Prognostic value of tumor mutational burden in patients with oral cavity squamous cell carcinoma treated with upfront surgery

Background

Oral cavity is the most prevalent site of head and neck squamous cell carcinomas (HNSCCs). Most often diagnosed at a locally advanced stage, treatment is multimodal with surgery as the cornerstone. The aim of this study was to explore the molecular landscape of a homogenous cohort of oral cavity squamous cell carcinomas (OCSCCs), and to assess the prognostic value of tumor mutational burden (TMB), along with classical molecular and clinical parameters.

Patients and methods

One hundred and fifty-one consecutive patients with OCSCC treated with upfront surgery at the Institut Curie were analyzed. Sequencing of tumor DNA from frozen specimens was carried out using an in-house targeted next-generation sequencing panel (571 genes). The impact of molecular alterations and TMB on disease-free survival (DFS) and overall survival (OS) was evaluated in univariate and multivariate analyses.

Results

Pathological tumor stage, extranodal spread, vascular emboli, and perineural invasion were associated with both DFS and OS. TP53 was the most mutated gene (71%). Other frequent molecular alterations included the TERT promoter (50%), CDKN2A (25%), FAT1 (17%), PIK3CA (14%), and NOTCH1 (15%) genes. Transforming growth factor-β pathway alterations (4%) were associated with poor OS (P = 0.01) and DFS (P = 0.02) in univariate and multivariate analyses. High TMB was associated with prolonged OS (P = 0.01 and P = 0.02, in the highest 10% and 20% TMB values, respectively), but not with DFS. Correlation of TMB with OS remained significant in multivariate analysis (P = 0.01 and P = 0.005 in the highest 10% and 20% TMB values, respectively). Pathological tumor stage combined with high TMB was associated with good prognosis.

Conclusion

Our results suggest that a high TMB is associated with a favorable prognosis in patients with OCSCC treated with upfront surgery.

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High TMB is associated with a favorable prognosis in patients with OCSCC treated with upfront surgery

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Pathological tumor stage combined with high TMB is associated with good prognosis

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TP53 was the most mutated gene (71%). Other frequent molecular alterations included the TERT promoter (50%)

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TGFβ pathway alterations were associated with poor outcomes, although it was only observed in 4% of the patients

Combining immunotherapy with an epidrug in squamous cell carcinomas of different locations: rationale and design of the PEVO basket trial

Squamous cell carcinomas (SCCs) are among the most frequent solid tumors in humans. SCCs, related or not to the human papillomavirus, share common molecular features. Immunotherapies, and specifically immune checkpoint inhibitors, have been shown to improve overall survival in multiple cancer types, including SCCs. However, only a minority of patients experience a durable response with immunotherapy. Epigenetic modulation plays a major role in escaping tumor immunosurveillance and confers resistance to immune checkpoint inhibitors. Preclinical evidence suggests that modulating the epigenome might improve the efficacy of immunotherapy. We herein review the preclinical and the clinical rationale for combining immunotherapy with an epidrug, and detail the design of PEVOsq, a basket clinical trial combining pembrolizumab with vorinostat, a histone deacetylase inhibitor, in patients with SCCs of different locations. Sequential blood and tumor sampling will be collected in order to identify predictive and pharmacodynamics biomarkers of efficacy of the combination. We also present how clinical and biological data will be managed with the aim to enable the development of a prospective integrative platform to allow secure and controlled access to the project data as well as further exploitations.

Novel patterns of response under immunotherapy

Novel patterns of response and progression to immunotherapy have been reported that are not observed with conventional cytotoxic or targeted anticancer treatments. A major breakthrough with immunotherapy is its potential to achieve durable responses in a subset of patients with advanced cancer that can be maintained several years even after stopping the treatment. No standardized definition of durable response exists in the literature, and the optimal duration of treatment in case of durable response is not clearly established. However, the majority of patients do not respond to immunotherapy. Initially reported in advanced melanoma patients, pseudoprogression occurs when tumor index lesions regress after initial progression, supporting the concept of treating some patients beyond progression. Overall, reported rates of pseudoprogression never exceeded 10%, meaning that the large majority of patients who have a disease progression will not eventually respond to treatment. The decision to pursue treatment beyond progression must therefore only be taken in carefully selected patients with clinical benefit, who did not experience severe toxicities with immunotherapy. Conversely, rapid progressions, called hyperprogressions, were reported by several teams with rates ranging from 4% to 29%. These observations need to be confirmed from randomized trials. It is essential to interrupt the treatment in patients with hyperprogression, in order to switch to another potentially active treatment. Finally, some patients experience dissociated responses, with some lesions shrinking and others growing. Local treatment with surgery or radiotherapy for growing lesions may be considered. Several immune-specific-related response criteria were developed to better capture benefits of immunotherapy. These criteria only address the pseudoprogression pattern of response, and do not capture the other patterns of response such as hyperprogression and dissociated response. The classic RECIST remains a reasonable and meaningful method to assess response to immunotherapy in the clinic.

Abstract P6-17-25: PAM50 and CGH-array genomic characterization of HER2-equivocal breast cancers defined by the ASCO/CAP2013 recommendations and response to treatment

Background

HER2 breast cancer status determines patients' eligibility for targeted therapy. HER2 level of amplification is associated with a better response to anti-HER2 therapy (Arnould CCR 2007, Singer CCR 2017). Benefit of anti-HER2 therapy for equivocal cases remains debated.

Objectives

We aimed to better characterize HER2-equivocal breast cancers by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) according to 2013 ASCO/CAP guidelines using PAM50 gene expression-based molecular subtyping. We then investigated genome-wide copy number alterations of HER2-equivocal cases, assessing agreement between genomic alterations of the chromosome (chr) 17 and molecular subtypes.

Methods

PAM50 (nCounter assay; Nanostring) was performed on RNA from formalin-fixed paraffin-embedded samples of 40 HER2-equivocal cases. These cases were subsequently analyzed by Agilent 60-mer oligonucleotide microarrays for array-based comparative genomic hybridization (aCGH).

Results

The 40 HER2-equivocal cases were classified as Luminal B in 16 cases (40%), HER2-Enriched in 14 cases (35%), Luminal A in 9 cases (22.5%) and Basal-like in 1 case (2.5%) using PAM50.

By IHC, 34 cases (85%) were ER+, 24 (60%) were also PgR+, 26 (65%) were grade III and 33 (82.5%) showed a high Ki67 > 20%.

Using aCGH, 10 cases (25%) presented chr 17q large copy number gain, 10 (25%) showed segmental copy number gains including HER2, 9 (22.5%) showed HER2 amplification, one (2.5%) showed a large copy number loss and 10 cases (25%) didn't show any copy number alteration of the chr 17.

Out of the 14 PAM50 HER2-Enriched cases, only 5 (35.7%) showed HER2 genomic amplification (Table 1). Four HER2 amplified cases at the genomic level were classified as Luminal B (3 cases, Ki67 > 20%, ER+, PgR- by IHC) or Luminal A (1 case, Ki67<20%, ER+, PgR>10% by IHC) using PAM50, although these luminal B tumors presented strong correlation with the HER2-Enriched centroid. In total, 13 cases (32.5%) were discordant between molecular classification and genomic alteration status of the chr 17.

Among patients with early stage HER2-equivocal breast cancers (n=37), 2 received neo-adjuvant chemotherapy (5.4%), 25 received adjuvant chemotherapy (67.6%) and 2 received adjuvant trastuzumab (5.4%). With a median follow up of 5.8 years (3.8-6.9), one controlateral recurrence (2.7%), four metastatic recurrences (10.8%) and three deaths were observed (8.1%).

Conclusion

Using PAM50, the majority of HER2-equivocal cases were classified as Luminal tumors.

At the genomic level, HER2-equivocal cases harbored mostly chr 17 segmental or large copy number gains. These results emphasized the need of HER2 status genomic determination. In line with the new ASCO 2018 recommendations intending to decrease the number of cases considered as HER2 equivocal, we showed that these tumors were mainly HER2 not amplified, ER positive and grade 3. There is no evidence of benefit of anti-HER2 therapy in these cases.

Table 1Genomic alterations of chromosome 17Basal-likeHER2-EnrichedLuminal ALuminal BTotalHER2 amplified05139Large copy number gain013610Segmental copy number gain153110No alteration032510Large copy number loss00011Total11491640

Citation Format: Borcoman E, Ngo C, Rapinat A, Simaga F, Mariani O, Fuhrmann L, Jeannot E, Laé M, Pierga J-Y, Gentien D, Pierron G, Morel P, Brauer HA, Vincent-Salomon A. PAM50 and CGH-array genomic characterization of HER2-equivocal breast cancers defined by the ASCO/CAP2013 recommendations and response to treatment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-17-25.

Abstract P2-05-11: Not presented

This abstract was not presented at the symposium.