Facts and Hopes in Neoadjuvant Immunotherapy: Current Approvals and Emerging Evidence

In 2021 and 2022, two immune checkpoint inhibitors received FDA approval in the neoadjuvant setting for the treatment of early-stage triple negative breast cancer (TNBC) and non-small cell lung cancer (NSCLC). Several more studies have since indicated the benefits, and challenges, of administering neoadjuvant immunotherapy prior to definitive surgery in the gastrointestinal, head and neck, and cutaneous realms. In addition, numerous ongoing phase II and phase III trials are investigating outcomes of neoadjuvant immune treatment in early-stage disease. As such, it is anticipated that more immune checkpoint inhibitors will receive approval for various neoadjuvant indications in the next several years. Medical oncologists, surgeons, and other providers in a multidisciplinary cancer care team will be presented with alternate treatment paradigms and clinical decisions regarding upfront surgery versus neoadjuvant treatment. Here, we describe the current evidence supporting use of immune checkpoint inhibitors for neoadjuvant treatment, ongoing studies, and clinical considerations of this treatment approach.

Tumor cells fail to present MHC-II-restricted epitopes derived from oncogenes to CD4+ T cells

CD4+ T cells play a critical role in antitumor immunity via recognition of peptide antigens presented on MHC class II (MHC-II). Although some solid cancers can be induced to express MHC-II, the extent to which this enables direct recognition by tumor-specific CD4+ T cells is unclear. We isolated and characterized T cell antigen receptors (TCRs) from naturally primed CD4+ T cells specific for 2 oncoproteins, HPV-16 E6 and the activating KRASG12V mutation, from patients with head and neck squamous cell carcinoma and pancreatic ductal adenocarcinoma, respectively, and determined their ability to recognize autologous or human leukocyte antigen-matched antigen-expressing tumor cells. We found in both cases that the TCRs were capable of recognizing peptide-loaded target cells expressing the relevant MHC-II or B cell antigen-presenting cells (APCs) when the antigens were endogenously expressed and directed to the endosomal pathway but failed to recognize tumor cells expressing the source protein even after induction of surface MHC-II expression by IFN-γ or transduction with CIITA. These results suggest that priming and functional recognition of both a nuclear (E6) and a membrane-associated (KRAS) oncoprotein are predominantly confined to crosspresenting APCs rather than via direct recognition of tumor cells induced to express MHC-II.

Interim safety and efficacy results from a phase 1 study of NT219 in adults with advanced solid tumors

3096

Background: NT219 is a small molecule, effecting IRS1/2 degradation and inhibiting STAT3 phosphorylation. IRS1/2 and STAT3 are major signaling junctions regulated by various oncogenes, altered during epithelial to mesenchymal transition (EMT) and drug resistance, and play an important role in the tumor and its microenvironment. A Phase 1/2 study (NCT04474470) includes a dose escalation of NT219 administered weekly for the treatment of relapsed and/or refractory cancer patients. Methods: In the dose escalation part of the study involving a conventional 3+3 design, patients with recurrent and/or metastatic solid tumors were administered intravenously with NT219 at 3, 6, 12 and 24mg/kg. Safety was assessed according to CTCAE v5 and anti-tumor activity was assessed by the investigators according to RECISTv1.1 using CT/MRI. The primary objectives of this part of the study are to evaluate safety, tolerability, PK and determine the recommended Phase 2 dose (RP2D). The study includes evaluation of potential biomarkers including measurements of STAT3, IRS1/2 phosphorylation, and TILs in biopsy specimens. Results: As of data cutoff date of February 8, 2022, a total of 13 patients were enrolled to 4 NT219 dose levels (3 - 24mg/kg) in the dose escalation phase, of which 11 were evaluable for dose limiting toxicity (DLT) determination, including 4 with colorectal cancer (CRC), 2 with pancreatic cancer, 2 with breast cancer, and one of each of the following cancers: gastroesophageal junction (GEJ), esophageal, appendiceal, papillary thyroid, and mesothelioma. Median number of prior treatment regimens for metastatic disease was 4 (2-11). Six Grade 3 adverse events (AEs) were observed, including alkaline phosphatase increase, aspartate aminotransferase increase, toxic encephalopathy, worsening back pain, abdominopelvic ascites, closed displaced fracture of right femoral neck, with the first 2 considered as possibly related to NT219. No Grade 4 AEs or treatment related deaths were reported. For the 11 evaluable patients, best overall response included one confirmed PR (GEJ patient, 5.5 months duration of response), and 3 SD (3 of 4 CRC patients; duration of 5.2, 4, and 2 months with ongoing follow up) with two patients awaiting follow up MRI/CT scans. As of the cutoff date, 9/11 patients that completed the DLT period are either on treatment or in follow up (range 1.1 to 14.7 months). Conclusions: Interim analysis of safety results obtained in 4 NT219 dose levels found NT219 to be well tolerated without DLTs in advanced cancer patients. The observed durable PR in a GEJ patient and SDs in 3 CRC patients are an encouraging initial signal of efficacy. Combination treatment of cetuximab with escalating NT219 doses in patients with recurrent/metastatic CRC and squamous cell carcinoma of the head and neck (SCCHN) has begun. An expansion cohort in patients with recurrent/metastatic SCCHN will be initiated at the conclusion of this part. Clinical trial information: NCT04474470.

A phase 1 multiple-ascending dose study to evaluate the safety and tolerability of XmAb23104 (PD-1 x ICOS) in subjects with selected advanced solid tumors (DUET-3)

2604

Background: XmAb23104 is a bispecific antibody targeting T cells that simultaneously express PD-1, an immune checkpoint, and ICOS, a costimulatory molecule expressed after T cell activation. DUET-3 is a Phase 1, first-in-human, dose-escalation and expansion study in subjects with advanced solid tumors, designed to assess safety, tolerability and to identify the maximum tolerated dose (MTD) of XmAb23104. Secondary objectives are to assess pharmacokinetics (PK), immunogenicity, and preliminary anti-tumor activity. We report preliminary data from the completed dose-escalation phase. Methods: A 3+3 monotherapy dose escalation with 9 dose levels from 0.002 to 15 mg/kg has been completed. Subjects with measurable disease who progressed on prior standard therapy were eligible. A minimum 6-week washout from prior pembrolizumab was required. XmAb23104 was administered biweekly and RECIST 1.1 assessment was performed every 8 weeks. Results: Sixty-two subjects were treated in escalation at doses up to 15 mg/kg; no dose-limiting toxicities were observed and an MTD was not reached. These subjects had advanced disease, 92% were Stage IV at screening, the median number of prior therapies was 3, and 37% had previous checkpoint therapy. Thirty-seven subjects (59.7%) experienced a treatment-related adverse event (TRAE); the most common were diarrhea (9.7%), decreased appetite (9.7%), and fatigue (9.7%). The majority of TRAEs were Grades 1 or 2, with 6 subjects (9.7%) having a Grade 3 or higher TRAE. Thirteen immunotherapy-related adverse events (irAEs) occurred in 8 subjects; no individual irAE occurred in more than 1 subject. Most irAEs were mild (Grades 1 and 2) with 1 Grade 3 pruritus and 1 asymptomatic Grade 4 lipase elevation. Partial responses were observed in 3 subjects (sarcoma; prior PD-1 head and neck squamous cell carcinoma [HNSCC] and renal cell carcinoma [RCC]), and stable disease > 12 months was observed in 2 subjects with colorectal cancer (CRC; 1 MSS and 1 MSI-H). A dose of 10 mg/kg was selected after consideration of PK, safety, and clinical activity data in consultation with the investigators and continues to be evaluated in the expansion part of the study. Conclusions: The dose escalation part of this study indicates XmAb23104 was generally well tolerated at doses up to 15 mg/kg and has shown clinical activity in subjects with advanced solid tumors. CTLA4 blockade has been found to increase the frequency of ICOS-expressing T cells in prostate cancer, bladder cancer, melanoma, and hepatocellular cancer (Chen, 2009; Liakou, 2008; Wei, 2017) and may be applicable to other immunogenic tumor types. XmAb23104 is currently being studied alone or in combination with ipilimumab in expansion in non-squamous non-small cell lung carcinoma, melanoma, CRC, undifferentiated pleomorphic sarcoma, HNSCC, and RCC. Clinical trial information: NCT03752398.

Use of clinical RNA-sequencing in the detection of actionable fusions compared to DNA-sequencing alone

3077

Background: While targeted DNA-seq can detect clinically actionable fusions in tumor tissue samples, technical and analytical challenges may give rise to false negatives. RNA-based, whole-exome sequencing provides a complementary method for fusion detection, and may improve the identification of actionable variants. In this study, we quantify this benefit using a large, real-world clinical dataset to assess actionable fusions detected from RNA in conjunction with DNA profiling. Methods: Using the Tempus Research Database, we retrospectively analyzed a de-identified dataset of ̃80K samples (77.4K patients) profiled with the Tempus xT assay (both DNA-seq with fusion detection in 21 genes and whole exome capture RNA-seq). Only patients that had successful RNA- and DNA-seq were included. Fusions were detected using the Tempus bioinformatic and clinical workflow. Candidate fusions were filtered based on read support thresholds, fusion annotation ( i.e., breakpoints, reading frame, conserved domains), and manual review. OncoKB was used to select fusion alterations in levels 1 and 2 and to identify those indication-matched to targeted therapies. Results: We identified 2118 level 1 and 2 fusion events across 1945 patients across 20 different cancer types. Most fusions were observed in non-small cell lung cancer (NSCLC) (25%) and biliary cancer (9%) samples. Of the 2118 fusion events, 29.1% (616) were detected only through RNA-seq while 4.8% (101) of the events were identifiable only through DNA-seq. Notably, 69.4% of fusions in low-grade glioma and 58.2% in sarcomas were detected only by RNA-seq. When evaluating specific gene fusion events, RNA-seq consistently improved the detection of fusions compared to DNA-seq alone (Table) across all cancer types. A total of 1106 fusions were classified as targetable by OncoKB indication-matched therapies with 19% (214) of these identifiable through RNA-seq alone, 5% (54) by DNA-seq alone, and 76% (838) identifiable through RNA- and DNA-seq. Overall, fusions identified through RNA-seq alone led to a 24% increase in the number of patients who were eligible to receive matched therapies (214 / 892). This included imatinib for patients with CML/BLCL (69.8%), crizotinib for NSCLC (40.3%) and entrectinib for NTRK and ROS1 fusions (32.5%). Conclusions: The addition of RNA-seq to DNA-seq significantly increased the detection of fusion events and ability to match patients to targeted therapies. Results support consideration of combined RNA-DNA-seq for standard-of-care fusion calling. [Table: see text]

Intralesional SD-101 in Combination with Pembrolizumab in Anti-PD-1 Treatment-Naïve Head and Neck Squamous Cell Carcinoma: Results from a Multicenter, Phase II Trial

PURPOSE

To determine whether SD-101, a Toll-like receptor 9 agonist, potentiates the antitumor activity of anti-PD-1 antibodies in patients with anti-PD-1/PD-L1 naïve, recurrent/metastatic head and neck squamous cell carcinoma (HNSCC).

PATIENTS AND METHODS

Patients with PD-1 Ab-naïve HNSCC received either 2 mg SD-101 injected in one to four lesions or 8 mg SD-101 injected into a single lesion weekly × 4 doses then every 3 weeks × 7 doses. Pembrolizumab was administered at 200 mg every 3 weeks.

RESULTS

A total of 28 patients received 2 mg and 23 received 8 mg per injection, respectively. A total of 76% of patients had received prior systemic therapy. Combined positive score was ≥1 to < 20 in 35 patients (70%) and ≥ 20 in 15 patients (30%) of 50 patients with available data. There were 12 patients with grade ≥3 treatment-related adverse events (24%), and no treatment-related deaths. The objective response rate was 24% including 2 complete and 10 partial responses. The median duration of response was 7.0 [95% confidence interval (CI): 2.1-11.1] months. The response rate was higher in human papillomavirus-positive (HPV+) patients (44%, N = 16). Responses were not associated with PD-L1 expression levels or IFNγ-related gene expression at baseline. Responses were observed both in injected (32%) and in noninjected lesions (29%). Progression-free and overall survival at 9 months were 19.0% (95% CI: 9.1-31.7) and 64.7% (95% CI: 45.3-78.7), respectively.

CONCLUSIONS

SD-101 combined with pembrolizumab induced objective responses, especially in HPV+ tumors, which were frequently associated with increased intratumoral inflammation and effector immune cell activity.

Safety and Efficacy of Pembrolizumab in Combination with Acalabrutinib in Advanced Head and Neck Squamous Cell Carcinoma: Phase 2 Proof-of-Concept Study

PURPOSE

Programmed cell death-1 (PD-1) receptor inhibitors have shown efficacy in head and neck squamous cell carcinoma (HNSCC), but treatment failure or secondary resistance occurs in most patients. In preclinical murine carcinoma models, inhibition of Bruton's tyrosine kinase (BTK) induces myeloid cell reprogramming that subsequently bolsters CD8+ T cell responses, resulting in enhanced antitumor activity. This phase 2, multicenter, open-label, randomized study evaluated pembrolizumab (anti-PD-1 monoclonal antibody) plus acalabrutinib (BTK inhibitor) in recurrent or metastatic HNSCC.

PATIENTS AND METHODS

Patients received pembrolizumab 200 mg intravenously every 3 weeks, alone or in combination with acalabrutinib 100 mg orally twice daily. Safety and overall response rate (ORR) were co-primary objectives. The secondary objectives were progression-free survival (PFS) and overall survival.

RESULTS

Seventy-six patients were evaluated (pembrolizumab, n = 39; pembrolizumab + acalabrutinib, n = 37). Higher frequencies of grade 3-4 treatment-emergent adverse events (AE; 65% vs. 39%) and serious AEs (68% vs. 31%) were observed with combination therapy versus monotherapy. ORR was 18% with monotherapy versus 14% with combination therapy. Median PFS was 2.7 [95% confidence interval (CI), 1.4-6.8] months in the combination arm and 1.7 (95% CI, 1.4-4.0) months in the monotherapy arm. The study was terminated due to lack of clinical benefit with combination treatment. To assess how tumor immune contexture was affected by therapy in patients with pre- and post-treatment biopsies, spatial proteomic analyses were conducted that revealed a trend toward increased CD45+ leukocyte infiltration of tumors from baseline at day 43 with pembrolizumab (monotherapy, n = 5; combination, n = 2), which appeared to be higher in combination-treated patients; however, definitive conclusions could not be drawn due to limited sample size.

CONCLUSIONS

Despite lack of clinical efficacy, immune subset analyses suggest that there are additive effects of this combination; however, the associated toxicity limits the feasibility of combination treatment with pembrolizumab and acalabrutinib in patients with recurrent or metastatic HNSCC.

Abstract P185: Preliminary antitumor activity of MCLA-158, an IgG1 bispecific antibody targeting EGFR and LGR5, in advanced head and neck squamous cell carcinoma

In the expansion part of an ongoing phase 1 study, MCLA-158 is being investigated at the recommended phase 2 dose (RP2D) in patients (pts) with advanced solid tumors, including head and neck squamous cell carcinoma (HNSCC). Epidermal growth factor receptor (EGFR) and WNT signaling are known oncogenic and mitogenic drivers in several cancers, including HNSCC. MCLA-158 is a human common light chain IgG1 bispecific antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) activity. It targets EGFR and the leucine-rich, repeat-containing, G-protein coupled receptor 5 (LGR5), a transmembrane receptor associated with tumor initiating cells, particularly cancer stem cells. Potent antitumor activity was seen with MCLA-158 in pt-derived HNSCC xenograft models. The RP2D of MCLA-158 was determined to be 1500 mg every 2 weeks (q2w), with 4-week cycles, during the dose escalation part of the study, based on safety, PK and receptor occupancy prediction. A maximum tolerated dose was not reached. The primary objective of the expansion part is to characterize the safety and tolerability of single-agent MCLA-158 and confirm the RP2D. Secondary objectives include assessment of antitumor activity (investigator-assessed overall response rate [ORR] per RECIST 1.1 and duration of response). Key eligibility criteria include prior exposure to standard therapy, ECOG performance status (PS) 0-1, measurable disease (RECIST 1.1), and availability of a baseline tumor biopsy. At the interim data cutoff date of 15 June 2021, 7 pts with advanced recurrent/metastatic HNSCC were enrolled and treated in the expansion phase. Median age was 63 years (range 50-74), ECOG PS 0/1: 2/5. Primary tumor locations were oropharynx (2 pts), hypopharynx (1 pts), larynx (3 pts), and unknown primary (1 pt). All pts had a histology of squamous cell carcinoma. Prior treatment included platinum-based chemotherapy in all pts, and anti-PD-1/PD-L1 in 6 pts. No pts received prior cetuximab. A median of 3 treatment cycles (range 1-8) were administered to the 7 pts, 4 of whom were continuing with therapy at the cutoff. Of the 5 pts who had a postbaseline assessment, 2 had confirmed partial responses (5+ and 8 cycles initiated), and 2 pts had stable disease (reduction in the sum of target lesions of 7% and 17%; 4+ and 5 cycles initiated, respectively). Scheduled first postbaseline tumor assessments for 2 pts occurred after the data cutoff date. Among 26 pts who were treated at the RP2D in the dose escalation and expansion cohorts, the most frequent adverse events regardless of causality (all grades/grade 3) were infusion-related reactions (73%/8%), rash (39%/0%), asthenia (35%/4%), decreased appetite (27%/4%), nausea (27%/4%), and acneiform dermatitis (23%/4%). There were no treatment-related grade 4 or 5 adverse events. In conclusion, MCLA-158 shows promising signs of antitumor activity in pretreated HNSCC, and a well-tolerated and favorable safety profile.

Citation Format: Antoine Hollebecque, Irene Brana, Lara Iglesias, Caroline Even, Kato Shumei, Marc Díez García, Mateo Bover, Patricia Martin-Romano, Rocio Garcia-Carbonero, Guillen Argilés, Josep Tabernero, Rajan Khanna, Viktoriya Stalbovskaya, Jeroen Lammerts van Bueren, Kees Bol, Mohamed Bekradda, Andrew Joe, Ernesto Wasserman, Ezra E.W. Cohen. Preliminary antitumor activity of MCLA-158, an IgG1 bispecific antibody targeting EGFR and LGR5, in advanced head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P185.

A phase II open label, single arm study to evaluate the efficacy of pembrolizumab for leukoplakia

TPS10606

Background: The presence of pre-cancerous oral lesions such as leukoplakia or erythroleukoplakia are known risk factors for the development of squamous cell carcinoma of the head and neck (SCCHN), however preventative agents have not yet shown clinical benefit. The risk of malignant transformation varies but has been quoted as high as 36% in some studies. While the primary mode of treatment of these lesions is largely surgical, recurrence rates are high. Pembrolizumab is a potent and selective humanized monoclonal antibody that is designed to directly block the interaction between PD-1 and PD-L1 (as well as PD-L2) that is currently FDA-approved for treatment of SCCHN. We have hypothesized that the treatment of oral premalignant lesions with pembrolizumab would be an effective and well-tolerated strategy to prevent transformation to invasive cancer. Methods: This study is an open-label, phase II study that will accrue 26 patients with leukoplakia, erythroleukoplakia, or proliferative verrucous leukoplakia with documented moderate to severe dysplasia or carcinoma in situ to be treated with pembrolizumab 200mg every 3 weeks for a total of 6 months. Patients must have visible and measurable lesions that will be both photographed and measured in two dimensions at each visit from the start of treatment until 12 months post-enrollment. Biopsies will be required at diagnosis and following the final treatment, with an optional biopsy following cycle 2 and at progression of disease. Major exclusion criteria include patients with mild dysplasia or hyperplasia, prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks of Day 1 of study, or patients with a known additional malignancy that is active. Patients will also be excluded if they have received anti-PD-1, anti-PD-L1 or anti-PD-L2 treatments in the past. The primary objective is clinical response rate at 6 months, and will be quantified as the percentage of patients with a complete response (CR) and partial response (PR) at 6 months. A CR is defined as complete resolution by visual inspection for 4 weeks of more and a PR is defined as 50% or greater reduction of the product of the 2 dimensions of a single lesions or the sum of all lesions. Progressive disease (PD) is defined as unequivocal increase (greater than or equal to 5mm in one dimension and greater than 20% increase) or the development of new lesions. Secondary objectives will include histologic response rate at 6 months, change in clinical impression based on photographs, clinical response rate at 9 and 12 months, and toxicity. Additional exploratory objectives will include PD-L1 expression in leukoplakia lesions as well as p16 expression, presence of tumor infiltrating lymphocytes, and immunohistochemical as well as RNA sequencing gene expression profiling which may allow for the identification of novel biomarkers. Enrollment began in June 2019 and is ongoing. Clinical trial information: NCT03603223 .

Transoral robotic surgery for human papillomavirus-associated oropharynx squamous cell carcinoma: Recurrence and survival in the Veterans Affairs health system

6054

Background: Most transoral robotic surgery (TORS) literature comes from single and multi-institutional studies at tertiary-care academic intuitions. Long-term outcomes for patients with HPV-mediated oropharyngeal squamous cell carcinoma (HPV-OPSCC) treated with upfront TORS in other hospital settings across the United States are largely unknown. We present long-term recurrence and survival outcomes from a novel Veterans Health Administration (VHA) longitudinal dataset that includes patient-level data. Methods: Retrospective analysis of national VHA patients with p16-positive OPSCC diagnosed between January 2010 and December 2016, treated with TORS primary tumor resection with neck dissection. Outcome measures included: Cancer-specific survival (CSS), progression free survival (PFS), overall survival (OS), recurrence, extranodal extension (ENE), positive surgical margin (PSM), and adjuvant therapy regimen. Results: One hundred sixty-one patients were included of whom 29 (18%) were low-risk [0-1 metastatic lymph nodes, negative margins]; 45 (28%) intermediate-risk [close surgical margins, 2 to 4 metastatic nodes, LVI or PNI, pathologic T3 or T4 tumor]; and 87 (54%) high-risk [PSM, ENE, and/or ≥ 5 metastatic nodes]. ENE was present in 41% of cases and 24% of cases had positive surgical margins. Median follow-up was 5.6 years (95% CI 3.0-9.3). The 5-year CSS rates for low, intermediate, and high-risk groups were: 100%, 90.0% (95% CI 75.4-96.1%), and 88.7% (78.3-94.2%). On univariable analysis, pathologic factors associated with inferior CSS were: pT3-T4 tumor category (HR 3.81, 95% CI 1.31-11; p = 0.01), presence of more than four metastatic lymph nodes (HR 3.41, 95% CI 1.20-11; p = 0.02), and ENE (HR 3.53, 95% CI 1.06-12; p = 0.04). Close or PSM were not associated with CSS (HR 0.67, 95% CI 0.21 – 2.14; p = 0.50). In the low-risk group, 48% avoided adjuvant therapy and although there were five recurrences, none died from cancer. The intermediate-risk group was treated with adjuvant radiation in 64% of cases, and chemoradiation in 29% of cases; and there were five locoregional recurrences and three distant recurrences. Adjuvant chemoradiation was used in 68% of high-risk cases. Of the seven total patients with distant recurrences, six died of their disease. Conclusions: Our findings in this national cohort of Veterans with HPV-OPSCC demonstrate that TORS followed by adjuvant therapy yields favorable survival outcomes. Tumor-category, ENE, and more than four nodal metastases were the strongest adverse features in our data, and surgical margins did not have a significant impact on survival. Further investigations with large cohorts and prospective clinical trials are needed to elucidate the true oncologic implications of high-risk features and to identify patients best suited for de-intensified treatment.

A phase 1b study of personalized neoantigen vaccine plus pembrolizumab in adults with advanced cancer

2615

Background: Neoantigens (NeoAg) are key targets for personalized immunotherapy but efficient methods for their systematic identification and therapeutic targeting remain elusive. We developed a methodology to reliably identify and verify somatic alteration-derived neoantigens based on natural T cell responses against them which formed the basis of an individualized therapeutic vaccine strategy. Methods: This is a phase Ib study to assess the immunogenicity, safety and early clinical activity of personalized synthetic long peptides (PSLP) cancer vaccines in combination with pembrolizumab for patients with treatment refractory metastatic solid tumors or PSLP vaccine alone as an adjuvant treatment with patients with no evidence of disease (NED) that incorporates patient-specific NeoAg identified by an HLA-agnostic, functional T-cell assay (see table). Results: At the time of data cutoff, a total of 5 patients had been treated on ARM-A, 5 patients on ARM-C and 2 patients on ARM-D. AES possibly attributed to personalized vaccine (PSLP), or pembrolizumab, or both include: Grade 1: Arthralgia (1); Diarrhea (1); Fever (4); Fatigue (7); Generalized muscle weakness (1); Headache (2); Nausea (1); Confusion (1); Injection site reaction (5); Rash maculo-papular (3); Flu like symptoms (5); Myalgia (1); and Grade 2: Diarrhea (1); Fatigue (1); Hyperhidrosis (1); Hypothyroidism (1); Injection site reaction (1); Proteinuria (1); Renal and Urinary – other (1); and Grade 3: Colitis (1). For the 9 patients with at least 1 radiographic assessment at the time of analysis 6 had a best response of stable disease (SD) and 3 had progressive disease (PD). Immune monitoring of peripheral blood specimens consistently demonstrated that NeoAg-specific T cell responses were enhanced following administration of PSLP vaccine. On-treatment biopsies demonstrated immune-editing with the variant allele frequency of targeted mutations decreasing following administration of the PSLP vaccine. Conclusions: Taken together, these data meet the trial primary endpoint by demonstrating PSLP vaccines targeting NeoAg identified using the HLA-agnostic pipeline augment effector T cell function against these targets. Clinical trial information: NCT02287428. [Table: see text]

A phase 1 study of RTX-321, an engineered red blood cell as an artificial antigen-presenting cell expressing HLA-A*02 with the HPV-16 E7 peptide and 4-1BB ligand with membrane-bound IL-12 for the treatment of HPV 16-positive cancers

TPS2664

Background: High-risk strains of HPV (HPV 16/18) have been associated with the development of multiple cancers, and the associated viral antigens are validated targets from immunotherapy approaches. We engineered red blood cells into allogeneic, off-the-shelf, artificial antigen-presenting cells (aAPCs) that express a human papillomavirus (HPV) 16 E7 peptide bound to human leukocyte antigen (HLA)-A*02:01, the costimulatory molecule 4-1BB ligand (L), and the cytokine interleukin (IL)-12 on the cell surface. This aAPC, RTX-321, activated HPV specific T-cells and promoted effector function in vitro. In animal models using a murine surrogate system, this aAPC approach resulted in robust antigen-specific T-cell expansion, NK cell expansion, tumor control, memory formation and antigen spreading, which led to a broad and robust antitumor immune response . The presence of 4-1BBL and IL-12 induced minimal toxicities in these models due to restriction of the biodistribution of the aAPC to the vasculature and spleen. RTX-321 is a potential in vivo cellular immunotherapy for treating HPV 16-positive cancers including cervical, head and neck and anal cancers. Methods: The RTX-321-01 study is a phase 1 multi-center, dose-escalation study of RTX-321 administered intravenously every 3 weeks in HLA-A*02:01-positive patients with relapsed or refractory HPV 16-positive cancers of the cervix or anal canal, or squamous cell cancers of the head and neck (HNSCC). Patients with cervical cancer or HNSCC will undergo testing for the presence of the HPV 16 virus or provide confirmation from archival tumor tissue prior to enrollment. Patients with anal cancer will not be required to have prospective determination of HPV 16-positive status prior to enrollment given the high incidence in this indication (approximately 80-85 percent of anal cancers). Approximately 18 patients will be enrolled across dose level cohorts to identify the recommended phase 2 dose (RP2D) of RTX-321, followed by RP2D expansion cohorts in specific indications. The starting dose is 1 billion (1x109) cells administered intravenously every 3 weeks (Q3W) and the dose will escalate by half-log increments, following a Bayesian logarithmic regression model (BLRM) with overdose control. Translational studies will investigate the activation and expansion of HPV16 E7 antigen-specific responses as well as broad innate and adaptive responses in multiple peripheral blood samples over the first 3 cycles of therapy as well as in optional paired tumor biopsies. At this time, the study is open and enrolling patients in the first dose escalation cohort (NCT04672980). Clinical trial information: NCT04672980.

Final analysis of a phase 1b, randomized, multicenter study of talimogene laherparepvec (T-VEC) plus pembrolizumab (pembro) combination for the treatment (Tx) of recurrent/metastatic squamous cell carcinoma of the head and neck (R/M HNSCC): MASTERKEY-232

6036

Background: T-VEC, a genetically modified herpes simplex virus-1, is the first FDA- and EMA-approved oncolytic viral immunotherapy designed to enhance systemic antitumor immune responses. R/M HNSCC is a disease with considerable clinical complexity and poor prognosis. Pembro is a PD-1-specific humanized monoclonal antibody currently approved as first-line Tx for this disease, but there is an unmet need among many patients (pts). To meet this gap, the safety and preliminary efficacy of T-VEC plus pembro in pts with R/M HNSCC was evaluated in a phase 1b study (Harrington et al. Clin Cancer Res. 2020). Here, we present results of the final analysis of this study (NCT02626000). Methods: Eligible pts (≥18 yrs) had ECOG-PS of 0 or 1; histologically confirmed R/M HNSCC of the oral cavity, oropharynx, hypopharynx, or larynx unsuitable for curative surgical resection or radiotherapy; platinum-refractory and with injectable tumors. Pts with known active CNS metastases and any systemic or local therapy 28 days before enrollment were excluded. T-VEC was injected intralesionally up to 8.0 mL of 106 PFU/mL according to lesion sizes on day 1; after 3 weeks, subsequent doses of ≤8.0 mL of 108 PFU/mL were given Q3W. Pembro was given intravenously at 200 mg Q3W. Pts were followed-up for 36 mos after the last patient was enrolled in the study. Key endpoints (irRECIST per investigator assessment) were objective response rate (ORR), best overall response (BOR), disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Results: A total of 36 pts (80.6% male) were enrolled and treated: 28 (77.8%) had confirmed PD-L1-positive tumor (CPS ≥1), 5 (13.9%) were HPV-positive, 13 (36.1%) had metastatic disease, and 19 (52.8%) had prior lines of therapy in the R/M setting. At the final analysis, 7 pts (19.4%) completed the study, and 29 (80.6%) discontinued the study due to death. Safety profile was consistent with that at 1-yr analysis (Harrington et al. Clin Cancer Res. 2020). Confirmed ORR was seen in 16.7% (95% CI, 6.4–32.8). No patient had a complete response as their BOR, 6 (16.7%) had a partial response, 8 (22.2%) had stable disease, 6 (16.7%) had progressive disease, 6 (16.7%) were unevaluable, and 10 (27.8%) died before the first response assessment. The DCR was 38.9% (95% CI, 23.1–56.5). The median DOR was 45.9 mos (95% CI, 8.5–NE). The median PFS was 3.0 mos (95% CI, 2.0–5.8), and the median OS was 5.8 mos (95% CI, 2.9–11.4). Conclusions: The safety results at 3 yrs for T-VEC plus pembro in pts with R/M HNSCC were consistent with those of the 1-yr analysis. Although the response rate was consistent with that observed with pembro alone in historical HNSCC studies, the extended DOR in responding patients warrants further investigation. Clinical trial information: NCT02626000.

A phase 1/2 study with open-label, dose escalation phase followed by single-arm expansion at the maximum tolerated dose to assess the safety, tolerability, pharmacokinetics, pharmacodynamics, and efficacy of NT219 injection alone and in combination with cetuximab in adults with advanced solid tumors and head and neck cancer

TPS3156

Background: NT219 is a small molecule, dual inhibitor of insulin receptor substrates (IRS) 1/2 and signal transducer and activator of transcription 3 (STAT3), effecting IRS1/2 degradation and inhibiting STAT3 phosphorylation. IRS1/2 and STAT3 are major signaling junctions regulated by various oncogenes, altered during epithelial to mesenchymal transition (EMT) and drug resistance, and play an important role in the tumor and its microenvironment. Patient derived xenograft (PDX) models have shown that inhibition of both IRS and STAT3 is essential to overcome targeted epidermal growth factor receptor inhibitor (EGFRi) resistance, and NT219 has demonstrated efficacy as monotherapy and in combination with immune oncology therapies. Particularly, both pathways have been found to be relevant in resistance to cetuximab in head and neck squamous cell carcinoma (HNSCC) PDX models. Methods: This phase 1/2 study (Clinical trial: NCT04474470) began in September 2020. The phase 1 component has a dose escalation arm of NT219 as a single agent at doses ranging between 3mg/kg and 50mg/kg in adult subjects with recurrent and/or metastatic solid tumors enrolled in sequential dose cohorts of 3 to 6 subjects, in a conventional 3+3 design aiming to establish the safety of single agent NT219. Following the conclusion of follow up on the third dose cohort, an additional dose-escalation arm of NT219 in combination with standard dose cetuximab will be opened in patients with recurrent and/or metastatic HNSCC and colorectal cancer, aiming to establish the safety of NT219 when combined with cetuximab. In the expansion phase, 29 patients will be enrolled at the recommended phase 2 dose in combination with standard dose cetuximab in patients with recurrent/metastatic HNSCC. The primary objectives of the trial are safety, tolerability, MTD, and RP2D and preliminary efficacy of NT219 alone and in combination with cetuximab. Measurements of STAT3 and IRS1/2 phosphorylation in biopsy specimens and TILs will be evaluated as potential biomarkers. NT219 provides a first-in-class treatment for patients with resistant neoplastic disease. The current trial will provide important data in patients with recurrent/metastatic cancers, particularly, HNSCC on the effects of the inhibition of STAT3 and IRS1/2 pathways as a novel therapeutic approach. Clinical trial information: NCT04474470.

CMP-001-007: Open-label, phase 2 study of intratumoral CMP-001 + pembrolizumab in patients with recurrent or metastatic head and neck squamous cell carcinoma

TPS6089

Background: PD-1 blockade ± chemotherapy has recently become a primary systemic therapy recommended by NCCN guidelines for patients (pts) with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). However, most pts still do not respond to treatment, indicating a large unmet need for pts with unresectable disease. CMP-001 is a toll-like receptor 9 (TLR9) agonist comprising a CpG-A oligodeoxynucleotide packaged in a virus-like particle that can induce type I interferon secretion from tumor-associated plasmacytoid dendritic cells, promoting a Th1-like chemokine milieu in the tumor microenvironment and inducing an antitumor CD8+ T-cell response. In a phase (ph) 1b study in pts with metastatic melanoma, intratumoral (IT) injection of CMP-001 + intravenous (IV) pembrolizumab (pembro) reversed PD-1 blockade resistance, induced responses in injected and noninjected lesions, and had an acceptable safety profile (Milhem et al, SITC 2020). This combination is therefore being tested in pts with HNSCC. Methods: CMP-001-007 (NCT04633278) is an open-label, multicenter, ph 2 study designed to investigate the efficacy and safety of CMP-001 + IV pembro in adult pts with histologically or cytologically confirmed R/M HNSCC considered incurable by local therapies. Eligible pts have undergone a pretreatment tumor biopsy, received no prior systemic therapy in the R/M setting, and have primary tumor locations of oropharynx, oral cavity, hypopharynx, or larynx. In addition, pts must have PD-L1-positive tumors (combined positive score ≥1), known tumor human papillomavirus (HPV) status (for oropharyngeal cancer), and measurable disease per RECIST v1.1 with ≥1 lesion amenable to IT injection. Pts with primary tumors in the nasopharynx are excluded. Enrolled pts will receive CMP-001 10 mg once weekly for 7 doses and every 3 weeks (Q3W) thereafter. The first dose may be administered subcutaneously or via IT injection, with all subsequent doses administered IT. All pts will also receive pembro 200 mg IV Q3W after the CMP-001 injection. Treatment continues until unacceptable toxicity or disease progression. The primary endpoint is investigator-assessed objective response rate (ORR) per RECIST v1.1. Secondary endpoints include safety, duration of response (DOR), progression-free survival (PFS), overall survival, and effects of HPV infection and PD-L1 expression on ORR, DOR, and PFS. Exploratory endpoints include analyses of baseline and changes from baseline in tumor or serum biomarkers related to TLR9, immune checkpoints, and potential predictors of response, as well as serum concentrations of CXCL10 and CMP-001. Refer to clinicaltrials.gov/ct2/show/NCT04633278 for the most current information on enrolling sites. Clinical trial information: NCT04633278.

TrilynX: A phase 3 trial of xevinapant and concurrent chemoradiation for locally advanced head and neck cancer

TPS6091

Background: Concurrent chemoradiotherapy (CRT) is the standard of care for previously untreated patients with locoregionally advanced squamous cell carcinomas of the head and neck (LA-SCCHN). Xevinapant (Debio 1143) is an orally available antagonist of inhibitor of apoptosis proteins with the potential to enhance the antitumor activity of platinum-based chemotherapy and radiotherapy. The radiosensitizing effect of xevinapant is mediated through caspase activation and TNF, IFNγ, CD8 T cell-dependent pathways. Three-year follow-up results from a randomized Phase 2 study showed significant improvements of xevinapant versus placebo in addition to standard chemoradiation (CRT) for locoregional control (LRC) rate at 18 months, PFS and OS. The addition of xevinapant was well tolerated, manageable and did not jeopardize backbone therapy [1, 2]. Methods: TrilynX is a multinational, Phase 3, double-blind, placebo-controlled, randomized clinical study assessing the efficacy of xevinapant in combination with concurrent CRT compared with placebo in combination with CRT for LA-HNSCC. Adult patients with newly diagnosed, pathologically proven, treatment-naive LA-SCCHN will be enrolled. Study population will include hypopharynx, larynx and p16-negative oropharyngeal. Other eligibility criteria: ECOG PS 0 or 1, AST and ALT ≤ 3.0 x ULN, total bilirubin ≤ 1.5 × ULN, and eligible for definitive CRT. Approximately 700 eligible patients will be randomly assigned to receive oral xevinapant at 200 mg per day on days 1 to 14 of 3-week cycles or placebo for three cycles in combination with cisplatin (100 mg/m², q3w) for three cycles, and concomitant standard fractionation intensity-modulated radiotherapy (70 Gy/7 weeks). The concurrent CRT period will be followed by a monotherapy period consisting of further three cycles of xevinapant or placebo. The primary endpoint is Event Free Survival (EFS) assessed by a Blinded Independent Radiological Committee (BIRC). An interim analysis will occur when 279 EFS events as assessed by the BIRC are observed. The primary analysis will occur once 429 EFS events are observed. TrilynX has ̃90% power to detect the expected hazard ratio benefit of 0.73. Secondary end-points include OS, PFS, LRC, ORR, HRQL, and safety. Data driven design, patients will be followed up for a minimum of 60-months. PK sparse sampling is performed to assess exposure-response relationships with efficacy and safety. Biomarkers of response and resistance will be explored. TrilynX started in August 2020 and it is ongoing. References: [1] X. Sun et. al, Lancet Oncol; 21(9): 1173-1187, 2020. [2] J. Bourhis et al., Ann Oncol; 31 (suppl 4): LBA39, 2020. Clinical trial information: NCT04459715.

INDUCE-3: A randomized, double-blind study of GSK3359609 (GSK609), an inducible T-cell co-stimulatory (ICOS) agonist antibody, plus pembrolizumab (PE) versus placebo (PL) plus PE for first-line treatment of PD-L1-positive recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC)

TPS6591

Background: Pembrolizumab as part of first-line treatment for patients (pts) with R/M HNSCC has improved survival. However, in order to further improve outcomes in this population investigation of rational combinations targeting different mechanisms that cancers exploit to evade the immune system is required. ICOS, a member of the CD28/B7 immunoglobulin receptor superfamily, provides a co-stimulatory signal augmenting T-cell proliferation, cytokine production, cytotoxic function and survival. GSK609 is a humanized IgG4 antibody selected for its potent agonist activity and non-depleting properties. The rationale for targeting ICOS with GSK609 plus PD-1 blockade with PE is supported by preclinical and clinical evidence (Rischin, et al. Annals of Oncol 2019;30[Supplement_5]:v454–5). INDUCE-3 trial (NCT04128696) will explore if the addition of GSK609 to PE improves outcomes of pts with R/M HNSCC. Methods: INDUCE-3 uses a 2-in-1 adaptive design that has the option to seamlessly expand from an initial Phase 2 to a Phase 3 study. Pts (n = 600) will be stratified by PD-L1 status and HPV status (oropharynx only) then randomly assigned in a 1:1 ratio to receive GSK609 plus PE or PL plus PE, every 3 weeks until progression, unacceptable toxicity, or up to 35 cycles. GSK609 plus PE will be assessed for superiority versus PL plus PE in overall survival (OS) and progression-free survival (PFS) per RECISTv1.1 as dual primary endpoints; secondary endpoints include PFS per immune-based RECIST; milestone OS; safety and tolerability; time to deterioration in patient-reported physical function and pain. Efficacy and patient-reported outcome endpoints will be assessed in the PD-L1 combined positive score (CPS) ≥1 and ≥20 populations. Key eligibility criteria are aged ≥18 years; locally incurable R/M HNSCC of the oral cavity, oropharynx, hypopharynx, or larynx; no prior systemic therapy in the R/M setting; PD-L1 CPS ≥1 by central testing; measurable disease per RECIST v1.1 and ECOG PS 0/1. Recruitment is ongoing in countries across the globe. Funding: Study is funded by GlaxoSmithKline and in collaboration with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Clinical trial information: NCT04128696 .

Phase III LEAP-010 study: first-line pembrolizumab with or without lenvatinib in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC)

TPS6589

Background: The PD-1 inhibitor pembrolizumab is currently approved as first-line monotherapy for patients with R/M HNSCC whose tumors express PD-L1 combined positive score (CPS) ≥1. In a phase 1b/2 trial (NCT02501096) of pembrolizumab plus lenvatinib (multikinase inhibitor of VEGFR 1-3, FGFR 1-4, PDGFRa, RET, and KIT) in solid tumors, the combination demonstrated promising antitumor activity and a manageable safety profile in patients with HNSCC. LEAP-010 (NCT04199104) is a randomized, double-blind, placebo-controlled, phase 3 study that will evaluate the efficacy and safety of first-line pembrolizumab with or without lenvatinib in patients with PD-L1–positive R/M HNSCC. Methods: Key eligibility criteria include histologically confirmed R/M HNSCC incurable by local therapies, PD-L1–positive tumor (CPS ≥1) as determined by central laboratory, measurable disease as assessed by blinded independent central review (BICR) per RECIST v1.1, and ECOG performance status (PS) 0 or 1. Patients will be randomly assigned 1:1 to pembrolizumab plus lenvatinib or pembrolizumab plus placebo. Randomization will be stratified by PD-L1 status defined by tumor proportion score ( < 50% vs ≥50%), human papillomavirus status for oropharynx cancer (positive vs negative), and ECOG PS (0 or 1). Patients will receive intravenous pembrolizumab 200 mg every 3 weeks for 35 cycles (~2 years) and oral lenvatinib 20 mg or placebo once daily; patients may continue to receive lenvatinib or placebo after pembrolizumab treatment is complete. Treatment will continue until BICR-verified disease progression or unacceptable toxicity. Pembrolizumab retreatment (second course) for 17 additional cycles will be allowed for eligible patients who stop pembrolizumab and subsequently experience BICR-verified disease progression. These patients could have stopped treatment with stable disease, partial response, or complete response or after 35 cycles of pembrolizumab for reasons other than disease progression or toxicity. Tumor imaging assessment will be performed at week 6, then every 6 weeks until 1 year, and thereafter every 9 weeks. Primary end points are objective response rate and progression-free survival, assessed by BICR per RECIST v1.1, and overall survival. Secondary end points are duration of response and safety and tolerability. Recruitment is ongoing; planned enrollment is ~500 patients. Clinical trial information: NCT04199104 .

Abstract B51: Novel syngeneic animal model of tobacco-associated oral cancer reveals the activity of in situ anti-CTLA-4

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Tobacco use is the main risk factor for HNSCC, and tobacco-associated HNSCCs have poor prognosis and response to available treatments. Recently approved anti-PD-1 immune checkpoint inhibitors showed limited activity (≤20%) in HNSCC, highlighting the need to identify new therapeutic options. For this, mouse models that accurately reflect the complexity of the HNSCC mutational landscape and tumor immune environment are urgently needed. Here, we report the first mouse HNSCC model system that recapitulates the human tobacco-related HNSCC mutanome, in which tumors grow when implanted in the tongue of immunocompetent mice. These HNSCC lesions have similar immune infiltration and response rates to anti-PD-1 (≤20%) immunotherapy as human HNSCCs. Remarkably, we found that &gt;70% of HNSCC lesions respond to intratumoral anti-CTLA-4. This syngeneic HNSCC mouse model provides a platform for the development of novel immunotherapeutic options for HNSCC.

Note:This abstract was not presented at the conference.

Citation Format: Zhiyong Wang, Victoria H. Wu, Michael M. Allevato, Mara Gilardi, Robert Saddawi-Konefka, Yudou He, Juan Luis Callejas-Valera, Lynn Vitale-Cross, Daniel Martin, Panomwat Amornphimoltham, James Mcdermott, Yusuke Goto, Alfredo A. Molinolo, Andrew B. Sharabi, Ezra E.W. Cohen, Qianming Chen, Guy Lyons, Ludmil B. Alexandrov, J. Silvio Gutkind. Novel syngeneic animal model of tobacco-associated oral cancer reveals the activity of in situ anti-CTLA-4 [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B51.

Preclinical evaluation of anti-ROR1 CAR T cells employing a ROR1 binding SCFV derived from the clinical stage mab cirmtuzumab

41

Background: Chimeric antigen receptor (CAR)-modified T cells (CAR-T) were generated targeting cells expressing ROR1, which is present on many malignant cancers and has been associated with cancer stemness and chemo-resistance. The ROR1 CAR utilizes the humanized single-chain fragment variable (scFv) binding domain of UC-961 (cirmtuzumab), which exhibits high affinity and specificity for human ROR1 and has demonstrated an excellent safety profile in Phase 1 studies. Methods: CAR constructs with varying spacer regions and intracellular co-stimulatory domains, using the scFV of cirmtuzumab, were constructed and used to generate CAR-T cells from healthy donors. These ROR1 CAR-T cells were tested for cytotoxicity against lymphoid cancer cells in vitro and in vivo studies that employed immune-deficient mice engrafted with labeled human leukemia cells MEC1 or MEC1-ROR1, which had been transfected to stably express ROR1. Results: The 2nd generation and 3rd generation CAR-T-cells with analogous spacer regions were comparably potent and selectively cytotoxic for cells bearing the ROR1 target antigen. But the 2nd generation CARs demonstrated greater potency in vitro even at low effector to target ratios. For the in vivo studies, mice received a single injection of ROR1 CAR-T cells or activated T cells from the same donor as a control. The ROR1 CAR-T cells rapidly cleared the leukemic cells from the animals, whereas animals receiving control T cells or no therapy quickly succumbed to progressive disease within 3 weeks. The administered CAR-T products remained highly active following administration and could be detected for ≥ 3 months without evidence for T cell exhaustion. Conclusions: The generated CAR-T cells utilizing constructs with the Fv of cirmtuzumab, a humanized mAb highly specific for ROR1, onco-embryonic surface antigen, effectively and selectively killed neoplastic cells bearing ROR1 both in vitro and in vivo. As ROR1 expression and signaling has been associated with cancer stemness and chemo-resistance utilizing ROR1 CAR-T therapy to target cancer cells might mitigate tumor escape. These data strongly support the rationale for continued development of our ROR1 CAR-T.

An open label, nonrandomized, multi-arm, phase II trial evaluating pembrolizumab combined with cetuximab in patients with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC): Results of cohort 1 interim analysis

6033

Background: Pembrolizumab (a humanized monoclonal antibody blocking programmed death receptor-1[PD-1]), and cetuximab (a chimeric monoclonal antibody inhibiting epidermal growth factor receptor) are both FDA-approved, second-line monotherapies for R/M HNSCC. This is the first trial to evaluate anti-tumor efficacy of dual therapy with pembrolizumab and cetuximab. Previously reported safety data demonstrated favorable toxicity. An interim futility analysis of cohort 1 (anti-PD-1/PD-L1 and cetuximab naïve) was completed per protocol. Methods: Patients (pts) with platinum-refractory/ineligible, R/M HNSCC were treated with pembrolizumab 200mg IV on day 1 and cetuximab 400mg/m2 loading dose followed by 250mg/m2 weekly (21-day cycle). Primary endpoint: overall response rate (complete and partial responses) by 6 months (mo). Secondary endpoints: 12-mo progression-free survival (PFS) probability, overall survival, response duration, safety, correlative analyses. Results: 14 evaluable pts were enrolled March 2017-October 2018. Median age 60y (range 47-86y), M:F 6:8, ECOG (0:1) 2:12, 14 mucosal primaries (9 oral cavity, 2 HPV-mediated oropharynx, 2 non-EBV-associated nasopharynx, 1 larynx). 11 pts (79%) had no prior lines of systemic therapy for R/M HNSCC (range 0-1). 6 pts (42.8%) had a partial response by 6 months, meeting pre-planned criteria for trial continuation. 4 pts (28.6%) had stable disease and 4 (28.6%) had progressive disease. Median PFS was 128 days (4.3 mo). Median duration of response was 160.5 days (5.4 mo) for partial responders and 133 days (4.4 mo) for pts with stable disease. Disease control rate (partial + stable) was 71.4%. There were 7 grade 3 treatment-related toxicities. 2 pts discontinued cetuximab due to toxicity, however, both continued pembrolizumab. Conclusions: Interim analysis indicates that pembrolizumab plus cetuximab is potentially active for platinum-refractory/ineligible pts with R/M HNSCC. These results meet protocol specifications for trial continuation. Final results will include PD-L1 expression data. Clinical trial information: NCT03082534.

Afatinib versus methotrexate as second-line treatment for patients with recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) progressing on or after platinum-based therapy: LUX-Head & Neck 3 phase III trial

6024

Background: In a previous global phase III trial (LUX-Head & Neck 1), second-line (2L) afatinib significantly improved PFS vs methotrexate (MTX) in pts with R/M HNSCC. Here, we compared efficacy/safety of 2L afatinib vs MTX in Asian pts with R/M HNSCC. Methods: Pts progressing on/after platinum therapy were randomized (2:1) to 40 mg/day afatinib (feeding tube or oral) or 40 mg/m2/week iv MTX. Primary endpoint was PFS by independent review. Secondary endpoints were OS, ORR, and patient-reported outcomes. Results: 340 pts were randomized (afatinib 228, MTX 112). Median (range) duration of treatment (Tx) was 3.0 ( < 0.1–35.9) and 1.4 ( < 0.1–8.8) mos, respectively. Afatinib significantly decreased the risk of progression or death by 37% compared with MTX (HR 0.63; 95% CI: 0.48, 0.82 p = 0.0005, median PFS, 2.9 vs 2.6 mos; landmark analysis at 12 and 24 wks, 58 vs 41%, 21 vs 9%). There was no significant difference in OS (HR 0.88; 95% CI: 0.68, 1.13; median 6.9 vs 6.4 mos). ORR was 28% with afatinib and 13% with MTX (OR 2.8; 95% CI: 1.5, 5.2, p = 0.016). More pts had clinically relevant improvements in global health status/quality of life (GHS/QoL; 40 vs 23%, p < 0.01), swallowing (34 vs 18%, p = 0.01) and pain (34 vs 25%, p = 0.22) with afatinib vs MTX. Post-baseline change in GHS/QoL score was more favorable with afatinib (p < 0.001). Treatment-related adverse events (TRAEs; all/grade ≥3) were reported in 89/16% and 67/23% pts with afatinib and MTX. The most common grade ≥3 TRAEs were rash/acne (4%), diarrhea (4%), and stomatitis (3%) with afatinib, and anemia, leukopenia, and fatigue (all 5%) with MTX. Fatal AEs were reported in 23 and 11% pts with afatinib and MTX. Two ( hypoglycemia, pneumonitis/lung infiltration) and 4 pts had fatal AEs considered related to Tx with afatinib and MTX. 11% and 17% pts discontinued Tx due to TRAEs. Conclusions: LUX-Head & Neck 3 achieved its primary endpoint. Two randomized phase III trials have now demonstrated clinical benefit with 2L afatinib vs MTX. Safety data were consistent with the known tolerability profiles of afatinib and MTX. Clinical trial information: NCT01856478.

Pembrolizumab (pembro) for recurrent head and neck squamous cell carcinoma (HNSCC): Post hoc analyses of phase 3 KEYNOTE-040 prior radiation treatment (RT) and disease state

6026

Background: The open-label, randomized, phase 3 KEYNOTE-040 study (NCT02252042) showed that pembro vs standard of care (SOC) chemotherapy prolonged survival in patients (pts) with recurrent and/or metastatic HNSCC whose disease progressed during/after platinum-based therapy. Post hoc analyses were conducted to evaluate pembro vs SOC by prior RT and disease state (metastatic, locoregionally recurrent [referred to as recurrent herein], or recurrent and metastatic [R/M]). Methods: Pts (N = 495) were randomly assigned (1:1) to receive pembro (200 mg Q3W) or investigator choice of methotrexate (40 mg/m2 QW), docetaxel (75 mg/m2 Q3W), or cetuximab (400 mg/m2 loading dose, then 250 mg/m2 QW). Primary end point was OS; PFS and ORR were secondary end points. Results: 175, 97, and 195 pts had metastatic, recurrent, and R/M disease, respectively (28 pts had unknown disease state); 64 pts had no prior RT; 431 pts had prior RT. As in the ITT population, prolonged survival benefit and trend toward improved PFS and ORR was observed with pembro vs SOC in pts with prior RT (Table), and prolonged survival benefit was observed with pembro vs SOC in pts with metastatic and R/M, but not recurrent, disease. Conclusions: In this post hoc analysis, patients with prior RT benefited from treatment with pembro vs SOC. For patients without RT, sample sizes are too small to draw any definitive conclusions. Survival benefit of pembro vs SOC was observed in pts with metastatic and R/M disease. Clinical trial information: NCT02252042. [Table: see text]

KEYNOTE-689: Phase 3 study of adjuvant and neoadjuvant pembrolizumab combined with standard of care (SOC) in patients with resectable, locally advanced head and neck squamous cell carcinoma

TPS6090

Background: Evidence of efficacy and pathological response at the time of surgery was reported in two phase 2 studies (NCT02296684 and NCT02641093) of preoperative pembrolizumab in patients with high-risk, resectable, locally advanced (LA) head and neck squamous cell carcinoma (HNSCC). The randomized, open-label, phase 3 KEYNOTE-689 trial ( NCT03765918) will evaluate efficacy and safety of pembrolizumab as neoadjuvant and adjuvant therapy in combination with SOC (radiotherapy ± cisplatin) in patients with previously untreated, resectable LA HNSCC. Methods: Patients with newly diagnosed LA HNSCC will be randomly assigned 1:1 to two treatment arms. Patients in arm A will receive neoadjuvant pembrolizumab (200 mg Q3W for two cycles) followed by surgical resection then SOC plus adjuvant pembrolizumab (15 cycles). Patients in arm B will undergo only surgical resection followed by adjuvant SOC. Eligibility criteria will include age ≥18 years; newly diagnosed, resectable, stage III/IVA HNSCC (AJCC Cancer Staging Manual, 8th edition); and ECOG performance status 0-1. Randomization will be stratified by primary tumor site (oropharynx/oral cavity vs larynx vs hypopharynx), tumor stage (III vs IVA), and HPV p16 status (oropharynx p16 positive vs oropharynx p16 negative or larynx/hypopharynx/oral cavity). Treatment will continue until disease progression, unacceptable toxicity, or decision to withdraw. Patients in arm A will undergo the first radiologic imaging assessment after two cycles of neoadjuvant pembrolizumab and before surgery. In both arms, postoperative imaging will be performed 12 weeks after SOC, then every 3 months until the end of year 3, and then every 6 months until the end of year 5. Dual primary end points are major pathological response, defined as ≤10% invasive squamous cell carcinoma within resected primary tumor and sampled regional lymph nodes per blinded central pathology, and event-free survival. Secondary end points include overall survival, pathological complete response, and safety and tolerability. Recruitment is ongoing and will continue until ~600 patients are enrolled. Clinical trial information: NCT03765918.

Phase 1b/2, open label, multicenter study of intratumoral SD-101 in combination with pembrolizumab in anti-PD-1 treatment naïve patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC)

6039

Background: SD-101, a synthetic CpG-ODN agonist of TLR9, stimulates dendritic cells to release IFN-alpha and mature into antigen presenting cells - activating T cell anti-tumor responses. Pembrolizumab has demonstrated activity in HNSCC. Study DV3-MEL-01 (NCT02521870) assesses safety and efficacy of SD-101 in combination with pembrolizumab in patients with recurrent/metastatic HNSCC. We have previously reported a 27.3% ORR in 22 patients receiving 8 mg SD-101/injection in the modified ITT after at least 2 CT scans due to late responses (Abstract 3560, ESMO 2018). Higher efficacy at a lower SD-101 dose, 2 mg/injection, has been reported in advanced melanoma patients (LBA 45, ESMO 2018). Consequently, this dose is now being assessed in HNSCC. We report preliminary data with the 2 mg/injection dose in 23 patients in mITT at the first CT scan. Methods: Anti-PD-1/PD-L1 naïve patients received 2 mg SD-101 intratumorally in 1 - 4 lesions (weekly x 4 doses then Q3W x 7 doses). Pembrolizumab is was administered IV at 200 mg Q3W. Responses were assessed per RECIST v1.1. Results: 28 patients enrolled: median age 63 y/o, male 68%; ECOG PS 0-1 (18%/82%); mean prior lines of systemic therapy 1 (0-3); mean treatment duration 70 days (1-253). Primary tumors: 19 (68%) oropharyngeal; 3 (10%) laryngeal; 2 (7%) hypopharyngeal; 4 (14%) unknown. Mean number of target lesions: 1.82 (1 to 5). HPV status: 7 (25%) +, 9 (32%) -, 12 (43%) unknown. 18 (64 %) discontinued treatment: 12 (42%) due to PD, 4 (16%) deaths, 1 (3%) consent withdrawn, 1 (3%) went to hospice. Mean follow up 2.70 months. Safety: 16 non-treatment-related SAEs in 9 patients. 2 treatment-related Grade ≥3 AEs: sepsis (4%) and lymphopenia (4% ). No treatment-related deaths. Efficacy: 23 patients in the mITT population with first CT scan at day 64: ORR: CR: 2, PR: 3 (22%); SD: 6 (26%), PD: 7 (30%), non-evaluable: 5 (22%). Disease control rate (48%). 5 patients on study have not had a CT scan. Conclusions: SD-101 with Pembrolizumab shows early promising data and is well tolerated. Additional follow-up scans from both dose cohorts are being evaluated and will be presented. Clinical trial information: NCT02521870.

KEYNOTE-630: Phase 3 study of adjuvant pembrolizumab versus placebo in patients with high-risk, locally advanced cutaneous squamous cell carcinoma

TPS9597

Background: Among patients with high-risk, locally advanced (LA) cutaneous squamous cell carcinoma (cSCC) who receive current standard-of-care surgical resection and adjuvant radiotherapy, ~40-50% develop local recurrence and regional metastasis ( J Clin Oncol. 2018;36:1275-1283). Recent data suggest that programmed death 1 inhibitors such as pembrolizumab may provide a well-tolerated, effective, and durable response in patients with LA or metastatic cSCC. To evaluate the efficacy and safety of adjuvant pembrolizumab in patients with high-risk LA cSCC, the randomized, double-blind, placebo-controlled phase 3 KEYNOTE-630 trial (NCT03833167) will be conducted. Methods: After surgical resection and radiotherapy for high-risk LA cSCC, eligible patients will be randomly assigned 1:1 to intravenous pembrolizumab (400 mg Q6W) or placebo for up to 9 cycles (~1 year), with radiographic imaging at least every 12 weeks until year 2 and then every 6 months until the end of year 5 to assess treatment response. Eligibility criteria will include age ≥18 years, histologically confirmed LA cSCC with ≥1 high-risk feature at the primary site of malignancy, macroscopic resection with or without microscopic positive margins, completed adjuvant radiotherapy, disease free ≤28 days from randomization, and ECOG performance status 0-1. Treatment will be discontinued at disease recurrence, start of new anticancer treatment, unacceptable toxicity, intercurrent illness that prevents treatment, pregnancy, investigator or patient decision to withdraw, or administrative reasons that require treatment cessation. After the first disease recurrence, all patients who meet crossover or retreatment criteria may receive pembrolizumab 400 mg Q6W for up to 18 cycles. Adverse events will be monitored throughout the study and graded according to the NCI CTCAE, version 4.0. The primary efficacy end point will be investigator-assessed and biopsy-confirmed recurrence-free survival. Secondary end points will be overall survival, health-related quality of life, and safety. Recruitment is ongoing in 19 countries and will continue until approximately 570 patients are enrolled. Clinical trial information: NCT03833167.

Abstract PR12: Functional identification and therapeutic targeting of tumor neoantigens

Accurate identification of tumor-specific neoantigens (NeoAg) is essential for the development of effective personalized cancer vaccines and cellular immunotherapies. The success rates for purely computational approaches which rely on predicted HLA-binding have been disappointing, as these generally ignore 85-90% of total mutations and find less than 5% of those selected can be confirmed as T-cell targets. We have developed a novel NeoAg identification platform in which WES and RNAseq metadata is used to nominate mutations for subsequent functional T-cell analysis using autologous PBMC and/or TIL. Applying this platform to tumors of low mutational burden including PDAC, HNSCC, and MSS-CRC, we report that an average of 35% of expressed mutations selected for functional testing can be verified as neoantigens, and that a significant number of these would be missed by HLA-binding algorithms. Responses comprise both type I and type 2 CD4+ and CD8+ effector T-cells recognizing both “passenger” mutations and known activating mutations in driver oncogenes such as KRAS, PIK3CA, and NRAS. Additionally, we have established a single-cell platform for isolation of T-cell receptors (TCR) against these shared recurrent mutations, and have opened a phase 1b clinical trial to evaluate the efficacy of personalized NeoAg vaccination in solid tumors.

Citation Format: Stephen Phillip Schoenberger, Aaron M. Miller, Luise A. Sternberg, Leslie Montero Cuencac, Milad Bahmanof, Zeynep Koasaloglu-Yalcin, Manasa Lanka, Ashmitaa Premlal, Pandurangan Vijayanand, Jason Greenbaum, Allesandro Seatte, Ezra E.W. Cohen, Bjoern Peters. Functional identification and therapeutic targeting of tumor neoantigens [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr PR12.

Safety and efficacy of checkpoint inhibition (CI) in cancer patients (pts) with concurrent human immunodeficiency virus (HIV) infection

136

Background: There is limited knowledge about the use of CI in cancer pts with HIV. Here we report the safety and efficacy of these agents in this pt population. Methods: We identified cancer pts with HIV at UCSD who received ≥1 dose of ipilimumab, pembrolizumab or nivolumab (anti-PD1), or the combination of ipi+nivo and had ≥1 follow-up visit. Data regarding clinical history, treatment response, and toxicity were collected. Results: Three pts had head and neck squamous cell carcinoma (HNSCC), 2 pts had advanced melanoma, 1 pt had cutaneous SCC, and 1 pt had SCC of unknown primary (suspected lung). Age ranged from 51-73 years. All pts had ECOG PS 0-1 at time of treatment. Six pts received anti-PD1 for a median of 8 cycles (range 2-35); one pt received 4 cycles of ipi+nivo q3wk followed by 4 cycles of anti-PD1. All 7 pts were on anti-retroviral therapy (ART) and had well-controlled HIV (viral load < 400 copies/mL) with varying degrees of immune dysfunction: 4 pts with moderate immune dysfunction (100-199), 1 pt with mild immune dysfunction (200-350), and 2 pts with normal immune function ( > 350). 3/7 pts (43%) had ≥1 clinically significant irAE of grade ≤2 (fatigue and rash); one pt who received ipi+nivo developed grade 3 hepatitis and required systemic steroids though progressive disease likely contributed. No atypical toxicities were seen. Objective responses were seen in 4/7 pts (57%) with 1 complete response and 3 partial responses; two pts had progressive disease and response was not yet evaluable in 1 pt. Four patients died from clinical deterioration unrelated to CI or immunodeficiency. Conclusions: CI demonstrated significant anti-tumor activity in cancer pts with well-controlled HIV. The toxicity profile is consistent with known irAEs. Further study of these agents in this pt population is warranted.

Tumor profiling from whole-genome and whole transcriptome sequencing to uncover gene fusions and structural variations in clinically relevant cancer genes

e23118

Background: Current targeted cancer therapies rely on the identification of clinically relevant somatic alterations in the tumor. Hotspot gene-panels and exome sequencing are designed to quickly assess somatic variations in frequently mutated regions and/or the coding regions of relevant genes, but they have limited ability to detect complex genomic rearrangements or novel structural variations. Here, we describe an integrative and comprehensive approach to fully characterize the genomic complexity of solid tumors using high throughput whole genome sequencing (WGS) and whole transcriptome sequencing (RNA Seq). Methods: We performed WGS and high-depth sequencing of known cancer genes in 14 paired tumor-normal samples of a variety of tumor types. Tumor-specific somatic alteration assessments included protein-coding mutations, copy number variations, gene fusions and structural variants. In addition, RNA Seq data was analyzed to identify expressed somatic alterations. Results: We identified 2 novel fusion genes as well as important structural alterations which could have clinical and therapeutic implications. We described a novel BRAF fusion gene in a cholangiocarcinoma devoid of other known driver mutations. BRAF fusions have not been described previously in cholangiocarcinoma; this fusion may represent an alternative mechanism for MAPK activation and could be a useful drug target. We also identified a novel NTRK3 fusion partner in a glioblastoma tumor. This fusion may imply a novel mechanism for NTRK3 activation. Finally, we identified numerous tandem duplications in an ovarian cancer. Recent advances describe tandem duplication hotspots in ovarian cancer as a potential driver mechanism characterizing a specific mutational signature. Conclusions: Comprehensive genomics assessment of paired tumor-normal samples through whole-genome and transcriptome sequencing can yield additional clinically actionable genomic characteristics that may not be detected in whole-exome or hotspot gene-panel sequencing. These findings have the potential to aid in clinical decision making.

Next generation sequencing of cell free circulating tumor DNA in blood samples of recurrent and metastatic head and neck cancer patients

e17516

Background: Head and Neck Squamous Cell Carcinoma (HNSCC) is an increasingly prevalent disease but effective targeted therapy is lacking. The use of next generation sequencing (NGS) in the identification of novel targets has been suggested as a way to potentially expand therapeutic options and thereby improve outcomes. Methods: Data was collected on patients with recurrent and metastatic (R/M) head and neck cancers who underwent molecular profiling of blood samples utilizing Guardant360, a 70-gene circulating tumor DNA (ctDNA) NGS platform. CtDNA sequencing data was compared to tumor NGS data, when available. Best response to therapy was assessed using RECIST measures. Results: 60 HNSCC patients were evaluated from February 2015 to June 2016. The most common tumor type and histology was oropharyngeal squamous cell carcinoma (n = 21), which was commonly human papillomavirus (HPV) positive (n = 15). Other cancer types included salivary gland and thyroid cancers. The most common mutations identified by ctDNA analysis were TP53 (98%), PIK3CA (43%), NOTCH1 (38%), and ARID1A (36%). These findings were consistent with results from tumor sequencing data (n = 29) where TP53 (48%) and PIK3CA(24%) were also reported with the highest frequency. Importantly, 73% (n = 22) of patients had alterations identified in ctDNA that were not present in tumor specimens. Actionable mutations were identified in 66% of HNSCC and in 50% salivary gland cancer patients. Of patients with actionable mutations, 10% (n = 6) received matched targeted therapy (MTT): 3 (50%) had stable disease (SD), 1 had progressive disease (PD), and 2 were not evaluated. Of those who did not receive targeted therapy (n = 23), 1 (4.3%) patient had a complete response treated with immunotherapy, 11 (47%) had SD, and 11 (47%) had PD. Conclusions: Analysis of ctDNA may play a role in management decisions in R/M HNSCC. The majority of patients had unique mutations identified on ctDNA. The utility of ctDNA NGS and its role in patient management should be explored in future studies.

LUX-head and neck 2: Randomized, double-blind, placebo-controlled, phase III trial of afatinib as adjuvant therapy after chemoradiation (CRT) in primary unresected, high/intermediate-risk, squamous cell cancer of the head and neck (HNSCC) patients (pts)

6001

Background: Locally advanced HNSCC is treated curatively, but recurrence is common. In HNSCC, EGFR is richly expressed and EGFR inhibition is validated treatment (tx); the ErbB family blocker afatinib (A) showed efficacy in recurrent/metastatic disease. This Phase III trial assessed if A after definitive CRT improves disease-free survival (DFS). Methods: Eligible pts had complete response after CRT ≥66 Gy (or equivalent) with concurrent cisplatin or carboplatin but not prior EGFR inhibition, for HNSCC of oral cavity, hypopharynx, larynx, or oropharynx with >10 pack years (pk yrs) tobacco use. Pts were stratified by ECOG PS (0/1) and nodal stage (N0–2a/N2b–3), and randomized 2:1 to A 40 mg/d or placebo (P); tx continued for 18 m if tolerated, or until disease recurrence. The primary endpoint was DFS. Results: Of 669 pts planned, 617 were randomized; A 411, P 206. Median age was 58 yrs; 86% were male; 65% ECOG PS 0; most had smoked (A/P ex-smoker: 66/72%; current: 28/22%). Subsites (A/P) were: oropharynx 53/54%; hypopharynx 21/23%; larynx 18/12%; oral cavity 9/10%. The majority had T3 or 4 (A/P 70/68%) and N2 disease (67/63%). Accrual was halted for futility on independent DMC recommendation: at a pre-planned interim analysis (40% of DFS events), median DFS was A 43.4 m vs P not reached (NR; HR 1.13 [95% CI 0.81–1.57], p=0.48); the Table shows key subgroups. Median treatment duration was A 300.0 d, P 455.5 d. Recurrence was A 23%, P 23%. Dose reduction of A was required in 53% (mostly due to diarrhea, stomatitis). Tx was discontinued due to AEs in A 15%, P 4%. Conclusions: A after CRT did not improve DFS vs P. Subgroup analyses were underpowered to provide definitive conclusions. Harrington and Cohen contributed equally. Clinical trial information: NCT01345669. [Table: see text]

JAVELIN head and neck 100: A phase 3 trial of avelumab in combination with chemoradiotherapy (CRT) vs CRT for 1st-line treatment of locally advanced squamous cell carcinoma of the head and neck (LA SCCHN)

TPS6093

Background: Cisplatin + radiotherapy is a standard-of-care treatment for patients (pts) with LA SCCHN. Combining avelumab (fully human IgG1 anti–PD-L1 antibody) and CRT may synergistically activate multiple immune-mediated mechanisms to effect a robust and durable antitumor response and improve long-term disease control. Methods: JAVELIN Head and Neck 100 (NCT02952586) is a global, multicenter, randomized, double-blind, phase 3 trial of avelumab + cisplatin-based CRT vs placebo + CRT as 1st-line treatment for pts with LA SCCHN. The primary objective is to demonstrate superiority of avelumab + CRT in prolonging progression-free survival (PFS) vs CRT alone. Eligible pts have LA SCCHN of the oral cavity, oropharynx, larynx, or hypopharynx; HPV− or non-oropharyngeal HPV+ disease of stage III, IVa, or IVb; or HPV+ oropharyngeal disease T4, N2c, or N3. Pts must be candidates for cisplatin-based CRT. Other eligibility criteria include ECOG PS ≤1 and no prior systemic treatment for advanced disease. Approximately 640 pts will be randomized 1:1 to receive avelumab 10 mg/kg (1-hour IV) + CRT (intensity-modulated RT [70 Gy/35 fractions] + cisplatin 100 mg/m2 [x3]) or placebo + CRT. There will be 3 treatment phases: lead-in (single dose of avelumab or placebo), CRT (concurrent avelumab or placebo + CRT for 7 weeks), and maintenance (avelumab or placebo Q2W for 12 months). The rationale for this design is to induce an immune response during lead-in and CRT phases, followed by maintenance treatment to prolong and support immune memory development. The primary endpoint is PFS per modified RECIST v1.1. Secondary efficacy endpoints include overall survival, objective response, locoregional failure, distant metastatic failure, and duration of response. Other endpoints include safety, pharmacokinetics, immunogenicity, pt-reported outcomes, and biomarker assessments. Treatment will continue for 12 months following initiation of the maintenance phase or until progressive disease, unacceptable toxicity, or any other protocol-defined criterion for withdrawal occurs. Enrollment in this phase 3 trial began in November 2016. Clinical trial information: NCT02952586.

Comprehensive analysis of tumor NGS data to demonstrate pathways pointing to therapeutic targeting options

e23153

Background: Recent advancements in NGS technology have enabled precision medicine based on tumor-specific genomic alterations. However, the complex nature of tumor biology demands an integrative analysis of genomic variations to identify converging downstream targets potentially regulated by multiple pathways. Methods: Genomic alterations from whole-genome sequencing results were interpreted in the context of pathways. Beyond listing the implicated known pathways based on genomic alterations, we explored protein interactions cross-linking the pathways to converging downstream targets. An in-house analytical pipeline was used to prioritize candidate pathways from MetaBase™, which contains manually curated pathways and interactions based on published experimental results. Custom pathway diagram was then designed manually to depict the most actionable pathways. The manual review consists of context-checking and addressing the concordant/discordant nature of all interactions. Factor such as mutational impact, directionality, mechanism of interaction and known targeted action are taken into account. Results: Comprehensive analysis of the genomic variations in three tumors types revealed activation of multiple oncogenic signaling pathways. Key events driving the tumor in a melanoma sample were NF1/RAS/MEK/ERK, WNT/beta-catenin pathway, and MITF signaling. Three interconnected signaling pathways, WNT, PI3K/AKT, and P53 were impacted by genomic alterations in a colorectal sample, which point to activation of converging downstream targets- CDK6, VEGFA, and COX-2. Integrated discovery of genomic alterations in an esophageal adenocarcinoma sample suggested potential activation of PI3K/AKT/MTOR and p16/Cyclin D1/CDK pathways. This could synergistically activate downstream converging targets- VEGFA, Cyclin D1, CDK6, CDK4, AURKA; some of which also showed relative RNA overexpression, supporting our pathway findings. Conclusions: Comprehensively analyzing the genomic alterations in context of cell signaling pathways provides us insights on how the pathways synergistically affect downstream targetable events, which in turn can impact therapeutic decisions.

Safety of pembrolizumab with chemoradiation (CRT) in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN)

6011

Background: Pembrolizumab (pembro) is a humanized monoclonal antibody that blocks the programmed death receptor-1 (PD-1) interaction with its ligands (PD-L1, PD-L2). While pembro is approved for platinum-refractory, recurrent/metastatic SCCHN, its role in definitive therapy for LA-SCCHN is not yet defined. Here we present the safety results of pembro with cisplatin-based CRT for patients (pts) with LA-SCCHN (NCT02586207). Methods: 27 pts with oropharyngeal (OP), hypopharyngeal (HP), and laryngeal (L) stage III-IVB SCCHN (any HPV status) eligible for cisplatin-based, definitive CRT were enrolled from November 2015 to August 2016 as part of a safety cohort. Pembro was given at a fixed dose of 200 mg IV 4-7 days prior to initiation of CRT and then every 3 weeks during CRT (2 concomitant doses) and then following CRT for 5 additional doses. CRT consisted of weekly cisplatin 40 mg/m2 IV x 6 doses (240 mg/m2 maximum) given concurrently with radiation at a dose of 2 Gy once daily for 35 fractions (total 70 Gy). Safety was determined by the occurrence of CRT or pembro dose-limiting adverse events (AEs) and immune-related AEs (irAEs). Efficacy was defined as complete response (CR) rate on imaging or with salvage surgery at 100 days post-CRT completion. Results: 20 (74%) pts with OP HPV+ and 7 (26%) pts with HPV- (4 L, 2 OP, 1 HP) tumors were enrolled. 21 (78%) completed all planned doses of pembro. 3 discontinued due to irAEs (G2 peripheral motor neuropathy, G3 AST elevation, G1 Lhermitte-like syndrome). 3 discontinued due to protocol reasons (early neck dissection -2 pts, prolonged hospitalization-1 pt). All pts completed the full radiation dose (70 Gy) without significant delay (defined as > 5 days). 23 (85%) received the goal target dose of cisplatin (≥200 mg/m2). There was one pt death due to concurrent illness, unrelated to treatment. The study has been reopened with expansion cohorts of 34 HPV+ pts and 23 HPV- pts to evaluate efficacy. Conclusions: Pembro in combination with weekly cisplatin-based CRT is safe and does not significantly impair radiation or chemotherapy dosing. Efficacy of this combination is being explored further in this study and through larger phase III clinical trials. Clinical trial information: NCT02586207.

A pharmacodynamic study of sirolimus and metformin in patients with advanced solid tumors

TPS11628

Background: Sirolimus is an inhibitor of the mammalian target of rapamycin (mTOR). Metformin has shown anti-cancer activity through its cellular (e.g., AMPK activation) and systemic effects (e.g., inhibition of IGF-1). We conducted a pilot study to test the hypothesis that metformin may potentiate mTOR inhibition by sirolimus. Methods: An open-label, randomized study was conducted in which eligible patients with advanced solid tumors were started on sirolimus (3mg daily) alone for the first 7 days. On day 8, patients were randomized to either receive metformin XL (500 mg daily) plus sirolimus (Arm A) or sirolimus alone (Arm B) for until day 21. From day 22 onwards, all patients recieved metformin XL plus sirolimus. The pharmacodynamic (PD) biomarkers were collected at baseline, day 8 and day 22 of cycle 1. The primary endpoint was to compare the change in PD biomarker phospho-p70S6K, using a two-sample t test (log ratio D22/D8 in arm A vs. arm B). The phospho-p70S6K was measured in peripheral blood T cells using Western blot. The secondary endpoints were to assess objective response rate (RECIST 1.1), toxicity (CTCAE V4.0) and changes in the serum levels of PD biomarkers: fasting glucose, triglycerides, insulin, C-peptide, IGF-1, IGF-1R, IGF-BP, leptin and adiponectin using two-sample t tests. Results: 24 patients were enrolled, at which time an interim futility analysis was conducted. 18 patients were evaluable for the primary endpoint (8 in arm A; 10 in arm B). The mean log ratios D22/D8 in phospho-p70S6K in arms A and B were -0.12 (SD = 0.13) and -0.16 (SD = 0.29), respectively (P = 0.64). Of the 17 pts evaluable for response, the best response was stable disease in 9 patients and progressive disease in 8 patients. There were no dose-limiting or unexpected toxicities. Of the 21 patients evaluable for serum PD biomarkers, there were no significant differences between arms A and B in fasting glucose, triglycerides, insulin, C-peptide, IGF-1, IGF-BP1, IGF-BP3, leptin and adiponectin (P > 0.05 for all). Conclusions: The addition of metformin to sirolimus, although well-tolerated, was not associated with significant changes in phospho-p70S6k and other PD biomarkers. Based on the results of the interim analysis, the trial was terminated. Clinical trial information: NCT02145559.

An open-label, single-arm, multi-institutional phase II trial of avelumab for recurrent, metastatic nasopharyngeal carcinoma

TPS6092

Background: The majority of patients with nasopharyngeal carcinoma (NPC) present with locally advanced disease, with a predilection for early systemic dissemination. For patients who develop recurrent and/or metastatic (R/M) NPC, survival is poor. Following first-line platinum-based regimens, there is no well-defined paradigm for subsequent therapies. Inhibition of PD-L1 with Avelumab is an attractive strategy because Epstein-Barr virus (EBV), the primary causative agent in NPC pathogenesis, universally upregulates PD-L1 expression; proposed mechanisms of upregulation include immune resistance via innate (EBV-induced latent membrane protein-1) and adaptive (Interferon-gamma) mechanisms; increased PD-L1 expression is an independent poor prognostic factor for disease-free survival. Methods: Patients with histologically/cytologically confirmed, EBV-related NPC not amenable to curative intent therapy who received ≥1 prior line of systemic therapy for R/M disease are eligible. Patients must be at least 18 years old, ECOG 0-2, willing to undergo tumor biopsy, have adequate organ and marrow function, and no prior therapy with PD-1/PD-L1 inhibitors. 39 patients will be enrolled across 6 sites. Patients will receive Avelumab 10 mg/kg IV on days 1 and 15 of each 28-day cycle. Treatment will continue until disease progression, unacceptable toxicity, investigator/patient decision. A newly obtained tumor specimen is required at enrollment; optional biopsy at time of progression. EBV plasma DNA titers will be evaluated at baseline, during treatment and at progression, using an EBV BamHI-W DNA PCR. Blood samples at baseline and 12 weeks after treatment initiation will be obtained for correlatives. Primary endpoint is overall response rate (ORR; complete and partial responses) at 6 months per RECIST. A two-stage design will reject H0 (ORR 15%) if the observed ORR is ≥30%, α 0.1, β 0.8, required sample size n = 39. Secondary endpoints include duration of response, progression-free and overall survival. Correlative analyses will evaluate PD-L1 expression, T and B-cell subsets, frequency and clonality. The study has accrued 2 of planned 39 patients. NCT02875613. Clinical trial information: NCT02875613.