Progression/Recurrence-Free Survival 2 in Adjuvant Melanoma

The long-term outcome of patients with stage III melanoma - that is, melanoma that has spread to nearby lymph nodes, lymphatics, or skin - who have received treatment with immune checkpoint inhibitors is of substantial interest. The article by Eggermont et al.1 published in this issue of NEJM Evidence reports 5-year outcomes from the stage III melanoma trial, KEYNOTE-054, which compared pembrolizumab (anti-programmed cell death protein 1 [PD-1]) with placebo. The data show durable recurrence-free survival (RFS) and distant metastasis-free survival (DMFS).

Autoantibodies as Predictors for Clinical Outcome and Toxicity for Immunotherapy

Peripheral blood autoantibody signatures might be useful biomarkers of immunotherapy outcome. Signatures predicting melanoma recurrence and toxicity during adjuvant immunotherapy were recently presented. Whether autoantibodies are bystanders or have a pathophysiologic role is unknown, and further efforts are needed to investigate potential mechanisms and determine causation. See related article by Johannet et al., p. 4121.

Optimal systemic therapy for high-risk resectable melanoma

Immunotherapy with immune-checkpoint inhibitors and molecularly targeted therapy with BRAF inhibitors were pioneered in the setting of advanced-stage, unresectable melanoma, where they revolutionized treatment and considerably improved patient survival. These therapeutic approaches have also been successfully transitioned into the resectable disease setting, with the regulatory approvals of ipilimumab, pembrolizumab, nivolumab, and dabrafenib plus trametinib as postoperative (adjuvant) treatments for various, overlapping groups of patients with high-risk melanoma. Moreover, these agents have shown variable promise when used in the preoperative (neoadjuvant) period. The expanding range of treatment options available for resectable high-risk melanoma, all of which come with risks as well as benefits, raises questions over selection of the optimal therapeutic strategy and agents for each individual, also considering that many patients might be cured with surgery alone. Furthermore, the use of perioperative therapy has potentially important implications for the management of patients who have disease recurrence. In this Viewpoint, we asked four expert investigators and medical or surgical oncologists who have been involved in the key studies of perioperative systemic therapies for their perspectives on the optimal management of patients with high-risk melanoma.

Predictors of Pneumonitis in Combined Thoracic Stereotactic Body Radiotherapy and Immunotherapy

PURPOSE

Thoracic stereotactic body radiotherapy (SBRT) is associated with high rates of local control but carries a risk of pneumonitis. Immunotherapy is a standard treatment for patients with metastatic disease but can also cause pneumonitis. To evaluate the feasibility and safety of thoracic SBRT with systemic immunotherapy, clinical outcomes of patients treated with immune checkpoint blockade (ICB) and SBRT on prospective trials were reviewed.

METHODS AND MATERIALS

Three consecutive phase 1 trials of combination SBRT and ICB conducted between 2016-2020 for widely metastatic solid tumors were reviewed. The protocols mandated adherence to NRG BR001/BR002 OAR constraints, resulting in <100% coverage of some target volumes. ICB was administered either sequentially (within 7 days after completion of SBRT) or concurrently (before or at the start of SBRT), depending on protocol. Endpoints included pneumonitis, dose-volume constraints, local failure, and overall survival (OS). The cumulative incidence estimator and Kaplan-Meier method were used.

RESULTS

123 patients met eligibility with 311 metastases irradiated. The most common histologies included non-small cell lung cancer (33%) and colorectal cancer (12%). Median follow up was 12 months. The overall rate of grade 3+ pneumonitis was 8.1%. 1-year local failure was 3.6%. Established dosimetric parameters were significantly associated with the development of pneumonitis (p<0.05). In most patients, the lungs were not challenged with high doses of radiation, defined as receiving ≥75% of the maximum for a given lung dose-volume constraint. Patients who were challenged were not found to have a significantly higher risk of pneumonitis.

CONCLUSIONS

In the largest series of thoracic SBRT and immunotherapy, local control was excellent with acceptable toxicity and support the conclusion that established dose-volume constraints for the lung are safe. However, these results highlight the potential value in reporting of OARs being challenged with doses approaching protocol specified limits.

Abstract LB107: Novel transcriptional signatures associated with antitumor activity in vidutolimod (vidu)-treated patients (pts) with anti-PD-1-refractory melanoma and non-small cell lung cancer (NSCLC)

Background: Vidu is a first-in-class CpG-A TLR9 agonist in a virus-like particle that activates plasmacytoid dendritic cells (pDC), thus bridging innate and adaptive immunity. Intratumoral (IT) vidu alone or in combination with intravenous (IV) anti-PD-(L)1 has shown evidence of antitumor activity in pts with anti-PD-(L)1-refractory melanoma or NSCLC. As biomarkers associated with anti-PD-(L)1 response were not predictive of vidu activity, we sought to identify novel transcriptional signatures.

Methods: RNA-Seq was performed on baseline biopsies from pts with anti-PD-(L)1-refractory melanoma (NCT02680184; RECIST v1.1 responders [R; n=20]; nonresponders [NR; n=78; 30 pts with stable disease + 48 pts with progressive disease [PD]]) or NSCLC (NCT03438318; N=11) treated with vidu ± anti-PD-(L)1. IFNg18 signature was used to characterize melanomas as non-T cell-inflamed (non-Tinfl), T cell-inflamed (Tinfl), or intermediate. Gene Set Enrichment Analysis (GSEA) using MSigDB and other signatures (&gt;19,000) was performed on non-Tinfl melanoma in R vs NR (false discovery rate [FDR] &lt;0.25). Deconvolution of immune cells was performed using TIMER2.0. Prediction models were generated using QLattice. Signatures were characterized using both publicly available bulk and single-cell (sc) RNA-Seq datasets of pDC subsets or PD-1/CTLA-4 blockade response datasets.

Results: GSEA on non-Tinfl melanoma biopsies revealed 2 gene signatures (COPII vesicle and Golgi targeting) most strongly associated with R (FDR &lt;0.16). Leading edge analysis of these signatures identified 35 common core genes (CC) that strongly differentiated RECIST 1.1 R vs PD. As independent validation, CC enrichment was also significantly associated with R in intermediate melanoma (p=0.009) and with tumor shrinkage in NSCLC (p=0.027). CC was significantly associated with R to vidu single-agent or combination treatment, but not with clinical baseline prognostic factors or IFNg18. In Tinfl melanoma, CC was not associated with R, but myeloid signatures were significantly associated with NR. A model based on CC and transcription factor ELF2 predicted R in melanoma (AUC 0.93 [95% CI 0.82-1.00]). In public datasets, CC was not associated with R to PD-1/CTLA-4 blockade, but CC was highly expressed in the type I interferon-secreting subset of pDCs and some myeloid cells. CC expression was prevalent in most tumor types and was independent of IFNg18 in TCGA.

Conclusion: In pts with anti-PD-1-refractory melanoma or NSCLC, transcriptional signatures of COPII vesicle and Golgi targeting (functionally related to TLR9 activation) were associated with antitumor activity of IT vidu ± IV anti-PD-(L)1. Ongoing bulk and sc RNA-Seq analyses may clarify the underlying biology and the signature’s potential role as a predictive biomarker for clinical response to vidu.

Citation Format: Hong Liu, Luping Zhao, Ping Zheng, Riyue Bao, Jason J. Luke, Marcelo V. Negrao, Shakoora A. Sabree, George J. Weiner, Sujatha Kumar, Dmitri Bobilev, James E. Wooldridge, Arthur M. Krieg. Novel transcriptional signatures associated with antitumor activity in vidutolimod (vidu)-treated patients (pts) with anti-PD-1-refractory melanoma and non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB107.

Abstract CT243: Phase 1 study of TAK-676 + pembrolizumab following radiation therapy in patients with advanced non-small-cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous-cell carcinoma of the head and neck (SCCHN)

Background: Radiation therapy has immune-modulating effects resulting from apoptosis of tumor cells and DNA damage. The downstream generation of cytosolic DNA activates the cyclic GMP-AMP Synthase (cGAS)-STimulator of INterferon Gene (STING) signaling axis in both tumor and nearby immune cells, leading to increased induction of type I interferon (IFN-I) and other immune stimulating molecules. TAK-676 is a novel synthetic STING agonist being investigated (+/- pembrolizumab) in an ongoing first-in-human phase 1 study (NCT04420884). TAK-676 is a potent modulator of the innate immune system and leads to downstream activation of the adaptive immune system to produce antitumor responses in preclinical studies. In contrast to intratumorally injected STING agonists, TAK-676 is optimally designed for reduced serum degradation and enhanced permeability, allowing systemic IV delivery and access to tumor sites and lymphatics. The addition of TAK-676 following radiation therapy may enhance the immune response by increasing the STING-mediated IFN-I release and further stimulate T cell-mediated antitumor immunity, particularly in combination with anti-PD-1/PD-L1 therapies. Impaired IFN signaling has been linked to checkpoint inhibitor (CPI) resistance. Preclinical studies show that addition of a STING agonist may reverse the mechanisms of resistance in tumors with prior exposure to CPIs. This phase 1 trial was designed to investigate the safety and preliminary antitumor activity of TAK-676 + pembrolizumab following radiation therapy (NCT04879849).

Methods: Patients aged ≥18 years with advanced NSCLC, TNBC, or SCCHN who have progressed on CPIs with ≥2 lesions, one of which can be targeted with radiation, are being enrolled. Patients receive 8 Gy x 3 fractions of image-guided radiation therapy followed by (after a minimum of 40 hours) IV pembrolizumab 200 mg on day 1 plus escalating doses of IV TAK-676 on days 1, 8, and 15 of a 21-day cycle. TAK-676 dose escalation is guided by the Bayesian Optimal Interval design. Patients receive TAK-676 + pembrolizumab until disease progression, intolerance, or withdrawal of consent. Once pharmacologically active dose levels of TAK-676 have been observed, paired biopsies will be collected in patients with a safely accessible lesion outside the radiation field at screening and between days 15 and 21 of cycle 1. The primary objective is to determine the safety and tolerability of TAK-676 + pembrolizumab following radiation therapy; secondary objectives are to determine the recommended phase 2 dose of TAK-676 + pembrolizumab following radiation therapy, and to assess preliminary antitumor activity both locally (in the radiation field) and systemically (non-radiated lesions). As of January 2022, nearly 10% of the planned patients have been enrolled.

Citation Format: Benjamin Cooper, Steven J. Chmura, Jason J. Luke, Stephen L. Shiao, Reva K. Basho, Wade T. Iams, David B. Page, Cong Li, Richard C. Gregory, Michael H. Shaw, Kristin H. Horn, John P. Gibbs, Vicky A. Appleman, Allison J. Berger, Adnan O. Abu-Yousif, Neil B. Lineberry, Kate F. Stumpo, Aymen Elfiky, Naamit K. Gerber. Phase 1 study of TAK-676 + pembrolizumab following radiation therapy in patients with advanced non-small-cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous-cell carcinoma of the head and neck (SCCHN) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT243.

Distant metastasis-free survival with pembrolizumab versus placebo as adjuvant therapy in stage IIB or IIC melanoma: The phase 3 KEYNOTE-716 study

LBA9500

Background: In previous analyses of the phase 3, double-blind KEYNOTE-716 study, adjuvant pembrolizumab (pembro) significantly improved recurrence-free survival compared with placebo in patients (pts) with resected AJCC-8 stage IIB or IIC melanoma. We present new data from the analysis of distant metastasis-free survival (DMFS), and recurrence-free survival (RFS) with longer follow up. Methods: A total of 976 pts aged ≥12 years with complete resection of cutaneous stage IIB or IIC melanoma and negative sentinel lymph node biopsy were randomized 1:1 to pembro 200 mg (2 mg/kg for pediatric pts) or placebo Q3W for 17 cycles (approximately 1 year) in Part 1 of the study. Randomization was stratified by T category 3b, 4a, 4b (adults) with a separate stratum for pediatric pts. Treatment continued until disease recurrence or unacceptable toxicity. Pts who received placebo in Part 1, or who did not experience disease progression within 6 months of completing Part 1 were eligible for additional cycles of pembro Q3W at recurrence (Part 2). The primary endpoint was RFS per investigator. DMFS by investigator is a secondary endpoint. The data cut-off date for this interim analysis was Jan 4th, 2022. Results: At median follow-up of 26.9 mo (range, 4.6-39.2), adjuvant pembro significantly improved DMFS (HR 0.64, 95% CI, 0.47-0.88; P=0.0029; median not reached [NR] for both) vs placebo. The 24-mo DMFS rate was 88.1% vs 82.2%. There was consistent reduction in the risk of recurrence with pembro vs placebo (HR 0.64, 95% CI, 0.50-0.84) with further follow-up. The 24-mo RFS rate was 81.2% vs 72.8%. Grade ≥ 3 any-cause AEs occurred in 137 (28.4%) vs 97 (20.0%) pts in the pembro vs placebo arms. Grade ≥ 3 drug-related AEs occurred in 83 (17.2%) vs 24 (4.9%) pts. One pt in the pembro arm and 5 pts in the placebo arm died due to an any-cause AE. No deaths were drug-related. Immune-mediated AEs occurred in 182 (37.7%) vs 45 (9.3%) pts, most commonly hypothyroidism (17.2% vs 3.7%). Conclusions: Adjuvant pembrolizumab vs placebo for resected stage IIB and IIC melanoma significantly improved DMFS, with continued reduction in the risk of recurrence, and a favorable benefit-risk profile. Clinical trial information: NCT03553836.

Phase I Study of Safety, Tolerability, and Efficacy of Tebentafusp Using a Step-Up Dosing Regimen and Expansion in Patients With Metastatic Uveal Melanoma

PURPOSE

This phase I study aimed to define the recommended phase II dose (RP2D) of tebentafusp, a first-in-class T-cell receptor/anti-CD3 bispecific protein, using a three-week step-up dosing regimen, and to assess its safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity in patients with metastatic uveal melanoma (mUM).

METHODS

In this open-label, international, phase I/II study, HLA-A*02 or HLA-A*02:01+ patients with mUM received tebentafusp 20 μg once in week 1 and 30 μg once in week 2. Dose escalation (starting at 54 μg) began at week 3 in a standard 3 + 3 design to define RP2D. Expansion-phase patients were treated at the RP2D (20-30-68 μg). Blood and tumor samples were collected for pharmacokinetics/pharmacodynamics assessment, and treatment efficacy was evaluated for all patients with baseline efficacy data as of December 2017.

RESULTS

Between March 2016 and December 2017, 42 eligible patients who failed a median of two previous treatments were enrolled: 19 in the dose escalation cohort and 23 in an initial dose expansion cohort. Of the dose levels investigated, 68 μg was identified as the RP2D. Most frequent treatment-emergent adverse events regardless of attribution were pyrexia (91%), rash (83%), pruritus (83%), nausea (74%), fatigue (71%), and chills (69%). Toxicity attenuated following the first three doses. The overall response rate was 11.9% (95% CI, 4.0 to 25.6). With a median follow-up of 32.4 months, median overall survival was 25.5 months (range, 0.89-31.1 months) and 1-year overall survival rate was 67%. Treatment was associated with increased tumor T-cell infiltration and transient increases in serum inflammatory mediators.

CONCLUSION

Using a step-up dosing regimen of tebentafusp allowed a 36% increase in the RP2D compared with weekly fixed dosing, with a manageable side-effect profile and a signal of efficacy in mUM.

Phase 1 dose escalation study of DSP107, a first-in-class CD47 and 4-1BB targeting multifunctional immune-recruitment protein, in patients with advanced solid tumors

2647

Background: DSP107 is a bi-functional, trimeric, fusion protein composed of sequences from the extracellular domain of SIRPα and 4-1BBL. The SIRPα arm targets CD47 overexpressed on tumor cells, blocking the “don’t eat me” checkpoint and triggering tumor cell phagocytosis. The trimeric 4-1BBL arm, once cross-presented and immobilized by SIRPα binding to CD47, interacts with 4-1BB expressed on activated immune cells, mainly T- and NK cells in the tumor microenvironment, and stimulates their proliferation and activation. Thereby, DSP107 triggers both an innate and an adaptive immune response. Here we describe data from the completed DSP107 monotherapy dose escalation portion of study NCT04440735. Methods: Adult patients with advanced solid tumors were treated with weekly intravenous DSP107 infusions (0.01 - 10 mg/kg) during 3-week treatment cycles. An accelerated dose escalation in single patient cohorts (dose levels 1-3) was followed by a standard 3 + 3 design. The primary objective was to determine safety, tolerability and pharmacokinetic (PK) parameters. Paired biopsies were obtained from 8 patients (screening, after cycle 2). Restaging imaging was performed every two months and evaluated by RECIST criteria. Results: In 23 patients, DSP107 demonstrated no treatment related hematologic or hepatic adverse events (AEs) and no dose limiting toxicities. Grade 1-2 treatment related AEs were observed in 70% of patients (16/23). The most frequent AEs included infusion related reaction (IRR; 26%), diarrhea (17%), fatigue (17%), nausea (13%) and constipation (9%). IRRs were managed during subsequent infusions by reducing the infusion rate and administering IV fluids. No significant systemic cytokine release was measured at any dose level using a 10-plex, pro-inflammatory panel. PK analysis revealed 100% CD47 receptor engagement on peripheral T and NK cells at doses of 3 mg/kg and above. DSP107 did not bind CD47 on red blood cells at any dose. Preliminary histologic assessment of paired biopsies by an independent, blinded pathologist demonstrated increased tumor necrosis compared to screening in 3 out of 4 patients associated with immune cell infiltration. Immuno-profiling of tumor by immunofluorescence is on-going. Stable disease as best response was observed in 11/22 patients with treatment duration up to 26 weeks. Conclusions: DSP107 is a novel, CD47 and 4-1BB targeting fusion protein with a differentiated safety, binding and pharmacodynamic profile compared to other CD47 and 4-1BB targeting agents. Clinical trial information: NCT04440735.

TAK-676 in combination with pembrolizumab after radiation therapy in patients (pts) with advanced non–small cell lung cancer (NSCLC), triple-negative breast cancer (TNBC), or squamous-cell carcinoma of the head and neck (SCCHN): Phase 1 study design

TPS2698

Background: The cyclic GMP-AMP Synthase (cGAS)–STimulator of INterferon Genes (STING) pathway is an important modulator of the innate immune system via induction of type I interferon (IFN-I). Cytosolic DNA generated as a result of tumor cell death following radiation therapy has been demonstrated to activate the cGAS-STING signaling axis resulting in antitumor immunogenicity. TAK-676 is a novel, synthetic STING agonist and it has been shown in preclinical studies to potently modulate the innate immune system and subsequently activate the adaptive immune system to produce antitumor responses. TAK-676 is designed for prolonged half-life in serum and enhanced tissue permeability compared with other STING agonists designed for intratumoral injection, allowing for systemic IV delivery with access to tumor sites and lymphatic tissue. IFN signaling impairment has been linked to checkpoint inhibitor (CPI) resistance in tumors. Treatment with TAK-676 after radiation therapy has the potential to stimulate T cell-mediated antitumor immunity via STING-mediated IFN-I release, particularly when used with anti-PD-1/PD-L1 therapies. Preclinical data support the addition of STING agonists to reverse resistance in tumors with prior exposure to CPIs. TAK-676 is being investigated (+/- pembrolizumab) in an ongoing first-in-human phase 1 study (NCT04420884). Here, we describe another phase 1 trial to investigate the safety and preliminary antitumor activity of TAK-676 plus pembrolizumab following radiation therapy in pts with advanced or metastatic NSCLC, TNBC, or SCCHN (NCT04879849). Methods: Adult pts with progressive disease (PD) following CPI treatment and who have ≥2 lesions, 1 of which can be targeted with radiation, are being enrolled. Pts receive 8 Gy x 3 fractions of image-guided radiation followed (after ≥40 hours) by IV pembrolizumab 200 mg on day 1 plus escalating doses of IV TAK-676 on days 1, 8, and 15 of a 21-day cycle. TAK-676 dose escalation is guided by the Bayesian optimal interval design. Pts receive TAK-676 plus pembrolizumab until PD, intolerance to treatment, or withdrawal. Pts enrolled at TAK-676 dose levels shown to have pharmacodynamic activity, and who have a safely accessible lesion outside the radiation field, will have paired biopsies collected at screening and between days 15 and 21 of cycle 1. The primary objective is to determine the safety and tolerability of TAK-676 plus pembrolizumab following radiation therapy; secondary objectives are to establish the recommended phase 2 dose of TAK-676 plus pembrolizumab following radiation therapy, and to assess preliminary antitumor activity both locally (within the radiation field) and systemically (non-radiated lesions). As of February 2022, we have enrolled ̃10% of the planned pts. Clinical trial information: NCT04879849.

Phase 1a/b open-label study of IK-175, an oral AHR inhibitor, alone and in combination with nivolumab in patients with locally advanced or metastatic solid tumors and urothelial carcinoma

TPS3169

Background: Aryl Hydrocarbon Receptor (AHR) is a ligand-activated transcription factor that regulates the activity of multiple innate and adaptive immune cells. Kynurenine, generated from tryptophan by IDO1 and TDO2, is a ligand that binds AHR and leads to a net immunosuppressive tumor microenvironment, making AHR an attractive therapeutic target in multiple cancer types. IK-175 is a selective, small molecule inhibitor of AHR being developed as an oral agent. In preclinical mouse tumor models, IK-175 demonstrates antitumor activity as a single agent or in combination with checkpoint inhibitors. AHR immunohistochemistry (IHC) tumor microarray analysis across 15 different tumor types revealed that bladder cancer has the highest level of AHR protein expression and nuclear localization indicative of ligand-bound and active AHR signaling. Therefore, nuclear AHR in urothelial carcinoma tumors is being investigated for potential predictive clinical benefit with IK-175. Methods: This is a first-in-human, phase 1a/b, open-label, multicenter, dose-escalation and expansion study of IK-175 as a single agent and in combination with nivolumab. The primary objectives are to determine the maximum tolerated dose (MTD) and/or maximum administered dose (MAD), identify the recommended phase 2 dose (RP2D), and evaluate the safety and tolerability of IK-175 alone and in combination with nivolumab. Secondary objectives are to evaluate the pharmacokinetics (PK) of IK-175, evaluate pharmacodynamic (PD) immune effects, and assess preliminary antitumor activity. Key exploratory objectives are to evaluate the PD effects on peripheral immune cells and target gene expression, to assess candidate baseline biomarkers, and correlative analyses of tumor AHR nuclear localization with clinical response. The study is exploring tumor AHR nuclear localization by IHC as a predictive biomarker in patients with urothelial carcinoma. A minimum of 10 patients with a positive AHR nuclear localization test (cutoff for positive AHR is 65% tumor cells positive for 2+/3+ nuclear AHR by a validated IHC assay) will be enrolled in the combination arm. IK-175 is administered daily in 21 or 28 day-cycles as a single agent, and in combination with nivolumab (480 mg q4w on Day 1 of every cycle), in adult patients with advanced solid tumors (dose escalation) and urothelial carcinoma (dose expansion). Key eligibility criteria include patients with histologically confirmed solid tumors (including urothelial carcinoma) who have locally recurrent or metastatic disease that have progressed on or following all standard of care therapies deemed appropriate by the treating physician including prior checkpoint inhibitors. Estimated enrollment is 93 patients; the study began in January 2020 and is ongoing. Clinical trial information: NCT04200963.

Nivolumab (NIVO) + tacrolimus (TACRO) + prednisone (PRED) +/- ipilimumab (IPI) for kidney transplant recipients (KTR) with advanced cutaneous cancers

9507

Background: Cancer is a leading cause of death among KTR, but these patients (pts) have been excluded from trials of immune checkpoint inhibitors due to immunosuppression and risk of allograft loss. We report findings from the first prospective clinical trial of NIVO + TACRO + PRED +/- IPI in KTR with selected advanced cutaneous cancers. Methods: The primary composite endpoint was lack of tumor progression per RECIST v1.1 without allograft loss at 16 weeks (W) on NIVO. Adult KTR with advanced melanoma, basal, cutaneous squamous, or Merkel cell carcinoma (MEL, BCC, CSCC, MCC), for whom non-immune therapies were insufficient were eligible. Immunosuppression was standardized to low-dose TACRO (goal trough 2-5 ng/mL) + PRED 5mg daily; pts then received NIVO 480mg IV q4W. Pts with progressive disease (PD) could receive NIVO 3mg/kg + IPI 1mg/kg IV q3W x 4 followed by NIVO 480mg IV q4W. Donor-derived cell-free DNA (dd-cfDNA) levels were measured q2W as a potential predictor of allograft rejection. Results: From 11/2019 - 4/2021, of 12 pts enrolled, 8 pts with CSCC, MCC or MEL were evaluable for response (Table). All pts experienced PD on NIVO; treatment-related allograft loss (TRAL) occurred in 1 pt. 6 pts then received IPI + NIVO. Responses: 2 (33%) with marked tumor regression at 6W and eventual complete response (CR; 1 with TRAL), and 4 (67%) with PD (1 with TRAL). 7/8 pre-NIVO tumor biopsies contained a paucity of infiltrating immune cells. Only 2/5 on-NIVO biopsies demonstrated moderate immune infiltrates; both of these pts later developed a CR to IPI + NIVO. Rejecting allografts contained dense immune responses (plasma cells, CD4+ & CD8+ lymphocytes, PD-1+ lymphocytes, macrophages, PD-L1+ glomerular endothelium, and focal PD-1 & PD-L1 positivity in renal tubules). In 2/3 pts with TRAL, elevations in dd-cfDNA levels occurred 10 and 15 days earlier than increases in weekly serum creatinine levels. TRAL #3 occurred after discontinuation of study therapy (including TACRO) and dd-cfDNA monitoring. Conclusions: In KTR receiving low-dose TACRO + PRED, NIVO augments tumor immune cell infiltration in some pts but is insufficient to mediate tumor regression. Adding IPI can enhance anti-tumor immunity and mediate tumor regression. TACRO + PRED was insufficient to prevent allograft rejection after PD-1 +/- CTLA-4 blockade in 2/8 pts. In pts with TRAL, increased dd-cfDNA levels preceded increased serum creatinine. Based on these findings, we are modifying the trial therapy regimen to augment anti-tumor immunity and preserve allograft function. Clinical trial information: NCT03816332. [Table: see text]

Analysis of the effect of systemic corticosteroids on survival from tebentafusp in a phase 3 trial of metastatic uveal melanoma

9584

Background: All immune therapies that rapidly activate T cells, including T cell engagers, can induce cytokine release syndrome (CRS). Tebentafusp (tebe), a T cell receptor bispecific (gp100 x CD3) can also induce skin adverse events (AEs), due to gp100+ cutaneous melanocytes. CRS and skin AEs may require management with short term corticosteroids, which may also be used as premedication for subsequent tebe doses. Here we report the first analysis of systemic corticosteroid use and correlation with efficacy from a Phase (Ph) 3 trial for any T cell engager. Methods: Post hoc analyses were performed on the tebe arm of the Ph3 [NCT03070392] study in previously untreated HLA-A*02:01+ metastatic uveal melanoma (mUM) (N = 245). Due to the low rate of severe AEs in Ph1 trials, prophylactic corticosteroids were not mandated. The association between overall survival (OS) and corticosteroid use (new start within 30 days of first tebe dose) was investigated using landmark analyses in the safety population. Multivariate analyses were adjusted for key patient characteristics and AEs of special interest: CRS, rash, and liver function test (LFT) elevation. Steroid type (hydrocortisone vs. others) and treatment duration (1 vs. > 1 day) were also investigated. Results: In the Ph3 trial, 64/245 (26%) patients received new systemic corticosteroid within 30 days after the first dose of tebe, mostly for treatment of AEs (56/64, 88%) or pre-medication due to previous AE (14/64, 22%). 25 of the 64 patients received corticosteroids only for a single day. The most frequent AEs (≥15%) were rash (18/64, 28%), CRS (15/64, 23%), and hypotension (12/64, 19%). In a logistic regression model, elevated baseline LDH, the dominant prognostic marker, was most strongly associated with use of corticosteroids (p = 0.01). In the multivariate analysis, corticosteroids were not associated with any significant OS difference (HR 1.41, 95% CI 0.83-2.4, p = 0.2) and this effect did not differ in patients with or without CRS, rash or LFT elevation (all interaction tests p > 0.2). There was no difference in OS according to corticosteroid type or whether administered for 1 vs > 1 day. Conclusions: This is the first analysis from a phase 3 trial of the impact of systemic corticosteroids on survival for a T cell engaging cancer therapy. The vast majority of tebe-treated patients (84%) either did not require corticosteroids (74%) or only received them on a single day (10%). The most frequent reason for corticosteroid use was an emergent AE, including CRS and rash. Corticosteroid use following the pre-specified AE guidelines was not associated with any significant impact on OS. Clinical trial information: NCT03070392.

An open-label, multicenter, phase 1b/2 study of RP1, a first-in-class, enhanced potency oncolytic virus in solid organ transplant recipients with advanced cutaneous malignancies (ARTACUS)

TPS9597

Background: RP1 is an oncolytic virus (HSV-1) that expresses a fusogenic glycoprotein (GALV-GP R-) and granulocyte macrophage colony stimulating factor (GM-CSF). In preclinical studies, RP1 induced immunogenic tumor cell death and provided potent systemic anti-tumor activity. Clinical data in combination with nivolumab has demonstrated a high rate of deep and durable response in patients with advanced skin cancer. Solid organ transplantation (SOT) is an important lifesaving procedure for patients with a wide range of end-organ diseases, but requires patients (pts) to undergo lifelong immunosuppression to prevent allograft rejection, and skin cancers (SCs) – including cutaneous squamous cell carcinoma (CSCC) – are common post-transplant malignancies. SC in SOT pts is generally managed with surgical resection, radiation therapy, and chemotherapy or targeted therapy. The use of immune checkpoint inhibitors in SOT recipients has improved outcomes but is associated with a high risk of allograft rejection. Thus, there is a high unmet need for a safe and effective treatment that also protects pts from allograft rejection. The objective of this study is to assess the safety and efficacy of single-agent RP1 in SOT patients with SCs, with a focus on CSCC. Methods: This study will enroll up to 65 evaluable SOT pts with locally advanced or metastatic SCs. The study has two parts. In Part A, pts will receive an initial dose of 1 x 106 plaque-forming units (PFU) of RP1. Two weeks later they will receive 1 x 107 PFU of RP1 and continue every two weeks until pre-specified study endpoints are met. In Part B, after determining the safety and tolerability in the initial cohort with kidney and liver transplants, the study may also enroll heart and lung transplant recipients. RP1 will be administered by intra-tumoral injection, utilizing image guidance as clinically appropriate. Key inclusion criteria are pts with confirmed recurrent, locally advanced or metastatic CSCC and up to 10 pts with non-CSCC SC, stable allograft function and ECOG performance status of ≤1. Pts with prior systemic anti-cancer treatment are allowed. Key exclusion criteria are prior treatment with an oncolytic therapy, active herpetic infections or prior complications of HSV-1 infection and a history of organ graft rejection within 12 months. The primary objective of the trial is to assess efficacy determined by objective response rate and safety of single agent RP1. Additional secondary endpoints include duration of response, complete response rate, disease control rate, progression-free survival and overall survival. Clinical trial information: NCT04349436.

Phase 1 trial of TIM-3 inhibitor cobolimab monotherapy and in combination with PD-1 inhibitors nivolumab or dostarlimab (AMBER)

2504

Background: TIM-3 expressed on tumor-infiltrating T cells is associated with T-cell suppression. AMBER (NCT02817633) is evaluating cobolimab (TSR-022/GSK4069889) monotherapy and with PD-1 inhibitors in advanced solid tumors. Methods: Multi-center, open-label study conducted with the following escalation arm (Parts 1A–C primary analysis reported here): (1A) cobolimab (IV Q2W) monotherapy at 7 doses (6 weight-based [0.03–10 mg/kg] and 1 flat [1200 mg] dose); (1B) cobolimab (1 mg/kg) + nivolumab (3 mg/kg IV Q2W); and (1C) cobolimab (100, 300, or 900 mg) + dostarlimab (500 mg IV Q3W). Primary endpoints were safety, tolerability, and recommended phase 2 dose (RP2D, monotherapy and combination). Results: 104 patients (pts) were included: 1A (n=46), 1B (n=7), or 1C (n=55); 4 pts from 1A crossed over to 1C (included in 1A and 1C safety and efficacy analyses). Most common cancers were non-small cell lung cancer (NSCLC) and melanoma (1A), NSCLC (1B), and NSCLC, skin, and peritoneal mesothelioma (1C). In 1A, 30.4% had ≥5 lines (L) of prior therapy; 42.9% had 3L in 1B; 33.3% had 2L in 1C. Treatment-related treatment-emergent adverse events (TR-TEAE) occurred in 67.4% (1A), 85.7% (1B), and 67.3% (1C); most commonly in 1A (n≥4) fatigue (13.0%) and nausea (8.7%); 1B (n≥3) diarrhea (57.1%) and nausea and vomiting (42.9% each); and 1C (n≥8) fatigue (20.0%) and rash (14.5%). Grade (Gr)≥3 TR-TEAEs occurred in 4.3% (1A), 28.6% (1B), and 14.5% (1C). There were no Gr5 TR-TEAEs or TR-TEAEs leading to dose delay. Serious TR-TEAEs occurred in 2.2% (1A), 0% (1B), and 12.7% (1C). TR-TEAEs led to discontinuation in 2.2% (1A), 28.6% (1B), and 9.0% (1C). Dose limiting toxicities (DLTs) occurred in 3.0% (1/33) in 1A (Gr3 lipase increased [10 mg/kg]); 40.0% (2/5) in 1B (Gr3 diarrhea and ALT and AST elevation); and 0% in 1C. Cobolimab serum exposure increased in a dose proportional manner at the therapeutic dose range. Preliminary mean terminal phase t1/2 ranged from 2.5–5.8 days for 0.03–0.3 mg/kg and 6.9–10.2 days for 1–10 mg/kg doses (1A), 6.9 days for 1B, and 9.5–12.3 days for 1C. Conclusions: Cobolimab + dostarlimab was well tolerated and showed preliminary anti-tumor activity, warranting further investigation of the RP2D + docetaxel in a randomized, phase 2 study. Funding: GSK (213348). Clinical trial information: NCT02817633. [Table: see text]

Health-related quality of life (HRQoL) with pembrolizumab (pembro) in resected high-risk stage II melanoma in the phase 3 KEYNOTE-716 study

9581

Background: Adjuvant pembro improved RFS vs placebo (HR, 0.61; 95% CI, 0.45-0.82) and had manageable safety in patients (pts) with resected high-risk stage II melanoma at second interim analysis of KEYNOTE-716 (NCT03553836). HRQoL results are presented. Methods: Pts aged ≥12 y with resected stage IIB/C melanoma were randomized 1:1 to adjuvant pembro 200 mg (2 mg/kg for pts ≥12 and < 18 y) Q3W or placebo for ≤17 cycles. Change from baseline in HRQoL was an exploratory end point. EORTC QLQ-C30 and EQ-5D-5L were administered at baseline; cycles 5, 9, 13, and 17 in y 1; every 12 wk in y 2; and every 6 mo in y 3. The HRQoL population included all pts who received ≥1 dose of study treatment and had ≥1 HRQoL assessment available. Least-squares mean (LSM) change from baseline to wk 48 in EORTC QLQ-C30 global health status (GHS)/quality of life (QoL) and physical functioning (PF) and EQ-5D-5L visual analog scale (VAS) were calculated using a constrained longitudinal data analysis model; HRQoL score was the response variable with treatment by time interaction and T stage at baseline as covariates. Empirical mean change from baseline in QLQ-C30 GHS/QoL and PF scores over time was evaluated. A ≥10-point improvement or decline in QLQ-C30 scores was considered clinically meaningful. Data cutoff was June 21, 2021. Results: Of 976 pts enrolled, 969 were included in the HRQoL population (483 pembro; 486 placebo). Median follow-up in the ITT population was 20.5 mo (range, 4.6-32.7). At wk 48, compliance (adherence) for EORTC QLQ-C30 was 83.4% for pembro and 89.3% for placebo and completion was 70.6% and 75.7%, respectively. At wk 48, compliance for EQ-5D-5L was 84.1% for pembro and 90.0% for placebo and completion was 71.2% and 76.3%, respectively. QLQ-C30 GHS/QoL and PF and EQ-5D-5L VAS scores were similar between arms at baseline. LSM change from baseline to wk 48 in QLQ-C30 GHS/QoL score was −4.49 (95% CI, −6.19 to −2.79) for pembro and −0.82 (95% CI, −2.47 to 0.83) for placebo (LSM difference: −3.67; 95% CI, −5.91 to −1.44). LSM change from baseline to wk 48 in QLQ-C30 PF score was −3.27 (95% CI, −4.61 to −1.92) for pembro and −1.77 (95% CI, −3.07 to −0.46) for placebo (LSM difference: −1.50; 95% CI, −3.33 to 0.32). LSM change from baseline to wk 48 in EQ-5D-5L VAS score was −2.19 (95% CI, −3.52 to −0.85) for pembro and −0.25 (95% CI, −1.54 to 1.04) for placebo (LSM difference: −1.94; 95% CI, −3.72 to −0.16). LSM change from baseline to wk 48 in other QLQ-C30 functioning and symptom scales was similar in both arms. Empirical mean change from baseline in QLQ-C30 GHS/QoL and PF was similar over 96 wk in both arms. Conclusions: No clinically meaningful decreases in EORTC QLQ-C30 or EQ-5D-5L VAS scores were observed for adjuvant pembro or placebo. These results, along with improved RFS and manageable safety, support the use of adjuvant pembro in resected high-risk stage II melanoma. Clinical trial information: NCT03553836.

Phase II study of nivolumab (nivo) with relatlimab (rela) in patients (pts) with first-line advanced melanoma: Early on-treatment major pathologic response on biopsy

9514

Background: A phase II study of nivo and rela was designed to evaluate the antitumor activity and mechanism of this combination and components for first-line treatment of pts with advanced melanoma. Pts received lead-in treatment with 1 cycle of nivo (480mg IV q4wk), rela (160mg IV q4wk), or nivo-rela followed by combination therapy. We assessed the effect of each lead-in treatment on immune-related pathological response (irPR) at 4-wk biopsy to develop early biomarkers of antitumor response. Methods: Core biopsy of an index lesion was performed at baseline and after 4 wk on-treatment. Immune characteristics of pathological response were assessed on H&E sections, including presence of tumor-infiltrating lymphocytes (TIL), neovascularization, proliferative fibrosis, plasma cells, and lymphoid aggregates. irPR score was calculated as described by Stein JE et al Ann Oncol 2019, from 0 (no irPR features) to 3 (major pathologic response on biopsy [MPRbx], ≤10% residual viable tumor). We assessed the association between irPR and radiological response (RECIST v1.1) at 4-wk evaluations. Results: The current cohort includes 22 pts, median age = 67, male = 13. Pts were randomized to nivo = 7, rela = 7, and nivo-rela = 8 lead-in groups. Two pts had no irPR evaluation due to early progression and unscorable tumor. Among 20 evaluable pts, proliferative fibrosis, neovascularization, plasma cells, brisk TIL, and lymphoid aggregates were identified in 50%, 35%, 26.3%, 25%, and 5% of cases, respectively. Lead-in nivo (n = 2/6), rela (n = 0/6), and nivo-rela (n = 3/8) resulted in irPR = 3 in 25% of pts. Radiological response was identified as partial response (PR) = 1/22 (4.5%), stable disease (SD) = 12/22 (54.5%), and progressive disease (PD) = 9/22 (41%). Among pts with PD, 44% received rela-, 33% nivo-, and 22% nivo-rela- lead-in. Pts with irPR score = 3 had radiological PR = 1, SD = 3, and PD = 1 at 4wks. No association was found between MPRbx and radiological response at 4 wks. Conclusions: Four-wk MPRbx may serve as an early biomarker of treatment response in advanced melanoma. Lead-in treatment resulted in MPRbx of 25% and was greatest with nivo-rela lead-in. Correlations between 4 wk MPRbx and later radiological responses, survival and other endpoints will be made at completion of trial accrual. Clinical trial information: NCT03743766. [Table: see text]

The "Great Debate" at Melanoma Bridge 2021, December 2nd-4th, 2021

The Great Debate session at the 2021 Melanoma Bridge virtual congress (December 2-4) featured counterpoint views from experts on seven important issues in melanoma. The debates considered the use of adoptive cell therapy versus use of bispecific antibodies, mitogen-activated protein kinase (MAPK) inhibitors versus immunotherapy in the adjuvant setting, whether the use of corticosteroids for the management of side effects have an impact on outcomes, the choice of programmed death (PD)-1 combination therapy with cytotoxic T-lymphocyte-associated antigen (CTLA)-4 or lymphocyte-activation gene (LAG)-3, whether radiation is needed for brain metastases, when lymphadenectomy should be integrated into the treatment plan and then the last debate, telemedicine versus face-to-face. As with previous Bridge congresses, the debates were assigned by meeting Chairs and positions taken by experts during the debates may not have necessarily reflected their respective personal view. Audiences voted both before and after each debate.

Phase IB Study of GITR Agonist Antibody TRX518 Singly and in Combination with Gemcitabine, Pembrolizumab or Nivolumab in Patients with Advanced Solid Tumors

Purpose: TRX518 is a monoclonal antibody engaging the glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR). This open-label, phase I study (TRX518-003) evaluated the safety and efficacy of repeated dose TRX518 monotherapy and combination with gemcitabine, pembrolizumab or nivolumab in advanced solid tumors. Experimental Design: TRX518 monotherapy was dose-escalated (Part A) and expanded (Part B) up to 4 mg/kg load, 1 mg/kg Q3W. Parts C-E included dose-escalation (2mg/kg and 4 mg/kg loading followed by 1mg/kg) and dose-expansion (4mg/kg load) phases with gemcitabine (Part C), pembrolizumab (Part D) or nivolumab (Part E). Primary endpoints included incidence of dose-limiting toxicities (DLTs), serious adverse events (SAEs), and pharmacokinetics. Secondary endpoints were efficacy and pharmacodynamics. Results:109 patients received TRX518: 43 (Parts A+B), 30 (Part C), 26 (Part D), and 10 (Part E) respectively. 67% of patients in Parts D+E had received prior anti-PD(L)1 or anti-CTLA-4. No DLTs, treatment-related SAEs and/or G4/5 AEs were observed with TRX518 monotherapy. In Parts C-E, no DLTs were observed, although TRX518-related SAEs were reported in 3.3% (Part C) and 10.0% (Part E) respectively. Objective response rate was 3.2%, 3.8%, 4% and 12.5% in Parts A+B, C, D and E respectively. TRX518 affected peripheral and intratumoral regulatory T cells (Tregs) with different kinetics depending on the combination regimen. Responses with TRX518 monotherapy+anti-PD1 combination were associated with intratumoral Treg reductions and CD8 increases and activation after treatment. Conclusions:TRX518 showed an acceptable safety profile with pharmacodynamic activity. Repeated dose TRX518 monotherapy and in combination resulted in limited clinical responses associated with immune activation.

Pembrolizumab versus placebo as adjuvant therapy in completely resected stage IIB or IIC melanoma (KEYNOTE-716): a randomised, double-blind, phase 3 trial

BACKGROUND

Pembrolizumab prolongs progression-free and overall survival among patients with advanced melanoma and recurrence-free survival in resected stage III disease. KEYNOTE-716 assessed pembrolizumab as adjuvant therapy in patients with completely resected, high-risk, stage II melanoma. We report results from the planned first and second interim analyses for recurrence-free survival.

METHODS

In this double-blind, randomised, placebo-controlled phase 3 study, involving 160 academic medical centres and hospitals in 16 countries (Australia, Belgium, Brazil, Canada, Chile, France, Germany, Israel, Italy, Japan, Poland, South Africa, Spain, Switzerland, the UK, and the USA), patients aged 12 years or older with newly diagnosed, completely resected stage IIB or IIC melanoma (TNM stage T3b or T4 with a negative sentinel lymph node biopsy) were recruited. Eligible patients were randomly assigned (1:1), in blocks of four and stratified by T-category (3b, 4a, and 4b) and paediatric status (age 12-17 years vs ≥18 years), using an interactive response technology system to intravenous pembrolizumab 200 mg (2 mg/kg in paediatric patients) or placebo every 3 weeks for 17 cycles or until disease recurrence or unacceptable toxicity. All patients, clinical investigators, and analysts were masked to treatment assignment. The primary endpoint was investigator-assessed recurrence-free survival (defined as time from randomisation to recurrence or death) in the intention-to-treat (ITT) population (ie, all patients randomly assigned to treatment). The primary endpoint was met if recurrence-free survival was significantly improved for pembrolizumab versus placebo at either the first interim analysis (after approximately 128 patients had events) or second interim analysis (after 179 patients had events) under multiplicity control. Safety was assessed in all patients randomly assigned to treatment who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03553836, and is closed to accrual.

FINDINGS

Between Sept 23, 2018, and Nov 4, 2020, 1182 patients were screened, of whom 976 were randomly assigned to pembrolizumab (n=487) or placebo (n=489; ITT population). The median age was 61 years (IQR 52-69) and 387 (40%) patients were female and 589 (60%) were male. 874 (90%) of 976 patients were White and 799 (82%) were not Hispanic or Latino. 483 (99%) of 487 patients in the pembrolizumab group and 486 (99%) of 489 in the placebo group received assigned treatment. At the first interim analysis (data cutoff on Dec 4, 2020; median follow-up of 14·4 months [IQR 10·2-18·7] in the pembrolizumab group and 14·3 months [10·1-18·7] in the placebo group), 54 (11%) of 487 patients in the pembrolizumab group and 82 (17%) of 489 in the placebo group had a first recurrence of disease or died (hazard ratio [HR] 0·65 [95% CI 0·46-0·92]; p=0·0066). At the second interim analysis (data cutoff on June 21, 2021; median follow-up of 20·9 months [16·7-25·3] in the pembrolizumab group and 20·9 months [16·6-25·3] in the placebo group), 72 (15%) patients in the pembrolizumab group and 115 (24%) in the placebo group had a first recurrence or died (HR 0·61 [95% CI 0·45-0·82]). Median recurrence-free survival was not reached in either group at either assessment timepoint. At the first interim analysis, grade 3-4 treatment-related adverse events occurred in 78 (16%) of 483 patients in the pembrolizumab groups versus 21 (4%) of 486 in the placebo group. At the first interim analysis, four patients died from an adverse event, all in the placebo group (one each due to pneumonia, COVID-19-related pneumonia, suicide, and recurrent cancer), and at the second interim analysis, one additional patient, who was in the pembrolizumab group, died from an adverse event (COVID-19-related pneumonia). No deaths due to study treatment occurred.

INTERPRETATION

Pembrolizumab as adjuvant therapy for up to approximately 1 year for stage IIB or IIC melanoma resulted in a significant reduction in the risk of disease recurrence or death versus placebo, with a manageable safety profile.

FUNDING

Merck Sharp & Dohme, a subsidiary of Merck & Co, Kenilworth, NJ, USA.

Exploring the safety, effect on the tumor microenvironment, and efficacy of itacitinib in combination with epacadostat or parsaclisib in advanced solid tumors: a phase I study

BACKGROUND

This phase I multicenter study was designed to evaluate the safety, tolerability, efficacy, and translational effects on the tumor microenvironment of itacitinib (Janus-associated kinase 1 (JAK1) inhibitor) in combination with epacadostat (indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor) or parsaclisib (phosphatidylinositol 3-kinase δ (PI3Kδ) inhibitor).

METHODS

Patients with advanced or metastatic solid tumors were enrolled and received itacitinib (100-400 mg once a day) plus epacadostat (50-300 mg two times per day; group A), or itacitinib (100-400 mg once a day) plus parsaclisib or parsaclisib monotherapy (0.3-10 mg once a day; group B).

RESULTS

A total of 142 patients were enrolled in the study. The maximum tolerated dose was not reached for either the combination of itacitinib plus epacadostat (n=47) or itacitinib plus parsaclisib (n=90). One dose-limiting toxicity of serious, grade 3 aseptic meningitis was reported in a patient receiving itacitinib 300 mg once a day plus parsaclisib 10 mg once a day, which resolved when the study drugs were withdrawn. The most common treatment-related adverse events among patients treated with itacitinib plus epacadostat included fatigue, nausea, pyrexia, and vomiting, and for patients treated with itacitinib plus parsaclisib were fatigue, pyrexia, and diarrhea. In the itacitinib plus epacadostat group, no patient had an objective response. Among patients receiving itacitinib 100 mg once a day plus parsaclisib 0.3 mg once a day, three achieved partial response for an objective response rate (95% CI) of 7.1% (1.50 to 19.48). Treatment with itacitinib plus epacadostat demonstrated some increase in tumor CD8⁺ T cell infiltration and minor changes in six plasma proteins, whereas treatment with itacitinib plus high-dose parsaclisib resulted in downregulation of 20 plasma proteins mostly involved in immune cell function, with no observed change in intratumoral CD8⁺ T cell infiltration.

CONCLUSION

Adverse events with JAK1 inhibition combined with either IDO1 or PI3Kδ inhibition were manageable, but the combinations demonstrated limited clinical activity or enhancement of immune activation in the tumor microenvironment.

TRIAL REGISTRATION NUMBER

NCT02559492.

Safety and early efficacy results from a phase 1, multicenter trial of PSMA-targeted armored CAR T cells in patients with advanced mCRPC

94

Background: CART-PSMA-02 is a multi-center, open-label, phase 1 trial evaluating the safety and feasibility of CART-PSMA-TGFβRDN T-cells (PSMA-CART) in patients (pts) with metastatic castration resistant prostate cancer (mCRPC). PSMA-CART are engineered to express a chimeric antigen receptor with specificity to PSMA and a dominant negative form of TGFβRII which renders PSMA-CART resistant to TGFβ-mediated immunosuppression. Herein, preliminary safety and efficacy results from this trial are reported. Methods: This is a 3+3 dose escalation study to determine the recommended phase 2 dose and schedule of PSMA-CART cells following lymphodepleting chemotherapy (LD) with cyclophosphamide and fludarabine. Results: As of October 2021, 9 pts were dosed. Two pts received 1-3x107 cells, 4 pts received 1-3x108 cells, and 3 pts received 0.7-1x108 cells with anakinra prophylaxis. Grade 1-2 CRS was observed in all pts receiving 1-3x108 cells and 2/3 pts who received anakinra prophylaxis. No pts developed CRS > G2. Two events of immune-effector cell associated neurotoxicity syndrome (ICANS) were observed (1 G2, 1 G5). Two pts experienced DLTs at dose level of 1-3x108, one of whom developed G5 events of ICANS and multi-organ failure (MOF) after receiving 30% of his fractionated dose (total dose = 0.9x108). This pt’s clinical course and autopsy findings were consistent with macrophage activation syndrome. The trial continued with a modified dose of 0.7-1x108 and the incorporation of prophylactic anakinra (100mg SC daily x7 doses). Another G5 event was observed, likely related to immune toxicity, with ferritin levels peaking at >100,000 ng/mL prior to death. Cause of death on autopsy was equivocal and contributing factors included metastatic prostate cancer, MOF and coagulopathy. Cytokine levels from both pts experiencing G5 events were elevated compared to all other pts (e.g., IL-6, sIL2RA, MIG/CXCL9, MIP1b/CCL4, IP-10/CXCL19, IL2 and IL1b). In pts receiving ≥ 0.9x108 cells (n=7), preliminary efficacy results demonstrated stable disease by RECIST v1.1 at day 28 (D28) in 4/5 evaluable pts. Decreases in serum PSA occurred in 4/7 pts with >50% decreases observed in 2/5 evaluable pts at D28. Conclusions: PSMA-CART has shown preliminary evidence of biological activity in the absence of clear indications of on-target/off-tumor toxicity. The exact mechanisms driving the severe immune-mediated toxicities in this study are currently unclear. While this study has been closed to further enrollment, ongoing research efforts are aimed at exploring patient specific factors, tumor microenvironment factors, and the PSMA-CART construct (including both functional components and armored modules) to design future constructs of PSMA-CART that will enhance the efficacy/safety profile and allow for continued study of this novel therapy in the clinic. Clinical trial information: NCT04227275.