Hereditary Leiomyomatosis And Renal Cell Cancer Research Articles

A new missense mutation c.1240A>G in fumarate hydratase gene leads to uterine leiomyoma associated hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome in Chinese

ObjectiveThis study presents a detailed analysis of the clinical and genetic characteristics of uterine leiomyoma associated with Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC), combined with exploration of family history, pathology, and management procedures, supported by thorough evidence collection. MethodsBlood samples were collected from the proband, and the pathogenic variant was verified using Sanger sequencing. A comprehensive review of family history, FH deficiency pathology, FH and 2SC immunohistochemistry staining was conducted. Functional evidence was derived from clinical and genetic information, supplemented by a literature collection and mutation was reclassified based on ACMG/AMP guidelines. ResultsThe study successfully identifies a novel missense mutation (c.1240A>G; p.Lys414Glu) in exon 9 of FH, with no prior reports in existing databases. The patient's phenotype and family history, coupled with evidence collected from the literature, contribute to the preliminary determination of the variant as likely pathogenic. We also emphasize that the importance of combining FH-deficient morphology and immunohistochemical staining with 2SC for enhanced sensitivity. ConclusionThis research adds a novel missense mutation to the repertoire of FH gene variants, emphasizing its likely pathogenic nature based on a multidimensional analysis of phenotype, family history, and literature evidence. The findings enhance our understanding of the genetic landscape associated with FH and underscore the importance of thorough characterization for accurate variant classification.

Segregation, immunohistochemical, molecular and functional analyses classify a novel missense variant in fumarate hydratase (FH) as pathogenic.

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant cancer predisposition syndrome characterized by cutaneous leiomyomas, uterine leiomyomas, and aggressive renal cancer. Germline variants in the fumarate hydratase (FH) gene predispose to HLRCC. Identifying germline pathogenic FH variants enables lifetime renal cancer screening and genetic testing for family members. In this report, we present a FH missense variant (c.1039T>C (p.S347P)), initially classified as a variant of uncertain significance. Clinical assessment, histopathological findings, molecular genetic studies, and enzymatic activity studies support the re-classification of the FH c.1039T>C variant to "pathogenic" based on ACMG/AMP criteria. Further insights into pathological recognition of FH-deficient renal cancer are discussed and should be recognized. This study has shown how (a) detailed multi-disciplinary analyses of a single variant can reclassify rare missense variants in FH and (b) careful pathological review of renal cancers is obligatory when HLRCC is suspected.

Rewiring of RNA methylation by the oncometabolite fumarate in renal cell carcinoma.

Metabolic reprogramming is a hallmark of cancer that facilitates changes in many adaptive biological processes. Mutations in the tricarboxylic acid cycle enzyme fumarate hydratase (FH) lead to fumarate accumulation and cause hereditary leiomyomatosis and renal cell cancer(HLRCC). HLRCC is a rare, inherited disease characterized by the development of non-cancerous smooth muscle tumors of the uterus and skin, and an increased risk of an aggressive form of kidney cancer. Fumarate has been shown to inhibit 2-oxoglutarate-dependent dioxygenases (2OGDDs) involved in the hydroxylation of HIF1α, as well as in DNA and histone demethylation. However, the link between fumarate accumulation and changes in RNA post-transcriptional modifications has not been defined. Here, we determine the consequences of fumarate accumulation on the activity of different members of the 2OGDD family targeting RNA modifications. By evaluating multiple RNA modifications in patient-derived HLRCC cell lines, we show that mutation of FH selectively affects the levels of N6-methyladenosine (m6A), while the levels of 5-formylcytosine (f5C) in mitochondrial tRNA are unaffected. This supports the hypothesis of a differential impact of fumarate accumulation on distinct RNA demethylases. The observation that metabolites modulate specific subsets of RNA-modifying enzymes offers new insights into the intersection between metabolism and the epitranscriptome.

Hereditary leiomyomatosis and renal cell cancer syndrome

Introduction: Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) is a rare autosomal dominantly inherited cancer predisposing syndrome giving rise to cutaneous and uterine leiomyomatosis, leiomyosarcoma and renal cell cancer. Patients with this syndrome harbours germline pathogenic variants in the fumarate hydratase (FH) gene.Case presentation: A 28-year-old Sri Lankan female, a product of a consanguineous marriage with strong family history of young onset fibroids presented with progressive dysmenorrhea, menorrhagia and irregular menstrual cycles for 2 years duration. There was recent onset lower abdominal colicky pain lasting for 3-5 min occurring during the post coital and intermenstrual period over 2 months. Examination did not reveal abnormal skin lesions or abdominal masses.Ultrasound examination revealed enlarged uterus with 2 large fibroids in the posterior wall and fundus of the uterus. She underwent laparoscopic myomectomy without perioperative complications. Histology revealed a leiomyoma with morphological features supporting the variant “fumarate hydratase deficient leiomyoma”.Whole exome sequencing of the patient revealed her to be harbouring a pathogenic variant c.878T>G| p:Val293Gly in the FH gene for which she was heterozygous confirming that she had inherited the cancer predisposing syndrome of hereditary leiomyomatosis and renal cell cancer(HLRCC). Postoperatively her symptoms resolved, and she was able to sustain an uncomplicated pregnancy one year after. Currently she is closely followed up for future development of tumors including renal cell cancer bothclinically and via imaging.Conclusion: HLRCC is a rare autosomal dominantly inherited cancer syndrome predisposing to skin, uterine and renal tumors warranting surveillance at a younger age.

Hereditary predisposition to kidney cancer: cancer syndromes, multisystemic disorders, and nephropathies

Kidney cancer (KC) is a common disease characterized by extreme heterogeneity. There are nine known monogenic diseases associated with a significantly elevated KC risk: von Hippel-Lindau disease, MET-associated papillary renal cancer, familial multiple leiomyomatosis and renal cell cancer, SDHx-associated familial pheochromocytoma/ paraganglioma, Birt-Hogg-Dube syndrome, tuberous sclerosis, Cowden syndrome, BAP1- and MITF-associated melanoma-KC predisposition. These syndromes differ in the degree of cancer risk, the quantity, growth and progression rates of associated precancerous lesions, the morphology, and clinical presentations of malignancy itself, and in the response to therapy. Identification of causative germline lesion allows planning the surveillance of a mutation carrier, choosing the right time and extent of surgery, and optimizing treatment regimen. Hereditary KC research often brings forward novel approaches to the management of sporadic “phenocopies” of hereditary syndromes, i.e. sporadic cancers with somatic mutations in similar genes. The main directions for further study of genetic factors of KC are to find novel KC genes, to study risk modifiers in carriers of highly penetrant mutations, to clarify the involvement of hereditary nephropathies in the occurrence of renal cancers.

Cryptic splice mutation in the fumarate hydratase gene in patients with clinical manifestations of hereditary Leiomyomatosis and renal cell cancer (HLRCC).

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an autosomal dominant condition characterized by the development of cutaneous and uterine leiomyomas and risk for development of an aggressive form of papillary renal cell cancer. HLRCC is caused by germline inactivating pathogenic variants in the fumarate hydratase (FH) gene, which encodes the enzyme that catalyzes the interconversion of fumarate and L-malate. We utilized enzyme and protein mobility assays to evaluate the FH enzyme in a cohort of patients who showed clinical manifestations of HLRCC but were negative for known pathogenic FH gene variants. FH enzyme activity and protein levels were decreased by 50% or greater in three family members, despite normal FH mRNA expression levels as measured by qPCR. Direct Nanopore RNA sequencing demonstrated 57 base pairs of retained intron sequence between exons 9 and 10 of polyadenylated FH mRNA in these patients, resulting in a truncated FH protein. Genomic sequencing revealed a heterozygous intronic alteration of the FH gene (chr1: 241498239T/C) resulting in formation of a splice acceptor site near a polypyrimidine tract, and a uterine fibroid obtained from a patient showed loss of heterozygosity at this site. The same intronic FH variant was identified in an unrelated patient who also showed a clinical phenotype of HLRCC. These data demonstrate that careful clinical assessment as well as biochemical characterization of FH enzyme activity, protein expression, direct RNA sequencing and genomic DNA sequencing of patient-derived cells can identify pathogenic variants outside of the protein coding regions of the FH gene.

Fumarase Deficiency and Its Effect on Infertility: A Case Series.

Fumarase deficiency is an autosomal recessive condition characterized by severe neurologic abnormalities due to homozygous mutations in the fumarate hydratase (FH) gene. Heterozygous carriers of FH mutations have increased risk of developing uterine fibroids that can be associated with hereditary leiomyomatosis and renal cell cancer (HLRCC). The association between FH mutations and infertility remains uncertain. The objective of our study was to characterize the infertility diagnoses, treatments, and outcomes in women presenting to a fertility center who were found to be carriers of fumarase deficiency based on the presence of heterozygous FH mutations. A retrospective case series was conducted including 10 women presenting to an academic fertility center who were found to be FH carriers based on genetic carrier screening. Of the 9 women who were engaged in further workup, 2 had imaging results consistent with uterine fibroids. One woman underwent hysteroscopic myomectomy prior to two courses of ovulation induction with timed intercourse (OI/TIC) followed by one successful cycle of IVF. Of the remaining patients, only 1 woman successfully delivered after a cycle of ovulation induction with intrauterine insemination (OI/IUI). Other patients pursuing OI/IUI, OI/TIC, or monitored natural cycles had unsuccessful experiences. Patients with infertility who are offered genetic testing should be screened for FH mutations, as the carriers are at risk of developing HLRCC-associated uterine fibroids, which can influence fertility and pregnancy. Additional research is needed to investigate the impacts of FH mutations on infertility.

FOXA2 controls the anti-oxidant response in FH-deficient cells

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a cancer syndrome caused by inactivating germline mutations in fumarate hydratase (FH) and subsequent accumulation of fumarate. Fumarate accumulation leads to profound epigenetic changes and the activation of an anti-oxidant response via nuclear translocation of the transcription factor NRF2. The extent to which chromatin remodeling shapes this anti-oxidant response is currently unknown. Here, we explored the effects of FH loss on the chromatin landscape to identify transcription factor networks involved in the remodeled chromatin landscape of FH-deficient cells. We identify FOXA2 as a key transcription factor that regulates anti-oxidant response genes and subsequent metabolic rewiring cooperating without direct interaction with the anti-oxidant regulator NRF2. The identification of FOXA2 as an anti-oxidant regulator provides additional insights into the molecular mechanisms behind cell responses to fumarate accumulation and potentially provides further avenues for therapeutic intervention for HLRCC.

EDITORIAL COMMENT

Paragangliomas and pheochromocytomas (PGL/PCC) are rare tumors that are derived from neural crest chromaffin cells either from neuroendocrine tissues distributed along the spine or from within the adrenal gland respectively. Approximately 40% of cases are associated with pathogenic germline variants in genes associated to cancer susceptibility syndromes, such as MAX, NF1, RET, SDHA, and SDHAF2, including several gene that associated with inherited kidney cancer, such as VHL, SDHB, SDHC, SDHD, and TMEM127. 1 Shuch B Ricketts CJ Metwalli AR Pacak K Linehan WM. The genetic basis of pheochromocytoma and paraganglioma: implications for management. Urology. 2014; 83: 1225-1232 Google Scholar ,2 Dahia PL. Pheochromocytoma and paraganglioma pathogenesis: learning from genetic heterogeneity. Nat Rev Cancer. 2014; 14: 108-119 Google Scholar A recent addition to this list is germline alteration of the FH gene, known to cause hereditary leiomyomatosis and renal cell cancer (HLRCC). 3 Richter S Gieldon L Pang Y et al. Metabolome-guided genomics to identify pathogenic variants in isocitrate dehydrogenase, fumarate hydratase, and succinate dehydrogenase genes in pheochromocytoma and paraganglioma. Genet Med. 2019; 21: 705-717 Google Scholar , 4 Clark GR Sciacovelli M Gaude E et al. Germline FH mutations presenting with pheochromocytoma. J Clin Endocrinol Metab. 2014; 99: E2046-E2050 Google Scholar , 5 Muller M Ferlicot S Guillaud-Bataille M et al. Reassessing the clinical spectrum associated with hereditary leiomyomatosis and renal cell carcinoma syndrome in French FH mutation carriers. Clin Genet. 2017; 92: 606-615 Google Scholar

A Missense Mutation c.1132G > A in Fumarate Hydratase (FH) Leads to Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC) Syndrome and Insights into Clinical Management in Uterine Leiomyomata

HLRCC syndrome is a hereditary cancer predisposition syndrome caused by heterozygous germline pathogenic variant of the fumarate hydratase (FH) gene and characterized by cutaneous leiomyomas (CL), uterine leiomyomas (UL), and renal cell carcinoma (RCC). Loss of function variant of FH gene inactivates the Kreb's cycle enzyme activity and predisposes individuals with such variant to the development of HLRCC. Next-generation sequencing (NGS) and Sanger confirmation were given to family members accessible. Following that, a functional study in vitro was performed to further confirm the pathogenicity of the variant. FH-Wild type (FH-WT) and FH-mutant (FH-MUT) (E378K) plasmid were constructed and transfected into 293T and uterine leiomyoma cell lines, respectively. Proliferation assessment was executed to show how this mutation affects the growth of uterine leiomyoma. qPCR and Western blotting were performed to investigate the change of transcription and translation of FH with mutation (E378K), and FH enzyme assay activity were tested in 293T cells with mutation and wild-type plasmids. Here, we presented two families with the same missense variant (c.1132G > A) that has not been reported as a germline mutation in hereditary uterine leiomyomas before and classified as VUS in gene databases. Our in vitro experiments supported the pathogenicity of this missense variant, especially in uterine leiomyomata. According to the American College of Medical Genetics (ACMG) guideline, the E378K variant was classified as likely pathogenic (with evidence PS4_support, PS3_support, PM2_support, PP1, PP3 and PP4 evidence). Further insights into clinical management in uterine leiomyomata were discussed and should be practiced in gynecological clinical settings.

Fumarate Hydratase Variants and Their Association With Paraganglioma/Pheochromocytoma

ObjectiveTo clarify the link between germline variants in fumarate hydratase (FH), hereditary leiomyomatosis and renal cell cancer (HLRCC), and paraganglioma (PGL) and pheochromocytoma (PCC) we utilize a well-annotated hereditary cancer testing database. MethodsRecords of 120,061 patients receiving germline testing were obtained. FH variants were classified into 4 categories: autosomal dominant (AD) HLRCC variants, autosomal recessive (AR) fumarase deficiency (FMRD), variants, previously reported as PGL/PCC FH variants, and variants of unknown significance (VUS) not previously associated with PGL/PCC (NPP-VUS). Rates of PGL/PCC were compared with those with negative genetic testing. ResultsAbout 1.3% of individuals carried FH variants which were more common among individuals with PGL/PCC compared to those without (3.1% vs 1.3%, P < .0001). PGL/PCC rates were higher among individuals with PGL/PCC FH variants compared to those with negative genetic testing (22.2% vs 0.9%, P < .0001). Neither AD HLRCC variants (0.3% vs 0.9%, P = .35) nor AR FMRD variants (1.4% vs 0.9%, P = .19) carried an increased prevalence of PGL/PCC. An increased prevalence of PGL/PCC was detected in those with NPP-VUS (2.0% vs 0.9%, P = .0023). ConclusionsCertain FH variants confer an increased risk of PGL/PCC, but not necessarily HLRCC. While universal screening for PGL/PCC among all individuals with FH variants does not appear warranted, it should be considered in select high-risk PGL/PCC FH variants.

33327 A case of reed syndrome with an unusually extensive cutaneous burden

Reed Syndrome, or hereditary leiomyomatosis and renal cell carcinoma syndrome, is a rare, autosomal dominant genetic condition that predisposes individuals to a triad of cutaneous leiomyomas (CLMs), uterine leiomyomas and renal cell carcinoma. CLMs are often the first manifestation of the syndrome, occurring in 76% of patients typically in their second to fourth decade of life. CLMs are smooth-surfaced, reddish-brown papules or nodules that range 0.2 to 2.0 cm in diameter and average 25 in number. We present a case of a 47-year-old female with Reed syndrome with an unusually extensive cutaneous burden, with a total of 361 cutaneous lesions, far above the average reported number of 25. Due to the extent of her cutaneous burden, painful nature of the lesions and failure to respond to standard therapies, she was referred for fully ablative erbium laser resurfacing therapy. The use of fully ablative erbium laser resurfacing therapy for treatment of CLMs has not been reported in the literature to date. One year following laser therapy, the treatment area not only healed with normal repigmentation, but there was also no evidence of CLMs recurrence. Given the effectiveness of this unique therapy, fully ablative erbium laser resurfacing should be kept in mind as a treatment option for both cosmetic and symptomatic CLMs.

Hereditary leiomyomatosis and renal cell cancer: a case report

This article presents a case report of hereditary leiomyomatosis and renal cell cancer (HLRCC) with new mutation in a 25-year-old female patient admitted to the clinic for diagnosis and treatment due to multiple skin and uterus leiomyomas. The patient has a history of surgery to remove adrenal pheochromocytoma and papillary kidney cancer. Clinical and laboratory examination as well as medical genetic counseling of the patient were performed. We have detected the heterozygous c.395_399del (p.L132*) germline nonsense mutation in exon 4 of the FH gene using polymerase chain reaction/Sanger sequencing of exons 1–10 of this gene and confirmed the diagnosis of HLRCC. The mutation c.395_399del in a patient with HLRCC was described for the first time. The identical mutation was also found in the mother and sister of the patient. Based on the obtained results, medical genetic counseling was carried out in this family, recommendations were given for further oncological monitoring. The case report could be useful for geneticists, oncologists and other specialists to interpretate the clinical heterogeneity of HLRCC and improve the genetic diagnosis of this rare hereditary oncological syndrome.

A phase 2 study of bevacizumab, erlotinib, and atezolizumab in subjects with advanced hereditary leiomyomatosis and renal cell cancer (HLRCC) associated or sporadic papillary renal cell cancer (pRCC).

TPS4604 Background: Papillary RCC accounts for 10-15% of kidney cancers and is the second most common subtype of RCC after clear cell RCC. HLRCC is a familial cancer syndrome characterized by a propensity for developing papillary kidney cancer. HLRCC-associated renal tumors are known to be clinically aggressive, with a paucity of treatment options. The combination of bevacizumab and erlotinib has shown promising activity in patients with HLRCC-associated RCC and sporadic pRCC (Srinivasan et al, ASCO 2020). We hypothesize that the addition of a PDL-1 inhibitor might provide synergistic clinical activity against these tumors. Methods: This is an ETCTN-sponsored, open-label, multicenter, phase 2 study evaluating bevacizumab, erlotinib and atezolizumab in adult and pediatric patients with advanced 1) HLRCC-associated RCC or 2) sporadic pRCC. Eligible patients will have cytologically or histologically confirmed advanced HLRCC- associated or sporadic pRCC, age ≥12 years, ECOG PS ≤2, no more than two prior regimens targeting the VEGF pathway, no prior treatment with PD-1 or PD-L1 inhibitors and adequate organ and marrow function. Patients with HLRCC-associated RCC or sporadic pRCC will be enrolled into parallel, independent cohorts. Initially, 12 adult patients with advanced HLRCC-associated RCC or sporadic pRCC will be enrolled into the safety run-in portion of the trial. If ≤ 3 dose-limiting toxicities are observed, enrollment will proceed into both cohorts and pediatric patients will be allowed to enroll. A Simon two-stage phase 2 minimax design will be used to determine accrual to each cohort. In the first stage, 12 evaluable patients will be enrolled into cohort 1) HLRCC-associated RCC or cohort 2) sporadic pRCC. If 0 of 12 patients have a CR, then no further patients will be enrolled in that cohort. If 1 or more of the first 12 evaluable patients enrolled have a clinical response, then accrual will continue until a total of 21 evaluable patients (adult or pediatric) have been enrolled into each cohort for a total of 42 patients. Adult patients will receive a fixed dose of bevacizumab (15 mg/kg IV every 21 days) plus atezolizumab (1,200 mg IV every 21 days) and erlotinib (150 mg PO daily). Pediatric patients will receive bevacizumab (15 mg/kg IV every 21 days) plus atezolizumab 15 mg/kg (max 1,200 mg IV every 21 days) and erlotinib 85 mg/m2 (max 150 mg PO daily). The primary endpoint is to assess the complete response rate according to RECIST 1.1 in patients with advanced 1) HLRCC-associated RCC and 2) sporadic pRCC. Secondary endpoints include safety and tolerability, objective response rate, disease control rate, progression-free survival and overall survival. Key exploratory endpoints include evaluation of immunologic modulation associated with this regimen. The study has just opened to accrual. Clinical trial information: NCT04981509.

Cyst(e)inase–Rapamycin Combination Induces Ferroptosis in Both In Vitro and In Vivo Models of Hereditary Leiomyomatosis and Renal Cell Cancer

Renal cell carcinomas associated with hereditary leiomyomatosis and renal cell cancer (HLRCC) are notoriously aggressive and represent the leading cause of death among patients with HLRCC. To date, a safe and effective standardized therapy for this tumor type is lacking. Here we show that the engineered synthetic therapeutic enzyme, Cyst(e)inase, when combined with rapamycin, can effectively induce ferroptosis in HLRCC cells in vivo. The drug combination promotes lipid peroxidation to a greater degree than cysteine deprivation or Cyst(e)inase treatment alone, while rapamycin treatment alone does not induce ferroptosis. Mechanistically, Cyst(e)inase induces ferroptosis by depleting the exogenous cysteine/cystine supply, while rapamycin reduces cellular ferritin level by promoting ferritins' destruction via ferritinophagy. Since both Cyst(e)inase and rapamycin are well tolerated clinically, the combination represents an opportunity to exploit ferroptosis induction as a cancer management strategy. Accordingly, using a xenograft mouse model, we showed that the combination treatment resulted in tumor growth suppression without any notable side effects. In contrast, both Cyst(e)inase only and rapamycin only treatment groups failed to induce a significant change when compared with the vehicle control group. Our results demonstrated the effectiveness of Cyst(e)inase-rapamycin combination in inducing ferroptotic cell death in vivo, supporting the potential translation of the combination therapy into clinical HLRCC management.

Molecular and immune landscape of FH-mutated kidney cancer.

382 Background: Hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome is caused by inactivating germline mutations in fumarate hydratase ( FH), predisposing individuals to development of certain cancers. Sporadic FH mutations have been described in different types of cancers, including kidney cancers, but the implications of somatic mutations are not well described. Here, we characterize the molecular landscape of kidney tumors with FH mutations. Methods: Tumors were analyzed using next generation sequencing of DNA (NextSeq, 592 genes and NovaSeq, WES) and RNA (NovaSeq). Immune cell fraction was estimated by immune deconvolution (Quantiseq). Significance was determined by chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons (q-value &lt;0.05). Results: Of 1956 kidney tumors, 31 had somatic pathogenic or likely pathogenic (P+LP; 1.58%) and 21 had variant of unknown significance (VUS; 1.07%) mutations in FH. Among the most commonly co-mutated genes, VHL (29.03% vs 38.1% vs 55.2%) and PBRM1 (9.68% vs 20% vs 29.8%) were less frequently mutated in P+LP compared to VUS and WT tumors; while NF2 (22.6% vs 5% vs 5.65%) was more frequently mutated in P+LP tumors compared to the others. In P+LP tumors, the HIPPO pathway (22.6% vs 4.76% vs 5.62%) was more frequently altered while the chromatin remodeling pathway (25.8% vs 28.6% vs 51.1%) was less frequently altered compared to VUS or WT tumors. P+LP tumors showed decreased NK cell infiltration (q=0.01) compared to VUS and WT tumors. Additionally, there was a trend towards increased CD8+ T cells and CTLA4 and PDCD1 expression in P+LP tumors compared to VUS but not WT tumors. Of the 1,956 kidney tumors, 315 were of clear cell renal cell carcinoma (ccRCC) histology. P+LP (n=4) ccRCC tumors showed a trend towards higher expression of immune checkpoint genes CTLA4 and IDO1 compared to VUS tumors (n=5). VHL expression was higher in P+LP ccRCC compared to VUS ccRCC tumors. P+LP ccRCC tumors showed a trend toward increased CD4+ (2.59% vs 0%) and CD8+ (2.14% vs 0%) T cells as well as T cell inflammation (25% vs 0%) and median Interferon score compared to VUS ccRCC tumors. Conclusions: P+LP FH mutated kidney tumors may have a different mutational and immune landscape than VUS FH mutated and WT tumors. Despite the small sample size, our study highlights potential therapeutic implications that will require further study.[Table: see text]

Stromal luteoma in a case of multiple leiomyomatosis – A rare case report

Stromal luteoma of the ovary occurs mostly in postmenopausal females and is very rare. They account for 60% Abnormal vaginal bleeding is the most frequent presentation, but endocrine symptoms and sometimes virilizing signs may also be observed. This tumour is a close mimicker of Leydig cell tumour. However, the stromal location and the absence of Reinke’s crystalloids helps to confirm the diagnosis. This tumour is surrounded by an ovarian stroma, entirely composed of luteinized cells devoid of crystals of Reinke. We report an unusual case of a 41 year old female who presented with abdominal pain and menorrhagia. A TAH + BSO was performed and microscopy revealed a stromal luteoma of the right ovary with multiple intramural and subserosal fibroids. Preoperative diagnosis was a leiomyoma. However, microscopy revealed a stromal luteoma in the ovary. One third of the stromal luteomas are incidental findings. The preoperative and intraoperative diagnosis of this condition is challenging. Awareness about this condition among pathologists and clinicians may help in preventing misdiagnosis and overtreatment.

Abstract P055: Targeting Krebs-cycle-deficient renal cell carcinoma with PARP inhibitor and low-dose alkylating chemotherapy

Abstract Loss-of-function mutations in genes encoding the Krebs cycle enzymes fumarate hydratase (FH) and succinate dehydrogenase (SDH) lead to excess accumulation of fumarate and succinate, respectively. Germline mutations in FH lead to a genetic predisposition to hereditary leiomyomatosis and renal cell cancer (HLRCC)-associated RCC. Similarly, loss-of-function alterations of SDH, most commonly SDHB, are associated with SDH-deficient neoplasms, including RCC. FH and SDHB deficient RCC tends to be aggressive and metastasize early with very limited treatment options. The oncometablites produced by these mutations, fumarate and succinate, competitively inhibit αKG-dependent dioxygenases, resulting in dysregulated DNA methylation and histone modification. We have previously demonstrated that elevated levels of fumarate and succinate both suppress the homologous recombination (HR) DNA-repair pathway through inhibition of the lysine demethylase KDM4B, resulting in aberrant hypermethylation of histone 3 lysine 9 (H3K9) at loci surrounding DNA breaks and masking a local H3K9 trimethylation signal that is essential for the proper execution of HR. In this study, we sought to identify novel treatment approaches that exploit genomic instability in FH- and SDHB-deficient RCC. Temozolomide (TMZ), an alkylating agent, mediates its cytotoxic effect by attaching methyl groups to DNA (O6-guanine, N7-guanine and N3-adenine). 16 N3-MetA and N7-MetG repair are mediated by the base excision repair (BER) in a process involving PARP. While the combination of PARP inhibitors with TMZ has been shown to increase TMZ-induced cytotoxicity, clinical trials investigating combination therapy have been hampered by significant toxicity. Using CRISPR/Cas9, we developed new syngeneic FH- and SDHB-deficient murine models of RCC. We demonstrate that FH- and SDHB-deficient cells have accumulation of fumarate and succinate leading to an increase in unresolved DNA double-strand breaks (DSBs). Treatment with PARP inhibition and temozolomide results in marked in vitro cytotoxicity in FH- and SDHB-deficient cells, even at low concentrations of TMZ (50 µM). In vivo, the combination of standard dose BGB-290 and low-dose TMZ (3mg/kg/dose) results in significantly delayed tumor progression in an SDHB deficient RENCA model without any significant increase in toxicity. Notably, the TMZ dose of 3mg/kg/dose is significantly lower than the 50mg/kg/dose that is commonly used for in vivo studies. Taken together, these findings provide the basis for a novel therapeutic strategy exploiting HR deficiency in FH and SDHB-deficient RCC with combined PARP inhibition and low-dose alkylating chemotherapy. Furthermore, the development of a new syngeneic mouse model provides a tool for the future study of immunotherapy in Krebs-cycle-deficient RCC. Citation Format: Daiki Ueno, Amrita Sule, Jiayu Liang, Jinny van Doorn, Ranjini Sundaram, Randy Caliliw, Huihui Ye, Rong Rong Huang, Jing Li, Karla Boyd, Ranjit S. Bindra, Juan C. Vasquez, Brian M. Shuch. Targeting Krebs-cycle-deficient renal cell carcinoma with PARP inhibitor and low-dose alkylating chemotherapy [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P055.

Reed Syndrome in Eighteen Patients: A Genodermatosis Where Piloleiomyomas May Be the Diagnostic Clue

Introduction: Hereditary leiomyomatosis and renal cell cancer (HLRCC) is caused by germline heterozygous mutations of the fumarate hydratase (FH) gene. Materials and Methods: A retrospective observational study was conducted, aimed at characterizing the clinical features, histopathology, and genetic mutations in eighteen patients with confirmed HLRCC diagnosis. Results: FH gene mutations were identified in the seven families studied, including a previously undescribed mutation. All index cases of the families included were suspected on skin manifestations. Thirteen of the 18 patients (72%) presented cutaneous leiomyomas. The chief complaint was pain, with complete but transient response to botulinum toxin in one. No evidence of malignant transformation was observed. Uterine leiomyomas were present in seven of the eight women studied (88%). There was no evidence of renal cell carcinoma in any of the patients in the study. The most frequently found mutations were missense type (43%), followed by large rearrangements (24%), intronic deletions (14%) and nonsense (14%). A novel mutation not previously described in the literature is presented. Conclusions: HLRCC is a rare disease but it is also probably underdiagnosed. Dermatologists have an essential role in its diagnosis, by recognizing the clinical characteristics of the syndrome and investigating the family history.

Fumarate hydratase variant prevalence and manifestations among individuals receiving germline testing

Germline variants in fumarate hydratase (FH) are associated with autosomal dominant (AD) hereditary leiomyomatosis and renal cell cancer (HLRCC) and autosomal recessive (AR) fumarase deficiency (FMRD). The prevalence and cancer penetrance across different FH variants remain unclear. A database containing 120,061 records from individuals undergoing cancer germline testing was obtained. FH variants were classified into 3 categories: AD HLRCC variants, AR FMRD variants, and variants of unknown significance (VUSs). Individuals with variants from these categories were compared with those with negative genetic testing. FH variants were detected in 1.3% of individuals (AD HLRCC, 0.3%; AR FMRD, 0.4%; VUS, 0.6%). The rate of AD HLRCC variants discovered among reportedly asymptomatic individuals without a clear indication for HLRCC testing was 1 in 2668 (0.04%). In comparison with those with negative genetic testing, the renal cell carcinoma (RCC) prevalence was elevated with AD HLRCC variants (17.0% vs 4.5%; P<.01) and VUSs (6.4% vs 4.5%; P=.02) but not with AR FMRD variants. The prevalence of HLRCC discovered incidentally on germline testing is similar to recent population carrier estimates, and this suggests that this is a relatively common cancer syndrome. Compared with those with negative genetic testing, those with VUSs had an elevated risk of RCC, whereas those with AR FMRD variants did not.