Integrative molecular and clinical profiling of acral melanoma links focal amplification of 22q11.21 to metastasis

Integrative molecular and spatial analysis reveals evolutionary dynamics and tumor-immune interplay of in situ and invasive acral melanoma

In acral melanoma (AM), progression from in situ (AMis) to invasive AM (iAM) leads to significantly reduced survival. However, evolutionary dynamics during this process remain elusive. Here, we report integrative molecular and spatial characterization of 147 AMs using genomics, bulk and single-cell transcriptomics, and spatial transcriptomics and proteomics. Vertical invasion from AMis to iAM displays an early and monoclonal seeding pattern. The subsequent regional expansion of iAM exhibits two distinct patterns, clonal expansion and subclonal diversification. Notably, molecular subtyping reveals an aggressive iAM subset featured with subclonal diversification, increased epithelial-mesenchymal transition (EMT), and spatial enrichment of APOE+/CD163+ macrophages. In vitro and ex vivo experiments further demonstrate that APOE+CD163+ macrophages promote tumor EMT via IGF1-IGF1R interaction. Adnexal involvement can predict AMis with higher invasive potential whereas APOE and CD163 serve as prognostic biomarkers for iAM. Altogether, our results provide implications for the early detection and treatment of AM.

Melanoma-Derived DNA Polymerase Theta Variants Exhibit Altered DNA Polymerase Activity

DNA polymerase θ (Pol θ or POLQ) is primarily involved in repairing double-stranded breaks in DNA through an alternative pathway known as microhomology-mediated end joining (MMEJ) or theta-mediated end joining (TMEJ). Unlike other DNA repair polymerases, Pol θ is thought to be highly error-prone yet critical for cell survival. We have identified several POLQ gene variants from human melanoma tumors that experience altered DNA polymerase activity, including a propensity for incorrect nucleotide selection and reduced polymerization rates compared to WT Pol θ. Variants are 30-fold less efficient at incorporating a nucleotide during repair and up to 70-fold less accurate at selecting the correct nucleotide opposite a templating base. This suggests that aberrant Pol θ has reduced DNA repair capabilities and may also contribute to increased mutagenesis. Moreover, the variants were identified in established tumors, suggesting that cancer cells may use mutated polymerases to promote metastasis and drug resistance.

Circulating Tumor Reactive KIR+CD8+ T cells Suppress Anti-Tumor Immunity in Patients with Melanoma

Effective anti-tumor immunity is largely driven by cytotoxic CD8+ T cells that can specifically recognize tumor antigens. However, the factors which ultimately dictate successful tumor rejection remain poorly understood. Here we identify a subpopulation of CD8+ T cells which are tumor antigen-specific in patients with melanoma but resemble KIR+CD8+ T cells with a regulatory function (Tregs). These tumor antigen-specific KIR+CD8+ T cells are detectable in both the tumor and the blood, and higher levels of this population are associated with worse overall survival. Our findings therefore suggest that KIR+CD8+ Tregs are tumor antigen-specific but uniquely suppress anti-tumor immunity in patients with melanoma.

ERK hyperactivation serves as a unified mechanism of escape in intrinsic and acquired CDK4/6 inhibitor resistance in acral lentiginous melanoma

Patients with metastatic acral lentiginous melanoma (ALM) suffer worse outcomes relative to patients with other forms of cutaneous melanoma (CM), and do not benefit as well to approved melanoma therapies. Identification of cyclin-dependent kinase 4 and 6 (CDK4/6) pathway gene alterations in >60% of ALMs has led to clinical trials of the CDK4/6 inhibitor (CDK4i/6i) palbociclib for ALM; however, median progression free survival with CDK4i/6i treatment was only 2.2 months, suggesting existence of resistance mechanisms. Therapy resistance in ALM remains poorly understood; here we report hyperactivation of MAPK signaling and elevated cyclin D1 expression serve as a mechanism of intrinsic early/adaptive CDK4i/6i resistance. ALM cells that have acquired CDK4i/6i resistance following chronic treatment exposure also exhibit hyperactivation of the MAPK pathway. MEK and/or ERK inhibition increases CDK4i/6i efficacy against therapy naïve and CDK4i/6i-resistant AM cells in xenograft and patient-derived xenograft (PDX) models and promotes a defective DNA repair, cell cycle arrested and apoptotic program. Notably, gene alterations poorly correlate with protein expression of cell cycle proteins in ALM or efficacy of CDK4i/6i, urging additional strategies when stratifying patients for CDK4i/6i trial inclusion. Concurrent targeting of the MAPK pathway and CDK4/6 represents a new approach for patients with metastatic ALM to improve outcomes.

Delineating the early dissemination mechanisms of acral melanoma by integrating single-cell and spatial transcriptomic analyses

Acral melanoma (AM) is a rare subtype of melanoma characterized by a high incidence of lymph node (LN) metastasis, a critical factor in tumor dissemination and therapeutic decision-making. Here, we employ single-cell and spatial transcriptomic analyses to investigate the dynamic evolution of early AM dissemination. Our findings reveal substantial inter- and intra-tumor heterogeneity in AM, alongside a highly immunosuppressive tumor microenvironment and complex intercellular communication networks, particularly in patients with LN metastasis. Notably, we identify a strong association between MYC+ Melanoma (MYC+MEL) and FGFBP2+NKT cells with LN metastasis. Furthermore, we demonstrate that LN metastasis requires a metabolic shift towards fatty acid oxidation (FAO) induced by MITF in MYC+MEL cells. Etomoxir, a clinically approved FAO inhibitor, can effectively suppress MITF-mediated LN metastasis. This comprehensive dataset enhances our understanding of LN metastasis in AM, and provides insights into the potential therapeutic targeting for the management of early AM dissemination.

Acral melanoma: new insights into the immune and genomic landscape

Acral melanoma is a rare subtype of melanoma that arises on the non-hair bearing skin of the nail bed, palms of the hand and soles of the feet. It is unique among melanomas in not being linked to ultraviolet radiation (UVR) exposure from the sun, and, as such, its incidence is similar across populations who are of Asian, Hispanic, African and European origin. Although research into acral melanoma has lagged behind that of sun-exposed cutaneous melanoma, recent studies have begun to address the unique genetics and immune features of acral melanoma. In this review we will discuss the latest progress in understanding the biology of acral melanoma across different ethnic populations and will outline how these new discoveries can help to guide the therapeutic management of this rare tumor.

Melanoma-derived DNA polymerase theta variants exhibit altered DNA polymerase activity

DNA Polymerase θ (Pol θ or POLQ) is primarily involved in repairing double-stranded breaks in DNA through the alternative pathway known as microhomology-mediated end joining (MMEJ) or theta-mediated end joining (TMEJ). Unlike other DNA repair polymerases, Pol θ is thought to be highly error prone, yet critical for cell survival. We have identified several mutations in the POLQ gene from human melanoma tumors. Through biochemical analysis, we have demonstrated that all three cancer-associated variants experienced altered DNA polymerase activity including a propensity for incorrect nucleotide selection and reduced polymerization rates compared to WT Pol θ. Moreover, the variants are 30 fold less efficient at incorporating a nucleotide during repair and up to 70 fold less accurate at selecting the correct nucleotide opposite a templating base. Taken together, this suggests that aberrant Pol θ has reduced DNA repair capabilities and may also contribute to increased mutagenesis. While this may be beneficial to normal cell survival, the variants were identified in established tumors suggesting that cancer cells may use this promiscuous polymerase to its advantage to promote metastasis and drug resistance.

Association of NRAS mutations and tertiary lymphoid structure formation with clinical outcomes of adjuvant PD-1 inhibitors for acral melanoma

OBJECTIVES

This study evaluates the efficacy of programmed death-1 (PD-1) inhibitors as adjuvant therapy for acral melanoma (AM) and the predictive value of genetic mutations and tertiary lymphoid structures (TLSs).

METHODS AND RESULTS

A single-center retrospective longitudinal cohort study was conducted between October 1, 2018, and September 31, 2022. Patients with stages II-III completely resected AM were treated with at least two doses of adjuvant PD-1 inhibitors. A total of 44 participants were included in the final analysis, of which 41 patients with stage III. The median follow-up time, median relapse-free survival (RFS), and median distance metastasis-free survival (DMFS) for all patients were 18.4 months, 21.6 months, and 30.6 months, respectively. 21 (47.7%) and 20 (45.5%) patients were intravenously administered pembrolizumab and toripalimab, respectively. There were no significant differences in RFS (24.4 months vs. 18.9 months, p = 0.432) or DMFS (30.6 months vs. not reached, p = 0.865) between the pembrolizumab and toripalimab groups, respectively. The median DMFS (41.1 months vs. 9.0 months, p < 0.001) in the wild-type NRAS group was significantly longer than that in the NRAS mutation group. Overall, different levels of TLSs infiltration did not significantly affect patient survival. Only three people discontinued treatment due to adverse events. No treatment-related death occurred during the study period.

CONCLUSION

Our study suggests that adjuvant toripalimab and pembrolizumab therapy have comparable efficacies in patients with AM and are both well tolerated. Adjuvant monotherapy with PD-1 inhibitors may not be appropriate for AM with NRAS mutations.

LZTR1 deficiency exerts high metastatic potential by enhancing sensitivity to EMT induction and controlling KLHL12-mediated collagen secretion

Leucine zipper-like transcriptional regulator 1 (LZTR1), a substrate adaptor of Cullin 3 (CUL3)-based E3 ubiquitin ligase, regulates proteostasis of the RAS subfamily. Mutations in LZTR1 have been identified in patients with several types of cancer. However, the role of LZTR1 in tumor metastasis and the target molecules of LZTR1, excluding the RAS subfamily, are not clearly understood. Here, we show that LZTR1 deficiency increases tumor growth and metastasis. In lung adenocarcinoma cells, LZTR1 deficiency induced the accumulation of the RAS subfamily and enhanced cell proliferation, invasion, and xenograft tumor growth. Multi-omics analysis to clarify the pathways related to tumor progression showed that MAPK signaling, epithelial-mesenchymal transition (EMT), and extracellular matrix (ECM) remodeling-related gene ontology terms were enriched in LZTR1 knockout cells. Indeed, LZTR1 deficiency induced high expression of EMT markers under TGF-β1 treatment. Our search for novel substrates that interact with LZTR1 resulted in the discovery of a Kelch-like protein 12 (KLHL12), which is involved in collagen secretion. LZTR1 could inhibit KLHL12-mediated ubiquitination of SEC31A, a component of coat protein complex II (COPII), whereas LZTR1 deficiency promoted collagen secretion. LZTR1-RIT1 and LZTR1-KLHL12 worked independently regarding molecular interactions and did not directly interfere with each other. Further, we found that LZTR1 deficiency significantly increases lung metastasis and promotes ECM deposition around metastatic tumors. Since collagen-rich extracellular matrix act as pathways for migration and facilitate metastasis, increased expression of RAS and collagen deposition may exert synergistic or additive effects leading to tumor progression and metastasis. In conclusion, LZTR1 deficiency exerts high metastatic potential by enhancing sensitivity to EMT induction and promoting collagen secretion. The functional inhibition of KLHL12 by LZTR1 provides important evidence that LZTR1 may be a repressor of BTB-Kelch family members. These results provide clues to the mechanism of LZTR1-deficiency carcinogenesis.

Integrated exome sequencing and microarray analyses detected genetic defects and underlying pathways of hepatocellular carcinoma

We performed whole exome sequencing (WES) and microarray analysis to detect somatic variants and copy number alterations (CNAs) for underlying mechanisms in a case series of hepatocellular carcinoma (HCC) with paired DNA samples from tumor and adjacent nontumor tissues. Clinicopathologic findings based on Edmondson-Steiner (E-S) grading, Barcelona-Clinic Liver Cancer (BCLC) stages, recurrence, and survival status and their associations with tumor mutation burden (TMB) and CNA burden (CNAB) were evaluated. WES from 36 cases detected variants in the TP53, AXIN1, CTNNB1, and SMARCA4 genes, amplifications of the AKT3, MYC, and TERT genes, and deletions of the CDH1, TP53, IRF2, RB1, RPL5, and PTEN genes. These genetic defects affecting the p53/cell cycle control, PI3K/Ras, and β-catenin pathways were observed in approximately 80% of cases. A germline variant in the ALDH2 gene was detected in 52% of the cases. Significantly higher CNAB in patients with poor prognosis by E-S grade III, BCLC stage C, and recurrence than patients with good prognosis by grade III, stage A, grade III and nonrecurrence was noted. Further analysis on a large case series to correlate genomic profiling with clinicopathologic classifications could provide evidence for diagnostic interpretation, prognostic prediction, and target intervention on involved genes and pathways.

Genomic and transcriptional characterization of early esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a highly heterogeneous cancer that lacks comprehensive understanding and effective treatment. Although multi-omics study has revealed features and underlying drivers of advanced ESCC, research on molecular characteristics of the early stage ESCC is quite limited.

MATERIALS AND METHODS

We presented characteristics of genomics and transcriptomics in 10 matched pairs of tumor and normal tissues of early ESCC patients in the China region.

RESULTS

We identified the specific patterns of cancer gene mutations and copy number variations. We also found a dramatic change in the transcriptome, with more than 4,000 genes upregulated in cancer. Among them, more than one-third of HOX family genes were specifically and highly expressed in early ESCC samples of China and validated by RT-qPCR. Gene regulation network analysis indicated that alteration of Hox family genes promoted the proliferation and metabolism remodeling of early ESCC.

CONCLUSIONS

We characterized the genomic and transcriptomic landscape of 10 paired normal adjacent and early ESCC tissues in the China region, and provided a new perspective to understand the development of ESCC and insight into potential prevention and diagnostic targets for the management of early ESCC in China.

Inhibiting SCD expression by IGF1R during lorlatinib therapy sensitizes melanoma to ferroptosis

Induction of ferroptosis is an emerging strategy to suppress melanoma progression. Strategies to enhance the sensitivity to ferroptosis induction would be a major advance in melanoma therapy. Here, we used a drug synergy screen that combined a ferroptosis inducer, RSL3, with 240 anti-tumor drugs from the FDA-approved drug library and identified lorlatinib to synergize with RSL3 in melanoma cells. We further demonstrated that lorlatinib sensitized melanoma to ferroptosis through inhibiting PI3K/AKT/mTOR signaling axis and its downstream SCD expression. Moreover, we found that lorlatinib's target IGF1R, but not ALK or ROS1, was the major mediator of lorlatinib-mediated sensitivity to ferroptosis through targeting PI3K/AKT/mTOR signaling axis. Finally, lorlatinib treatment sensitized melanoma to GPX4 inhibition in preclinical animal models, and melanoma patients with low GPX4 and IGF1R expression in their tumors survived for longer period. Altogether, lorlatinib sensitizes melanoma to ferroptosis by targeting IGF1R-mediated PI3K/AKT/mTOR signaling axis, suggesting that combination with lorlatinib could greatly expand the utility of GPX4 inhibition to melanoma patients with IGF1R-proficient expression.

ERK Hyperactivation Serves as a Unified Mechanism of Escape in Intrinsic and Acquired CDK4/6 Inhibitor Resistance in Acral Lentiginous Melanoma

Patients with metastatic acral lentiginous melanoma (ALM) suffer worse outcomes relative to patients with other forms of cutaneous melanoma (CM), and do not benefit as well to approved melanoma therapies. Identification of cyclin-dependent kinase 4 and 6 (CDK4/6) pathway gene alterations in > 60% of ALMs has led to clinical trials of the CDK4/6 inhibitor (CDK4i/6i) palbociclib for ALM; however, median progression free survival with CDK4i/6i treatment was only 2.2 months, suggesting existence of resistance mechanisms. Therapy resistance in ALM remains poorly understood; here we report hyperactivation of MAPK signaling and elevated cyclin D1 expression are a unified mechanism of both intrinsic and acquired CDK4i/6i resistance. MEK and/or ERK inhibition increases CDK4i/6i efficacy in a patient-derived xenograft (PDX) model of ALM and promotes a defective DNA repair, cell cycle arrested and apoptotic program. Notably, gene alterations poorly correlate with protein expression of cell cycle proteins in ALM or efficacy of CDK4i/6i, urging additional strategies when stratifying patients for CDK4i/6i trial inclusion. Concurrent targeting of the MAPK pathway and CDK4/6 represents a new approach to improve outcomes for patients with advanced ALM.

Impact of response patterns for patients with advanced acral melanoma treated with anti-programmed death-1 monotherapy

BACKGROUND

Acral melanoma (AM) is less responsive to immunotherapy than nonacral cutaneous melanoma. Variable responses are seen during immunotherapy, including pseudoprogression, hyperprogressive disease (HPD) and heterogeneous responses. There are currently no studies on the response patterns of patients with AM treated with immunotherapy and the impact on the outcome.

OBJECTIVES

To evaluate the response patterns and prognosis of patients with AM treated with anti-programmed death (PD)-1 antibodies.

METHODS

Patients with advanced AM treated prospectively in five clinical trials of anti-PD-1 monotherapy at Peking University Cancer Hospital were included. Responses of individual metastases and heterogeneous responses were evaluated during immunotherapy. Cox proportional hazards regression analysis was conducted to identify the possible predictive factors and generate a nomogram to predict the risk of 1-year and 2-year mortality.

RESULTS

The overall response rate was 18·0%, the disease control rate was 36·1%, median progression-free survival was 3·5 months [95% confidence interval (CI) 1·7-5·3] and median overall survival was 17·5 months (95% CI 15·1-19·9) for anti-PD-1 monotherapy. Overall, 9·8% of patients met the criteria of HPD, and displayed a dramatically worse outcome than patients without HPD. In total, 369 metastatic lesions were assessed, with the highest response rate in lymph nodes (20·4%) and the lowest in the liver (5·6%). Homogeneous response, heterogeneous response and heterogeneous or homogeneous progression had different prognoses from the best to the worst. A predictive model was constructed and achieved good accuracy with a C-index of 0·73 (95% CI 0·63-0·84) in the training set and 0·74 (95% CI 0·61-0·86) in the validation set.

CONCLUSIONS

HPD during immunotherapy serves as an essential biomarker of poor prognosis in advanced AM. Metastases in different sites respond distinctively to immunotherapy. Clinically heterogeneous responses to immunotherapy affect the outcome of patients. A predictive model was built to distinguish the prognosis of acral melanoma under immunotherapy.

Clinical features, molecular pathology, and immune microenvironmental characteristics of acral melanoma

Acral melanoma (AM) has unique biology as an aggressive subtype of melanoma. It is a common subtype of melanoma in races with darker skin tones usually diagnosed at a later stage, thereby presenting a worse prognosis compared to cutaneous melanoma. The pathogenesis of acral melanoma differs from cutaneous melanoma, and trauma promotes its development. Compared to cutaneous melanomas, acral melanomas have a significantly lighter mutational burden with more copy number variants. Most acral melanomas are classified as triple wild-type. In contrast to cutaneous melanomas, acral melanomas have a suppressive immune microenvironment. Herein, we reviewed the clinical features, genetic variants, and immune microenvironmental characteristics of limbic melanomas to summarise their unique features.

Comprehensive Analysis of Genomic Alterations in Hepatoid Adenocarcinoma of the Stomach and Identification of Clinically Actionable Alterations

Simple Summary

Hepatoid adenocarcinoma of the stomach (HAS) is a subset of gastric cancer (GC) histologically characterized by hepatocellular carcinoma-like foci with or without alpha-fetoprotein secretion, which is easily misdiagnosed. Genomic alterations and potential targets for this population are still largely unknown. Additionally, treatment regimens of HAS are mainly based on GC guidelines, which is not reasonable for diseases with great heterogeneity. The present study comprehensively depicts the genomic features of HAS, and they are significantly different from GC, AFP-producing GC (AFPGC), and liver hepatocellular carcinoma (LIHC). Multiple aggressive behavior-related amplificated or deleted regions in HAS are firstly reported. Moreover, reliable and practicable clinically actionable alterations for HAS are identified, providing evidence for making personalized therapy based on the genomic characteristics of HAS instead of GC.

Abstract

Hepatoid adenocarcinoma of the stomach (HAS) is a rare malignancy with aggressive biological behavior. This study aimed to compare the genetic landscape of HAS with liver hepatocellular carcinoma (LIHC), gastric cancer (GC), and AFP-producing GC (AFPGC) and identify clinically actionable alterations. Thirty-eight cases of HAS were collected for whole-exome sequencing. Significantly mutated genes were identified. TP53 was the most frequently mutated gene (66%). Hypoxia, TNF-α/NFκB, mitotic spindle assembly, DNA repair, and p53 signaling pathways mutated frequently. Mutagenesis mechanisms in HAS were associated with spontaneous or enzymatic deamination of 5-methylcytosine to thymine and defective homologous recombination-related DNA damage repair. However, LIHC was characteristic of exposure to aflatoxin and aristolochic acid. The copy number variants (CNVs) in HAS was significantly different compared to LIHC, GC, and AFPGC. Aggressive behavior-related CNVs were identified, including local vascular invasion, advanced stages, and adverse prognosis. In 55.26% of HAS patients there existed at least one clinically actionable alteration, including ERBB2, FGFR1, CDK4, EGFR, MET, and MDM2 amplifications and BRCA1/2 mutations. MDM2 amplification with functional TP53 was detected in 5% of HAS patients, which was proved sensitive to MDM2 inhibitors. A total of 10.53% of HAS patients harbored TMB > 10 muts/Mb. These findings improve our understanding of the genomic features of HAS and provide potential therapeutic targets.

A novel ribosomal protein S6 kinase 2 inhibitor attenuates the malignant phenotype of cutaneous malignant melanoma cells by inducing cell cycle arrest and apoptosis

Malignant melanoma (MM) is a highly life-threatening tumor causing the majority of the cutaneous cancer-related deaths. Previously, ribosomal protein S6 kinase 2 (RSK2), the downstream effector of the MAPK pathway, represents a therapeutic target in melanoma. AE007 is discovered as a targeted RSK2 inhibitor, and subsequent results showed that AE007 inhibits RSK2 by directly binding to its protein kinase domain. AE007 causes cell cycle arrest and cellular apoptosis, thereby dramatically inhibiting proliferation, migration, and invasion of melanoma cells. Nevertheless, melanocytes and keratinocytes are not affected by this compound. In addition, suppression of RSK2 abrogates the inhibitory effect of AE007 on melanoma cell proliferation. AE007 treatment significantly inhibits the expression of Cyclin D1, Cyclin B1, CDK2, and Bcl-2, while raises the cleavage of PARP. Moreover, RNA sequencing results show that AE007 treatment can affect the genes expression profile, including the expression of cell cycle and DNA replication genes. In conclusion, AE007 is a promising melanoma therapeutic agent by targeting RSK2.

Anatomic position determines oncogenic specificity in melanoma

Oncogenic alterations to DNA are not transforming in all cellular contexts1,2. This may be due to pre-existing transcriptional programmes in the cell of origin. Here we define anatomic position as a major determinant of why cells respond to specific oncogenes. Cutaneous melanoma arises throughout the body, whereas the acral subtype arises on the palms of the hands, soles of the feet or under the nails3. We sequenced the DNA of cutaneous and acral melanomas from a large cohort of human patients and found a specific enrichment for BRAF mutations in cutaneous melanoma and enrichment for CRKL amplifications in acral melanoma. We modelled these changes in transgenic zebrafish models and found that CRKL-driven tumours formed predominantly in the fins of the fish. The fins are the evolutionary precursors to tetrapod limbs, indicating that melanocytes in these acral locations may be uniquely susceptible to CRKL. RNA profiling of these fin and limb melanocytes, when compared with body melanocytes, revealed a positional identity gene programme typified by posterior HOX13 genes. This positional gene programme synergized with CRKL to amplify insulin-like growth factor (IGF) signalling and drive tumours at acral sites. Abrogation of this CRKL-driven programme eliminated the anatomic specificity of acral melanoma. These data suggest that the anatomic position of the cell of origin endows it with a unique transcriptional state that makes it susceptible to only certain oncogenic insults.