First-line avelumab treatment in patients with metastatic Merkel cell carcinoma: 4-year follow-up from part B of the JAVELIN Merkel 200 study

BACKGROUND

Results from the JAVELIN Merkel 200 study led to the approval of avelumab [an anti-programmed death-ligand 1 (PD-L1) antibody] for the treatment of metastatic Merkel cell carcinoma (mMCC) in multiple countries and its inclusion in the treatment guidelines as a preferred or recommended therapy in this setting. Here, we report 4-year follow-up results from the cohort of patients with mMCC who received avelumab as first-line treatment.

PATIENTS AND METHODS

In part B of JAVELIN Merkel 200, a single-arm, open-label, phase II study, patients with mMCC who had not received prior systemic therapy for metastatic disease received avelumab 10 mg/kg via intravenous infusion every 2 weeks until confirmed disease progression, unacceptable toxicity, or withdrawal. In this analysis, long-term overall survival (OS), patient disposition, and subsequent treatment were analyzed.

RESULTS

In total, 116 patients received first-line avelumab. At the data cutoff (2 February 2022), the median follow-up was 54.3 months (range 48.0-69.7 months). Seven patients (6.0%) remained on treatment and an additional 21 patients remained in follow-up (18.1%); 72 patients (62.1%) had died. The median OS was 20.3 months [95% confidence interval (CI) 12.4-42.0 months], with a 4-year OS rate of 38% (95% CI 29% to 47%). In patients with PD-L1+ or PD-L1- tumors, the 4-year OS rate was 48% (95% CI 26% to 67%) and 35% (95% CI 25% to 45%), respectively. In total, 48 patients (41.4%) received poststudy anticancer drug therapy, most commonly etoposide (20.7%), carboplatin (19.0%), and avelumab (12.1%).

CONCLUSIONS

Avelumab first-line monotherapy in patients with mMCC resulted in meaningful long-term OS, which compared favorably with historical studies of first-line chemotherapy. These results further support the role of avelumab as a standard of care for patients with mMCC.

Patient reported outcomes and patient experiences of immune checkpoint modulators for advanced or recurrent melanoma: a mixed methods study

PURPOSE

Little is known about late and long-term patient-reported outcomes (PROs) of immune checkpoint modulators (ICMs) outside clinical trials. We conducted a cross-sectional, mixed-methods study to describe long-term PROs among advanced melanoma patients who began standard of care treatment with ICMs at least 1 year previously.

METHODS

All participants completed the Functional Assessment of Cancer Therapy-Immune Checkpoint Modulator (FACT-ICM), assessing 46 immune-related side effects on a 5-point Likert scale, and a subset completed individual interviews. Descriptive statistics were computed for quantitative data and applied thematic analysis was used to examine qualitative data.

RESULTS

Participants (N = 80) had a mean age of 67 years, and the majority were male (66%), non-Hispanic White (96%), and college graduates (61%). Single-agent nivolumab was the most common first (47%) and current/recent ICM (64%). On the FACT-ICM, 98% of participants reported at least one side effect, and 78% reported moderate or severe side effects. The most common moderate or severe side effects were aching joints (43%) and fatigue (38%). In interviews (n = 20), we identified five themes regarding patients' longer-term experiences after ICMs: lasting fatigue or decline in functioning, minimal side effects, manageable thyroid and pituitary dysfunction, skin conditions can be difficult to manage, and treating the cancer is worth the side effects.

CONCLUSIONS

Nearly all patients reported side effects of ICMs at least 1 year after starting treatment. Our findings suggest that ICM side effect screening and management-especially for aching joints and fatigue-are indicated during long-term care of people living with advanced melanoma.

First-in-human stage III/IV melanoma​ clinical trial of immune priming agent IFx-Hu2.0

IFx-Hu2.0 was designed to encode part of the Emm55 protein contained within a plasmid in a formulation intended for transfection into mammalian cells. IFx-Hu2.0 promotes both adaptive and innate immune responses in animal studies. Furthermore, previous studies have demonstrated safety/efficacy in equine, canine, and murine species. We present the first-in-human study of IFx-Hu2.0, administered by intralesional injection into melanoma tumors of seven patients with stage III/IV unresectable melanoma. No dose-limiting toxicities attributable to IFx-Hu2.0 were observed. Grade 1/2 injection site reactions were observed in five of seven patients. IgG and IgM responses were seen in the peripheral blood to Emm55 peptides and known melanoma antigens, suggesting that IFx-Hu2.0 acts as an individualized "in-situ vaccine." Three of four patients previously refractory to anti-PD1 experienced clinical benefit upon subsequent anti-PD1-based treatment. Therefore, this approach is feasible, and clinical/correlative outcomes warrant further investigation for treating metastatic melanoma patients as an immune priming agent.

Ziv-aflibercept plus pembrolizumab in patients with advanced melanoma resistant to anti-PD-1 treatment

BACKGROUND

Vascular endothelial growth factor is associated with reduced immune response and impaired anti-tumor activity. Combining antiangiogenic agents with immune checkpoint inhibition can overcome this immune suppression and enhance treatment efficacy.

METHODS

This study investigated the combination of ziv-aflibercept anti-angiogenic therapy with pembrolizumab in patients with advanced melanoma resistant to anti-PD-1 treatment. Baseline and on-treatment plasma and PBMC samples were analyzed by multiplex protein assay and mass cytometry, respectively.

RESULTS

In this Phase 1B study (NCT02298959), ten patients with advanced PD-1-resistant melanoma were treated with a combination of ziv-aflibercept (at 2-4 mg/kg) plus pembrolizumab (at 2 mg/kg), administered intravenously every 2 weeks. Two patients (20%) achieved a partial response, and two patients (20%) experienced stable disease (SD) as the best response. The two responders had mucosal melanoma, while both patients with SD had ocular melanoma. The combination therapy demonstrated clinical activity and acceptable safety, despite the occurrence of adverse events. Changes in plasma analytes such as platelet-derived growth factor and PD-L1 were explored, indicating potential alterations in myeloid cell function. Higher levels of circulating CXCL10 in non-responding patients may reflect pro-tumor activity. Specific subsets of γδ T cells were associated with poor clinical outcomes, suggesting impaired γδ T-cell function in non-responding patients.

CONCLUSIONS

Although limited by sample size and follow-up, these findings highlight the potential of the combination of ziv-aflibercept antiangiogenic therapy with pembrolizumab in patients with advanced melanoma resistant to anti-PD-1 treatment and the need for further research to improve outcomes in anti-PD-1-resistant melanoma.

TRIAL REGISTRATION NUMBER

NCT02298959.

Combined BRAF, MEK, and heat-shock protein 90 inhibition in advanced BRAF V600-mutant melanoma

BACKGROUND

Resistance to BRAF and MEK inhibitors in BRAF V600-mutant melanoma is common. Multiple resistance mechanisms involve heat-shock protein 90 (HSP90) clients, and a phase 1 study of vemurafenib with the HSP90 inhibitor XL888 in patients with advanced melanoma showed activity equivalent to that of BRAF and MEK inhibitors.

METHODS

Vemurafenib (960 mg orally twice daily) and cobimetinib (60 mg orally once daily for 21 of 28 days) with escalating dose cohorts of XL888 (30, 45, 60, or 90 mg orally twice weekly) was investigated in a phase 1 trial of advanced melanoma, with a modified Ji dose-escalation design.

RESULTS

Twenty-five patients were enrolled. After two dose-limiting toxicities (DLTs) (rash and acute kidney injury) in the first cohort, lower doses of vemurafenib (720 mg) and cobimetinib (40 mg) were investigated with the same XL888 doses. Three DLTs (rash) were observed in 12 patients in the XL888 60-mg cohort, and this was determined as the maximum tolerated dose. Objective responses were observed in 19 patients (76%), and the median progression-free survival was 7.6 months, with a 5-year progression-free survival rate of 20%. The median overall survival was 41.7 months, with a 5-year overall survival rate of 37%. Single-cell RNA sequencing was performed on baseline and on-treatment biopsies; treatment was associated with increased immune cell influx (CD4-positive and CD8-positive T cells) and decreased melanoma cells.

CONCLUSIONS

Combined vemurafenib and cobimetinib plus XL888 had significant toxicity, requiring frequent dose reductions, which may have contributed to the relatively low progression-free survival despite a high tumor response rate. Given overlapping toxicities, caution must be used when combining HSP90 inhibitors with BRAF and MEK inhibitors.

Modeling phenotypic heterogeneity towards evolutionarily inspired osteosarcoma therapy

Osteosarcoma is the most common bone sarcoma in children and young adults. While universally delivered, chemotherapy only benefits roughly half of patients with localized disease. Increasingly, intratumoral heterogeneity is recognized as a source of therapeutic resistance. In this study, we develop and evaluate an in vitro model of osteosarcoma heterogeneity based on phenotype and genotype. Cancer cell populations vary in their environment-specific growth rates and in their sensitivity to chemotherapy. We present the genotypic and phenotypic characterization of an osteosarcoma cell line panel with a focus on co-cultures of the most phenotypically divergent cell lines, 143B and SAOS2. Modest environmental (pH, glutamine) or chemical perturbations dramatically shift the success and composition of cell lines. We demonstrate that in nutrient rich culture conditions 143B outcompetes SAOS2. But, under nutrient deprivation or conventional chemotherapy, SAOS2 growth can be favored in spheroids. Importantly, when the simplest heterogeneity state is evaluated, a two-cell line coculture, perturbations that affect the faster growing cell line have only a modest effect on final spheroid size. Thus the only evaluated therapies to eliminate the spheroids were by switching therapies from a first strike to a second strike. This extensively characterized, widely available system, can be modeled and scaled to allow for improved strategies to anticipate resistance in osteosarcoma due to heterogeneity.

Cetuximab for Immunotherapy-Refractory/Ineligible Cutaneous Squamous Cell Carcinoma

Anti-PD1 therapy demonstrated impressive, prolonged responses in advanced cutaneous squamous cell carcinoma (CSCC). Therapy for ICI-refractory/ineligible disease remains unclear. We performed a retrospective analysis in locally-advanced/metastatic CSCC using cetuximab across three cohorts: immediately after ICI failure (A), not immediately following ICI failure (B), or without prior ICI (C). The primary endpoint was the overall response rate (ORR). Secondary endpoints included disease-control rate (DCR), progression-free survival (PFS), overall survival (OS), time-to-response (TTR) and toxicity. Twenty-three patients were included. In cohort A (n = 11), the ORR was 64% and DCR was 91%, with six ongoing responses at data cutoff. In cohort B (n = 2), all patients had progression as the best response. At a median follow-up of 21 months for A and B, TTR and PFS were 2.0 and 17.3 months, respectively. The median OS was not reached. In cohort C (n = 10), the ORR and DCR were 80%, including five ongoing responses at the data cutoff. At a median follow-up of 22.4 months, the TTR, PFS and OS were 2.5, 7.3 and 23.1 months, respectively. Cetuximab was well tolerated in all cohorts. In summary, cetuximab is effective in patients with failure/contraindications to ICI. Cetuximab immediately after ICI failure yielded particularly fast, durable responses. If confirmed, this could be the preferred therapy following ICI failure.

Heritable defects in telomere and mitotic function selectively predispose to sarcomas

Cancer genetics has to date focused on epithelial malignancies, identifying multiple histotype-specific pathways underlying cancer susceptibility. Sarcomas are rare malignancies predominantly derived from embryonic mesoderm. To identify pathways specific to mesenchymal cancers, we performed whole-genome germline sequencing on 1644 sporadic cases and 3205 matched healthy elderly controls. Using an extreme phenotype design, a combined rare-variant burden and ontologic analysis identified two sarcoma-specific pathways involved in mitotic and telomere functions. Variants in centrosome genes are linked to malignant peripheral nerve sheath and gastrointestinal stromal tumors, whereas heritable defects in the shelterin complex link susceptibility to sarcoma, melanoma, and thyroid cancers. These studies indicate a specific role for heritable defects in mitotic and telomere biology in risk of sarcomas.

Phase II clinical and immune correlate study of adjuvant nivolumab plus ipilimumab for high-risk resected melanoma

BACKGROUND

Adjuvant therapy for high-risk resected melanoma with programmed cell-death 1 blockade results in a median relapse-free survival (RFS) of 5 years. The addition of low dose ipilimumab (IPI) to a regimen of adjuvant nivolumab (NIVO) in CheckMate-915 did not result in increased RFS. A pilot phase II adjuvant study of either standard dose or low dose IPI with NIVO was conducted at two centers to evaluate RFS with correlative biomarker studies.

METHODS

Patients with resected stages IIIB/IIIC/IV melanoma received either IPI 3 mg/kg and NIVO 1 mg/kg (cohort 4) or IPI 1 mg/kg and NIVO 3 mg/kg (cohorts 5 and 6) induction therapy every 3 weeks for 12 weeks, followed by maintenance NIVO. In an amalgamated subset of patients across cohorts, peripheral T cells at baseline and on-treatment were assessed by flow cytometry and RNA sequencing for exploratory biomarkers.

RESULTS

High rates of grade 3-4 adverse events precluded completion of induction therapy in 50%, 35% and 7% of the patients in cohorts 4, 5 and 6, respectively. At a median of 63.9 months of follow-up, 16/56 patients (29%) relapsed. For all patients, at 5 years, RFS was 71% (95% CI: 60 to 84), and overall survival was 94% (95% CI: 88 to 100). Expansion of CD3+CD4+CD38+CD127-GARP- T cells, an on-treatment increase in CD39 expression in CD8+ T cells, and T-cell expression of phosphorylated signal-transducer-and-activator-of-transcription (STAT)2 and STAT5 were associated with relapse.

CONCLUSIONS

Adjuvant IPI/NIVO at the induction doses used resulted in promising relapse-free and overall survival, although with a high rate of grade 3-4 adverse events. Biomarker analyses highlight an association of ectoenzyme-expressing T cells and STAT signaling pathways with relapse, warranting future validation.

TRIAL REGISTRATION NUMBER

NCT01176474 and NCT02970981.

Combined nivolumab and ipilimumab with or without stereotactic body radiation therapy for advanced Merkel cell carcinoma: a randomised, open label, phase 2 trial

BACKGROUND

Merkel cell carcinoma is among the most aggressive and lethal of primary skin cancers, with a high rate of distant metastasis. Anti-programmed death receptor 1 (anti-PD-1) and programmed death ligand 1 (PD-L1) monotherapy is currently standard of care for unresectable, recurrent, or metastatic Merkel cell carcinoma. We assessed treatment with combined nivolumab plus ipilimumab, with or without stereotactic body radiotherapy (SBRT) in patients with advanced Merkel cell carcinoma as a first-line therapy or following previous treatment with anti-PD-1 and PD-L1 monotherapy.

METHODS

In this randomised, open label, phase 2 trial, we randomly assigned adults from two cancer sites in the USA (one in Florida and one in Ohio) to group A (combined nivolumab and ipilimumab) or group B (combined nivolumab and ipilimumab plus SBRT) in a 1:1 ratio. Eligible patients were aged at least 18 years with histologically proven advanced stage (unresectable, recurrent, or stage IV) Merkel cell carcinoma, a minimum of two tumour lesions measureable by CT, MRI or clinical exam, and tumour tissue available for exploratory biomarker analysis. Patients were stratified by previous immune-checkpoint inhibitor (ICI) status to receive nivolumab 240 mg intravenously every 2 weeks plus ipilimumab 1 mg/kg intravenously every 6 weeks (group A) or the same schedule of combined nivolumab and ipilimumab with the addition of SBRT to at least one tumour site (24 Gy in three fractions at week 2; group B). Patients had to have at least two measurable sites of disease so one non-irradiated site could be followed for response. The primary endpoint was objective response rate (ORR) in all randomly assigned patients who received at least one dose of combined nivolumab and ipilimumab. ORR was defined as the proportion of patients with a complete response or partial response per immune-related Response Evaluation Criteria in Solid Tumours. Response was assessed every 12 weeks. Safety was assessed in all patients. This trial is registered with ClinicalTrials.gov, NCT03071406.

FINDINGS

50 patients (25 in both group A and group B) were enrolled between March 14, 2017, and Dec 21, 2021, including 24 ICI-naive patients (13 [52%] of 25 group A patients and 11 [44%] of 25 group B patients]) and 26 patients with previous ICI (12 [48%] of 25 group A patients and 14 [56%] of 25 group B patients]). One patient in group B did not receive SBRT due to concerns about excess toxicity. Median follow-up was 14·6 months (IQR 9·1-26·5). Two patients in group B were excluded from the analysis of the primary endpoint because the target lesions were irradiated and so the patients were deemed non-evaluable. Of the ICI-naive patients, 22 (100%) of 22 (95% CI 82-100) had an objective response, including nine (41% [95% CI 21-63]) with complete response. Of the patients who had previously had ICI exposure, eight (31%) of 26 patients (95% CI 15-52) had an objective response and four (15% [5-36]) had a complete response. No significant differences in ORR were observed between groups A (18 [72%] of 25 patients) and B (12 [52%] of 23 patients; p=0·26). Grade 3 or 4 treatment-related adverse events were observed in 10 (40%) of 25 patients in group A and 8 (32%) of 25 patients in group B.

INTERPRETATION

First-line combined nivolumab and ipilimumab in patients with advanced Merkel cell carcinoma showed a high ORR with durable responses and an expected safety profile. Combined nivolumab and ipilimumab also showed clinical benefit in patients with previous anti-PD-1 and PD-L1 treatment. Addition of SBRT did not improve efficacy of combined nivolumab and ipilimumab. The combination of nivolumab and ipilimumab represents a new first-line and salvage therapeutic option for advanced Merkel cell carcinoma.

FUNDING

Bristol Myers Squibb Rare Population Malignancy Program.

Classical epithelial-mesenchymal transition (EMT) and alternative cell death process-driven blebbishield metastatic-witch (BMW) pathways to cancer metastasis

Metastasis is a pivotal event that accelerates the prognosis of cancer patients towards mortality. Therapies that aim to induce cell death in metastatic cells require a more detailed understanding of the metastasis for better mitigation. Towards this goal, we discuss the details of two distinct but overlapping pathways of metastasis: a classical reversible epithelial-to-mesenchymal transition (hybrid-EMT)-driven transport pathway and an alternative cell death process-driven blebbishield metastatic-witch (BMW) transport pathway involving reversible cell death process. The knowledge about the EMT and BMW pathways is important for the therapy of metastatic cancers as these pathways confer drug resistance coupled to immune evasion/suppression. We initially discuss the EMT pathway and compare it with the BMW pathway in the contexts of coordinated oncogenic, metabolic, immunologic, and cell biological events that drive metastasis. In particular, we discuss how the cell death environment involving apoptosis, ferroptosis, necroptosis, and NETosis in BMW or EMT pathways recruits immune cells, fuses with it, migrates, permeabilizes vasculature, and settles at distant sites to establish metastasis. Finally, we discuss the therapeutic targets that are common to both EMT and BMW pathways.

Delivery of Online Adaptive MRI-Guided Radiation Therapy for a Deaf Patient

MRI-guided radiation therapy (MRgRT) enables real-time imaging during treatment and daily online adaptive planning. It is particularly useful for areas of treatment that have been previously excluded or restricted from ablative doses due to potential damage to adjacent normal tissue. In certain cases, ablative doses to metastatic lesions may be justified and treated with MRgRT using video-assisted gated breath-hold adjustments throughout delivery. The workflow relies on patient biofeedback and auditory cues.

A 74-year-old deaf male with a history of prostate cancer status post prostatectomy was found to have an enlarged cervical lymph node, which was excised with histopathology demonstrating Merkel cell carcinoma. Approximately one year after treatment with two cycles of pembrolizumab, which was subsequently discontinued due to toxicity, surveillance imaging demonstrated an enlarging left adrenal nodule. It was initially stable for an additional seven months with pembrolizumab rechallenge but was again found enlarged on subsequent imaging. The patient underwent MRg stereotactic body radiation therapy (MRgSBRT) to a total dose of 60 Gy in five fractions to this isolated site of progression. The patient was equipped with mirrored glasses to view the tracking structure with respect to gating the boundary structure, and the traditional reliance on verbal cues for coaching was reimagined to rely on visual cues instead. Follow-up positron emission tomography/CT (PET/CT) two weeks after treatment demonstrated interval resolution of the left adrenal metastatic nodule and a return to symmetric bilateral adrenal gland metabolic activity. The necessary MRgSBRT treatment for single metastatic lesions near normal tissue structures relies on verbal cues and coaching. However, deaf patients are unable to receive this treatment according to the traditional workflow model. Unique opportunities exist for the implementation of culturally competent care for the Deaf community, relying more heavily on visual cues, in radiation oncology practice.

Efficacy and Safety of TRC105 Plus Pazopanib vs Pazopanib Alone for Treatment of Patients With Advanced Angiosarcoma: A Randomized Clinical Trial

Question

Does the combination of pazopanib plus carotuximab improve progression-free survival compared with pazopanib alone in patients with advanced angiosarcoma?

Findings

This phase 3 randomized clinical trial of 123 patients found no significant difference in median progression-free survival between patients receiving pazopanib plus carotuximab compared with pazopanib alone.

Meaning

The study’s findings indicate that the combination of pazopanib plus carotuximab is not superior to pazopanib alone in treating patients with advanced angiosarcoma.

Importance

Angiosarcoma is a rare sarcoma subtype with a poor outcome. Carotuximab plus pazopanib produced a median progression-free survival (PFS) of 7.8 months in pazopanib-naive patients with chemotherapy-refractory angiosarcoma in a phase 1/2 trial.

Objective

To determine whether carotuximab plus pazopanib improves PFS compared with pazopanib alone in patients with advanced angiosarcoma.

Design, Setting, and Participants

The TAPPAS Trial: An Adaptive Enrichment Phase 3 Trial of TRC105 and Pazopanib vs Pazopanib Alone in Patients With Advanced Angiosarcoma was a multinational, multicenter, open-label, parallel-group, phase 3 randomized clinical trial of 123 patients 18 years or older with advanced angiosarcoma that was conducted between February 16, 2017, and April 12, 2019, at 31 sites in the US and the European Union. Patients were randomized 1:1 to receive pazopanib alone or carotuximab plus pazopanib. The trial incorporated an adaptive enrichment design. Inclusion criteria were no more than 2 prior lines of systemic therapy and an Eastern Cooperative Oncology Group performance status of 0 or 1. The efficacy analysis used the intent-to-treat population; the safety analysis included all patients who received a dose of either study drug.

Exposures

Oral pazopanib, 800 mg/d, or intravenous carotuximab, 10 mg/kg, administered weekly, plus oral pazopanib, 800 mg/d, with dose modification allowed per patient tolerance or until disease progression.

Main Outcomes and Measures

The primary end point was PFS, assessed by blinded independent radiographic and cutaneous photographic review per Response Evaluation Criteria in Solid Tumors (RECIST) guidelines, version 1.1. Secondary end points included the objective response rate and overall survival. An interim analysis to determine the final sample size was conducted after enrollment of 123 patients. PFS in the group receiving pazopanib alone was compared with PFS in the group receiving carotuximab plus pazopanib using the log rank test.

Results

Of 114 patients with evaluable data (53 in the pazopanib arm and 61 in the carotuximab plus pazopanib arm), 69 (61%) were female and the median age was 68 years (range, 24-82 years); 57 (50%) had cutaneous disease and 32 (28%) had had no prior treatment. The primary end point (PFS) was not reached (hazard ratio [HR], 0.98; 95% CI, 0.52-1.84; P = .95), with a median of 4.3 months (95% CI, 2.9 months to not reached) for pazopanib and 4.2 months (95% CI, 2.8-8.3 months) for the combination arm. The most common all-grade adverse events in the single-agent pazopanib arm vs the combination arm were fatigue (29 patients [55%] vs 37 [61%]), headache (12 patients [23%] vs 39 [64%]), diarrhea (27 patients [51%] vs 35 [57%]), nausea (26 patients [49%] vs 29 [48%]), vomiting (12 patients [23%] vs 23 [38%]), anemia (5 patients [9%] vs 27 [44%]), epistaxis (2 patients [4%] vs 34 [56%]), and hypertension (29 patients [55%] vs 22 [36%]).

Conclusions and Relevance

In this phase 3 randomized clinical trial, carotuximab plus pazopanib did not improve PFS compared with pazopanib alone in patients with advanced angiosarcoma.

Trial Registration

ClinicalTrials.gov Identifier: NCT02979899

Phase IB study of ziv-aflibercept plus pembrolizumab in patients with advanced solid tumors

BACKGROUND

The combination of antiangiogenic agents with immune checkpoint inhibitors could potentially overcome immune suppression driven by tumor angiogenesis. We report results from a phase IB study of ziv-aflibercept plus pembrolizumab in patients with advanced solid tumors.

METHODS

This is a multicenter phase IB dose-escalation study of the combination of ziv-aflibercept (at 2-4 mg/kg) plus pembrolizumab (at 2 mg/kg) administered intravenously every 2 weeks with expansion cohorts in programmed cell death protein 1 (PD-1)/programmed death-ligand 1(PD-L1)-naïve melanoma, renal cell carcinoma (RCC), microsatellite stable colorectal cancer (CRC), and ovarian cancer. The primary objective was to determine maximum tolerated dose (MTD) and recommended dose of the combination. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Exploratory objectives included correlation of clinical efficacy with tumor and peripheral immune population densities.

RESULTS

Overall, 33 patients were enrolled during dose escalation (n=3) and dose expansion (n=30). No dose-limiting toxicities were reported in the initial dose level. Ziv-aflibercept 4 mg/kg plus pembrolizumab 2 mg/kg every 2 weeks was established as the MTD. Grade ≥3 adverse events occurred in 19/33 patients (58%), the most common being hypertension (36%) and proteinuria (18%). ORR in the dose-expansion cohort was 16.7% (5/30, 90% CI 7% to 32%). Complete responses occurred in melanoma (n=2); partial responses occurred in RCC (n=1), mesothelioma (n=1), and melanoma (n=1). Median OS was as follows: melanoma, not reached (NR); RCC, 15.7 months (90% CI 2.5 to 15.7); CRC, 3.3 months (90% CI 0.6 to 3.4); ovarian, 12.5 months (90% CI 3.8 to 13.6); other solid tumors, NR. Activated tumor-infiltrating CD8 T cells at baseline (CD8+PD1+), high CD40L expression, and increased peripheral memory CD8 T cells correlated with clinical response.

CONCLUSION

The combination of ziv-aflibercept and pembrolizumab demonstrated an acceptable safety profile with antitumor activity in solid tumors. The combination is currently being studied in sarcoma and anti-PD-1-resistant melanoma.

TRIAL REGISTRATION NUMBER

NCT02298959.

OUP accepted manuscript

Background

Cancer of unknown primary (CUP) comprises a heterogeneous collection of malignancies that are typically associated with a poor prognosis and a lack of effective treatment options. We retrospectively evaluated the clinical utility of targeted next-generation sequencing (NGS) among CUP patients to assist with diagnosis and identify opportunities for molecularly guided therapy.

Patients and Methods

Patients with a CUP at Moffitt Cancer Center who underwent NGS between January 1, 2014 and December 31, 2019, were eligible for study inclusion. Next-generation sequencing results were assessed to determine the frequency of clinically actionable molecular alterations, and chart reviews were performed to ascertain the number of patients receiving molecularly guided therapy.

Results

Ninety-five CUP patients were identified for analysis. Next-generation sequencing testing identified options for molecularly guided therapy for 55% (n = 52) of patients. Among patients with molecularly guided therapy options, 33% (n = 17) were prescribed a molecularly guided therapy. The median overall survival for those receiving molecularly guided therapy was 23.6 months. Among the evaluable patients, the median duration of treatment for CUP patients (n = 7) receiving molecular-guided therapy as a first-line therapy was 39 weeks. The median duration of treatment for CUP patients (n = 8) treated with molecularly guided therapy in the second- or later-line setting was 13 weeks. Next-generation sequencing results were found to be suggestive of a likely primary tumor type for 15% (n = 14) of patients.

Conclusion

Next-generation sequencing results enabled the identification of treatment options in a majority of patients and assisted with the identification of a likely primary tumor type in a clinically meaningful subset of patients.

Immuno-transcriptomic profiling of extracranial pediatric solid malignancies

We perform an immunogenomics analysis utilizing whole-transcriptome sequencing of 657 pediatric extracranial solid cancer samples representing 14 diagnoses, and additionally utilize transcriptomes of 131 pediatric cancer cell lines and 147 normal tissue samples for comparison. We describe patterns of infiltrating immune cells, T cell receptor (TCR) clonal expansion, and translationally relevant immune checkpoints. We find that tumor-infiltrating lymphocytes and TCR counts vary widely across cancer types and within each diagnosis, and notably are significantly predictive of survival in osteosarcoma patients. We identify potential cancer-specific immunotherapeutic targets for adoptive cell therapies including cell-surface proteins, tumor germline antigens, and lineage-specific transcription factors. Using an orthogonal immunopeptidomics approach, we find several potential immunotherapeutic targets in osteosarcoma and Ewing sarcoma and validated PRAME as a bona fide multi-pediatric cancer target. Importantly, this work provides a critical framework for immune targeting of extracranial solid tumors using parallel immuno-transcriptomic and -peptidomic approaches.

Avelumab in patients with previously treated metastatic Merkel cell carcinoma (JAVELIN Merkel 200): updated overall survival data after >5 years of follow-up

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer that has a poor prognosis in patients with advanced disease. Avelumab [anti-programmed death-ligand 1 (PD-L1)] became the first approved treatment for patients with metastatic MCC (mMCC), based on efficacy and safety data observed in the JAVELIN Merkel 200 trial. We report long-term overall survival (OS) data after >5 years of follow-up from the cohort of patients with mMCC whose disease had progressed after one or more prior lines of chemotherapy.

PATIENTS AND METHODS

In Part A of the single-arm, open-label, phase II JAVELIN Merkel 200 trial, patients with mMCC that had progressed following one or more prior lines of chemotherapy received avelumab 10 mg/kg by intravenous infusion every 2 weeks until confirmed disease progression, unacceptable toxicity, or withdrawal. In this analysis, long-term OS was analyzed.

RESULTS

In total, 88 patients were treated with avelumab. At data cut-off (25 September 2020), median follow-up was 65.1 months (range 60.8-74.1 months). One patient (1.1%) remained on treatment, and an additional patient (1.1%) had reinitiated avelumab after previously discontinuing treatment. Median OS was 12.6 months [95% confidence interval (CI) 7.5-17.1 months], with a 5-year OS rate of 26% (95% CI 17% to 36%). In patients with PD-L1+ versus PD-L1- tumors, median OS was 12.9 months (95% CI 8.7-29.6 months) versus 7.3 months (95% CI 3.4-14.0 months), and the 5-year OS rate was 28% (95% CI 17% to 40%) versus 19% (95% CI 5% to 40%), respectively (HR 0.67; 95% CI 0.36-1.25).

CONCLUSION

Avelumab monotherapy resulted in meaningful long-term OS in patients with mMCC whose disease had progressed following chemotherapy. These results further support the role of avelumab as a standard of care for patients with mMCC.

First-line avelumab in a cohort of 116 patients with metastatic Merkel cell carcinoma (JAVELIN Merkel 200): primary and biomarker analyses of a phase II study

Background

Avelumab (anti-programmed death ligand 1 (PD-L1)) is approved in multiple countries for the treatment of metastatic Merkel cell carcinoma (mMCC), a rare and aggressive skin cancer. We report efficacy and safety data and exploratory biomarker analyses from a cohort of patients with mMCC treated with first-line avelumab in a phase II trial.

Methods

Patients with treatment-naive mMCC received avelumab 10 mg/kg intravenously every 2 weeks. The primary endpoint was durable response, defined as objective response (complete or partial response; assessed by independent review) lasting ≥6 months. Additional assessments included progression-free survival (PFS), overall survival (OS), safety, and biomarker analyses.

Results

In 116 patients treated with avelumab, median follow-up was 21.2 months (range: 14.9–36.6). Thirty-five patients had a response lasting ≥6 months, giving a durable response rate of 30.2% (95% CI: 22.0% to 39.4%). The objective response rate was 39.7% (95% CI: 30.7% to 49.2%). Median PFS was 4.1 months (95% CI: 1.4 to 6.1) and median OS was 20.3 months (95% CI: 12.4 to not estimable). Response rates were numerically higher in patients with PD-L1+ tumors, Merkel cell polyomavirus (MCPyV)-negative tumors, and tumors with increased intratumoral CD8⁺ T-cell density. Exploratory analyses did not identify a biomarker that could reliably predict a response to first-line treatment with avelumab; however, a novel gene expression signature to identify the presence of MCPyV+ tumors was derived. Treatment-related adverse events (any grade) occurred in 94 (81.0%) patients, including grade 3/4 events in 21 (18.1%) patients; no treatment-related deaths occurred.

Conclusion

In patients with mMCC, first-line treatment with avelumab led to responses in 40% and durable responses in 30%, and was associated with a low rate of grade 3/4 treatment-related adverse events.

An analysis of the use of targeted therapies in patients with advanced Merkel cell carcinoma and an evaluation of genomic correlates of response

Background

The use of targeted therapy remains a treatment consideration for some patients with advanced Merkel cell carcinoma (MCC). However, supportive data on the use of targeted therapy approaches are limited. Thus, we sought to evaluate the responsiveness of targeted agents in patients with advanced MCC.

Methods

An institutional MCC database identified patients who were treated with targeted therapy. For the purpose of this study, targeted therapy was defined as any multi‐targeted tyrosine kinase inhibitor or inhibitor of the PI3K‐pathway. Clinical benefit was defined as complete response, partial response, or stable disease (SD) ≥6 months. A subset of patient samples underwent next‐generation sequencing (NGS), Merkel cell polyomavirus testing, and PD‐L1/PD‐1 expression testing.

Results

Nineteen patients with MCC treated with targeted therapy were identified, 21 targeted therapy regimens were evaluable for response in 18 patients. Four of twenty‐one (19%) of evaluable regimens were associated with clinical benefit with the best overall response of SD. The durations of SD were 13.6 months (59 weeks), 9.7 months (42 weeks), 7.6 months (33 weeks), and 7.2 months (31 weeks). Of the four patients who derived clinical benefit, three were treated with pazopanib alone and one was treated with pazopanib plus everolimus. No difference in the rate of clinical benefit between molecular disease subtypes was detected nor was associated with any specific genomic alteration.

Conclusion

In our series, targeted agents elicited a disease control rate of 19% in patients with advanced MCC, with a best overall response of SD. Pazopanib alone or in combination exhibited a rate of disease control of 36% (4 of 11 with SD ≥6 months).

A Case of Retroperitoneal Synovial Sarcoma in Pregnancy Treated with Antepartum Doxorubicin plus Ifosfamide Chemotherapy

We report a case of a 25-year-old pregnant woman diagnosed with a large, unresectable retroperitoneal synovial sarcoma. Successful neoadjuvant treatment with doxorubicin plus ifosfamide prepartum and continuing postpartum resulted in significant disease response allowing for later tumor resection. Following the first prepartum chemotherapy cycle, a decreased amniotic fluid index was noted, representing a potential complication of chemotherapy. Induction of labor was performed at 33 weeks gestation with excellent outcome in the newborn. This case highlights the complex medical decision-making process in the setting of cancer diagnosed during pregnancy, balancing oncologic and obstetric concerns, and to our knowledge is only the second reported case of synovial sarcoma treated with neoadjuvant cytotoxic chemotherapy in the antepartum period.

Mutant p53s and chromosome 19 microRNA cluster overexpression regulate cancer testis antigen expression and cellular transformation in hepatocellular carcinoma

A subset of hepatocellular carcinoma (HCC) overexpresses the chromosome 19 miRNA cluster (C19MC) and is associated with an undifferentiated phenotype marked by overexpression of cancer testis antigens (CTAs) including anti-apoptotic melanoma-A antigens (MAGEAs). However, the regulation of C19MC miRNA and MAGEA expression in HCCs are not understood. Here we show that, C19MC overexpression is tightly linked to a sub-set of HCCs with transcription-incompetent p53. Using next-generation and Sanger sequencing we found that, p53 in Hep3B cells is impaired by TP53-FXR2 fusion, and that overexpression of the C19MC miRNA-520G in Hep3B cells promotes the expression of MAGEA-3, 6 and 12 mRNAs. Furthermore, overexpression of p53-R175H and p53-R273H mutants promote miR-520G and MAGEA RNA expression and cellular transformation. Moreover, IFN-γ co-operates with miR-520G to promote MAGEA expression. On the other hand, metals such as nickel and zinc promote miR-526B but not miR-520G, to result in the suppression of MAGEA mRNA expression, and evoke cell death through mitochondrial membrane depolarization. Therefore our study demonstrates that a MAGEA-promoting network involving miR-520G, p53-defects and IFN-γ that govern cellular transformation and cell survival pathways, but MAGEA expression and survival are counteracted by nickel and zinc combination.

Avelumab in patients with previously treated metastatic Merkel cell carcinoma: long-term data and biomarker analyses from the single-arm phase 2 JAVELIN Merkel 200 trial

Background

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer associated with a high risk of metastasis. In 2017, avelumab (anti–programmed death-ligand 1 (PD-L1)) became the first approved treatment for patients with metastatic MCC (mMCC), based on the occurrence of durable responses in a subset of patients. Here, we report long-term efficacy and safety data and exploratory biomarker analyses in patients with mMCC treated with avelumab.

Methods

In a cohort of this single-arm, phase 2 trial (JAVELIN Merkel 200), patients with mMCC and disease progression after prior chemotherapy received avelumab 10 mg/kg intravenously every 2 weeks. The primary endpoint was confirmed objective response rate (ORR) by independent review per Response Evaluation Criteria in Solid Tumors V.1.1. Other assessments included duration of response, progression-free survival, overall survival (OS), safety and biomarker analyses.

Results

As of 14 September 2018, 88 patients had been followed up for a median of 40.8 months (range 36.4–49.7 months). The ORR was 33.0% (95% CI 23.3% to 43.8%), including a complete response in 11.4% (10 patients), and the median duration of response was 40.5 months (95% CI 18.0 months to not estimable). As of 2 May 2019 (≥44 months of follow-up), the median OS was 12.6 months (95% CI 7.5 to 17.1 months) and the 42-month OS rate was 31% (95% CI 22% to 41%). Of long-term survivors (OS >36 months) evaluable for PD-L1 expression status (n=22), 81.8% had PD-L1+ tumors. In exploratory biomarker analyses, high tumor mutational burden (≥2 non-synonymous somatic variants per megabase) and high major histocompatibility complex class I expression (30% of tumors with highest expression) were associated with trends for improved ORR and OS. In long-term safety assessments (≥36 months of follow-up), no new or unexpected adverse events were reported, and no treatment-related deaths occurred.

Conclusions

Avelumab showed continued durable responses and meaningful long-term survival outcomes in patients with mMCC, reinforcing avelumab as a standard-of-care treatment option for this disease.

Trial registration number

NCT02155647

Avelumab in patients with previously treated Merkel cell carcinoma (JAVELIN Merkel 200): Updated overall survival data after more than five years of follow up

9517

Background: Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer. Although MCC is considered chemosensitive, patients typically have limited survival benefit with chemotherapy. Before the approval of immune checkpoint inhibitors, patients with metastatic MCC (mMCC) had a poor prognosis, with a historical 5-year overall survival (OS) rate of approximately 14%. Avelumab (anti–PD-L1) became the first approved treatment for patients with mMCC, based on efficacy and safety data observed in the phase 2 JAVELIN Merkel 200 trial (NCT02155647), in which patients with mMCC received avelumab monotherapy. We report the long-term OS data from the cohort of patients with mMCC whose disease had progressed after ≥1 prior line of chemotherapy. Methods: Eligible patients had histologically confirmed, measurable (per RECIST 1.1) stage IV MCC. Patients received avelumab 10 mg/kg by intravenous infusion every 2 weeks until confirmed disease progression, unacceptable toxicity, or withdrawal. Long-term OS was analyzed; updated data for other efficacy endpoints, including response and progression-free survival, were not obtained. Results: A total of 88 patients were enrolled and received avelumab treatment. As of September 25, 2020 (data cutoff), median follow-up was 65.1 months (range, 60.8-74.1 months). Median OS was 12.6 months (95% CI, 7.5-17.1 months); the 48- and 60-month OS rates were 30% (95% CI, 20%-40%) and 26% (95% CI, 17%-36%), respectively. At data cutoff, treatment was ongoing in 1 patient (1.1%) and an additional patient (1.1%) had reinitiated avelumab after previously discontinuing treatment. Reasons for treatment discontinuation were disease progression (n = 45 [51.1%]), adverse event (AE; n = 11 [12.5%]), death (n = 10 [11.4%]), withdrawal of consent (n = 9 [10.2%]), loss to follow-up (n = 1 [1.1%]), protocol noncompliance (n = 1 [1.1%]), and other reason (n = 10 [11.4%]). At data cutoff, 19 patients (21.6%) had discontinued treatment but remained in follow-up, and 63 patients (71.6%) had died; causes of death were disease progression (n = 49 [55.7%]), unknown reason (n = 9 [10.2%]), AE not related to study treatment (n = 3 [3.4%]), and other reason (n = 2 [2.3%]). In total, 26 patients (29.5%) received subsequent anticancer therapy; the most common subsequent therapies after trial discontinuation were avelumab (n = 4 [4.5%]), carboplatin and etoposide (n = 4 [4.5%]), and pembrolizumab (n = 4 [4.5%]). Conclusions: Avelumab monotherapy led to meaningful long-term OS in a subset of patients with mMCC whose disease had progressed after chemotherapy. These results further support the role of avelumab as a standard-of-care treatment for patients with mMCC. Clinical trial information: NCT02155647.

Efficacy of cetuximab after immunotherapy (IO) in advanced cutaneous squamous cell carcinoma (CSCC)

9562

Background: Anti-PD1 (aPD1) monotherapy with cemiplimab-rwlc or pembrolizumab is now considered standard of care for first-line management of advanced CSCC not amenable to surgery or curative radiotherapy. Previously chemotherapy or anti-EGFR agents were commonly used for these patients albeit with modest efficacy and limited duration of response. In prospective evaluation, the overall response rate (ORR) to cetuximab was 28% with disease control rate (DCR) of 69% at 6 weeks. The efficacy of second-line treatment following primary or acquired resistance to aPD1 therapy is not known. We investigated the activity of cetuximab in patients who progressed on previous IO therapy. Methods: We performed a single institution retrospective review from 9/28/18 (US approval date of cemiplimab-rwlc for CSCC) through 11/30/20 of patients with locally advanced or metastatic CSCC who received cetuximab after prior IO therapy. We identified patients who received cetuximab either immediately following IO therapy (cohort A) or as a subsequent line not immediately following IO therapy (cohort B). Primary endpoint was ORR with secondary endpoints of DCR, survival and toxicity. Median follow-up and survival times were calculated using the Kaplan-Meier method. Results: Thirteen patients, median age 72 years (62-82), all Caucasian, and 11 males (85%) were included in this study. Eleven pts received cetuximab immediately post-IO progression; two had additional intervening therapy post-IO before receiving cetuximab. Three patients received concurrent radiotherapy (palliative or definitive) with cetuximab. The ORR to cetuximab was 54% (7/13) including 1 complete and 6 partial responses. The cumulative 6-month DCR was 77%. All responses were observed in cohort A; both patients in cohort B had progressive disease as best response. Six of 7 initial responses are ongoing, including 3 in whom cetuximab was discontinued. At a median follow-up of 9.1 months, the median PFS has not been reached for the entire cohort. There were no unanticipated toxicities to cetuximab with rash (77%) and hypomagnesemia (54%) being the most common adverse events. Conclusions: In advanced CSCC, cetuximab used immediately after progression on aPD1 therapy yields notably higher and durable overall response than previously reported in the pre-IO therapy era. If validated in a larger dataset, this should be the preferred therapy for second-line treatment in advanced CSCC. Further exploration into the mechanism of this high efficacy of anti-EGFR therapy post aPD1 therapy is warranted.

Three-year survival, correlates and salvage therapies in patients receiving first-line pembrolizumab for advanced Merkel cell carcinoma

Background

Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with poor survival. Programmed cell death-1 (PD-1) pathway inhibitors have shown high rates of durable tumor regression compared with chemotherapy for MCC. The current study was undertaken to assess baseline and on-treatment factors associated with MCC regression and 3-year survival, and to explore the effects of salvage therapies in patients experiencing initial non-response or tumor progression after response or stable disease following first-line pembrolizumab therapy on Cancer Immunotherapy Trials Network-09/KEYNOTE-017.

Methods

In this multicenter phase II trial, 50 patients with advanced unresectable MCC received pembrolizumab 2 mg/kg every 3 weeks for ≤2 years. Patients were followed for a median of 31.8 months.

Results

Overall response rate to pembrolizumab was 58% (complete response 30%+partial response 28%; 95% CI 43.2 to 71.8). Among 29 responders, the median response duration was not reached (NR) at 3 years (range 1.0+ to 51.8+ months). Median progression-free survival (PFS) was 16.8 months (95% CI 4.6 to 43.4) and the 3-year PFS was 39.1%. Median OS was NR; the 3-year OS was 59.4% for all patients and 89.5% for responders. Baseline Eastern Cooperative Oncology Group performance status of 0, greater per cent tumor reduction, completion of 2 years of treatment and low neutrophil-to-lymphocyte ratio were associated with response and longer survival. Among patients with initial disease progression or those who developed progression after response or stable disease, some had extended survival with subsequent treatments including chemotherapies and immunotherapies.

Conclusions

This study represents the longest available follow-up from any first-line anti-programmed death-(ligand) 1 (anti-PD-(L)1) therapy in MCC, confirming durable PFS and OS in a proportion of patients. After initial tumor progression or relapse following response, some patients receiving salvage therapies survived. Improving the management of anti-PD-(L)1-refractory MCC remains a challenge and a high priority.

Trial registration number

NCT02267603.

Circulating Tumor Cells and Biomarker Modulation with Olaratumab Monotherapy Followed by Olaratumab plus Doxorubicin: Phase Ib Study in Patients with Soft-Tissue Sarcoma

This phase Ib study enumerated whole blood circulating tumor cells (CTC) and evaluated biomarkers in patients with potentially resectable soft-tissue sarcoma (STS) treated with olaratumab monotherapy (20 mg/kg) for one cycle followed by up to six cycles of olaratumab (20 mg/kg, cycles 1-2; 15 mg/kg, cycles 3-7) plus doxorubicin (75 mg/m² on day 1). CTCs, platelet-derived growth factor receptors (PDGFR), and PDGF ligand expression in tumor tissue pre- and post-olaratumab monotherapy were evaluated. Antitumor activity, safety, pharmacokinetics, and PET/biomarker association with clinical outcome were assessed. Of 51 treated patients, 35, 43, and 37 were evaluable for CTC enumeration, PDGFRs, and PDGF ligand expression, respectively. An increase in CTCs at cycle 1 day 8 was observed, followed by a significant reduction by cycle 3 day 1 or 30-day follow-up. Decrease in CTC counts after olaratumab monotherapy was higher in patients with disease control than without disease control (57.9% vs. 31.2%). Baseline IHC expression was positive in most patients for PDGFRα [n = 31 (72.1%)] and PDGFRβ [n = 36 (83.7%)]. Similar rates were observed post-olaratumab monotherapy [PDGFRα, n = 30 (69.8%); PDGFRβ, n = 33 (76.7%)]. Eleven patients (29.7%) showed a 30% reduction by RT-PCR in PDGFRα at cycle 2. PDGFR expression and PET response showed no correlation with clinical outcome. Safety and pharmacokinetic profiles were consistent with previous reports. This study, the first to use a validated method for CTC detection, confirms that CTC enumeration in STS is feasible. However, no correlation was observed between PDGFRα expression and clinical outcome.

Health-related quality of life trajectory of treatment-naive patients with Merkel cell carcinoma receiving avelumab

Aim: To evaluate changes in health-related quality of life (HRQoL) in a Phase II trial (NCT02155647) of treatment-naive patients with metastatic Merkel cell carcinoma treated with avelumab (15-month follow-up). Materials & methods: Mixed-effect Models for Repeated Measures were applied to HRQoL data (FACT-M; EQ-5D-5L) to assess changes over time. Clinically derived progression-free survival was compared with HRQoL deterioration-free survival. Results: Overall, we saw relative stability in HRQoL among 116 included patients, with nonprogression associated with statistically and clinically meaningful better HRQoL compared with progressive disease. Deterioration-free survival rates (49-72% at 6 months, 40-58% at 12 months) were consistently higher/better compared with progression-free survival rates (41/31% at 6/12 months). Conclusion: These findings show unique longitudinal HRQoL data for treatment-naive metastatic Merkel cell carcinoma patients treated with avelumab. Clinical trial registration: NCT02155647 (ClinicalTrials.gov).

TRIM28 congenital predisposition to Wilms' tumor: novel mutations and presentation in a sibling pair

Wilms’ tumor is the most common renal malignancy in children. In addition to staging, molecular risk stratification, such as loss of heterozygosity (LOH) in Chromosomes 1 and 16, is being increasingly used. Although genetic predisposition syndromes have been well-characterized in some Wilms’ tumors, recent sequencing and biology efforts are expanding the classification of this malignancy. Here we present a case of siblings with remarkably similar presentations of bilateral Wilms’ tumor at ∼12 mo of age. Thorough exam after the younger sibling was diagnosed did not reveal any signs to suggest one of the known Wilms’ predisposition syndromes. Both were treated with standard therapies with good response and long-term sustained complete remission of 53 and 97 mo, respectively. Whole-exome sequencing was performed on a tumor sample from each patient and matched blood from one, revealing a shared truncation mutation of TRIM28 in all three samples with heterozygosity in the germline sample. TRIM28 loss has been recently implicated in early-stage Wilms’ tumors with epithelioid morphology. These siblings expand the phenotype for presentation with multifocal disease with retained excellent response to standard therapy.

Abstract 3445: Immuno-transcriptomic profiling identifies actionable genomic alterations in pediatric solid malignancies

Malignancy remains the leading cause of disease-related death in children. To identify potential tumor-driving molecular targets and characterize immunogenomic profiles in pediatric cancers, we performed RNA-seq analysis on a cohort of 788 pediatric solid tumors across 14 different diagnoses in conjunction with additional 147 normal tissues for comparison. Sequencing data were analyzed for expressed mutations, fusion events, and expressional patterns, providing therapeutic targets and rich cancer biology for these childhood cancers. Furthermore, we describe a comprehensive and in-depth immunogenomic landscape of these solid tumors including immune cell infiltrate, neoepitope analysis from expressed mutations and fusions, expressional patterns of clinically relevant immune checkpoint genes, expression of tumor-specific genes as potential pharmacological or immunological targets, and T cell receptor repertoire. Across the cohort, we observed a striking correlation between the expressed neoepitope burden in tumors and enrichment of the effector immune signatures. Intriguingly, canonical fusions (e.g. EWS-FLI1) contribute a disproportionally large number of neoepitopes in these typically low mutational tumors. Histology-specific immunogenomic patterns are also apparent. Several of the pediatric cancers such as alveolar soft part sarcoma and osteosarcoma exhibit rich immune cell infiltration and evidence for activated T cell activities, whereas others such as Wilms tumors and synovial sarcoma generally have a very low T cell infiltration. In addition, we demonstrated a significant positive correlation between tumor-infiltrating CD8+ T cells and overall survival in patients with osteosarcoma, revealing the clinical importance of these tumor-infiltrating immune cells in these childhood cancers. Moreover, an orthogonal evaluation of immunopeptidome in osteosarcoma, a cancer type displaying high immune infiltrates, confirmed our transcriptomic findings on potential targetable tumor-specific genes. Finally, we took an adoptive cell therapy-based approach to target a tumor-specific gene PRAME identified by our transcriptomic and immunopeptidomic studies and showed significant in-vitro cytotoxicity using T cells expressing TCRs specifically targeting PRAME in osteosarcoma U2OS cells. Therefore, we demonstrate that RNA-seq is a powerful tool to identify clinically relevant and histology-specific genomic alterations and translationally relevant immunogenomic patterns for pediatric cancers. This study also represents one of the largest of its type to date and provides a framework for future translational efforts in pediatric cancer.

Citation Format: Jun S. Wei, Andrew S. Brohl, Sivasish Sindiri, David Milewski, Young K. Song, Sushma Nagaraj, Vineela Gangalapudi, Xinyu Wen, Marc Ladanyi, Javed Khan. Immuno-transcriptomic profiling identifies actionable genomic alterations in pediatric solid malignancies [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3445.

Abstract PR17: Immunogenomic landscape of pediatric solid malignancies

Malignancy remains the leading cause of disease-related death in children. To identify potential tumor-driving molecular targets and immunogenomic profiles in pediatric cancers, we performed RNA-seq analysis on a cohort of 788 pediatric solid malignant tumors across 14 different diagnoses in conjunction with additional 147 normal tissues for comparison. Sequencing data were analyzed for expressed mutations, fusion events, and expressional patterns, providing therapeutic targets and rich cancer biology for these childhood cancers. Furthermore, we describe immunogenomic features of these solid tumors including immune cell infiltrate, neoantigen expression, expression of immunomodulatory molecules, and T-cell receptor repertoire. Across the cohort, we observed a striking correlation between the expressed neoantigen burden in tumors and enrichment of the effector immune signatures. Histology-specific immunogenomic patterns were also apparent. Several of the pediatric cancers such as alveolar soft part sarcoma and osteosarcoma exhibit rich immune cell infiltration and evidence for activated T-cell activities, whereas others such as Wilms’ tumors and synovial sarcoma generally have a very low T-cell infiltration. We demonstrate that RNA-seq is a powerful tool to identify clinically relevant and histology-specific recurrent mutations, novel oncogenic fusions, and translationally relevant immunogenomic patterns for pediatric cancers. This study also represents one of the largest of its type to date and provides a framework for future translational efforts in pediatric cancer.

This abstract is also being presented as Poster A69.

Citation Format: Jun S. Wei, Andrew S. Brohl, Sivasish Sindiri, Young K. Song, Sushma Najaraj, Vineela Gangalapudi, Xinyu Wen, Marc Ladanyi, Javed Khan. Immunogenomic landscape of pediatric solid malignancies [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr PR17.

Chemotherapy improves distant control in localized high-grade soft tissue sarcoma of the extremity/trunk

Background

Soft tissue sarcomas (STS) are rare and heterogeneous tumors making chemotherapy use controversial. Our goal was to identify a subset of patients with primary STS that benefit with the addition of chemotherapy.

Methods

A retrospective chart review included intermediate to high-grade localized primary STS of the extremity/trunk, and tumor size > 5 cm. The effect of chemotherapy was evaluated for local control (LC), distant control (DC), progression free survival (PFS), and overall survival (OS).

Results

In this cohort (n = 273), patients were treated with surgery (98%), radiation (81%), and chemotherapy (24.5%). With a median follow-up of 51 months, the entire cohort’s 5-year LC, DC, PFS, and OS are 79.1%, 59.9%, 43.8%, and 68.7%, respectively. The addition of chemotherapy did not provide a DC benefit (p = 0.238) for the entire cohort. High-grade disease (n = 210) experienced a 5-year benefit in DC (68% vs. 54.4%, p = 0.04), which was more pronounced with MAI (Mesna, Adriamycin, Ifosfamide) based regimens (74.2%, p = 0.016), and a 5-year PFS (50.8% vs 45%, p = 0.025) and OS benefit (76.2% vs 70%, p = 0.067) vs. no chemotherapy. On multivariate analysis of the high-grade subset, chemotherapy independently predicted for a DC benefit (HR 0.48 95% CI 0.26–89, p = 0.019). The benefit of chemotherapy was more pronounced with MAI, showing a significant benefit in DC (HR 0.333 95% CI 0.145–0.767, p = 0.01) and PFS (HR 0.52 95% CI 0.28–0.99, p = 0.047).

Conclusion

In patients with localized STS > 5 cm, the high-grade subset had a distant control benefit with the addition of chemotherapy, leading to improved progression free survival. This is more pronounced with the use of MAI and should be considered in patients eligible for this regimen.

Neoadjuvant Checkpoint Inhibitor Therapy for Merkel Cell Carcinoma

A 78-year-old man presented with rapidly enlarging lymph nodes in the right preauricular region and neck. Needle biopsy revealed a cytokeratin 20-positive, high-grade neuroendocrine neoplasm consistent with Merkel cell carcinoma (MCC). Cross-sectional imaging disclosed a 5.2-cm intraparotid mass and extensive adenopathy in the ipsilateral cervical and submental chains (Figs 1A and 1C), without distant metastatic disease. A skin examination did not reveal a primary lesion (hence, stage IIIA, T0N1bM0). The patient's history was notable for hypertension, diet-controlled diabetes type II, high cholesterol, and a past history of numerous cutaneous basal and squamous cell carcinomas. He was quite active but reported discomfort from the bulk of the tumors. The patient was evaluated by the surgical oncology team, who believed that the parotid mass and cervical adenopathy were technically resectable but that resection carried a substantial risk of morbidity because of the potential need to sacrifice the facial and/or spinal accessory nerves and because of a likely margin-positive (R1 or R2) result. He was referred to the medical oncology team to discuss management options for regionally advanced, "borderline-resectable" MCC.

The genomic landscape of undifferentiated embryonal sarcoma of the liver is typified by C19MC structural rearrangement and overexpression combined with TP53 mutation or loss

Undifferentiated embryonal sarcoma of the liver (UESL) is a rare and aggressive malignancy. Though the molecular underpinnings of this cancer have been largely unexplored, recurrent chromosomal breakpoints affecting a noncoding region on chr19q13, which includes the chromosome 19 microRNA cluster (C19MC), have been reported in several cases. We performed comprehensive molecular profiling on samples from 14 patients diagnosed with UESL. Congruent with prior reports, we identified structural variants in chr19q13 in 10 of 13 evaluable tumors. From whole transcriptome sequencing, we observed striking expressional activity of the entire C19MC region. Concordantly, in 7 of 7 samples undergoing miRNAseq, we observed hyperexpression of the miRNAs within this cluster to levels >100 fold compared to matched normal tissue or a non-C19MC amplified cancer cell line. Concurrent TP53 mutation or copy number loss was identified in all evaluable tumors with evidence of C19MC overexpression. We find that C19MC miRNAs exhibit significant negative correlation to TP53 regulatory miRNAs and K-Ras regulatory miRNAs. Using RNA-seq we identified that pathways relevant to cellular differentiation as well as mRNA translation machinery are transcriptionally enriched in UESL. In summary, utilizing a combination of next-generation sequencing and high-density arrays we identify the combination of C19MC hyperexpression via chromosomal structural event with TP53 mutation or loss as highly recurrent genomic features of UESL.

The genetic script of metastasis

Metastasis is a pivotal event that changes the course of cancers from benign and treatable to malignant and difficult to treat, resulting in the demise of patients. Understanding the genetic control of metastasis is thus crucial to develop efficient and sustainable targeted therapies. Here we discuss the alterations in epigenetic mechanisms, transcription, chromosomal instability, chromosome imprinting, non-coding RNAs, coding RNAs, mutant RNAs, enhancers, G-quadruplexes, and copy number variation to dissect the genetic control of metastasis. We conclude that the genetic control of metastasis is predominantly executed through epithelial to mesenchymal transition and evasion of cell death. We discuss how genetic regulatory mechanisms can be harnessed for therapeutic purposes to achieve sustainable control over cancer metastasis.

Neoadjuvant BRAF-targeted therapy in regionally advanced and oligometastatic melanoma

Current management of locoregional and oligometastatic melanoma is typically with surgery; however, some patients are unable to undergo resection due to location/size of their tumors and/or the anticipated morbidity of the surgery. While there are currently no established guidelines for neoadjuvant therapy in melanoma, neoadjuvant BRAF-targeted therapy may make resection more feasible. A retrospective analysis was conducted of 23 patients with BRAFV600-mutant, stage III/IV melanoma treated with BRAF-targeted therapy prior to surgery, with no adjuvant treatment. Surgical specimens, preoperative imaging, and clinical outcomes were evaluated. Results: Ten of 23 patients (44%) attained a pathologic complete response (pCR), with no correlation between RECIST response based on preoperative imaging and pathologic response. After a median of 43-month follow-up, only 1 patient (10%) with a pCR recurred, while 8 of 13 (62%) patients without a pCR recurred. Patients with a pCR had significantly improved relapse-free (RFS) and overall survival (OS) compared to patients with residual tumor. Neoadjuvant BRAF-targeted therapy is associated with a high pCR rate in patients with stage III-IV melanoma, which may correlate with improved RFS and OS.

Clinical, pathological, and genomic features of EWSR1-PATZ1 fusion sarcoma

Molecular diagnostics of sarcoma subtypes commonly involve the identification of characteristic oncogenic fusions. EWSR1-PATZ1 is a rare fusion partnering in sarcoma, with few cases reported in the literature. In the current study, a series of 11 cases of EWSR1-PATZ1 fusion positive malignancies are described. EWSR1-PATZ1-related sarcomas occur across a wide age range and have a strong predilection for chest wall primary site. Secondary driver mutations in cell-cycle genes, and in particular CDKN2A (71%), are common in EWSR1-PATZ1 sarcomas in this series. In a subset of cases, an extended clinical and histopathological review was performed, as was confirmation and characterization of the fusion breakpoint revealing a novel intronic pseudoexon sequence insertion. Unified by a shared gene fusion, EWSR1-PATZ1 sarcomas otherwise appear to exhibit divergent morphology, a polyphenotypic immunoprofile, and variable clinical behavior posing challenges for precise classification.

The Genomic Landscape of Merkel Cell Carcinoma and Clinicogenomic Biomarkers of Response to Immune Checkpoint Inhibitor Therapy

PURPOSE

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy, which has demonstrated sensitivity to immune checkpoint inhibitor therapy. Here, we perform the largest genomics study in MCC to date to characterize the molecular landscape and evaluate for clinical and molecular correlates to immune checkpoint inhibitor response.

EXPERIMENTAL DESIGN

Comprehensive molecular profiling was performed on 317 tumors from patients with MCC, including the evaluation of oncogenic mutations, tumor mutational burden (TMB), mutational signatures, and the Merkel cell polyomavirus (MCPyV). For a subset of 57 patients, a retrospective analysis was conducted to evaluate for clinical and molecular correlates to immune checkpoint inhibitor response and disease survival.

RESULTS

Genomic analyses revealed a bimodal distribution in TMB, with 2 molecularly distinct subgroups. Ninety-four percent (n = 110) of TMB-high specimens exhibited an ultraviolet light (UV) mutational signature. MCPyV genomic DNA sequences were not identified in any TMB-high cases (0/117), but were in 63% (110/175) of TMB-low cases. For 36 evaluable patients treated with checkpoint inhibitors, the overall response rate was 44% and response correlated with survival at time of review (100% vs. 20%, P < 0.001). Response rate was 50% in TMB-high/UV-driven and 41% in TMB-low/MCPyV-positive tumors (P = 0.63). Response rate was significantly correlated with line of therapy: 75% in first-line, 39% in second-line, and 18% in third-line or beyond (P = 0.0066). PD-1, but not PD-L1, expression was associated with immunotherapy response (77% vs. 21%, P = 0.00598, for PD-1 positive and negative, respectively).

CONCLUSIONS

We provide a comprehensive genomic landscape of MCC and demonstrate clinicogenomic associates of immunotherapy response.

Abstract 3653: Immunogenomic landscape of pediatric solid malignancies

Malignancy remains the leading cause of disease-related death in children. To identify potential tumor-driving molecular targets and immunogenomic profiles in pediatric cancers, we performed RNA-seq analysis on a cohort of 792 pediatric solid malignant tumors across 14 different diagnoses in conjunction with additional 147 normal tissues for comparison. Sequencing data was analyzed for expressed mutations, fusion events, and expressional patterns, providing therapeutic targets and rich cancer biology for these childhood cancers. Furthermore, we describe immunogenomic features of the tumors including immune cell infiltrate, neoantigen expression, expression of immunomodulatory molecules, and T cell receptor repertoire. Across the cohort, we observed a striking correlation between the expressed neoantigen burden in tumors and enrichment of the effector immune signatures. Histology-specific immunogenomic patterns were also apparent. Several of the pediatric cancers such as alveolar soft part sarcoma and osteosarcoma exhibit rich immune cell infiltration and evidence for activated T cell activities, whereas others such as Ewing’s sarcoma and yolk sac tumors generally have a very low T cell infiltration. We demonstrate that RNA-seq is a powerful tool to identify clinically relevant and histology-specific recurrent mutations, novel oncogenic fusions, and translationally relevant immunogenomic patterns for pediatric cancers. This study also represents one of the largest of its type to date and provides a framework for future translational efforts in pediatric cancer.

Citation Format: Jun S. Wei, Andrew S. Brohl, Young K. Song, Sushma Najaraj, Vineela Gangalapudi, Ashley Walton, Xinyu Wen, Marc Ladanyi, Javed Khan. Immunogenomic landscape of pediatric solid malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3653.

Abstract 3010: Osteosarcoma cell lines display both shared and unique vulnerabilities to 140 targeted small molecules with RNA-seq revealing putative mechanisms

BACKGROUND: Osteosarcoma is the most common bone sarcoma in children, adolescents, and young adults. Osteosarcoma primarily arises through tumor suppressor inactivation, most typically due to TP53 attenuation mechanisms. Increasingly additional oncogenic and tumor suppressor pathways are being recognized in subsets of osteosarcoma. We hypothesized that novel insights into mechanisms of sensitivity and resistance for emerging targeted therapies could be elucidated by combining activity and genomic information across cell line models of osteosarcoma.

METHODS: In this study we evaluated 6 established osteosarcoma cell lines (U2-OS, MG-63, OS252, SAOS-2, 143B, MNNG) representing several TP53 and other tumor suppressor inactivation mechanisms with human osteoblasts as a control. We have obtained RNA-seq profiles detailing genomic variants, gene fusions, and expression of both protein-coding and miRNA genes for these cell lines. In addition to genomic changes, we evaluated 140 chemical probes and candidate drug molecules across these cell lines.

RESULTS: RNAseq identified TP53 changes in 5 of 6 cell lines with OS252, SAOS2 and MG-63 having intron 1 translocations and 143B and MNNG sharing a TP53 gain-of-function mutation. Variant calling from the whole exome sequencing data revealed additional putatively oncogenic mutations. Additionally, we observed differential gene expression patterns compared to control samples in genes associated with genomic stability, epigenetic regulation, and transcriptional activity. Differential sensitivities to several classes of small molecules were seen across the cell lines and were associated with genomic changes that warrant additional investigation such as: RAD51 pathway genomic findings associated with sensitivity to RS-1, disulfuram activity varying according to aldehyde dehydrogenase activity, and variable response to inhibitors of ATR and specific CDKs that are associated with the expression of their respective targets. Additional pathways of interest that demonstrate differential response to small molecules include histone/protein deacetylation, telomerase activity, protein translation, and others. Unique vulnerabilities associated with tumor suppressor or oncogenic changes specific to an individual cell line will be presented.

CONCLUSIONS: By characterizing response to small molecules in the context of gene expression, underlying pathway vulnerabilities may be determined for further testing suggesting potential biomarkers for basket trials. Other agents with shared sensitivities to agents across cell lines may be translated in a different manner.

Citation Format: Elliot J. Kahen, Darcy Welch, Jamie Teer, Andrew S. Brohl, Sean J. Yoder, Yonghong Zhang, Ling Cen, Damon Reed. Osteosarcoma cell lines display both shared and unique vulnerabilities to 140 targeted small molecules with RNA-seq revealing putative mechanisms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3010.

Early objective response to avelumab treatment is associated with improved overall survival in patients with metastatic Merkel cell carcinoma

BACKGROUND

Response rates are primary endpoints in many oncology trials; however, correlation with overall survival (OS) is not uniform across cancer types, treatments, or lines of therapy. This study explored the association between objective response (OR) and OS in patients with chemotherapy-refractory metastatic Merkel cell carcinoma who received avelumab (anti-PD-L1).

METHODS

Eighty-eight patients enrolled in JAVELIN Merkel 200 (part A; NCT02155647) received i.v. avelumab 10 mg/kg every 2 weeks until confirmed progression, unacceptable toxicity, or withdrawal. Using conditional landmark analyses, we compared OS in patients with and without confirmed OR (RECIST v1.1). We applied a Cox model that included OR as a time-varying covariate and adjusted for age, visceral disease, and number of previous therapies.

RESULTS

Twenty-nine patients had confirmed OR; 20 by study week 7 and 7 more between study weeks 7 and 13. Survival probabilities 18 months after treatment initiation were 90% [95% confidence interval (CI) 65.6-97.4] in patients with OR at week 7 and 26.2% (95% CI 15.7-37.8) in patients without OR but who were alive at week 7. Median OS was not reached in patients with OR and was 8.8 months (95% CI 6.4-12.9) in patients without. Similar results were observed for the week 13 landmark. The adjusted Cox model showed OR was associated with a 95% risk reduction of death [hazard ratio 0.052 (95% CI 0.018-0.152)] compared with a nonresponse.

CONCLUSIONS

Patients with OR by 7 or 13 weeks had significantly longer OS than patients without, confirming that early OR is an endpoint of major importance.

Durable Tumor Regression and Overall Survival in Patients With Advanced Merkel Cell Carcinoma Receiving Pembrolizumab as First-Line Therapy

PURPOSE

Merkel cell carcinoma (MCC) is an aggressive skin cancer often caused by the Merkel cell polyomavirus. Clinical trials of programmed cell death-1 pathway inhibitors for advanced MCC (aMCC) demonstrate increased progression-free survival (PFS) compared with historical chemotherapy data. However, response durability and overall survival (OS) data are limited.

PATIENTS AND METHODS

In this multicenter phase II trial (Cancer Immunotherapy Trials Network-09/Keynote-017), 50 adults naïve to systemic therapy for aMCC received pembrolizumab (2 mg/kg every 3 weeks) for up to 2 years. Radiographic responses were assessed centrally per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

RESULTS

Among 50 patients, the median age was 70.5 years, and 64% had Merkel cell polyomavirus-positive tumors. The objective response rate (ORR) to pembrolizumab was 56% (complete response [24%] plus partial response [32%]; 95% CI, 41.3% to 70.0%), with ORRs of 59% in virus-positive and 53% in virus-negative tumors. Median follow-up time was 14.9 months (range, 0.4 to 36.4+ months). Among 28 responders, median response duration was not reached (range, 5.9 to 34.5+ months). The 24-month PFS rate was 48.3%, and median PFS time was 16.8 months (95% CI, 4.6 months to not estimable). The 24-month OS rate was 68.7%, and median OS time was not reached. Although tumor viral status did not correlate with ORR, PFS, or OS, there was a trend toward improved PFS and OS in patients with programmed death ligand-1-positive tumors. Grade 3 or greater treatment-related adverse events occurred in 14 (28%) of 50 patients and led to treatment discontinuation in seven (14%) of 50 patients, including one treatment-related death.

CONCLUSION

Here, we present the longest observation to date of patients with aMCC receiving first-line anti-programmed cell death-1 therapy. Pembrolizumab demonstrated durable tumor control, a generally manageable safety profile, and favorable OS compared with historical data from patients treated with first-line chemotherapy.

Precision medicine approaches for the management of Ewing sarcoma: current perspectives

Advancements in molecular and genetic techniques have significantly furthered our biological understanding of Ewing sarcoma (ES). ES is typified by a driving TET-ETS fusion with an otherwise relatively quiet genome. Detection of one of several characteristic fusions, most commonly EWSR1-FLI1, is the gold standard for diagnosis. We discuss the current role of precision medicine in the diagnosis, treatment, and monitoring of ES. Continued efforts toward molecularly guided approaches are actively being pursued in ES to better refine prognosis, identify germline markers of disease susceptibility, influence therapeutic selection, effectively monitor disease activity in real time, and identify genetic and immunotherapeutic targets for therapeutic development.

Clinical Utility of Genomic Profiling in the Treatment of Advanced Sarcomas: A Single-Center Experience

Purpose

Sarcomas are a diverse group of malignant tumors that arise from soft tissues or bone. For most advanced cases, there is a substantial need for improved therapeutic options and, therefore, a desire to more precisely tailor therapy in individual cases. In this study, we review our institutional experience with next-generation sequencing (NGS)–based molecular profiling for non–GI stromal tumors sarcomas, with a focus on the clinical utility of the results.

Patients and Methods

We retrospectively analyzed results of NGS performed on tumors from 114 patients with a diagnosis of sarcoma. A chart review was conducted to review the clinical impact of NGS findings.

Results

A median of three putatively oncogenic gene alterations were identified per tumor sample (range, 0 to 19) and at least one mutation was detected in 96.7% of tumors. Fifty-six patients (49.1%) harbored a finding that was felt to be actionable after review by a molecular tumor board. Five patients (4.4%) had a diagnosis change as a result of NGS findings. In 15 patients (13.2%), therapeutic selection was influenced by NGS findings. Four of 15 (26.7%) of the NGS-influenced systemic therapies resulted in clinical benefit.

Conclusion

Putatively oncogenic mutations are readily detected in the majority of sarcomas. Genetic profiling affected the diagnosis and/or treatment approach in a sizeable minority of patients with sarcoma treated at our center. Additional study is required to determine if genetic profiling leads to improved clinical outcomes.

Identification of a novel MTAP-RAF1 fusion in a soft tissue sarcoma

Background

RAF family activating fusions have been described as a potentially targetable molecular finding in a subset of soft tissue sarcomas. To further expand upon the landscape of this genetic feature, we describe a novel MTAP-RAF1 activating fusion identified in a S100 positive soft tissue sarcoma.

Case presentation

A 51 year old man underwent excision of a soft tissue mass in his foot. Pathology revealed a spindle cell neoplasm with S100 positivity, ultimately classified as a soft tissue sarcoma, not otherwise specified. Comprehensive molecular profiling was performed to help establish the diagnosis and revealed a novel MTAP-RAF1 fusion that includes the tyrosine kinase domain of RAF1.

Conclusions

Our report adds to the spectrum of fusion-driven RAF activation observed in soft tissue sarcomas and lends additional evidence that RAF activation plays an important role in some soft tissue sarcomas. Identification of novel fusions involving the MAPK/ERK pathway in sarcomas may provide new avenues for precision medicine strategies involving targeted kinase inhibitors.