Selinexor for the treatment of recurrent or metastatic salivary gland tumors: Results from the GEMS-001 clinical trial

OBJECTIVES

We aimed to evaluate the activity of selinexor, an oral selective inhibitor of nuclear export, in patients with recurrent or metastatic salivary gland tumors (SGT).

METHODS

GEMS-001 is an open-label Phase 2 study for patients with recurrent or metastatic SGT with two parts. In Part 1 of the protocol, patients had tumor samples profiled with targeted next generation sequencing as well as immunohistochemistry for androgen receptor, HER-2 and ALK. For Part 2, patients with no targeted therapies available were eligible to receive selinexor 60 mg given twice weekly every 28 days. The primary endpoint was objective response rate. Secondary endpoints included progression-free survival (PFS) and prevalence of druggable alterations across SGT.

RESULTS

One hundred patients were enrolled in GEMS-001 and underwent genomic and immunohistochemistry profiling. A total of 21 patients who lacked available matched therapies were treated with selinexor. SGT subtypes (WHO classification) included adenoid cystic carcinoma (n = 10), salivary duct carcinoma (n = 3), acinic cell carcinoma (n = 2), myoepithelial carcinoma (n = 2), carcinoma ex pleomorphic adenoma (n = 2) and other (n = 2). Of 18 evaluable patients, stable disease (SD) was observed in 17 patients (94%) (SD ≥6 months in 7 patients (39%)). However, no objective responses were observed. The median PFS was 4.9 months (95% confidence interval, 3.4-10). The most common treatment-related Grade 1-2 adverse events were nausea [17 patients (81%)], fatigue [16 patients (76%)], and dysgeusia [12 patients (57%)]. Most common treatment-related Grade 3-4 adverse events were hyponatremia [3 patients (14%)], neutrophil count decrease [3 patients (14%)] and cataracts [2 patients (10%)]. No treatment-related deaths were observed.

CONCLUSIONS

Although tumor reduction was observed across participants, single agent selinexor anti-tumor activity was limited.

Abstract P154: Genomic profiling and matched therapy for recurrent or metastatic salivary gland neoplasms. Results from the matched cohort of the GEMS-001 clinical trial

Background Salivary gland tumors (SGT) are rare and heterogeneous diseases with limited systemic options available. Results from recent basket trials including SGT cohorts for specific actionable alterations (AA) have described promising outcomes with molecularly targeted approaches (TA). Methods The GEMS-001 study (NCT02069730) is an ongoing multi-arm trial with two phases. In part 1, recurrent or metastatic (R/M) SGT patients (pts) undergo comprehensive immunohistochemistry (IHC) including HER2, androgen receptor (AR) and ALK translocation and multigene panel testing (NGS). Based on the molecular profiling results in part 1, R/M SGT pts are matched to available targeted therapies on disease progression. Here, we present the efficacy results for the matched cohort of the GEMS-001 study. Results As of July 2021, 100 pts underwent molecular profiling within part 1. According to the SGT subtype (WHO 2017): 49% adenoid cystic carcinoma (ACC), 18% salivary duct carcinoma (SDC), 9% acinic (ACI) and 24% other subtypes (O). Overall, on IHC HER2 overexpression was present in 10%, AR 24% and ALK translocation 0%. On NGS, PIK3CA mutation (mut) was in 10%, HRAS mut 7%, ERBB2/3 alterations (alt) 5%, NOTCH1-3 mut 2% and ETV6-NTRK3 fusion 2%. Up to 45% pts displayed at least 1 AA and 25% had ≥2 AA. AA were enriched in SDC (100% ≥1 AA) as compared to ACI (33% ≥1 AAs), O (58% ≥1 AA) or ACC (22% ≥1 AA) (p<0.001 Fisher's exact test). A total of 34 pts (34%) were matched to proteomic or genomic alterations. Of those matched, median age was 62 years (range 47-84), M:F 26:8, 100% ECOG≤1, and their AA-TA included 15 AR (leuprolide+bicalutamide), 4 HER2 or ERBB2 alt (trastuzumab+pertuzumab), 4 PIK3CA mut (PIK3CA inhibitor), 2 cyclin pathway alt (palbociclib), 2 ETV6-NTRK3 fusion (larotrectinib) and 7 other AAs (1 EGFR L858 mut (afatinib), 1 c-KIT mut (imatinib), 1 BAP1 mut (olaparib), 1 Non-V600 BRAF mut (pan-RAF inhibitor), 1 CHEK2 mut (olaparib), 1 ATM mut (olaparib) and 1 PTCH1 (vismodegib)). As per efficacy, overall response rate was 24% and median progression free survival 6.4 months (m) (95%CI 3.4-8.9 m) for the matched population. Complete responses were observed in 2 pts treated with leuprolide+biculatamide (AR). Partial responses were observed in 2 pts treated with larotrectinib (ETV6-NTRK3), 3 pts treated with trastuzumab+pertuzumab (HER2) and 1 pt treated with leuprolide+biculatamide (AR). Notably, among responders median duration of response was 13.9 m (95%CI 4.6-18.0 m). Conclusions In our cohort, more than one third of the population were matched to TA with promising efficacy outcomes. Our results support comprehensive molecular and IHC profiling but its clinical utility may vary depending on the SGT subtype.

Citation Format: Alberto Hernando-Calvo, Eoghan Malone, Daphne Dai, Amy Prawira, Ilan Weinreb, Anneli Eliason, Angela Rodriguez, Katherine Lajkosz, Sarah Jennings, Anna Spreafico, Lillian L. Siu, Aaron Hansen. Genomic profiling and matched therapy for recurrent or metastatic salivary gland neoplasms. Results from the matched cohort of the GEMS-001 clinical trial [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P154.

Prospective manipulation of the gut microbiome with Microbial Ecosystem Therapeutic 4 (MET4) in locoregionally advanced oropharyngeal squamous cell carcinoma (LA-OPSCC) undergoing primary chemoradiation (ROMA2)

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Background: Therapeutic manipulation of the gut microbiome in cancer patients (pts) is an area of active investigation. MET4 (NuBiyota) is an oral alternative to fecal transplant consisting of a mixture of human gut bacteria associated with immunotherapy (IO) response. We previously reported variation in IO-responsive taxa across stages in human papilloma virus related (HPV+) LA-OPSCC pts treated with chemoradiotherapy (CRT) (Oliva et al., ASCO 2020). ROMA-2 is the first interventional study evaluating the safety, feasibility and ecological effect of MET4, in combination with definitive CRT in HPV+ LA-OPSCC (NCT03838601). Methods: This is an investigator-initiated study of pts with HPV+ LA-OPSCC treated with standard of care CRT. MET4 is administered daily until week 4 of CRT or unacceptable toxicity. Stool samples are collected at baseline, week 4, week 8-10, and 2-months post CRT. Bacterial V4 16S rDNA was extracted from stool and sequenced. Microbiome analyses were conducted in R using DADA2, phyloseq and DESeq2. Results: As of February 11 2021, 25 pts have been enrolled. A total of 50 stool samples from the first 14 pts were collected (98% adherence) and analyzed. Baseline cohort characteristics: median age = 62.5 (range, 48-69); Stage I/II/III = 5/1/8; use of antibiotics = 1pt. 3 pts did not complete the 3-week course of MET4 treatment due to non-compliance (n = 1), withdrawal of consent (n = 1) and grade 2 diarrhea (n = 1). Other reported MET4-related adverse events (all grade 1) included bloating (n = 2), flatulence (n = 1) and belching (n = 1). No longitudinal changes in alpha-diversity were seen from baseline through follow up. Administration of MET4 resulted in a transient trend towards increased cumulative MET4 taxa relative abundance (RA) by week 4. Stage III patients demonstrated the lowest MET4 taxa RA at baseline, and the greatest increase in MET4 taxa RA from baseline to week 4. By week 4 the following taxa in all pts were increased compared to baseline: Eubacterium hallii (21.71 Log2Fold change[L2FC], padj < 0.001) and Parabacteroides johnsonii (23.67 L2FC, padj < 0.001). An increase in the following taxa was observed by weeks 8-10 compared to baseline: Akkermansia muciniphilla (3.75 L2FC, padj = 0.027), Bacteroides fragilis (6.73 L2FC, padj = 0.010), Alistipes onderdonkii (3.30 L2FC, padj = 0.049) and Parabacteroides distasonis (24.43 L2FC, padj < 0.001). Conclusions: Manipulation of the gut microbiota in these pts was feasible and safe. MET4-induced ecological changes are heterogenous and vary by taxa. MET4 taxa implicated in IO-response were increased by week 4 and week 8-10. This increase was higher in pts with stage III disease. These data suggest that specific subgroups may benefit from combination IO therapy and may guide pt selection for further interventional clinical trial design. Clinical trial information: NCT03838601.

Molecular profiling and targeted agents in recurrent, metastatic salivary gland tumor (R/M SGT) patients (pts) treated at two academic centers

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Background: Treatment selection based on actionable alterations (AAs) is an appealing strategy for pts with R/M SGT. The GEMS-001 study (NCT02069730) at Princess Margaret Cancer Centre (PM) and the Vall D´Hebron Institute of Oncology (VHIO) pre-screening program facilitate the identification of AAs for R/M SGT pts and treatment selection. Methods: We analyzed R/M SGT treated at PM and VHIO from 2015 to 2020. Clinicopathological features, molecular alterations and treatment modalities were correlated with outcomes. The primary endpoint was overall response rate (ORR) by RECIST 1.1. Clinical benefit rate (CBR) was defined by pts with partial response or stable disease ≥4 months. Clinical actionability of multigene panel testing (NGS) and immunohistochemistry (IHC) were assessed as per institutional molecular tumor boards or investigators. Pts were opportunistically matched to available therapies from each center. Results: In total 206 pts were enrolled. On IHC, HER2 overexpression was present in 9%, Androgen Receptor (AR) 33%, Estrogen/Progesterone Receptor (ER/PR) 11% and ALK overexpression 0%. On NGS, PIK3CA mutation (mut) was in 9%, NTRK fusion 6%, NOTCH1-3 mut 5%, HRAS mut 6%, ERBB2/3 alterations (alt) 4% and FGFR1-4 alt 3%. Up to 92 pts (45%) displayed at least 1 AA and 36 pts (18%) had ≥2 AAs. A total of 60 pts (29%) were matched to AAs. Of those matched, median age was 60 years (range 33-84), M:F 21:39, 95% ECOG≤1 with a median number of prior treatment lines 0 (range 0-3), and their AAs included 26 AR, 9 HER2 or ERBB2 overexpression, 9 PIK3CA mut, 3 NTRK fusion, 3 FGFR1-3 alt and 10 other AAs (2 ER/PR overexpression, 2 EGFR mut, 1 c-kit mut, 1 BAP1 mut, 1 Non-V600 BRAF mut, 1 CDKN2A mut, 1 CHEK2 mut and 1 PTCH1 mut). Overall, ORR was 27% for the matched population. See table for outcomes. Conclusions: In our cohort, almost one third of the population received therapies matched to AAs. Our results suggest that targeted therapies have promising activity in pts with R/M SGT supporting comprehensive molecular and IHC profiling in treatment determination.[Table: see text]