MCL1 inhibition is effective against a subset of small-cell lung cancer with high MCL1 and low BCL-XL expression

Comprehensive genomic and spatial immune infiltration analysis of survival outliers in extensive-stage small cell lung cancer receiving first-line chemoimmunotherapy

BACKGROUND

A minority of patients with extensive-stage small cell lung cancer (ES-SCLC) exhibit prolonged survival following first-line chemoimmunotherapy, which warrants the use of reliable biomarkers. Here, we investigated the disparities in genomics and immune cell spatial distribution between long- and short-term survival of patients with ES-SCLC.

METHODS

We retrospectively recruited 11 long-term (>2 years) and 13 short-term (<9 months) ES-SCLC survivors receiving first-line chemoimmunotherapy. The samples were processed using targeted next-generation sequencing (tNGS), programmed death ligand-1 staining, multiplex immunohistochemical staining for immune cells (mIHC), tumor mutation burden (TMB), and chromosomal instability score measurements. The expression of putative genes in SCLC at the bulk and single-cell RNA-sequencing levels, as well as the role of putative genes in pan-cancer immunotherapy cohorts, were analyzed.

RESULTS

At the genomic level, a greater proportion of the smoking signature and higher TMB (>3.1) were associated with favorable survival. At the single-gene and pathway levels, tNGS revealed that MCL1 and STMN1 amplification and alterations in the apoptosis pathway were more common in short-term survivors, whereas alterations in the DLL3, KMT2B, HGF, EPHA3, ADGRB3, lysine deprivation, and HGF-cMET pathways were observed more frequently in long-term survivors. mIHC analysis of immune cells with different spatial distributions revealed that long-term survivors presented increased numbers of M1-like macrophages in all locations and decreased numbers of CD8+ T cells in the tumor stroma. Bulk transcriptomic analysis demonstrated that high levels of STMN1 and DLL3 represented an immune-suppressive tumor immune microenvironment (TIME), whereas HGF indicated an immune-responsive TIME. The expression levels of our putative genes were comparative in both TP53/RB1 mutant-type and TP53/RB1 wild-type. At the single-cell level, STMN1, MCL1, and DLL3 were highly expressed among all molecular subtypes (SCLC-A, SCLC-N, and SCLC-P), with STMN1 being enriched in cell division and G2M checkpoint pathways.

CONCLUSIONS

For ES-SCLC patients receiving first-line chemoimmunotherapy, alterations in DLL3, KMT2B, HGF, EPHA3, and ADGRB3 and a greater proportion of M1-like macrophages infiltration in all locations were predictors of favorable survival, while MCL1 and STMN1 amplification, as well as a greater proportion of CD8+ T cells infiltrating the tumor stroma, predicted worse survival.

The Clinicopathological and Molecular Characteristics of Endocervical Gastric-Type Adenocarcinoma and the Use of Claudin18.2 as a Potential Therapeutic Target

Endocervical gastric-type adenocarcinoma (GAS) is an aggressive type of endocervical mucinous adenocarcinoma characterized as being unrelated to human papillomavirus (HPV) and resistant to chemo/radiotherapy. In this study, we investigated the histology, immunohistochemistry patterns, and molecular characteristics in a large cohort of GAS (n = 62). Histologically, the majority of GAS cases exhibited a distinct morphology resembling gastric glands, although 2 exceptional cases exhibited HPV-associated adenocarcinoma morphology while retaining the characteristic histology of GAS at the invasive front. By immunohistochemistry, Claudin18.2 emerged as a highly sensitive and specific marker for GAS. Additionally, the strong expression of Claudin18.2 in patients with GAS indicated the potential of anti-Claudin18.2 therapy in the treatment of GAS. Other immunohistochemistry markers, including Muc6, p16, p53, Pax8, ER, and PR, may provide additional diagnostic clues for GAS. Quantitative methylation analysis revealed that the overexpression of Claudin18.2 in GAS was governed by the hypomethylation of the CLDN18.2 promoter CpG islands. To further elucidate the pathogenic mechanisms of GAS and its relationship with gastric adenocarcinoma, we performed whole exome sequencing on 11 GAS and 9 gastric adenocarcinomas. TP53, CDKN2A, STK11, and TTN emerged as the most frequently mutated genes in GAS. Mutations in these genes primarily affected cell growth, cell cycle regulation, senescence, and apoptosis. Intriguingly, these top mutated genes in GAS were also commonly mutated in gastric and pancreaticobiliary adenocarcinomas. Regarding germline variants, we identified a probably pathogenic variant in SPINK1, a gene linked to hereditary pancreatic cancer syndrome, in one GAS sample. This finding suggests a potential pathogenic link between pancreatic cancers and GAS. Overall, GAS exhibits molecular characteristics that resemble those observed in gastric and pancreaticobiliary adenocarcinomas, thereby lending support to the aggressive nature of GAS compared with HPV-associated adenocarcinoma.

Circulating tumor cells: advancing personalized therapy in small cell lung cancer patients

Small cell lung cancer (SCLC) is a highly aggressive cancer with a dismal 5-year survival of < 7%, despite the addition of immunotherapy to first-line chemotherapy. Specific tumor biomarkers, such as delta-like ligand 3 (DLL3) and schlafen11 (SLFN11), may enable the selection of more efficacious, novel immunomodulating targeted treatments like bispecific T-cell engaging monoclonal antibodies (tarlatamab) and chemotherapy with PARP inhibitors. However, obtaining a tissue biopsy sample can be challenging in SCLC. Circulating tumor cells (CTCs) have the potential to provide molecular insights into a patient's cancer through a "simple" blood test. CTCs have been studied for their prognostic ability in SCLC; however, their value in guiding treatment decisions is yet to be elucidated. This review explores novel and promising targeted therapies in SCLC, summarizes current knowledge of CTCs in SCLC, and discusses how CTCs can be utilized for precision medicine.

Apoptosis Pathway-Associated Proteins Are Frequently Expressed in Melanoma: A Study of 32 Cases With Focus on Acral Lentiginous Melanoma

ABSTRACT

Acral lentiginous melanoma (ALM) is an aggressive type of cutaneous melanoma (CM) that arises on palms, soles, and nail units. ALM is rare in White population, but it is relatively more frequent in dark-skinned populations. There is an unmet need to develop new personalized and more effective treatments strategies for ALM. Increased expression of antiapoptotic proteins (ie, BCL2, MCL1) has been shown to contribute to tumorigenesis and therapeutic resistance in multiple tumor types and has been observed in a subset of ALM and mucosal melanoma cell lines in vivo and in vitro. However, little is known about their expression and clinical significance in patients with ALM. Thus, we assessed protein expression of BCL2, MCL1, BIM, and BRAF V600E by immunohistochemistry in 32 melanoma samples from White and Hispanic populations, including ALM and non-ALM (NALM). BCL2, MCL1, and BIM were expressed in both ALM and NALM tumors, and no significant differences in expression of any of these proteins were detected between the groups, in our relatively small cohort. There were no significant associations between protein expression and BRAF V600E status, overall survival, or ethnicity. In summary, ALM and NALM demonstrate frequent expressions of apoptosis-related proteins BCL2, MCL1, and BIM. Our findings suggest that patients with melanoma, including ALM, may be potential candidates for apoptosis-directed therapies.

Combination Therapy with EGFR Tyrosine Kinase Inhibitors and TEAD Inhibitor Increases Tumor Suppression Effects in EGFR Mutation-positive Lung Cancer

EGFR-tyrosine kinase inhibitors (TKI) are the first-line therapies for EGFR mutation-positive lung cancer. EGFR-TKIs have favorable therapeutic effects. However, a large proportion of patients with EGFR mutation-positive lung cancer subsequently relapse. Some cancer cells survive the initial treatment with EGFR-TKIs, and this initial survival may be associated with subsequent recurrence. Therefore, we aimed to overcome the initial survival against EGFR-TKIs. We hypothesized that yes-associated protein 1 (YAP1) is involved in the initial survival against EGFR-TKIs, and we confirmed the combined effect of EGFR-TKIs and a YAP1-TEAD pathway inhibitor. The KTOR27 (EGFR kinase domain duplication) lung cancer cell lines established from a patient with EGFR mutation-positive lung cancer and commercially available PC-9 and HCC827 (EGFR exon 19 deletions) lung cancer cell lines were used. These cells were used to evaluate the in vitro and in vivo effects of VT104, a TEAD inhibitor. In addition, YAP1 involvement was investigated in pathologic specimens. YAP1 was activated by short-term EGFR-TKI treatment in EGFR mutation-positive lung cancer cells. In addition, inhibiting YAP1 function using siRNA increased the sensitivity to EGFR-TKIs. Combination therapy with VT104 and EGFR-TKIs showed better tumor-suppressive effects than EGFR-TKIs alone, in vitro and in vivo. Moreover, the combined effect of VT104 and EGFR-TKIs was observed regardless of the localization status of YAP1 before EGFR-TKI exposure. These results suggest that combination therapy with the TEAD inhibitor and EGFR-TKIs may improve the prognosis of patients with EGFR mutation-positive lung cancer.

PROTAC-Mediated Dual Degradation of BCL-xL and BCL-2 Is a Highly Effective Therapeutic Strategy in Small-Cell Lung Cancer

BCL-xL and BCL-2 are validated therapeutic targets in small-cell lung cancer (SCLC). Targeting these proteins with navitoclax (formerly ABT263, a dual BCL-xL/2 inhibitor) induces dose-limiting thrombocytopenia through on-target BCL-xL inhibition in platelets. Therefore, platelet toxicity poses a barrier in advancing the clinical translation of navitoclax. We have developed a strategy to selectively target BCL-xL in tumors, while sparing platelets, by utilizing proteolysis-targeting chimeras (PROTACs) that hijack the cellular ubiquitin proteasome system for target ubiquitination and subsequent degradation. In our previous study, the first-in-class BCL-xL PROTAC, called DT2216, was shown to have synergistic antitumor activities when combined with venetoclax (formerly ABT199, BCL-2-selective inhibitor) in a BCL-xL/2 co-dependent SCLC cell line, NCI-H146 (hereafter referred to as H146), in vitro and in a xenograft model. Guided by these findings, we evaluated our newly developed BCL-xL/2 dual degrader, called 753b, in three BCL-xL/2 co-dependent SCLC cell lines and the H146 xenograft models. 753b was found to degrade both BCL-xL and BCL-2 in these cell lines. Importantly, it was considerably more potent than DT2216, navitoclax, or DT2216 + venetoclax in reducing the viability of BCL-xL/2 co-dependent SCLC cell lines in cell culture. In vivo, 5 mg/kg weekly dosing of 753b was found to lead to significant tumor growth delay, similar to the DT2216 + venetoclax combination in H146 xenografts, by degrading both BCL-xL and BCL-2. Additionally, 753b administration at 5 mg/kg every four days induced tumor regressions. At this dosage, 753b was well tolerated in mice, without observable induction of severe thrombocytopenia as seen with navitoclax, and no evidence of significant changes in mouse body weights. These results suggest that the BCL-xL/2 dual degrader could be an effective and safe therapeutic for a subset of SCLC patients, warranting clinical trials in future.

PROTAC-mediated dual degradation of BCL-xL and BCL-2 is a highly effective therapeutic strategy in small-cell lung cancer

BCL-xL and BCL-2 are validated therapeutic targets in small-cell lung cancer (SCLC). Targeting these proteins with navitoclax (formerly ABT263, a dual BCL-xL/2 inhibitor) induces dose-limiting thrombocytopenia through on-target BCL-xL inhibition in platelets. Therefore, platelet toxicity poses a barrier in advancing the clinical translation of navitoclax. We have developed a strategy to selectively target BCL-xL in tumors, while sparing platelets, by utilizing proteolysis-targeting chimeras (PROTACs) that hijack the cellular ubiquitin proteasome system for target ubiquitination and subsequent degradation. In our previous study, the first-in-class BCL-xL PROTAC, called DT2216, was shown to have synergistic antitumor activities when combined with venetoclax (formerly ABT199, BCL-2-selective inhibitor) in a BCL-xL/2 co-dependent SCLC cell line, NCI-H146 (hereafter referred to as H146), in vitro and in a xenograft model. Guided by these findings, we evaluated our newly developed BCL-xL/2 dual degrader, called 753b, in three BCL-xL/2 co-dependent SCLC cell lines and the H146 xenograft models. 753b was found to degrade both BCL-xL and BCL-2 in these cell lines. Importantly, it was considerably more potent than DT2216, navitoclax, or DT2216+venetoclax to reduce the viability of BCL-xL/2 co-dependent SCLC cell lines in cell culture. In vivo, 5 mg/kg weekly dosing of 753b leads to significant tumor growth delay similar to the DT2216+venetoclax combination in H146 xenografts by degrading both BCL-xL and BCL-2. Additionally, 753b administration at 5 mg/kg every four days induced tumor regressions. 753b at this dosage was well tolerated in mice without induction of severe thrombocytopenia as seen with navitoclax nor induced significant changes in mouse body weights. These results suggest that the BCL-xL/2 dual degrader could be an effective and safe therapeutic for a subset of SCLC patients warranting clinical trials in future.

The Role of miR-29a and miR-143 on the Anti-apoptotic MCL-1/cIAP-2 Genes Expression in EGFR Mutated Non-small Cell Lung Carcinoma Patients

The survival rate of lung cancer is low due to the high frequency of drug resistance in patients with mutations in the driver genes. Overexpression of anti-apoptotic genes is one of the most prominent features of tumor drug resistance. EGFR signaling induces the expression of anti-apoptotic genes. Also, microRNAs (miRNAs) have a critical role in regulating biological functions such as apoptosis; a process mostly eluded in cancer progression. The mutation screening was performed on one thousand non-small cell lung carcinoma patients to enroll clinical samples in this study. Bioinformatics analysis predicted that miRNAs (miR-29a, miR-143) might regulate MCL-1 and cIAP-2 expression. We investigated the expression of MCL-1, cIAP-2, miR-29a, and miR-143 encoding genes in adenocarcinoma patients with or without EGFR mutations before treatment. The potential role of miR-29a and miR-143 on gene expression was evaluated by overexpression and luciferase assays in HEK-293T cells. EGFR mutations were found in 262 patients (26.2%) with a greater incidence in females (36.23% vs. 20.37%, P = 0.001). The expression levels of MCL-1 and cIAP-2 genes in patients with mutated EGFR were higher than those of wild-type EGFR. In contrast, compared to those of patients with wild-type EGFR, the expression levels of miR-29a and miR-143 were lower in the patients carrying EGFR mutations. In cell culture, overexpression of miR-29a and miR-143 significantly downregulated the expression of MCL-1 and cIAP-2. Dual-luciferase reporter experiments confirmed that miR-29a and miR-143 target MCL-1 and cIAP-2 mRNAs, respectively. Our results suggest that upregulation of EGFR signaling in lung cancer cells may increase anti-apoptotic MCL-1 and cIAP-2 gene expression, possibly through downregulation of miR-29a-3p and miR-143-3p.

Clinicopathological molecular characterizations of sinonasal NUT carcinoma: a report of two cases and a literature review

Background

Nuclear protein in testis (NUT) carcinoma (NC) is a rare, aggressive tumor with a typical NUTM1 gene rearrangement.

Methods

Herein, we report a series of 2 cases of sinonasal NC: one in a 16-year-old woman and one in a 37-year-old man. Immunohistochemistry (IHC) staining for NUT (C52B1), fluorescence in situ hybridization (FISH), and next generation sequencing (NGS) sequencing were performed to investigate the morphological and genetic features of sinonasal NC.

Results

The two cases presented similar pathological features and IHC markers, and typical morphological changes, including undifferentiated cells and abrupt keratinization, were observed, with numerous mitotic figures and widespread tumor necrosis. Diffuse expression of NUT, CK, p63, and p40 was noted, while the tumors were negative for synaptophysin, chromogranin A, S-100, EBV-ISH, and PD-L1. Both tumors harbored a NUTM1 rearrangement. Subsequent sequencing revealed a rare BRD3::NUTM1 fusion and a classic BRD4::NUTM1 fusion. In addition, MCL1 copy number gain (2.1), low tumor mutation burden and stable microsatellites, were also confirmed. Case 1 received surgery and chemoradiotherapy but died 13 months after local recurrence and subsequent lung and bone metastasis. Case 2 underwent chemoradiotherapy and unfortunately died from the disease 6 months later. A review of all previously reported cases of sinonasal NCs (n=55) revealed that these tumors occur more frequently in female pediatric patients (n=11, male: female =3:8), whereas this sex difference is not observed in adult patients (n=44, male: female =23:21). The median survival times of pediatric and adult patients were 17 and 13.8 months, respectively.

Conclusion

Sinonasal NC presents typical undifferentiated or poorly differentiated cells, abrupt keratinization features and heterogeneous genotypes, including BRD4::NUTM1 and BRD3::NUTM1 fusions, with low tumor mutation burden and stable microsatellites.

LNS8801 inhibits Acute Myeloid Leukemia by Inducing the Production of Reactive Oxygen Species and Activating the Endoplasmic Reticulum Stress Pathway

Despite recent therapeutic advances, the 5-year survival rate for adults with acute myeloid leukemia (AML) is poor and standard-of-care chemotherapy is associated with significant toxicity, highlighting the need for new therapeutic approaches. Recent work from our group and others established that the G protein-coupled estrogen receptor (GPER) is tumor suppressive in melanoma and other solid tumors. We performed a preliminary screen of human cancer cell lines from multiple malignancies and found that LNS8801, a synthetic pharmacologic agonist of GPER currently in early phase clinical trials, promoted apoptosis in human AML cells. Using human AML cell lines and primary cells, we show that LNS8801 inhibits human AML in preclinical in vitro models, while not affecting normal mononuclear cells. Although GPER is broadly expressed in normal and malignant myeloid cells, this cancer-specific LNS8801-induced inhibition appeared to be independent of GPER signaling. LNS8801 induced AML cell death primarily through a caspase-dependent apoptosis pathway. This was independent of secreted classical death receptor ligands, and instead required induction of reactive oxygen species (ROS) and activation of endoplasmic reticulum (ER) stress response pathways including IRE1α. These studies demonstrate a novel activity of LNS8801 in AML cells and show that targeting ER stress with LNS8801 may be a useful therapeutic approach for AML.

Significance

Previous work demonstrated that LNS8801 inhibits cancer via GPER activation, especially in solid tumors. Here we show that LNS8801 inhibits AML via GPER-independent mechanisms that include ROS induction and ER activation.

Dual targeting of BCL-2 and MCL-1 in the presence of BAX breaks venetoclax resistance in human small cell lung cancer

BACKGROUND

No targeted drugs are currently available against small cell lung cancer (SCLC). BCL-2 family members are involved in apoptosis regulation and represent therapeutic targets in many malignancies.

METHODS

Expression of BCL-2 family members in 27 SCLC cell lines representing all known four SCLC molecular subtypes was assessed by qPCR, Western blot and mass spectrometry-based proteomics. BCL-2 and MCL-1 inhibition (venetoclax and S63845, respectively) was assessed by MTT assay and flow cytometry and in mice bearing human SCLC tumours. Drug interactions were calculated using the Combenefit software. Ectopic BAX overexpression was achieved by expression plasmids.

RESULTS

The highest BCL-2 expression levels were detected in ASCL1- and POU2F3-driven SCLC cells. Although sensitivity to venetoclax was reflected by BCL-2 levels, not all cell lines responded consistently despite their high BCL-2 expression. MCL-1 overexpression and low BAX levels were both characteristic for venetoclax resistance in SCLC, whereas the expression of other BCL-2 family members did not affect therapeutic efficacy. Combination of venetoclax and S63845 resulted in significant, synergistic in vitro and in vivo anti-tumour activity and apoptosis induction in double-resistant cells; however, this was seen only in a subset with detectable BAX. In non-responding cells, ectopic BAX overexpression sensitised to venetoclax and S63845 and, furthermore, induced synergistic drug interaction.

CONCLUSIONS

The current study reveals the subtype specificity of BCL-2 expression and sheds light on the mechanism of venetoclax resistance in SCLC. Additionally, we provide preclinical evidence that combined BCL-2 and MCL-1 targeting is an effective approach to overcome venetoclax resistance in high BCL-2-expressing SCLCs with intact BAX.

BH3 mimetics and TKI combined therapy for Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) was considered for a long time one of the most hostile leukemia that was incurable for most of the patients, predominantly due to the extreme resistance to chemotherapy. Part of the resistance to cell death (apoptosis) is the result of increased levels of anti-apoptotic and decreased levels of pro-apoptotic member of the BCL-2 family induced by the BCR-ABL1 oncoprotein. BCR-ABL1 is a constitutively active tyrosine kinase responsible for initiating multiple and oncogenic signaling pathways. With the development of specific BCR-ABL1 tyrosine kinase inhibitors (TKIs) CML became a much more tractable disease. Nevertheless, TKIs do not cure CML patients and a substantial number of them develop intolerance or become resistant to the treatment. Therefore, novel anti-cancer strategies must be developed to treat CML patients independently or in combination with TKIs. Here, we will discuss the mechanisms of BCR-ABL1-dependent and -independent resistance to TKIs and the use of BH3-mimetics as a potential tool to fight CML.

BCL-2 protein family: attractive targets for cancer therapy

Acquired resistance to cell death is a hallmark of cancer. The BCL-2 protein family members play important roles in controlling apoptotic cell death. Abnormal over-expression of pro-survival BCL-2 family members or abnormal reduction of pro-apoptotic BCL-2 family proteins, both resulting in the inhibition of apoptosis, are frequently detected in diverse malignancies. The critical role of the pro-survival and pro-apoptotic BCL-2 family proteins in the regulation of apoptosis makes them attractive targets for the development of agents for the treatment of cancer. This review describes the roles of the various pro-survival and pro-apoptotic members of the BCL-2 protein family in normal development and organismal function and how defects in the control of apoptosis promote the development and therapy resistance of cancer. Finally, we discuss the development of inhibitors of pro-survival BCL-2 proteins, termed BH3-mimetic drugs, as novel agents for cancer therapy.

Accurate treatment of small cell lung cancer: Current progress, new challenges and expectations

Small cell lung cancer (SCLC) is a deadly disease with poor prognosis. Fast growing speed, inclination to metastasis, enrichment in cancer stem cells altogether constitute its aggressive nature. In stark contrast to non-small cell lung cancer (NSCLC) that strides vigorously on the road to precision oncology, SCLC has been on the embryonic path to achieve effective personalized treatments. The survival of patients with SCLC have not been improved greatly, which could be possibly due to our inadequate understanding of genetic alterations of SCLC. Recently, encouraging effects have been observed in patients with SCLC undergoing immunotherapy. However, exciting results have only been observed in a small fraction of patients with SCLC, warranting biomarkers predictive of responses as well as novel therapeutic strategies. In addition, SCLC has previously been viewed to be homogeneous. However, perspectives have been changed thanks to the advances in sequencing techniques and platforms, which unfolds the complex heterogeneity of SCLC both genetically and non-genetically, rendering the treatment of SCLC a further step forward into the precision era. To outline the road of SCLC towards precision oncology, we summarize the progresses and achievements made in precision treatment in SCLC in genomic, transcriptomic, epigenetic, proteomic and metabolic dimensions. Moreover, we conclude relevant therapeutic vulnerabilities in SCLC. Clinically tested drugs and clinical trials have also been demonstrated. Ultimately, we look into the opportunities and challenges ahead to advance the individualized treatment in pursuit of improved survival for patients with SCLC.

Evaluation of HIF-1α Expression in a Rat Glioma Model Using Intravoxel Incoherent Motion and R2* Mapping

Accurate evaluation of HIF-1α levels can facilitate the detection of hypoxia niches in glioma and treatment decisions. To investigate the feasibility of intravoxel incoherent motion (IVIM) and R2* Mapping for detecting HIF-1α expression levels, sixteen rats with intracranial C6 gliomas were subjected to IVIM and R2* Mapping using a 7 Tesla MRI scanner. For each model, the brain tissue on the HIF-1α-stained slices was subdivided into multiple square regions of interest (ROIs) with areas of 1 mm², for which HIF-1α expression was assessed by HALO software to form a maps of HIF scores with a 0–300 range. The IVIM and R2* Mapping images were processed to create maps of the D, D*, f and R2* that were then paired with the corresponding HIF score maps. The average D, D*, f, perfusion (f × D*) and R2* values were calculated for the ROIs in the tumor and normal brain regions with different HIF-1α levels and used in further analysis. In this study, the average tumor size of sixteen C6 model rats was 458 ± 46.52 mm³, and the 482 included ROIs consisted of 280 tumoral and 202 normal ROIs. The average HIF score for the tumor regions was significantly higher than normal brain tissue (p < 0.001), and higher HIF scores were obtained for the central part of tumors than peripheral parts (p=0.03). Compared with normal brain tissues, elevated perfusion and f values were observed in tumor regions (p = 0.021, 0.004). In tumoral ROIs, the R2* values were higher in the group with high HIF-1α expression than in the group with low HIF-1α expression (p = 0.003). A correlation analysis revealed a positive correlation between the R2* value and HIF scores (r = 0.43, p < 0.001) and a negative correlation between D* and the HIF scores (r = -0.30, p = 0.001). Discrepancies in HIF-1α expression were found among different intratumoral areas, and IVIM and R2* Mapping were found to be promising means of noninvasive detection of the distribution and expression level of HIF-1α.

MCL1 as putative target in pancreatoblastoma

Pancreatoblastoma (PB) is a rare tumor of the pancreas. In case of metastases, the treatment options are sparse and targeted approaches are not developed. We here evaluate MCL1 amplification as a putative target in PB.

Thirteen samples from adult (10/13) and pediatric patients (3/13) were collected. Three of these samples had been previously subjected to whole-exome sequencing (2 cases) or whole-genome sequencing (1 case) within a precision oncology program (NCT/DKTK MASTER), and this analysis had shown copy number gains of MCL1 gene. We established a fluorescence in situ hybridization (FISH) test to assess the copy number alterations of MCL1 gene in 13 formalin-fixed paraffin-embedded PBs, including the 3 cases assessed by genome sequencing. FISH analysis showed the amplification of MCL1 in 2 cases (both were adult PB), one of which was a case with the highest copy number gain at genomic analysis. In both cases, the average gene copy number per cell was ≥ 5.7 and the MCL1/1p12 ratio was ≥ 2.4. Our data support MCL1 as a putative target in PB. Patients with MCL1-amplified PB might benefit from MCL1 inhibition. Sequencing data is useful to screen for amplification; however, the established FISH for MCL1 can help to determine the level and cellular heterogeneity of MCL1 amplification more accurately.

Synthetic lethality of cyclin-dependent kinase inhibitor Dinaciclib with VHL-deficiency allows for selective targeting of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (CC-RCC) remains one of the most deadly forms of kidney cancer despite recent advancements in targeted therapeutics, including tyrosine kinase and immune checkpoint inhibitors. Unfortunately, these therapies have not been able to show better than a 16% complete response rate. In this study we evaluated a cyclin-dependent kinase inhibitor, Dinaciclib, as a potential new targeted therapeutic for CC-RCC. In vitro, Dinaciclib showed anti-proliferative and pro-apoptotic effects on CC-RCC cell lines in Cell Titer Glo, Crystal Violet, FACS-based cell cycle analysis, and TUNEL assays. Additionally, these responses were accompanied by a reduction in phospho-Rb and pro-survival MCL-1 cell signaling responses, as well as the induction of caspase 3 and PARP cleavage. In vivo, Dinaciclib efficiently inhibited primary tumor growth in an orthotopic, patient-derived xenograft-based CC-RCC mouse model. Importantly, Dinaciclib targeted both CD105⁺ cancer stem cells (CSCs) and CD105⁻ non-CSCs in vivo. Moreover, normal cell lines, as well as a CC-RCC cell line with re-expressed von-Hippel Lindau (VHL) tumor suppressor gene, were protected from Dinaciclib-induced cytotoxicity when not actively dividing, indicating an effective therapeutic window due to synthetic lethality of Dinaciclib treatment with VHL loss. Thus, Dinaciclib represents a novel potential therapeutic for CC-RCC.

Killing SCLC: insights into how to target a shapeshifting tumor

Small cell lung cancer (SCLC) is a rapidly growing, highly metastatic, and relatively immune-cold lung cancer subtype. Historically viewed in the laboratory and clinic as a single disease, new discoveries suggest that SCLC comprises multiple molecular subsets. Expression of MYC family members and lineage-related transcription factors ASCL1, NEUROD1, and POU2F3 (and, in some studies, YAP1) define unique molecular states that have been associated with distinct responses to a variety of therapies. However, SCLC tumors exhibit a high degree of intratumoral heterogeneity, with recent studies suggesting the existence of tumor cell plasticity and phenotypic switching between subtype states. While SCLC plasticity is correlated with, and likely drives, therapeutic resistance, the mechanisms underlying this plasticity are still largely unknown. Subtype states are also associated with immune-related gene expression, which likely impacts response to immune checkpoint blockade and may reveal novel targets for alternative immunotherapeutic approaches. In this review, we synthesize recent discoveries on the mechanisms of SCLC plasticity and how these processes may impinge on antitumor immunity.

Computational design of an apoptogenic protein that binds BCL-xL and MCL-1 simultaneously and potently

One of the hallmarks of cancer cells is their ability to evade apoptosis, which confers survival advantages and resistance to anti-cancer drugs. Cancers often exhibit overexpression of anti-apoptotic BCL-2 proteins, the loss of which triggers apoptosis. In particular, the inhibition of both BCL-xL and MCL-1, but neither one individually, synergistically enhances apoptotic cell death. Here, we report computational design to produce a protein that inhibits both BCL-xL and MCL-1 simultaneously. To a reported artificial three-helix bundle whose second helix was designed to bind MCL-1, we added a fourth helix and designed it to bind BCL-xL. After structural validation of the design and further structure-based sequence design, we produced a dual-binding protein that interacts with both BCL-xL and MCL-1 with apparent dissociation constants of 820 pM and 196 pM, respectively. Expression of this dual binder in a subset of cancer cells induced apoptotic cell death at levels significantly higher than those induced by the pro-apoptotic BIM protein. With a genetic fusion of a mitochondria-targeting sequence or the BH3 sequence of BIM, the activity of the dual binder was enhanced even further. These data suggest that targeted delivery of this dual binder alone or as a part of a modular protein to cancers in the form of protein, mRNA, or DNA may be an effective way to induce cancer cell apoptosis.

Targeting the Intrinsic Apoptosis Pathway: A Window of Opportunity for Prostate Cancer

Despite major improvements in the management of advanced prostate cancer over the last 20 years, the disease remains invariably fatal, and new effective therapies are required. The development of novel hormonal agents and taxane chemotherapy has improved outcomes, although primary and acquired resistance remains problematic. Inducing cancer cell death via apoptosis has long been an attractive goal in the treatment of cancer. Apoptosis, a form of regulated cell death, is a highly controlled process, split into two main pathways (intrinsic and extrinsic), and is stimulated by a multitude of factors, including cellular and genotoxic stress. Numerous therapeutic strategies targeting the intrinsic apoptosis pathway are in clinical development, and BH3 mimetics have shown promising efficacy for hematological malignancies. Utilizing these agents for solid malignancies has proved more challenging, though efforts are ongoing. Molecular characterization and the development of predictive biomarkers is likely to be critical for patient selection, by identifying tumors with a vulnerability in the intrinsic apoptosis pathway. This review provides an up-to-date overview of cell death and apoptosis, specifically focusing on the intrinsic pathway. It summarizes the latest approaches for targeting the intrinsic apoptosis pathway with BH3 mimetics and discusses how these strategies may be leveraged to treat prostate cancer.

Functional apoptosis profiling identifies MCL-1 and BCL-xL as prognostic markers and therapeutic targets in advanced thymomas and thymic carcinomas

BACKGROUND

Multi-omics studies have shown a high and lack of common driver mutations in most thymomas (TH) and thymic carcinomas (TC) that hamper the development of novel treatment approaches. However, deregulation of apoptosis has been proposed as a common hallmark of TH and TC. BH3 profiling can be utilized to study the readiness of living cancer cells to undergo apoptosis and their dependency on pro-survival BCL-2 family proteins.

METHODS

We screened a cohort of 62 TH and TC patient samples for expression of BCL-2 family proteins and used the TC cell line 1889c and native TH for dynamic BH3 profiling and treatment with BH3 mimetics.

RESULTS

Immunohistochemical overexpression of MCL-1 and BCL-xL was a strong prognostic marker of TH and TC, and BH3 profiling indicated a strong dependency on MCL-1 and BCL-xL in TH. Single inhibition of MCL-1 resulted in increased binding of BIM to BCL-xL as an escape mechanism that the combined inhibition of both factors could overcome. Indeed, the inhibition of MCL-1 and BCL-xL in combination induced apoptosis in a caspase-dependent manner in untreated and MCL-1-resistant 1889c cells.

CONCLUSION

TH and TC are exquisitely dependent on the pro-survival factors MCL-1 and BCL-xL, making them ideal candidates for co-inhibition by BH3 mimetics. Since TH show a heterogeneous dependency on BCL-2 family proteins, upfront BH3 profiling could select patients and tailor the optimal therapy with the least possible toxicity.

MicroRNAs Involved in Small-cell Lung Cancer as Possible Agents for Treatment and Identification of New Targets

Small-cell lung cancer, a neuro-endocrine type of lung cancers, responds very well to chemotherapy-based agents. However, a high frequency of relapse due to adaptive resistance is observed. Immunotherapy-based treatments with checkpoint inhibitors has resulted in improvement of treatment but the responses are not as impressive as in other types of tumor. Therefore, identification of new targets and treatment modalities is an important issue. After searching the literature, we identified eight down-regulated microRNAs involved in radiation- and chemotherapy-induced resistance, as well as three up-regulated and four down-regulated miRNAs with impacts on proliferation, invasion and apoptosis of small-cell lung cancer cells in vitro. Furthermore, one up-regulated and four down-regulated microRNAs with in vivo activity in SCLC cell xenografts were identified. The identified microRNAs are candidates for inhibition or reconstitution therapy. The corresponding targets are candidates for inhibition or functional reconstitution with antibody-based moieties or small molecules.

Myeloid cell leukemia 1 (MCL-1): Structural characteristics and application in cancer therapy

Apoptosis, a major hallmark of cancer cells, regulates cellular fate and homeostasis. BCL-2 (B-cell CLL/Lymphoma 2) protein family is popularly known to mediate the intrinsic mode of apoptosis, of which MCL-1 is a crucial member. Myeloid cell leukemia 1 (MCL-1) is an anti-apoptotic oncoprotein and one of the most investigated members of the BCL-2 family. It is commonly known to be genetically altered, aberrantly overexpressed, and primarily associated with drug resistance in various human cancers. Recent advancements in the development of selective MCL-1 inhibitors and evaluating their effectiveness in cancer treatment establish its popularity as a molecular target. The overall aim is the selective induction of apoptosis in cancer cells by using a single or combination of BCL-2 family inhibitors. Delineating the precise molecular mechanisms associated with MCL-1-mediated cancer progression will certainly improve the efficacy of clinical interventions aimed at MCL-1 and hence patient survival. This review is structured to highlight the structural characteristics of MCL-1, its specific interactions with NOXA, MCL-1-regulatory microRNAs, and at the same time focus on the emerging therapeutic strategies targeting our protein of interest (MCL-1), alone or in combination with other treatments.

The role of endolysosomal trafficking in anticancer drug resistance

Multidrug resistance (MDR) remains a major obstacle towards curative treatment of cancer. Despite considerable progress in delineating the basis of intrinsic and acquired MDR, the underlying molecular mechanisms remain to be elucidated. Emerging evidences suggest that dysregulation in endolysosomal compartments is involved in mediating MDR through multiple mechanisms, such as alterations in endosomes, lysosomes and autophagosomes, that traffic and biodegrade the molecular cargo through macropinocytosis, autophagy and endocytosis. For example, altered lysosomal pH, in combination with transcription factor EB (TFEB)-mediated lysosomal biogenesis, increases the sequestration of hydrophobic anti-cancer drugs that are weak bases, thereby producing an insufficient and off-target accumulation of anti-cancer drugs in MDR cancer cells. Thus, the use of well-tolerated, alkalinizing compounds that selectively block Vacuolar H⁺-ATPase (V-ATPase) may be an important strategy to overcome MDR in cancer cells and increase chemotherapeutic efficacy. Other mechanisms of endolysosomal-mediated drug resistance include increases in the expression of lysosomal proteases and cathepsins that are involved in mediating carcinogenesis and chemoresistance. Therefore, blocking the trafficking and maturation of lysosomal proteases or direct inhibition of cathepsin activity in the cytosol may represent novel therapeutic modalities to overcome MDR. Furthermore, endolysosomal compartments involved in catabolic pathways, such as macropinocytosis and autophagy, are also shown to be involved in the development of MDR. Here, we review the role of endolysosomal trafficking in MDR development and discuss how targeting endolysosomal pathways could emerge as a new therapeutic strategy to overcome chemoresistance in cancer.

Targeting Bcl-2 Family Proteins: What, Where, When?

Proteins of the Bcl-2 family are known as regulators of apoptosis, one of the most studied forms of programmed cell death. The Bcl-2 protein family is represented by both pro- and antiapoptotic members. Antiapoptotic proteins are often exploited by tumor cells to avoid their death, thus playing an important role in carcinogenesis and in acquisition of resistance to various therapeutic agents. Therefore, antiapoptotic proteins represent attractive targets for cancer therapy. A detailed investigation of interactions between Bcl-2 family proteins resulted in the development of highly selective inhibitors of individual antiapoptotic members. These agents are currently being actively studied at the preclinical and clinical stages and represent a promising therapeutic strategy, which is highlighted by approval of venetoclax, a selective inhibitor of Bcl-2, for medical use. Meanwhile, inhibition of antiapoptotic Bcl-2 family proteins has significant therapeutic potential that is yet to be revealed. In the coming era of precision medicine, a detailed study of the mechanisms responsible for the sensitivity or resistance of tumor cells to various therapeutic agents, as well as the search for the most effective combinations, is of great importance. Here, we discuss mechanisms of how the Bcl-2 family proteins function, principles of their inhibition by small molecules, success of this approach in cancer therapy, and, eventually, biochemical features that can be exploited to improve the use of Bcl-2 family inhibitors as anticancer drugs.

Novel gene signatures for stage classification of the squamous cell carcinoma of the lung

The squamous cell carcinoma of the lung (SCLC) is one of the most common types of lung cancer. As GLOBOCAN reported in 2018, lung cancer was the first cause of death and new cases by cancer worldwide. Typically, diagnosis is made in the later stages of the disease with few treatment options available. The goal of this work was to find some key components underlying each stage of the disease, to help in the classification of tumor samples, and to increase the available options for experimental assays and molecular targets that could be used in treatment development. We employed two approaches. The first was based in the classic method of differential gene expression analysis, network analysis, and a novel concept known as network gatekeepers. The second approach was using machine learning algorithms. From our combined approach, we identified two sets of genes that could function as a signature to identify each stage of the cancer pathology. We also arrived at a network of 55 nodes, which according to their biological functions, they can be regarded as drivers in this cancer. Although biological experiments are necessary for their validation, we proposed that all these genes could be used for cancer development treatments.

MCL-1 inhibitors, fast-lane development of a new class of anti-cancer agents

Cell death escape is one of the most prominent features of tumor cells and closely linked to the dysregulation of members of the Bcl-2 family of proteins. Among those, the anti-apoptotic family member myeloid cell leukemia-1 (MCL-1) acts as a master regulator of apoptosis in various human malignancies. Irrespective of its unfavorable structure profile, independent research efforts recently led to the generation of highly potent MCL-1 inhibitors that are currently evaluated in clinical trials. This offers new perspectives to target a so far undruggable cancer cell dependency. However, a detailed understanding about the tumor and tissue type specific implications of MCL-1 are a prerequisite for the optimal (i.e., precision medicine guided) use of this novel drug class. In this review, we summarize the major functions of MCL-1 with a special focus on cancer, provide insights into its different roles in solid vs. hematological tumors and give an update about the (pre)clinical development program of state-of-the-art MCL-1 targeting compounds. We aim to raise the awareness about the heterogeneous role of MCL-1 as drug target between, but also within tumor entities and to highlight the importance of rationale treatment decisions on a case by case basis.

A novel kinase inhibitor, LZT-106, downregulates Mcl-1 and sensitizes colorectal cancer cells to BH3 mimetic ABT-199 by targeting CDK9 and GSK-3β signaling

Colorectal cancer (CRC) is one of the most common malignancies worldwide and is associated with poor prognosis and high mortality. Despite advances in treatment with chemotherapy, CRC remains a major cause of drug resistance-related cancer deaths. One of the main reasons for such resistance is dysregulation of Mcl-1 expression. In this study, we identified LZT-106 as a novel kinase inhibitor that was able to bind to CDK9 with potent inhibitory ability, and indirectly regulate the expression of Mcl-1. However, different regulatory profiles were observed between LZT-106 and the well-studied CDK9 inhibitor flavopiridol with regards to Mcl-1 inhibition. Via Western blotting, real-time PCR and immunoprecipitation, we confirmed that LZT-106 was also able to target GSK-3β signaling and facilitate the degradation of Mcl-1. And LZT-106 was shown to synergize with ABT-199 to induce apoptosis even in the RKO cell line that overexpressed Mcl-1. Finally, LZT-106 significantly inhibited tumor growth in a xenograft mouse model with minimal toxicity. Overall, our findings suggest that LZT-106 is a promising candidate drug for the treatment of patients with CRC.

Chemo-photodynamic therapy by pulmonary delivery of gefitinib nanoparticles and 5-aminolevulinic acid for treatment of primary lung cancer of rats

Lung cancer is a severe disease with high mortality. Chemotherapy is one major treatment for lung cancer. However, systemic chemotherapeutics usually distribute throughout the body without specific lung distribution so that serious side effects are unavoidable. Photodynamic therapy (PDT) is occasionally used for lung cancer treatment but photosensitizers are also systemically administered and the bronchoscopic intervention under anesthesia may hurt lung tissues. Here, we combined inhaled chemotherapeutics and photosensitizers for chemo-photodynamic therapy (CPDT) of primary lung cancer of rats with external laser light irradiation. Gefitinib PLGA nanoparticles (GNPs) were prepared. The anti-cancer effects of GNPs and/or a common photosensitizer 5-aminolevulinic acid (5-ALA) were explored on A549 cells (adenocarcinomic human alveolar basal epithelial cells) and primary lung cancer rats after intratracheal administration. External light irradiation was applied due to its higher safety compared to internal light irradiation that may result in injuries after a laser optic fiber was intubated into the lung. The remarkable synergistic effect of CPDT was confirmed although the single therapies were also effective, where the high anti-lung cancer effects were shown and some typical lung cancer markers, including CD31, VEGF, NF-κB p65 and Bcl-2, significantly decreased. Moreover, the treatments attenuated inflammation with the downregulation of TNF-α. The combination of pulmonary drug delivery and chemo-photodynamic therapy is a promising strategy for treatment of lung cancer.