumor progressions despite three lines of chemotherapy treatment. Routine clinical examination classified the tumor as a BRAF-negative pilocytic astrocytoma. Copy-number variation profiling of fresh frozen tumor material identified two duplications in 9q21.32–33 leading to breakpoints within the GKAP1 and NTRK2 genes. RT-PCR Sanger sequencing revealed a GKAP1-NTRK2 exon 10–16 in-frame fusion, generating a putative fusion protein of 658 amino acids with a retained tyrosine kinase (TK) domain. Functional analysis by transient transfection of HEK293 cells showed the GKAP1-NTRK2 fusion protein to be activated through phosphorylation of the TK domain (Tyr705). Subsequently, downstream mediators of the MAPK- and PI3K-signaling pathways were upregulated in GKAP1-NTRK2 cells compared to NTRK2 wild-type; phosphorylated (p)ERK (3.6-fold), pAKT (1.8- fold), and pS6 ribosomal protein (1.4-fold). Following these findings, the patient was enrolled in a clinical trial and treated with the specific TRK-inhibitor larotrectinib, resulting in the arrest of tumor growth. The patient’s condition is currently stable and the quality of life has improved significantly. Our findings highlight the value of comprehensive clinical molecular screening of BRAF-negative pediatric low-grade gliomas, to reveal rare fusions serving as targets for precision therapy.

BET bromodomain inhibitor HMBA synergizes with MEK inhibition in treatment of malignant glioma

(1) Background: BET bromodomain proteins regulate transcription by binding acetylated histones and attracting key factors for, e.g., transcriptional elongation. BET inhibitors have been developed to block pathogenic processes such as cancer and inflammation. Despite having potent biological activities, BET inhibitors have still not made a breakthrough in clinical use for treating cancer. Multiple resistance mechanisms have been proposed but thus far no attempts to block this in glioma has been made. (2) Methods: Here, we have conducted a pharmacological synergy screen in glioma cells to search for possible combination treatments augmenting the apoptotic response to BET inhibitors. We first used HMBA, a compound that was developed as a differentiation therapy four decades ago but more recently was shown to primarily inhibit BET bromodomain proteins. Data was also generated using other BET inhibitors. (3) Results: In the synergy screen, we discovered that several MEK inhibitors can enhance apoptosis in response to HMBA in rat and human glioma cells in vitro as well as in vivo xenografts. The combination is not unique to HMBA but also other BET inhibitors such as JQ1 and I-BET-762 can synergize with MEK inhibitors. (4) Conclusions: Our findings validate a combination therapy previously demonstrated to exhibit anti-cancer activities in multiple other tumour types but which appears to have been lost in translation to the clinic.

Small molecule inhibitors and a kinase-dead expressing mouse model demonstrate that the kinase activity of Chk1 is essential for mouse embryos and cancer cells

The study use small molecule inhibitors and a kinase-dead expressing mouse model to demonstrate that the kinase activity of Chk1 is essential for mouse embryos and cancer cells.

Chk1 kinase is downstream of the ATR kinase in the sensing of improper replication. Previous cell culture studies have demonstrated that Chk1 is essential for replication. Indeed, Chk1 inhibitors are efficacious against tumors with high-level replication stress such as Myc-induced lymphoma cells. Treatment with Chk1 inhibitors also combines well with certain chemotherapeutic drugs, and effects associate with the induction of DNA damage and reduction of Chk1 protein levels. Most studies of Chk1 function have relied on the use of inhibitors. Whether or not a mouse or cancer cells could survive if a kinase-dead form of Chk1 is expressed has not been investigated before. Here, we generate a mouse model that expresses a kinase-dead (D130A) allele in the mouse germ line. We find that this mouse is overtly normal and does not have problems with erythropoiesis with aging as previously been shown for a mouse expressing one null allele. However, similar to a null allele, homozygous kinase-dead mice cannot be generated, and timed pregnancies of heterozygous mice suggest lethality of homozygous blastocysts at around the time of implantation. By breeding the kinase-dead Chk1 mouse with a conditional allele, we are able to demonstrate that expression of only one kinase-dead allele, but no wild-type allele, of Chek1 is lethal for Myc-induced cancer cells. Finally, treatment of melanoma cells with tumor-infiltrating T cells or CAR-T cells is effective even if Chk1 is inhibited, suggesting that Chk1 inhibitors can be safely administered in patients where immunotherapy is an essential component of the arsenal against cancer.

Molecular profiling of driver events in metastatic uveal melanoma

Metastatic uveal melanoma is less well understood than its primary counterpart, has a distinct biology compared to skin melanoma, and lacks effective treatments. Here we genomically profile metastatic tumors and infiltrating lymphocytes. BAP1 alterations are overrepresented and found in 29/32 of cases. Reintroducing a functional BAP1 allele into a deficient patient-derived cell line, reveals a broad shift towards a transcriptomic subtype previously associated with better prognosis of the primary disease. One outlier tumor has a high mutational burden associated with UV-damage. CDKN2A deletions also occur, which are rarely present in primaries. A focused knockdown screen is used to investigate overexpressed genes associated withcopy number gains. Tumor-infiltrating lymphocytes are in several cases found tumor-reactive, but expression of the immune checkpoint receptors TIM-3, TIGIT and LAG3 is also abundant. This study represents the largest whole-genome analysis of uveal melanoma to date, and presents an updated view of the metastatic disease.

Correction: A patient-derived xenograft pre-clinical trial reveals treatment responses and a resistance mechanism to karonudib in metastatic melanoma

On Pubmed, the name of co-author Roger Olofsson Bagge appeared incorrectly as "Bagge RO" instead of "Olofsson Bagge, Roger". This has been corrected in the PDF and HTML versions.

Concomitant use of pembrolizumab and entinostat in adult patients with metastatic uveal melanoma (PEMDAC study): protocol for a multicenter phase II open label study

BACKGROUND

While recent years have seen a revolution in the treatment of metastatic cutaneous melanoma, no treatment has yet been able to demonstrate any prolonged survival in metastatic uveal melanoma. Thus, metastatic uveal melanoma remains a disease with an urgent unmet medical need. Reports of treatment with immune checkpoint inhibitors have thus far been disappointing. Based on animal experiments, it is reasonable to hypothesize that the effect of immunotherapy may be augmented by epigenetic therapy. Proposed mechanisms include enhanced expression of HLA class I and cancer antigens on cancer cells, as well as suppression of myeloid suppressor cells.

METHODS

The PEMDAC study is a multicenter, open label phase II study assessing the efficacy of concomitant use of the PD1 inhibitor pembrolizumab and the class I HDAC inhibitor entinostat in adult patients with metastatic uveal melanoma. Primary endpoint is objective response rate. Eligible patients have histologically confirmed metastatic uveal melanoma, ECOG performance status 0-1, measurable disease as per RECIST 1.1 and may have received any number of prior therapies, with the exception of anticancer immunotherapy. Twenty nine patients will be enrolled. Patients receive pembrolizumab 200 mg intravenously every third week in combination with entinostat 5 mg orally once weekly. Treatment will continue until progression of disease or intolerable toxicity or for a maximum of 24 months.

DISCUSSION

The PEMDAC study is the first trial to assess whether the addition of an HDAC inhibitor to anti-PD1 therapy can yield objective anti-tumoral responses in metastatic UM.

TRIAL REGISTRATION

ClinicalTrials.gov registration number: NCT02697630 . (Registered 3 March 2016). EudraCT registration number: 2016-002114-50.

HER2 CAR-T Cells Eradicate Uveal Melanoma and T-cell Therapy-Resistant Human Melanoma in IL2 Transgenic NOD/SCID IL2 Receptor Knockout Mice

Chimeric antigen receptors (CAR) can transmit signals akin to those from activated T-cell receptors when bound to a cell surface target. CAR-expressing T cells against CD19 can cause curative effects in leukemia and lymphoma and is approved for clinical use. However, no CAR-T therapy is currently approved for use in solid tumors. We hypothesize that the resistance of solid tumors to CAR-T can be overcome by similar means as those used to reactivate tumor-infiltrating T lymphocytes (TIL), for example, by cytokines or immune checkpoint blockade. Here we demonstrate that CAR-T cells directed against HER2 can kill uveal and cutaneous melanoma cells in vitro and in vivo. Curative effects in vivo were only observed in xenografts grown in a NOD/SCID IL2 receptor gamma (NOG) knockout mouse strain transgenic for human IL2. The effect was target-specific, as CRISPR/Cas9-mediated disruption of HER2 in the melanoma cells abrogated the killing effect of the CAR-T cells. The CAR-T cells were also able to kill melanoma cells from patients resistant to adoptive T-cell transfer (ACT) of autologous TILs. Thus, CAR-T therapy represents an option for patients that do not respond to immunotherapy with ACT of TIL or immune checkpoint blockade. In addition, our data highlight the use of IL2 transgenic NOG mice as models to prove efficacy of CAR-T-cell products, possibly even in a personalized manner. SIGNIFICANCE: These findings demonstrate that a novel humanized mouse model can help clinical translation of CAR-T cells against uveal and cutaneous melanoma that do not respond to TIL therapy or immune checkpoint blockade.

Response and Toxicity of Repeated Isolated Limb Perfusion (re-ILP) for Patients With In-Transit Metastases of Malignant Melanoma

BACKGROUND

Isolated limb perfusion (ILP) is a safe and well-established treatment for in-transit metastases of melanoma. In case of relapse or disease progression, ILP can be repeated (re-ILP). This study aimed retrospectively to analyze a large consecutive series of re-ILP and compare clinical outcomes with first-time ILP.

METHOD

Between 2001 and 2015, 290 consecutive patients underwent 380 ILPs. Of these, 90 were re-ILPs including 68 second ILPs, 16 third ILPs, 4 fourth ILPs, and two fifth ILPs. The study evaluated response (using World Health Organization [WHO] criteria), local toxicity (using the Wieberdink scale), and complications (using Clavien-Dindo).

RESULTS

The results were compared between the first ILP, the second ILP, and the third to fifth ILP. The overall response rate was respectively 83%, 80% and 68%, with a complete response (CR) rate of 60%, 41%, and 59%. In the re-ILP group, the patients with a CR after the first ILP had a 65% CR rate after the second ILP compared with 8% for the patients without a CR (p = 0.001). The risk for local toxicity or complications was not increased after re-ILP. The median overall survival periods were respectively 34, 41, and 93 months (p = 0.02).

CONCLUSION

As a therapeutic option, ILP can be repeated safely for in-transit metastases of melanoma, achieving similar high response rates without increasing complications or toxicity. Re-ILP is mainly indicated for patients who already had a CR after the first ILP, whereas other treatment options should be considered for primary non-responders.

Mutational Signature and Transcriptomic Classification Analyses as the Decisive Diagnostic Tools for a Cancer of Unknown Primary

Purpose

Cancer of unknown primary is a group of metastatic tumors in which the standard diagnostic workup fails to identify the site of origin of the tumor. The potential impact of precision oncology on this group of patients is large, because actionable driver mutations and a correct diagnosis could provide treatment options otherwise not available for patients with these fatal cancers. This study investigated if comprehensive genomic analyses could provide information on the origin of the tumor.

Patients and Methods

Here we describe a patient whose tumor was misdiagnosed at least three times. Next-generation sequencing, a patient-derived xenograft mouse model, and bioinformatics were used to identify an actionable mutation, predict resistance development to the targeted therapy, and correctly diagnose the origin of the tumor. Transcriptomic classification was benchmarked using The Cancer Genome Atlas (TCGA).

Results

Despite the lack of a known primary tumor site and the absence of diagnostic immunohistochemical markers, the origin of the patient’s tumor was established using the novel bioinformatic workflow. This included a mutational signature analysis of the sequenced metastases and comparison of their transcriptomic profiles to a pan-cancer panel of tumors from TCGA. We further discuss the strengths and limitations of the latter approaches in the context of three potentially incorrectly diagnosed TCGA lung tumors.

Conclusion

Comprehensive genomic analyses can provide information on the origin of tumors in patients with cancer of unknown primary.

A patient-derived xenograft pre-clinical trial reveals treatment responses and a resistance mechanism to karonudib in metastatic melanoma

Karonudib (TH1579) is a novel compound that exerts anti-tumor activities and has recently entered phase I clinical testing. The aim of this study was to conduct a pre-clinical trial in patient-derived xenografts to identify the possible biomarkers of response or resistance that could guide inclusion of patients suffering from metastatic melanoma in phase II clinical trials. Patient-derived xenografts from 31 melanoma patients with metastatic disease were treated with karonudib or a vehicle for 18 days. Treatment responses were followed by measuring tumor sizes, and the models were categorized in the response groups. Tumors were harvested and processed for RNA sequencing and protein analysis. To investigate the effect of karonudib on T-cell-mediated anti-tumor activities, tumor-infiltrating T cells were injected in mice carrying autologous tumors and the mice treated with karonudib. We show that karonudib has heterogeneous anti-tumor effect on metastatic melanoma. Thus, based on the treatment responses, we could divide the 31 patient-derived xenografts in three treatment groups: progression group (32%), suppression group (42%), and regression group (26%). Furthermore, we show that karonudib has anti-tumor effect, irrespective of major melanoma driver mutations. Also, we identify high expression of ABCB1, which codes for p-gp pumps as a resistance biomarker. Finally, we show that karonudib treatment does not hamper T-cell-mediated anti-tumor responses. These findings can be used to guide future use of karonudib in clinical use with a potential approach as precision medicine.

Anti-Leukemic Properties of Histamine in Monocytic Leukemia: The Role of NOX2

In patients with acute myeloid leukemia (AML), treatment with histamine dihydrochloride (HDC) and low-dose IL-2 (HDC/IL-2) in the post-chemotherapy phase has been shown to reduce the incidence of leukemic relapse. The clinical benefit of HDC/IL-2 is pronounced in monocytic forms of AML, where the leukemic cells express histamine type 2 receptors (H2R) and the NAPDH oxidase-2 (NOX2). HDC ligates to H2Rs to inhibit NOX2-derived formation of reactive oxygen species, but details regarding the anti-leukemic actions of HDC remain to be elucidated. Here, we report that human NOX2+ myelomonocytic/monocytic AML cell lines showed increased expression of maturation markers along with reduced leukemic cell proliferation after exposure to HDC in vitro. These effects of HDC were absent in corresponding leukemic cells genetically depleted of NOX2 (NOX2-/-). We also observed that exposure to HDC altered the expression of genes involved in differentiation and cell cycle progression in AML cells and that these effects required the presence of NOX2. HDC promoted the differentiation also of primary monocytic, but not non-monocytic, AML cells in vitro. In a xenograft model, immunodeficient NOG mice were inoculated with wild-type or NOX2-/- human monocytic AML cells and treated with HDC in vivo. The administration of HDC reduced the in vivo expansion of NOX2+/+, but not of NOX2-/- human monocytic AML cells. We propose that NOX2 may be a conceivable target in the treatment of monocytic AML.

Hypoxia-regulated gene expression explains differences between melanoma cell line-derived xenografts and patient-derived xenografts

Cell line-derived xenografts (CDXs) are an integral part of drug efficacy testing during development of new pharmaceuticals against cancer but their accuracy in predicting clinical responses in patients have been debated. Patient-derived xenografts (PDXs) are thought to be more useful for predictive biomarker identification for targeted therapies, including in metastatic melanoma, due to their similarities to human disease. Here, tumor biopsies from fifteen patients and ten widely-used melanoma cell lines were transplanted into immunocompromised mice to generate PDXs and CDXs, respectively. Gene expression profiles generated from the tumors of these PDXs and CDXs clustered into distinct groups, despite similar mutational signatures. Hypoxia-induced gene signatures and overexpression of the hypoxia-regulated miRNA hsa-miR-210 characterized CDXs. Inhibition of hsa-miR-210 with decoys had little phenotypic effect in vitro but reduced sensitivity to MEK1/2 inhibition in vivo, suggesting down-regulation of this miRNA could result in development of resistance to MEK inhibitors.

BET bromodomain inhibitors synergize with ATR inhibitors in melanoma

Metastatic malignant melanoma continues to be a challenging disease despite clinical translation of the comprehensive understanding of driver mutations and how melanoma cells evade immune attack. In Myc-driven lymphoma, efficacy of epigenetic inhibitors of the bromodomain and extra-terminal domain (BET) family of bromodomain proteins can be enhanced by combination therapy with inhibitors of the DNA damage response kinase ATR. Whether this combination is active in solid malignancies like melanoma, and how it relates to immune therapy, has not previously investigated. To test efficacy and molecular consequences of combination therapies cultured melanoma cells were used. To assess tumor responses to therapies in vivo we use patient-derived xenografts and B6 mice transplanted with B16F10 melanoma cells. Concomitant inhibition of BET proteins and ATR of cultured melanoma cells resulted in similar effects as recently shown in lymphoma, such as induction of apoptosis and p62, implicated in autophagy, senescence-associated secretory pathway and ER stress. In vivo, apoptosis and suppression of subcutaneous growth of patient-derived melanoma and B16F10 cells were observed. Our data suggest that ATRI/BETI combination therapies are effective in melanoma.

BRAFV600 inhibition alters the microRNA cargo in the vesicular secretome of malignant melanoma cells

The BRAF inhibitors vemurafenib and dabrafenib can be used to treat patients with metastatic melanomas harboring BRAFV600 mutations. Initial antitumoral responses are often seen, but drug-resistant clones with reactivation of the MEK-ERK pathway soon appear. Recently, the secretome of tumor-derived extracellular vesicles (EVs) has been ascribed important functions in cancers. To elucidate the possible functions of EVs in BRAF-mutant melanoma, we determined the RNA content of the EVs, including apoptotic bodies, microvesicles, and exosomes, released from such cancer cells after vemurafenib treatment. We found that vemurafenib significantly increased the total RNA and protein content of the released EVs and caused significant changes in the RNA profiles. RNA sequencing and quantitative PCR show that cells and EVs from vemurafenib-treated cell cultures and tumor tissues harvested from cell-derived and patient-derived xenografts harbor unique miRNAs, especially increased expression of miR-211-5p. Mechanistically, the expression of miR-211-5p as a result of BRAF inhibition was induced by increased expression of MITF that regulates the TRPM1 gene resulting in activation of the survival pathway. In addition, transfection of miR-211 in melanoma cells reduced the sensitivity to vemurafenib treatment, whereas miR-211-5p inhibition in a vemurafenib resistant cell line affected the proliferation negatively. Taken together, our results show that vemurafenib treatment induces miR-211-5p up-regulation in melanoma cells both in vitro and in vivo, as well as in subsets of EVs, suggesting that EVs may provide a tool to understand malignant melanoma progression.

Abstract 5435: Beta-3 adrenergic antagonism can alleviate energy wasting associated with cancer-induced cachexia

Introduction: Cancer-associated cachexia (CAC) is a wasting syndrome characterized by atrophy of adipose tissue and skeletal muscle as a consequence of cancer. CAC has been shown to be responsible for approximately 20% of cancer deaths alone and reduces tolerance to treatment. The pathological mechanisms underlying this syndrome remains elusive and the treatment options are scarce. One proposed mechanism is the tumor-induced activation of brown adipose tissue (BAT); a thermogenic organ that wastes energy by producing heat via activation of uncoupling protein 1 (UCP1). β3 adrenergic signaling is a strong activator of BAT and the browning of white adipose tissue (WAT). We hypothesized that treatment with a specific β3 antagonist could alleviate CAC.

Method: To study cachexia, the LuCAP 32 xenograft model of human prostate cancer was utilized in immunodeficient balb/ca nude mice. After two weeks of tumor growth, treatment with the specific β3 antagonist SR59230A (SR) was started using subcutaneous micro osmotic pumps. Vehicle substance and nontumor bearing (NTB) mice were used as controls. The mice were sacrificed after a treatment period of four weeks and tissues were harvested for subsequent analysis. The PCR analysis was normalized to NTB mice.

Results: The mice with tumor started losing weight 20 days after tumor implantation while the nontumor bearing controls gained weight throughout the experiment. The group treated with SR also lost weight but to a significantly lesser degree than vehicle treated animals (-1.7 vs -3.2 g, p=0.032). This was also seen when looking at individual fat depots. Whole body composition, measured by echo MRI, showed that all groups equally lost fat mass over time. However, lean mass in the vehicle group decreased whereas the SR group gained lean mass (-0.41 vs 1.18 g, p=0.036). With respect to total body weight this gain in lean mass was counteracted by the loss of fat mass. PCR analysis of subcutaneous WAT showed a significant decrease in expression of ATGL (2.84 vs 1.98 FC, p=0,006), PPARγ (2.33 vs 1.45 FC, p=0.026) and CD36 (2.11 vs 1.3 FC, p=0.008) for the SR group compared to vehicle, indicating a decreased lipolysis and influx of fatty acids to WAT. The SR treated mice also had a significantly lower expression of UCP1 in WAT compared to controls (2.23 vs 0.58 FC, p=0.023), supporting the notion that the browning of WAT is a driving force for CAC.

Conclusion: Our data show that treatment with a specific β3 adrenergic antagonist alleviates CAC through decreased lipolysis of WAT and decreases the expression of markers for WAT browning. This indicates a correlation between decreased browning and severity of CAC. We also provide evidence that β3 antagonism helps preserve muscle mass, which is of major importance for treatment of CAC and something that few other treatment options have been able to show.

Citation Format: Fredrick Anderson, Stefan K. Nilsson, Jonas A. Nilsson. Beta-3 adrenergic antagonism can alleviate energy wasting associated with cancer-induced cachexia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5435. doi:10.1158/1538-7445.AM2017-5435

Acquired Immune Resistance Follows Complete Tumor Regression without Loss of Target Antigens or IFNγ Signaling

Cancer immunotherapy can result in durable tumor regressions in some patients. However, patients who initially respond often experience tumor progression. Here, we report mechanistic evidence of tumoral immune escape in an exemplary clinical case: a patient with metastatic melanoma who developed disease recurrence following an initial, unequivocal radiologic complete regression after T-cell-based immunotherapy. Functional cytotoxic T-cell responses, including responses to one mutant neoantigen, were amplified effectively with therapy and generated durable immunologic memory. However, these immune responses, including apparently effective surveillance of the tumor mutanome, did not prevent recurrence. Alterations of the MHC class I antigen-processing and presentation machinery (APM) in resistant cancer cells, but not antigen loss or impaired IFNγ signaling, led to impaired recognition by tumor-specific CD8⁺ T cells. Our results suggest that future immunotherapy combinations should take into account targeting cancer cells with intact and impaired MHC class I-related APM. Loss of target antigens or impaired IFNγ signaling does not appear to be mandatory for tumor relapse after a complete radiologic regression. Personalized studies to uncover mechanisms leading to disease recurrence within each individual patient are warranted. Cancer Res; 77(17); 4562-6. ©2017 AACR.

Predictors of work disability after start of anti-TNF therapy in a national cohort of Swedish patients with rheumatoid arthritis: does early anti-TNF therapy bring patients back to work?

OBJECTIVES

To examine predictors of work ability gain and loss after anti-tumour necrosis factor (TNF) start, respectively, in working-age patients with rheumatoid arthritis (RA) with a special focus on disease duration.

METHODS

Patients with RA, aged 19-62 years, starting their first TNF inhibitor 2006-2009 with full work ability (0 sick leave/disability pension days during 3 months before bio-start; n=1048) or no work ability (90 days; n=753) were identified in the Swedish biologics register (Anti-Rheumatic Treatment In Sweden, ARTIS) and sick leave/disability pension days retrieved from the Social Insurance Agency. Outcome was defined as work ability gain ≥50% for patients without work ability at bio-start and work ability loss ≥50% for patients with full work ability, and survival analyses conducted. Baseline predictors including disease duration, age, sex, education level, employment, Health Assessment Questionnaire, Disease Activity Score 28 and relevant comorbidities were estimated using Cox regression.

RESULTS

During 3 years after anti-TNF start, the probability of regaining work ability for totally work-disabled patients was 35% for those with disease duration <5 years and 14% for disease duration ≥5 years (adjusted HR 2.1 (95% CI 1.4 to 3.2)). For patients with full work ability at bio-start, disease duration did not predict work ability loss. Baseline disability pension was also a strong predictor of work ability gain after treatment start.

CONCLUSIONS

A substantial proportion of work-disabled patients with RA who start anti-TNF therapy regain work ability. Those initiating treatment within 5 years of symptom onset have a more than doubled 3-year probability of regaining work ability compared with later treatment starts. This effect seems largely due to the impact of disease duration on disability pension status.

Complement peptide C3a stimulates neural plasticity after experimental brain ischaemia

Ischaemic stroke induces endogenous repair processes that include proliferation and differentiation of neural stem cells and extensive rewiring of the remaining neural connections, yet about 50% of stroke survivors live with severe long-term disability. There is an unmet need for drug therapies to improve recovery by promoting brain plasticity in the subacute to chronic phase after ischaemic stroke. We previously showed that complement-derived peptide C3a regulates neural progenitor cell migration and differentiation in vitro and that C3a receptor signalling stimulates neurogenesis in unchallenged adult mice. To determine the role of C3a-C3a receptor signalling in ischaemia-induced neural plasticity, we subjected C3a receptor-deficient mice, GFAP-C3a transgenic mice expressing biologically active C3a in the central nervous system, and their respective wild-type controls to photothrombotic stroke. We found that C3a overexpression increased, whereas C3a receptor deficiency decreased post-stroke expression of GAP43 (P < 0.01), a marker of axonal sprouting and plasticity, in the peri-infarct cortex. To verify the translational potential of these findings, we used a pharmacological approach. Daily intranasal treatment of wild-type mice with C3a beginning 7 days after stroke induction robustly increased synaptic density (P < 0.01) and expression of GAP43 in peri-infarct cortex (P < 0.05). Importantly, the C3a treatment led to faster and more complete recovery of forepaw motor function (P < 0.05). We conclude that C3a-C3a receptor signalling stimulates post-ischaemic neural plasticity and intranasal treatment with C3a receptor agonists is an attractive approach to improve functional recovery after ischaemic brain injury.

Validation and development of MTH1 inhibitors for treatment of cancer

BACKGROUND

Previously, we showed cancer cells rely on the MTH1 protein to prevent incorporation of otherwise deadly oxidised nucleotides into DNA and we developed MTH1 inhibitors which selectively kill cancer cells. Recently, several new and potent inhibitors of MTH1 were demonstrated to be non-toxic to cancer cells, challenging the utility of MTH1 inhibition as a target for cancer treatment.

MATERIAL AND METHODS

Human cancer cell lines were exposed in vitro to MTH1 inhibitors or depleted of MTH1 by siRNA or shRNA. 8-oxodG was measured by immunostaining and modified comet assay. Thermal Proteome profiling, proteomics, cellular thermal shift assays, kinase and CEREP panel were used for target engagement, mode of action and selectivity investigations of MTH1 inhibitors. Effect of MTH1 inhibition on tumour growth was explored in BRAF V600E-mutated malignant melanoma patient derived xenograft and human colon cancer SW480 and HCT116 xenograft models.

RESULTS

Here, we demonstrate that recently described MTH1 inhibitors, which fail to kill cancer cells, also fail to introduce the toxic oxidized nucleotides into DNA. We also describe a new MTH1 inhibitor TH1579, (Karonudib), an analogue of TH588, which is a potent, selective MTH1 inhibitor with good oral availability and demonstrates excellent pharmacokinetic and anti-cancer properties in vivo.

CONCLUSION

We demonstrate that in order to kill cancer cells MTH1 inhibitors must also introduce oxidized nucleotides into DNA. Furthermore, we describe TH1579 as a best-in-class MTH1 inhibitor, which we expect to be useful in order to further validate the MTH1 inhibitor concept.

Abstract 642: Hypoxia-regulated gene expression explains differences between cell line-derived xenografts and patient-derived xenografts

Cell line-derived xenografts (CDXs) are an integral part of drug efficacy testing during development of new pharmaceuticals against cancer but their accuracy in predicting clinical responses in patients have been debated. Patient-derived xenografts (PDXs) are thought to be more useful for predictive biomarker identification for targeted therapies, including metastatic melanoma, due to their similarities to human disease. Here, tumor biopsies from patients and ten widely-used melanoma cell lines were transplanted into immunocompromised mice to generate PDXs and CDXs, respectively. Gene expression profiles generated from the tumors of these PDXs and CDXs clustered into distinct groups, despite similar mutational signatures. Hypoxia-induced gene signatures and overexpression of the hypoxia-regulated miRNA hsa-miR-210 characterized CDXs. Inhibition of hsa-miR-210 with decoys had little phenotypic effect in vitro but resulted in reduced sensitivity to MEK1/2 inhibition in vivo, suggesting down-regulation of this miRNA could result in development of resistance to MEK inhibitors.

Citation Format: Joydeep Bhadury, Berglind O. Einarsdottir, Agnieszka Podraza, Roger Olofsson Bagge, Ulrika Stierner, Lars Ny, Marcela Dávila López, Jonas A. Nilsson. Hypoxia-regulated gene expression explains differences between cell line-derived xenografts and patient-derived xenografts. [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 642.

Cancer Differentiating Agent Hexamethylene Bisacetamide Inhibits BET Bromodomain Proteins

Agents that trigger cell differentiation are highly efficacious in treating certain cancers, but such approaches are not generally effective in most malignancies. Compounds such as DMSO and hexamethylene bisacetamide (HMBA) have been used to induce differentiation in experimental systems, but their mechanisms of action and potential range of uses on that basis have not been developed. Here, we show that HMBA, a compound first tested in the oncology clinic over 25 years ago, acts as a selective bromodomain inhibitor. Biochemical and structural studies revealed an affinity of HMBA for the second bromodomain of BET proteins. Accordingly, both HMBA and the prototype BET inhibitor JQ1 induced differentiation of mouse erythroleukemia cells. As expected of a BET inhibitor, HMBA displaced BET proteins from chromatin, caused massive transcriptional changes, and triggered cell-cycle arrest and apoptosis in Myc-induced B-cell lymphoma cells. Furthermore, HMBA exerted anticancer effects in vivo in mouse models of Myc-driven B-cell lymphoma. This study illuminates the function of an early anticancer agent and suggests an intersection with ongoing clinical trials of BET inhibitor, with several implications for predicting patient selection and response rates to this therapy and starting points for generating BD2-selective BET inhibitors. Cancer Res; 76(8); 2376-83. ©2016 AACR.

BET bromodomain inhibitors synergize with ATR inhibitors to induce DNA damage, apoptosis, senescence-associated secretory pathway and ER stress in Myc-induced lymphoma cells

Inhibiting the bromodomain and extra-terminal (BET) domain family of epigenetic reader proteins has been shown to have potent anti-tumoral activity, which is commonly attributed to suppression of transcription. In this study, we show that two structurally distinct BET inhibitors (BETi) interfere with replication and cell cycle progression of murine Myc-induced lymphoma cells at sub-lethal concentrations when the transcriptome remains largely unaltered. This inhibition of replication coincides with a DNA-damage response and enhanced sensitivity to inhibitors of the upstream replication stress sensor ATR in vitro and in mouse models of B-cell lymphoma. Mechanistically, ATR and BETi combination therapy cause robust transcriptional changes of genes involved in cell death, senescence-associated secretory pathway, NFkB signaling and ER stress. Our data reveal that BETi can potentiate the cell stress and death caused by ATR inhibitors. This suggests that ATRi can be used in combination therapies of lymphomas without the use of genotoxic drugs.

Abstract B26: BET and HDAC inhibitors induce similar genes and biological effects and synergize to kill in Myc-induced murine lymphoma

Bromodomain and extraterminal (BET) proteins bind acetylated proteins, including histones, and regulate transcription. Recently, BET inhibitors (BETi) have been developed that show promise as potent anti-cancer drugs against various solid and hematological malignancies. Here we show that the structurally novel and orally bioavailable BETi RVX2135 inhibits proliferation and induces apoptosis of lymphoma cells arising in Myc-transgenic mice, in vitro and in vivo. We find that BET inhibition exhibited broad transcriptional effects in Myc-transgenic lymphoma cells affecting many transcription factor networks. By examining the genes induced by BETi, which have been largely ignored to date, we discovered that these were similar to those induced by histone deacetylase inhibitors (HDACi). HDACi also induced cell cycle arrest and cell death of Myc-induced murine lymphoma cells and synergized with BETi. To date many of the effects of BETi have been attributed to transcriptional suppression of genes like the MYC oncogene. Moreover, global profiling of the expression of miRNAs demonstrated that HDACi and BETi exhibited a very similar miRNA transcriptome. We also show one of the possible mechanism which might leads to the similarity of induced genes by BETi and HDACi using ChIP-sequencing experiments. Finally, we unravel a genetic and functional link between BET proteins and histone deacetylases (HDAC) that opens up avenues for combination therapies against a variety of cancer.

Citation Format: Joydeep Bhadury, Lisa M. Nilsson, Muralidharan Veppil Somsundar, Lydia C. Green, Ulrich B. Keller, Kevin G. McLure, Jonas A. Nilsson. BET and HDAC inhibitors induce similar genes and biological effects and synergize to kill in Myc-induced murine lymphoma. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B26.

Abstract B44: Effects of BET bromodomain inhibitors on replication and cell cycle progression

Myc family of transcription factors are deregulated in most cancers and their expression projects a poor prognosis. Genetic and pharmacological inhibition of Myc and several Myc targets leads to tumor regression and apoptosis. Recently, inhibitors of BET Bromodomain proteins (BETi) were shown to have anti-tumor properties and this has been attributed to Myc down-regulation. Here we show that two structurally distinct BETi affects replication and cell cycle progression at low concentrations where the transcriptome remains largely unaltered. Thymidine incorporation and flow cytometry analyses demonstrates that S-phase progression is hindered at these concentrations. However, in a cell-free system replication is not impaired suggesting that BETi-mediated block of replication is linked to effects on chromatin. Furthermore, at higher concentration of BETi, S-phase entry of cells is completely abrogated. Ectopic expression of Myc fails to rescue these phenotypes, suggesting a novel function of BET bromodomain proteins in replication and cell cycle regulation. Our pharmacogenetic screen in the presence of sub-lethal doses of BETi has identified several small molecule inhibitors to synergize with BETi to enhance apoptosis of Myc driven tumors.

Citation Format: Somsundar Veppil Muralidharan, Joydeep Bhadury, Lydia Green, Lisa M. Nilsson, Kevin G. McLure, Jonas A. Nilsson. Effects of BET bromodomain inhibitors on replication and cell cycle progression. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B44.

Abstract LB-053: Monitoring rearrangement of EML4-ALK in blood platelets predicts outcome to crizotinib treatment in non-small-cell lung cancer patients

Background: Novel targeted therapies have been successfully used against subgroups of non-small-cell lung cancer (NSCLC) patients, however, despite initial good response the cancer will eventually relapse. One of those subgroups harbors a rearranged EML4-ALK fusion gene that makes them responsive to crizotinib treatment, but therapy resistance often soon occurs. Real-time monitoring of rearrangement status over the course of treatment will help identify patients showing therapy resistance, but monitoring through serial tumor biopsies has been an obstacle. Therefore, new blood-based ´liquid biopsy´ platforms need to be developed to monitoring biomarkers in the circulation. Here we present one platform using the ability of platelets to sequester RNA released by tumor cells and represent an attractive source for non-invasive biomarker assessment.

Methods: EML4-ALK rearrangements were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) in platelets and plasma isolated from blood obtained from 77 NSCLC patients, 38 of whom had EML4-ALK-rearranged tumors. In a subset patients (n = 29) that were treated with crizotinib, progression-free survival (PFS) and overall survival (OS) were correlated with presence of EML4-ALK rearrangements in platelets.

Results: The study was designed with three parallel objectives: firstly to determine the sensitivity and specificity of detecting EML4-ALK rearrangements in platelets; secondly, to examine the potential impact of EML4-ALK rearrangement in platelets on outcome to crizotinib; thirdly, to test the feasibility of monitoring patients throughout treatment with EML4-ALK rearrangement assessment in platelets. Detection of EML4-ALK rearrangements in platelets demonstrated 65% sensitivity and 100% specificity. The PFS in patients treated with crizotinib was 3.7 months in patients with a positive EML4-ALK platelet status compared to 16 months for a negative EML4-ALK status (hazard ratio, 3.5; P = 0.02). Furthermore, longitudinal monitoring of EML4-ALK rearrangements in platelets was feasible, as demonstrated in an index patient where crizotinib resistance was observed two months prior to radiographic disease progression.

Conclusions: Platelets may provide a useful source for non-invasive assessment of EML4-ALK rearrangements and may prove useful for predicting outcome to crizotinib. Serial analyses of EML4-ALK rearrangements in platelets may help improve clinical decisions based on radiographic imaging alone by detecting resistance to therapy sooner.

Citation Format: Jonas A. Nilsson, Niki Karachaliou, Pepijn Schellen, Ana Gimenez-Capitan, Jordi Berenguer, Cristina Teixido, Justine L. Kuiper, Esther Drees, Magda Grabowska, Marte van Keulen, Jihane M. Tannous, Danielle A.M. Heideman, Erik Thunnissen, Anne-Marie C. Dingemans, Santiago Viteri, Bakhos A. Tannous, Ana Drozdowskyj, Rafael Rosell, Egbert F. Smit, Thomas Wurdinger. Monitoring rearrangement of EML4-ALK in blood platelets predicts outcome to crizotinib treatment in non-small-cell lung cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-053. doi:10.1158/1538-7445.AM2015-LB-053

Abstract B38: Melanoma patient-derived xenografts accurately models the disease and develop fast enough to guide treatment decisions

The development of novel therapies against melanoma would benefit from individualized tumor models to ensure the rapid and accurate identification of biomarkers of therapy response. Previous studies have suggested that patient-derived xenografts (PDXes) could be used in biomarker of response discovery. However, the clinical utility of PDXes in guiding real-time treatment decisions have only been reported in anecdotal forms. In the present study we aimed to develop a platform of melanoma patient-derived xenografts (PDXes), to assess whether treatment responses in mice would be applicable as a pre-selection tool for clinical trials. To that end, tumor biopsies from patients with stage III and IV metastatic malignant melanoma were transplanted into immunocompromised mice. Most melanoma biopsies generated serially transplantable PDX models, and their histology, and mutation status resembled their corresponding patient biopsy. RNAseq demonstrated that the expression profiles of the tumors are maintained throughout several passages in mice. The potential treatment for one patient was revealed by an in vitro drug screen and treating PDXes with the MEK inhibitor trametinib. In another patient, the BRAF mutation predicted the response of both the patient and its corresponding PDXes to MAP kinase pathway-targeted therapy. Importantly, in this unselected group of patients, the time from biopsy for generation of PDXes until death was significantly longer than the time required to reach the treatment phase of the PDXes. Thus, we demonstrate that it would be clinically meaningful to use this type of platform for a large proportion of melanoma patients as a pre-selection tool in clinical trials.

Citation Format: Berglind O. Einarsdottir, Roger Olofsson Bagge, Joydeep Bhadury, Henrik Jespersen, Lisa M. Nilsson, Jan Mattsson, Katarina Truvé, Peter Naredi, Ola Nilsson, Marcela Davila Lopez, Ulrika Stierner, Lars Ny, Jonas A. Nilsson. Melanoma patient-derived xenografts accurately models the disease and develop fast enough to guide treatment decisions. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr B38.

Melanoma patient-derived xenografts accurately model the disease and develop fast enough to guide treatment decisions

The development of novel therapies against melanoma would benefit from individualized tumor models to ensure the rapid and accurate identification of biomarkers of therapy response. Previous studies have suggested that patient-derived xenografts (PDXes) could be useful. However, the utility of PDXes in guiding real-time treatment decisions has only been reported in anecdotal forms. Here tumor biopsies from patients with stage III and IV metastatic malignant melanoma were transplanted into immunocompromised mice to generate PDXes. 23/26 melanoma biopsies generated serially transplantable PDX models, and their histology, mutation status and expression profile resembled their corresponding patient biopsy. The potential treatment for one patient was revealed by an in vitro drug screen and treating PDXes with the MEK inhibitor trametinib. In another patient, the BRAF mutation predicted the response of both the patient and its corresponding PDXes to MAPK-targeted therapy. Importantly, in this unselected group of patients, the time from biopsy for generation of PDXes until death was significantly longer than the time required to reach the treatment phase of the PDXes. Thus, it could be clinically meaningful to use this type of platform for melanoma patients as a pre-selection tool in clinical trials.

Abstract 503: Antioxidants markedly accelerate tumor growth and reduce survival in mice with KRAS- and BRAF-induced lung cancer by disrupting the ROS-p53 axis

Antioxidants are widely used to protect cells from damage induced by reactive oxygen species (ROS). The concept that antioxidants can help fight cancer is deeply rooted in the general population, promoted by the food supplement industry, and supported by some scientific studies. However, clinical trials have reported inconsistent results. Here, we show that supplementing the diet with the antioxidants N-acetylcysteine (NAC) or vitamin E markedly increases tumor progression and reduces survival by 50-60% in mouse models of B-RAF- and K-RAS-induced lung cancer. RNA sequencing revealed that NAC and vitamin E, which are structurally unrelated, produce highly coordinated changes in tumor transcriptome profiles, dominated by reduced expression of endogenous antioxidant genes. NAC and vitamin E increase tumor cell proliferation by reducing ROS, DNA damage, and p53 expression in mouse and human lung tumor cells. Inactivation of p53 increases tumor growth to a similar degree as antioxidants and abolishes the antioxidant effect. Thus, antioxidants accelerate tumor growth by disrupting the ROS-p53 axis. Because somatic mutations in p53 occur late in tumor progression, antioxidants may accelerate the growth of early tumors or precancerous lesions in high-risk populations such as smokers and patients with chronic obstructive pulmonary disease who receive NAC to relieve mucus production.

Citation Format: Volkan I. Sayin, Mohamed X. Ibrahim, Erik Larsson, Jonas A. Nilsson, Per Lindahl, Martin O. Bergö. Antioxidants markedly accelerate tumor growth and reduce survival in mice with KRAS- and BRAF-induced lung cancer by disrupting the ROS-p53 axis. [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 503. doi:10.1158/1538-7445.AM2014-503

Abstract 4565: Bet bromodomain inhibitors affects replication & cell cycle progression

Myc family of transcription factors contribute to pathogenesis in most cancers and their expression projects a poor prognosis. Genetic and pharmacological inhibition of Myc and several Myc targets leads to apoptosis and tumor regression. Recently, inhibitors of BET Bromodomain proteins (BETi) were shown to have anti-tumor properties and this has been attributed to Myc down-regulation. In this study, we show that two structurally distinct BETi affects replication and cell cycle progression at low concentrations where the transcriptome remains largely unaltered. At these concentrations, S-phase progression is hindered, as assessed by thymidine incorporation and flow cytometry analyses. However, in a cell-free system replication is not impaired suggesting that BETi-mediated block of replication is linked to effects on chromatin. Furthermore, at higher concentration of BET, S-phase entry of cells is completely abrogated. Ectopic expression of Myc fails to rescue these phenotypes, suggesting a novel function of BET bromodomain proteins in replication and cell cycle regulation.

Citation Format: Somsundar Veppil Muralidharan, Joydeep Bhadury, Lydia Green, Lisa M. Nilsson, Kevin G. Mclure, Jonas A. Nilsson. Bet bromodomain inhibitors affects replication & cell cycle progression. [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 4565. doi:10.1158/1538-7445.AM2014-4565

MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool

Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bind in the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal.

Chk2 deficiency in Myc overexpressing lymphoma cells elicits a synergistic lethal response in combination with PARP inhibition

Myc is a transcription factor frequently found deregulated in human cancer. The Myc-mediated cellular transformation process is associated with fast proliferative cells and inherent genomic instability, giving rise to malignant, invasive neoplasms with poor prognosis for survival. Transcription-independent functions of Myc include stimulation of replication. Excessive Myc expression stimulates a replication-associated DNA damage response that signals via the phosphoinositide-3-kinase (PI3K)-related protein kinases (PIKKs) ATM and ATR. These, in turn, activate the DNA damage transducers Chk1 and Chk2. Here, we show that Myc can stimulate Chek2 transcript indirectly in vitro as well as in B cells of λ-Myc transgenic mice or in the intestine of Apc (Min) mice. However, Chk2 is dispensable for Myc's ability to transform cells in vitro and for the survival of established lymphoma cells from λ-Myc transgenic mice. Chk2 deficiency induces polyploidy and slow growth, but the cells are viable and protected against DNA damage. Furthermore, inhibition of both Chk1/Chk2 with AZD7762 induces cell death and significantly delays disease progression of transplanted lymphoma cells in vivo. DNA damage recruits PARP family members to sites of DNA breaks that, in turn, facilitate the induction of DNA repair. Strikingly, combining Chk2 and PARP inhibition elicits a synergistic lethal response in the context of Myc overexpression. Our data indicates that only certain types of chemotherapy would give rise to a synergistic lethal response in combination with specific Chk2 inhibitors, which will be important if Chk2 inhibitors enter the clinic.

Therapeutic implications for the induced levels of Chk1 in Myc-expressing cancer cells

PURPOSE

The transcription factor c-Myc (or "Myc") is a master regulator of pathways driving cell growth and proliferation. MYC is deregulated in many human cancers, making its downstream target genes attractive candidates for drug development. We report the unexpected finding that B-cell lymphomas from mice and patients exhibit a striking correlation between high levels of Myc and checkpoint kinase 1 (Chk1).

EXPERIMENTAL DESIGN

By in vitro cell biology studies as well as preclinical studies using a genetically engineered mouse model, we evaluated the role of Chk1 in Myc-overexpressing cells.

RESULTS

We show that Myc indirectly induces Chek1 transcript and protein expression, independently of DNA damage response proteins such as ATM and p53. Importantly, we show that inhibition of Chk1, by either RNA interference or a novel highly selective small molecule inhibitor, results in caspase-dependent apoptosis that affects Myc-overexpressing cells in both in vitro and in vivo mouse models of B-cell lymphoma.

CONCLUSION

Our data suggest that Chk1 inhibitors should be further evaluated as potential drugs against Myc-driven malignancies such as certain B-cell lymphoma/leukemia, neuroblastoma, and some breast and lung cancers.

Myc suppression of Nfkb2 accelerates lymphomagenesis

Background

Deregulated c-Myc expression is a hallmark of several human cancers where it promotes proliferation and an aggressive tumour phenotype. Myc overexpression is associated with reduced activity of Rel/NF-κB, transcription factors that control the immune response, cell survival, and transformation, and that are frequently altered in cancer. The Rel/NF-κB family member NFKB2 is altered by chromosomal translocations or deletions in lymphoid malignancies and deletion of the C-terminal ankyrin domain of NF-κB2 augments lymphocyte proliferation.

Methods

Precancerous Eμ-Myc-transgenic B cells, Eμ-Myc lymphomas and human Burkitt lymphoma samples were assessed for Nfkb2 expression. The contribution of Nfkb2 to Myc-driven apoptosis, proliferation, and lymphomagenesis was tested genetically in vivo.

Results

Here we report that the Myc oncoprotein suppresses Nfkb2 expression in vitro in primary mouse fibroblasts and B cells, and in vivo in the Eμ-Myc transgenic mouse model of human Burkitt lymphoma (BL). NFKB2 suppression by Myc was also confirmed in primary human BL. Promoter-reporter assays indicate that Myc-mediated suppression of Nfkb2 occurs at the level of transcription. The contribution of Nfkb2 to Myc-driven lymphomagenesis was tested in vivo, where Nfkb2 loss was shown to accelerate lymphoma development in Eμ-Myc transgenic mice, by impairing Myc's apoptotic response.

Conclusions

Nfkb2 is suppressed by c-Myc and harnesses Myc-driven lymphomagenesis. These data thus link Myc-driven lymphomagenesis to the non-canonical NF-κB pathway.

Cut-off value for self-reported abnormal cold sensitivity and predictors for abnormality and severity in hand injuries

Our aim was to identify a cut-off value for self-reported, abnormal cold sensitivity and to identify cold sensitivity predictors after hand injuries. The Cold Intolerance Symptom Severity (CISS) questionnaire and a VAS question concerning discomfort on exposure to cold were investigated in 94 normal people and 88 patients. A CISS score >50 was defined as abnormal cold sensitivity. Multiple injured digits, an increased number of injured vessels, complete nerve injury and replantation were variables associated with high VAS scores. Factors linked to both abnormality and worse CISS or VAS scores were: the presence of bone injury; a larger number of repaired vessels; the use of vascular grafts and a high Hand Injury Severity Score (HISS). The causes of abnormality and severity suggest a multifactorial aetiology with bony, vascular and neural components. A cut-off for abnormality is useful for descriptive, comparative and assessment purposes.

Skp2 directs Myc-mediated suppression of p27Kip1 yet has modest effects on Myc-driven lymphomagenesis

The universal cyclin-dependent kinase inhibitor p27(Kip1) functions as a tumor suppressor, and reduced levels of p27(Kip1) connote poor prognosis in several human malignancies. p27(Kip1) levels are predominately regulated by ubiquitin-mediated turnover of the protein, which is marked for destruction by the E3 ubiquitin ligase SCF(Skp2) complex following its phosphorylation by the cyclin E-cyclin-dependent kinase 2 complex. Binding of phospho-p27(Kip1) is directed by the Skp2 F-box protein, and this is greatly augmented by its allosteric regulator Cks1. We have established that programmed expression of c-Myc in the B cells of Emu-Myc transgenic mice triggers p27(Kip1) destruction by inducing Cks1, that this response controls Myc-driven proliferation, and that loss of Cks1 markedly delays Myc-induced lymphomagenesis and cancels the dissemination of these tumors. Here, we report that elevated levels of Skp2 are a characteristic of Emu-Myc lymphomas and of human Burkitt lymphoma that bear MYC/Immunoglobulin chromosomal translocations. As expected, Myc-mediated suppression of p27(Kip1) was abolished in Skp2-null Emu-Myc B cells. However, the effect of Skp2 loss on Myc-driven proliferation and lymphomagenesis was surprisingly modest compared with the effects of Cks1 loss. Collectively, these findings suggest that Cks1 targets, in addition to p27(Kip1), are critical for Myc-driven proliferation and tumorigenesis.