High frequency of activating PIK3CA mutations in human papillomavirus-positive oropharyngeal cancer.

IMPORTANCE: Large-scale whole-exome sequencing studies of head and neck squamous cell carcinoma (HNSCC) have established that the disease is dominated by frequent mutations in tumor suppressor genes with rare activating mutations in oncogenes that would be easily targetable with molecular agents. There was evidence in these reports, however, that activating mutations in phosphoinositide 3-kinase catalytic subunit p110α (PIK3CA) were common in patients with human papillomavirus (HPV)-positive tumors. We set out to test this prediction in oropharyngeal patient samples from our institution. OBJECTIVE: To confirm whether activating mutations in PIK3CA are frequent in HPV-positive HNSCC because this mutated oncogene represents a potential therapeutic target. DESIGN, SETTING, AND PARTICIPANTS: A retrospective search of the London Health Sciences Centre pathology database was performed to identify oropharyngeal cancer samples. DNA from pretreatment primary site biopsy samples from 87 patients were tested for high-risk HPV types 16 and 18 by real-time polymerase chain reaction. MAIN OUTCOMES AND MEASURES: Samples were tested for activating mutations at the 3 mutational hot spots (codons 542, 545, and 1047) by polymerase chain reaction followed by Sanger sequencing using forward and reverse primers. RESULTS: Only 4 of 41 HPV-negative tumors (10%) demonstrated PIK3CA hot spot mutations, including 3 at codon 1047 and 1 at codon 542. Of 46 HPV-positive tumors, 13 (28%) demonstrated activating PIK3CA mutations, including 7 at codon 542, 5 at codon 545, and 1 at codon 1047. The difference in PIK3CA mutation frequency was significantly different between HPV-positive and HPV-negative cancers (P = .03). CONCLUSIONS AND RELEVANCE: Although there has been a suggestion that activating PIK3CA mutations are common in HPV-positive HNSCC, to our knowledge, this is the first study to clearly identify this phenomenon. Targeting PIK3CA with molecular agents in HPV-positive patients may be a mechanism to improve cure rates and decrease treatment toxic effects in this rapidly growing cohort of patients.

Does HPV type affect outcome in oropharyngeal cancer?

BACKGROUND: An epidemic of human papillomavirus (HPV)-related oropharyngeal squamous cell cancer (OPSCC) has been reported worldwide largely due to oral infection with HPV type-16, which is responsible for approximately 90% of HPV-positive cases. The purpose of this study was to determine the rate of HPV-positive oropharyngeal cancer in Southwestern Ontario, Canada. METHODS: A retrospective search identified ninety-five patients diagnosed with OPSCC. Pre-treatment biopsy specimens were tested for p16 expression using immunohistochemistry and for HPV-16, HPV-18 and other high-risk subtypes, including 31,33,35,39,45,51,52,56,58,59,67,68, by real-time qPCR. RESULTS: Fifty-nine tumours (62%) were positive for p16 expression and fifty (53%) were positive for known high-risk HPV types. Of the latter, 45 tumors (90%) were identified as HPV-16 positive, and five tumors (10%) were positive for other high-risk HPV types (HPV-18 (2), HPV-67 (2), HPV-33 (1)). HPV status by qPCR and p16 expression were extremely tightly correlated (p < 0.001, Fishers exact test). Patients with HPV-positive tumors had improved 3-year overall (OS) and disease-free survival (DFS) compared to patients with HPV-negative tumors (90% vs 65%, p = 0.001; and 85% vs 49%, p = 0.005; respectively). HPV-16 related OPSCC presented with cervical metastases more frequently than other high-risk HPV types (p = 0.005) and poorer disease-free survival was observed, although this was not statistically significant. CONCLUSION: HPV-16 infection is responsible for a significant proportion of OPSCC in Southwestern Ontario. Other high-risk subtypes are responsible for a smaller subset of OPSCC that present less frequently with cervical metastases and may have a different prognosis.

Most osteomalacia-associated mesenchymal tumors are a single histopathologic entity: an analysis of 32 cases and a comprehensive review of the literature.

Oncogenic osteomalacia (OO) is a rare paraneoplastic syndrome of osteomalacia due to phosphate wasting. The phosphaturic mesenchymal tumor (mixed connective tissue variant) (PMTMCT) is an extremely rare, distinctive tumor that is frequently associated with OO. Despite its association with OO, many PMTMCTs go unrecognized because they are erroneously diagnosed as other mesenchymal tumors. Expression of fibroblast growth factor-23 (FGF-23), a recently described protein putatively implicated in renal tubular phosphate loss, has been shown in a small number of mesenchymal tumors with known OO. The clinicopathological features of 32 mesenchymal tumors either with known OO (29) or with features suggestive of PMTMCT (3) were studied. Immunohistochemistry for cytokeratin, S-100, actin, desmin, CD34, and FGF-23 was performed. The patients (13 male, 19 female) ranged from 9 to 80 years in age (median 53 years). A long history of OO was common. The cases had been originally diagnosed as PMTMCT (15), hemangiopericytoma (HPC) (3), osteosarcoma (3), giant cell tumor (2), and other (9). The tumors occurred in a variety of soft tissue (21) and bone sites (11) and ranged from 1.7 to 14 cm. Twenty-four cases were classic PMTMCT with low cellularity, myxoid change, bland spindled cells, distinctive "grungy" calcified matrix, fat, HPC-like vessels, microcysts, hemorrhage, osteoclasts, and an incomplete rim of membranous ossification. Four of these benign-appearing PMTMCTs contained osteoid-like matrix. Three other PMTMCTs were hypercellular and cytologically atypical and were considered malignant. The 3 cases without known OO were histologically identical to the typical PMTMCT. Four cases did not resemble PMTMCT: 2 sinonasal HPC, 1 conventional HPC, and 1 sclerosing osteosarcoma. Three cases expressed actin; all other markers were negative. Expression of FGF-23 was seen in 17 of 21 cases by immunohistochemistry and in 2 of 2 cases by RT-PCR. Follow-up (25 cases, 6-348 months) indicated the following: 21 alive with no evidence of disease and with normal serum chemistry, 4 alive with disease (1 malignant PMTMCT with lung metastases). We conclude that most cases of mesenchymal tumor-associated OO, both in the present series and in the reported literature, are due to PMTMCT. Improved recognition of their histologic spectrum, including the presence of bone or osteoid-like matrix in otherwise typical cases and the existence of malignant forms, should allow distinction from other mesenchymal tumors. Recognition of PMTMCT is critical, as complete resection cures intractable OO. Immunohistochemistry and RT-PCR for FGF-23 confirm the role of this protein in PMTMCT-associated OO.