First-in-human Phase I Trial of TPST-1120, an Inhibitor of PPARα, as Monotherapy or in Combination with Nivolumab, in Patients with Advanced Solid Tumors

PURPOSE

TPST-1120 is a first-in-class oral inhibitor of peroxisome proliferator-activated receptor α (PPARα), a fatty acid ligand-activated transcription factor that regulates genes involved in fatty acid oxidation, angiogenesis, and inflammation, and is a novel target for cancer therapy. TPST-1120 displayed antitumor activity in xenograft models and synergistic tumor reduction in syngeneic tumor models when combined with anti-PD-1 agents.

EXPERIMENTAL DESIGN

This phase I, open-label, dose-escalation study (NCT03829436) evaluated TPST-1120 as monotherapy in patients with advanced solid tumors and in combination with nivolumab in patients with renal cell carcinoma (RCC), cholangiocarcinoma (CCA), or hepatocellular carcinoma. Objectives included evaluation of safety, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity (RECIST v1.1).

RESULTS

A total of 39 patients enrolled with 38 treated (20 monotherapy, 18 combination; median 3 prior lines of therapy). The most common treatment-related adverse events (TRAE) were grade 1-2 nausea, fatigue, and diarrhea. No grade 4-5 TRAEs or dose-limiting toxicities were reported. In the monotherapy group, 53% (10/19) of evaluable patients had a best objective response of stable disease. In the combination group, 3 patients had partial responses, for an objective response rate of 20% (3/15) across all doses and 30% (3/10) at TPST-1120 ≥400 mg twice daily. Responses occurred in 2 patients with RCC, both of whom had previously progressed on anti-PD-1 therapy, and 1 patient with late-line CCA.

CONCLUSIONS

TPST-1120 was well tolerated as monotherapy and in combination with nivolumab and the combination showed preliminary evidence of clinical activity in PD-1 inhibitor refractory and immune compromised cancers.

SIGNIFICANCE

TPST-1120 is a first-in-class oral inhibitor of PPARα, whose roles in metabolic and immune regulation are implicated in tumor proliferation/survival and inhibition of anticancer immunity. This first-in-human study of TPST-1120 alone and in combination with nivolumab supports proof-of-concept of PPARα inhibition as a target of therapeutic intervention in solid tumors.

Brief Report: Safety and Antitumor Activity of Durvalumab Plus Tremelimumab in PD-(L)1-Monotherapy Pretreated, Advanced Non-Small Cell Lung Cancer: Results From a Phase 1b Clinical Trial

INTRODUCTION

While first-line immunotherapy approaches are standard, in patients with NSCLC previously treated with PD-1 or PD-L1 (PD-[L]1) inhibitors, the activity of combined CTLA-4 plus PD-L1 inhibition is unknown. This phase 1b study evaluated the safety and efficacy of durvalumab plus tremelimumab in adults with advanced NSCLC who received anti-PD-(L)1 monotherapy as their most recent line of therapy.

METHODS

Patients with PD-(L)1-relapsed/refractory NSCLC were enrolled between October 25, 2013, and September 17, 2019. Durvalumab 20 mg/kg plus tremelimumab 1 mg/kg was administered intravenously every 4 weeks (Q4W) for 4 doses, followed by 9 doses of durvalumab monotherapy Q4W for 12 months or disease progression. Primary endpoints included safety and objective response rate (ORR) based on RECIST version 1.1 per blinded independent central review (BICR); secondary endpoints were ORR based on RECIST 1.1 per investigator; duration of response, disease control, and PFS based on RECIST v1.1 per BICR and investigator; and OS.

RESULTS

PD-[L]1-refractory (n=38) and PD[L]1-relapsed (n=40) patients were treated. The most common treatment-related adverse events (TRAEs) were fatigue (26.3%, PD-[L]1-refractory patients) and diarrhea (27.5%, PD-[L]1-relapsed patients). Grade 3-4 TRAEs occurred in 22 patients. Median follow-up duration was 43.6 months for PD-(L)1-refractory patients and 41.2 months for PD-(L)1-relapsed patients. The ORR was 5.3% for PD-(L)1-refractory patients (1 complete response, 1 partial response) and 0% for PD-(L)1-relapsed patients.

CONCLUSIONS

Durvalumab plus tremelimumab had a manageable safety profile, but the combination did not show efficacy following PD-(L)1 treatment failure.

The application of autologous cancer immunotherapies in the age of memory-NK cells

Cellular immunotherapy has revolutionized the oncology field, yielding improved results against hematological and solid malignancies. NK cells have become an attractive alternative due to their capacity to activate upon recognition of "stress" or "danger" signals independently of Major Histocompatibility Complex (MHC) engagement, thus making tumor cells a perfect target for NK cell-mediated cancer immunotherapy even as an allogeneic solution. While this allogeneic use is currently favored, the existence of a characterized memory function for NK cells ("memory-like" NK cells) advocates for an autologous approach, that would benefit from the allogeneic setting discoveries, but with added persistence and specificity. Still, both approaches struggle to exert a sustained and high anticancer effect in-vivo due to the immunosuppressive tumor micro-environment and the logistical challenges of cGMP production or clinical deployment. Novel approaches focused on the quality enhancement and the consistent large-scale production of highly activated therapeutic memory-like NK cells have yielded encouraging but still unconclusive results. This review provides an overview of NK biology as it relates to cancer immunotherapy and the challenge presented by solid tumors for therapeutic NKs. After contrasting the autologous and allogeneic NK approaches for solid cancer immunotherapy, this work will present the current scientific focus for the production of highly persistent and cytotoxic memory-like NK cells as well as the current issues with production methods as they apply to stress-sensitive immune cells. In conclusion, autologous NK cells for cancer immunotherapy appears to be a prime alternative for front line therapeutics but to be successful, it will be critical to establish comprehensives infrastructures allowing the production of extremely potent NK cells while constraining costs of production.

Survival, Durable Tumor Remission, and Long-Term Safety in Patients With Advanced Melanoma Receiving Nivolumab

PURPOSE

Programmed cell death 1 (PD-1) is an inhibitory receptor expressed by activated T cells that downmodulates effector functions and limits the generation of immune memory. PD-1 blockade can mediate tumor regression in a substantial proportion of patients with melanoma, but it is not known whether this is associated with extended survival or maintenance of response after treatment is discontinued.

PATIENTS AND METHODS

Patients with advanced melanoma (N = 107) enrolled between 2008 and 2012 received intravenous nivolumab in an outpatient setting every 2 weeks for up to 96 weeks and were observed for overall survival, long-term safety, and response duration after treatment discontinuation.

RESULTS

Median overall survival in nivolumab-treated patients (62% with two to five prior systemic therapies) was 16.8 months, and 1- and 2-year survival rates were 62% and 43%, respectively. Among 33 patients with objective tumor regressions (31%), the Kaplan-Meier estimated median response duration was 2 years. Seventeen patients discontinued therapy for reasons other than disease progression, and 12 (71%) of 17 maintained responses off-therapy for at least 16 weeks (range, 16 to 56+ weeks). Objective response and toxicity rates were similar to those reported previously; in an extended analysis of all 306 patients treated on this trial (including those with other cancer types), exposure-adjusted toxicity rates were not cumulative.

CONCLUSION

Overall survival following nivolumab treatment in patients with advanced treatment-refractory melanoma compares favorably with that in literature studies of similar patient populations. Responses were durable and persisted after drug discontinuation. Long-term safety was acceptable. Ongoing randomized clinical trials will further assess the impact of nivolumab therapy on overall survival in patients with metastatic melanoma.

Phase I Study of Single-Agent Anti-Programmed Death-1 (MDX-1106) in Refractory Solid Tumors: Safety, Clinical Activity, Pharmacodynamics, and Immunologic Correlates

PURPOSE

Programmed death-1 (PD-1), an inhibitory receptor expressed on activated T cells, may suppress antitumor immunity. This phase I study sought to determine the safety and tolerability of anti-PD-1 blockade in patients with treatment-refractory solid tumors and to preliminarily assess antitumor activity, pharmacodynamics, and immunologic correlates.

PATIENTS AND METHODS

Thirty-nine patients with advanced metastatic melanoma, colorectal cancer (CRC), castrate-resistant prostate cancer, non-small-cell lung cancer (NSCLC), or renal cell carcinoma (RCC) received a single intravenous infusion of anti-PD-1 (MDX-1106) in dose-escalating six-patient cohorts at 0.3, 1, 3, or 10 mg/kg, followed by a 15-patient expansion cohort at 10 mg/kg. Patients with evidence of clinical benefit at 3 months were eligible for repeated therapy.

RESULTS

Anti-PD-1 was well tolerated: one serious adverse event, inflammatory colitis, was observed in a patient with melanoma who received five doses at 1 mg/kg. One durable complete response (CRC) and two partial responses (PRs; melanoma, RCC) were seen. Two additional patients (melanoma, NSCLC) had significant lesional tumor regressions not meeting PR criteria. The serum half-life of anti-PD-1 was 12 to 20 days. However, pharmacodynamics indicated a sustained mean occupancy of > 70% of PD-1 molecules on circulating T cells ≥ 2 months following infusion, regardless of dose. In nine patients examined, tumor cell surface B7-H1 expression appeared to correlate with the likelihood of response to treatment.

CONCLUSION

Blocking the PD-1 immune checkpoint with intermittent antibody dosing is well tolerated and associated with evidence of antitumor activity. Exploration of alternative dosing regimens and combinatorial therapies with vaccines, targeted therapies, and/or other checkpoint inhibitors is warranted.

Epacadostat Plus Pembrolizumab and Chemotherapy for Advanced Solid Tumors: Results from the Phase I/II ECHO-207/KEYNOTE-723 Study

BACKGROUND

Epacadostat, an oral, selective inhibitor of IDO1, has shown activity when administered with pembrolizumab. We evaluated the addition of chemotherapy to epacadostat and pembrolizumab in patients with advanced or metastatic solid tumors. One proposed mechanism of resistance to PD-1 checkpoint inhibition is through immunosuppression mediated by L-kynurenine. IDO1, indoleamine-2,3-dioxygenase 1 is the rate-limiting enzyme catalyzing the conversion of L-tryptophan to L-kynurenine. If IDO1 is a mechanism of tumor escape from checkpoint inhibition, then addition of an IDO1 inhibitor with a PD-1 checkpoint inhibitor could enable tumor response to immunotherapy.

METHODS

Patients received one of 7 tumor-appropriate chemotherapy regimens. Pembrolizumab 200 mg was infused intravenously every 3 weeks. Epacadostat 100 mg was administered orally twice daily. The primary objectives of phase I were determining safety/tolerability and defining the maximum tolerated or pharmacologically active dose of epacadostat. Phase II of the study was designed to enroll efficacy-expansion cohorts and to assess changes in the tumor and tumor microenvironment via mandatory-biopsy cohorts.

RESULTS

A total of 70 patients were enrolled. Twelve patients were enrolled in the phase II mandatory-biopsy cohorts. Due to early study closure, efficacy expansion did not enroll. Grades 3 and 4 treatment-emergent adverse events (TEAEs) occurred in 78.6% of patients. Neutropenia and disease progression were the only grades 3 and 4 TEAEs reported in ≥10.0% of patients. One treatment-related death was reported. The ORR was 31.4% across all treatment groups.

CONCLUSION

The combination of epacadostat 100 mg bid with pembrolizumab and chemotherapy had an acceptable safety profile. This regimen showed antitumor activity across multiple types of advanced or metastatic solid tumors (ClinicalTrials.gov Identifier: NCT03085914).

IL believe: A phase 1/2, open-label, dose escalation and dose expansion study of TransCon IL-2 β/γ alone or in combination with pembrolizumab or standard-of-care chemotherapy in patients with locally advanced or metastatic solid tumors

TPS2695

Background: Advances in immunotherapy have led to significantly improved survival and quality of life in some cancer patients, but many with less immunogenic tumor types derive suboptimal clinical benefit. Recombinant human interleukin-2 (IL-2, aldesleukin) can induce a response rate of ̃15% in metastatic renal cell carcinoma and metastatic melanoma, yet toxicities (vascular leak syndrome, cytokine storm) have limited its use. TransCon IL-2 β/γ, a novel prodrug with sustained release of a receptor-selective IL-2 (IL-2 β/γ), was designed to optimally address drawbacks of aldesleukin: potent activation of undesired IL-2Rα+ cell types and high Cmax with rapid clearance. TransCon IL-2 β/γ comprises 3 main components: IL-2 β/γ, a methoxy polyethylene glycol (mPEG) carrier molecule, and a linker connecting the two. Under physiological conditions, TransCon IL-2 β/γ releases active IL-2 β/γ from the mPEG carrier through cleavage of the TransCon Linker. This results in a lower Cmax and much longer effective t½ of free IL-2 β/γ compared to aldesleukin. PD-1 expression at the cell surface of activated cytotoxic T cells and natural killer cells provides a clear rationale to study TransCon IL-2 β/γ alone or in combination with pembrolizumab. Methods: IL Believe is a multicenter, first-in-human, Phase 1/2 study in 3 parts in adult patients with locally advanced or metastatic solid tumors. All patients need ≥1 measurable lesion per RECIST 1.1 and an ECOG score of ≤ 2. The primary objectives are to evaluate safety and tolerability, and to define the maximum tolerated dose and recommended Phase 2 dose (RP2D) of TransCon IL-2 β/γ alone or in combination with pembrolizumab. Parts 1 and 2 Dose Escalation (Phase 1) use a standard 3+3 design with increasing doses of intravenous (IV) TransCon IL-2 b/g alone (Part 1) or with 200 mg IV pembrolizumab in solid tumors where pembrolizumab monotherapy may have clinical activity (Part 2). Each part will enroll ̃15 patients. Part 3, Combination Dose Expansion (Phase 2) will evaluate preliminary clinical efficacy of TransCon IL-2 β/γ at the RP2D determined in Part 2, combined with chemotherapy. Platinum Resistant Ovarian Cancer is currently planned for dose expansion with other indication specific cohorts to be included in a subsequent amendment. Each cohort will be analyzed using a Simon 2-stage design and will enroll ̃56 patients. Other key objectives include the evaluation of pharmacokinetics, pharmacodynamic biomarkers, and antitumor activity according to RECIST 1.1. Recruitment started in January 2022 and is ongoing (NCT05081609). Clinical trial information: NCT05081609.

A first-in-human, multicenter, phase 1/2, open-label study of XTX202, a masked and tumor-selective recombinant human interleukin-2 (IL-2) protein, in patients with advanced solid tumors

TPS2697

Background: High-dose interleukin-2 (IL-2) has been approved in metastatic renal cell carcinoma (RCC) and metastatic melanoma, and can result in durable complete responses, including cures. Its use has been limited by life-threatening treatment-related multisystem toxicities, consisting mainly of vascular leak syndrome. XTX202 is a masked, tumor-selective IL-2 that is designed to be pharmacologically inactive in non-tumor tissue when circulating systemically and unmasked by matrix metalloproteases (MMPs) found preferentially in the tumor microenvironment (TME). XTX202 is expected, therefore, to achieve a wider therapeutic index resulting in increased efficacy and lower toxicity compared to existing non-tumor selective IL-2 based-therapies. The IL-2 domain of the XTX202 molecule is modified to reduce binding to the high-affinity IL-2 receptor while maintaining binding to the intermediate-affinity IL-2 receptor, thereby decreasing activation of regulatory T-cells relative to wild-type IL-2, while still activating effector T cells. A masking domain is designed to pharmacologically inactivate IL-2 until it is activated by MMPs that are enriched in the TME. Cleavage at a protease cleavage site in the XTX202 linker by MMPs results in an active IL-2 moiety when the masking domain is released. XTX202 is designed with the goal of producing a localized anti-tumor immune response and limiting exposure of the active form of XTX202 in non-tumor tissue. Preclinically, XTX202 exhibited tumor-selective activity in mice without peripheral toxicities in non-human primates [O’Neil et al. ASCO 2021]. Methods: XTX202-01 trial (NCT05052268) is a first-in-human Phase 1/2 study to determine a recommended Phase 2 dose of XTX202 (Phase 1) and to evaluate the efficacy of XTX202 monotherapy in patients with metastatic RCC and unresectable or metastatic melanoma (Phase 2). Patients with advanced solid tumors are eligible for Phase 1 and will receive XTX202 monotherapy administered every 21 days in an accelerated and standard 3+3 dose escalation design. Phase 2 will consist of 2 parts: Part 2a will enroll patients with metastatic RCC who have received a prior tyrosine kinase inhibitor therapy and have been treated and progressed on an anti-PD-1 therapy. Part 2b will enroll patients with unresectable or metastatic melanoma who have received immune-checkpoint therapy with an anti-PD-1 therapy and an anti-CTLA-4 therapy to determine the efficacy of XTX202 monotherapy in this population. Enrollment to the study began in January 2022. Clinical trial information: NCT05052268.

Phase Ia dose-escalation study of the anti-BTLA antibody icatolimab as a monotherapy in patients with advanced solid tumor

2643

Background: The B- and T-lymphocyte attenuator (BTLA) is an inhibitory receptor expressed on B, T and NK cells. Icatolimab (TAB004 or JS004) is a humanized IgG4 monoclonal antibody (mAb) with a hinge mutation (S228P) that binds BTLA and blocks its interaction with its ligand HVEM. In preclinical studies, icatolimab monotherapy suppressed tumor growth in murine tumor models using human BTLA knock-in mice. In this first-in-human dose-escalation study, we report the preliminary safety and efficacy of icatolimab as a single agent in patients with advanced solid tumors. Methods: Eligible patients with advance solid tumors refractory to standard therapies were enrolled in this study. Icatolimab was administered at escalating doses of 0.3, 1, 3 and 10 mg/kg intravenously Q3W and followed by dose expansion in 3 and 10 mg/kg cohorts until disease progression or intolerable toxicity. Dose-limiting toxicity (DLT) was evaluated by a safety monitoring committee. Study objectives included safety, pharmacokinetics, pharmacodynamics, and anti-tumor activity. Results: A total of 25 patients with solid tumor were enrolled in the Part A of this phase I study (NCT04137900). The median age was 62 (range 32-85) years with 16 (64%) male patients. Patients were heavily pretreated with a median of 4 prior lines of therapy. Fifteen (60%) patients received and progressed upon prior anti-PD-1/L1 therapy. By the data cutoff date of December 31, 2021, the median follow-up was 32 weeks. No DLT was observed. 24 (96%) patients experienced treatment emergent adverse event (TEAEs), with 7 (28%) experienced grade 3 TEAEs. No grade 4 or 5 TEAE occurred. The incidence or severity of AE was not associated with the dose. The most common TEAEs were fatigue (32%), abdominal pain (20%), diarrhea (16%), arthralgia (16%), aspartate aminotransferase increased (16%), constipation (16%), and contusion (16%). One (4%) TEAE led to discontinuation of study drug. Four (16%) patients experienced immune related AE. Among 19 evaluable patients by the cutoff date, 1 confirmed PR (melanoma) and 6 SD were observed as assessed by the investigator per RECIST v1.1. The response was still ongoing over 12 months in the melanoma patient who had progressed upon prior nivolumab and BRAF/MEK inhibitors treatments. BTLA receptor was fully occupied in the 3 and 10 mg/kg cohorts. The mean elimination half-life of icatolimab was 7.5 to 19.2 days in four dose cohorts. Biomarker analysis indicated co-expression of HVEM and CD8 was associated with favorable response. Conclusions: Icatolimab monotherapy were well tolerated in all doses evaluated and showed preliminary clinical efficacy as a monotherapy. Icatolimab in combination with toripalimab (anti-PD-1) for the treatment of patients with advanced solid tumors is currently ongoing. Clinical trial information: NCT04137900.

Phase 1/2 dose escalation study of NUV-422, a potent inhibitor of cyclin-dependent kinases 2, 4, and 6, in recurrent or refractory (r/r) high-grade gliomas (HGG) and solid tumors

TPS3173

Background: CDKs that govern the G1-S transition of the cell cycle (CDK2, CDK4 and CDK6) are deregulated in many cancers. CDK2 expression, in particular, is associated with worse overall survival in glioblastoma (GB), disease-free recurrence in prostate cancer, and resistance to approved CDK4/6 inhibitors (CDK4/6i) in breast cancer. These provide rationale for inhibition of CDK2/4/6 as a potential novel therapeutic strategy in these cancers. NUV-422 is a potent (low nM) small molecule CDK2/4/6i with limited activity against CDK1, a target potentially associated with toxicities in other CDKi. Preclinical studies have shown that NUV-422 has favorable blood-brain barrier penetration, inhibited growth of multiple glioma cell lines in vitro, and exhibited antitumor activity in GB xenograft models. NUV-422 also exhibited antitumor activity in multiple patient-derived xenograft (PDX) models of HR+ HER2- mBC resistant to CDK4/6i, and PDX models of prostate cancer resistant to anti-androgens. Methods: NUV-422-02 (NCT04541225) is a phase 1/2, first in human, open label, multicenter study to evaluate single-agent NUV-422 (given orally) in patients with advanced solid tumors (r/r HGG, r/r HR+ HER2- mBC, or r/r mCRPC). The Ph 1 dose escalation will use a 3+3 design to evaluate safety, tolerability, and PK of NUV-422 and establish the recommended phase 2 dose (RP2D). Ph 1 also includes a randomized surgical substudy to characterize PK and pharmacodynamics (PD) of preoperative NUV-422 in resected GB tumor tissue. After the RP2D is identified, parallel enrollment into phase 2 expansion cohorts will begin. Cohort 1 will evaluate isocitrate dehydrogenase wild type (IDH-WT) GB. Cohort 2 will evaluate HR+ HER2- mBC (without active brain metastases); Cohort 3 will evaluate mCRPC; and Cohort 4 will evaluate HR+ HER2- mBC with active brain metastases. The Ph 2 primary endpoint is objective response rate. Secondary efficacy endpoints include clinical benefit rate, duration of response, progression-free survival, and overall survival. Response assessments will be based on response criteria appropriate to the tumor type (HGG [RANO]; HR+HER2- mBC [RECIST 1.1 or RANO-Brain Metastases]; mCRPC [RECIST 1.1, PCWG3, prostate-specific antigen decrease]). Blood, urine, or tumor tissue will be obtained to assess safety, PK, PD, and for additional exploratory analyses to characterize NUV-422 mechanism of action. Enrollment was initiated in December 2020, and dose escalation is ongoing. The NUV-422 program will also be expanded in 2022 to include additional studies in mBC and mCRPC in combination with standard of care treatments. Clinical trial information: NCT04541225.

A phase 1 study of TPST-1495 as a single agent and in combination with pembrolizumab in subjects with solid tumors

TPS2696

Background: Prostaglandin E2 (PGE2) is a bioactive lipid that promotes cancer through diverse mechanisms including stimulating tumor proliferation, enhancing angiogenesis and suppressing immune function in the tumor microenvironment. PGE2 produced by tumor cells through upregulation of cyclooxygenase-2 (COX-2) is also a key mediator of adaptive resistance to immune checkpoint inhibitor therapy. While PGE2 signaling is important in cancer, how best to inhibit PGE2 for cancer treatment is under investigation. Inhibition of COX enzymes (e.g., with NSAIDS) has shown promise in large observational studies, but inconsistent results in prospective studies. Importantly, COX inhibition alters multiple prostanoids beyond PGE2, resulting in toxicity that limits therapeutic dosing for cancer. PGE2 signals through four receptors, EP1-4, that are variably expressed and have distinct activities. The tumor promoting and immunosuppressive activities of PGE2 predominantly arise from signaling through the EP2 and EP4 receptors, while signaling through the EP1 and EP3 receptors generally is pro-inflammatory. TPST-1495 is designed to be an oral, highly specific, antagonist of the EP2 and EP4 receptors, sparing the EP1 and EP3 receptors and the COX enzymes. Preclinical studies suggest that blocking EP2 and EP4 with TPST-1495 inhibits tumor proliferation and stimulates anti-cancer immunity better than inhibiting all 4 receptors together, the EP2 or EP4 receptors singly, or the upstream COX-2 enzyme. Methods: TPST-1495-001 is a first-in-human Phase 1 study (NCT04344795). In the Dose and Schedule Optimization Stage, the primary objectives are to characterize the safety and tolerability (including dose limiting toxicities) and determine the recommended phase 2 dose (RP2D) of TPST-1495 as monotherapy and in combination with pembrolizumab in patients with advanced solid tumors. Additional objectives include characterization of PK, PD, and evaluation of potential biomarkers, including through paired (pre- and on-treatment) tumor biopsies. Monotherapy dose-finding employs a modified 3+3 design evaluating BID and QD TPST-1495 schedules along with continuous or intermittent (Days 1-5 every 7 days) dosing. For the pembrolizumab combination, the starting dose and schedule of TPST-1495 are determined by safety, PK and PD of monotherapy. Indication-specific Expansion Stage cohorts will evaluate TPST-1495 at the selected RP2D and schedule for both monotherapy and combination in endometrial cancer, squamous cell carcinoma of the head and neck, and microsatellite stable colorectal cancer (combination only), as well as in a biomarker-specific cohort enrolling patients with pathogenic tumor PIK3CA gene mutation. Dose and Schedule Optimization enrollment (monotherapy and combination) is ongoing at abstract submission while Expansion Stages are planned after identification of the RP2Ds. Clinical trial information: NCT04344795.

A phase 1 study of TPST-1120 as a single agent and in combination with nivolumab in subjects with advanced solid tumors

3005

Background: TPST-1120 is a first-in-class oral therapy that inhibits PPARα, a transcription factor that regulates fatty acid oxidation (FAO). TPST-1120 has diverse mechanisms of anti-tumor activity in preclinical studies, including inhibiting tumor proliferation, increasing the anti-angiogenic factor thrombospondin 1, and reducing T cell exhaustion. Methods: Subjects with advanced solid tumor malignancies received escalating doses of TPST-1120 as a single agent or in combination with nivolumab 480 mg IV every 4 weeks (combination cohort limited to RCC, cholangiocarcinoma [CCA] and HCC). Study objectives included evaluation of safety, pharmacokinetics, MTD, RP2D and anti-tumor activity as monotherapy and in combination with nivolumab. AEs were assessed per CTCAE v5 and efficacy per RECIST v1.1 Results: As of 14-Jan-2022, 35 subjects have been dosed (20 with TPST-1120 monotherapy at doses from 100 mg to 600 mg PO BID and 15 in combination with nivolumab at doses from 200 mg to 600 mg PO BID). Median prior lines of systemic therapy were 3 (2-11) in monotherapy and 2 (2-6) in combination cohorts. An MTD was not reached in monotherapy or combination, and the TPST-1120 RP2D was 600 mg PO BID for both cohorts. For TPST-1120 monotherapy, the most common treatment related AEs (TRAEs) were nausea (20%), fatigue (15%), and diarrhea (10%), all Grade 1-2. One monotherapy subject (5%) experienced a Grade 3 TRAE (hypertension). In the combination cohort the most common TRAEs related to either drug were fatigue (40%), diarrhea (27%) and nausea (20%), all Grade 1-2. Three combination subjects (19%) experienced Grade 3 TRAEs (one each arthralgia, hepatic enzyme increased, muscle spasms). A best response of stable disease was observed in 53% (10/19) of subjects treated with monotherapy. In combination, the ORR was 23% (3/13, all PRs) across all dose levels and 38% (3/8) at TPST-1120 dose levels ≥400 mg BID. These responses included 2 subjects with late-line RCC (2/2 RCC subjects enrolled, both with progression on prior anti-PD1 therapy) and one subject with heavily pre-treated CCA. At data cut off, 2 of 3 responding patients (CCA and one RCC) remained in PR and on study at 8.4 and 14 mo, respectively. Conclusions: TPST-1120 is a novel therapy designed to inhibit tumor proliferation and angiogenesis and stimulate anti-cancer immunity through inhibition of PPARα, a key regulator of FAO. The drug is well tolerated as a single agent and in combination with nivolumab. Promising objective responses have been observed in combination with nivolumab in subjects previously refractory to anti-PD-1 therapy, including 2/2 responders in late-line RCC, and a subject with heavily pretreated CCA, a tumor type generally not responsive to anti-PD-1 alone. Notably, all responders were treated at the two highest doses of TPST-1120 (ORR 38%). Updated study results including exploratory biomarkers will be presented. Clinical trial information: NCT03829436.

Rationale and design of phase 1 FTIH study of FOXP3 antisense oligonucleotide AZD8701 in patients with selected advanced solid tumors

TPS3166

Background: The forkhead box family transcription factor FOXP3 is essential for T regulatory cells (Tregs) development and immune suppressive function. Tregs are an integral component of the adaptive immune system and contribute to maintaining tolerance to self-antigens and preventing autoimmune diseases. In the context of cancer, however, Tregs contribute to tumor progression by suppressing antitumor immunity. To date inhibition of Treg-mediated immunosuppression tested in the clinic has lacked specificity. Targeting FOXP3 provides a selective approach to impair the immunosuppressive function of Tregs but targeting transcription factors has been a challenge using conventional drug modalities. AZD8701 employs next-generation antisense oligonucleotide (ASO) technology (Ionis Pharmaceuticals) to bind mRNA with high affinity and selectively reduce human Foxp3 mRNA expression levels. Foxp3-specific ASOs promote potent dose-dependent reductions in Foxp3 mRNA and protein in vitro. In preclinical models, AZD8701 induced Foxp3 knockdown results in Tregs with a reduced immunosuppressive capacity, loss of immunosuppressive markers, and increased markers of activation on CD8+ T-cells. AZD8701 reduces tumor growth as monotherapy in preclinical models and increased tumor inhibition is obtained by combining AZD8701 with a PD-L1 inhibitor. Methods: This is a Phase I multicenter study of AZD8701 alone or in combination with durvalumab in participants with selected advanced solid tumors. Eligible patients must have ECOG performance status 0 or 1, measurable target lesion per RECIST v1.1 and be diagnosed with selected tumor types as described below. Monotherapy and combination dose escalation phase is open for participants with head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), non-small-cell lung cancer (NSCLC), clear cell renal cell carcinoma (ccRCC), gastroesophageal cancer, melanoma, cervical cancer, small-cell lung cancer (SCLC), and/or solid tumors that have demonstrated a response to prior programmed death-ligand-1 (PD-[L]1) treatment (as defined by duration of response > 18 weeks). Participants with NSCLC, HNSCC, TNBC, and ccRCC will be included in the pharmacodynamic cohort at the selected monotherapy dose and/or disease expansion cohorts. The primary objectives are to assess safety and tolerability and to determine the preliminary antitumor activity of AZD8701 (objective response rate) when administered as monotherapy or in combination with durvalumab. Secondary endpoints include, disease control rate, duration of response, progression free survival and overall survival, pharmacokinetics and pharmacodynamics (including changes in Foxp3 mRNA in paired tumor samples). The trial is currently recruiting. Clinical trial information: NCT04504669.

A phase 1 dose-escalation study to investigate the safety, efficacy, pharmacokinetics, and pharmacodynamic activity of CLN-619 (anti-MICA/MICB antibody) alone and in combination with pembrolizumab in patients with advanced solid tumors

TPS2688

Background: The major histocompatibility complex (MHC) class I-related proteins MICA and MICB are stress-inducible, surface glycoproteins that are up-regulated on human tumors. MICA/MICB are ligands for the activating receptor, Natural Killer Group 2 member D (NKG2D) expressed on Natural Killer (NK) cells, CD8+ T cells, γδ T cells and iNKT cells. Proteases in the tumor microenvironment cleave MICA/MICB from the cell surface which enables tumor cells to evade immune cell recognition and destruction by NKG2D-expressing cells. Increased concentrations of shed MICA have been observed in serum from patients across multiple tumor types and correlate with poor survival. CLN-619 is a humanized, clinical-stage, MICA/MICB-specific IgG1 monoclonal antibody that prevents the proteolytic release of MICA/MICB thereby exposing tumor cells for immune destruction through both NKG2D-mediated and antibody-dependent cell-mediated cytotoxicity (ADCC). The antibody has been shown to restore the MICA/MICB-NKG2D axis to promote NK-mediated tumor cell lysis (AACR Annual Meeting abstract 3506, April 2022). In mice bearing MICA/MICB-expressing human tumor xenografts, CLN-619 treatment yielded robust anti-tumor activity at low doses. MICA/MICB is expressed in a wide range of solid tumors. Therefore, CLN-619 is expected to have broad anti-tumor activity. Methods: CLN-619 is being evaluated in an open-label, non-randomized, dose-escalation (phase 1) study as monotherapy, and in combination with pembrolizumab, in patients with advanced solid tumors. Cohort expansion in patients with specific indications as monotherapy and in combination with pembrolizumab will be conducted. The phase 1 study explores ascending intravenous doses of CLN-619 as monotherapy (0.1, 0.3, 1.0, 3.0, 6.0 and 10.0 mg/kg) and in combination with pembrolizumab (200 mg) in 21-day cycles to identify the maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D). Key eligibility criteria include 1) histological or cytological diagnosis of cancer and 2) refractory metastatic disease, or locally advanced disease not amenable to local therapy. At the RP2D, CLN-619 monotherapy will be evaluated in non-small cell lung and cervical cancer. In parallel, a cohort of patients will be administered CLN-619 in combination with pembrolizumab. Serum levels of soluble MICA/MICB, identity of MICA/MICB alleles, phenotypes of peripheral blood mononuclear cells, cytokines and tumor biopsies will be investigated for correlative pharmacodynamic and predictive biomarkers. This clinical trial is in progress (NCT05117476) and has completed accrual of three participants at the first dose level. Clinical trial information: NCT05117476.

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.

A first-in-human study of mirzotamab clezutoclax as monotherapy and in combination with taxane therapy in relapsed/refractory solid tumors: Dose escalation results

3015

Background: Mirzotamab clezutoclax (ABBV-155) is a first-in-class antibody drug conjugate comprised of a BCL-XL (B-cell lymphoma - extra long) inhibitor, solubilizing linker, and a monoclonal anti-B7H3 antibody. Methods: Patients (pts) with relapsed and/or refractory (R/R) solid tumors were administered mirzotamab clezutoclax with or without paclitaxel. Dose escalation of mirzotamab clezutoclax was guided by Bayesian continual reassessment. Primary outcomes were to determine the maximum tolerated dose (MTD) and the recommended phase 2 dose (RP2D). Secondary outcomes: safety, pharmacokinetics, and overall response rate per RECIST v1.1. Results: As of November 6, 2020, 31 pts received mirzotamab clezutoclax monotherapy (monoTx) and 28 pts received combination therapy with paclitaxel (comboTx). Overall demographics: median age 62 years (range 25–79); 61% female; 86% white; 24% ECOG 0, 76% ECOG 1; 51% had > 3 prior systemic therapies. The median duration of mirzotamab clezutoclax exposure was 3 cycles (range 1–14) for monoTx and 5 cycles (range 1–14) for comboTx. There were no dose limiting toxicities (DLT) reported with monoTx. In comboTx, 2 pts experienced a DLT: Grade 4 neutrophil count decreased and Grade 3 lymphocyte count decreased considered related to paclitaxel. 97% of all pts had adverse events (AEs). The most common AEs (in ≥20% of pts) overall were fatigue (39%), nausea (25%), diarrhea and arthralgia (22% each), vomiting and hypokalemia (20% each). AEs in ≥5 pts related to mirzotamab cleuzutoclax were fatigue (27%), diarrhea (12%), and nausea (9%). Related Grade 3/4 AEs overall (in > 1 patient) included anemia, lymphocyte count decreased, fatigue, and diarrhea (3% each). One patient on monoTx experienced a fatal cardiac arrest. No fatal AEs occurred on comboTx. Responses were observed with comboTx as shown in the Table. Conclusions: Mirzotamab clezutoclax as monotherapy and with paclitaxel demonstrates a tolerable safety profile (MTD not reached) with anti-tumor activity in R/R solid tumors. Further investigation in prospectively-selected B7H3 positive tumors as monoTx in pts with R/R small cell lung cancer and with paclitaxel in pts with R/R breast cancer and docetaxel in pts with R/R non-small cell lung cancer in the dose expansion phase is ongoing. Clinical trial information: NCT03595059. [Table: see text]

Phase 1 dose escalation study of MGC018, an anti-B7-H3 antibody-drug conjugate (ADC), in patients with advanced solid tumors

2631

Background: MGC018 is an investigational ADC with a duocarmycin payload linked to an anti-B7-H3 monoclonal antibody (mAb). B7-H3 is expressed on multiple solid tumors with limited normal tissue expression. It is hypothesized that MGC018 may exert activity against B7-H3-expressing tumors with an acceptable safety profile. Studies demonstrate that B7-H3 is a significant factor in progression and events of metastasis of multiple tumor types, including melanoma. Methods: This phase 1 study characterizes safety, maximum tolerated or maximum administered dose, pharmacokinetics, immunogenicity, and tumor response per RECIST v1.1 of MGC018 in a 3+3+3 dose escalation design in patients with advanced solid tumors. MGC018 was administered intravenously (IV) every 3 weeks. Results: The study enrolled 29 patients of multiple tumor types, which included 3 melanoma patients refractory to ≥2 prior lines of checkpoint therapy. The study completed 5 of 6 planned dose cohorts (0.5 mg/kg - 4 mg/kg) as of the data cutoff of 21 January 2021. The final cohort of 4 mg/kg has 3 patients with ongoing treatment and follow-up at the date of submission. Dosing MGC018 IV every 3 weeks resulted in minimal serum accumulation. At least 1 treatment emergent adverse event occurred in 29 patients (100.0%); most common (≥25%) were anemia, neutropenia, fatigue, hyperpigmentation, infusion related reaction, nausea, and palmar plantar erythrodysesthesia. Two dose-limiting toxicities occurred; one grade 4 neutropenia (2 mg/kg) and one grade 3 fatigue lasting 7 days (4 mg/kg). No febrile neutropenia was reported. The 3 melanoma patients had reductions in target lesion sum of 24.4%, 27.5%, and 35% (unconfirmed partial response) and remain on treatment as of the data cutoff. The recommended phase 2 dose was determined to be 3 mg/kg. Conclusions: Results to date demonstrate a manageable safety profile, with early evidence of clinical activity in pretreated metastatic melanoma. Cohort expansion is ongoing using a recommended phase 2 dose of 3 mg/kg IV every 3 weeks. The planned enrollment includes advanced metastatic castrate-resistant prostate cancer, melanoma, triple-negative breast cancer, and non-small cell lung cancer. Clinical trial information: NCT03729596.

Selection of the recommended phase 2 dose (RP2D) for subcutaneous nemvaleukin alfa: ARTISTRY-2

2552

Background: Nemvaleukin alfa (nemvaleukin, ALKS 4230) is a novel engineered cytokine that selectively binds the intermediate-affinity interleukin-2 receptor to preferentially activate CD8+ T and natural killer (NK) cells with minimal expansion of regulatory T cells (Tregs),designed for use as a cancer immunotherapy. ARTISTRY-2 (NCT03861793) is an ongoing phase 1/2 study evaluating the safety, efficacy, and pharmacokinetic and pharmacodynamic (PD) responses of subcutaneous (SC) nemvaleukin in combination with pembrolizumab in patients (pts) with advanced solid tumors. Methods: In phase 1, cohort-specific doses of SC nemvaleukin are administered on an every-7-day (q7d) or every-21-day (q21d) schedule during a 6-week monotherapy lead-in period, followed by combination with pembrolizumab 200 mg q21d. We present safety, PD effects, and preliminary clinical activity outcomes as of 12/02/2020. Results: 57 pts received nemvaleukin doses ranging from 0.3 mg to 6 mg q7d or 1 mg to 10 mg q21d. The most frequent tumor types (> 5 pts) were colorectal, pancreatic, ovarian, and lung; median number of prior therapies was 4. Treatment-related adverse events (TRAEs) in > 30% pts overall were pyrexia (43.9%), chills (38.6%), injection site erythema (33.3%), injection site reaction (33.3%), and fatigue (31.6%). 3 mg q7d (n = 7) had no drug-related dose reductions, discontinuations, or deaths during the monotherapy or combination periods. 6 mg was declared the maximum tolerated dose (MTD) for q7d dosing as 2 of 8 pts experienced dose-limiting toxicities (DLTs). For 6 mg q21d (n = 7), no drug-related dose reductions, discontinuations, or deaths have occurred during the monotherapy period; combination period data are not mature. 10 mg was declared the MTD for q21d dosing as 1 of 9 pts experienced DLTs and 3 had TRAEs leading to dose reductions. Systemic exposure to nemvaleukin increased with increasing dose. Increases in NK cells and CD8+ T cells of approximately 16-fold and 3-fold, respectively, at 3 mg q7d, and approximately 8-fold and 3-fold, respectively, at 6 mg q21d were observed, with minimal change in Tregs. 46 pts had at least 1 on-treatment scan as of the data cutoff date, and 30 (65%) had stable disease (SD) on the first scan. Of the 30 pts with ≥2 scans, 13 (43%) had 2+ consecutive scans of SD. 16 of 57 pts remain on therapy. Antitumor activity data for more recent cohorts are still maturing. Based on the totality of the safety, PD effects, and antitumor activity data, 3 mg q7d was selected as the RP2D for SC nemvaleukin. Conclusions: SC nemvaleukin 3 mg q7d was generally well tolerated as monotherapy and in combination with pembrolizumab, and demonstrated robust PD effects on NK cells and CD8+ T cells with minimal expansion of Tregs. These PD effects are similar to or greater than those observed with intravenous nemvaleukin. Thus, 3 mg q7d was selected as RP2D; phase 2 expansion cohorts for combination with pembrolizumab are enrolling. Clinical trial information: NCT03861793.

First-in-Human Phase I Study of ABBV-085, an Antibody-Drug Conjugate Targeting LRRC15, in Sarcomas and Other Advanced Solid Tumors

PURPOSE

Leucine-rich repeat containing 15 (LRRC15) is expressed on stromal fibroblasts in the tumor microenvironment of multiple solid tumor types and may represent an interesting target for therapy, particularly in patients with sarcomas where LRRC15 is also expressed by malignant cells. ABBV-085 is a monomethyl auristatin-E antibody-drug conjugate that targets LRRC15 and showed antineoplastic efficacy in preclinical experiments. Herein, we report findings of ABBV-085 monotherapy or combination therapy in adult patients with sarcomas and other advanced solid tumors.

PATIENTS AND METHODS

This first-in-human phase I study (NCT02565758) assessed ABBV-085 safety, pharmacokinetics/pharmacodynamics, and preliminary antitumor activity. The study consisted of two parts: dose escalation and dose expansion. ABBV-085 was administered by intravenous infusion at 0.3 to 6.0 mg/kg every 14 days.

RESULTS

In total, 85 patients were enrolled; 45 patients received the recommended expansion dose of 3.6 mg/kg ABBV-085 monotherapy, including 10 with osteosarcoma and 10 with undifferentiated pleomorphic sarcoma (UPS). Most common treatment-related adverse events were fatigue, nausea, and decreased appetite. The overall response rate for patients with osteosarcoma/UPS treated at 3.6 mg/kg was 20%, including four confirmed partial responses. No monotherapy responses were observed for other advanced cancers treated at 3.6 mg/kg. One patient treated with ABBV-085 plus gemcitabine achieved partial response.

CONCLUSIONS

ABBV-085 appeared safe and tolerable at a dose of 3.6 mg/kg every 14 days, with preliminary antitumor activity noted in patients with osteosarcoma and UPS. Given the high unmet need in these orphan malignancies, further investigation into targeting LRRC15 in these sarcomas may be warranted.

Preliminary dose escalation results from a phase I/II, first-in-human study of MGC018 (anti-B7-H3 antibody-drug conjugate) in patients with advanced solid tumors

3071

Background: Antibody-drug conjugates (ADCs) are cancer agents that have a cytotoxic payload linked to a monoclonal antibody (mAb) that target cancer cells. ADCs offer increased cytotoxic activity while reducing normal tissue exposure. B7-H3 is expressed on multiple solid tumors with limited normal tissue expression. MGC018 is an investigational ADC with a duocarmycin payload linked to an anti-B7-H3 mAb. It is hypothesized that MGC018 has activity against B7-H3 expressing tumors with an acceptable safety profile. Methods: This study evaluates safety, dose-limiting toxicities (DLT), and maximum tolerated dose (MTD) of MGC018 in a dose escalation 3+3+3 design. In addition, pharmacokinetics, immunogenicity, and tumor response using RECIST v1.1 are evaluated. Cohort expansion will enroll at the MTD to assess safety and tumor response. Results: The study is enrolling Cohort 3 (6 total cohorts planned) in dose escalation. 20 patients (pts) were enrolled as of Feb 03, 2020. At least 1 treatment related adverse event (TRAE) occurred in 16 pts (80.0%). The most common TRAEs were neutropenia/decreased neutrophil count (35%); fatigue, lymphopenia/decreased lymphocyte count (30.0%); palmar plantar erythrodysaesthesia (PPE), skin hyperpigmentation (25.0%); pruritis, nausea, chills, infusion related reaction (20.0%); and vomiting, pyrexia, maculopapular rash (15.0%). Eleven pts (55.0%) experienced TRAEs ≥ Grade 3; events were decreased lymphocyte count/lymphopenia (n = 6), decreased neutrophil count/neutropenia (n = 3), PPE (n = 2), and maculopapular rash (n = 2). Three related serious adverse events occurred in 3 unique pts: pneumonitis in a pt with concurrent bacterial pneumonia, non-infectious gastroenteritis, and stasis dermatitis in a pt with chronic venous insufficiency. One DLT has occurred (Grade 4 neutropenia). No febrile neutropenia was observed. Target lesion decrease was noted in 1 pt each with small cell lung cancer (-6.3%), non-small cell lung cancer (-23.8%), and metastatic castrate-resistant prostate cancer (mCRPC) (-29.4%) with PSA change from 82.8 ng/ml to 57.1 ng/ml. One mCRPC pt with bone only disease had substantial improvement on bone scan and PSA decrease from 60 ng/ml to 4.7 ng/ml. Conclusions: Results to date demonstrate a manageable safety profile with early evidence of clinical activity. Continued dose escalation and clinical investigation of MGC018 is ongoing. Clinical trial information: NCT03729596 .

Safety and tolerability of MEDI0562 in combination with durvalumab or tremelimumab in patients with advanced solid tumors

3003

Background: We report safety and tolerability of MEDI0562, a humanized IgG1κ OX40 monoclonal antibody (mAb), in combination with durvalumab (durva; anti-PD-L1 mAb) or tremelimumab (treme; anti-CTLA-4 mAb) in patients (pts) with previously treated advanced solid tumors. Methods: In this phase 1, open-label study (NCT02705482), adult pts received escalating doses of MEDI0562 (2.25, 7.5 or 22.5 mg/kg) every 2 wks (Q2W) in combination with durva (1500 mg/kg) or treme (75 or 225 mg/kg) Q4W, until confirmed disease progression or unacceptable toxicity. Tumor assessments were performed Q8W with immune-related Response Evaluation Criteria in Solid Tumors. Results: In total, 27 and 31 pts received MEDI0562 + durva or treme, across 5 dose combination cohorts (3 + 3 design), with a maximum tolerated dose of 7.5 mg MEDI0652 + 1500 mg durva and maximum administered dose of 10 mg MEDI0562 + 225 mg treme. Median duration of exposure was 12.0 (range 2.0–80.9) and 8.0 (range 2.0–42.0) wks, respectively. Two (22.5 mg MEDI10562 + durva) and 3 (2.25 mg MEDI0652 + 225 mg treme, 22.5 mg MEDI0562 + 75 and 225 mg treme) dose limiting toxicities were observed. For MEDI0562 + durva and MEDI0562 + treme groups respectively, treatment-emergent adverse events (TEAEs) were reported in 96.3% and 100% of pts; most common TEAEs were fatigue (55.6%) and pruritus (45.2%), Gr 3/4 TEAEs occurred in 74.1% and 67.7%; and MEDI0562-related AEs were reported in 20 (74.1%) and 24 (77.4%) pts. Six TEAEs in each group led to MEDI0562 discontinuation (22.2% and 19.4%, respectively), 2 led to death (renal failure [7.5 mg MEDI0562 + durva], multiple organ dysfunction syndrome [22.5 mg MEDI0562 + 225 mg treme]). Three response evaluable pts had PR (11.5% [7.5 and 22.5 mg MEDI0562 + durva, n = 26]). Median overall survival was 17.4 and 11.9 mos for MEDI0562 + durva and MEDI0562 + treme, with stable disease seen in 9 pts from each group, 34.6% vs 29.0%, respectively. Serum exposure of MEDI0562 increased dose proportionally. Post treatment serum antidrug antibody (ADA) was detected in 20 pts from MEDI0562 + durva and MEDI0562 + treme (74.1% and 71.4%, respectively). The impact of ADA on MEDI0562 pharmacokinetics was seen at all doses. Mean percentage of Ki67+CD4+ and Ki67+CD8+ memory T cells increased, while mean percentage of OX40+CD4+ memory T cells decreased following the first dose of MEDI0562 + durva or treme. Conclusions: The safety profile of MEDI0562 in combination with durva or treme was similar between groups. Clinical activity was observed with MEDI0562 + durva in pts with advanced solid tumors. Clinical trial information: NCT02705482 .

Phase I/II dose-escalation and expansion study of FLX475 alone and in combination with pembrolizumab in advanced cancer

TPS3163

Background: Regulatory T cells (Treg) can dampen anti-tumor immune responses in the tumor microenvironment (TME). The predominant chemokine receptor on human Treg is CCR4, the receptor for the chemokines CCL17 and CCL22, which are produced by tumor cells, tumor-associated macrophages and dendritic cells, as well as by effector T cells (Teff) in the setting of an inflammatory anti-tumor response. Preclinical studies with orally-available CCR4 antagonists have demonstrated potent inhibition of Treg migration into tumors, an increase in the intratumoral Teff/Treg ratio, and anti-tumor efficacy as a single agent and in combination with checkpoint inhibitors. In a first-in-human trial conducted in healthy volunteers, the oral CCR4 antagonist FLX475 was demonstrated to be well tolerated with outstanding PK properties. A robust PD assay measuring receptor occupancy on circulating Treg demonstrated the ability to safely achieve exposure levels predicted to maximally inhibit Treg recruitment into tumors via CCR4 signaling. These human PK, PD, and safety data have enabled a streamlined design of a Phase 1/2 study of FLX475 in cancer patients both as monotherapy and in combination with checkpoint inhibitor. Methods: This clinical trial is a Phase 1/2, open-label, dose-escalation and cohort expansion study to determine the safety and preliminary anti-tumor activity of FLX475 as monotherapy and in combination with pembrolizumab. The study is being conducted in 2 parts, a dose-escalation phase (Part 1) and a cohort expansion phase (Part 2). In Part 1 (Phase 1) of the study, at least 3 to 6 eligible subjects are being enrolled in sequential cohorts treated with successively higher doses of FLX475 as monotherapy (Part 1a) or in combination with pembrolizumab (Part 1b). In Part 2 (Phase 2) of the study, expansion cohorts of both checkpoint-naïve and checkpoint-experienced patients with tumor types predicted to be enriched for Treg and/or CCR4 ligand expression (i.e. “charged tumors”) -- including both EBV+ and HPV+ tumors and NSCLC, HNSCC, and TNBC -- will be enrolled using a Simon 2-stage design. As of February 4, 2020, Phase 1 dose escalation has been completed and a recommended Phase 2 dose chosen for both FLX475 monotherapy and combination therapy with pembrolizumab. Enrollment into Phase 2 expansion cohorts has been initiated. Clinical trial information: NCT03674567 .

A phase I study of CD40 agonist ABBV-927 plus OX40 agonist ABBV-368 with or without the PD-1 inhibitor budigalimab in patients with advanced solid tumors

TPS3147

Background: CD40 is a key costimulatory molecule for both the innate and adaptive immune systems that is essential for T-cell activation and proliferation. OX40 is a costimulatory molecule that is involved in enhancing nascent immune responses and concomitantly acts to suppress regulatory T-cell activity. ABBV-927 and ABBV-368 are potent agonistic antibodies against CD40 and OX40, respectively. This open-label, Phase 1 study will evaluate the doublet combination of ABBV-927 and ABBV-368 and the triplet combination of ABBV-927, ABBV-368, and the programmed cell death protein-1 (PD-1) inhibitor budigalimab in patients with advanced solid tumors. Methods: For this study (NCT03893955), patients must be ≥18 y with an Eastern Cooperative Oncology Group performance status of 0-1. Patients must have an advanced solid tumor that has progressed on standard therapies. Disease-specific cohorts will include patients with non-small cell lung cancer (NSCLC) and triple-negative breast cancer (TNBC). Patients with NSCLC must have previously received a PD-1/PD-ligand 1 inhibitor and a platinum-based therapy and no more than one prior immunotherapy. Patients with TNBC must not have received immunotherapy. Patients with uncontrolled central nervous system metastases will be excluded. The recommended Phase 2 dose (RP2D) will first be identified with ABBV-927 + ABBV-368 in patients with solid tumors (Arm A) and will be expanded in disease-specific cohorts including TNBC. The RP2D of ABBV-927 + ABBV-368 + budigalimab will be identified in patients with NSCLC (Arm B). The primary endpoints are determination of the RP2D of ABBV-927 + ABBV-368, the RP2D of ABBV-927 + ABBV-368 + budigalimab, and overall response rate; duration of response, progression-free survival, safety, and pharmacokinetics are secondary endpoints. Screening began on 21 May 2019, and enrollment is ongoing. Clinical trial information: NCT03893955 .

Efficacy and Safety of Avelumab Treatment in Patients With Advanced Unresectable Mesothelioma: Phase 1b Results From the JAVELIN Solid Tumor Trial

Importance

Patients with malignant mesothelioma whose disease has progressed after platinum and pemetrexed treatment have limited options. Anti-programmed cell death 1 (PD-1) antibodies have antitumor activity in this disease, but little is known about the activity of anti-programmed cell death ligand 1 (PD-L1) antibodies in patients with mesothelioma.

Objective

To assess the efficacy and safety of avelumab in a cohort of patients with previously treated mesothelioma.

Design, Setting, and Participants

Phase 1b open-label study (JAVELIN Solid Tumor) in patients with unresectable mesothelioma that progressed after platinum and pemetrexed treatment, enrolled at 25 sites in 3 countries between September 9, 2014, and July 22, 2015.

Interventions

Participants received avelumab, 10 mg/kg, every 2 weeks until disease progression, unacceptable toxic effects, or withdrawal from the study.

Main Outcomes and Measures

Prespecified end points included confirmed best overall response based on Response Evaluation Criteria In Solid Tumors, version 1.1; duration of response; progression-free survival (PFS); overall survival (OS); PD-L1 expression-based analyses; and safety.

Results

Of 53 patients treated with avelumab, the median age was 67 (range, 32-84) years; 32 (60%) were male. As of December 31, 2016, median follow-up was 24.8 (range, 16.8-27.8) months. Twenty patients (38%) had 3 or more previous lines of therapy (median, 2; range, 1-8). The confirmed objective response rate (ORR) was 9% (5 patients; 95% CI, 3.1%-20.7%), with complete response in 1 patient and partial response in 4 patients. Responses were durable (median, 15.2 months; 95% CI, 11.1 to not estimable months) and occurred in patients with PD-L1-positive tumors (3 of 16; ORR, 19%; 95% CI, 4.0%-45.6%) and PD-L1-negative tumors (2 of 27; ORR, 7%; 95% CI, 0.9%-24.3%) based on a 5% or greater PD-L1 cutoff. Disease control rate was 58% (31 patients). Median PFS was 4.1 (95% CI, 1.4-6.2) months, and the 12-month PFS rate was 17.4% (95% CI, 7.7%-30.4%). Median OS was 10.7 (95% CI, 6.4-20.2) months, and the median 12-month OS rate was 43.8% (95% CI, 29.8%-57.0%). Five patients (9%) had a grade 3 or 4 treatment-related adverse event, and 3 (6%) had a grade 3 or 4 immune-related, treatment-related adverse event. There were no treatment-related deaths.

Conclusions and Relevance

Avelumab showed durable antitumor activity and disease control with an acceptable safety profile in a heavily pretreated cohort of patients with mesothelioma.

Trial Registration

ClinicalTrials.gov identifier: NCT01772004.

Adenosine 2A Receptor Blockade as an Immunotherapy for Treatment-Refractory Renal Cell Cancer

Adenosine mediates immunosuppression within the tumor microenvironment through triggering adenosine 2A receptors (A2AR) on immune cells. To determine whether this pathway could be targeted as an immunotherapy, we performed a phase I clinical trial with a small-molecule A2AR antagonist. We find that this molecule can safely block adenosine signaling in vivo. In a cohort of 68 patients with renal cell cancer (RCC), we also observe clinical responses alone and in combination with an anti-PD-L1 antibody, including subjects who had progressed on PD-1/PD-L1 inhibitors. Durable clinical benefit is associated with increased recruitment of CD8⁺ T cells into the tumor. Treatment can also broaden the circulating T-cell repertoire. Clinical responses are associated with an adenosine-regulated gene-expression signature in pretreatment tumor biopsies. A2AR signaling, therefore, represents a targetable immune checkpoint distinct from PD-1/PD-L1 that restricts antitumor immunity. SIGNIFICANCE: This first-in-human study of an A2AR antagonist for cancer treatment establishes the safety and feasibility of targeting this pathway by demonstrating antitumor activity with single-agent and anti-PD-L1 combination therapy in patients with refractory RCC. Responding patients possess an adenosine-regulated gene-expression signature in pretreatment tumor biopsies.See related commentary by Sitkovsky, p. 16.This article is highlighted in the In This Issue feature, p. 1.

Five-Year Survival and Correlates Among Patients With Advanced Melanoma, Renal Cell Carcinoma, or Non-Small Cell Lung Cancer Treated With Nivolumab

IMPORTANCE

Nivolumab, a monoclonal antibody that inhibits programmed cell death 1, is approved by the US Food and Drug Administration for treating advanced melanoma, renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), and other malignancies. Data on long-term survival among patients receiving nivolumab are limited.

OBJECTIVES

To analyze long-term overall survival (OS) among patients receiving nivolumab and identify clinical and laboratory measures associated with tumor regression and OS.

DESIGN, SETTING, AND PARTICIPANTS

This was a secondary analysis of the phase 1 CA209-003 trial (with expansion cohorts), which was conducted at 13 US medical centers and included 270 patients with advanced melanoma, RCC, or NSCLC who received nivolumab and were enrolled between October 30, 2008, and December 28, 2011. The analyses were either specified in the original protocol or included in subsequent protocol amendments that were implemented between 2008 and 2012. Statistical analysis was performed from October 30, 2008, to November 11, 2016.

INTERVENTION

In the CA209-003 trial, patients received nivolumab (0.1-10.0 mg/kg) every 2 weeks in 8-week cycles for up to 96 weeks, unless they developed progressive disease, achieved a complete response, experienced unacceptable toxic effects, or withdrew consent.

MAIN OUTCOMES AND MEASURES

Safety and activity of nivolumab; OS was a post hoc end point with a minimum follow-up of 58.3 months.

RESULTS

Of 270 patients included in this analysis, 107 (39.6%) had melanoma (72 [67.3%] male; median age, 61 [range, 29-85] years), 34 (12.6%) had RCC (26 [76.5%] male; median age, 58 [range, 35-74] years), and 129 (47.8%) had NSCLC (79 [61.2%] male; median age, 65 [range, 38-85] years). Overall survival curves showed estimated 5-year rates of 34.2% among patients with melanoma, 27.7% among patients with RCC, and 15.6% among patients with NSCLC. In a multivariable analysis, the presence of liver (odds ratio [OR], 0.31; 95% CI, 0.12-0.83; P = .02) or bone metastases (OR, 0.31; 95% CI, 0.10-0.93; P = .04) was independently associated with reduced likelihood of survival at 5 years, whereas an Eastern Cooperative Oncology Group performance status of 0 (OR, 2.74; 95% CI, 1.43-5.27; P = .003) was independently associated with an increased likelihood of 5-year survival. Overall survival was significantly longer among patients with treatment-related AEs of any grade (median, 19.8 months; 95% CI, 13.8-26.9 months) or grade 3 or more (median, 20.3 months; 95% CI, 12.5-44.9 months) compared with those without treatment-related AEs (median, 5.8 months; 95% CI, 4.6-7.8 months) (P < .001 for both comparisons based on hazard ratios).

CONCLUSIONS AND RELEVANCE

Nivolumab treatment was associated with long-term survival in a subset of heavily pretreated patients with advanced melanoma, RCC, or NSCLC. Characterizing factors associated with long-term survival may inform treatment approaches and strategies for future clinical trial development.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00730639.

Immunobiology, preliminary safety, and efficacy of CPI-006, an anti-CD73 antibody with immune modulating activity, in a phase 1 trial in advanced cancers

2505

Background: CPI-006 inhibits CD73, a nucelotidase that converts AMP to adenosine and functions as a lymphocyte adhesion molecule. CPI-006 is a humanized IgG1 FcγR binding-deficient antibody that binds to CD73+ T and B lymphocytes leading to activation of B cells and expression of CD69. This study investigates the immunobiology, safety, and efficacy of CPI-006 monotherapy and in combination with CPI-444, an adenosine A2A receptor (A2AR) antagonist (NCT03454451). Methods: Patients with relapsed solid tumors were treated in a 3 + 3 escalation study with 1, 3, 6 or 12 mg/kg CPI-006 (Q3w IV infusion) monotherapy or in combination with CPI-444 (100 mg, PO, BID). Flow cytometry was performed on blood samples for lymphocyte subset analysis and receptor occupancy. Results: 17 patients were enrolled; 11 monotherapy and 6 combination. CPI-006 was associated with Grade 1 infusion reactions occuring within 30 minutes of the first infusion and were eliminated by premedication with non-steroidals. No DLTs with monotherapy or combination therapy were seen. Receptor occupancy on peripheral lymphocytes was maintained for the full dosing interval at 12 mg/kg. Pharmacodynamic effects suggesting immune modulation were observed within 1 hr of infusion at all dose levels and included a decrease in peripheral blood CD73pos B cells (mean reduction 86%, p < 0.05), increased CD73neg CD4 T cells (mean increase 37%, p < 0.01), and decreased CD8 T cells (mean reduction 20%, p < 0.01) compared to baseline. Overall, CD4:CD8 ratios were increased. Tumor regression was observed in a prostate cancer patient after 5 cycles of monotherapy at 6 mg/kg; peripheral B cells partially returned by the second cycle and reached a new homeostatic level through subsequent cycles. No change in serum immunoglobulins were observed. Conclusions: CPI-006 induces a rapid lymphocyte redistribution, including a transient reduction of circulating CD73pos B cells suggesting redistribution to lymphoid tissues, and an increased CD4:CD8 ratio, consistent with increased TH effector/memory cells in the blood. The treatment has been well-tolerated, and there is early evidence of anti-tumor activity of CPI-006 monotherapy. Clinical trial information: NCT03454451.

First-in-human phase 1 study of ABBV-085, an antibody-drug conjugate (ADC) targeting LRRC15, in sarcomas and other advanced solid tumors

3004

Background: ABBV-085 is an ADC (conjugated to monomethyl auristatin E, drug:antibody ratio of 2:1) directed against leucine-rich repeat containing 15 (LRRC15), a type 1 transmembrane protein highly expressed on the surface of sarcomas and cancer-associated fibroblasts in stroma of many other cancers. ABBV-085 induced antitumor activity in both in vitro and xenograft models of sarcoma. This phase 1, first-in-human, 2-part study assessed the safety/tolerability of ABBV-085 in patients (pts) with advanced solid tumors (NCT02565758). Methods: Eligible pts (≥18 yr; advanced solid tumors) received ABBV-085 intravenously in a 3+3 dose-escalation (DE) design; 0.3- to 4.8-mg/kg doses every 2 wk (8 cohorts). Pharmacokinetics (PK) were assessed in cycle 1 and cycle 3. Results: As of Dec 2018, 78 pts were enrolled in monotherapy DE and dose-expansion (EXP) cohorts (≤2.7 mg/kg, n = 21; 3.6 mg/kg, n = 45; 4.2 mg/kg, n = 6; 4.8 mg/kg, n = 6); median age: 58 yr (range 21–84); median treatment (Tx) duration: 6.2 wk (range 0.3–54.4). Overall, 77 (98.7%) pts reported ≥1 Tx-emergent adverse events (TEAEs). Fatigue (48.7%) was most common; 19 (24.4%) pts reported grade 1/2 blurred vision (reversible on study discontinuation). Grade ≥3 TEAEs were reported in 56 (71.8%) pts; anemia (14.1%) was the most common. Dose-limiting toxicities occurred at 3.6 mg/kg (n = 1; anemia), 4.2 mg/kg (n = 1; hypertriglyceridemia), and 4.8 mg/kg (n = 2; ileus and nausea); 3.6 mg/kg was chosen as the recommended phase 1b dose (RP1bD). PK exhibited dose-proportional increase in the area under the curve after single-dose administration; half-life was 2.84 days at the RP1bD. Of the 27 sarcoma pts (DE [n = 8]/EXP [n = 19] cohorts; undifferentiated pleomorphic sarcoma [n = 10], osteosarcoma [n = 10], and other sarcomas [n = 7]) treated at the RP1bD, 4 (14.8%) had confirmed partial response (PR; 2 [7.4%] unconfirmed), 8 (29.6%) had stable disease, 11 (40.7%) had progressive disease; 2 (7.4%) were not evaluable. The median duration of response (confirmed responders) was 7.6 mo (95% CI: 5.6–9.2). Updated safety and efficacy data will be reported. Conclusions: ABBV-085 was well tolerated with durable PR observed in pts with advanced sarcomas. Clinical trial information: NCT02565758.

Phase 1/1b multicenter trial of TPST-1120, a peroxisome proliferator-activated receptor alpha (PPARα) antagonist as a single agent (SA) or in combination in patients with advanced solid tumors

TPS2665

Background: Tumor cells initially favor glucose metabolism via aerobic glycolysis. As tumors rapidly proliferate and metastasize, glucose stores are depleted and facilitated by a hypoxic tumor microenvironment (TME) and metabolic reprogramming shifts intracellular metabolism(IcM) towards fatty acid oxidation (FAO). Fatty acids support metabolism of suppressive immune cells in the TME in addition to tumor growth. PPARα is a ligand-activated nuclear transcription factor which regulates lipid metabolism and FAO. TPST-1120 is a first in class, oral selective PPARα antagonist that blocks transcription of PPARα target genes leading to an intracellular metabolism shift from FAO to glycolysis. Reduction of fatty acids in the TME leads to direct killing of tumor cells dependent on FAO, skews macrophages from immune suppressive M2 phenotype to an effector M1 phenotype and facilitates the cytotoxicity of immune effector cells. TPST-1120 also restores thrombospondin-1, a known natural inhibitor of angiogenesis, to homeostatic levels within the TME. TPST-1120 has an IC50 of 0.04 nM with > 35 fold selectivity over other PPAR isoforms. Preclinical studies in multiple tumor models show efficacy of TPST-1120 as a SA and in combination(combo) with an anti-PD1 monoclonal antibody (mAb) and chemotherapy. Methods: We have initiated a phase 1/1b multicenter, open label Dose Escalation (DEs) and Dose Expansion (DEx) trial to evaluate TPST-1120 as a SA and in combo with nivolumab, an anti-PD1 mAb; docetaxel, a chemotherapeutic agent and cetuximab, an anti-EGFR mAb. Objectives: 1) evaluate safety and tolerability of continuous dosing of TPST-1120 2) identify a recommended phase 2 dose (RP2D) and 3) evaluate efficacy. Eligibility: 1) patients with select advanced solid tumors who have failed 1 and up to 5 prior therapies. This phase 1/1b adaptive design has 4 DEs arms, 1 SA arm and 3 combination arms in which TPST-1120 is combined with nivolumab, docetaxel or cetuximab. The RP2D of TPST-1120 to proceed to DEx will be determined by safety and biomarkers during DEs. The DEx arms have 8 histology-specific cohorts, 4 SA arms and 4 combo arms and will follow a 2-stage expansion design. Biomarker analyses include gene expression profiling of PPARα-associated genes, tumor markers of immune modulation and serum lipid profiling. The total sample size is up to 338 pts. This trial is accruing at U.S sites. Clinical trial information: NCT03829436.

A phase I/Ib multicenter study to evaluate the humanized anti-CD73 antibody, CPI-006, as a single agent, in combination with CPI-444, and in combination with pembrolizumab in adult patients with advanced cancers

TPS2646

Background: CD73 expression is elevated in tumors and contributes to increasing levels of immunosuppressive adenosine in the tumor microenvironment. CD73 knockout mice exhibit reduced tumor growth and resistance to experimental metastasis. Inhibition of CD73 activity with an anti-CD73 antibody blocks adenosine production, shown to inhibit tumor growth in syngeneic models. CPI-006 is a humanized IgG1 FcγR binding-deficient anti-CD73 antibody now being investigated in this Phase 1/1b multicenter, open label trial as single agent (SA) or combination with CPI-444, an oral, small molecule, selective A2aR antagonist or in combination with pembrolizumab, an anti-PD1 indicated for the treatment of patients across a number of malignancies (NCT03454451). Methods: Up to 462 subjects will be enrolled at approximately 35 sites in the US, Canada and Australia. Eligible patients must have: non-small cell lung, renal cell carcinoma, urothelial bladder, cervical, colorectal, ovarian, pancreatic, prostate, head and neck, triple-negative breast, endometrial, select sarcomas and non-Hodgkin lymphoma malignancies relapsed, refractory or intolerant to 1 to 5 standard therapies; aged ≥ 18 yo; adequate organ function and measurable disease. The objectives of the study are 1) evaluate the safety and tolerability of SA CPI-006, in combination with CPI-444 and in combination with pembrolizumab, 2) evaluate the pharmacokinetics of each regimen and 3) identify potential biomarker signals predictive of response. Study design in table. Study Design. Clinical trial information: NCT03454451. [Table: see text]

AB928, a novel dual adenosine receptor antagonist, combined with chemotherapy or AB122 (anti-PD-1) in patients (pts) with advanced tumors: Preliminary results from ongoing phase I studies

2604

Background: AB928, a selective, small-molecule A2aR/A2bR antagonist, potently blocks the immunosuppressive effects of high adenosine concentrations in the tumor microenvironment. Preclinically, combining adenosine receptor inhibition with either chemotherapy or anti-PD-1 resulted in greater tumor control, suggesting AB928 may have additive activity when paired with either of these agents in cancer pts. Methods: Three dose-escalation (3+3 design) studies are assessing the safety, pharmacokinetics (PK), pharmacodynamics, and clinical activity of increasing doses of AB928 (75, 150, 200 mg orally once daily) in combination with: standard pegylated liposomal doxorubicin in triple-negative breast cancer (TNBC) and ovarian cancer (OC); standard mFOLFOX6 in gastroesophageal cancer (GEC) and colorectal cancer (CRC); and AB122 (240 mg every 2 weeks) in various advanced tumors. Following identification of the recommended phase 2 dose of AB928 in combination with chemotherapy or AB122 in dose escalation, the following tumor cohorts may be expanded (15-40 pts/cohort) to further test the combinations: TNBC and OC, GEC and CRC, and renal cell carcinoma. Results: As of 01Feb2019, 9 pts were treated across the 3 studies, and time on treatment ranged from 1-182 days (table). Overall, AB928 combination therapy was well tolerated. Two pts underwent post-baseline disease assessment; both had stable disease. Preliminary data indicate that AB928 PK and adenosine receptor coverage in cancer pts are similar to what was previously assessed in healthy volunteers. AB122 PK and PD-1 coverage are equally unaffected by AB928 co-administration. Updated data, including biomarker data, will be presented at the meeting. Conclusions: Early results showed a favorable safety profile of AB928 combination therapy. All 3 studies are actively recruiting pts. Clinical trial information: NCT03719326; NCT03720678; NCT03629756. [Table: see text]

Avelumab in patients with previously treated mesothelioma: Updated phase 1b results from the JAVELIN Solid Tumor trial

166

Background: Avelumab, a human anti-PD-L1 IgG1 monoclonal antibody, is approved for treatment of metastatic Merkel cell carcinoma (US and EU) and advanced urothelial carcinoma progressed on platinum therapy (US). Here, we report updated phase 1b data for avelumab in patients (pts) with previously treated mesothelioma. Methods: Pts with unresectable pleural or peritoneal mesothelioma whose disease had progressed after platinum and pemetrexed therapy received avelumab 10 mg/kg IV Q2W until progression, unacceptable toxicity, or withdrawal. Tumors were assessed every 6 wks (RECIST 1.1). Endpoints included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and adverse events (AEs; NCI CTCAE v4.0). Results: As of Dec 31, 2016, 53 pts were treated and followed for a median of 24.8 mos (range 16.8–27.8). Median age was 67 y (range 32–84). Pts had received a median of 2 prior lines of therapy (range 1–8). Confirmed ORR was 9.4% (95% CI 3.1–20.7; complete response in 1.9%, partial response in 7.5%). In pts with 1 (n = 18), 2 (n = 15) or ≥3 (n = 20) prior lines of therapy, ORR was 5.6%, 13.3% and 10.0% respectively. Median duration of response was 15.2 mos (95% CI 11.1–not estimable). 26 pts (49.1%) had stable disease as best response and the disease control rate was 58.5%. Median PFS was 4.1 mos (95% CI 1.4–6.2) and the 6-mo PFS rate was 38.0% (95% CI 24.2–51.7). Median OS was 10.9 mos (95% CI 7.5–21.0) and the 12-mo OS rate was 45.9% (95% CI 31.9–58.8). In evaluable pts with PD-L1+ (n = 16) and PD-L1− (n = 27) tumors (≥5% tumor cell cutoff), ORR was 18.8% (95% CI 4.0–45.6) and 7.4% (95% CI 0.9–24.3), and the 6-mo PFS rate was 37.5% (95% CI 14.1–61.2) and 42.0% (95% CI 23.1–59.8). 43 pts (81.1%) had a treatment-related (TR)AE, most commonly ( > 10%) infusion-related reaction (35.8%; all grade 1/2), chills (15.1%), fatigue (15.1%) and pyrexia (11.3%). 5 pts (9.4%) had a grade ≥3 TRAE. 14 pts (26.4%) had an immune-related AE, which was grade ≥3 in 3 pts (5.7%; pneumonitis, colitis, and type 1 diabetes mellitus). No treatment-related deaths occurred. Conclusions: Avelumab showed clinical activity and acceptable safety in pts with previously treated mesothelioma. Clinical trial information: NCT01772004.

Atezolizumab (atezo) plus platinum-based chemotherapy (chemo) in non-small cell lung cancer (NSCLC): Update from a phase Ib study

9092

Background: Platinum-based chemo is a standard first-line (1L) therapy for NSCLC lacking actionable gene alterations. Preclinical evidence suggests that chemo can play an immunomodulatory role and induce tumor antigen release, supporting combining chemo with immunotherapy. Atezo is a humanized and Fc-region-modified monoclonal anti-programmed death-ligand-1 (PD-L1) antibody that blocks interaction with PD1 or B7.1. The GP28328 study (NCT01633970) assessed safety and efficacy of atezo plus 1L chemo regimens in multiple tumor types. Methods: In this multicenter, multi-arm study, patients (pts) with locally advanced or metastatic NSCLC with no prior chemo for advanced disease received 15 mg/kg atezo IV q3w with standard doses of chemo (Arm C: carboplatin [carbo]+paclitaxel q3w; Arm D: carbo+pemetrexed q3w; Arm E: carbo+nab-paclitaxel qw) all for ≤6 cycles followed by atezo maintenance until loss of clinical benefit (+ pemetrexed maintenance until progression, Arm D). The primary endpoint was safety; secondary endpoints were overall response rate (ORR), PFS, and OS. Results: By the 30 Aug 2016 cut-off, 76 NSCLC pts were evaluable (n = 25, 25, 26 for Arms C, D, E, respectively). At this cut-off, the most common treatment-related grade 3–4 adverse events (AEs) were neutropenia (36% C, 36% D, 42% E) and anemia (16% C, 16% D, 31% E). Three potentially related grade 5 AEs were seen (arm C: pneumonia; arm D: systemic candida; arm E: autoimmune hepatitis). Confirmed ORRs were 36%, 64%, 46% for Arms C, D (1 CR), and E (4 CR). Median PFS (95% CI) was 7.1 months (4.2–8.3) for C, 8.4 months (4.7–11) for D, and 5.7 months (4.4–14.8) for E. Median OS (95% CI) was 12.9 months (8.8–not evaluable) for C, 19.3 months (14.7–27.4) for D, and 14.8 months (12.7–not evaluable) for E. Conclusions: Atezo was well tolerated when combined with various chemo regimens for advanced NSCLC. Clinical activity in terms of ORR was favorable supporting potential synergy between atezo and chemo. PFS and OS data show promising benefits, but are limited by small numbers and wide confidence intervals. Phase III studies that include chemotherapy and atezolizumab are currently ongoing. Clinical trial information: NCT01633970.

A phase 1 study to evaluate the safety, pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity of the OX40 agonist MEDI0562 in combination with tremelimumab or durvalumab in adult aubjects with advanced solid tumors

TPS3100

Background: Recent advances in treatment of solid tumors include single or combined use of monoclonal antibodies (mAbs) against the immune checkpoints CTLA-4 or PD-1/PD-L1 that can reactivate antitumor cytotoxic tumor-infiltrating lymphocytes (TILs) and significantly improve OS (Menon S, et al. Cancers (Basel). 2016;8:E106.) (Antonia S, et al. Lancet Oncol. 2016; 17:299-308). Activation of TILs via the costimulatory OX40 (CD134) molecule, may offer an alternative and non-redundant pathway for increasing antitumor immunity. OX40 costimulation promotes effector T cell expansion and longevity, overcomes regulatory T cell suppression and provides survival benefit in animal models of tumor challenge (Linch SN, et al. Front Oncol. 2015;5:34). MEDI0562 is an investigational, humanized IgG1κ anti-OX40 mAb that triggers OX40 signaling. Coadministration of an OX40 agonist and either a CTLA-4 or PD-1/PD-L1 pathway inhibitor may promote synergistic effects against certain solid tumors and may be tolerable administered in combination. Methods: A Phase 1, multicenter, open-label study (NCT02705482) is underway to evaluate safety (primary endpoint), pharmacokinetics, pharmacodynamics, immunogenicity and antitumor activity (secondary endpoints) of MEDI0562 in combination with either anti-PD-L1 mAb durvalumab or anti-CTLA-4 mAb tremelimumab in adult subjects with previously treated advanced solid tumors. Subjects with primary CNS tumors and hematologic malignancies are excluded. The study includes a dose escalation and expansion phase, with 2 treatment arms in each: MEDI0562/durvalumab combination (Arm A) and MEDI0562/tremelimumab combination (Arm B). Safety assessments include AEs, serious AEs, dose-limiting toxicities, abnormal laboratory parameters, vital signs, and electrocardiogram results. Antitumor efficacy will be assessed as OR, disease control, duration of response, PFS, and OS using RECIST Version 1.1. Subjects will remain on treatment until unacceptable toxicity, progressive disease or other reasons for discontinuation. Clinical trial information: NCT02705482.

Safety and clinical activity of adenosine A2a receptor (A2aR) antagonist, CPI-444, in anti-PD1/PDL1 treatment-refractory renal cell (RCC) and non-small cell lung cancer (NSCLC) patients

3004

Background: Adenosine production in the tumor leads to immunosuppression through A2aR on infiltrating immune cells. CPI-444 is an oral A2aR antagonist with single agent(SA) anti-tumor activity in pre-clinical models. This phase 1/1b clinical trial uses a 2-step adaptive design to evaluate CPI-444 as a SA and in combination (combo) with the anti-PDL1 antibody, atezolizumab (atezo). We report results of RCC and NSCLC cohorts. Methods: Primary objectives: safety, efficacy and to identify optimal dose/schedule. Step 1 utilized 3 SA and 1 combo cohort to select dose/schedule. Step 2 included disease-specific expansion cohorts including RCC and NSCLC. Eligible pts had selected advanced cancers and failed standard therapies including checkpoint inhibitors. Results: 34 pts have enrolled and 25 pts were evaluable for response (Table 1). Median prior regimens: 3 (range,1-5) and most pts were resistant/refractory to anti PD1/PDL1 therapy (R/R). Most common AEs were Gr 1 nausea (n = 3) and pyrexia (n = 3); Gr 3 tachycardia was the only possibly related SAE. The selected Step 2 doses were CPI-444 100mg BID as a SA and in combo with atezo 840mg IV q2 weeks. The disease control rate (DCR, CR+PR+SD; duration 2 mo to > 8 mo) for pts with RCC and NSCLC cohorts were 86% and 50%, (100% and 43% for R/R pts), respectively. DCRs were similar in the SA and combo cohorts. Of 7 evaluable RCC pts, 1 pt has an ongoing PR (SA cohort, > 4 mo) and 5 have ongoing SD, duration 3 mo to > 8 mo (2 SA, 3 combo). Biopsy of the PR pt showed no detectable tumor and infiltration with CD8+ lymphocytes. In 18 evaluable NSCLC pts, 1 PR (PDL1 negative pt) and 8 SD were seen. PRs and SDs were seen in R/R pts and in PDL1 negative pts in both diseases. Conclusions: CPI-444 is well tolerated and shows anti-tumor activity in RCC and NSCLC pts as a SA and in combo. Pts who are R/R to anti PD1/PDL1 therapy and who are PDL1 negative can also benefit. Clinical trial information: NCT02655822. [Table: see text]

Phase 1 trial of CA-170, a novel oral small molecule dual inhibitor of immune checkpoints PD-1 and VISTA, in patients (pts) with advanced solid tumor or lymphomas

TPS3099

Background: Programmed-death 1 (PD-1) and V-domain Ig suppressor of T-cell activation (VISTA) are independent immune checkpoints that negatively regulate T-cell function and are implicated in various malignancies. Preclinical studies have demonstrated that dual blockade of these pathways is synergistic. CA-170 is a first-in-class oral small molecule that directly targets both PD-1/PD-L1 and VISTA pathways and has shown anti-tumor activity in multiple preclinical models. Methods: The dose escalation phase has a target enrollment of 50 pts with advanced solid tumors or lymphomas onto escalating doses; the first four single-pt cohorts are accelerated titration but then switch to 3+3 design. The dose expansion phase has a target enrollment of 250 pts with select tumor types known to be responsive to anti-PD-1/L1 inhibitors and/or known to express PD-L1 or VISTA. Key eligibility criteria include: age ≥ 18 years, ECOG ≤1, adequate organ function, and ineligible for/did not respond to standard therapy including anti-PD-1/L1 inhibitors, where available. Primary objectives of this first-in-human study: safety, maximum tolerated dose, and recommended phase 2 dose. Secondary objectives: pharmacokinetics (PK) and anti-tumor activity. Exploratory endpoints: biomarkers and pharmacodynamic (PD) effects, which include changes in immune cell and peripheral cytokine populations in tumor (IHC/mRNA) and blood (flow cytometry/mRNA). Oral CA-170 is administered once daily in 21-day cycles. Response will be evaluated every other cycle per RECIST (v1.1) and Immune-related Response Criteria or by Cheson criteria (2007). Patients who discontinue treatment for reasons other than progressive disease will be followed for progression-free survival. Serial plasma, blood, and tumor samples will be collected for PK and PD evaluation. Clinical trial identifier: Clinical trial information: NCT02812875.

Atezolizumab, an Anti-Programmed Death-Ligand 1 Antibody, in Metastatic Renal Cell Carcinoma: Long-Term Safety, Clinical Activity, and Immune Correlates From a Phase Ia Study

PURPOSE

The objective was to determine the safety and clinical activity of atezolizumab (MPDL3280A), a humanized programmed death-ligand 1 (PD-L1) antibody, in renal cell carcinoma (RCC). Exploratory biomarkers were analyzed and associated with outcomes.

PATIENTS AND METHODS

Seventy patients with metastatic RCC, including clear cell (ccRCC; n = 63) and non-clear cell (ncc; n = 7) histologies, received atezolizumab intravenously every 3 weeks. PD-L1 expression was scored at four diagnostic levels (0/1/2/3) that were based on PD-L1 staining on tumor cells and tumor-infiltrating immune cells (IC) with the SP142 assay. Primary end points were safety and toxicity; secondary end points assessed clinical activity per Response Evaluation Criteria in Solid Tumors version 1.1 and immune-related response criteria. Plasma and tissue were analyzed for potential biomarkers of atezolizumab response.

RESULTS

Grade 3 treatment-related and immune-mediated adverse events occurred in 17% and 4% of patients, respectively, and there were no grade 4 or 5 events. Sixty-three patients with ccRCC were evaluable for overall survival (median, 28.9 months; 95% CI, 20.0 months to not reached) and progression-free survival (median, 5.6 months; 95% CI, 3.9 to 8.2 months), and 62 patients were evaluable for objective response rate (ORR; 15%; 95% CI, 7% to 26%). ORR was evaluated on the basis of PD-L1 IC expression (IC1/2/3: n = 33; 18%; 95% CI, 7% to 35%; and IC0: n = 22; 9%; 95% CI, 1% to 29%). The ORR for patients with Fuhrman grade 4 and/or sarcomatoid histology was 22% (n = 18; 95% CI, 6% to 48%). Decreases in circulating plasma markers and acute-phase proteins and an increased baseline effector T-cell-to-regulatory T-cell gene expression ratio correlated with response to atezolizumab.

CONCLUSION

Atezolizumab demonstrated a manageable safety profile and promising antitumor activity in patients with metastatic RCC. Correlative studies identified potential predictive and pharmacodynamic biomarkers. These results have guided ongoing studies and combinations with atezolizumab in RCC.

Overall Survival and Long-Term Safety of Nivolumab (Anti-Programmed Death 1 Antibody, BMS-936558, ONO-4538) in Patients With Previously Treated Advanced Non-Small-Cell Lung Cancer

PURPOSE

Programmed death 1 is an immune checkpoint that suppresses antitumor immunity. Nivolumab, a fully human immunoglobulin G4 programmed death 1 immune checkpoint inhibitor antibody, was active and generally well tolerated in patients with advanced solid tumors treated in a phase I trial with expansion cohorts. We report overall survival (OS), response durability, and long-term safety in patients with non-small-cell lung cancer (NSCLC) receiving nivolumab in this trial.

PATIENTS AND METHODS

Patients (N = 129) with heavily pretreated advanced NSCLC received nivolumab 1, 3, or 10 mg/kg intravenously once every 2 weeks in 8-week cycles for up to 96 weeks. Tumor burden was assessed by RECIST (version 1.0) after each cycle.

RESULTS

Median OS across doses was 9.9 months; 1-, 2-, and 3-year OS rates were 42%, 24%, and 18%, respectively, across doses and 56%, 42%, and 27%, respectively, at the 3-mg/kg dose (n = 37) chosen for further clinical development. Among 22 patients (17%) with objective responses, estimated median response duration was 17.0 months. An additional six patients (5%) had unconventional immune-pattern responses. Response rates were similar in squamous and nonsquamous NSCLC. Eighteen responding patients discontinued nivolumab for reasons other than progressive disease; nine (50%) of those had responses lasting > 9 months after their last dose. Grade 3 to 4 treatment-related adverse events occurred in 14% of patients. Three treatment-related deaths (2% of patients) occurred, each associated with pneumonitis.

CONCLUSION

Nivolumab monotherapy produced durable responses and encouraging survival rates in patients with heavily pretreated NSCLC. Randomized clinical trials with nivolumab in advanced NSCLC are ongoing.

Survival, Durable Response, and Long-Term Safety in Patients With Previously Treated Advanced Renal Cell Carcinoma Receiving Nivolumab

PURPOSE

Blockade of the programmed death-1 inhibitory cell-surface molecule on immune cells using the fully human immunoglobulin G4 antibody nivolumab mediates tumor regression in a portion of patients with advanced treatment-refractory solid tumors. We report clinical activity, survival, and long-term safety in patients with advanced renal cell carcinoma (RCC) treated with nivolumab in a phase I study with expansion cohorts.

PATIENTS AND METHODS

A total of 34 patients with previously treated advanced RCC, enrolled between 2008 and 2012, received intravenous nivolumab (1 or 10 mg/kg) in an outpatient setting once every two weeks for up to 96 weeks and were observed for survival and duration of response after treatment discontinuation.

RESULTS

Ten patients (29%) achieved objective responses (according to RECIST [version 1.0]), with median response duration of 12.9 months; nine additional patients (27%) demonstrated stable disease lasting > 24 weeks. Three of five patients who stopped treatment while in response continued to respond for ≥ 45 weeks. Median overall survival in all patients (71% with two to five prior systemic therapies) was 22.4 months; 1-, 2-, and 3-year survival rates were 71%, 48%, and 44%, respectively. Grade 3 to 4 treatment-related adverse events occurred in 18% of patients; all were reversible.

CONCLUSION

Patients with advanced treatment-refractory RCC treated with nivolumab demonstrated durable responses that in some responders persisted after drug discontinuation. Overall survival is encouraging, and toxicities were generally manageable. Ongoing randomized clinical trials will further assess the impact of nivolumab on overall survival in patients with advanced RCC.