ENDOLUNG trial. A phase 1/2 study of the Akt/mTOR inhibitor and autophagy inducer Ibrilatazar (ABTL0812) in combination with paclitaxel/carboplatin in patients with advanced/recurrent endometrial cancer.

BACKGROUND: Carboplatin and paclitaxel (CP) have been the standard of care for advanced/recurrent endometrial cancer (EC) for many years. However, this chemotherapy combination shows limited efficacy and recurrences often occur in less than 12 months. ABTL0812 is a novel drug that selectively kill cancer cells by cytotoxic autophagy and has shown anticancer efficacy in preclinical models of EC in combination with CP. METHODS: ENDOLUNG was an open-label, phase 1/2 clinical trial designed to determine the safety and efficacy of Ibrilatazar (ABTL0812) with CP in patients with advanced/recurrent EC and non-irradiable stage III and IV squamous non-small cell lung cancer (sq-NSCLC). The phase 1 part consisted of a 3 + 3 de-escalation design followed by an expansion cohort with 12 patients. The primary endpoint was safety. ABTL0812 starting dose was 1300 mg tid combined with carboplatin at area under the curve (AUC) 5 and paclitaxel at 175 mg/m2 both administered every 21 days for up to 8 cycles. The phase 2 part included a total of 51 patients. The primary endpoint was overall response rate (ORR) and the secondary endpoints included duration of response (DOR), progression-free survival (PFS) and overall survival (OS). RESULTS: During the phase 1 only one dose limiting toxicity (DLT), a grade 4 neutropenia, was observed in 1 out of 6 patients, thus no de-escalation was applied. One additional DLT, a grade 3 febrile neutropenia, was observed in the expansion cohort, thus the recommended phase 2 dose (RP2D) for ABTL0812 was established at 1300 mg tid. Most frequent hematological adverse events (AE) of the combination were neutropenia (52.9%), anemia (37.3%) and thrombocytopenia (19.6%). Nausea (66.7%), asthenia (66.7%), diarrhea (54.9%) and vomiting (54.9%) were the most frequent non-hematological adverse events (AEs). The combination of ABTL0812 plus CP showed an ORR of 65.8% (13.2% complete response and 52.6% partial response) with a median DOR of 7.4 months (95% CI: 6.3-10.8 months). Median PFS was 9.8 months (95% CI: 6.6-10.6) and median OS 23.6 months (95% CI 6.4-ND). Pharmacokinetic parameters were compatible with target engagement observed in preclinical studies, and blood pharmacodynamic biomarkers indicated sustained target regulation during, at least, 28 days after starting the treatment. CONCLUSIONS: This study suggests that the combination of ABTL0812 with CP is safe and feasible with an encouraging activity in patients with advanced/recurrent EC. Our data warrant further confirmation in prospective randomized trials. TRIAL REGISTRATION: EU Clinical Trial Register, EudraCT number 2016-001352-21 and National Clinical Trials Number, NCT03366480. Registration on 19 September 2016.

RANK is a poor prognosis marker and a therapeutic target in ER-negative postmenopausal breast cancer.

Despite strong preclinical data, the therapeutic benefit of the RANKL inhibitor, denosumab, in breast cancer patients, beyond the bone, is unclear. Aiming to select patients who may benefit from denosumab, we hereby analyzed RANK and RANKL protein expression in more than 2,000 breast tumors (777 estrogen receptor-negative, ER- ) from four independent cohorts. RANK protein expression was more frequent in ER- tumors, where it associated with poor outcome and poor response to chemotherapy. In ER- breast cancer patient-derived orthoxenografts (PDXs), RANKL inhibition reduced tumor cell proliferation and stemness, regulated tumor immunity and metabolism, and improved response to chemotherapy. Intriguingly, tumor RANK protein expression associated with poor prognosis in postmenopausal breast cancer patients, activation of NFKB signaling, and modulation of immune and metabolic pathways, suggesting that RANK signaling increases after menopause. Our results demonstrate that RANK protein expression is an independent biomarker of poor prognosis in postmenopausal and ER- breast cancer patients and support the therapeutic benefit of RANK pathway inhibitors, such as denosumab, in breast cancer patients with RANK+ ER- tumors after menopause.

Anticancer effects of ABTL0812, a clinical stage drug inducer of autophagy-mediated cancer cell death, in glioblastoma models.

Background: Glioblastoma multiforme (GBM) is the most malignant adult brain tumor. Current standard of care treatments have very limited efficacy, being the patients´ overall survival 14 months and the 2-year survival rate less than 10%. Therefore, the treatment of GBM is an urgent unmet clinical need. Methods: The aim of this study was to investigate in vitro and in vivo the potential of ABTL0812, an oral anticancer compound currently in phase II clinical stage, as a novel therapy for GBM. Results: We showed that ABTL0812 inhibits cell proliferation in a wide panel of GBM cell lines and patient-derived glioblastoma stem cells (GSCs) with half maximal inhibitory concentrations (IC50s) ranging from 15.2 µM to 46.9 µM. Additionally, ABTL0812 decreased GSCs neurosphere formation. GBM cells aggressiveness is associated with a trans-differentiation process towards a less differentiated phenotype known as proneural to mesenchymal transition (PMT). ABTL0812 was shown to revert PMT and induce cell differentiation to a less malignant phenotype in GBM cell lines and GSCs, and consequently reduced cell invasion. As previously shown in other cancer types, we demonstrated that the molecular mechanism of action of ABTL0812 in glioblastoma involves the inhibition of Akt/mTORC1 axis by overexpression of TRIB3, and the activation of endoplasmic reticulum (ER) stress/unfolded protein response (UPR). Both actions converge to induce autophagy-mediated cell death. ABTL0812 anticancer efficacy was studied in vivo using subcutaneous and orthotopic intra-brain xenograft tumor models. We demonstrated that ABTL0812 impairs tumor growth and increases disease-free survival and overall survival of mice. Furthermore, the histological analysis of tumors indicated that ABTL0812 decreases angiogenesis. Finally, we investigated the combination of ABTL0812 with the standard of care treatments for GBM radiotherapy and temozolomide in an orthotopic model, detecting that ABTL0812 potentiates the efficacy of both treatments and that the strongest effect is obtained with the triple combination of ABTL0812+radiotherapy+temozolomide. Conclusions: Overall, the present study demonstrated the anticancer efficacy of ABTL0812 as single agent and in combination with the GBM standard of care treatments in models of glioblastoma and supports the clinical investigation of ABTL0812 as a potential novel therapy for this aggressive brain tumor type.

The ERK5/NF-κB signaling pathway targets endometrial cancer proliferation and survival.

Endometrial cancer (EC) is the most common type of gynecologic cancer in women of developed countries. Despite surgery combined with chemo-/radiotherapy regimens, overall survival of patients with high-risk EC tumors is poor, indicating a need for novel therapies. The MEK5-ERK5 pathway is activated in response to growth factors and to different stressors, including oxidative stress and cytokines. Previous evidence supports a role for the MEK5-ERK5 pathway in the pathology of several cancers. We investigated the role of ERK5 in EC. In silico analysis of the PanCancer Atlas dataset showed alterations in components of the MEK5-ERK5 pathway in 48% of EC patients. Here, we show that ERK5 inhibition or silencing decreased EGF-induced EC cell proliferation, and that genetic deletion of MEK5 resulted in EC impaired proliferation and reduced tumor growth capacity in nude mice. Pharmacologic inhibition or ERK5 silencing impaired NF-kB pathway in EC cells and xenografts. Furthermore, we found a positive correlation between ERK5 and p65/RELA protein levels in human EC tumor samples. Mechanistically, genetic or pharmacologic impairment of ERK5 resulted in downregulation of NEMO/IKKγ expression, leading to impaired p65/RELA activity and to apoptosis in EC cells and xenografts, which was rescued by NEMO/IKKγ overexpression. Notably, ERK5 inhibition, MEK5 deletion or NF-kB inhibition sensitized EC cells to standard EC chemotherapy (paclitaxel/carboplatin) toxicity, whereas ERK5 inhibition synergized with paclitaxel to reduce tumor xenograft growth in mice. Together, our results suggest that the ERK5-NEMO-NF-κB pathway mediates EC cell proliferation and survival. We propose the ERK5/NF-κB axis as new target for EC treatment.

The anti-cancer drug ABTL0812 induces ER stress-mediated cytotoxic autophagy by increasing dihydroceramide levels in cancer cells.

ABTL0812 is a first-in-class small molecule with anti-cancer activity, which is currently in clinical evaluation in a phase 2 trial in patients with advanced endometrial and squamous non-small cell lung carcinoma (NCT03366480). Previously, we showed that ABTL0812 induces TRIB3 pseudokinase expression, resulting in the inhibition of the AKT-MTORC1 axis and macroautophagy/autophagy-mediated cancer cell death. However, the precise molecular determinants involved in the cytotoxic autophagy caused by ABTL0812 remained unclear. Using a wide range of biochemical and lipidomic analyses, we demonstrated that ABTL0812 increases cellular long-chain dihydroceramides by impairing DEGS1 (delta 4-desaturase, sphingolipid 1) activity, which resulted in sustained ER stress and activated unfolded protein response (UPR) via ATF4-DDIT3-TRIB3 that ultimately promotes cytotoxic autophagy in cancer cells. Accordingly, pharmacological manipulation to increase cellular dihydroceramides or incubation with exogenous dihydroceramides resulted in ER stress, UPR and autophagy-mediated cancer cell death. Importantly, we have optimized a method to quantify mRNAs in blood samples from patients enrolled in the ongoing clinical trial, who showed significant increased DDIT3 and TRIB3 mRNAs. This is the first time that UPR markers are reported to change in human blood in response to any drug treatment, supporting their use as pharmacodynamic biomarkers for compounds that activate ER stress in humans. Finally, we found that MTORC1 inhibition and dihydroceramide accumulation synergized to induce autophagy and cytotoxicity, phenocopying the effect of ABTL0812. Given the fact that ABTL0812 is under clinical development, our findings support the hypothesis that manipulation of dihydroceramide levels might represents a new therapeutic strategy to target cancer.Abbreviations: 4-PBA: 4-phenylbutyrate; AKT: AKT serine/threonine kinase; ATG: autophagy related; ATF4: activating transcription factor 4; Cer: ceramide; DDIT3: DNA damage inducible transcript 3; DEGS1: delta 4-desaturase, sphingolipid 1; dhCer: dihydroceramide; EIF2A: eukaryotic translation initiation factor 2 alpha; EIF2AK3: eukaryotic translation initiation factor 2 alpha kinase 3; ER: endoplasmic reticulum; HSPA5: heat shock protein family A (Hsp70) member 5; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; MTORC1: mechanistic target of rapamycin kinase complex 1; NSCLC: non-small cell lung cancer; THC: Δ9-tetrahydrocannabinol; TRIB3: tribbles pseudokinase 3; XBP1: X-box binding protein 1; UPR: unfolded protein response.

The antitumour drug ABTL0812 impairs neuroblastoma growth through endoplasmic reticulum stress-mediated autophagy and apoptosis.

Neuroblastoma is the leading cause of cancer death in children aged 1 to 4 years. Particularly, five-year overall survival for high-risk neuroblastoma is below 50% with no curative options when refractory or relapsed. Most of current therapies target cell division and proliferation, thereby inducing DNA damage and programmed cell death. However, aggressive tumours often present alterations of these processes and are resistant to therapy. Therefore, exploring alternative pathways to induce tumour cell death will provide new therapeutic opportunities for these patients. In this study we aimed at testing the therapeutic potential of ABTL0812, a novel anticancer drug that induces cytotoxic autophagy to eliminate cancer cells, which is currently in phase II clinical trials of adult tumours. Here, we show that ABTL0812 impaired the viability of clinical representative neuroblastoma cell lines regardless of genetic alterations associated to bad prognosis and resistance to therapy. Oral administration of ABTL0812 to mice bearing neuroblastoma xenografts impaired tumour growth. Furthermore, our findings revealed that, in neuroblastoma, ABTL0812 induced cancer cell death via induction of endoplasmic reticulum stress, activation of the unfolded protein response, autophagy and apoptosis. Remarkably, ABTL0812 potentiated the antitumour activity of chemotherapies and differentiating agents such as irinotecan and 13-cis-retinoic acid. In conclusion, ABTL0812 distinctive mechanism of action makes it standout to be used alone or in combination in high-risk neuroblastoma patients.

Therapeutic Potential of Autophagy Modulation in Cholangiocarcinoma.

Autophagy is a multistep catabolic process through which misfolded, aggregated or mutated proteins and damaged organelles are internalized in membrane vesicles called autophagosomes and ultimately fused to lysosomes for degradation of sequestered components. The multistep nature of the process offers multiple regulation points prone to be deregulated and cause different human diseases but also offers multiple targetable points for designing therapeutic strategies. Cancer cells have evolved to use autophagy as an adaptive mechanism to survive under extremely stressful conditions within the tumor microenvironment, but also to increase invasiveness and resistance to anticancer drugs such as chemotherapy. This review collects clinical evidence of autophagy deregulation during cholangiocarcinogenesis together with preclinical reports evaluating compounds that modulate autophagy to induce cholangiocarcinoma (CCA) cell death. Altogether, experimental data suggest an impairment of autophagy during initial steps of CCA development and increased expression of autophagy markers on established tumors and in invasive phenotypes. Preclinical efficacy of autophagy modulators promoting CCA cell death, reducing invasiveness capacity and resensitizing CCA cells to chemotherapy open novel therapeutic avenues to design more specific and efficient strategies to treat this aggressive cancer.

The novel proautophagy anticancer drug ABTL0812 potentiates chemotherapy in adenocarcinoma and squamous nonsmall cell lung cancer.

Around 40% of newly diagnosed lung cancer patients are Stage IV, where the improvement of survival and reduction of disease-related adverse events is the main goal for oncologists. In this scenario, we present preclinical evidence supporting the use of ABTL0812 in combination with chemotherapy for treating advanced and metastatic Nonsmall cell lung adenocarcinomas (NSCLC) and squamous carcinomas. ABTL0812 is a new chemical entity, currently in Phase 1b/2a clinical trial for advanced squamous NSCLC in combination with paclitaxel and carboplatin (P/C), after successfully completing the first-in-human trial where it showed an excellent safety profile and signs of efficacy. We show here that ABTL0812 inhibits Akt/mTOR axis by inducing the overexpression of TRIB3 and activating autophagy in lung squamous carcinoma cell lines. Furthermore, treatment with ABTL0812 also induces AMPK activation and ROS accumulation. Moreover, combination of ABTL0812 with chemotherapy markedly increases the therapeutic effect of chemotherapy without increasing toxicity. We further show that combination of ABTL0812 and chemotherapy induces nonapoptotic cell death mediated by TRIB3 activation and autophagy induction. We also present preliminary clinical data indicating that TRIB3 could serve as a potential novel pharmacodynamic biomarker to monitor ABTL0812 activity administered alone or in combination with chemotherapy in squamous NSCLC patients. The safety profile of ABTL0812 and its good synergy with chemotherapy potentiate the therapeutic potential of current lines of treatment based on chemotherapy regimens, arising as a promising option for improving these patients therapeutic expectancy.

Therapeutic potential of the new TRIB3-mediated cell autophagy anticancer drug ABTL0812 in endometrial cancer.

OBJECTIVES: The PI3K/AKT/mTOR pathway is frequently overactivated in endometrial cancer (EC). We assessed the efficacy of ABTL0812, a novel first-in-class molecule presenting a unique mechanism of action inhibiting this pathway. METHODS: We investigated the effects of ABTL0812 on proliferation, cell death and modulation of intracellular signaling pathways in a wide panel of endometrioid and non-endometrioid cell lines, an inducible PTEN knock-out murine model, and two patient-derived xenograft murine models of EC. Then, TRIB3 expression was evaluated as potential ABTL0812 pharmacodynamic biomarker in a Phase 1b/2a clinical trial. RESULTS: ABTL0812 induced an upregulation of TRIB3 expression, resulting in the PI3K/AKT/mTOR axis inhibition and autophagy cell death induction on EC cells but not in healthy endometrial cells. ABTL0812 treatment also impaired PTEN knock-out cells to progress from hyperplasia to cancer. The therapeutic effects of ABTL0812 were demonstrated in vivo. ABTL0812 increased TRIB3 mRNA levels in whole blood samples of eight EC patients, demonstrating that TRIB3 mRNA could be used as a pharmacodynamic biomarker to monitor the ABTL0812 treatment. CONCLUSIONS: ABTL0812 may represent a novel and highly effective therapeutic agent by inducing TRIB3 expression and autophagy in EC patients, including those with poorer prognosis.

Targeting p38α Increases DNA Damage, Chromosome Instability, and the Anti-tumoral Response to Taxanes in Breast Cancer Cells.

Breast cancer is the second leading cause of cancer-related death among women. Here we report a role for the protein kinase p38α in coordinating the DNA damage response and limiting chromosome instability during breast tumor progression, and identify the DNA repair regulator CtIP as a p38α substrate. Accordingly, decreased p38α signaling results in impaired ATR activation and homologous recombination repair, with concomitant increases in replication stress, DNA damage, and chromosome instability, leading to cancer cell death and tumor regression. Moreover, we show that pharmacological inhibition of p38α potentiates the effects of taxanes by boosting chromosome instability in murine models and patient-derived xenografts, suggesting the potential interest of combining p38α inhibitors with chemotherapeutic drugs that induce chromosome instability.

Resistance to Taxanes in Triple-Negative Breast Cancer Associates with the Dynamics of a CD49f+ Tumor-Initiating Population.

Taxanes are a mainstay of treatment for breast cancer, but resistance often develops followed by metastatic disease and mortality. Aiming to reveal the mechanisms underlying taxane resistance, we used breast cancer patient-derived orthoxenografts (PDX). Mimicking clinical behavior, triple-negative breast tumors (TNBCs) from PDX models were more sensitive to docetaxel than luminal tumors, but they progressively acquired resistance upon continuous drug administration. Mechanistically, we found that a CD49f+ chemoresistant population with tumor-initiating ability is present in sensitive tumors and expands during the acquisition of drug resistance. In the absence of the drug, the resistant CD49f+ population shrinks and taxane sensitivity is restored. We describe a transcriptional signature of resistance, predictive of recurrent disease after chemotherapy in TNBC. Together, these findings identify a CD49f+ population enriched in tumor-initiating ability and chemoresistance properties and evidence a drug holiday effect on the acquired resistance to docetaxel in triple-negative breast cancer.

Neonatal Fc receptor blockade by Fc engineering ameliorates arthritis in a murine model.

Multiple autoimmune diseases are characterized by the involvement of autoreactive Abs in pathogenesis. Problems associated with existing therapeutics such as the delivery of intravenous immunoglobulin have led to interest in developing alternative approaches using recombinant or synthetic methods. Toward this aim, in the current study, we demonstrate that the use of Fc-engineered Abs (Abs that enhance IgG degradation [Abdegs]) to block neonatal FcR (FcRn) through high-affinity, Fc region binding is an effective strategy for the treatment of Ab-mediated disease. Specifically, Abdegs can be used at low, single doses to treat disease in the K/B×N serum transfer model of arthritis using BALB/c mice as recipients. Similar therapeutic effects are induced by 25- to 50-fold higher doses of i.v. Ig. Importantly, we show that FcRn blockade is a primary contributing factor toward the observed reduction in disease severity. The levels of albumin, which is also recycled by FcRn, are not affected by Abdeg delivery. Consequently, Abdegs do not alter FcRn expression levels or subcellular trafficking behavior. The engineering of Ab Fc regions to generate potent FcRn blockers therefore holds promise for the therapy of Ab-mediated autoimmunity.