A multicenter, randomized, non-comparative, phase II study of nivolumab ± ipilimumab for patients with metastatic sarcoma (Alliance A091401): expansion cohorts and correlative analyses

BACKGROUND

In this open-label, randomized, non-comparative, multicenter phase II study (Alliance A091401) we report on three expansion cohorts treated with nivolumab (N) with and without ipilimumab (N+I) and provide a multi-omic correlative analysis of actionable biomarkers.

METHODS

Patients were randomized (non-comparative) to receive either N or N+I. The primary endpoint was a 6-month confirmed response rate (CRR) defined by Response Evaluation Criteria in Solid Tumors version 1.1. Secondary endpoints included treatment-related adverse events (TRAEs), progression-free survival, and overall survival. Multi-omic correlative analyses were conducted using samples from both the primary and expansion cohorts.

RESULTS

A total of 66 patients were evaluated for the primary endpoint with disease including gastrointestinal stromal tumor (GIST, n=18), undifferentiated pleomorphic sarcoma (UPS, n=24), and dedifferentiated liposarcoma (DDLPS, n=24). Neither N nor N+I achieved a complete or partial response in the GIST expansion cohort. In DDLPS and UPS, the primary response endpoint of CRR was met with N+I (both 16.6%, 2/12) but not with N alone (both 8.3%, 1/12). In the GIST cohort, TRAE was higher with N+I treatment, halting enrollment as required per protocol. In a correlative analysis of patients for the expansion cohort and the original cohort (n=86), traditional biomarkers of immunotherapy response were not correlated with response in any histological subtype. Markers of genomic instability including the presence of gene fusions and increased subclonal mutations correlated with improved clinical outcomes.

CONCLUSIONS

This expansion cohort reaffirms the outcomes of A091401. There remains a pressing need to determine the role of and predictive biomarkers for immunotherapy in sarcoma.

TRIAL REGISTRATION NUMBER

NCT02500797.

CSF1R Inhibition in Patients with Advanced Solid Tumors or Tenosynovial Giant Cell Tumor: A Phase I Study of Vimseltinib

PURPOSE

Tenosynovial giant cell tumor (TGCT) is a locally aggressive neoplasm caused by dysregulation of the colony-stimulating factor 1 (CSF1) gene and overexpression of the CSF1 ligand. Surgery is the standard of care for most patients, but there are limited treatment options for patients with TGCT not amenable to surgery. This study evaluates vimseltinib, an investigational, oral, switch-control tyrosine kinase inhibitor designed to selectively and potently inhibit the CSF1 receptor.

PATIENTS AND METHODS

This first-in-human, multicenter, open-label phase I/II study of vimseltinib in patients with malignant solid tumors (N = 37) or TGCT not amenable to surgery (N = 32) followed a pharmacologically guided 3 + 3 study design (NCT03069469). The primary objectives were to assess safety and tolerability, determine the recommended phase II dose, and characterize the pharmacokinetics; exploratory objectives included pharmacodynamics and efficacy.

RESULTS

Vimseltinib was well tolerated; the majority of non-laboratory treatment-emergent adverse events were of grade 1/2 severity. There was no evidence of cholestatic hepatotoxicity or drug-induced liver injury. The recommended phase II dose was determined to be 30 mg twice weekly (no loading dose), and vimseltinib plasma exposure increased with the dose. In patients with TGCT, the median treatment duration was 25.1 months (range, 0.7-46.9), and the objective response rate as assessed by independent radiological review using RECIST version 1.1 was 72%.

CONCLUSIONS

Vimseltinib demonstrated long-term tolerability, manageable safety, dose-dependent exposure, and robust antitumor activity in patients with TGCT not amenable to surgery.

Low-grade fibromyxoid sarcoma and sclerosing epithelioid fibrosarcoma, outcome of advanced disease: retrospective study from the Ultra-Rare Sarcoma Working Group

BACKGROUND

To present findings from a retrospective study conducted by the Ultra-Rare Sarcoma Working Group on metastatic low-grade fibromyxoid sarcoma (LGFMS), sclerosing epithelioid fibrosarcoma (SEF), and hybrid (H)-LGFMS/SEF across 28 global centres.

METHODS

Patients treated at participating institutions from January 2000 to September 2022 were retrospectively selected. Diagnosis was confirmed by expert pathologists. Primary endpoint was progression-free survival (PFS-1) from metastasis detection to first progression or death. PFS-2 was calculated from therapy initiation.

RESULTS

A total of 101 patients were identified (32 LGFMS, 50 SEF, 19 H-LGFMS/SEF). Median (m) follow-up was 62.1 months. mPFS-1 was 28.7, 11.8, and 20.3 months for LGFMS, SEF, and H-LGFMS/SEF, respectively. mOS was 145.8, 41.9, and 113.5 months, respectively. Treatments included anthracycline-based chemotherapy, gemcitabine-based chemotherapy (G), pazopanib, trabectedin, others. mPFS-2 was: 20.1, 5.5, and 3.5 months in H-LGFMS/SEF, SEF, and LGFMS, respectively, with anthracyclines; 19.5, 7.7, and 6.9 months in LGFMS, SEF, and H-LGFMS/SEF, respectively, with pazopanib; 12.0, 9.7, and 3.1 months in H-LGFMS/SEF, LGFMS, and SEF, respectively. Occasional responses occurred with ifosfamide/oral cyclophosphamide, and prolonged stable disease with immune checkpoint inhibitors.

CONCLUSIONS

In this series, the largest available, metastatic LGFMS, SEF, and H-LGFMS/SEF showed different courses. Systemic agents have modest efficacy, informing future trials of novel agents for these tumours.

The Impact of Li Fraumeni and Germline Retinoblastoma Mutations on Leiomyosarcoma Initiation, Outcomes and Genetic Testing Recommendations

PURPOSE

Leiomyosarcomas (LMS) are clinically and molecularly heterogeneous, occurring mostly in sporadic but also syndromic settings. The role of pathogenic germline variants (PGV) as LMS drivers and impact on outcome remain uncertain.

EXPERIMENTAL DESIGN

We perform a comprehensive clinicopathologic and molecular analysis using a tumor-normal DNA next-generation sequencing assay (MSK-IMPACT) of germline-associated LMS compared to sporadic LMS.

RESULTS

Among 285 LMS [120 soft tissue LMS (STLMS), 165 uterine (ULMS)] with germline testing, 78 (27%, 43 STLMS, 35 ULMS) cases harbored PGV: 35/78 (45%) of PGV carriers showing biallelic inactivation of the corresponding gene in the tumor (26 STLMS, 9 ULMS). The most frequent germline predispositions were TP53 (Li-Fraumeni syndrome) (17 patients, 16 in STLMS) and RB1 (retinoblastoma) (13 patients, 11 in STLMS). Germline TP53 and somatic RB1 alterations often co-occurred in the tumor, and vice versa. Other biallelically inactivated PGV were enriched in DNA damage repair-related genes: CHEK2, MSH2, MSH6, RAD51D, BRCA2 and FANCA. Monoallelic PGV were mostly in ULMS and associated with co-occurring TP53 and RB1 somatic alterations. STLMS patients with biallelic but not monoallelic PGV were significantly younger than sporadic STLMS patients (median ages 38 vs 52 vs 58 years). No differences in disease-specific or progression-free survival were observed in germline-associated vs sporadic LMS, regardless of biallelic status.

CONCLUSIONS

While ULMS patients had a relatively low proportion of PGV, a high percentage of STLMS patients with PGV had tumor biallelic status, indicating that PGV drive tumorigenesis in these individuals. These findings have significant implications for genetic testing recommendations.

Interpretable artificial intelligence to optimise use of imatinib after resection in patients with localised gastrointestinal stromal tumours: an observational cohort study

BACKGROUND

Current guidelines recommend use of adjuvant imatinib therapy for many patients with gastrointestinal stromal tumours (GISTs); however, its optimal treatment duration is unknown and some patient groups do not benefit from the therapy. We aimed to apply state-of-the-art, interpretable artificial intelligence (ie, predictions or prescription logic that can be easily understood) methods on real-world data to establish which groups of patients with GISTs should receive adjuvant imatinib, its optimal treatment duration, and the benefits conferred by this therapy.

METHODS

In this observational cohort study, we considered for inclusion all patients who underwent resection of primary, non-metastatic GISTs at the Memorial Sloan Kettering Cancer Center (MSKCC; New York, NY, USA) between Oct 1, 1982, and Dec 31, 2017, and who were classified as intermediate or high risk according to the Armed Forces Institute of Pathology Miettinen criteria and had complete follow-up data with no missing entries. A counterfactual random forest model, which used predictors of recurrence (mitotic count, tumour size, and tumour site) and imatinib duration to infer the probability of recurrence at 7 years for a given patient under each duration of imatinib treatment, was trained in the MSKCC cohort. Optimal policy trees (OPTs), a state-of-the-art interpretable AI-based method, were used to read the counterfactual random forest model by training a decision tree with the counterfactual predictions. The OPT recommendations were externally validated in two cohorts of patients from Poland (the Polish Clinical GIST Registry), who underwent GIST resection between Dec 1, 1981, and Dec 31, 2011, and from Spain (the Spanish Group for Research in Sarcomas), who underwent resection between Oct 1, 1987, and Jan 30, 2011.

FINDINGS

Among 1007 patients who underwent GIST surgery in MSKCC, 117 were included in the internal cohort; for the external cohorts, the Polish cohort comprised 363 patients and the Spanish cohort comprised 239 patients. The OPT did not recommend imatinib for patients with GISTs of gastric origin measuring less than 15·9 cm with a mitotic count of less than 11·5 mitoses per 5 mm2 or for those with small GISTs (<5·4 cm) of any site with a count of less than 11·5 mitoses per 5 mm2. In this cohort, the OPT cutoffs had a sensitivity of 92·7% (95% CI 82·4-98·0) and a specificity of 33·9% (22·3-47·0). The application of these cutoffs in the two external cohorts would have spared 38 (29%) of 131 patients in the Spanish cohort and 44 (35%) of 126 patients in the Polish cohort from unnecessary treatment with imatinib. Meanwhile, the risk of undertreating patients in these cohorts was minimal (sensitivity 95·4% [95% CI 89·5-98·5] in the Spanish cohort and 92·4% [88·3-95·4] in the Polish cohort). The OPT tested 33 different durations of imatinib treatment (<5 years) and found that 5 years of treatment conferred the most benefit.

INTERPRETATION

If the identified patient subgroups were applied in clinical practice, as many as a third of the current cohort of candidates who do not benefit from adjuvant imatinib would be encouraged to not receive imatinib, subsequently avoiding unnecessary toxicity on patients and financial strain on health-care systems. Our finding that 5 years is the optimal duration of imatinib treatment could be the best source of evidence to inform clinical practice until 2028, when a randomised controlled trial with the same aims is expected to report its findings.

FUNDING

National Cancer Institute.

Harmonization of the Upfront Osteosarcoma Treatment Paradigm for Adolescents and Young Adults

Limited guidance exists on streamlining cancer therapy for adolescent and young adult (AYA) patients 15-39 years of age, as much of the current data are extrapolated from pediatric or adult counterparts and can differ significantly between the two care models. Harmonization of standard treatment approaches has the potential to improve outcomes and establish a foundation for the development of future clinical trials. We present our experience harmonizing treatment and supportive care regimens for AYA patients with osteosarcoma receiving treatment with methotrexate, doxorubicin, and cisplatin (MAP) therapy on the pediatric and adult sarcoma services at the Memorial Sloan Kettering Cancer Center.

Vimseltinib versus placebo for tenosynovial giant cell tumour (MOTION): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Tenosynovial giant cell tumour (TGCT) is a locally aggressive neoplasm for which few systemic treatment options exist. This study evaluated the efficacy and safety of vimseltinib, an oral, switch-control, CSF1R inhibitor, in patients with symptomatic TGCT not amenable to surgery.

METHODS

MOTION is a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial done in 35 specialised hospitals in 13 countries. Eligible patients were adults (aged ≥18 years) with a histologically confirmed diagnosis of TGCT for which surgical resection could potentially worsen functional limitation or cause severe morbidity. Patients were randomly assigned (2:1) with interactive response technology to vimseltinib (30 mg orally twice weekly) or placebo, administrated in 28-day cycles for 24 weeks. Patients and site personnel were masked to treatment assignment until week 25, unless progressive disease was confirmed earlier. The primary endpoint was objective response rate by independent radiological review using Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST) at week 25 in the intention-to-treat population. Safety was assessed in all patients who received the study drug. The trial is registered with ClinicalTrials.gov, NCT05059262, and enrolment is complete.

FINDINGS

Between Jan 21, 2022, and Feb 21, 2023, 123 patients were randomly assigned (83 to vimseltinib and 40 to placebo). 73 (59%) patients were female and 50 (41%) were male. Nine (11%) of 83 patients assigned to vimseltinib and five (13%) of 40 patients assigned to placebo discontinued treatment before week 25; one patient in the placebo group did not receive any study drug. Objective response rate per RECIST was 40% (33 of 83 patients) in the vimseltinib group vs 0% (none of 40) in the placebo group (difference 40% [95% CI 29-51]; p<0·0001). Most treatment-emergent adverse events (TEAEs) were grade 1 or 2; the only grade 3 or 4 TEAE that occurred in more than 5% of patients receiving vimseltinib was increased blood creatine phosphokinase (eight [10%] of 83). One patient in the vimseltinib group had a treatment-related serious TEAE of subcutaneous abscess. No evidence of cholestatic hepatotoxicity or drug-induced liver injury was noted.

INTERPRETATION

Vimseltinib produced a significant objective response rate and clinically meaningful functional and symptomatic improvement in patients with TGCT, providing an effective treatment option for these patients.

FUNDING

Deciphera Pharmaceuticals.

Cancer-associated Histone H3 N-terminal arginine mutations disrupt PRC2 activity and impair differentiation

Dysregulated epigenetic states are a hallmark of cancer and often arise from genetic alterations in epigenetic regulators. This includes missense mutations in histones, which, together with associated DNA, form nucleosome core particles. However, the oncogenic mechanisms of most histone mutations are unknown. Here, we demonstrate that cancer-associated histone mutations at arginines in the histone H3 N-terminal tail disrupt repressive chromatin domains, alter gene regulation, and dysregulate differentiation. We find that histone H3R2C and R26C mutants reduce transcriptionally repressive H3K27me3. While H3K27me3 depletion in cells expressing these mutants is exclusively observed on the minor fraction of histone tails harboring the mutations, the same mutants recurrently disrupt broad H3K27me3 domains in the chromatin context, including near developmentally regulated promoters. H3K27me3 loss leads to de-repression of differentiation pathways, with concordant effects between H3R2 and H3R26 mutants despite different proximity to the PRC2 substrate, H3K27. Functionally, H3R26C-expressing mesenchymal progenitor cells and murine embryonic stem cell-derived teratomas demonstrate impaired differentiation. Collectively, these data show that cancer-associated H3 N-terminal arginine mutations reduce PRC2 activity and disrupt chromatin-dependent developmental functions, a cancer-relevant phenotype.

DNA Mutational and Copy Number Variation Profiling of Primary Craniofacial Osteosarcomas by Next-Generation Sequencing

BACKGROUND

Craniofacial osteosarcomas (CFOS) are uncommon malignant neoplasms of the head and neck with different clinical presentation, biological behavior and prognosis from conventional osteosarcomas of long bones. Very limited genetic data have been published on CFOS.

METHODS

In the current study, we performed comprehensive genomic studies in 15 cases of high-grade CFOS by SNP array and targeted next generation sequencing.

RESULT

Our study shows high-grade CFOS demonstrate highly complex and heterogenous genomic alterations and harbor frequently mutated tumor suppressor genes TP53, CDKN2A/B, and PTEN, similar to conventional osteosarcomas. Potentially actionable gene amplifications involving CCNE1, AKT2, MET, NTRK1, PDGFRA, KDR, KIT, MAP3K14, FGFR1, and AURKA were seen in 43% of cases. GNAS hotspot activating mutations were also identified in a subset of CFOS cases, with one case representing malignant transformation from fibrous dysplasia, suggesting a role for GNAS mutation in the development of CFOS.

CONCLUSION

High-grade CFOS demonstrate highly complex and heterogenous genomic alterations, with amplification involving receptor tyrosine kinase genes, and frequent mutations involving tumor suppressor genes.

Best Overall Response-Associated Signature to Doxorubicin in Soft Tissue Sarcomas: A Transcriptomic Analysis from ANNOUNCE

PURPOSE

This exploratory analysis evaluated the tumor samples of the patients treated with doxorubicin (with or without olaratumab) in a negative phase III ANNOUNCE trial to better understand the complexity of advanced soft tissue sarcomas (STS) and to potentially identify its predictive markers.

EXPERIMENTAL DESIGN

RNA sequencing was performed on pretreatment tumor samples (n = 273) from the ANNOUNCE trial to evaluate response patterns and identify potential predictive treatment markers for doxorubicin. A BOR-associated signature to doxorubicin (REDSARC) was created by evaluating tumors with radiographic response versus progression. An external cohort of doxorubicin-treated patients from the Spanish Group for Research on Sarcomas (GEIS) was used for refinement and validation.

RESULTS

A total of 259 samples from the trial were considered for analysis. Comparative analyses by the treatment arm did not explain the negative trial. However, there was an association between the BOR signature and histologic subtype (χ2P = 2.0e-7) and grade (P = 0.002). There were no associations between the BOR signature and gender, age, ethnicity, or stage. Applied to survival outcomes, REDSARC was also predictive for progression-free survival (PFS) and overall survival (OS). Using the GEIS cohort, a refined 25-gene signature was identified and applied to the ANNOUNCE cohort, where it was predictive of PFS and OS in leiomyosarcoma, liposarcoma, and other sarcoma subtypes, but not in undifferentiated pleomorphic sarcoma.

CONCLUSIONS

The refined REDSARC signature provides a potential tool to direct the application of doxorubicin in sarcomas and other malignancies. Validation and further refinement of the signature in other potentially subtype specific prospective cohorts is recommended.

Developing Novel Genomic Risk Stratification Models in Soft Tissue and Uterine Leiomyosarcoma

PURPOSE

Leiomyosarcomas (LMS) are clinically and molecularly heterogeneous tumors. Despite recent large-scale genomic studies, current LMS risk stratification is not informed by molecular alterations. We propose a clinically applicable genomic risk stratification model.

EXPERIMENTAL DESIGN

We performed comprehensive genomic profiling in a cohort of 195 soft tissue LMS (STLMS), 151 primary at presentation, and a control group of 238 uterine LMS (ULMS), 177 primary at presentation, with at least 1-year follow-up.

RESULTS

In STLMS, French Federation of Cancer Centers (FNCLCC) grade but not tumor size predicted progression-free survival (PFS) or disease-specific survival (DSS). In contrast, in ULMS, tumor size, mitotic rate, and necrosis were associated with inferior PFS and DSS. In STLMS, a 3-tier genomic risk stratification performed well for DSS: high risk: co-occurrence of RB1 mutation and chr12q deletion (del12q)/ATRX mutation; intermediate risk: presence of RB1 mutation, ATRX mutation, or del12q; low risk: lack of any of these three alterations. The ability of RB1 and ATRX alterations to stratify STLMS was validated in an external AACR GENIE cohort. In ULMS, a 3-tier genomic risk stratification was significant for both PFS and DSS: high risk: concurrent TP53 mutation and chr20q amplification/ATRX mutations; intermediate risk: presence of TP53 mutation, ATRX mutation, or amp20q; low risk: lack of any of these three alterations. Longitudinal sequencing showed that most molecular alterations were early clonal events that persisted during disease progression.

CONCLUSIONS

Compared with traditional clinicopathologic models, genomic risk stratification demonstrates superior prediction of clinical outcome in STLMS and is comparable in ULMS.

Chromoplexy Is a Frequent Early Clonal Event in EWSR1-Rearranged Round Cell Sarcomas That Can Be Detected Using Clinically Validated Targeted Sequencing Panels

Chromoplexy is a phenomenon defined by large-scale chromosomal chained rearrangements. A previous study observed chromoplectic events in a subset of Ewing sarcomas (ES), which was linked to an increased relapse rate. Chromoplexy analysis could potentially facilitate patient risk stratification, particularly if it could be detected with clinically applied targeted next-generation sequencing (NGS) panels. Using DELLY, a structural variant (SV) calling algorithm that is part of the MSK-IMPACT pipeline, we characterized the spectrum of SVs in EWSR1-fused round cell sarcomas, including 173 ES and 104 desmoplastic small round cell tumors (DSRCT), to detect chromoplexy and evaluate its association with clinical and genomic features. Chromoplectic events were detected in 31% of the ES cases and 19% of the DSRCT cases. EWSR1 involvement accounted for 76% to 93% of these events, being rearranged with diverse noncanonical gene partners across the genome, involving mainly translocations but also intrachromosomal deletions and inversions. A major breakpoint cluster was located on EWSR1 exons 8-13. In a subset of cases, the SVs disrupted adjacent loci, forming deletion bridges. Longitudinal sequencing and breakpoint allele fraction analysis showed that chromoplexy is an early event that remains detectable throughout disease progression and likely develops simultaneously with the driver fusion. The presence of chromoplexy was validated in an external ES patient cohort with whole exome sequencing. Chromoplexy was significantly more likely to be present in cases that were metastatic at presentation. Together, this study identifies chromoplexy as a frequent genomic alteration in diverse EWSR1-rearranged tumors that can be captured by targeted NGS panels.

SIGNIFICANCE

Chromoplexy is detectable using targeted NGS in a substantial portion of EWSR1-rearranged round cell sarcomas as an early and persistent clonal event, expanding the genomic complexity of fusion-associated sarcomas.

Challenges and Solutions to Support Oncology Professionals Serving Underserved Populations With Cancer in the United States: Results From the ASCO Serving the Underserved Task Force

PURPOSE

Little data exist regarding approaches to support oncology professionals who deliver cancer care for underserved populations. In response, ASCO developed the Serving the Underserved Task Force to learn from and support oncology professionals serving underserved populations.

METHODS

The Task Force developed a 28-question survey to assess oncology professionals' experiences and strategies to support their work caring for underserved populations. The survey was deployed via an online link to 600 oncology professionals and assessed respondent and patient demographic characteristics, clinic-based processes to coordinate health-related social services, and strategies for professional society support and engagement. We used chi-square tests to evaluate whether there were associations between percent full-time equivalent (FTE) effort serving underserved populations (<50% FTE v ≥50% FTE) with responses.

RESULTS

Of 462 respondents who completed the survey (77% response rate), 79 (17.1%) were Asian; 30 (6.5%) Black; 43 (9.3%) Hispanic or Latino/Latina; and 277 (60%) White. The majority (n = 366, 79.2%) had a medical doctor degree (MD). A total of 174 (37.7%) had <25% FTE, 151 (32.7%) had 25%-50% FTE, and 121 (26.2%) had ≥50% FTE effort serving underserved populations. Most best guessed patients' sociodemographic characteristics (n = 388; 84%), while 42 (9.2%) used data collected by the clinic. Social workers coordinated most health-related social services. However, in clinical settings with high proportions of underserved patients, there was greater reliance on nonclinical personnel, such as navigators (odds ratio [OR], 2.15 [95% CI, 1.07 to 4.33]) or no individual (OR, 2.55 [95% CI, 1.14 to 5.72]) for addressing mental health needs and greater reliance on physicians or advance practice practitioners (OR, 2.54 [95% CI, 1.11 to 5.81]) or no individual (OR, 1.91 [95% CI, 1.09 to 3.35]) for addressing childcare or eldercare needs compared with social workers. Prioritization of solutions, which did not differ by FTE effort serving underserved populations, included a return-on-investment model to support personnel, integrated health-related social needs screening, and collaboration with the professional society on advocacy and policy.

CONCLUSION

The findings highlight crucial strategies that professional societies can implement to support oncology clinicians serving underserved populations with cancer.

A call to action to advance patient-focused and decentralized clinical trials

This commentary is a call to action for a concerted commitment and effort to transform clinical trials and enable people with cancer to participate in clinical trials closer to home. Three key strategies are identified to address major barriers: confront challenges with the interpretation of US Food and Drug Administration Form 1572 requirements (Statement of Investigator); broaden acceptance of local laboratories and imaging centers; and invest in the creation of effective, sustainable partnerships between research centers and local providers.

Afamitresgene autoleucel for advanced synovial sarcoma and myxoid round cell liposarcoma (SPEARHEAD-1): an international, open-label, phase 2 trial

BACKGROUND

Afamitresgene autoleucel (afami-cel) showed acceptable safety and promising efficacy in a phase 1 trial (NCT03132922). The aim of this study was to further evaluate the efficacy of afami-cel for the treatment of patients with HLA-A*02 and MAGE-A4-expressing advanced synovial sarcoma or myxoid round cell liposarcoma.

METHODS

SPEARHEAD-1 was an open-label, non-randomised, phase 2 trial done across 23 sites in Canada, the USA, and Europe. The trial included three cohorts, of which the main investigational cohort (cohort 1) is reported here. Cohort 1 included patients with HLA-A*02, aged 16-75 years, with metastatic or unresectable synovial sarcoma or myxoid round cell liposarcoma (confirmed by cytogenetics) expressing MAGE-A4, and who had received at least one previous line of anthracycline-containing or ifosfamide-containing chemotherapy. Patients received a single intravenous dose of afami-cel (transduced dose range 1·0 × 109-10·0 × 109 T cells) after lymphodepletion. The primary endpoint was overall response rate in cohort 1, assessed by a masked independent review committee using Response Evaluation Criteria in Solid Tumours (version 1.1) in the modified intention-to-treat population (all patients who received afami-cel). Adverse events, including those of special interest (cytokine release syndrome, prolonged cytopenia, and neurotoxicity), were monitored and are reported for the modified intention-to-treat population. This trial is registered at ClinicalTrials.gov, NCT04044768; recruitment is closed and follow-up is ongoing for cohorts 1 and 2, and recruitment is open for cohort 3.

FINDINGS

Between Dec 17, 2019, and July 27, 2021, 52 patients with cytogenetically confirmed synovial sarcoma (n=44) and myxoid round cell liposarcoma (n=8) were enrolled and received afami-cel in cohort 1. Patients were heavily pre-treated (median three [IQR two to four] previous lines of systemic therapy). Median follow-up time was 32·6 months (IQR 29·4-36·1). Overall response rate was 37% (19 of 52; 95% CI 24-51) overall, 39% (17 of 44; 24-55) for patients with synovial sarcoma, and 25% (two of eight; 3-65) for patients with myxoid round cell liposarcoma. Cytokine release syndrome occurred in 37 (71%) of 52 of patients (one grade 3 event). Cytopenias were the most common grade 3 or worse adverse events (lymphopenia in 50 [96%], neutropenia 44 [85%], leukopenia 42 [81%] of 52 patients). No treatment-related deaths occurred.

INTERPRETATION

Afami-cel treatment resulted in durable responses in heavily pre-treated patients with HLA-A*02 and MAGE-A4-expressing synovial sarcoma. This study shows that T-cell receptor therapy can be used to effectively target solid tumours and provides rationale to expand this approach to other solid malignancies.

FUNDING

Adaptimmune.

Sarcoma microenvironment cell states and ecosystems are associated with prognosis and predict response to immunotherapy

Characterization of the diverse malignant and stromal cell states that make up soft tissue sarcomas and their correlation with patient outcomes has proven difficult using fixed clinical specimens. Here, we employed EcoTyper, a machine-learning framework, to identify the fundamental cell states and cellular ecosystems that make up sarcomas on a large scale using bulk transcriptomes with clinical annotations. We identified and validated 23 sarcoma-specific, transcriptionally defined cell states, many of which were highly prognostic of patient outcomes across independent datasets. We discovered three conserved cellular communities or ecotypes associated with underlying genomic alterations and distinct clinical outcomes. We show that one ecotype defined by tumor-associated macrophages and epithelial-like malignant cells predicts response to immune-checkpoint inhibition but not chemotherapy and validate our findings in an independent cohort. Our results may enable identification of patients with soft tissue sarcomas who could benefit from immunotherapy and help develop new therapeutic strategies.

The MOTION study: a randomized, phase III study of vimseltinib for the treatment of tenosynovial giant cell tumor

Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive neoplasm that occurs in the synovium of joints, bursae, or tendon sheaths and is caused by upregulation of the CSF1 gene. Vimseltinib is an oral switch-control tyrosine kinase inhibitor specifically designed to selectively and potently inhibit the CSF1 receptor. Here, we describe the rationale and design for the phase III MOTION trial (NCT05059262), which aims to evaluate the efficacy and safety of vimseltinib in participants with TGCT not amenable to surgical resection. In part 1, participants are randomized to receive vimseltinib 30 mg twice weekly or matching placebo for ≤24 weeks. Part 2 is a long-term treatment phase in which participants will receive open-label vimseltinib.

The patient perspective on sirolimus for epithelioid hemangioendothelioma (EHE): results of a community survey highlighting the importance of equitable access to treatments

Background

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, vascular sarcoma with clinical presentation ranging from an indolent to an aggressive form. Over 50% of patients present with metastatic disease, requiring systemic therapy, although no systemic therapies are specifically approved for EHE. Retrospective evidence supports the activity of mTOR inhibitors (e.g. sirolimus), although available only off-label. EHE patients and advocates are therefore working to support approval of effective treatments by collecting data on patient perspectives and experiences.

Materials and methods

In February 2023, the EHE Rare Cancer Charity (UK) and The EHE Foundation (US), with other advocates, conducted a survey of perspectives and experiences of EHE patients regarding the use and accessibility of sirolimus. The survey consisted of 20 questions designed for individuals undergoing treatment, those who had been treated, or had never been treated with the drug. Widely promoted within the patient community, the online survey categorized patients into three cohorts for the analysis: liver transplant patients, non-transplant patients who had ever taken sirolimus and sirolimus-naïve non-transplant patients.

Results

The survey evaluated data from 129 patient responses from 21 countries, mostly from USA, UK, Australia, and Canada (70%). The liver transplant, sirolimus and non-sirolimus cohorts were 16%, 25% and 59%, respectively. In the sirolimus group 66% reported treatment durations exceeding one year, with 16% exceeding five years, indicating the drug's efficacy. In the non-sirolimus group, the drug was not available for 42% and for 11% sirolimus was available but not selected for treatment because of its off-label status. Overall, 87% of all patients across all cohorts expressed the importance of the drug's availability as hugely or very important.

Conclusion

The survey responses highlight the activity of sirolimus for EHE and the importance of securing a label extension for the drug delivering equitable access to this treatment for patients.

Therapy-Induced Senescence Contributes to the Efficacy of Abemaciclib in Patients with Dedifferentiated Liposarcoma

PURPOSE

We conducted research on CDK4/6 inhibitors (CDK4/6i) simultaneously in the preclinical and clinical spaces to gain a deeper understanding of how senescence influences tumor growth in humans.

PATIENTS AND METHODS

We coordinated a first-in-kind phase II clinical trial of the CDK4/6i abemaciclib for patients with progressive dedifferentiated liposarcoma (DDLS) with cellular studies interrogating the molecular basis of geroconversion.

RESULTS

Thirty patients with progressing DDLS enrolled and were treated with 200 mg of abemaciclib twice daily. The median progression-free survival was 33 weeks at the time of the data lock, with 23 of 30 progression-free at 12 weeks (76.7%, two-sided 95% CI, 57.7%-90.1%). No new safety signals were identified. Concurrent preclinical work in liposarcoma cell lines identified ANGPTL4 as a necessary late regulator of geroconversion, the pathway from reversible cell-cycle exit to a stably arrested inflammation-provoking senescent cell. Using this insight, we were able to identify patients in which abemaciclib induced tumor cell senescence. Senescence correlated with increased leukocyte infiltration, primarily CD4-positive cells, within a month of therapy. However, those individuals with both senescence and increased TILs were also more likely to acquire resistance later in therapy. These suggest that combining senolytics with abemaciclib in a subset of patients may improve the duration of response.

CONCLUSIONS

Abemaciclib was well tolerated and showed promising activity in DDLS. The discovery of ANGPTL4 as a late regulator of geroconversion helped to define how CDK4/6i-induced cellular senescence modulates the immune tumor microenvironment and contributes to both positive and negative clinical outcomes. See related commentary by Weiss et al., p. 649.

Incremental Utility of First-Pass Perfusion CMR for Prognostic Risk Stratification of Cancer-Associated Cardiac Masses

BACKGROUND

Cardiac magnetic resonance (CMR) differentiates cardiac metastasis (CMET) and cardiac thrombus (CTHR) based on tissue characteristics stemming from vascularity on late gadolinium enhancement (LGE). Perfusion CMR can assess magnitude of vascularity; utility for cardiac masses (CMASS) is unknown.

OBJECTIVES

This study sought to determine if perfusion CMR provides diagnostic and prognostic utility for CMASS beyond binary differentiation of CMET and CTHR.

METHODS

The population comprised adult cancer patients with CMASS on CMR; CMET and CTHR were defined using LGE-CMR: CMASS+ patients were matched to CMASS- control subjects for cancer type/stage. First-pass perfusion CMR was interpreted visually and semiquantitatively for CMASS vascularity, including contrast enhancement ratio (CER) (plateau vs baseline) and contrast uptake rate (CUR) (slope). Follow-up was performed for all-cause mortality.

RESULTS

A total of 462 cancer patients were studied, including patients with (CMET = 173, CTHR = 69) and without CMASS on LGE-CMR. On perfusion CMR, CER and CUR were higher within CMET vs CTHR (P < 0.001); CUR yielded better performance (AUC: 0.89-0.93) than CER (AUC: 0.66-0.72) (both P < 0.001) to differentiate LGE-CMR-evidenced CMET and CTHR, although both CUR (P = 0.10) and CER (P = 0.01) typically misclassified CMET with minimal enhancement. During follow-up, mortality among CMET patients was high but variable; 47% of patients were alive 1 year post-CMR. Patients with semiquantitative perfusion CMR-evidenced CMET had higher mortality than control subjects (HR: 1.42 [95% CI: 1.06-1.90]; P = 0.02), paralleling visual perfusion CMR (HR: 1.47 [95% CI: 1.12-1.94]; P = 0.006) and LGE-CMR (HR: 1.52 [95% CI: 1.16-2.00]; P = 0.003). Among patients with CMET on LGE-CMR, mortality was highest among patients (P = 0.002) with lesions in the bottom perfusion (CER) tertile, corresponding to low vascularity. Among CMET and cancer-matched control subjects, mortality was equivalent (P = NS) among patients with lesions in the upper CER tertile (corresponding to higher lesion vascularity). Conversely, patients with CMET in the middle (P = 0.03) and lowest (lowest vascularity) (P = 0.001) CER tertiles had increased mortality.

CONCLUSIONS

Perfusion CMR yields prognostic utility that complements LGE-CMR: Among cancer patients with LGE-CMR defined CMET, mortality increases in proportion to magnitude of lesion hypoperfusion.

Subclonal Somatic Copy-Number Alterations Emerge and Dominate in Recurrent Osteosarcoma

Multiple large-scale genomic profiling efforts have been undertaken in osteosarcoma to define the genomic drivers of tumorigenesis, therapeutic response, and disease recurrence. The spatial and temporal intratumor heterogeneity could also play a role in promoting tumor growth and treatment resistance. We conducted longitudinal whole-genome sequencing of 37 tumor samples from 8 patients with relapsed or refractory osteosarcoma. Each patient had at least one sample from a primary site and a metastatic or relapse site. Subclonal copy-number alterations were identified in all patients except one. In 5 patients, subclones from the primary tumor emerged and dominated at subsequent relapses. MYC gain/amplification was enriched in the treatment-resistant clones in 6 of 7 patients with multiple clones. Amplifications in other potential driver genes, such as CCNE1, RAD21, VEGFA, and IGF1R, were also observed in the resistant copy-number clones. A chromosomal duplication timing analysis revealed that complex genomic rearrangements typically occurred prior to diagnosis, supporting a macroevolutionary model of evolution, where a large number of genomic aberrations are acquired over a short period of time followed by clonal selection, as opposed to ongoing evolution. A mutational signature analysis of recurrent tumors revealed that homologous repair deficiency (HRD)-related SBS3 increases at each time point in patients with recurrent disease, suggesting that HRD continues to be an active mutagenic process after diagnosis. Overall, by examining the clonal relationships between temporally and spatially separated samples from patients with relapsed/refractory osteosarcoma, this study sheds light on the intratumor heterogeneity and potential drivers of treatment resistance in this disease.

SIGNIFICANCE

The chemoresistant population in recurrent osteosarcoma is subclonal at diagnosis, emerges at the time of primary resection due to selective pressure from neoadjuvant chemotherapy, and is characterized by unique oncogenic amplifications.

Immune-related Adverse Events after Immune Checkpoint Blockade-based Therapy Are Associated with Improved Survival in Advanced Sarcomas

The association between immune-related AEs (irAE) and outcome in patients with sarcoma is not known. We retrospectively reviewed a cohort of patients with advanced sarcoma treated with immune checkpoint blockade (ICB)-based therapy. Association of irAEs with survival was assessed using a Cox regression model that incorporated irAE occurrence as a time-dependent covariate. Tumor samples with available RNA sequencing data were stratified by presence of an irAE to identify patterns of differential gene expression. A total of 131 patients were included. Forty-two (32%) had at least one irAE of any grade and 16 (12%) had at least one grade ≥ 3 irAE. The most common irAEs were hypothyroidism (8.3%), arthralgias (5.3%), pneumonitis (4.6%), allergic reaction (3.8%), and elevated transaminases (3.8%). Median progression-free survival (PFS) and overall survival (OS) from the time of study entry were 11.4 [95% confidence interval (CI), 10.7-15.0) and 74.6 weeks (CI, 44.9-89.7), respectively. On Cox analysis adjusting for clinical covariates that were significant in the univariate setting, the HR for an irAE (HR, 0.662; CI, 0.421-1.041) approached, but did not reach statistical significance for PFS (P = 0.074). Patients had a significantly lower HR for OS (HR, 0.443; CI, 0.246-0.798; P = 0.007) compared with those without or before an irAE. Gene expression profiling on baseline tumor samples found that patients who had an irAE had higher numbers of tumor-infiltrating dendritic cells, CD8+ T cells, and regulatory T cells as well as upregulation of immune and inflammatory pathways.

SIGNIFICANCE

irAE after ICB therapy was associated with an improved OS; it also approached statistical significance for improved PFS. Patients who had an irAE were more likely to have an inflamed tumor microenvironment at baseline.

Novel Genomic Risk Stratification Model for Primary Gastrointestinal Stromal Tumors (GIST) in the Adjuvant Therapy Era

PURPOSE

Traditional risk stratification schemes in gastrointestinal stromal tumors (GIST) were defined in the pre-imatinib era and rely solely on clinicopathologic metrics. We hypothesize that genomic-based risk stratification is prognostically relevant in the current era of tyrosine kinase inhibitor (TKI) therapeutics.

EXPERIMENTAL DESIGN

Comprehensive mutational and copy-number profiling using MSK-IMPACT was performed. We integrated clinicopathologic and genomic parameters and utilized an elastic-net penalized Cox proportional hazards machine learning model for outcome risk stratification.

RESULTS

A 3-tier genomic risk stratification model for recurrence-free survival (RFS) in 152 primary localized gastric and 80 small bowel GISTs was proposed. Gastric GISTs were classified as high risk if chr1p deletion or SDHB loss was present, and intermediate risk if chr14q deletion was present or KIT exon 11 mutation was absent. Small bowel GISTs were classified as high risk if MAX/MGA/MYC, CDKN2A, or RB1 alterations were present, and intermediate risk if chr1p deletion or chr5q amplification was present. Compared with conventional risk stratification, genomic risk stratification both upgrades and downgrades, suggesting that conventional risk stratification may underestimate or overtreat some high-risk and low-risk patients, respectively. Longitudinal sequencing detected most KIT-independent genomic alterations at baseline. Subanalysis in 26 SDH-deficient GISTs revealed that presence of TP53 mutations or chr1q amplifications portends worse RFS and disease-free survival.

CONCLUSIONS

We developed a novel, next-generation genomic risk stratification model for primary gastric and small bowel GISTs, complementing traditional clinicopathologic models. Future independent validation of our model in external cohorts is essential.