Pembro In Pts Research Articles

Safety of tabelecleucel with pembrolizumab in recurrent/metastatic Epstein–Barr virus-associated nasopharyngeal carcinoma.

6096 Background: Despite standard treatment with radiation and/or chemotherapy, approximately one in four patients (pts) with nasopharyngeal carcinoma (NPC) will develop recurrent/metastatic (RM) disease that is associated with poor prognosis. Programmed cell death ligand 1 (PD-L1) expression is upregulated in NPC due to Epstein–Barr virus (EBV) activation. Tabelecleucel (tab-cel), an off-the-shelf, allogeneic, EBV-specific T-cell immunotherapy, has shown promising antitumor activity in pts with RM EBV+NPC (Prockop, JCO 2016). The anti-PD-1 antibody pembrolizumab (pembro) is also active in NPC. To characterize the safety profile and preliminary efficacy of tab-cel combined with pembro in RM EBV+NPC, we initiated a phase 1b/2 study (NCT03769467). Here we report safety outcomes in 12 subjects treated in the phase 1b portion of the study. Methods: The multicenter, open-label, single-arm phase 1b portion of the study was designed to evaluate the safety of tab-cel in combination with pembro in pts with incurable RM EBV+NPC previously treated with platinum-containing therapy. Pts were either checkpoint-inhibitor naïve (n=6) or experienced to anti-PD-1/PD-L1 therapy (n=6). Tab-cel was administered intravenously (IV) on days 1, 8, and 15 of a 21-day cycle. Initial tab-cel dose was 2x106 cells/kg. Pembro was administered at 200 mg IV Q3W. Primary endpoints of phase 1b focused on assessing safety. Results: As of the final data cutoff, 12 subjects were treated as part of the phase 1b portion of the study. Subjects were 75% Asian and 50% male, with a median age (min, max) of 51 (20, 72) years and a median time from initial diagnosis to first dose of tab-cel (min, max) of 47.7 (8.0, 221.8) months. All subjects had received prior platinum-based chemotherapy/chemoradiation. No dose-limiting toxicities or fatal treatment-emergent adverse events (TEAEs) were identified. All 12 subjects reported ≥1 TEAE; the most common TEAEs reported by ≥4 subjects were disease progression (8 subjects, 66.7%), myalgia (5 subjects, 41.7%), pyrexia, arthralgia, and hyponatremia (4 subjects, 33.3%, each). No ≥ grade 3 TEAEs were considered related to tab-cel or pembro. No TEAEs considered related to tab-cel or pembro led to study discontinuation. No clinically significant abnormal trends were identified in laboratory parameters or vital signs. Although the phase 1b portion of the study was not designed to assess efficacy, the best response seen was stable disease in 6 of 12 pts (50%). Conclusions: Phase 1b data demonstrated combination therapy of tab-cel and pembro to be well tolerated and identified a recommended phase 2 dose in subjects with platinum-pretreated RM EBV+NPC. The study was discontinued after the phase Ib portion due to an evolving immunotherapy treatment landscape for this disease, which would need to be considered for further clinical development. Clinical trial information: NCT03769467 .

The phase 3 INTerpath-002 study design: Individualized neoantigen therapy (INT) V940 (mRNA-4157) plus pembrolizumab vs placebo plus pembrolizumab for resected early-stage non–small-cell lung cancer (NSCLC).

TPS8116 Background: Pembrolizumab (pembro; anti–PD-1) is indicated as adjuvant monotherapy following resection and adjuvant chemotherapy in patients (pts) with stage IB (T2a ≥4 cm), II, or IIIA NSCLC (per AJCC v7). However, many pts experience disease recurrence, and have limited treatment options available. V940 (mRNA-4157) is a novel individualized neoantigen therapy that encodes up to 34 neoantigens that is specifically tailored and manufactured for each pt derived from their tumor. V940 as monotherapy and in combination with pembro has shown preliminary antitumor activity in the phase 1 KEYNOTE-603 study in several solid tumor types, including NSCLC. Additionally, in pts with completely resected, high-risk stage IIIB/C/D and IV cutaneous melanoma in the KEYNOTE-942 primary analysis, V940 plus pembro demonstrated significant improvements in recurrence-free survival (HR, 0.561 [95% CI, 0.309–1.017]; P = 0.0266) and distant metastasis-free survival (HR, 0.347 [95% CI, 0.145–0.828]; P = 0.0063) vs pembro alone. Here we present the design of the phase 3, randomized, double-blind INTerpath-002 study (NCT06077760) of adjuvant V940 plus pembro vs placebo plus pembro in pts with completely resected and chemotherapy-treated stage II–IIIB (N2) NSCLC (AJCC v8). Methods: Eligible pts aged ≥18 years with completely resected stage II, IIIA, or IIIB (N2) squamous or nonsquamous NSCLC (per AJCC v8.0) where EGFR-directed therapy is not indicated as primary therapy (ie, absence of sensitizing EGFR mutations e.g. DEL19 or L858R), who have received 1–4 doses of adjuvant platinum-doublet chemotherapy, have ECOG PS 0 or 1, and have available tumor tissue for next-generation sequencing and PD-L1 testing will be enrolled. Pts must not have received previous neoadjuvant therapy for NSCLC and must not have received or be candidates for adjuvant radiotherapy. Pts will be randomized 1:1 to receive V940 1 mg IM or placebo Q3W for up to 9 doses plus pembro 400 mg IV Q6W for up to 9 cycles or until disease recurrence, pt withdrawal, unacceptable toxicity, or an additional malignancy requiring treatment. Randomization will be stratified by histology (squamous vs nonsquamous), PD-L1 TPS ( < 1% vs 1%–49% vs ≥50%), disease stage (II vs III), and geographic location (North America/Western Europe/Australia vs rest of world). The primary endpoint is disease-free survival per investigator review. Secondary endpoints include distant metastasis-free survival per investigator assessment, OS, lung cancer‒specific survival, patient-reported outcomes, and safety. Tumor imaging will occur at baseline, every 12 wk until wk 48, every 24 wk through year 3, and every 48 wk thereafter. Enrollment began in October 2023 and is ongoing globally (NCT06077760). The abstract was originally presented and published in: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT281. Clinical trial information: NCT06077760 .

Abstract CT114: Phase 1 study of the anti-immunoglobulin-like transcript 4 (ILT4) monoclonal antibody MK-4830 plus pembrolizumab in patients with previously untreated advanced head and neck squamous cell carcinoma (HNSCC) or non-small cell lung cancer (NSCLC)

Abstract Background: ILT4 is an immunosuppressive receptor commonly expressed on myeloid cells. Antagonism of ILT4 may induce a proinflammatory state and stimulate antitumor T-cell response, especially with PD-(L)1 blockade. In the dose escalation phase of a first-in-human phase 1 study (NCT03564691), the anti-ILT4 IgG4 monoclonal antibody, MK-4830, in combination with pembrolizumab (pembro) was well tolerated and demonstrated antitumor activity in advanced solid tumors. Here, we present safety, efficacy, and biomarker analyses for MK-4830 + pembro from the multi-cohort expansion phase of patients (pts) with previously untreated advanced HNSCC or NSCLC. Methods: Pts aged ≥18 y with previously untreated advanced HNSCC and PD-L1 combined positive score (CPS) ≥1 (cohort D) or NSCLC regardless of PD-L1 status (cohorts E and F) were enrolled. Pts in all cohorts received either MK-4830 800 mg (cohorts D and E) or 1600 mg (cohort F) + pembro 200 mg Q3W for ≤35 cycles. Primary end points were safety and ORR per RECIST v1.1 by investigator assessment. Exploratory end points included DOR and PFS per RECIST v1.1 by investigator assessment and evaluating possible biomarkers of response to MK-4830 + pembro. Results: At data cut-off (September 27, 2023), 35, 47, and 11 pts were enrolled and received treatment in cohorts D, E, and F, respectively. Median study follow-up was 34.4 mo (range, 26.5-42.4) in cohort D, 35.9 mo (22.4-39.8) in cohort E, and 38.7 mo (37.6-39.6) in cohort F. Adverse events (AEs) occurred in 33 pts (94%) in cohort D, 43 pts (91%) in cohort E, and 10 pts (91%) in cohort F. Treatment-related AEs (TRAEs) occurred in 20 pts (57%) in cohort D, 26 pts (55%) in cohort E, and 6 pts (55%) in cohort F; grade 3-5 TRAEs occurred in 5 pts (14%), 4 pts (9%), and 1 pt (9%), respectively. One pt in cohort E and 1 pt in cohort F died due to a TRAE (pneumonitis and pneumonia, respectively). ORR was 24% (95% CI, 11-41) in cohort D, 30% (17-45) in cohort E, and 27% (6-61) in cohort F. Median DOR was 16.4 mo (range, 2.2+ to 24.4+) in cohort D, 14.8 mo (4.2+ to 32.9+) in cohort E, and 8.4 mo (3.0-21.5) in cohort F. Median PFS was 5.2 mo (95% CI, 2.0-8.0) in cohort D, 4.3 mo (1.8-8.1) in cohort E, and 3.3 (1.2-7.6) in cohort F. In cohort D, T-cell-inflamed gene expression profile (TcellinfGEP) and tumor mutational burden (TMB) did not enrich for response to MK-4830 + pembro. In cohorts E and F, PD-L1 tumor proportion score (TPS) and TcellinfGEP trended higher in pts with response to MK-4830 + pembro than pts with no response; TMB did not trend with response. Conclusions: In pts with advanced HNSCC or NSCLC, first-line MK-4830 + pembro had a manageable AE profile with modest antitumor activity. Consistent with what was previously observed for pembro alone, a trend was observed between PD-L1 TPS and response to MK-4830 + pembro in pts with NSCLC. Citation Format: Byoung Chul Cho, John Hilton, Cristina P. Rodriguez, Marcelo Bonomi, Lillian L. Siu, Marta Gil-Martin, Shabana Siddiqi, Nicole M. Myer, Leah Suttner, Douglas Wilson, Omobolaji Akala, Rafal Dziadziuszko. Phase 1 study of the anti-immunoglobulin-like transcript 4 (ILT4) monoclonal antibody MK-4830 plus pembrolizumab in patients with previously untreated advanced head and neck squamous cell carcinoma (HNSCC) or non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT114.

Abstract CT281: The phase 3 INTerpath-002 study design: Individualized neoantigen therapy (INT) V940 (mRNA-4157) plus pembrolizumab vs placebo plus pembrolizumab for resected early-stage non-small-cell lung cancer (NSCLC)

Abstract Background: Pembrolizumab (pembro; anti-PD-1) is indicated as adjuvant monotherapy following resection and adjuvant chemotherapy in patients (pts) with stage IB (T2a ≥4 cm), II, or IIIA NSCLC (per AJCC v7). However, many pts experience disease recurrence, and have limited treatment options available. V940 (mRNA-4157) is a novel individualized neoantigen therapy that encodes up to 34 neoantigens that is specifically tailored and manufactured for each pt derived from their tumor. V940 as monotherapy and in combination with pembro has shown preliminary antitumor activity in the phase 1 KEYNOTE-603 study in several solid tumor types, including NSCLC. Additionally, in pts with completely resected, high-risk stage IIIB/C/D and IV cutaneous melanoma in the KEYNOTE-942 primary analysis, V940 plus pembro demonstrated significant improvements in recurrence-free survival (HR, 0.561 [95% CI, 0.309-1.017]; P = 0.0266) and distant metastasis-free survival (HR, 0.347 [95% CI, 0.145-0.828]; P = 0.0063) vs pembro alone. Here we present the design of the phase 3, randomized, double-blind INTerpath-002 study (NCT06077760) of adjuvant V940 plus pembro vs placebo plus pembro in pts with completely resected and chemotherapy-treated stage II-IIIB (N2) NSCLC (AJCC v8). Methods: Eligible pts aged ≥18 years with completely resected stage II, IIIA, or IIIB (N2) squamous or nonsquamous NSCLC (per AJCC v8.0) where EGFR-directed therapy is not indicated as primary therapy (ie, absence of sensitizing EGFR mutations e.g. DEL19 or L858R), who have received 1-4 doses of adjuvant platinum-doublet chemotherapy, have ECOG PS 0 or 1, and have available tumor tissue for next-generation sequencing and PD-L1 testing will be enrolled. Pts must not have received previous neoadjuvant therapy for NSCLC and must not have received or be candidates for adjuvant radiotherapy. Pts will be randomized 1:1 to receive V940 1 mg IM or placebo Q3W for up to 9 doses plus pembro 400 mg IV Q6W for up to 9 cycles or until disease recurrence, pt withdrawal, unacceptable toxicity, or an additional malignancy requiring treatment. Randomization will be stratified by histology (squamous vs nonsquamous), PD-L1 TPS (<1% vs 1%-49% vs ≥50%), disease stage (II vs III), and geographic location (North America/Western Europe/Australia vs rest of world). The primary endpoint is disease-free survival per investigator review. Secondary endpoints include distant metastasis-free survival per investigator assessment, OS, lung cancer‒specific survival, patient-reported outcomes, and safety. Tumor imaging will occur at baseline, every 12 wk until wk 48, every 24 wk through year 3, and every 48 wk thereafter. Enrollment began in October 2023 and is ongoing globally (NCT06077760). Citation Format: Jonathan D. Spicer, Santosh M. Nair, Adnan Khattak, Jay M. Lee, Michelle Brown, Robert S. Meehan, Nazly Shariati, Xuan Deng, Ayman Samkari, Jamie E. Chaft. The phase 3 INTerpath-002 study design: Individualized neoantigen therapy (INT) V940 (mRNA-4157) plus pembrolizumab vs placebo plus pembrolizumab for resected early-stage non-small-cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT281.

Encorafenib (enco) + binimetinib (bini) + pembrolizumab (pembro) for unresectable locally advanced or metastatic BRAF V600-mutant melanoma: Results from STARBOARD safety lead-in (SLI).

9531 Background: BRAF inhibitors (BRAFi) + MEK inhibitors (MEKi) (eg, enco + bini) and immune checkpoint inhibitors (CPIs) (eg, pembro) are approved for patients (pts) with BRAF V600-mutant metastatic melanoma. Combinations of BRAFi + MEKi with CPIs further improve outcomes and may offer additional treatment strategies. STARBOARD (NCT04657991) is an ongoing randomized, double-blinded, placebo-controlled, phase 3 study of enco + bini + pembro vs pembro in pts with unresectable locally advanced or metastatic BRAF V600-mutant cutaneous melanoma. Here we present the SLI results. Methods: Key inclusion criteria were histologically confirmed unresectable/metastatic BRAF V600E/K-mutant cutaneous melanoma and ≤1 prior systemic therapy for unresectable/metastatic disease. Pts received enco 450 mg QD + bini 45 mg BID + pembro 200 mg IV Q3W (COMBO450+P) or enco 300 mg QD + bini 45 mg BID + pembro 200 mg IV Q3W (COMBO300+P). The primary objective was to identify the recommended phase 3 dose (RP3D). The primary endpoint was dose-limiting toxicity (DLT) incidence; secondary endpoints included safety, objective response rate (ORR), time to response (TTR), and PFS (post hoc). Results: 20 pts received COMBO450+P and 17 COMBO300+P (cutoff: Dec 2, 2022). See table for baseline characteristics. 1 pt had a DLT with COMBO450+P: Grade (G) 3 drug-induced liver injury with concurrent G4 ALT increase and G3 bilirubin increase that resolved. 2 pts had DLTs with COMBO300+P: 1 with G3 rheumatoid arthritis flare and 1 with inability to receive drug due to G4 arthralgia, G4 back pain, G4 pyrexia, G3 chills, G3 headache, G3 paranesthesia, and G3 maculopapular rash. Drug-related AEs led to permanent discontinuation in 4, 5, and 6 pts for enco, bini, and pembro, respectively. 1 pt in the COMBO300+P arm died <28 days after discontinuing all study treatments due to disease progression. See table for antitumor activity data. Conclusions: Safety across cohorts was comparable and consistent with the known safety profile of each agent. Both regimens were generally tolerable; COMBO450+P was chosen as the RP3D based on the totality of the safety data. The phase 3 portion of STARBOARD is ongoing. Clinical trial information: NCT04657991 . [Table: see text]

845P Vidutolimod + pembrolizumab as 2L+ treatment in patients with anti–PD-1–refractory melanoma and adrenal insufficiency: Subgroup analyses of a phase Ib study

Corticosteroid replacement therapy (CRT) in patients (pts) with adrenal insufficiency (AI) could reduce the efficacy of immunotherapy. Vidutolimod (vidu) is an immunostimulatory virus-like particle containing a CpG-A Toll like receptor 9 (TLR9) agonist. In a phase 1b study in pts with anti–PD-1–refractory melanoma, vidu + pembrolizumab (pembro) showed promising clinical activity with an objective response rate (ORR) of 23.5% (95% CI, 15.5-33.1). This post hoc analysis assessed the safety and clinical activity in the subgroup of pts with AI on CRT. This study (NCT02680184) enrolled adults with etastatic or unresectable cutaneous melanoma with progressive disease or stable disease after ≥12 weeks of anti−PD-1 treatment (tx), measurable disease per RECIST v1.1, ECOG PS 0/1, and ≥1 lesion accessible for intratumoral (IT) injection. This post hoc analysis included all pts who received IT vidu + IV pembro. Pts with AI were to receive CRT (prednisone-equivalent 5-10 mg daily) and prophylactic stress-dose steroids (50-100 mg hydrocortisone or equivalent orally every 8 hours) before and for 24-48 hours after vidu dosing. The primary objective was safety, and the key secondary objective was ORR. 159 pts received vidu + pembro. All pts had prior anti–PD-1 tx, and 74 pts (46.5%) had prior ipilimumab (ipi) tx. 148 pts (93.1%) had progressive disease on last anti–PD-1 tx. 20 pts (12.6%) had a medical history of AI; 19 of these pts (95.0%) had prior ipi tx. 5 additional pts (3.1%; 4 with prior ipi tx) were diagnosed with AI on study. Grade 3/4 tx-emergent adverse events were reported in 11 pts (55.0%) with prior AI and in 3 pts (60.0%) diagnosed with AI on study. No tx-related deaths occurred. The ORR was 28.0% (7/25; 95% CI, 12.1-49.4) in pts with AI. The safety and ORR of vidu + pembro in pts with AI were consistent with the overall study population, suggesting that simultaneous corticosteroids for AI do not reduce the biologic activity of this combination. A phase 2 study to confirm the efficacy of vidu + anti–PD-1 in pts with PD-1 blockade–refractory melanoma is ongoing (NCT04698187).

Phase 2 study of azacitidine (AZA) plus pembrolizumab (pembro) as second-line treatment in patients with advanced pancreatic ductal adenocarcinoma.

4158 Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related death with a 5-year survival rate of 10%. Novel strategies for advanced PDAC are a critical need. A DNA hypomethylating agent (HMA) increased tumor-infiltrating effector T cells and significantly prolonged survival in combination with immune checkpoint blockade (ICB) in a PDAC mouse model (Gonda et al 2020). We hypothesized that combining HMA with ICB will lead to therapeutic benefit in pts with advanced PDAC. Methods: This is an open-label, single-arm, single-center, Phase 2 trial of AZA plus pembro in pts with unresectable or metastatic PDAC. Pts were treated with AZA 50 mg/m2 subcutaneous daily for 5 days Q4W beginning week 1 day 1 followed by pembro 200 mg IV Q3W starting week 3 day 1. Key eligibility criteria included documented progression on or following first-line systemic treatment, ECOG PS 0-1, and adequate organ function. The primary objective was progression-free survival (PFS). Thirty-one evaluable pts were required to detect an improvement in PFS from 2 mo to 4 mo with a one-sided p-value of 0.05 and 80% power. Secondary endpoints included safety and tolerability, overall response rate (ORR), disease control rate (DCR), and overall survival (OS). Data cutoff was February 10, 2022. Results: Between Oct 2017 and Sept 2021, 36 pts were enrolled (median age 62.5, 75% white, 72% male). At data cutoff, 34 and 31 pts received at least 1 dose of AZA and pembro, respectively. Median PFS for ≥1 dose of AZA was 1.48 mo (95% CI: 1.35, 1.74) and for ≥1 dose of pembro was 1.51 mo (95% CI, 1.38, 3.42). The median OS was 4.67 months. Among the 34 pts, 3 (8.8%) experienced a partial response (PR) by RECIST with a DCR of 32.4%. Of the 3 pts with PR, 2 received 35 doses of pembro and continued beyond 2 years with an ongoing PR. One pt remains on pembro 20 months after study completion. None of the pts with a PR were microsatellite instability-high or tumor mutation burden high, and next-generation sequencing of the 3 cancers identified a BRCA1 variant and POLE variant. Treatment-related AEs (TRAEs) occurred in 20/34 pts (59%), the most common of which were diarrhea and fatigue. Grade ≥3 occurred in 7/34 (21%) including 1 immune-related grade 5 event (encephalitis). Conclusions: AZA plus pembro demonstrated a tolerable safety profile but no PFS benefit compared to historical controls. Our data suggests combined epigenetic therapy and ICB may expand therapeutic options in a subset of pts with PDAC. Further investigation is needed to identify biomarkers to predict response and elucidate effective timing, sequencing, and combination of epigenetic agents. Follow-up for OS is ongoing. Correlative analysis of epigenetic effects and characterization of the tumor immune microenvironment will be reported. Clinical trial information: NCT03264404.

Primary analysis of a phase 2, open-label, multicenter trial of talimogene laherparepvec (T-VEC) plus pembrolizumab (pembro) for the treatment (Tx) of patients (pts) with advanced melanoma (MEL) who progressed on prior anti–PD-1 therapy: MASTERKEY-115.

9518 Background: Despite advances in anti–PD-1–based Tx for MEL, an unmet need remains for immunotherapy failure in advanced metastatic or unresectable MEL. Also, there is a growing population of pts who received adjuvant anti–PD-1 and recurred; yet trials to address this population are lacking. Combination Tx with T-VEC, an oncolytic viral intratumoral Tx designed to produce GM-CSF, and pembro, an anti–PD-1 agent, may overcome immunotherapy failure. We report the MASTERKEY-115 primary analysis on the efficacy and safety of T-VEC + pembro in pts with advanced MEL who had progressive disease (PD) on prior anti–PD-1. Methods: This open-label, single-arm, multicenter, phase 2 study (NCT04068181) enrolled pts at 26 international sites (Jan 2020‒Feb 2021). Cohorts 1 and 2, primary and acquired resistance, respectively, received anti–PD-1 in a locally recurrent or metastatic setting and had PD within 12 wks of the last anti–PD-1 dose. Cohorts 3 and 4 included only pts who received adjuvant anti–PD-1 and were disease-free for < 6 mos (Cohort 3) or ≥ 6 mos (Cohort 4) before confirmed PD. Eligible pts had histologically confirmed unresectable or metastatic stage IIIB–IVM1d MEL, measurable and injectable disease, ECOG PS 0/1, and progressed on anti–PD-1 directly before enrollment. T-VEC at standard dosage and pembro 200 mg were given Q3W. The primary endpoint was objective response rate (ORR). Key secondary endpoints were complete response (CR) rate, progression-free survival (PFS), and safety. Tx decisions were per modified immune-related response criteria (irRECIST). Results: 72 pts (median age, 65 y) were enrolled. Of the 71 evaluable pts, 37 (52.1%) had stage IVM1b‒d disease, 30 (42.3%) had confirmed PD-L1–positive tumor (CPS ≥ 1%), 20 (28.2%) had a BRAFV600 mutation, and 21 (29.6%) had LDH > 1ULN. At data cutoff (Aug 2021), 47 (65.3%) pts remained on study. ORR was 0%, 6.7%, 40%, and 46.7% in cohorts 1–4, respectively (table). Any-grade Tx-related adverse events (TRAEs) were reported in 54 (76.1%) pts; the most common were pyrexia (29.6%), fatigue, and influenza-like illness (15.5% each). Grade ≥ 3 TRAEs occurred in 9 (12.7%) pts. Conclusions: T-VEC + pembro showed manageable safety in pts with advanced MEL after anti–PD-1 failure; the promising ORR observed in pts who progressed on prior adjuvant anti–PD-1 warrants further analysis. Clinical trial information: NCT04068181. [Table: see text]

Abstract CT218: Phase 1/2 study of a novel HER2 targeting TLR7/8 immune-stimulating antibody conjugate (ISAC), BDC-1001, alone and in combination with pembrolizumab (pembro) in patients (pts) with HER2-expressing advanced solid tumors

Abstract Background: To date, anti-HER2 monoclonal antibodies are the only immune therapies approved for treating pts with HER2-over-expressing cancers. Intratumoral delivery of immunostimulatory adjuncts such as toll-like receptor (TLR) 7/8 agonists can activate tumor resident antigen-presenting cells (APCs) to promote antitumor immunity. To optimize intratumoral delivery while leveraging favorable preclinical biology we developed a novel, systemically delivered ISAC (BDC-1001). BDC-1001 consists of an investigational trastuzumab biosimilar chemically conjugated to a TLR 7/8 agonist (payload) with an intervening non-cleavable linker. BDC-1001 activates human myeloid APCs and retains antibody-mediated effector functions such as antibody-dependent cellular cytotoxicity/phagocytosis. Our trastuzumab-based ISACs seem to elicit potent and durable immune-mediated antitumor efficacy including tumor regression in a TLR- and Fc receptor-dependent manner in xenograft and syngeneic tumor resistant models (Ackerman et al. Nat Cancer 2020). BDC-1001 did not induce interstitial lung disease, cytokine release syndrome, or thrombocytopenia in non-human primate studies. A four-part phase 1/2, first-in-human study was initiated in 2020 to evaluate BDC-1001 with or without (±) pembro in pts with HER2-overexpressing or amplified advanced solid tumors. Methods: This phase 1/2 dose-escalation/expansion study will enroll up to 390 pts with HER2-overexpressing (IHC2+ or 3+) or HER2-amplified (by in situ hybridization or next-generation sequencing) advanced solid tumors. Patients may have received prior anti-HER2 therapies. Primary objectives of dose-escalation are safety and tolerability, and establishing a recommended phase 2 dose of BDC-1001 alone administered IV q3w (Part 1) and combined with pembro (Part 2). Primary endpoints of Parts 1 & 2 include assessment of safety and tolerability; dose-limiting immune-related toxicities in a 3+3 design. The dose-expansion phase 2 portion will evaluate preliminary antitumor activity of BDC-1001 alone (Part 3) and with pembro (Part 4) using RECIST v1.1 and iRECIST. The primary endpoint of the phase 2 is best\ overall response rate; with secondary endpoints of duration of response, disease control rate, and progression-free survival. Exploratory objectives include pharmacokinetic parameters and pharmacodynamic biomarkers associated with drug exposure to help elucidate mechanism of action and identify biomarkers to improve selection of pts most likely to benefit from the single therapy or combination. Recruitment is ongoing (NCT04278144). Citation Format: Manish R. Sharma, Richard D. Carvajal, Daniel Catenacci, Leisha A. Emens, Glenn J. Hanna, Dejan Juric, Yoon-Koo Kang, Jeeyun Lee, Keun-Wook Lee, Bob T. Li, Kathleen Moore, Mark D. Pegram, Paula R. Pohlmann, Drew Rasco, Alexander Spira, Arielle L. Heeke, Ding Wang, Lawrence Garbo, Sudhir Manda, Jasgit Sachdev, Shelley E. Ackerman, Heidi LeBlanc, David Dornan, Marcin Kowanetz, Michael N. Alonso, Amreen Husain, Edith A. Perez, Ecaterina Ileana Dumbrava. Phase 1/2 study of a novel HER2 targeting TLR7/8 immune-stimulating antibody conjugate (ISAC), BDC-1001, alone and in combination with pembrolizumab (pembro) in patients (pts) with HER2-expressing advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT218.

Abstract CT139: Intratumoral oncolytic virus V937 in combination with pembrolizumab (pembro) in patients (pts) with advanced melanoma: Updated results from the phase 1b CAPRA study

Abstract Background: Coxsackievirus A21 (V937) is an RNA oncolytic virus targeting ICAM-1 receptors. Pharmacodynamic effects of oncolytic viruses in the tumor microenvironment (TME), including increased CD8+ T cells and PD-L1 expression, support their use in combination with checkpoint inhibitors. We present updated clinical and correlative data from the multicenter phase 1b CAPRA study (NCT02565992) of V937 + pembro in pts with advanced melanoma. Methods: Eligible pts had metastatic/unresectable stage IIIB-IV melanoma and ≥1 cutaneous/subcutaneous tumor or lymph node amenable to V937 intratumoral injection. Pts received V937 on days 1, 3, 5, and 8; then Q3W for up to 19 injections (maximum dose, 3 × 108 50% TCID50). Pts received IV pembro 2 mg/kg Q3W on day 8, continuing for up to 2 y. Primary endpoints were incidence of AEs, serious AEs (SAEs), and dose-limiting toxicities (DLTs). Secondary endpoints were ORR, duration of response (DOR), PFS, and OS. Biomarkers were an exploratory endpoint. Results: 36 pts were enrolled (mean age, 68.5 y; 75% male; 22% had prior immunotherapy). As of 4 Nov 2019, median (range) time from first dose to data cutoff was 32.0 (10.7−45.3) mo. No DLTs occurred. Grade 3-5 treatment-related AEs occurred in 5 (14%) pts. 3 (8%) pts had treatment-related SAEs (autoimmune encephalitis and septic shock in 1 pt, keratoacanthoma, autoimmune hepatitis); 1 died from septic shock. Efficacy results included ORR of 47% (CR, 22%; PR, 25%; Table 1). In comparing responders vs nonresponders, baseline tumor samples showed no difference in PD-L1 expression and lower CD3+CD8- infiltrate in responders. Conclusions: V937 + pembro had manageable safety and promising efficacy in pts with advanced melanoma. Response was not associated with an inflamed TME at baseline, indicating that V937 may induce an immune responsive TME. The combination is being studied in the neoadjuvant setting in pts with stage III melanoma (KEYMAKER-U02). Table 1.Efficacy OutcomesV937 + Pembro (N = 36)ORR,a % (95% CI)b47 (30-65)- CR22 (10-39)- PR25 (12-42)DOR,c median (range), moNR (1.4+ to 22.0+)PFS,c,d median (95% CI), mo11.9 (3.4-NR)12-mo PFS,c % (95% CI)45 (28-60)OS,c median (95% CI), mo30.9 (20.3-40.5)12-mo OS,c % (95% CI)85 (68-94)+ indicates no PD by the time of last disease assessment. NR, not reached.aBest overall response with confirmation based on investigator assessment per immune-related response criteria; imaging was performed Q6W.bBased on the exact method for binomial data.cKaplan-Meier estimate.dBased on investigator assessment per immune-related response criteria. Citation Format: Ann W. Silk, Steven J. O'Day, Howard L. Kaufman, Jennifer Bryan, Jacqueline T. Norrell, Casey Imbergamo, Daniella Portal, Edwin Zambrano-Acosta, Marisa Palmeri, Seymour Fein, Cai Wu, Leslie Guerreiro, Daniel Medina, Praveen K. Bommareddy, Andrew Zloza, Bernard A. Fox, Carmen Ballesteros-Merino, Darren Shafren, Mark Grose, Joshua A. Vieth, Janice M. Mehnert. Intratumoral oncolytic virus V937 in combination with pembrolizumab (pembro) in patients (pts) with advanced melanoma: Updated results from the phase 1b CAPRA study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT139.

Phase 1/2 study of eprenetapopt (APR-246) in combination with pembrolizumab in patients with solid tumor malignancies.

TPS3161 Background: The p53 pathway has been implicated in antitumor immunity, including antigen presentation and T-cell proliferation. Loss of p53 function can increase resistance to immunotherapy across many tumor types. Eprenetapopt (eprenet) is a small molecule that stabilizes the folded structure of p53, resulting in activation of mutant p53 and stabilization of wild-type (WT) p53. It also targets the cellular redox homeostasis, resulting in induction of apoptosis in tumor cells. In vivo, mice carrying supernumerary copies of the TP53 gene harbor a pro-inflammatory tumor microenvironment, an effect recapitulated in TP53 normal-copy mice treated with eprenetapopt. Combining eprenetapopt and anti-PD1 or anti-CTLA4 therapy resulted in enhanced tumor growth inhibition and improved survival in TP53 WT mice inoculated with B16 melanoma and MC38 colon adenocarcinoma cells . Based on these results, we hypothesized that eprenet-induced p53 stabilization may augment response to immunotherapy. To test this hypothesis, we are conducting a phase 1b/2 study of eprenet in combination with pembrolizumab (eprenet+pembro) in pts with solid tumors. Methods: The primary objectives are to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) and to assess the safety and tolerability of eprenet+pembro in pts with advanced solid tumors. The secondary objectives are to estimate the anti-tumor activity and to describe the pharmacokinetics of the combination. Exploratory objectives include assessing predictive and pharmacodynamic markers of response. The study includes a safety lead-in with a 3+3 dose de-escalation design for pts with advanced solid tumors with known tumor TP53 mutation status ( TP53 WT is acceptable) (max 18 pts), followed by expansion cohorts in pts with NSCLC, gastric/GEJ and urothelial cancer (max 100 pts). In expansion, pts with urothelial and gastric cancers must be naïve to anti-PD-1/ L1 therapy. Eprenet is given IV once daily on Days 1–4 while pembro is administered on Day 3 of each 21-day cycle. The RP2D of eprenet+pembro is considered the dose at which ≤ 1 of 6 pts in a cohort has a dose-limiting toxicity (DLT). Primary endpoints are occurrence of DLTs, adverse events (AEs) and serious AEs with eprenet+pembro. Key secondary endpoints are best objective response, progression free survival and overall survival. Exploratory endpoints include gene mutations by next generation sequencing (including TP53), mRNA expression, multiplex immunohistochemistry and transcriptomics, multiplex flow cytometry on peripheral blood mononuclear cells and cytokines in serum. Continuous monitoring of toxicity will be conducted. The trial opened in May 2020 and is actively enrolling patients. Clinical trial information: NCT04383938.

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.

Safety and efficacy of tisagenlecleucel (tisa-cel) plus pembrolizumab (pembro) in patients (pts) with relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL): Updated analysis of the phase 1b PORTIA study.

e19537 Background: Tisa-cel showed durable responses and manageable safety in pts with r/r DLBCL in the phase 2 JULIET trial. High baseline programmed cell death 1 (PD-1) expression associated with higher probability of no response (Schuster et al. NEJM 2019). Here we report an updated analysis of PORTIA, a phase 1b, multicenter, open-label study of tisa-cel plus pembro in pts with r/r DLBCL. Methods: Eligible pts (≥18 y) had r/r DLBCL after ≥2 lines of therapy and relapsed after or were not candidates for autologous stem cell transplant (autoSCT). Patients received a single tisa-cel infusion on Day 1 and were enrolled in 1 of 3 cohorts that initiated pembro (200 mg q 21 days, for up to 6 doses) on either Days +15, +8, or –1. Primary endpoints were incidence of dose-limiting toxicities (DLTs) and overall response rate (ORR; complete response [CR] and partial response [PR]). Secondary endpoints included duration of response, progression-free survival, overall survival, safety, and cellular kinetics. Results: As of November 9, 2020, 15 pts were enrolled and 12 received tisa-cel (n = 4 pts for each Days +15, +8, and –1 cohorts; median follow-up, 4 mo). At study entry, the median age among treated pts was 62 y (range, 35-79), 100% had an International Prognostic Index score ≥2, 67% had ≥3 prior lines of therapy, 58% had stage IV disease, 58% had lactate dehydrogenase > ULN, and 42% had prior autoSCT. All 12 pts had ≥1 AE. Grade ≥3 AEs suspected to be related to tisa-cel and/or pembro were neutropenia (n = 4); neutrophil count decreased (n = 3); febrile neutropenia, lymphocyte count decreased, malnutrition (each n = 2); anemia, leukopenia, diarrhea, white blood count decreased, liver function tests increased, thrombocytopenia, hepatitis, and cytokine release syndrome (CRS; each n = 1). No neurotoxicity or DLTs were observed. Among the Day +15, +8, and –1 cohorts (each n = 4), the ORR was 50% (2/4; CR n = 0, PR n = 2), 25% (1/4; CR n = 1, PR n = 0), and 25% (1/4; CR n = 1, PR n = 0; longer follow-up is needed for n = 2 pts), respectively. Tisa-cel exposure and peak expansion were consistent with JULIET, with a trend toward delayed expansion in the Day –1 cohort (n = 4). There was no sign of secondary expansion following pembro administration regardless of the number of doses. Compared with JULIET, lower CRS severity and frequency and lower cytokine profiles were observed for all 3 cohorts. Conclusions: The combination of tisa-cel plus pembro was feasible and showed manageable safety. The lack of improved efficacy in PORTIA with the addition of pembro compared with tisa-cel alone may be related to more pts with ≥3 prior lines of therapy (67% vs 51%, respectively), and/or pts with more advanced disease in PORTIA. Additional studies with larger patient cohorts are needed to determine the value of adding PD-1 inhibitors to CAR-T cell therapy in pts with r/r DLBCL. Clinical trial information: NCT03630159.

A phase 1 first-in-human study of the anti-LAG-3 antibody MK4280 (favezelimab) plus pembrolizumab in previously treated, advanced microsatellite stable colorectal cancer.

3584 Background: Patients (pts) with microsatellite stable (MSS) metastatic colorectal cancer (mCRC) that progressed on ≥2 prior therapies have limited treatment options, with median OS ranging from 6-9 months (mo). In the dose-escalation phase of this first-in-human multicohort study (NCT02720068), the anti-lymphocyte activation gene (LAG)-3 antibody favezelimab (fave) was well tolerated alone and with pembrolizumab (pembro) across all dose levels (Lakhani, SITC, 2018, abstract O26). Here, we evaluate the safety and efficacy of fave alone or in combination with pembro in pts with advanced MSS CRC from the dose confirmation phase. Methods: Eligible pts with MSS PD-1/PD-L1-treatment-naïve mCRC that progressed on prior standard-of-care (3L+) were enrolled (cohort A) to receive the RP2D of 800 mg fave alone (Arm 1), 800 mg fave + 200 mg pembro (Arm 2C), or 800 mg fave + 200 mg pembro (MK-4280A) co-formulation (Arm 5), all Q3W. Treatment continued for 35 cycles or until progression, unacceptable toxicity, or investigator/pt decision. Pts with confirmed progression per irRECIST v1.1 on fave alone could crossover to 800 mg fave + pembro. Safety was assessed in all treated pts; efficacy in the full analysis set (FAS) of all treated pts with baseline scan. Objectives included safety (primary), ORR (RECIST v1.1 by investigator [secondary]), and DOR, PFS, and OS (exploratory). Interim analysis data cut-off was: Oct. 23, 2020. Results: A total of 20 pts received fave (Arm 1); 89 pts (including 9 crossover) received fave + pembro (Arms 2C+5); 12 pts (Arm 1) and 36 pts (Arms 2C+5), had PD-L1 CPS ≥1 tumors. At data cut-off, median follow-up was 5.8 months (mo) in Arm 1 and 6.2 mo in Arms 2C+5. Treatment-related adverse events (TRAEs) were 65% with fave (Arm 1) and 65.2% with fave + pembro (Arms 2C+5). Grade ≥3 TRAEs were 15% (Arm 1), and 20% [Arms 2C+5]). No grade 5 TRAEs were reported. Common TRAEs (≥15%) included fatigue (20.0%), nausea (15%) with fave, and fatigue (16.9%) with fave + pembro. Confirmed ORR was 6.3% (4PR, 1CR) with fave + pembro (Arms 2C+5). No pt receiving fave alone responded. In Arms 2C+5, median DOR was 10.6 mo (range, 5.6-12.7). ORR, OS and PFS by PD-L1 status are reported in the Table. Conclusions: Favezelimab alone or in combination with pembrolizumab had a manageable safety profile, with no treatment-related deaths. Promising antitumor activity was observed with combination therapy, including with MK-4280A, compared with monotherapy most notably in pts with PD-L1 CPS ≥1 tumors. Clinical trial information: NCT02720068. [Table: see text]

LEAP-005: A phase 2 multicohort study of lenvatinib plus pembrolizumab in patients with previously treated selected solid tumors—Results from the colorectal cancer cohort.

3564 Background: Pembrolizumab (pembro), an anti-PD-1 antibody, is approved for the treatment of patients (pts) with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair (MMR) deficient colorectal cancer, both as first-line treatment and after progression following treatment with fluoropyrimidine, oxaliplatin, and irinotecan. The combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, and anti-PD-1 treatment showed synergistic antitumor activity in preclinical models. LEAP-005 (NCT03797326) is evaluating the efficacy and safety of lenvatinib plus pembro in pts with previously treated advanced solid tumors. We present findings from the colorectal cancer cohort. Methods: In this nonrandomized, open-label, phase 2 study, adult pts (aged ≥18 y) with histologically/cytologically documented metastatic and/or unresectable colorectal cancer, non–MSI-H/pMMR tumor per local determination, previous treatment with oxaliplatin and irinotecan in separate lines of therapy, measurable disease per RECIST v1.1, ECOG PS of 0‒1, and a tissue sample evaluable for PD-L1 expression were eligible. Pts received lenvatinib 20 mg QD plus pembro 200 mg Q3W for up to 35 cycles of pembro (̃2 y) or until confirmed disease progression, unacceptable toxicity, or withdrawal of consent. Treatment with lenvatinib could continue beyond 2 y in pts with clinical benefit. Primary endpoints were ORR (per RECIST v1.1 by blinded independent central review) and safety. Secondary endpoints included disease control rate (DCR), duration of response (DOR), PFS, and OS. Tumor imaging was performed Q9W from treatment initiation for 54 wks, then Q12W to week 102, and Q24W thereafter. Results: 32 pts with colorectal cancer received treatment with lenvatinib plus pembro (median age, 56 y [range, 36-77]; male, 81%; 3L, 91%); median time from first dose to data cutoff (April 10, 2020) was 10.6 mo (range, 5.9-13.1). ORR was 22% (95% CI, 9–40; table). Grade 3–5 treatment-related AEs occurred in 16 (50%) pts. Treatment-related AEs led to treatment discontinuation in 3 pts (grade 2 ischemic stroke [n = 1], grade 3 increased liver transaminases [n = 1], grade 5 intestinal perforation [n = 1]). Conclusions: In pts with previously treated advanced non–MSI-H/pMMR colorectal cancer, lenvatinib plus pembro demonstrated promising antitumor activity and a manageable safety profile. Enrollment in the colorectal cohort was expanded to 100 pts. Clinical trial information: NCT03797326. [Table: see text]

Safety, pharmacokinetics, pharmacodynamics profiles and preliminary antitumor activity of phase 1b/2a study of NT-I7, a long-acting interleukin-7, plus pembrolizumab in patients with advanced solid tumors: The phase 1b data report.

2594 Background: NT-I7 (efineptakin alfa) is the first-in-class long-acting IL-7 which can increase the number and functionality of T cells in the peripheral blood (PB) of patients (pts). The combination of NT-I7 and pembrolizumab (pembro), a PD-1 Checkpoint Inhibitor (CPI), may augment and broaden the efficacy of CPIs. Methods: This is an open-label, phase 1b/2a study in pts with relapsed/refractory (R/R) advanced solid tumors. In the phase 1b (Dose Escalation), which followed the 3+3 design, pts received NT-I7 intramuscularly (IM) at 3 dose levels (DLs): 480, 960, and 1200 µg/kg every 6 weeks (Q6W) plus pembro 200 mg intravenously (IV) Q3W. The objectives of the phase 1b were to evaluate Dose Limiting Toxicity (DLT), determine the Maximum Tolerated Dose (MTD) and/or the Recommended Phase 2 Dose (RP2D), and assess pharmacokinetics (PK), pharmacodynamics, and preliminary antitumor activity. Results: As of 12 January 2021, 12 pts were enrolled in the phase 1b: DL1 (n=3), DL2 (n=3) and DL3 (n=6). Median age 58.0 years [43-77], ECOG PS 0 (50%), PS 1 (50%), median number of prior therapies 4 [1-8]. MTD was not reached. One DLT (Grade [G] 3 ALT increased) was reported in DL3. Treatment-related adverse events (AEs) occurred in 11 (91.7%) pts, 11 (91.7%) G1-2 and 4 (33.3%) G3; no G4 or G5 AEs reported. Common treatment-emergent AEs were injection site reaction (n=8, 66.7%), chills (n=7, 58.3%), nausea (n=6, 50%) and pyrexia (n=6, 50%). Preliminary PK analysis showed Tmax = 24 hours and T1/2 = 123 hours for NT-I7 at DL3. NT-I7 + pembro induced dose-dependent lymphocyte proliferation in the PB, with ̃ 3-fold increase at DL3, and a corresponding decrease in neutrophil to lymphocyte ratio at 14 days after the 1st treatment. Importantly, increased number of T cells in the tumor microenvironment (TME) was also observed (Table). One pt with metastatic mucosal melanoma who had not responded to prior combination of nivolumab and ipilimumab had a rapid, confirmed partial response with 46% tumor reduction. Patient follow-up continues and updated data will be presented. The combination of NT-I7 1200 µg/kg IM Q6W + pembro 200 mg IV Q3W has been selected as the RP2D. Conclusions: The combination of NT-I7 + pembro was well tolerated in pts with R/R advanced solid tumors. NT-I7 + pembro significantly increased T cell numbers in both the TME and the PB, and there was encouraging antitumor activity with the combination in this pt population. These results support continued evaluation of NT-I7 in combination with pembro in pts with R/R advanced solid tumors. The phase 2a of the study is enrolling pts with either CPI-pretreated or CPI-naïve solid tumors (NCT04332653). Clinical trial information: NCT04332653. [Table: see text]

LEAP-005: A phase II multicohort study of lenvatinib plus pembrolizumab in patients with previously treated selected solid tumors—Results from the colorectal cancer cohort.

94 Background: Pembrolizumab (pembro), an anti-PD-1 antibody, is approved for the treatment of patients (pts) with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair (MMR) deficient colorectal cancer, both as first-line treatment and after progression following treatment with fluoropyrimidine, oxaliplatin, and irinotecan. The combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, and anti-PD-1 treatment showed synergistic antitumor activity in preclinical models. LEAP-005 (NCT03797326) is evaluating the efficacy and safety of lenvatinib plus pembro in pts with previously treated advanced solid tumors. We present findings from the colorectal cancer cohort. Methods: In this nonrandomized, open-label, phase 2 study, adult pts (aged ≥18 y) with histologically/cytologically documented metastatic and/or unresectable colorectal cancer, non–MSI-H/pMMR tumor per local determination, previous treatment with oxaliplatin and irinotecan in separate lines of therapy, measurable disease per RECIST v1.1, ECOG PS of 0‒1, and a tissue sample evaluable for PD-L1 expression were eligible. Pts received lenvatinib 20 mg QD plus pembro 200 mg Q3W for up to 35 cycles of pembro (~2 y) or until confirmed disease progression, unacceptable toxicity, or withdrawal of consent. Treatment with lenvatinib could continue beyond 2 y in pts with clinical benefit. Primary endpoints were ORR (per RECIST v1.1 by blinded independent central review) and safety. Secondary endpoints included disease control rate (DCR), duration of response (DOR), PFS, and OS. Tumor imaging was performed Q9W from treatment initiation for 54 wks, then Q12W to week 102, and Q24W thereafter. Results: 32 pts with colorectal cancer received treatment with lenvatinib plus pembro (median age, 56 y [range, 36-77]; male, 81%; 3L, 91%); median time from first dose to data cutoff (April 10, 2020) was 10.6 mos (range, 5.9-13.1) ORR was 22% (95% CI, 9-40; Table). Grade 3-5 treatment-related AEs occurred in 16 (50%) pts. Treatment-related AEs led to treatment discontinuation in 3 pts (grade 2 ischemic stroke [n = 1], grade 3 increased liver transaminases [n = 1], grade 5 intestinal perforation [n = 1]). Efficacy Results. Clinical trial information: NCT03797326. NR, not reached aConfirmation was not required for best overall response of SD, but a final visit response of SD or better must have occurred ≥6 wks after starting study treatment Conclusions: In pts with previously treated advanced non–MSI-H/pMMR colorectal cancer, lenvatinib plus pembro demonstrated promising antitumor activity and a manageable safety profile. Enrollment in the colorectal cohort was expanded to 100 pts. [Table: see text]

Abstract 2009: Evaluation of RNA-sequencing signatures with response to pembrolizumab (pembro) monotherapy in ipilimumab-naive patients (pts) with melanoma

Abstract Introduction: KEYNOTE-001 (NCT01295827) was a phase 1 study of pembro in pts with locally advanced or metastatic melanoma (parts B and D). KEYNOTE-006 (NCT01866319) was a randomized phase 3 study of pembro vs ipilimumab in pts with advanced melanoma. We explored potential relationships between key tumor microenvironment canonical signatures beyond T cell-inflamed gene expression profile (GEP) and response/resistance to pembro monotherapy in pts with melanoma. Methods: In pembro-treated, ipilimumab-naive pts from KEYNOTE-001 and KEYNOTE-006 with available RNA-sequencing and clinical data (n = 476), we analyzed association of 9 non-T cell-inflamed GEP canonical signatures (angiogenesis, gMDSC, glycolysis, hypoxia, Myc, proliferation, RAS, stromal/EMT/TGFβ, WNT) with clinical outcomes. Signatures were defined with TCGA and Moffitt databases (independent of any pembro trial) using a correlation algorithm to select individual genes for membership in the canonical signature based on correlation with reference signatures identified in literature or internal work. Relationships between RNA signatures and clinical outcomes were assessed using 2 models: 1 adjusted for ECOG PS and batch effect and 1 adjusted for T cell-inflamed GEP to understand the additional explanatory value of a non-T cell-inflamed GEP signature for clinical outcomes. P values were adjusted for multiplicity; significance was predefined at α = 0.05. Database cutoffs for clinical data: 11/27/2017 (KEYNOTE-001), 12/4/2017 (KEYNOTE-006). Results: T cell-inflamed GEP was statistically significantly associated with response to pembro (P < 0.0001). No canonical signatures showed statistically significant association with response/resistance to pembro after multiplicity adjustment when adjusting for T cell-inflamed GEP, ECOG PS, and batch effect. Without adjusting for T cell-inflamed GEP, Myc signature was the only signature identified as statistically significantly associated with response to pembro in the postulated direction of negative association. Prolonged OS, but not PFS, was observed in pts with a lower Myc signature. Myc signature did not show independent predictive value beyond T cell-inflamed GEP, indicating that interferon γ-related T-cell inflammation has a more dominant impact on immunotherapy efficacy than the Myc signature and other gene sets in immune-suppressive axes. Conclusions: In this exploratory analysis, no canonical signatures showed statistical significance after adjusting for T cell-inflamed GEP. Although observed only without adjusting for T cell-inflamed GEP, Myc signature was negatively associated with response in ipilimumab-naive pts with melanoma receiving pembro monotherapy. Citation Format: Adil Daud, Matteo S. Carlino, Antoni Ribas, Ana Arance, Jean-Jacques Grob, James Larkin, Georgina V. Long, Jacob Schachter, Andrea L. Webber, Clemens Krepler, Chunsheng Zhang, Jared Lunceford, Razvan Cristescu, Qing Zhao, Junshui Ma, Caroline Robert. Evaluation of RNA-sequencing signatures with response to pembrolizumab (pembro) monotherapy in ipilimumab-naive patients (pts) with melanoma [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 2009.

A phase I study of ADXS-503 alone and in combination with pembrolizumab in subjects with metastatic squamous or non-squamous non-small cell lung cancer (NSCLC).

e21682 Background: ADXS-503 (A503) is an off-the-shelf, attenuated Listeria monocytogenes (Lm)-based immunotherapy bioengineered to elicit potent T cell responses against 22 tumor antigens commonly found in NSCLC (i.e., 11 hotspot mutations and 11 tumor-associated antigens, TAAs). Pembrolizumab (Pembro) is a programed death receptor-1 (PD-1)- blocking antibody with proven efficacy in NSCLC. A503 and Pembro have complementary mechanisms of immune activation and reversal of immune tolerance. Methods: This is a phase I study of A503 ± Pembro in patients (pts) with metastatic squamous or non-squamous NSCLC. Dose escalation with A503 alone has been tested at two dose levels (i.e., 1 and 5 x108 CFU) in Part A in pts refractory or intolerant to prior systemic therapy. In dose escalation Part B, A503 is being evaluated at the same dose levels (DLs) in combination with Pembro in pts with disease progression on Pembro. Part C will be a dose expansion cohort with A503 + Pembro as first-line treatment in the metastatic setting. A503 ± Pembro (200 mg) will be infused intravenously every 3 weeks until disease progression or limiting toxicity. Main endpoints include safety, tolerability and immune-correlative data. Results: Nine patients have been treated: 7 with A503-alone in Part A and two pts with A503+ Pembro in Part B-DL1. No pts in Part A experienced dose-limiting toxicities at the 2 DLs tested. Two Grade 3 adverse events occurred in one pt related to the infusion: hypertension and flu-like syndrome. A transient and manageable SAE (Grade 2 acute kidney injury) was possibly related to A503 alone at 5 x108 CFU. A503+ Pembro have been well tolerated in 2 pts in Part B-DL1. Four pts achieved a best overall response of stable disease, three in Part A and one in Part B. A503 alone induced immune responses in pts so far evaluated in Part A. Conclusions: ADXS-503 alone has demonstrated a manageable safety profile and immune responses in Part A. The 1x108 CFU was identified as the recommended phase II dose. Dose escalation with A503+ Pembro is ongoing and dose expansion in first line treatment is due to start shortly. Clinical trial information: NCT03847519.

A phase II study of olaparib in combination with pembrolizumab in patients with previously treated advanced solid tumors with homologous recombination repair mutation (HRRm) and/or homologous recombination repair deficiency (HRD): KEYLYNK-007.

TPS3156 Background: The anti-PD-1 antibody pembrolizumab (pembro) has improved clinical outcomes in multiple previously treated advanced solid tumors. The poly (ADP-ribose) polymerase (PARP) inhibitor olaparib (ola) has shown antitumor activity as monotherapy in previously treated advanced cancers with BRCA1/ BRCA2 mutations (BRCAm), other HRRm, and ovarian cancer with HRD phenotype. Antitumor activity of PD-(L)1 plus PARP inhibition was reportedly higher than expected with either agent alone in patients (pts) with recurrent ovarian cancer regardless of BRCAm or HRD status and in pts with BRCAm breast cancer. KEYLYNK-007 (NCT04123366) evaluates antitumor activity and safety of ola plus pembro in pts with advanced solid tumors with HRRm and/or HRD. Methods: This phase 2, nonrandomized, multicenter, open-label study plans to enroll ~300 pts aged ≥18 y with histologically/cytologically confirmed, previously treated, advanced solid tumors with HRRm and/or HRD per Lynparza HRR-HRD assay (Foundation Medicine, Inc., Cambridge, MA, USA) and ECOG PS 0-1. Pts will be grouped by biomarker status: (1) BRCAm; (2) HRRm without BRCAm; (3) HRD positive without HRRm (loss of heterozygosity score ≥16 per Lynparza HRR-HRD assay). Pts will receive ola 300 mg BID + pembro 200 mg IV Q3W (35 cycles) until PD, unacceptable AEs, intercurrent illness, investigator decision, withdrawal, or pregnancy. Tumor imaging assessment by blinded independent central review (BICR) per RECIST v1.1 or Prostate Cancer Working Group (PCWG)-modified RECIST v1.1 for prostate cancer will occur Q9W for 12 mo, then Q12W until PD, start of new anticancer treatment, withdrawal, pregnancy, or death. AEs will be monitored throughout the study and for 30 days after final dose (90 days for serious AEs) and graded by NCI CTCAE v5. The primary endpoint is ORR (RECIST v1.1 or PCWG-modified RECIST v1.1 by BICR). Secondary endpoints include DOR, PFS (RECIST v1.1 or PCWG-modified RECIST v1.1 by BICR), OS, and safety. ORR will be analyzed by the Clopper-Pearson method; and DOR, PFS, and OS by the Kaplan-Meier method. Clinical trial information: NCT04123366 .