Characterization of Wnt Signaling Pathway Aberrations in Metastatic Prostate Cancer.

Wnt-signaling pathway (WSP) alterations have been identified in patients with prostate cancer (PCa) and are implicated in disease progression and hormonal resistance. We utilized a multi-institutional dataset to characterize molecular alterations in the canonical and non-canonical WSP in PCa. Patients with PCa who underwent tissue-based genomic sequencing were investigated. Tumors with somatic activating mutations in CTNNB1 or RSPO2, or inactivating mutations in either APC or RNF43 were characterized as having aberrant canonical Wnt signaling (WSP-activated). Overall survival (OS) analyses were restricted to microsatellite stable (MSS) tumors lacking RNF43 G659fs* mutations. We also investigated non-canonical WSP by evaluation of ROR1, ROR2, and WNT5 in WSP-activated versus WSP wild-type (WSP-WT) tumors. Of 4,138 PCa samples, 3,684 were MSS. Among MSS tumors, 42.4% were from metastatic sites, of which 19.1% were WSP-activated, and 57.6% from the prostate, of which 10.1% were WSP-activated. WSP-activated tumors were more prevalent in metastatic sites than in primary PCa. WSP-activated PCa exhibited more SPOP mutations and higher expression of canonical WSP activators than WSP-WT tumors. ROR1 gene expression was elevated in WSP-activated tumors from both primary and metastatic sites. M2 macrophages predominated the tumor microenvironment in WSP-activated tumors. There was no significant difference in OS between WSP-activated and WSP-WT PCa patients. WSP-activated PCa demonstrated a more immunosuppressed tumor microenvironment and a pronounced upregulation of ROR1 gene expression, underscoring its potential involvement in the crosstalk between canonical and non-canonical Wnt signaling pathways. Implications: Our findings may provide rationale for developing novel therapeutic strategies targeting Wnt-activated PCa.

Pan-Cancer Interrogation of B7-H3 (CD276) as an Actionable Therapeutic Target Across Human Malignancies.

B7-H3 (CD276) is a transmembrane glycoprotein of the B7 immune checkpoint superfamily that has emerged as a promising therapeutic target. To better understand the applicability of B7-H3-directed therapies, we analyzed 156,791 samples comprising 50 cancer types to interrogate the clinical, genomic, transcriptomic, and immunologic correlates of B7-H3 mRNA expression. DNA (592-gene/whole-exome) and RNA (whole-transcriptome) sequencing was performed from samples submitted to Caris Life Sciences. B7-H3 high versus low expression was based on top and bottom quartiles for each cancer type. Patients' overall survival was determined from insurance claims data. Pathway analysis was performed using gene set enrichment analyses. Immune cell fractions were inferred using quanTIseq. B7-H3 is expressed across several human malignancies including prostate, pancreatic, ovarian, and lung cancers. High B7-H3 expression is associated with differences in overall survival, possibly indicating a prognostic role of B7-H3 for some cancers. When examining molecular features across all cancer types, we did not identify recurrent associations between B7-H3 expression and genetic alterations in TP53, RB1, and KRAS. However, we find consistent enrichment of epithelial-to-mesenchymal transition, Wnt, TGFß, and Notch signaling pathways. In addition, tumors with high B7-H3 expression are associated with greater proportions of M1 macrophages, but lower fractions of CD8+ T cells. We have begun to define the genomic, transcriptomic, clinical, and immunologic features associated with B7-H3 expression in 50 cancer types. We report novel clinical and molecular features of B7-H3-high tumors which may inform how current B7-H3 therapeutics should be deployed and prioritized. SIGNIFICANCE: B7-H3-targeting therapeutics have shown promising results in initial clinical trials. In this pan-cancer analysis of B7-H3 mRNA expression, we found that B7-H3 exhibits robust expression in many common cancer types. These results may inform further development of B7-H3-targeting therapeutics and may guide clinical decisions for patients with limited treatment options.

Characterization of FOLH1 Expression in Renal Cell Carcinoma.

PURPOSE: Given the emergence of PSMA-targeted diagnostic agents and therapeutics, we sought to investigate patterns of FOLH1 expression in RCC and their impacts on RCC outcomes. METHODS: We conducted a pooled multi-institutional analysis of patients with RCC having undergone DNA and RNA next-generation sequencing. FOLH1-high/low expression was defined as the ≥75th/<25th percentile of RNA transcripts per million (TPM). Angiogenic, T-effector, and myeloid expression signatures were calculated using previously defined gene sets. Kaplan-Meier estimates were calculated from the time of tissue collection or therapy start. RESULTS: We included 1,724 patients in the analysis. FOLH1 expression was significantly higher in clear cell (71%) compared to non-clear cell RCC tumors (19.0 versus 3.3 TPM, p < 0.001) and varied by specimen site (45% primary kidney/55% metastasis, 13.6 versus 9.9 TPM, p < 0.001). FOLH1 expression was correlated with angiogenic gene expression (Spearman = 0.76, p < 0.001) and endothelial cell abundance (Spearman = 0.76, p < 0.001). While OS was similar in patients with FOLH1-high versus -low ccRCC, patients with FOLH1-high clear cell tumors experienced a longer time on cabozantinib treatment (9.7 versus 4.6 months, respectively, HR 0.57, 95% CI 0.35-0.93, p < 0.05). CONCLUSIONS: We observed differential patterns of FOLH1 expression based on histology and tumor site in RCC. FOLH1 was correlated with angiogenic gene expression, increased OS, and a longer duration of cabozantinib treatment.

Mutational signature-based identification of DNA repair deficient gastroesophageal adenocarcinomas for therapeutic targeting.

Homologous recombination (HR) and nucleotide excision repair (NER) are the two most frequently disabled DNA repair pathways in cancer. HR-deficient breast, ovarian, pancreatic and prostate cancers respond well to platinum chemotherapy and PARP inhibitors. However, the frequency of HR deficiency in gastric and esophageal adenocarcinoma (GEA) still lacks diagnostic and functional validation. Using whole exome and genome sequencing data, we found that a significant subset of GEA, but very few colorectal adenocarcinomas, show evidence of HR deficiency by mutational signature analysis (HRD score). High HRD gastric cancer cell lines demonstrated functional HR deficiency by RAD51 foci assay and increased sensitivity to platinum chemotherapy and PARP inhibitors. Of clinical relevance, analysis of three different GEA patient cohorts demonstrated that platinum treated HR deficient cancers had better outcomes. A gastric cancer cell line with strong sensitivity to cisplatin showed HR proficiency but exhibited NER deficiency by two photoproduct repair assays. Single-cell RNA-sequencing revealed that, in addition to inducing apoptosis, cisplatin treatment triggered ferroptosis in a NER-deficient gastric cancer, validated by intracellular GSH assay. Overall, our study provides preclinical evidence that a subset of GEAs harbor genomic features of HR and NER deficiency and may therefore benefit from platinum chemotherapy and PARP inhibitors.

The Genomic, Transcriptomic, and Immunologic Landscape of HRAS Mutations in Solid Tumors.

Tipifarnib is the only targeted therapy breakthrough for HRAS-mutant (HRASmt) recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). The molecular profiles of HRASmt cancers are difficult to explore given the low frequency of HRASmt. This study aims to understand the molecular co-alterations, immune profiles, and clinical outcomes of 524 HRASmt solid tumors including urothelial carcinoma (UC), breast cancer (BC), non-small-cell lung cancer (NSCLC), melanoma, and HNSCC. HRASmt was most common in UC (3.0%), followed by HNSCC (2.82%), melanoma (1.05%), BC (0.45%), and NSCLC (0.44%). HRASmt was absent in Her2+ BC regardless of hormone receptor status. HRASmt was more frequently associated with squamous compared to non-squamous NSCLC (60% vs. 40% in HRASwt, p = 0.002). The tumor microenvironment (TME) of HRASmt demonstrated increased M1 macrophages in triple-negative BC (TNBC), HNSCC, squamous NSCLC, and UC; increased M2 macrophages in TNBC; and increased CD8+ T-cells in HNSCC (all p < 0.05). Finally, HRASmt was associated with shorter overall survival in HNSCC (HR: 1.564, CI: 1.16-2.11, p = 0.003) but not in the other cancer types examined. In conclusion, this study provides new insights into the unique molecular profiles of HRASmt tumors that may help to identify new targets and guide future clinical trial design.

Renal cell carcinoma histologic subtypes exhibit distinct transcriptional profiles.

Molecular profiling of clear cell renal cell carcinoma (ccRCC) tumors of patients in a clinical trial has identified distinct transcriptomic signatures with predictive value, yet data in non-clear cell variants (nccRCC) are lacking. We examined the transcriptional profiles of RCC tumors representing key molecular pathways, from a multi-institutional, real-world patient cohort, including ccRCC and centrally reviewed nccRCC samples. ccRCC had increased angiogenesis signature scores compared with the heterogeneous group of nccRCC tumors, while cell cycle, fatty acid oxidation/AMPK signaling, and fatty acid synthesis/pentose phosphate signature scores were increased in one or more nccRCC subtypes. Among both ccRCC and nccRCC tumors, T effector scores statistically correlated with increased immune cell infiltration and were more commonly associated with immunotherapy-related markers (PD-L1+/TMBhi/MSIhi). In conclusion, this study provides evidence of differential gene transcriptional profiles among ccRCC versus nccRCC tumors, providing insights for optimizing personalized and histology-specific therapeutic strategies for patients with advanced RCC.

Genomic and Transcriptomic Landscape of RET Wild-Type Medullary Thyroid Cancer and Potential Use of Mitogen-Activated Protein Kinase-Targeted Therapy.

BACKGROUND: About 75% of medullary thyroid cancers (MTCs) are sporadic with 45% to 70% being driven by a RET mutation. Selpercatinib is an approved treatment for RET-mutated (mut RET ) MTC; however, treatments are needed for wild-type RET MTC (wt RET ). Genomic alterations and transcriptomic signatures of wt RET MTC may reveal new therapeutic insights. STUDY DESIGN: We did a retrospective analysis of MTC samples submitted for DNA/RNA sequencing and programmed cell death ligand 1 expression using immunohistochemistry at a Clinical Laboratory Improvement Amendments/College of American Pathologists-certified laboratory. Tumor microenvironment immune cell fractions were estimated using RNA deconvolution (quanTIseq). Transcriptomic signatures of inflammation and MAP kinase pathway activation scores were calculated. Mann-Whitney U, chi-square, and Fisher's exact tests were applied (p values adjusted for multiple comparisons). RESULTS: The 160-patient cohort included 108 mut RET and 52 wt RET MTC samples. wt RET tumors frequently harbored mitogen-activated protein kinase (MAPK) pathway mutations, including HRAS (42.31%), KRAS (15.7%), NF1 (6.7%), and BRAF (2%), whereas only 1 MAPK pathway mutation ( NF1 ) was identified among mut RET MTC. Recurrent mutations seen in wt RET MTC included MGA , VHL, APC , STK11 , and NFE2L2 . Increased transcriptional activation of the MAPK pathway was observed in patients with wt RET harboring mutations in MAPK genes. Although the frequency of programmed cell death ligand 1 expression was similar in wt RET and mut RET (10.2% vs 7%, p = 0.531), wt RET tumors were more often tumor mutational burden high (7.7% vs 0%, p = 0.011), and wt RET MTC exhibited higher expression of immune checkpoint genes. CONCLUSIONS: We identified molecular alterations and immune-related features that distinguish wt RET from mut RET MTC. Although RET mutation drives MTC in the absence of other alterations, we showed that wt RET MTC frequently harbors MAPK pathway mutations. These findings may indicate a potential basis for MAPK-targeted therapy, possibly in combination with immuno-oncology agents for selected patients with wt RET MTC.

Characterization and impact of non-canonical WNT signaling on outcomes of urothelial carcinoma.

BACKGROUND: Non-canonical WNT family (WNT5A pathway) signaling via WNT5A through ROR1 and its partner, ROR2, or Frizzled2 (FZD2) is linked to processes driving tumorigenesis and therapy resistance. We utilized a large dataset of urothelial carcinoma (UC) tumors to characterize non-canonical WNT signaling through WNT5A, ROR1, ROR2, or FZD2 expression. METHODS: NextGen Sequencing of DNA (592 genes or WES)/RNA (WTS) was performed for 4125 UC tumors submitted to Caris Life Sciences. High and low expression of WNT5A, ROR1, ROR2, and FZD2 was defined as ≥ top and

Activating point mutations in the MET kinase domain represent a unique molecular subset of lung cancer and other malignancies targetable with MET inhibitors.

Activating point mutations in the MET tyrosine kinase domain (TKD) are oncogenic in a subset of papillary renal cell carcinomas (PRCC). Here, using comprehensive genomic profiling among >600,000 patients, we identify activating MET TKD point mutations as putative oncogenic driver across diverse cancers, with a frequency of ~0.5%. The most common mutations in the MET TKD defined as oncogenic or likely oncogenic according to OncoKB resulted in amino acid substitutions at positions H1094, L1195, F1200, D1228, Y1230, M1250, and others. Preclinical modeling of these alterations confirmed their oncogenic potential, and also demonstrated differential patterns of sensitivity to type I and type II MET inhibitors. Two patients with metastatic lung adenocarcinoma harboring MET TKD mutations (H1094Y, F1200I) and no other known oncogenic drivers achieved confirmed partial responses to a type I MET inhibitor. Activating MET TKD mutations occur in multiple malignancies and may confer clinical sensitivity to currently available MET inhibitors.

Tissue-specific thresholds of mutation burden associated with anti-PD-1/L1 therapy benefit and prognosis in microsatellite-stable cancers.

Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 or its ligand (PD-1/L1) have expanded the treatment landscape against cancers but are effective in only a subset of patients. Tumor mutation burden (TMB) is postulated to be a generic determinant of ICI-dependent tumor rejection. Here we describe the association between TMB and survival outcomes among microsatellite-stable cancers in a real-world clinicogenomic cohort consisting of 70,698 patients distributed across 27 histologies. TMB was associated with survival benefit or detriment depending on tissue and treatment context, with eight cancer types demonstrating a specific association between TMB and improved outcomes upon treatment with anti-PD-1/L1 therapies. Survival benefits were noted over a broad range of TMB cutoffs across cancer types, and a dose-dependent relationship between TMB and outcomes was observed in a subset of cancers. These results have implications for the use of cancer-agnostic and universal TMB cutoffs to guide the use of anti-PD-1/L1 therapies, and they underline the importance of tissue context in the development of ICI biomarkers.

Molecular Profiling and the Impact of Treatment on Outcomes in Adenoid Cystic Carcinoma Type I and II.

PURPOSE: Adenoid cystic carcinoma (ACC) is an uncommon salivary gland cancer with no approved therapies available to treat advanced, incurable disease. Recent molecular profiling efforts have identified two important subtypes: the more aggressive ACC-I is characterized by Notch pathway alterations and MYC amplification whereas ACC-II demonstrates a more indolent phenotype and TP63 overexpression. EXPERIMENTAL DESIGN: This retrospective observational cohort study involved de-identified samples from 438 patients with ACC with tumor samples sent for commercially-available molecular profiling (Caris Life Sciences). Next-generation whole-exome and whole-transcriptomic sequencing was performed on primary and metastatic samples. Immunostaining for PD-L1 and RNA deconvolution (quanTIseq) was used to explore the tumor immune microenvironment (TME). Real-world clinical and survival outcome metrics were extracted from insurance claims data. RESULTS: MYC expression was 1.61-fold higher (39.8 vs. 24.7; P < 0.0001) among NOTCH1-mutant ACC-I tumors, whereas MYB/L1 fusion rates were similar among ACC-I/II. The median B-cell fraction in the TME was higher among ACC-II (7.1% vs. 5.8%; P < 0.01), although infiltrating T cells subsets were low among either ACC subgroup (both <1%). When pooling systemic treatment categories, ACC-I patients had worse outcomes with available therapies (HR, 3.06; 95% confidence interval, 1.65-5.68; P < 0.01), with no significant difference in overall survival between ACC-I/II based on chemotherapy or VEGFR tyrosine kinase inhibitor exposure in smaller subsets. CONCLUSIONS: We confirmed the previously reported associations with MYC and TP63 in the prognostically relevant subgroups of ACC-I and -II, respectively, and report immunologic differences among these subtypes. Survival outcomes are comparatively worse in ACC-I regardless of treatment type.

ARID2 mutations may relay a distinct subset of cutaneous melanoma patients with different outcomes.

ARID genes encode subunits of SWI/SNF chromatin remodeling complexes and are frequently mutated in human cancers. We investigated the correlation between ARID mutations, molecular features, and clinical outcomes in melanoma patients. Cutaneous melanoma samples (n = 1577) were analyzed by next-generation sequencing. Samples were stratified by pathogenic/likely pathogenic mutation in ARID genes (ARID1A/2/1B/5B). PD-L1 expression was assessed using IHC (SP142; positive (+): ≥ 1%). Tumor mutation burden (TMB)-high was defined as ≥ 10 mutations/Mb. Transcriptomic signatures predictive of response to immune checkpoint inhibitors-interferon gamma and T-cell inflamed score were calculated. Real-world overall survival (OS) information was obtained from insurance claims data, with Kaplan-Meier estimates calculated from time of tissue collection until last date of contact. Mann-Whitney U, Chi-square, and Fisher exact tests were applied where appropriate, with p values adjusted for multiple comparisons. ARID2 mutations were more prevalent in cutaneous melanoma compared to ARID1A (11.0%: n = 451 vs 2.8%: n = 113), with concurrent ARID1A/ARID2 mutation in 1.1% (n = 46) of samples. ARID mutations were associated with a high prevalence of RAS pathway mutations-NF1 (ARID1A, 52.6%; ARID2, 48.5%; ARID1A/2, 63.6%; and ARID-WT, 13.3%; p < 0.0001) and KRAS (ARID1A, 3.5%; ARID2, 3.1%; ARID1A/2, 6.5%; and ARID-WT, 1.0%; p = 0.018)), although BRAF mutations were less common in ARID-mutated cohorts (ARID1A, 31.9%; ARID2, 35.6%; ARID1A/2, 26.1%; and ARID-WT, 50.4%; p < 0.0001). TMB-high was more common in ARID-mutated samples (ARID1A, 80.9%; ARID2, 89.9%; ARID1A/2, 100%; and ARID-WT, 49.4%; p < 0.0001), while PD-L1 positivity was similar across subgroups (ARID1A, 43.8%; ARID2, 51.1%; ARID1A/2, 52.5%; and ARID-WT, 44.9%; p = 0.109). Patients with ARID1A mutations had a higher prevalence of dMMR/MSI-H compared to those with ARID-WT (2.7% vs 0.2%, p = 0.030). Median IFN-γ and T-cell signatures were higher in ARID2-mutated samples compared to ARID-WT (IFN-γ: - 0.15 vs - 0.21, p = 0.0066; T-cell: 23.5 vs - 18.5, p = 0.041). ARID2-mutated patients had improved survival compared to ARID-WT; (HR: 1.22 (95% CI 1.0-1.5), p = 0.022). No additional OS benefit was observed with anti-PD-1 therapy for ARID2 mutation compared to ARID-WT. Melanoma patients with ARID mutations exhibited higher prevalence of markers associated with ICI response, including TMB-H, and immune-related signatures. Our data also suggests improved survival outcome in patients with ARID2 mutations, irrespective of anti-PD1 therapy.

Natural Killer Cell Infiltration in Prostate Cancers Predict Improved Patient Outcomes.

BACKGROUND: Natural killer (NK) cells are non-antigen specific innate immune cells that can be redirected to targets of interest using multiple strategies, although none are currently FDA-approved. We sought to evaluate NK cell infiltration into tumors to develop an improved understanding of which histologies may be most amenable to NK cell-based therapies currently in the developmental pipeline. METHODS: DNA (targeted/whole-exome) and RNA (whole-transcriptome) sequencing was performed from tumors from 45 cancer types (N = 90,916 for all cancers and N = 3365 for prostate cancer) submitted to Caris Life Sciences. NK cell fractions and immune deconvolution were inferred from RNA-seq data using quanTIseq. Real-world overall survival (OS) and treatment status was determined and Kaplan-Meier estimates were calculated. Statistical significance was determined using X2 and Mann-Whitney U tests, with corrections for multiple comparisons where appropriate. RESULTS: In both a pan-tumor and prostate cancer (PCa) -specific setting, we demonstrated that NK cells represent a substantial proportion of the total cellular infiltrate (median range 2-9% for all tumors). Higher NK cell infiltration was associated with improved OS in 28 of 45 cancer types, including (PCa). NK cell infiltration was negatively correlated with common driver mutations and androgen receptor variants (AR-V7) in primary prostate biopsies, while positively correlated with negative immune regulators. Higher levels of NK cell infiltration were associated with patterns consistent with a compensatory anti-inflammatory response. CONCLUSIONS: Using the largest available dataset to date, we demonstrated that NK cells infiltrate a broad range of tumors, including both primary and metastatic PCa. NK cell infiltration is associated with improved PCa patient outcomes. This study demonstrates that NK cells are capable of trafficking to both primary and metastatic PCa and are a viable option for immunotherapy approaches moving forward. Future development of strategies to enhance tumor-infiltrating NK cell-mediated cytolytic activity and activation while limiting inhibitory pathways will be key.

Targeting prostate tumor low-molecular weight tyrosine phosphatase for oxidation-sensitizing therapy.

Protein tyrosine phosphatases (PTPs) play major roles in cancer and are emerging as therapeutic targets. Recent reports suggest low-molecular weight PTP (LMPTP)-encoded by the ACP1 gene-is overexpressed in prostate tumors. We found ACP1 up-regulated in human prostate tumors and ACP1 expression inversely correlated with overall survival. Using CRISPR-Cas9-generated LMPTP knockout C4-2B and MyC-CaP cells, we identified LMPTP as a critical promoter of prostate cancer (PCa) growth and bone metastasis. Through metabolomics, we found that LMPTP promotes PCa cell glutathione synthesis by dephosphorylating glutathione synthetase on inhibitory Tyr270. PCa cells lacking LMPTP showed reduced glutathione, enhanced activation of eukaryotic initiation factor 2-mediated stress response, and enhanced reactive oxygen species after exposure to taxane drugs. LMPTP inhibition slowed primary and bone metastatic prostate tumor growth in mice. These findings reveal a role for LMPTP as a critical promoter of PCa growth and metastasis and validate LMPTP inhibition as a therapeutic strategy for treating PCa through sensitization to oxidative stress.

Development and benchmarking diffusion magnetic resonance imaging analysis for integration into radiation treatment planning.

PURPOSE: The rising promise in the utility of advanced multi-parametric magnetic resonance (MR) imaging in radiotherapy (RT) treatment planning creates a necessity for testing and enhancing the accuracy of quantitative imaging analysis. Standardizing the analysis of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) to generate meaningful and reproducible apparent diffusion coefficient (ADC) and fractional anisotropy (FA) lays the requisite needed for clinical integration. The aim of the demonstrated work is to benchmark the generation of the ADC and FA parametric map analyses using integrated tools in a commercial treatment planning system against the currently used ones. METHODS: Three software packages were used for generating ADC and FA maps in this study; one tool was developed within a commercial treatment planning system, another by the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library FSL (Analysis Group, FMRIB, Oxford, United Kingdom), and an in-house tool developed at the M.D. Anderson Cancer Center. The ADC and FA maps generated by all three packages for 35 subjects were subtracted from one another, and the standard deviation of the images' differences was used to compare the reproducibility. The reproducibility of the ADC maps was compared with the Quantitative Imaging Biomarkers Alliance (QIBA) protocol, while that of the FA maps was compared to data in published literature. RESULTS: Results show that the discrepancies between the ADC maps calculated for each patient using the three different software algorithms are less than 2% which meets the 3.6% recommended QIBA requirement. Except for a small number of isolated points, the majority of differences in FA maps for each patient produced by the three methods did not exceed 0.02 which is 10 times lower than the differences seen in healthy gray and white matter. The results were also compared to the maps generated by existing MR Imaging consoles and showed that the robustness of console generated ADC and FA maps is largely dependent on the correct application of scaling factors, that only if correctly placed; the differences between the three tested methods and the console generated values were within the recommended QIBA guidelines. CONCLUSIONS: Cross-comparison difference maps demonstrated that quantitative reproducibility of ADC and FA metrics generated using our tested commercial treatment planning system were comparable to in-house and established tools as benchmarks. This integrated approach facilitates the clinical utility of diffusion imaging in radiation treatment planning workflow.

Development and Implementation of a Telemental Health Program for Caregivers in a Children's Hospital Setting.

Introduction: Caregivers of children with chronic illness, such as hematology-oncology conditions, face numerous stressors, and a subset experience persistent distress and poor psychological outcomes. Many logistical and ethical barriers complicate the provision of mental health care to caregivers in children's hospital settings. Telemental health (TMH) is one method to increase access and reduce barriers. Methods: A partnership was established with an outside TMH agency to provide mental health care to caregivers of children with hematology-oncology conditions. Development and implementation strategies are described, and feasibility was measured on four dimensions. Results: One hundred twenty-seven (n = 127) caregivers were referred for TMH services in the first 28 months of program implementation. Of the total, 63/127 (49%) received TMH services for at least one session. Most caregivers had a child in active medical treatment (89%). A small portion (11%) of caregivers were bereaved or had a child in hospice care. Program feasibility was enhanced by hospital leadership support and availability of staffing, financial, and technology resources. Available resources also contributed to the practicality of program development and swift implementation and integration within the defined hospital system. Discussion: Partnership with an outside TMH agency increased access to care and reduced barriers to treating caregivers in a children's hospital setting. Offering mental health interventions to caregivers aligns with evidence-based standards of care. Future research will elucidate caregiver satisfaction with this modality of treatment and whether use of TMH reduces disparities in caregiver receipt of mental health care in children's hospital settings.

MIG6 Mediates Adaptive and Acquired Resistance to ALK/ROS1 Fusion Kinase Inhibition through EGFR Bypass Signaling.

Despite the initial benefit from tyrosine kinase inhibitors (TKI) targeting oncogenic ALK and ROS1 gene fusions in non-small cell lung cancer, complete responses are rare and resistance ultimately emerges from residual tumor cells. Although several acquired resistance mechanisms have been reported at the time of disease progression, adaptative resistance mechanisms that contribute to residual diseases before the outgrowth of tumor cells with acquired resistance are less clear. For the patients who have progressed after TKI treatments, but do not demonstrate ALK/ROS1 kinase mutations, there is a lack of biomarkers to guide effective treatments. Herein, we found that phosphorylation of MIG6, encoded by the ERRFI1 gene, was downregulated by ALK/ROS1 inhibitors as were mRNA levels, thus potentiating EGFR activity to support cell survival as an adaptive resistance mechanism. MIG6 downregulation was sustained following chronic exposure to ALK/ROS1 inhibitors to support the establishment of acquired resistance. A higher ratio of EGFR to MIG6 expression was found in ALK TKI-treated and ALK TKI-resistant tumors and correlated with the poor responsiveness to ALK/ROS1 inhibition in patient-derived cell lines. Furthermore, we identified and validated a MIG6 EGFR-binding domain truncation mutation in mediating resistance to ROS1 inhibitors but sensitivity to EGFR inhibitors. A MIG6 deletion was also found in a patient after progressing to ROS1 inhibition. Collectively, this study identifies MIG6 as a novel regulator for EGFR-mediated adaptive and acquired resistance to ALK/ROS1 inhibitors and suggests EGFR to MIG6 ratios and MIG6-damaging alterations as biomarkers to predict responsiveness to ALK/ROS1 and EGFR inhibitors.

Molecular Characterization of TFE3-Rearranged Renal Cell Carcinoma: A Comparative Study With Papillary and Clear Cell Renal Cell Carcinomas.

TFE3-rearranged renal cell carcinoma (rRCC) is a rare subtype of renal cell carcinomas belonging to the MiT family translocation RCC. To further elucidate the co-alterations that occur along with TFE3 fusions in rRCC, we characterized the genomic, transcriptional, and immune landscapes in comparison to clear cell (ccRCC) and papillary renal cell carcinoma (pRCC). Next-generation sequencing of RNA (whole transcriptome) and DNA (592-gene panel or whole exome) for rRCC (N = 20), pRCC (N = 20), and ccRCC samples (N = 392) was performed. Patients with rRCC were significantly younger and more frequently female (median 44.5 years, 75.0% female) as compared with patients with pRCC (68.5 years, 25.0% female; P < .05) and ccRCC (62.0 years, 27.8% female; P < .05). A total of 8 unique fusion partners were observed, including a novel fusion with SRRM2::TFE3 in 2 patients. ccRCC exhibited significantly higher mutation rates of VHL (0% rRCC, 0% pRCC, 78.7% ccRCC; P < .05) and PBMR1 (0% rRCC, 5.0% pRCC, 49.4% ccRCC; P < .05). The genomic landscapes of rRCC were sparse with no mutations occurring with a prevalence higher than 10% other than pTERT (18.2% rRCC, 0% pRCC, 9.2% ccRCC). rRCC were associated with significantly less M1 macrophages (0.8%) as compared with pRCC (1.4%) and ccRCC (2.7%) (P < .05), suggesting a cold tumor-immune microenvironment. However, rRCC were more commonly PD-L1+ (rRCC 50%, pRCC 19.0%, ccRCC 12.2%; P < .05). Gene set enrichment analysis showed that rRCC are enriched in genes related to oxidative phosphorylation when compared with both ccRCC and pRCC. Despite having a colder tumor-immune microenvironment than pRCC and ccRCC, increased PDL1+ rates in rRCC suggest a potential benefit from immune checkpoint inhibitor therapy.

Co-occurring BRCA2/SPOP Mutations Predict Exceptional Poly (ADP-ribose) Polymerase Inhibitor Sensitivity in Metastatic Castration-Resistant Prostate Cancer.

BACKGROUND AND OBJECTIVE: BRCA2 mutations in metastatic castration-resistant prostate cancer (mCRPC) confer sensitivity to poly (ADP-ribose) polymerase (PARP) inhibitors. However, additional factors predicting PARP inhibitor efficacy in mCRPC are needed. Preclinical studies support a relationship between speckle-type POZ protein (SPOP) inactivation and PARP inhibitor sensitivity. We hypothesized that SPOP mutations may predict enhanced PARP inhibitor response in BRCA2-altered mCRPC. METHODS: We conducted a multicenter retrospective study involving 13 sites. We identified 131 patients with BRCA2-altered mCRPC treated with PARP inhibitors, 14 of which also carried concurrent SPOP mutations. The primary efficacy endpoint was prostate-specific antigen (PSA) response rate (≥50% PSA decline). The secondary endpoints were biochemical progression-free survival (PSA-PFS), clinical/radiographic progression-free survival (PFS), and overall survival (OS). These were compared by multivariable Cox proportional hazard models adjusting for age, tumor stage, baseline PSA level, Gleason sum, prior therapies, BRCA2 alteration types, and co-occurring mutations. KEY FINDINGS AND LIMITATIONS: Baseline characteristics were similar between groups. PSA responses were observed in 60% (70/117) of patients with BRCA2mut/SPOPwt disease and in 86% (12/14) of patients with BRCA2mut/SPOPmut disease (p = 0.06). The median time on PARP inhibitor treatment was 24.0 mo (95% confidence interval [CI] 19.2 mo to not reached) in this group versus 8.0 mo (95% CI 6.1-10.9 mo) in patients with BRCA2 mutation alone (p = 0.05). In an unadjusted analysis, patients with BRCA2mut/SPOPmut disease experienced longer PSA-PFS (hazard ratio [HR] 0.33 [95% CI 0.15-0.72], p = 0.005) and clinical/radiographic PFS (HR 0.4 [95% CI 0.18-0.86], p = 0.02), and numerically longer OS (HR 0.4 [95% CI 0.15-1.12], p = 0.08). In a multivariable analysis including histology, Gleason sum, prior taxane, prior androgen receptor pathway inhibitor, stage, PSA, BRCA2 alteration characteristics, and other co-mutations, patients with BRCA2mut/SPOPmut disease experienced longer PSA-PFS (HR 0.16 [95% CI 0.05-0.47], adjusted p = 0.001), clinical/radiographic PFS (HR 0.28 [95% CI 0.1-0.81], adjusted p = 0.019), and OS (HR 0.19 [95% CI 0.05-0.69], adjusted p = 0.012). In a separate cohort of patients not treated with a PARP inhibitor, there was no difference in OS between patients with BRCA2mut/SPOPmut versus BRCA2mut/SPOPwt disease (HR 0.97 [95% CI 0.40-2.4], p = 0.94). In a genomic signature analysis, Catalog of Somatic Mutations in Cancer (COSMIC) SBS3 scores predictive of homologous recombination repair (HRR) defects were higher for BRCA2mut/SPOPmut than for BRCA2mut/SPOPwt disease (p = 0.04). This was a retrospective study, and additional prospective validation cohorts are needed. CONCLUSIONS AND CLINICAL IMPLICATIONS: In this retrospective analysis, PARP inhibitors appeared more effective in patients with BRCA2mut/SPOPmut than in patients with BRCA2mut/SPOPwt mCRPC. This may be related to an increase in HRR defects in coaltered disease. PATIENT SUMMARY: In this study, we demonstrate that co-alteration of both BRCA2 and SPOP predicts superior clinical outcomes to treatment with poly (ADP-ribose) polymerase (PARP) inhibitors than BRCA2 alteration without SPOP mutation.