Phase 1b study of batiraxcept in combination with durvalumab in patients with platinum-resistant ovarian cancer

Combining an immune checkpoint inhibitor with batiraxcept (AVB-S6-500), an AXL inhibitor that acts via selective binding to growth arrest-specific protein 6 (GAS6), may improve anti-tumor immunity in platinum-resistant ovarian cancer (PROC). This phase 1b trial of durvalumab in combination with escalating doses of batiraxcept enrolled patients with recurrent PROC (NCT04019288). The primary objective was to determine the toxicity profile of the combination. Eleven patients were enrolled on the trial. No dose-limiting toxicities were observed, and no objective responses were noted. Median progression free survival (PFS) was 1.81 months (95% confidence interval (CI) 1.71-2.40), and median overall survival (OS) was 4.53 months (95% CI 2.10-24.74). Batiraxcept effectively reduced serum GAS6 levels at 1-h post-treatment, resulting in trough levels below the limit of detection in all cases but one. In conclusion, the combination of batiraxcept and durvalumab was safe and tolerable but did not demonstrate anti-tumor activity in a heterogenous population of patients with recurrent PROC.

Clinical and genomic landscape of RAS mutations in gynecologic cancers

BACKGROUND

We aimed to describe RAS mutations in gynecologic cancers as they relate to clinicopathologic and genomic features, survival, and therapeutic implications.

METHODS

Gynecologic cancers with available somatic molecular profiling data at our institution between February 2010 and August 2022 were included and grouped by RAS mutation status. Overall survival was estimated by Kaplan-Meier method, and multivariable analysis was performed using Cox proportional-hazards model.

RESULTS

Of 3328 gynecologic cancers, 523 (15.7%) showed any RAS mutation. Patients with RAS-mutated tumors were younger (57 vs 60 years non-mutated), had higher prevalence of endometriosis (27.3% vs 16.9%), and lower grades (grade 1/2, 43.2% vs 8.1%, all p<0.0001). Highest prevalence of KRAS mutation was in mesonephric-like endometrial (100%, n=9/9), mesonephric-like ovarian (83.3%, n=5/6), mucinous ovarian (60.4%), and low-grade serous ovarian (44.4%) cancers. After adjustment for age, cancer type, and grade, RAS mutation was associated with worse overall survival (HR=1.3, p=0.001). Specific mutations were in KRAS (13.5%), NRAS (2.0%), and HRAS (0.51%), most commonly KRAS G12D (28.4%) and G12V (26.1%). Common co-mutations were PIK3CA (30.9%), PTEN(28.8%), ARID1A (28.0%), and TP53 (27.9%), of which 64.7% were actionable. RAS+MAPK pathway-targeted therapies were administered to 62 patients with RAS-mutated cancers. While overall survival was significantly higher with therapy (8.4 years [95%CI 5.5-12.0] vs 5.5 years [95%CI 4.6-6.6], HR=0.67, p=0.031), this effect did not persist in multivariable analysis.

CONCLUSION

RAS mutations in gynecologic cancers have a distinct histopathologic distribution and may impact overall survival. PIK3CA, PTEN, and ARID1A are potentially actionable co-alterations. RAS pathway-targeted therapy should be considered.

Phase 1b study of intraperitoneal ipilimumab and nivolumab in patients with recurrent gynecologic malignancies with peritoneal carcinomatosis

BACKGROUND

Intravenous immune checkpoint blockade (ICB) has shown poor response rates in recurrent gynecologic malignancies. Intraperitoneal (i.p.) ICB may result in enhanced T cell activation and anti-tumor immunity.

METHODS

In this phase 1b study, registered at Clinical.

TRIALS

gov (NCT03508570), initial cohorts received i.p. nivolumab monotherapy, and subsequent cohorts received combination i.p. nivolumab every 2 weeks and i.p. ipilimumab every 6 weeks, guided by a Bayesian design. The primary objective was determination of the recommended phase 2 dose (RP2D) of the combination. Secondary outcomes included toxicity, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS).

FINDINGS

The trial enrolled 23 patients: 18 with ovarian cancer, 2 with uterine cancer, and 3 with cervical cancer. Study evaluable patients (n = 16) received a median of 2 prior lines of therapy (range: 1-8). Partial response was observed in 2 patients (12.5%; 1 ovarian, 1 uterine), and complete response was observed in 1 patient (6.3%) with cervical cancer, for an ORR of 18.8% (95% confidence interval: 4.0%-45.6%). The median duration of response was 14.8 months (range: 4.1-20.8), with one complete response ongoing. Median PFS and OS were 2.7 months and not reached, respectively. Grade 3 or higher immune-related adverse events occurred in 2 (8.7%) patients.

CONCLUSIONS

i.p. administration of dual ICB is safe and demonstrated durable responses in a subset of patients with advanced gynecologic malignancy. The RP2D is 3 mg/kg i.p. nivolumab every 2 weeks plus 1 mg/kg ipilimumab every 6 weeks.

FUNDING

This work was funded by Bristol Myers Squibb (CA209-9C7), an MD Anderson Cancer Center Support Grant (CA016672), the Ovarian Cancer Moon Shots Program, the Emerson Collective Fund, and a T32 training grant (CA101642).

Randomized phase 2 trial of tremelimumab and durvalumab in combination versus sequentially in recurrent platinum-resistant ovarian cancer

BACKGROUND

Single-agent immune checkpoint inhibitors (ICIs) have demonstrated limited responses in recurrent ovarian cancer; however, 30%-40% of patients achieve stable disease. The primary objective was to estimate progression-free survival (PFS) after sequential versus combination cytotoxic T-lymphocyte antigen 4 and programmed death ligand 1 ICIs in patients with platinum-resistant high-grade serous ovarian cancer (HGSOC).

METHODS

Patients were randomized to a sequential arm (tremelimumab followed by durvalumab on progression) or a combination arm (tremelimumab plus durvalumab, followed by durvalumab) via a Bayesian adaptive design that made it more likely for patients to be randomized to the more effective arm. The primary end point was immune-related PFS (irPFS).

RESULTS

Sixty-one subjects were randomized to sequential (n = 38) or combination therapy (n = 23). Thirteen patients (34.2%) in the sequential arm received durvalumab. There was no difference in PFS in the sequential arm (1.84 months; 95% CI, 1.77-2.17 months) compared with the combination arm (1.87 months; 95% CI, 1.77-2.43 months) (p = .402). In the sequential arm, no responses were observed, although 12 patients (31.6%) demonstrated stable disease. In the combination arm, two patients (8.7%) had partial response, whereas one patient (4.4%) had stable disease. Adverse events were consistent with those previously reported for ICIs. Patient-reported outcomes were similar in both arms.

CONCLUSIONS

There was no difference in irPFS for combination tremelimumab plus durvalumab compared to tremelimumab alone (administered as part of a sequential treatment strategy) in a heavily pretreated population of patients with platinum-resistant HGSOC. Response rates were comparable to prior reports, although the combination regimen did not add significant benefit, as has been previously described.

Efficacy and safety of autologous tumor-infiltrating lymphocytes in recurrent or refractory ovarian cancer, colorectal cancer, and pancreatic ductal adenocarcinoma

BACKGROUND

Tumor-infiltrating lymphocyte (TIL) therapy has shown efficacy in metastatic melanoma, non-small cell lung cancer, and other solid tumors. Our preclinical work demonstrated more robust CD8 predominant TIL production when agonistic anti-4-1BB and CD3 antibodies were used in early ex vivo TIL culture.

METHODS

Patients with treatment-refractory metastatic colorectal (CRC), pancreatic (PDAC) and ovarian (OVCA) cancers were eligible. Lymphodepleting chemotherapy was followed by infusion of ex vivo expanded TIL, manufactured at MD Anderson Cancer Center with IL-2 and agonistic stimulation of CD3 and 4-1BB (urelumab). Patients received up to six doses of high-dose IL-2 after TIL infusion. Primary endpoint was evaluation of objective response rate at 12 weeks using Response Evaluation Criteria in Solid Tumors version 1.1 with secondary endpoints including disease control rate (DCR), duration of response, progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

17 patients underwent TIL harvest and 16 were treated on protocol (NCT03610490), including 8 CRC, 5 PDAC, and 3 OVCA patients. Median age was 57.5 (range 33-70) and 50% were females. Median number of lines of prior therapy was 2 (range 1-8). No responses were observed at 12 weeks. Ten subjects achieved at least one stable disease (SD) assessment for a DCR of 62.5% (95% CI 35.4% to 84.8%). Best response included prolonged SD in a patient with PDAC lasting 17 months. Median PFS and OS across cohorts were 2.53 months (95% CI 1.54 to 4.11) and 18.86 months (95% CI 4.86 to NR), respectively. Grade 3 or higher toxicities attributable to therapy were seen in 14 subjects (87.5%; 95% CI 61.7% to 98.4%). Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type and low expression of checkpoint markers.

CONCLUSIONS

TIL manufactured with assistance of 4-1BB and CD3 agonism is feasible and treatment is associated with no new safety signals. While no responses were observed, a significant portion of patients achieved SD suggesting early/partial immunological effect. Further research is required to identify factors associated with resistance and functionally enhance T cells for a more effective therapy.

Phase 1/2 trial of avelumab combined with utomilumab (4-1BB agonist), PF-04518600 (OX40 agonist), or radiotherapy in patients with advanced gynecologic malignancies

BACKGROUND

Immune checkpoint blockade has shown mixed results in advanced/recurrent gynecologic malignancies. Efficacy may be improved through costimulation with OX40 and 4-1BB agonists. The authors sought to evaluate the safety and efficacy of avelumab combined with utomilumab (a 4-1BB agonist), PF-04518600 (an OX40 agonist), and radiotherapy in patients with recurrent gynecologic malignancies.

METHODS

The primary end point in this six-arm, phase 1/2 trial was safety of the combination regimens. Secondary end points included the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors and immune-related Response Evaluation Criteria in Solid Tumors, the disease control rate (DCR), the duration of response, progression-free survival, and overall survival.

RESULTS

Forty patients were included (35% with cervical cancer, 30% with endometrial cancer, and 35% with ovarian cancer). Most patients (n = 33; 83%) were enrolled in arms A-C (no radiation). Among 35 patients who were evaluable for efficacy, the ORR was 2.9%, and the DCR was 37.1%, with a median duration of stable disease of 5.4 months (interquartile range, 4.1-7.3 months). Patients with cervical cancer in arm A (avelumab and utomilumab; n = 9 evaluable patients) achieved an ORR of 11% and a DCR of 78%. The median progression-free survival was 2.1 months (95% CI, 1.8-3.5 months), and overall survival was 9.4 months (95% CI, 5.6-11.9 months). No dose-limiting toxicities or grade 3-5 immune-related adverse events were observed.

CONCLUSIONS

The findings from this trial highlight that, in heavily pretreated patients with gynecologic cancer, even multidrug regimens targeting multiple immunologic pathways, although safe, did not produce significant responses. A DCR of 78% in patients with cervical cancer who received avelumab and utomilumab indicates that further research on this combination in select patients may be warranted.

EGFR, HLA-G, CD70, c-MET, and NY-ESO1 as potential biomarkers in high grade epithelial ovarian carcinoma

High grade epithelial ovarian carcinoma is an aggressive tumor. Treatment includes platinum therapy, however it recurs in most patients due to therapy resistance. In this project, we study the immunohistochemical (IHC) expression of five potential biomarkers/prognostic markers in high grade epithelial ovarian carcinoma: EGFR, HLA-G, CD70, c-MET, and NY-ESO1. A cohort of 274 patients is used. We compare the IHC expression with age, stage, ascites status, family history of cancer, disease free survival (DFS) and overall survival (OS). EGFR expression is significantly correlated with family history and worse OS. HLA-G is associated with worse OS. To confirm the results of EGFR and HLA-G, a second separated cohort of 248 patients is used. Positive EGFR expression again shows worse OS, while HLA-G expression has worse prognostic trend. CD70 has a worse OS trend. C-MET and NY-ESO1 do not have any clinical correlations. EGFR can potentially serve as target in future clinical immune therapy trials.

Posterior-scleritis: Case report of an uncommon immune-related adverse event in the treatment of advanced endometrial cancer

As Immune checkpoint inhibitors are being expanded for use in gynecologic malignancies, rare immune-related adverse events are more frequently being reported. Here we describe a 63-year-old with Stage IIIB mismatch repair deficient uterine adenocarcinoma who underwent six cycles of carboplatin and paclitaxel with partial response but persistent disease. She was then started on single agent pembrolizumab. After six cycles of pembrolizumab, she developed bilateral vision changes and was diagnosed with posterior scleritis. Pembrolizumab was held and she was treated with oral prednisone, with rapid resolution of symptoms. One month after completion of prednisone, vision changes were again reported and she was restarted on a longer oral prednisone course. She then underwent definitive surgical management consisting of a total laparoscopic hysterectomy and bilateral salpingo-oophorectomy, with final pathology of benign endometrial hyperplasia. She has completed her steroid course without any symptoms. Given her complete pathologic response, she was subsequently placed into surveillance and is currently without evidence of disease. Prompt recognition and treatment of this rare immune-related adverse event led to the prevention of potential permanent, debilitating outcomes.

Transforming ovarian cancer care by targeting minimal residual disease

Frontline treatment and resultant cure rates in patients with advanced ovarian cancer have changed little over the past several decades. Here, we outline a multidisciplinary approach aimed at gaining novel therapeutic insights by focusing on the poorly understood minimal residual disease phase of ovarian cancer that leads to eventual incurable recurrences.

Pan-cancer T cell atlas links a cellular stress response state to immunotherapy resistance

Tumor-infiltrating T cells offer a promising avenue for cancer treatment, yet their states remain to be fully characterized. Here we present a single-cell atlas of T cells from 308,048 transcriptomes across 16 cancer types, uncovering previously undescribed T cell states and heterogeneous subpopulations of follicular helper, regulatory and proliferative T cells. We identified a unique stress response state, TSTR, characterized by heat shock gene expression. TSTR cells are detectable in situ in the tumor microenvironment across various cancer types, mostly within lymphocyte aggregates or potential tertiary lymphoid structures in tumor beds or surrounding tumor edges. T cell states/compositions correlated with genomic, pathological and clinical features in 375 patients from 23 cohorts, including 171 patients who received immune checkpoint blockade therapy. We also found significantly upregulated heat shock gene expression in intratumoral CD4/CD8+ cells following immune checkpoint blockade treatment, particularly in nonresponsive tumors, suggesting a potential role of TSTR cells in immunotherapy resistance. Our well-annotated T cell reference maps, web portal and automatic alignment/annotation tool could provide valuable resources for T cell therapy optimization and biomarker discovery.

Clinical implications of tumor-based next-generation sequencing in high-grade epithelial ovarian cancer

BACKGROUND

Tumor-based next-generation sequencing is used inconsistently as a tool to tailor treatment of ovarian cancer, yet beyond detection of somatic BRCA1 and BRCA2 mutations, the clinical benefit is not well established. This study aimed to assess the clinical relevance of tumor-based next-generation sequencing (tbNGS) in patients with ovarian cancer.

METHODS

This retrospective study included patients with high-grade epithelial ovarian carcinoma. tbNGS results were identified in the electronic medical record using optical character recognition and natural language processing. Genetic, clinical, and demographic information was collected. Progression-free survival (PFS) and overall survival were calculated and compared using log-rank tests. Multivariate Cox regression and clustering analyses were used to identify patterns of genetic alterations associated with survival.

RESULTS

Of 1092 patients in the described population, 409 (37.5%) had tbNGS results. Nearly all (96.1% [393/409]) had one or more genetic alterations. In 25.9% (106/409) of patients, an alteration that aligned with a targeted treatment was identified, and in an additional 48.7% (199/409), tbNGS results suggested eligibility for an investigational agent or clinical trial. The most frequent alterations were TP53, PIK3CA, and NF1 mutations, and CCNE1 amplification. Together, BRCA1 and BRCA2 mutations were associated with longer PFS (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.42-0.92; p = .02), whereas AKT2 amplification was associated with shorter PFS (HR, 3.86; 95% CI, 1.002-14.88; p < .05). Multivariate Cox regression and clustering analyses identified several combinations of genetic alterations that corresponded to outcomes in patients with high-grade serous carcinoma.

CONCLUSIONS

tbNGS often yields clinically relevant information. Detailed analysis of population-level tumor genomics may help to identify therapeutic targets and guide development of clinical decision support tools.

PLAIN LANGUAGE SUMMARY

Although more and more patients with ovarian cancer are undergoing tumor-based next-generation sequencing to identify genetic mutations in their tumors, the benefits of such testing are not well established. In a group of over 400 patients with ovarian cancer who underwent tumor-based next-generation sequencing in the course of their treatment, nearly all patients had one or more genetic alterations detected, and one out of four patients had a mutation that qualified them for a personalized treatment option.

Predictors of Oncologic Outcome in Patients Receiving Phase I Investigational Therapy for Recurrent or Metastatic Cervical Cancer

Introduction

We aimed to identify clinical, pathologic, and treatment factors that are predictive of response and survival in patients with cervical cancer referred to phase I clinical trials.

Methods

Patients with cervical cancer who received at least one dose of a phase I investigational agent at our institution between 2014 and 2022 were included. The log-rank test was used to analyze differences in progression-free survival (PFS) and overall survival (OS), and multivariable regression analysis was performed.

Results

We included 65 patients with a median age of 41 years (range, 20-74), 3 prior therapies (range, 1-7), and 67.7% squamous carcinoma. The rate of distant metastasis at trial entry was 84.6%. The most common molecular alterations included PIK3CA (46.5%), PD-L1+ (46.2%), EPH (30.0%), and CREBBP (23.1%); 23.1% had received a prior checkpoint inhibitor. Phase I trials were for immunotherapy (58.5%) or targeted therapy (41.5%). The rate of biomarker matching was 21.5%. For all patients, median PFS was 3.6 months (95% CI, 2.0-5.2) and OS was 9.3 months (95% CI, 7.0-10.6). Factors at study entry associated with worse survival were presence of bone metastasis (PFS 1.6 vs 4.4 months: hazard ratio [HR], 2.8; p = 0.001; OS 3.8 vs 10.0 months: HR, 3.9; p < 0.0001) and absolute lymphocyte count below 1000/μL (PFS 1.8 vs 5.2 months: HR, 2.9; p = 0.0004; OS 7.0 vs 10.6 months: HR, 3.2; p = 0.0009). Factors associated only with worse OS were absolute neutrophil count above 4700/μL, hemoglobin below 10.5 g/dL, and smoking status. Grade 3+ treatment-related adverse events were seen in 16.9% of cases.

Conclusion

Bone metastasis and absolute lymphocyte count below normal range at phase I study entry portend poor survival in patients with recurrent or metastatic cervical cancer.

Gynecologic tract melanoma in the contemporary therapeutic era: High rates of local and distant disease progression

BACKGROUND

Gynecologic tract melanoma (GTM) is a rare malignancy with historically poor outcomes. The current study examines patterns of care and oncologic outcomes in a large single-institution cohort from the contemporary therapeutic era.

METHODS

Patterns of care and predictors of outcomes were evaluated for all GTM patients without metastatic disease at diagnosis who were treated at our institution between 2009 and 2020 with >6 months of follow-up.

RESULTS

Of the 124 patients included, anatomic subsites were vulvar (n = 82, 66%), vaginal (n = 34, 27%), or cervical (n = 8, 6%). Primary tumor was resected for 85% (n = 106) with surgical nodal evaluation for 60% (n = 75). Systemic therapy, most commonly immune checkpoint inhibitors (ICI, 58% systemic therapy), was used to treat all except one unresectable patient (17/18) and 33% (35/106) of resectable patients. Seven patients received neoadjuvant ICI. Fourteen patients received adjuvant radiation therapy to the pelvis (RT, 13% of those undergoing resection). With a median follow-up of 45 months, 100 patients (81%) recurred. Four-year actuarial outcomes were: 46% local control, 53% nodal control, 36% distant metastasis-free survival, 17% disease-free survival, 49% melanoma-specific survival and 48% overall survival. Mitotic rate > 10/mm², nodal involvement and non-vulvar anatomic subsite were associated with poor outcomes. Patients treated after 2016 did not have significantly better outcomes than those treated earlier.

CONCLUSIONS

Patients with GTM continue to have poor outcomes in the contemporary therapeutic era with particularly notable poor local disease control relative to other mucosal melanoma subtypes. More effective oncologic therapy is needed.

Clinical Outcomes of Patients with Recurrent Microsatellite-Stable Endometrial Cancer in Early-Phase Immunotherapy Clinical Trials

Simple Summary

There is a crucial need to improve treatment regimens in patients with recurrent endometrial cancer. Although immunotherapy treatments have shown impressive benefit in microsatellite instability-high endometrial cancer, they have been less predictable in the majority of endometrial cancers, which are microsatellite stable. Our aim was to characterize clinical outcomes in patients with recurrent microsatellite stable endometrial cancer treated in early-phase immunotherapy clinical trials in order unravel treatment regimens that would improve response and survival. Our findings suggest that utilizing immunotherapy in combination with other non-immunotherapy agents resulted in greater duration of disease control and improved survival outcomes compared to immunotherapy only (monotherapy) or in combination with other immunotherapy agents. Future studies are needed to validate these findings.

Abstract

Recurrent microsatellite stable (MSS) endometrial cancer has poor response to conventional therapy and limited efficacy with immune checkpoint monotherapy. We conducted a retrospective study of recurrent MSS endometrial cancer patients enrolled in immunotherapy-based clinical trials at MD Anderson Cancer Center between 1 January 2010 and 31 December 2019. Patients were evaluated for radiologic response using RECIST 1.1 criteria, progression-free survival (PFS), and overall survival (OS). Thirty-five patients were treated with immune checkpoint inhibitors: 8 with monotherapy, 17 with immunotherapy (IO) in combination with another IO-only, and 10 with IO in combination with non-IO therapy. Among those treated with combination IO plus non-IO therapy, one had a partial response but 50% had clinical benefit. Patients who received combination IO plus non-IO therapy had improved PFS compared to those who received monotherapy (HR 0.56, 95% CI 0.33–0.97; p = 0.037) or combination IO-only therapy (HR 0.36, 95% CI 0.15–0.90; p = 0.028) and had improved OS when compared to monotherapy after adjusting for prior lines of therapy (HR 0.50, 95% CI 0.27–0.95; p = 0.036). The potential beneficial clinical outcomes of combination IO plus non-IO therapy in MSS endometrial cancer should be validated in a larger study.

Molecular Profiles of Serum-Derived Extracellular Vesicles in High-Grade Serous Ovarian Cancer

Patients with high-grade serous ovarian cancer (HGSC) who have no visible residual disease (R0) after primary surgery have the best clinical outcomes, followed by patients who undergo neoadjuvant chemotherapy (NACT) and have a response enabling interval cytoreductive surgery. Clinically useful biomarkers for predicting these outcomes are still lacking. Extracellular vesicles (EVs) have been recognized as liquid biopsy-based biomarkers for early cancer detection and disease surveillance in other disease settings. In this study, we performed extensive molecular characterization of serum-derived EVs and correlated the findings with therapeutic outcomes in patients with HGSC. Using EV-DNA whole-genome sequencing and EV-RNA sequencing, we identified distinct somatic EV-DNA alterations in cancer-hallmark genes and in ovarian cancer genes, as well as significantly altered oncogenic pathways between the R0 group and NACT groups. We also found significantly altered EV-RNA transcriptomic variations and enriched pathways between the groups. Taken together, our data suggest that the molecular characteristics of EVs could enable prediction of patients with HGSC who could undergo R0 surgery or respond to chemotherapy.

CRISPR-mediated TGFBR2 knockout renders human ovarian cancer tumor-infiltrating lymphocytes resistant to TGF-β signaling

Background

The correlation between elevated T-cell infiltration and improved survival of ovarian cancer (OvCa) patients suggests that endogenous tumor-infiltrating lymphocytes (TIL) possess some degree of antitumor activity that can be harnessed for OvCa immunotherapy. We previously optimized a protocol for ex vivo OvCa TIL expansion for adoptive cell therapy, which is now being tested in a clinical trial at our institution (NCT03610490). Building on this success, we embarked on genetic modification of OvCa TIL to overcome key immunosuppressive factors present in the tumor microenvironment. Here, we present the preclinical optimization of CRISPR/Cas9-mediated knockout of the TGF-β receptor 2 (TGFBR2) in patient-derived OvCa TIL.

Methods

OvCa TILs were generated from four patients’ tumor samples obtained at surgical resection and subjected to CRISPR/Cas9-mediated knockout of TGFBR2 before undergoing a rapid expansion protocol. TGFBR2-directed gRNAs were comprehensively evaluated for their TGFBR2 knockout efficiency and off-target activity. Furthermore, the impact of TGFBR2 knockout on TIL expansion, function, and downstream signaling was assayed.

Results

TGFBR2 knockout efficiencies ranging from 59±6% to 100%±0% were achieved using 5 gRNAs tested in four independent OvCa TIL samples. TGFBR2 knockout TIL were resistant to immunosuppressive TGF-β signaling as evidenced by a lack of SMAD phosphorylation, a lack of global transcriptional changes in response to TGF-β stimulation, equally strong secretion of proinflammatory cytokines in the presence and absence of TGF-β, and improved cytotoxicity in the presence of TGF-β. CRISPR-modification itself did not alter the ex vivo expansion efficiency, immunophenotype, nor the TCR clonal diversity of OvCa TIL. Importantly for clinical translation, comprehensive analysis of CRISPR off-target effects revealed no evidence of off-target activity for our top two TGFBR2-targeting gRNAs.

Conclusions

CRISPR/Cas9-mediated gene knockout is feasible and efficient in patient-derived OvCa TIL using clinically-scalable methods. We achieved efficient and specific TGFBR2 knockout, yielding an expanded OvCa TIL product that was resistant to the immunosuppressive effects of TGF-β. This study lays the groundwork for clinical translation of CRISPR-modified TIL, providing opportunities for engineering more potent TIL therapies not only for OvCa treatment, but for the treatment of other solid cancers as well.

Abstract 5106: Distinct molecular profiles of serum-derived extracellular vesicles in high-grade serous ovarian cancer

Background: Patients with high-grade serous ovarian cancer (HGSC) who have no visible residual disease (CGR) after primary surgery have the best clinical outcomes, followed by patients who undergo neoadjuvant chemotherapy (NACT) and have response enabling interval cytoreductive surgery. Through comprehensive omics analyses, we previously characterized molecular and cellular profiles of highly clinically defined HGSC from patients who had CGR versus those triaged to NACT. However, clinically useful predictive biomarkers for such distinctions are still lacking. Extracellular vesicles (EVs) have been recognized as liquid biopsy-based biomarkers for early cancer detection and disease surveillance in other disease settings. Here, we performed extensive molecular characterization of serum-derived EVs and correlated them with therapeutic outcomes in patients with HGSC.

Methods: Serum-derived medium/large size EVs from patients with HGSC treated under a systematic surgical algorithm were isolated following standard methods of the International Society for Extracellular Vesicles. Patients had either complete gross resection after primary surgery (R0, n=3); poor response to NACT (NACT-PR, n=4), or excellent response to NACT with carboplatin and paclitaxel (NACT-ER, n=3); tissue and matched germline blood samples have already been comprehensively analyzed (Lee et al, Cell Reports, 2020). The isolated EV-DNA and EV-RNA were subjected to whole-genome sequencing and RNA sequencing, respectively.

Results: We identified somatic EV-DNA alterations in cancer hallmark genes, including FAT1 and KMT2D as the most frequent mutated genes. Interestingly, we found alterations in ovarian cancer-related genes, including BRCA2 and RAD51 in R0; BRCA2 in NACT-ER; TP53, CDK13, CDK12, BRAF, AKT2, and ARID1A in NACT-PR patients. We also identified 26,338 genes expressed in the EV-RNA transcriptomic profiles. The analysis of the enrichment of cancer hallmark pathways showed that the R0 group was more enriched in the interferon α/γ, PI3K/AKT/mTOR signaling, and DNA repair pathways. Interestingly, we also identified 6,757 differentially expressed genes (DEGs) in the CGR versus the NACT groups (absolute log2-fold change ≥2 and adjusted p-value &lt;0.05). Among the DEGs, we identified 67 genes that were cancer hallmark genes, and 21 of them were overexpressed in the NACT group and 46 were overexpressed in the R0 group. Noticeably, 11 DEGs were directly related to ovarian cancer: TP53, PTEN, CCND1, BARD1, PMS2, and MLH3 were significantly overexpressed in the NACT group, while BRCA2, CSMD3, and GABRA6 were overexpressed in the R0 group.

Conclusions: Taken together, our preliminary data suggest that molecular characteristics of EVs could provide an accurate prediction of patients with HGSC who can undergo CGR with surgery and respond to chemotherapy.

Citation Format: Li Zhao, Shaolin Ma, Nicole D. Fleming, Joseph Celestino, Mark S. Kim, Richard A. Hajek, Nicholas B. Jennings, Erika J. Thompson, Hongli Tang, Shannon N. Westin, Amir A. Jazaeri, Jianhua Zhang, P Andrew Futreal, Anil K. Sood, Sanghoon Lee. Distinct molecular profiles of serum-derived extracellular vesicles in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5106.

Abstract 1248: Predictors of innate resistance to pembrolizumab in patients with microsatellite instability-high endometrial cancer

Introduction: Despite FDA approval of pembrolizumab in microsatellite instability-high (MSI-H)/mismatch repair deficient solid tumors, approximately half of patients with MSI-H endometrial cancer are treatment-refractory. We sought to evaluate pre-treatment MSI-H endometrial tumor samples to examine cell subpopulation differences in the tumor microenvironment (TME) associated with resistance to pembrolizumab.

Methods: Archival tumor samples from MSI-H endometrial cancer patients treated with pembrolizumab at MD Anderson Cancer Center were obtained under an IRB-approved protocol. Twenty-one patients were identified, and pre-treatment archival tumor samples were collected and submitted for RNA-seq and imaging mass cytometry (IMC) with an optimized 38-antibody panel to identify predictive immuno-genomic signatures and cell subpopulations associated with treatment response.

Results: Among the 21 patients treated with pembrolizumab, there were 14 responders and 7 non-responders. Based on transcriptomic signatures, TME heterogeneity was observed. The 14 responders consisted of samples with immunologically “hot” (5/5; 100%), “cold” (6/8; 75%), and “warm” TMEs (3/8; 37.5%) while the 7 non-responders consisted of only “cold” (2/8; 25%) and “warm” (5/8; 62.5%) TME samples. There was an enrichment of fibroblasts and endothelial cell transcriptomic signatures in the samples of the non-responders compared to responders (p=0.018) with a trend of increasing enrichment in those signatures as response strength decreased. IMC performed on archival tissue from 20 patients demonstrated similar trend of higher population of activated fibroblasts (SMA+, MFAP5+) and endothelial cells (CD31+) in non-responders. Furthermore, non-responders had significantly higher total regulatory T cells (CD4+FOXP3+) in the tumor (p=0.027) and stroma (p=0.0282) compared to responders. Additionally, significantly higher activated regulatory T cells (CD4+FOXP3+CD25+) were observed in the tumor (p=0.016) and stroma (p=0.008) of non-responders compared to responders. Similar abundance of total and subpopulations of CD8+ T cells were observed between responders and non-responders.

Conclusion: The MSI-H endometrial TME is heterogeneous. Increased presence of fibroblasts, endothelial cells, and regulatory T-cells in the TME correlate with innate resistance to pembrolizumab. Treatment aimed toward the reduction of these cellular subpopulations may improve sensitivity to PD-1 inhibitors. Future studies are needed to validate these findings.

Citation Format: Jeffrey A. How, Minghao Dang, Sammy Ferri-Borgogno, Elizabeth Euscher, Melinda S. Yates, Weiyi Peng, Shrina D. Patel, Jared J. Burks, Ivo Vletic, Javier Gomez, Karen Lu, Samuel C. Mok, Linghua Wang, Amir A. Jazaeri. Predictors of innate resistance to pembrolizumab in patients with microsatellite instability-high endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1248.

Abstract 5738: Transcriptomic profiles of response to neoadjuvant chemotherapy in patients with high-grade serous ovarian cancer

Background: High-grade serous ovarian cancer (HGSC) is the most aggressive epithelial ovarian cancer, exhibiting tumor heterogeneity, molecular abnormality, and variable clinical outcomes. The heterogeneity and apparent adaptability of the HGSC genome under selective pressure by chemotherapy likely explain the high rates of drug resistance in HGSC. However, the underlying mechanisms of drug resistance are not well understood. Following our previous findings of significant distinct molecular and cellular characteristics in pre-treatment tumor samples from highly clinically annotated HGSC patients who received neoadjuvant chemotherapy (NACT), we examined post-treatment transcriptomic changes associated with excellent or poor responders to NACT in HGSC patients.

Methods: Thirty tumor tissues (pre- and post-treatment) after 3 to 4 cycles of NACT were collected from HGSC patients at interval cytoreductive debulking surgery from the following groups: excellent response to NACT with carboplatin/paclitaxel (post-ER, n=8); poor response to NACT (post-PR, n=8). Primary or metastatic sites for each patient were obtained (n=13, post-ER; n=17, post-PR) and subjected to RNA sequencing. The downstream bioinformatics analysis was then performed and compared with the data from the matched pre-NACT samples from the same patients (Lee et al., Cell Reports, 2020).

Results: We identified a total of 9,764 upregulated and 2,762 downregulated differentially expressed genes (DEGs, absolute log2FC &gt;=2, adj-p&lt;0.05) in the post-NACT samples vs the pre-NACT samples in the ER group. In contrast, 11,246 upregulated and 1,320 downregulated DEGs were found in the NACT-PR group. Ovarian cancer-related genes, including KRAS, NRAS, BRCA1/2, RB1, NF1, MLH1, PIK3CA, MSH2, AKT1, and NOTCH3 were differentially expressed in post-NACT vs pre-NACT in both ER and PR groups. TP53 was exclusively upregulated in post-ER vs pre-ER, and GABRA6 was exclusively upregulated in post-PR vs pre-PR. In signaling pathway analysis, apoptosis and DNA repair-related pathways were exclusively downregulated in post-ER vs pre-ER. Interestingly, the percentage of immune cells − CD8 and macrophages M0 were significantly elevated in post-ER (p&lt;0.05), while γδ T cells and activated dendritic cells were significantly decreased in the post-ER (p&lt;0.05), not in the PR. Neutrophil cells were significantly lower in post-PR vs pre-PR, but not in ER group. We also found that the level of ESR1 decreased significantly in post-ER vs post-PR (p&lt;0.05). The level of PAX8 significantly increased in post-PR vs post-ER (p&lt;0.05).

Conclusions: Our transcriptomic analysis revealed distinct transcripts changes in post-NACT vs pre-NACT tumor tissues from HGSC patients with excellent or poor response to the NACT. These findings could enhance treatment decision-making and rationale for developing alternative therapies for patients with HGSC.

Citation Format: Sanghoon Lee, Li Zhao, Nicole D. Fleming, Joseph Celestino, Richard A. Hajek, Margaret B. Morgan, Yan Liu, Shannon N. Westin, Amir A. Jazaeri, Jinsong Liu, Jianhua Zhang, P Andrew Futreal, Anil K. Sood. Transcriptomic profiles of response to neoadjuvant chemotherapy in patients with high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5738.

Abstract 4135: Initial clinicopathologic and molecular characterization of minimal residual disease detected by second look laparoscopy after completion of frontline surgery and chemotherapy in patients with advanced stage ovarian cancer

Background: Despite high rates of remission after frontline management, most patients with advanced stage ovarian cancer recur. Second look laparoscopy (SLL) can provide more sensitive detection of minimal residual disease (MRD) allowing for more individualized prognostication and possible therapeutic intervention. It may also assess tumor biology and microenvironment associated with undetectable chemoresistant MRD phase of ovarian cancer. The objective of this study was to determine SLL feasibility, and clinicopathologic and molecular characteristics of MRD after frontline therapy in ovarian cancer.

Methods: SLL was offered to patients with stage III-IV high grade epithelial ovarian cancer who achieved complete response after frontline surgery and 6 cycles of carboplatin and paclitaxel chemotherapy. Patients were offered standard of care or investigational management options based on homologous recombination deficiency (HRD) and MRD status at SLL. Preliminary translational studies included RNAseq for comparison of serial, matched tumor from primary or interval TRS and SLL derived MRD+ biopsies at the time of SLL. In addition, Nanostring analyses of SLL surgical biopsies both with and without residual tumor were performed. Molecular profiling employed hierarchical clustering, principle component analysis, non-parametric testing, and pathway analyses.

Results: Between 4/2017- 7/2021, 39 patients underwent SLL. The majority had stage III disease (74%), high grade serous histology (90%) and underwent neoadjuvant chemotherapy with interval tumor reductive surgery (TRS; 54%). MRD was present in 49% (n=19) of patients and was more frequent among neoadjuvant chemotherapy recipients (73% vs 26%, P=0.015) and patients with homologous recombination proficient tumors (81% vs 25%, P=0.01). Most patients without MRD were dispositioned to observation; 4 patients with HRD received a PARP inhibitor per standard of care. All other patients with MRD received bevacizumab as part of a clinical trial, except for one patient who received a PARP inhibitor. Median follow-up was 6.74 months (range 0.66 - 28.62). Presence of MRD was associated with worse PFS (HR 3.7, 95% CI 1.3- 10.9; 5.5 vs 24.6 months; P= 0.02). Based on transcriptional signature, MRD are immunologically distinct from untreated tumors or those collected at interval TRS (after 3 cycles of chemo) but also displayed heterogeneity with two distinct subclusters.

Conclusions: SLL to assess for MRD has potential to further individualize post-frontline therapy, and identify patients at high risk for progression for early intervention clinical trials. Transcriptional profiling suggests that MRD phase of ovarian cancer is characterized by a distinct, heterogeneous, and evolving tumor and immune microenvironment.

Citation Format: Roni Nitecki, Minghao Dang, Sanghoon Lee, Bryan Fellman, J Alejandro Rauh-hain, Jolyn Taylor, Lois Ramondetta, Michaela Grinsfelder, Lauren Cobb, David M. Boruta, Pamela T. Soliman, Aaron Shafer, Nicole D. Fleming, Shannon N. Westin, Anil K. Sood, Chris Tanguma, Pedro T. Ramrez, Karen H. Lu, Linghua Wang, Amir A. Jazaeri. Initial clinicopathologic and molecular characterization of minimal residual disease detected by second look laparoscopy after completion of frontline surgery and chemotherapy in patients with advanced stage ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4135.

First-in-human phase 1/2 study of autologous T cells engineered using the Sleeping Beauty System transposon/transposase to express T-cell receptors (TCRs) reactive against cancer-specific mutations in patients with advanced solid tumors

TPS2679

Background: In 2022 approximately 1.7 million Americans will die from solid cancers. Recently there have been significant advances in the genetic engineering of T lymphocytes to recognize neoantigens on tumors in vivo, resulting in remarkable cases of tumor regression and remission. Cancer cells frequently harbor KRAS, TP53, and EGFR somatic hotspot mutations that can be processed and presented by tumor HLA as neoantigens to T cells through their T-cell receptor (TCR). These neoantigens are not present in the normal tissues; thus, they are attractive targets for adoptive T cell therapy. Given the number and complexity of different neoantigen/HLA combinations on solid tumors, a TCR library approach is warranted. Therefore, we have developed a library of TCR-T cell therapies including those targeting shared KRAS, TP53 and EGFR mutations. Methods: Patients for whom a TCR matching the subject’s somatic mutation(s) and HLA type is available in our TCR library, and have progressive or recurrent disease following standard therapy are eligible for enrollment on this protocol. Patients with the following tumor types will be enrolled: ovarian, endometrial, colorectal, pancreatic, cholangiocarcinoma, and non-small cell lung cancer. This first-in-human study includes Screening, Pre-Treatment, Treatment and Follow-up Periods. During the Pre-Treatment Period, subjects will undergo apheresis for PBMCs isolation. The PBMCs will be transposed using the Sleeping Beauty system to express the subject’s mutation specific TCR. Bridging therapy after apheresis is allowed once the apheresis product has been accepted. During the Treatment Period, patients will undergo lymphodepletion with cyclophosphamide and fludarabine. After which, the TCR-T cell drug product will be administered to the subject by infusion at the assigned dose level. The starting dose level of Arm A (monotherapy) will be DL1 (5 x10 9 TCR+ Cells) administered on Day 0. Dose escalation will continue utilizing the accelerated BOIN design (planned escalation dose levels: 5 x10 9, 4 x10 10 and 1 x10 11 TCR+ Cells). In Arm B, if initiated by protocol, subjects will also receive aldesleukin (interleukin-2) infusion starting on Day 0 (within 24 hours of TCR-T cell product infusion) at 720K IU/kg, every eight hours for up to 4 days. The Follow-up Period will begin after the subject completes their Day 28 visit. Clinical and radiologic response will be assessed at 6 and 12 weeks after TCR-T cell drug product infusion and every 12 weeks thereafter until up to 2 years or study discontinuation (e.g., disease progression, initiation of new anti-cancer therapy, consent withdrawn), whichever occurs first. All subjects will continue to be followed in the Long-Term Follow-up Protocol for up to 15 years post-TCR-T cell drug product infusion. Clinical trial information: NCT05194735.

GRN300–001: Phase 1/1B evaluation of the safety, pharmacokinetics, and efficacy of GRN-300, a salt-inducible kinase inhibitor, alone and in combination with paclitaxel, in recurrent ovarian, primary peritoneal, and fallopian tube cancers

TPS5616

Background: Salt-induced kinase 2 (SIK2) is a serine-threonine kinase that regulates centrosome splitting, activation of PI3 kinase and phosphorylation of Class IIa HDACs. SIK2 is overexpressed in 30% of ovarian cancers and associated with decreased progression-free survival (Ahmed et al., 2010). Treatment with GRN-300, an orally bioavailable small-molecule inhibitor of SIK2, was shown to improve the response to paclitaxel in human ovarian cancer cells grown in culture and in immunocompromised mice (Zhou et al., 2017). Methods: Part 1 of the study will evaluate the safety, MTD, RP2D (Recommended Phase 2 Dose), and PK of daily GRN-300 monotherapy. For the dose-escalation enrollment of patients with advanced solid tumors of any histology, four dose levels of GRN-300 are planned: 100, 200, 300, and 400 mg BID. Subsequently, GRN-300 will be administered at the determined RP2D in an ovarian cancer expansion cohort. Part 2 will evaluate the safety, PK, and preliminary clinical activity in an open-label study of the combination of GRN-300 and paclitaxel weekly x3. Paclitaxel will be administered in one of two different dosing levels: 60 mg/m2 initially, then dose escalated to 80 mg/m2. In the combination regimen, GRN-300 will be administered at the RP2D dose as determined in Part 1 of this study. The two dose findings will be conducted independently using the BOIN design (Liu 2015, Yuan 2016). Study drug may be administered per protocol for continuous 28-day cycles until disease progression, adverse events, or other criteria as described in the protocol. Tumor biopsies and blood plasma samples including peripheral blood mononuclear cells (PBMCs) will be collected for exploratory biomarker analysis to predict and to monitor responses to GRN-300 treatment. Major eligibility criteria At least 18 years of age. Recurrent or persistent, locally non-resectable or metastatic ovarian, primary peritoneal or fallopian tube epithelial cancer (advanced solid tumors of any other histology only for the monotherapy dose escalation enrollment in Part 1) In Part 2, diagnosis of recurrent or persistent, locally non-resectable or metastatic ovarian, primary peritoneal or fallopian tube epithelial cancer for which treatment with paclitaxel is indicated. Received at least one prior second-line treatment. The first 3 dose groups (100, 200, and 300 mg BID of GRN-300) have been completed without DLT and preliminary PK analysis indicate dose proportionality. Enrollment to dose group 4 (400 mg BID) began in February 2022. Clinical trial information: NCT04711161.

A pilot phase II study of neoadjuvant fulvestrant plus abemaciclib in women with advanced low-grade serous carcinoma

5522

Background: Neoadjuvant chemotherapy has demonstrated limited activity in low-grade serous carcinomas (LGSOC) of the ovary, fallopian tube, and peritoneum, with objective response rate of 11% and complete gross resection (CGR) rate of 38% at the time of interval cytoreductive surgery (ICS). LGSOC has many similarities to hormone receptor positive (HR+) breast cancer, including clinical benefit from endocrine therapies in the recurrent and maintenance settings. Based on the activity of antiestrogen plus CDK4/6 inhibitor combination therapy in HR+ breast cancer, we conducted a phase II pilot study to assess the clinical benefit of neoadjuvant treatment with fulvestrant and abemaciclib for women with advanced LGSOC. Methods: Women with unresectable, untreated stage III or IV LGSOC of the ovary, fallopian tube or peritoneum were eligible. Patients received fulvestrant (500 mg IM on day 1 and 15 of the first 28-day cycle, followed by day 1 of subsequent cycles) and abemaciclib 150 mg orally BID. Pre/perimenopausal patients also received goserelin 10.8 mg subcutaneously every 12 weeks for ovarian suppression. Patients continued treatment until deemed resectable by the treating surgeon with imaging re-assessment every 8 weeks using RECIST 1.1. Following ICS, patients receive 4 cycles of adjuvant fulvestrant and abemaciclib and then transition to maintenance letrozole. Patients with progressive disease (PD) were removed from study and received standard of care chemotherapy. Primary endpoint is clinical benefit rate (CBR). Results: Fifteen patients were enrolled and evaluable. At data cutoff date (January 20, 2022), 7 of 15 patients (47%) had partial response (PR) (one patient with radiologic PR had a pathologic complete response at ICS), 5 of 15 (33%) had stable disease (SD), and 3 of 15 (20%) had progressive disease (PD), resulting in a CBR of 80%. Of the 7 patients with PR, 3 have had ICS with CGR, 3 have not yet had ICS, and 1 underwent resection of supraclavicular disease with small volume residual disease in the chest. Of the 5 patients with SD, one underwent ICS with CGR, and two have been on treatment for 8 and 16 weeks with reduction in measurable disease but not yet deemed to be candidates for surgery. Four of the 5 patients (80%) who had ICS, had CGR. Median time on study prior to surgery was 24 weeks. Adverse events (grade 3 or 4) possibly related to abemaciclib occurred in 2 patients (13.3%) and included acute kidney injury (6.7%) and neutropenia (6.7%). Conclusions: Neoadjuvant treatment with fulvestrant and abemaciclib was tolerable and demonstrated unprecedented response and CGR rates in this pilot study. These results compare favorably to published outcomes of neoadjuvant chemotherapy in LGSOC. Further studies are planned to explore this new treatment option in a larger study population. Clinical trial information: NCT03531645.

Efficacy and safety of autologous expanded tumor infiltrating lymphocytes (TILs) in multiple solid tumors

2536

Background: TIL therapy has been used extensively in metastatic melanoma patients for many years, now with ongoing efforts to commercialize treatment. The efficacy of TIL outside of melanoma is largely unknown thus we designed and implemented a trial using TIL manufactured at a single academic center for treatment refractory metastatic colorectal (CRC), pancreas (PDAC) and ovarian (OVA) cancers. Methods: Patients with CRC, PDAC and OVA refractory to standard therapies with ECOG PS 0-1 and normal organ function were eligible for TIL harvest. Ex vivo TIL expansion and manufacturing was conducted at the MD Anderson TIL lab under conditions that included IL2 and 41BB stimulation (using urelumab). All patients received a lymphodepletion regimen consisting of cyclophosphamide 60mg/kg days -7 and -6 and fludarabine 25mg/m2 days -5 through day -1, followed by infusion of pooled ex-vivo expanded TIL. Patients received up to 6 doses of high dose IL-2 (600,000 IU/kg) after TIL infusion. The primary endpoint was evaluation of the objective response rate (ORR) using RECIST 1.1 criteria with secondary endpoints including disease control rate, duration of response, PFS, OS and safety. Results: A total of 17 patients underwent TIL harvest and 16 were treated on protocol; including 8 CRC, 5 PDAC and 3 OVA. Median age was 57.5 (range 33-70) and 50% were females. Median number of lines of prior therapy was 2 (range 1-8). Median number of TIL infused was 76 X 109 (range 20.3 x 109-150 x 109). Median doses of cyclophosphamide and fludarabine administered were 2 (range, 2-2) and 3 (range, 1-5), respectively. Median doses of IL-2 administered was 6 (range, 1-6). There were no responders. Best response included prolonged SD in a patient with PDAC lasting until 18 months. Grade 3 or higher toxicities attributable to therapy was seen in 14 subjects (87.5%; 95% CI: 61.7 – 98.4) with the majority of toxicities representing expected pancytopenia from lymphodepletion. Infusion product analysis showed the presence of effector memory cells with high expression of CD39 irrespective of tumor type. Early on-treatment biopsy of PDAC patient with prolonged SD showed presence of proliferating (KI67+) CD4+ and CD8+ TIL. Conclusions: Generation of TIL at a single academic center for CRC, PDAC and OVA is feasible and treatment is associated with no new safety signals. For these tumor types, further research is required to identify host factors associated with resistance to TIL therapy and optimize manufacturing processes to create more effective TIL cell therapy. Clinical trial information: NCT03610490.

Clinical implications of tumor-based next-generation sequencing in ovarian cancer

5545

Background: Epithelial ovarian cancer is genetically heterogeneous, both among and within histologic subtypes. Advances in next-generation sequencing have made it feasible to ascertain the somatic genetic signature of each patient, however, critical analysis of population-level sequencing results is required to maximize the potential of this technology. Here, we aimed to assess the clinical relevance of tumor-based next-generation sequencing (tbNGS) in a large cohort of patients with high-grade epithelial ovarian cancer. Methods: Our study population comprised patients with high-grade serous (n = 972), clear cell (n = 33), endometrioid (n = 28), mucinous (n = 4), and mixed (n = 34) or unspecified (n = 21) epithelial ovarian carcinoma diagnosed between April 2013 and September 2021. tbNGS results were identified within the electronic medical record using optical character recognition and natural language processing. Genetic, clinical, and demographic information was collected for patients who had undergone tbNGS. Progression-free survival (PFS) and overall survival (OS) were calculated from date of first treatment to date of first recurrence and date of death, respectively. Data were analyzed using descriptive statistics, univariate and multivariate Cox regression models, and clustering analyses. Results: Of 1092 patients in the described population, 409 (37.5%) had tbNGS results identified. Nearly all (96.1%) revealed one or more genetic aberrations. Most patients (74.6%) had an actionable mutation, defined as relaying eligibility for a targeted treatment or clinical trial. The most frequent alterations were TP53, PIK3CA, and NF1 mutations; and CCNE1 amplification. Ten different targeted institutional and commercial panels were employed, covering a range of 35 to 600+ gene loci. The median time from diagnosis to testing was 14.5 months, likely corresponding to time of recurrence. Though no standalone alterations were significantly related to survival, multivariate and clustering analyses identified several genetic patterns which corresponded to patient outcomes. Mutation of BRAF, PIK3R1, NOTCH3, MET, and/or ATR was correlated with shorter PFS (HR 1.84, p = 0.001); mutation of ATM, RB1, CDKN2A, FGFR1, and/or FGFR2 was associated with improved PFS (HR 0.64, p = 0.04), as was mutation of NBN and/or ATRX (HR 0.54, p < 0.05). MYC, NOTCH3, and/or CREBBP mutations were significantly correlated with worse OS (HR 1.95, p = 0.02). In our population, 40 patients (9.78%) were enrolled in genotypically-relevant clinical trials. Conclusions: tbNGS is prevalent at our institution, and often yields actionable information. We identified several mutational patterns that correlate to patient survival. Detailed analysis of population-level tumor genomics may help to identify therapeutic targets and guide development of clinical decision support tools.

Clinically translatable cytokine delivery platform for eradication of intraperitoneal tumors

Proinflammatory cytokines have been approved by the Food and Drug Administration for the treatment of metastatic melanoma and renal carcinoma. However, effective cytokine therapy requires high-dose infusions that can result in antidrug antibodies and/or systemic side effects that limit long-term benefits. To overcome these limitations, we developed a clinically translatable cytokine delivery platform composed of polymer-encapsulated human ARPE-19 (RPE) cells that produce natural cytokines. Tumor-adjacent administration of these capsules demonstrated predictable dose modulation with spatial and temporal control and enabled peritoneal cancer immunotherapy without systemic toxicities. Interleukin-2 (IL2)-producing cytokine factory treatment eradicated peritoneal tumors in ovarian and colorectal mouse models. Furthermore, computational pharmacokinetic modeling predicts clinical translatability to humans. Notably, this platform elicited T cell responses in NHPs, consistent with reported biomarkers of treatment efficacy without toxicity. Combined, our findings demonstrate the safety and efficacy of IL2 cytokine factories in preclinical animal models and provide rationale for future clinical testing in humans.

Expansion of Candidate HPV-Specific T Cells in the Tumor Microenvironment during Chemoradiotherapy Is Prognostic in HPV16+ Cancers

Human papillomavirus (HPV) infection causes 600,000 new cancers worldwide each year. HPV-related cancers express the oncogenic proteins E6 and E7, which could serve as tumor-specific antigens. It is not known whether immunity to E6 and E7 evolves during chemoradiotherapy or affects survival. Using T cells from 2 HPV16⁺ patients, we conducted functional T-cell assays to identify candidate HPV-specific T cells and common T-cell receptor motifs, which we then analyzed across 86 patients with HPV-related cancers. The HPV-specific clones and E7-related T-cell receptor motifs expanded in the tumor microenvironment over the course of treatment, whereas non-HPV-specific T cells did not. In HPV16⁺ patients, improved recurrence-free survival was associated with HPV-responsive T-cell expansion during chemoradiotherapy.

Safety and efficacy of percutaneous transabdominal and transesophageal decompression gastric catheters for palliation of malignant bowel obstruction

PURPOSE

To evaluate the safety and primary technical success rate of gastric decompression via percutaneous transabdominal gastrostomy (PTAG) or percutaneous transesophageal gastric (PTEG) catheter placement for management of malignant bowel obstruction (MBO). A secondary purpose was to evaluate the safety and success rate for PTAG catheter placement in patients with both MBO and ascites.

METHODS

A single-institution retrospective review of 385 patients who underwent attempted decompression gastric catheter placement from March 2013 to August 2018 was performed. Medical records and imaging studies were reviewed. A subgroup of patients with concomitant MBO and ascites were identified. The primary outcome measures were procedural technical success and procedural complications.

RESULTS

394 decompression gastrostomy catheters were attempted from 2013 to 2018, n = 353 PTAG and n = 41 PTEG. The success rate was 95.5% (n = 337 of 353) for PTAG and 97.6% (n = 40 of 41) for PTEG. There were 63 total complications involving 47 (13.9%) patients following PTAG and 13 total complications involving 9 (22.5%) patients following PTEG, P = 0.16. For the subgroup of patients with MBO and ascites, the success rate was 94.8% (n = 182 of 192 patients), and there were 20 complications involving 17 (12.9%) of 132 patients.

CONCLUSION

Gastric decompression for patients with MBO via PTAG or PTEG catheter placement is associated with high success rates and low complications.

Pulmonary resection for tissue harvest in adoptive tumor-infiltrating lymphocyte therapy: Safety and feasibility

BACKGROUND AND OBJECTIVES

Adoptive T-cell therapies (ACTs) using expansion of tumor-infiltrating lymphocyte (TIL) populations are of great interest for advanced malignancies, with promising response rates in trial settings. However, postoperative outcomes following pulmonary TIL harvest have not been widely documented, and surgeons may be hesitant to operate in the setting of widespread disease.

METHODS

Patients who underwent pulmonary TIL harvest were identified, and postoperative outcomes were studied, including pulmonary, cardiovascular, infectious, and wound complications.

RESULTS

83 patients met inclusion criteria. Pulmonary TIL harvest was undertaken primarily via a thoracoscopy with a median operative blood loss and duration of 30 ml and 65 min, respectively. The median length of stay was 2 days. Postoperative events were rare, occurring in only five (6%) patients, including two discharged with a chest tube, one discharged with oxygen, one episode of urinary retention, and one blood transfusion. No reoperations occurred. The median time from TIL harvest to ACT infusion was 37 days.

CONCLUSIONS

Pulmonary TIL harvest is safe and feasible, without major postoperative events in our cohort. All patients were able to receive intended ACT infusion without delays. Therefore, thoracic surgeons should actively participate in ongoing ACT trials and aggressively seek to enroll patients on these protocols.

Phase II trial of MEDI0457 and durvalumab for patients with recurrent/metastatic HPV-associated cancers

2595

Background: Infection with human papillomavirus (HPV) types 16 or 18 drives oncogenesis for the majority of patients (pts) with cervical, anal, and some penile cancers via viral oncoproteins E6 and E7. While anti-PD1/PD-L1 antibodies have activity in pts with HPV-associated cancers, the majority do not derive benefit from these agents as monotherapy. MEDI0457, a therapeutic DNA vaccine containing plasmids for E6 and E7 oncogenes for HPV-16/18 and IL-12 adjuvant, has been shown to be safe and to provoke an immune response against the expressed antigens. We tested MEDI0457 with the anti-PD-L1 antibody durvalumab for pts with recurrent or metastatic HPV-associated cancers with the goal of improving anti-tumor activity. Methods: Pts with HPV-16/18 cervical cancer or rare (anal, penile, vaginal, or vulvar) HPV- associated cancers that were recurrent and/or metastatic following standard therapies were eligible. No prior immunotherapy was allowed. Pts received 7 mg of MEDI0457 intramuscularly (weeks 1, 3, 7, 12, and every 8 weeks thereafter) and durvalumab 1500 mg intravenously every 4 weeks starting at week 4. The primary endpoint was best overall response according to RECIST 1.1. Adverse events (AE) were assessed using CTCAE v4.03. A Simon two-stage phase 2 trial (Ho: p <.15; Ha: p≥.35) using a one-sided alpha =.05 and beta =.20 was conducted. ≥2 responses were needed in both the “cervical” and non-cervical cohorts during the first stage in order for the trial to proceed. Median progression-free survival (PFS) and overall survival (OS) were estimated via Kaplan-Meier. Results: 41 pts were screened between 11/2018-10/2020. 21 pts (12 cervical, 7 anal, 2 penile) were treated. All 21 were evaluable for toxicity and 19 for response. Median age was 49 years (range, 29-75), and 18 (86%) were female. There were 17 squamous cell carcinomas (SCC) and 4 cervical adenocarcinomas. Grade ≥3 AEs occurred in 3 (14%) pts and included transaminitis, elevated lipase/amylase, hyponatremia, and neutropenia. No AE required study discontinuation. Overall response rate (ORR) was 21% (95% CI, 6-46%) and disease control rate (DCR) was 42% (95% CI, 20-67%). There was one patient with a complete response, 3 with partial response, and 4 with stable disease. All responses were noted among SCCs (1 cervical, 2 anal, 1 penile). Median duration of response among responders is 16 months (range, 11-27). Median PFS was 3.7 months (95% CI, 2.8-9.2), and median OS was 13.5 months (95% CI, 10.1-NA). 6-month PFS rate was 36% (95% CI, 20-65). Conclusions: The combination of MEDI0457 and durvalumab demonstrated acceptable safety/tolerability in pts with advanced HPV-16/18 cancers. Despite a clinically meaningful DCR, the low ORR among pts with cervical cancer led to study discontinuation for futility. Correlative studies are ongoing to characterize pts with prolonged disease control with study treatment. Clinical trial information: NCT03439085.

Selinexor in combination with weekly paclitaxel in patients with advanced or metastatic solid tumors: Results of an open label, single-center, multiarm phase 1b study

5565

Background: Selinexor is a first-in-class novel, oral potent selective inhibitor of nuclear export (SINE) which blocks Exportin-1 (XPO1) leading to nuclear accumulation and activation of tumor suppressor proteins and prevention of translation of proto-oncogenes. Weekly paclitaxel is a standard chemotherapy regimen used in various tumor types. Preclinical models show that selinexor with paclitaxel exerts antitumor activity against multiple solid tumors. Our objective was to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of selinexor and weekly paclitaxel. Methods: This was an open label, single-center, multi-arm phase 1b study utilizing a “3 + 3” design and a “basket type” expansion. Selinexor (twice weekly orally) and weekly paclitaxel (80mg IV 2 week on, 1 week off) was employed as one of 13 parallel arms. Two dose levels (DL) of selinexor were explored: DL1 selinexor 60mg; DL2 selinexor 80mg. Patients (pts) with advanced or metastatic solid tumors were eligible if they had adequate bone marrow and organ function. There was no limit on prior lines of therapy. Efficacy was evaluated using RECIST 1.1. Progression free survival (PFS) was defined as time from treatment until disease progression or death. Results: Of 35 pts treated, all were evaluable for toxicity, and 31 (88%) were evaluable for response. Pt diagnoses included ovarian (n = 28), breast (n = 4), prostate (n = 2), and cervical (n = 1) cancer. Pts had a median of four prior therapies (range 1-10), and 47% had a prior taxane. All pts with ovarian cancer had platinum resistant/refractory disease; high grade serous histology was most common. There were no DLTs and DL1 was chosen as the RP2D given its long term tolerability. 97% of pts had at least one treatment-emergent adverse event (TEAE) and the most common TEAEs were anemia (74%), nausea (57%), fatigue (51%), leukopenia (51%), neutropenia (49%), thrombocytopenia (46%), and vomiting (31%). The most prevalent grade ≥ 3 TEAE were neutropenia (46%), anemia (31%), leukopenia (17%), and fatigue (9 %). Partial responses (PR) were noted in 4 pts (13%); 10 pts (32%) achieved stable disease for > 4 months for a clinical benefit rate (CBR) of 45%. 16 pts (47%) had prior exposure to a taxane, including 1 pt who achieved PR. Among 24 evaluable pts with ovarian cancer, response rate was 17%, CBR was 58%, and PFS was 6.83 months (95% CI 3.73, not reached (NR)). Median duration of clinical benefit in ovarian cancer was 7.57 months (95% CI: 4.43, NR). Conclusions: Oral selinexor in combination with weekly paclitaxel demonstrated promising clinical activity with manageable toxicity, and further evaluation with once weekly selinexor is warranted. This combination should be considered for further exploration in a randomized study, especially in ovarian malignancies. Clinical trial information: NCT02419495.

Toxicity and efficacy of the combination of pembrolizumab with recommended or reduced starting doses of lenvatinib for treatment of recurrent endometrial cancer

OBJECTIVE

We reviewed our institutional data to evaluate toxicity and efficacy outcomes of pembrolizumab/lenvatinib in recurrent endometrial cancer in a "real-world" clinical setting and to compare the impact of reduced lenvatinib starting dose on outcomes.

METHODS

Retrospectively, we reviewed toxicity, treatment responses, and survival outcomes of patients with recurrent endometrial cancer who received ≥1 cycle of pembrolizumab/lenvatinib. We compared subgroups based on lenvatinib starting dose (recommended [20 mg] vs reduced [<20 mg]) and histologic type.

RESULTS

We analyzed 70 patients (recommended dose cohort, n = 16; reduced dose cohort, n = 54). The most common starting dose was 14 mg daily. Compared to the reduced dose cohort, the recommended dose cohort had a significantly higher mean number of lenvatinib dose reductions due to side effects (1.1 vs. 0.4; p = 0.003) and significantly shorter median time to treatment toxicity (1.3 vs. 3.7 days; p = 0.0001). Response rates did not differ significantly between the recommended and reduced dose cohorts (28.6% vs. 38.3%, respectively; p = 0.752). Two patients, both in the reduced dose cohort, had complete responses. Patients with carcinosarcoma histology had response and clinical benefit rates of 25% (3 of 12) and 58.3% (7 of 12), respectively. There were no differences between the 2 dose cohorts with respect to progression-free (p = 0.245) or overall survival (p = 0.858).

CONCLUSION

In clinical practice, a lower starting dose of lenvatinib (14 mg daily) in combination with pembrolizumab was safe and efficacious in recurrent endometrial cancer. The combination produced responses in endometrial carcinosarcomas. Larger studies are required to validate these findings.

SIO: A Spatioimageomics Pipeline to Identify Prognostic Biomarkers Associated with the Ovarian Tumor Microenvironment

Stromal and immune cells in the tumor microenvironment (TME) have been shown to directly affect high-grade serous ovarian cancer (HGSC) malignant phenotypes, however, how these cells interact to influence HGSC patients' survival remains largely unknown. To investigate the cell-cell communication in such a complex TME, we developed a SpatioImageOmics (SIO) pipeline that combines imaging mass cytometry (IMC), location-specific transcriptomics, and deep learning to identify the distribution of various stromal, tumor and immune cells as well as their spatial relationship in TME. The SIO pipeline automatically and accurately segments cells and extracts salient cellular features to identify biomarkers, and multiple nearest-neighbor interactions among tumor, immune, and stromal cells that coordinate to influence overall survival rates in HGSC patients. In addition, SIO integrates IMC data with microdissected tumor and stromal transcriptomes from the same patients to identify novel signaling networks, which would lead to the discovery of novel survival rate-modulating mechanisms in HGSC patients.

Applications of CRISPR Genome Editing to Advance the Next Generation of Adoptive Cell Therapies for Cancer

Adoptive cell therapy (ACT) for cancer shows tremendous potential; however, several challenges preclude its widespread use. These include poor T-cell function in hostile tumor microenvironments, a lack of tumor-specific target antigens, and the high cost and poor scalability of cell therapy manufacturing. Creative genome-editing strategies are beginning to emerge to address each of these limitations, which has initiated the next generation of cell therapy products now entering clinical trials. CRISPR is at the forefront of this revolution, offering a simple and versatile platform for genetic engineering. This review provides a comprehensive overview of CRISPR applications that have advanced ACT. SIGNIFICANCE: The clinical impact of ACT for cancer can be expanded by implementing specific genetic modifications that enhance the potency, safety, and scalability of cellular products. Here we provide a detailed description of such genetic modifications, highlighting avenues to enhance the therapeutic efficacy and accessibility of ACT for cancer. Furthermore, we review high-throughput CRISPR genetic screens that have unveiled novel targets for cell therapy enhancement.

Pembrolizumab in vaginal and vulvar squamous cell carcinoma: a case series from a phase II basket trial

Vaginal and vulvar squamous cell carcinoma (SCC) are rare tumors that can be challenging to treat in the recurrent or metastatic setting. We present a case series of patients with vaginal or vulvar SCC who were treated with single-agent pembrolizumab as part of a phase II basket clinical trial to evaluate efficacy and safety. Two cases of recurrent and metastatic vaginal SCC, with multiple prior lines of systemic chemotherapy and radiation, received pembrolizumab. One patient had significant reduction (81%) in target tumor lesions prior to treatment discontinuation at cycle 10 following confirmed progression of disease with new metastatic lesions (stable disease by irRECIST criteria). In contrast, the other patient with vaginal SCC discontinued treatment after cycle 3 due to disease progression. Both patients had PD-L1 positive vaginal tumors and tolerated treatment well. One case of recurrent vulvar SCC with multiple surgical resections and prior progression on systemic carboplatin had a 30% reduction in her target tumor lesions following pembrolizumab treatment with a PD-L1 positive tumor. Treatment was discontinued for grade 3 mucositis after cycle 5. Pembrolizumab may provide some clinical benefit to some patients with vaginal or vulvar SCC and is overall safe to utilize in this population. Future studies are needed to evaluate the efficacy of pembrolizumab in these rare tumor types and to identify predictive biomarkers of response.

Abstract PO015: The impact of the tumor immune microenvironment on response to pembrolizumab in patients with microsatellite instability-high endometrial cancer

Introduction: Despite FDA approval of pembrolizumab in microsatellite instability-high (MSI-H) / mismatch repair deficient solid tumors, approximately half of patients with MSI-H endometrial cancer are treatment-refractory. Our unpublished analysis of MSI-H endometrial cancer samples from the Cancer Genome Atlas (TCGA) suggests the possibility of immunologically “hot” and “cold” tumor microenvironments (TME); these differences may explain variable treatment responses. We sought to evaluate MSI-H endometrial tumor samples to examine differences in the TME and identify transcriptomic signatures associated with response/resistance to pembrolizumab.

Methods: Archival tumor samples from MSI-H endometrial cancer patients treated at the University of Texas MD Anderson Cancer Center were obtained under an IRB-approved protocol. Tissue samples originating from patients who did not receive pembrolizumab treatment (“untreated cohort ”; n = 11) were submitted for RNA sequencing analysis (RNA-seq) to validate the TME heterogeneity observed in MSI-H samples of the TCGA dataset. Pre-treatment archival tumor samples (“treated cohort”; n = 23) from patients who were treated with pembrolizumab were collected and submitted for RNA-seq to identify predictive immuno-genomic signatures associated with treatment response.

Results: In the untreated cohort, there were observable differences in the transcriptomic profiles of the samples. Four samples were immunologically “hot” as evidenced by an abundance of pro-inflammatory immune cell infiltrate (CD8+ T-cells, B-cells, monocytes, and dendritic cells). Three samples had a paucity of pro-inflammatory immune cell infiltrate (“cold”) while 4 samples had intermediate amounts (“warm”). In the treated cohort, there were 14 responders, 7 non-responders, and 2 patients with unknown response. The 14 responders consisted of samples with “hot” (5/5; 100%), “cold” (6/8; 75%), and “warm” TMEs (3/8; 37.5%) while the 7 non-responders consisted of only “cold” (2/8; 25%) and “warm” (5/8; 62.5%) TME samples. We observed an enrichment of fibroblasts and endothelial cell transcriptomic signatures in the samples of the non-responders compared to responders (p = 0.018). In particular, there was a significantly higher gene expression of PAMR1, HHIP, and MMRN1 in the non-responders. Subdividing samples into complete response, partial response, and no response to pembrolizumab, we observed a trend of increasing enrichment of fibroblast and endothelial cell transcriptomic signatures as response decreased. Specifically, there was increasing expression of TAGLN (fibroblast gene) and other endothelial cell genes (EMCN, KDR, MMRN1, MYCT1, PEAR1, PTPRB, and TEK).

Conclusion: The TME composition appears to be heterogeneous among MSI-H endometrial cancer patients. Increased presence of fibroblasts and endothelial cells in the TME may contribute to innate resistance to pembrolizumab. Treatment aimed toward the reduction of these cellular subpopulations may improve sensitivity to PD-1 inhibitors. Future studies are needed to validate these findings.

Citation Format: Jeffrey A. How, Minghao Dao, Elizabeth Euscher, Melinda Yates, Weiyi Peng, Shrina D. Patel, Karen H. Lu, Patrick Hwu, Linghua Wang, Amir A. Jazaeri. The impact of the tumor immune microenvironment on response to pembrolizumab in patients with microsatellite instability-high endometrial cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO015.

Phase II study of pembrolizumab efficacy and safety in women with recurrent small cell neuroendocrine carcinoma of the lower genital tract

OBJECTIVE

To investigate the efficacy and safety of pembrolizumab in women with recurrent small cell neuroendocrine tumors of the lower genital tract.

METHODS

We conducted an open-label, investigator-initiated phase II basket trial of pembrolizumab 200 mg intravenously every 3 weeks in patients with rare tumors (ClinicalTrials.gov: NCT02721732). The trial had prespecified cohorts, including small cell malignancies of extrapulmonary origin. Eligibility criteria included disease progression during standard treatment in the 6 months before study enrollment. Patients were enrolled from February 2017 to February 2019. The primary endpoint was the proportion of patients alive without progression at 27 weeks. Response to pembrolizumab was evaluated every 9 weeks (3 cycles) with radiographic imaging.

RESULTS

Seven women with gynecologic extrapulmonary small cell carcinoma were enrolled, 6 with cervical and 1 with vulvar carcinoma. No patient was progression free at 27 weeks. At first radiologic assessment, 1 patient had stable disease, while 6 had progression. The single patient with stable disease at 6 weeks had disease progression at 14 weeks. The median progression-free interval was 2.1 months (range 0.8-3.3 months). Severe treatment-related adverse events (≥grade 3) were seen in 2 of 7 patients (29%); 1 patient had grade 3 asymptomatic elevation of serum alkaline phosphatase, and 1 had grade 3 asymptomatic elevation of serum alanine aminotransferase.

CONCLUSIONS

Pembrolizumab alone showed minimal activity in women with recurrent small cell neuroendocrine tumors of the lower genital tract. Treatment was well tolerated in the majority of study participants, and the rate of severe adverse events was low.

Abstract 3267: Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma

The role of immune checkpoint inhibitors (ICPIs) in ovarian cancer continues to be refined. The presence of intratumoral T cells in ovarian tumors correlates with improved survival and progression, suggesting that immune modulation, such as by ICPIs, may be beneficial. However, a better understanding of the immune effects following ICPI use, particularly in those with a long progression free survival, is needed. Thus, we used imaging mass cytometry (IMC) to compare the tumor immune landscape of patients with ovarian cancer before and after a CTLA4 immune checkpoint inhibitor treatment to determine the association between alterations in immune landscapes and progression free survival.

Fine needle biopsies were obtained from 8 patients with recurrent platinum-resistant ovarian carcinoma enrolled in a phase 2 randomized trial evaluating the efficacy of Tremelimumab and Durvalumab (CTLA4 and PDL1 checkpoint inhibitors, respectively) in recurrent ovarian cancer treatment. Each patient had a pre-treatment biopsy and on-treatment biopsy after 3 cycles of CTLA4 inhibitor therapy. Progression free time (PFS) was recorded with 3 patients with a long PFS (&gt;180 days) and 5 with short PFS (&lt;60 days).

Formalin fixed paraffin embedded (FFPE) tissue sections were stained for IMC analysis via Fluidigm protocol with 34 metal-tagged antibodies to detect various cell and immune related markers. The IMC data was obtained using the Fluidigm Helios CyTOF instrument and Hyperion Imaging System laser ablation module. A novel image informatics pipeline through Matlab was used to assess the image intensity of each marker and cell location.

Using the developed image informatics pipeline, cell types and locations were analyzed for 16 samples from 8 patients. In all patients, mean CD8+ T cell densities had an increased trend in on-treatment vs pre-treatment samples (205.6 v 129.9 cells/mm2, p=0.086). An analysis of cell location found that in all patients on-treatment, the mean number of CD8+ T cells adjacent to M2 macrophages increased significantly (0.09 v. 0.17 cells, p = 0.0460) as well as the mean number of CD8+ T cells adjacent to B7H4+ tumor cells (0.035 v. 0.01 cells, p = 0.046). Furthermore, patients with a long PFS had a significantly higher number of CD8+ cells neighboring B cells on-treatment than short PFS (0.12 v. 0.27 cells, p=0.028).

Using IMC and novel image informatics pipeline, we found that patients with recurrent ovarian cancer treated with Tremelimumab with a long PFS mounted a significant immune response compared to patients with a short PFS, with a higher number of CD8+ T cells neighboring B cells after treatment. For all patients, the immune landscape altered after treatment. To our knowledge, this is the first known use of IMC to demonstrate immune response in ovarian cancer following ICPI therapy. Overall, IMC and image informatics pipeline are robust tools that simultaneously analyze multiple biomarkers and spatial location of cells to better assess the tumor immune microenvironment and cellular interactions.

Citation Format: Han Cun, Emily M. Hinchcliff, Ying Zhu, Sammy Ferri-Borgogno, Rita Cheng, Jared K. Burks, Stephen T. Wong, Amir A. Jazaeri, Samuel C. Mok. Identification of a novel biomarker response in a prospective clinical trial of immune checkpoint blockade in recurrent ovarian carcinoma [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 3267.

Abstract CT163: Temsirolimus in combinaton with metformin in patients with advanced or refractory endometrial cancers

Purpose: There is limited success with chemotherapeutic agents in women with advanced or recurrent endometrial cancer. Dysregulation of the PI3K/RAS signaling pathways in endometrial cancer have been well documented. However, responses with mTOR inhibitor such as temsirolimus have been modest. Previously we have shown that metformin prevents temsirolimus-induced AKT activation. Therefore, we enrolled patients with advanced endometrial carcinoma in the expansion cohort of a phase I study of temsirolimus in combination with metformin. Methods: Patients with advanced endometrial cancer refractory to or relapse after standard therapies, ECOG performance status 0 or 1, and with significant organ function reserve were enrolled. Patients were administered intravenous temsirolimus 25mg weekly and oral metformin 2000 mg daily in 28-day cycles. Response was assessed every 2 cycles by clinical evaluation, tumor markers, and imaging per RECIST 1.1. All toxicities were graded using NCI CTCAE, version 4.0. Results: Forty patients were treated. Median age is 67 years (range, 33-78). Drug-related adverse events of any grade were reported in 34 patients. The most common toxicities were mucositis (n=13), AST increase (n=13), anorexia (n=12), diarrhea (n=12) and anemia (n=10). Eleven grade 3 drug-related adverse events were reported. They were anemia (n=2), thrombocytopenia (n=2), mucositis, fatigue, weight loss, hypokalemia, hypophosphatemia, AST increase and ALT increase (n=1 each). Of the 33 patients evaluable for response, objective response was seen in 2 (6%) patients. Both had partial response (PR) and were on the study for 8.7 and 18.2 months respectively. In addition, 13 (39%) patients had stable disease (SD), including 11 with SD ≥4 months, representing a clinical benefit rate of 39%. Molecular characterization of tumor was available for 35 patients. Thirty of 35 patients had molecular alterations in the PI3K and/or RAS pathway. Of the 30 patients, 1 had benign PI3K mutation and 4 were not evaluable for response. Of the remaining 25 patients with PI3K and/or KRAS pathway, 11 (44%) had either objective response or SD ≥4 months. Eighteen of them had molecular alteration only in the PI3K pathway. Seven of 18 (39%) had objective response or SD ≥4 months. Importantly, all 3 patients who had molecular alterations in both the PI3K and RAS pathway achieved SD ≥4 months, while 3 of the 4 patients with exclusive resistant KRAS mutation had progressive disease. Collectively, of the 13 patients with either objective response or SD ≥4 months, 11 (85%) patients had molecular alteration in the PI3K and/or RAS pathway. Conclusion: Temsirolimus in combination with metformin was well tolerated. Anti-tumor activity was seen in patients with advanced/refractory endometrial cancer, particularly in patients with molecular alterations in the PI3K and/or RAS pathway that warrants further study.

Citation Format: Aung Naing, Daniel Karp, Sarina A. Piha-Paul, Shubham Pant, Vivek Subbiah, Diane C. Bodurka, Siqing Fu, Amir A. Jazaeri, Shumei Kato, Kathleen Schmeler, Alpa Nick, Yali Yang, Fechukwu O. Akhmedzhanov, Senait Fessahaye, Jing Gong, Bettzy Stephen, Amber M. Johnson, Pamela T. Soliman, Anil K. Sood, Funda Meric-Bernstam, Karen H. Lu. Temsirolimus in combinaton with metformin in patients with advanced or refractory endometrial cancers [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 CT163.

Abstract 2510: High-depth whole genome sequencing of clinically-annotated high-grade serous ovarian cancers

Background: Prior molecular characterization efforts for high-grade serous ovarian cancer (HGSOC) were restricted to those who had upfront surgical debulking with variable treatment paradigms. Thus, we sought to examine molecular and cellular differences between clinically defined groups (tumor tissues from patients who had complete gross resection (CGR) versus those who were triaged to neoadjuvant chemotherapy (NACT) and experienced either excellent or poor response.

Methods: Tumor biopsies were collected from three patient groups managed under a systematic surgical algorithm: CGR after primary surgery (R0, n=10); poor tumor response to NACT (NACT-PR, n=10); excellent tumor response to NACT (NACT-ER, n=10). Primary and multiple metastatic tumor sites per each patient were obtained pre-treatment and subjected to comprehensive omics analyses including high-pass whole-genome (WGS) and targeted deep DNA sequencing.

Results: An average of 71 nonsynonymous somatic mutations from each sample for 75 samples with high-purity tumors (≥75%) by WGS were identified from each sample for the entire cohort. Fourteen ovarian-cancer-associated genes were found mutated in our patient cohort and, as expected, the most frequently mutated gene was TP53 in both primary and metastatic sites in all three groups. TP53 nonsense mutations were exclusively identified in the NACT-ER (36.0%) and NACT-PR groups (15.4%), while in the R0 group most TP53 mutations were missense mutations (62.5%). Nonsense mutations in CSMD3 and PIK3CA were exclusively identified in both primary and metastatic sites in the NACT-PR group. The most frequent copy number variations (CNVs) in the R0 were copy number gain/loss of CSMD3 (67%) and copy number loss of NF1 (54%) and CDK12 (50%) in both primary and metastatic sites. Interestingly, copy number losses of NF1 were significantly lower in the NACT groups (18%, p=0.002), especially in the NACT-PR (8%, p=0.0004), when compared to the R0 group (54%). We also identified significant less observation of chromothripsis-like patterns, and a significantly higher level of strong-binding neoantigens in the R0 than in the NACT groups.

Conclusions: Our findings using HGSOC samples obtained from patients treated on a prospective algorithm identified distinct molecular abnormalities, and could have prognostic and therapeutic implications for patients with HGSOC.

Citation Format: Sanghoon Lee, Li Zhao, Shannon N. Westin, Nicholas W. Bateman, Amir A. Jazaeri, Nicole D. Fleming, Karen H. Lu, Robert L. Coleman, Gordon B. Mills, Jianhua Zhang, Thomas P. Conrads, George L. Maxwell, P. Andrew Futreal, Anil K. Sood. High-depth whole genome sequencing of clinically-annotated high-grade serous ovarian cancers [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 2510.

Abstract 2941: Functional proteomic aberrations post-chemotherapy with paclitaxel and carboplatin in patients with advanced ovarian cancer

Background: High-grade serous ovarian cancer (HGSOC) remains the leading cause of death from gynecologic malignancies. Here, we examined tumoral proteome changes following neoadjuvant chemotherapy (NACT) to identify potential predictive and prognostic biomarkers of response to primary chemotherapy.

Methods: A total of 65 tissue specimens from 10 patients with advanced-stage HGSOC were collected from matched pre- and post-NACT (3 cycles of dose-dense paclitaxel and carboplatin). Protein expression was assessed using reverse-phase protein arrays (RPPA). All relative protein levels using 297 antibodies were normalized by the expression level of pre-treatment samples, and then protein expression alterations and functional analyses were performed by Reactome pathway analysis followed by statistical analysis.

Results: The protein expression patterns of samples tended to cluster according to the time point (pre- and post-treatment) by a non-supervised clustering analysis using all the proteins assessed in the RPPA panel. Five differentially expressed proteins among 239 proteins (adj. p&lt;0.1, log2FC≥1) were identified by RPPA. We identified XBP1, MYH11, and S100A4 as being upregulated and CCNB1 and TFRC were down-regulated post-treatment compared to pre-treatment. We also observed significant enrichment of specific functional and signaling pathways by pathway analysis; these included PI3K/AKT signaling, necrosis and programmed cell death (upregulated, p&lt;0.05, FDR&lt;1), and cell cycle and homology-directed repair (HDR) through homologous recombination repair and G2/M checkpoints (down-regulated, p&lt;0.02, FDR&lt;0.5) in post-treatment compared to pre-treatment. Interestingly, cell cycle, DNA damage, and G2 checkpoint pathways at post-treatment exhibited significantly lower pathway scores than pre-treatment.

Conclusion: Our findings identified significant proteomic alterations following NACT, and could provide insights into interval proteomic alterations following induction chemotherapy in advanced-stage ovarian cancer patients. These data present information to optimize future clinical trial designs for patients with ovarian cancer.

Citation Format: Sanghoon Lee, Li Zhao, Joseph Celestino, Kelly M. Rangel, Richard A. Hajek, Mark S. Kim, Sara E. Sharafi, Jinsong Liu, Nicole D. Fleming, Karen H. Lu, Jianhua Zhang, P. Andrew Futreal, Gordon B. Mills, Shannon N. Westin, Anil K. Sood, Amir A. Jazaeri, Robert L. Coleman. Functional proteomic aberrations post-chemotherapy with paclitaxel and carboplatin in patients with advanced ovarian cancer [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 2941.

Present-day management of uterine leiomyosarcoma: Evaluation of treatment sequencing and other prognostic factors

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Background: Uterine leiomyosarcoma (ULMS) is a rare tumor with limited therapeutic options and no clearly established best treatment sequence strategy. Methods: Women with ULMS between 2013-2018 were identified. Clinical data was collected; descriptive statistics were performed and predictors of overall survival (OS) and progression free survival (PFS) were analyzed. Results: 189 patients were included. Median age was 53 (20-84), 91% had grade 3 tumors and 51.3% had stage IB disease. 50% underwent surgery followed by chemotherapy (n = 94, 49.7%) and 37% had surgery only (n = 70). 49 patients retained their ovaries; there was no difference in OS by oophorectomy status (p = 0.71). Estrogen and progesterone receptor (ER/PR) status, positive in 41% and 33% respectively, was not independently associated with OS (p = 0.23, p = 0.12) nor did it impact OS among those with oophorectomy and without (p = 0.70). The most common adjuvant therapy regimens were gemcitabine/docetaxel (gem/doce, 64%) or ifosphamide/doxorubicin (ifos/doxo, 19%). There were no differences in the regimens prescribed by physician specialty (gynecologic oncology vs other, p = 0.21). 147 patients (78%) experienced a recurrence or progression. For the 73 patients who received gem/doce as adjuvant therapy, 58.9% recurred and were most commonly treated with doxo containing regimens (67%). Of the 22 patients treated with ifos/doxo, only 3 recurred and each received a different second line regimen. For those not treated with adjuvant therapy (70 patients), 58.2% recurred and were treated with gem/doce (62%) and ifos/doxo (24%). In early stage patients, the majority received surgery only (45%) or surgery followed by chemotherapy (44%). There was no difference in OS in those who received adjuvant therapy and those who did not (p = 0.39). 46 (24%) had molecular testing and 37 had identified mutations. The most common mutation found was P53 (n = 25, 54%) followed by RB1 (8, 17%), PTEN (7, 15%), and BRCA (2, 4%). Conclusions: Recurrence occurred in 78% of patient despite many women undergoing adjuvant therapy after surgery. Oophorectomy did not influence OS, even though 41% of tumors were ER positive. The sequence of treatment was not associated with OS, however, the risk for recurrence in patient treated with adjuvant Ifos/Doxo was 14% compared to 59% in gem/doce. This finding warrants additional evaluation to determine the optimal adjuvant therapy for these women.

Molecular Analysis of Clinically Defined Subsets of High-Grade Serous Ovarian Cancer

The diversity and heterogeneity within high-grade serous ovarian cancer (HGSC), which is the most lethal gynecologic malignancy, is not well understood. Here, we perform comprehensive multi-platform omics analyses, including integrated analysis, and immune monitoring on primary and metastatic sites from highly clinically annotated HGSC samples based on a laparoscopic triage algorithm from patients who underwent complete gross resection (R0) or received neoadjuvant chemotherapy (NACT) with excellent or poor response. We identify significant distinct molecular abnormalities and cellular changes and immune cell repertoire alterations between the groups, including a higher rate of NF1 copy number loss, and reduced chromothripsis-like patterns, higher levels of strong-binding neoantigens, and a higher number of infiltrated T cells in the R0 versus the NACT groups.

Phase II evaluation of nivolumab in the treatment of persistent or recurrent cervical cancer (NCT02257528/NRG-GY002)

PURPOSE

Patients with persistent/recurrent cervical cancer following platinum-based chemotherapy have limited therapeutic options. The Gynecologic-Oncology-Group conducted a phase II trial to assess efficacy and tolerability of nivolumab, an immune checkpoint inhibitor, in persistent/recurrent cervical carcinoma.

PATIENTS AND METHODS

Key eligibility criteria included persistent/recurrent cervical cancer, failure of prior systemic therapy and ECOG PS 0-1. Nivolumab 3 mg/kg was given IV every 2 wk. until disease progression or intolerable toxicity. Response was assessed every 8 wk. for 6 months and every 12 wk. thereafter. The primary endpoints were objective response as assessed by RECIST 1.1. The study used a 2-stage group sequential design. PD-L1 expression was evaluated in tumor specimens by immunohistochemistry (IHC) using a combined-positive-score (CPS) cutoff of ≥1%.

RESULTS

Of 26 enrolled patients with persistent/recurrent cervical cancer, 25 were evaluable for response/toxicity with a median age of 45. 36% had ECOG PS of 1, and 100% had received one prior systemic chemotherapy regimen. PD-L1 expression (≥1%) was identified in 77.3% of tumor samples. As of 03/05/19, all patients were off study treatment; median follow-up for survival status was 32 months (range, 2-41.5). There were 21 (84%) patients with a treatment-related adverse event (TRAE) and most were grades 1-2. Six (24%) patients had grade 3 TRAEs with 1 discontinuing nivolumab due to hepatic toxicity. No grade 5 TRAEs occurred, and 2 patients had grade 4 TRAEs. One confirmed partial response (4%; 90% CI, 0.4%-22.9%), duration of response 3.8 months. Thirty-six percent of patients had stable disease (SD) (9/25; 90% CI, 20.2%-54.4%); the median duration of SD was 5.7 months (range, 3.5-12.7). Estimated PFS and OS at 6 months were 16% and 78.4%, respectively.

CONCLUSION

Single agent nivolumab exhibited low antitumor activity and an acceptable safety profile in patients with persistent/recurrent cervical cancer previously treated with platinum-based chemotherapy.

Potential clinical application of tumor-infiltrating lymphocyte therapy for ovarian epithelial cancer prior or post-resistance to chemotherapy

BACKGROUND

Immunotherapy has become a powerful treatment option for several solid tumor types. The presence of tumor-infiltrating lymphocytes (TIL) is correlated with better prognosis in ovarian cancer, pointing at the possibility to benefit from harnessing their anti-tumor activity. This preclinical study explores the feasibility of adoptive cell therapy (ACT) with TIL using an improved culture method.

METHODS

TIL from high-grade serous ovarian cancer were cultured using a combination of IL-2 with agonistic antibodies targeting 4-1BB and CD3. The cells were phenotyped using flow cytometry in the fresh tissue and after expansion. Tumor reactivity was assessed against HLA-matched ovarian cancer cell lines via IFN-γ ELISPOT.

RESULTS

Ovarian cancer is highly infiltrated with CD8⁺ TIL that are preferentially and robustly expanded with the addition of the agonistic antibodies. With a 95% success rate, the TIL are grown to ≥ 100 × 10⁶ cells in 2-3 weeks without over differentiation. In addition, the CD8⁺ TIL grown with this method showed HLA-restricted tumor recognition.

CONCLUSIONS

These results indicate the viability of TIL ACT for refractory ovarian cancer by allowing for the large expansion of anti-tumor TIL in a short time and consistent manner.

B-cell acute lymphoblastic leukemia/lymphoma in relapse presenting as a cervical mass: A case report and review of literature

The involvement of the cervix as a site of relapse for hematologic malignancies is rare. We herein present a case of relapsed B-cell Acute Lymphoblastic Leukemia/Lymphoma (ALL) mimicking advanced cervical cancer. The patient is a 61-year-old female with history B-cell ALL and had multiple relapses confined to the bone marrow and had received several different chemotherapy regimens. She presented with lower abdominal pain after the end of her last cycle for which an MRI abdomen and pelvis was done and it showed the presence of an asymmetrical cervical mass. Further imaging included a PET-CT showing the presence of hypermetabolic cervical mass with left pelvic and retroperitoneal lymph node involvement. She underwent a biopsy of 3 distinct lesions in the cervix and vagina and a diagnosis of relapsed B-cell ALL was confirmed in two out of the three specimens.

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The cervix as a site of relapse for hematologic malignancies is rare.

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History of leukemia should raise suspicion of extra-medullary involvement.

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Imaging along with histologic specimen provide a better diagnosis.

Chemotherapy-Induced Distal Enhancers Drive Transcriptional Programs to Maintain the Chemoresistant State in Ovarian Cancer

Chemoresistance is driven by unique regulatory networks in the genome that are distinct from those necessary for cancer development. Here, we investigate the contribution of enhancer elements to cisplatin resistance in ovarian cancers. Epigenome profiling of multiple cellular models of chemoresistance identified unique sets of distal enhancers, super-enhancers (SE), and their gene targets that coordinate and maintain the transcriptional program of the platinum-resistant state in ovarian cancer. Pharmacologic inhibition of distal enhancers through small-molecule epigenetic inhibitors suppressed the expression of their target genes and restored cisplatin sensitivity in vitro and in vivo. In addition to known drivers of chemoresistance, our findings identified SOX9 as a critical SE-regulated transcription factor that plays a critical role in acquiring and maintaining the chemoresistant state in ovarian cancer. The approach and findings presented here suggest that integrative analysis of epigenome and transcriptional programs could identify targetable key drivers of chemoresistance in cancers. SIGNIFICANCE: Integrative genome-wide epigenomic and transcriptomic analyses of platinum-sensitive and -resistant ovarian lines identify key distal regulatory regions and associated master regulator transcription factors that can be targeted by small-molecule epigenetic inhibitors.