Inactivating mutations in tumor suppressor genes TP53 and RB1 are considered central drivers in leiomyosarcomas (LMSs). In high-risk human papillomavirus (HPV)-related tumors, a similar functional outcome is achieved through oncoproteins E6 and E7, which inactivate the p53 and RB1 proteins, respectively. Here, we hypothesized that HPV infection could provide an alternative mechanism for tumorigenesis in a subset of TP53/RB1-wildtype LMS. We evaluated tumor samples from 2585 consecutive unique patients carrying a diagnosis of gynecologic or soft tissue LMS. Tumor DNA and available RNA were analyzed by hybrid-capture-based next-generation sequencing/comprehensive genomic profiling of 406 genes and transcripts (FoundationOneHeme). Of the initial 2585 cases, we excluded 16 based on the presence of molecular alterations that are considered defining for sarcomas other than LMS. In the remaining 2569 cases, we searched for LMS that were TP53/RB1-wildtype (n=486 of 2569; 18.9%). We also searched LMS tumors for HPV sequences that we then classified into genotypes by de novo assembly of nonhuman sequencing reads followed by alignment to the RefSeq database. Among TP53/RB1-wildtype LMS, we identified 18 unique cases harboring HPV sequences. Surprisingly, most (n=11) were HPV51-positive, and these 11 represented all HPV51-positive tumors in our entire LMS database (n=11 of 2569; 0.4%). The absence of genomic alterations in TP53 or RB1 in HPV51-positive LMS represented a marked difference from HPV51-negative LMS (n=2558; 0% vs. 72% [P<0.00001], 0% vs. 53% [P=0.0002]). In addition, compared with HPV51-negative LMS, HPV51-positive LMS were significantly enriched for genomic alterations in ATRX (55% vs. 24%, P=0.027) and TSC1 (18% vs. 0.6%, P=0.0047). All HPV51-positive LMS were in women; median age was 54 years at surgery (range: 23 to 74 y). All known primary sites were from the gynecologic tract or adjacent anogenital area, including 5 cases of vaginal primary site. Histology was heterogeneous, with evaluable cases showing predominant epithelioid (n=5) and spindle (n=5) morphology. In situ hybridization confirmed the presence of high-risk HPV E6/E7 mRNA in tumor cells in three of three evaluable cases harboring HPV51 genomic sequences. Overall, in our pan-LMS analysis, HPV reads were identified in a subset of TP53/RB1-wildtype LMS. For all HPV51-associated LMS, the striking absence of any detectable TP53 or RB1 mutations and predilection for the female lower reproductive tract supports our hypothesis that high-risk HPV can be an alternative tumorigenic mechanism in this distinct class of LMS.

肿瘤抑制基因TP53和RB1的失活突变被认为是平滑肌肉瘤 (LMS) 的核心驱动因素。在高危人乳头瘤病毒 (HPV) 相关肿瘤中，通过癌蛋白 E6 和 E7 实现了类似的功能结果，它们分别使 p53 和 RB1 蛋白失活。在这里，我们假设 HPV 感染可以为TP53/RB1野生型 LMS的子集的肿瘤发生提供替代机制。我们评估了来自 2585 名连续诊断为妇科或软组织 LMS 的独特患者的肿瘤样本。通过基于杂交捕获的下一代测序/406 个基因和转录本的综合基因组分析 (FoundationOneHeme) 来分析肿瘤 DNA 和可用 RNA。在最初的 2585 例病例中，我们根据分子改变的存在排除了 16 例，这些改变被认为是 LMS 以外的肉瘤的定义。在其余 2569 个病例中，我们搜索了TP53/RB1野生型的 LMS（n=2569 例中的 486 例；18.9%）。我们还搜索了 LMS 肿瘤中的 HPV 序列，然后通过非人类测序读数的从头组装，然后与 RefSeq 数据库进行比对，将其分类为基因型。在TP53/RB1野生型 LMS 中，我们鉴定了 18 个携带 HPV 序列的独特病例。令人惊讶的是，大多数 (n=11) 为 HPV51 阳性，这 11 个代表了我们整个 LMS 数据库中的所有 HPV51 阳性肿瘤（2569 例中，n=11；0.4%）。HPV51 阳性 LMS 中TP53或RB1不存在基因组改变，与 HPV51 阴性 LMS 存在显着差异（n=2558；0% vs. 72% [ P <0.00001]、0% vs. 53% [ P =0.0002] ]）。此外，与HPV51阴性LMS相比，HPV51阳性LMS在ATRX（55% vs. 24%，P =0.027）和TSC1（18% vs. 0.6%，P =0.0047）中的基因组改变显着富集。所有 HPV51 阳性 LMS 均为女性；手术时中位年龄为 54 岁（范围：23 至 74 岁）。所有已知的原发部位均来自妇科或邻近的肛门生殖器区域，其中5例为阴道原发部位。组织学呈异质性，可评估病例显示主要为上皮样（n=5）和纺锤体（n=5）形态。原位杂交证实，在含有 HPV51 基因组序列的三个可评估病例中，有 3 个病例的肿瘤细胞中存在高危 HPV E6/E7 mRNA。总体而言，在我们的泛 LMS 分析中，在TP53/RB1野生型 LMS 的子集中鉴定了 HPV 读数。对于所有 HPV51 相关的 LMS，明显缺乏任何可检测到的TP53或RB1女性下生殖道的突变和偏好支持了我们的假设，即高危 HPV 可能是这种独特类型的 LMS 的另一种致瘤机制。