Society for Immunotherapy of Cancer (SITC) recommendations on intratumoral immunotherapy clinical trials (IICT): from premalignant to metastatic disease

BACKGROUND

Intratumorally delivered immunotherapies have the potential to favorably alter the local tumor microenvironment and may stimulate systemic host immunity, offering an alternative or adjunct to other local and systemic treatments. Despite their potential, these therapies have had limited success in late-phase trials for advanced cancer resulting in few formal approvals. The Society for Immunotherapy of Cancer (SITC) convened a panel of experts to determine how to design clinical trials with the greatest chance of demonstrating the benefits of intratumoral immunotherapy for patients with cancers across all stages of pathogenesis.

METHODS

An Intratumoral Immunotherapy Clinical Trials Expert Panel composed of international key stakeholders from academia and industry was assembled. A multiple choice/free response survey was distributed to the panel, and the results of this survey were discussed during a half-day consensus meeting. Key discussion points are summarized in the following manuscript.

RESULTS

The panel determined unique clinical trial designs tailored to different stages of cancer development-from premalignant to unresectable/metastatic-that can maximize the chance of capturing the effect of intratumoral immunotherapies. Design elements discussed included study type, patient stratification and exclusion criteria, indications of randomization, study arm determination, endpoints, biological sample collection, and response assessment with biomarkers and imaging. Populations to prioritize for the study of intratumoral immunotherapy, including stage, type of cancer and line of treatment, were also discussed along with common barriers to the development of these local treatments.

CONCLUSIONS

The SITC Intratumoral Immunotherapy Clinical Trials Expert Panel has identified key considerations for the design and implementation of studies that have the greatest potential to capture the effect of intratumorally delivered immunotherapies. With more effective and standardized trial designs, the potential of intratumoral immunotherapy can be realized and lead to regulatory approvals that will extend the benefit of these local treatments to the patients who need them the most.

721 Intratumoral immunotherapy with aluminum hydroxide-tethered IL-12 induces potent local and systemic immunity with minimal toxicity

Background

Interleukin-12 (IL-12) is a potent pro-inflammatory cytokine that promotes Th1 skewing, IFNγ expression, T- and NK-cell activation, and antigen presentation. In animal models, IL-12 can elicit robust anti-tumor responses through activation of both innate and adaptive immunity. However, clinical translation of IL-12 has been hindered by significant immune-related toxicity when delivered systemically, necessitating low doses that are often insufficient for efficacy. Intratumoral (IT) administration can expand the therapeutic window of IL-12 by increasing the local tumor concentration relative to systemic exposure but is in turn limited by rapid vascular and lymphatic clearance of injected drug from the tumor and corresponding systemic accumulation. Here we describe an approach to locally retain intratumorally administered IL-12 by complexing it to the common vaccine adjuvant aluminum hydroxide (alum) through a novel phosphopeptide linkage.

Methods

Single-chain murine IL-12 (mIL12) was genetically fused at its c-terminus to a short alum-binding peptide (ABP) that is specifically phosphorylated on multiple serines when co-expressed with the kinase Fam20C. Phosphorylated mIL12-ABP proteins were complexed with a 10x mass excess of aluminum hydroxide through a naturally occurring ligand exchange reaction between the phosphoserines in the ABP and surface hydroxyl groups on alum. mIL12-ABP/alum complexes were characterized for in vitro potency and in vivo efficacy in multiple syngeneic tumor models including MC38, CT26, A20, 4T1, and B16F10 following IT administration. Immune analyses and re-challenge experiments are in progress.

Results mIL12-ABP is phosphorylated on multiple sites when co-expressed with Fam20C and is stably retained on aluminum hydroxide in vitro under elution conditions containing phosphate and serum. Alum-bound mIL12-ABP remains active in cellular assays with a 3–4 fold increase in EC50 compared to free protein. Following intratumoral administration, the mIL12-ABP/alum complexes have significantly extended tumor retention compared to unmodified mIL12, leading to potent local immune activation for >1 week. One or two doses of IT administered mIL12-ABP/alum is sufficient to induce robust monotherapy efficacy in diverse syngeneic tumor models including cold tumors resistant to checkpoint blockade and other immunotherapies. Locally administered mIL12-ABP/alum is further able to prime a systemic immune response leading to efficacy against non-injected tumors and spontaneous metastases. Doses required for optimal efficacy are well tolerated in mice with no significant weight loss or other evidence of systemic toxicity.

Conclusions

Ankyra's platform is a differentiated approach to expand the therapeutic window of IL-12 and other cytokine drugs by enhancing tumor retention following IT administration.

Long-term progression-free survival of patients with metastatic melanoma or renal cell carcinoma following high-dose interleukin-2

High-dose interleukin-2 (HD IL-2) was approved in the 1990s after demonstrating durable complete responses (CRs) in some patients with metastatic melanoma (mM) and metastatic renal cell carcinoma (mRCC). Patients who achieve this level of disease control have also demonstrated improved survival compared with patients who progress, but limited data are available describing the long-term course. The aim of this study was to better characterize long-term survival following successful HD IL-2 treatment in patients with no subsequent systemic therapy. Eleven HD IL-2 treatment centers identified patients with survival ≥5 years after HD IL-2, with no subsequent systemic therapy. Survival was evaluated from the date of IL-2 treatment to June 2017. Treatment courses consisted of 2 1-week cycles of HD IL-2. Patients were treated with HD IL-2 alone, or HD IL-2 followed by local therapy to achieve maximal response. 100 patients are reported: 54 patients with mM and 46 patients with mRCC. Progression-free survival (PFS) after HD IL-2 ranges from 5+ years to 30+ years, with a median follow-up of 10+ years. 27 mRCC and 32 mM are alive ≥10 years after IL-2. Thus, a small subset of patients with mM and mRCC achieve long-term PFS (≥5 years) after treatment with HD IL-2 as their only systemic therapy. The ability of HD IL-2 therapy to induce prolonged PFS should be a major consideration in studies of new immunotherapy combinations for mM and mRCC.

422 An open-label, multicenter, phase 1/2 clinical trial of RP1, an enhanced potency oncolytic HSV, combined with nivolumab: updated results from the skin cancer cohorts

Background

RP1 is an enhanced potency oncolytic HSV encoding a fusogenic protein (GALV-GP R-) and GM-CSF which has previously demonstrated tolerable safety and tumor regression alone and with nivolumab in patients with a number of tumor types. Updated data from the phase 1 expansion with nivolumab, melanoma phase 2 (enrollment complete) and non-melanoma skin cancer (NMSC; enrollment ongoing) cohorts will be presented (NCT03767348). Enrollment of a further 125 patient anti-PD1 refractory cutaneous melanoma cohort; and activation of a cohort of anti-PD1 refractory NSCLC is underway.

Methods

Stage IIIb-IV melanoma patients for whom anti-PD-1 was indicated or who were refractory to prior anti-PD-1 alone or in combination with anti-CTLA-4, were enrolled. NMSC patients were anti-PD1 naïve. Patients received ≤8 doses of RP1 (≤10 mL/visit Q2W; first dose 106 PFU/mL then 107 PFU/mL) with nivolumab (240 mg IV Q2W for 4 months then 480 mg IV Q4W up to 2 years) from the second RP1 dose.

Results

As of 24th June 2020, 36 melanoma and 16 NMSC patients had been enrolled with follow up of <1–17 months. Of the melanoma patients, 16 previously anti-PD1 treated cutaneous (8 also prior anti-CTLA-4), 8 anti-PD1 naïve cutaneous, 6 mucosal, and 6 uveal. Of the NMSC patients, 10 had squamous cell (CSCC), 3 had a basal cell, 1 had Merkel cell carcinomas, and 2 had angiosarcoma. Treatment emergent adverse events (TEAEs) remain consistent with phase 1, with RP1 side effects generally of Grade 1/2 constitutional-type symptoms, with no exacerbation of the side effects expected for nivolumab. At the data cut-off, 5 previously anti-PD1 treated (4 also anti-CTLA-4) cutaneous melanoma patients, 4 anti-PD1 naïve cutaneous melanoma patients, two mucosal melanoma patients (one anti-PD1 refractory) and one uveal melanoma patient (ipi/nivo refractory) have achieved response (WHO criteria for uveal). For NMSC, for the 13 patients with >8 weeks follow up, one of two angiosarcoma patients and seven of eight CSCC patients (5 CR) have achieved response (CSCC ORR 87.5%; CR rate 62.5%, including of uninjected visceral disease). Tumor biopsies in patients continue to routinely show immune activation, including robust recruitment of CD8+ T cells, reversal of T cell exclusion, and increased PD-L1 expression. Treatment remains ongoing, and current data will be presented.

Conclusions

RP1 and nivolumab have continued to be well tolerated, with continued promising anti-tumor activity in patients with skin cancers, including those with anti-PD1 refractory and other difficult to treat melanomas, and in patients with CSCC.

Advanced bioinformatics rapidly identifies existing therapeutics for patients with coronavirus disease-2019 (COVID-19)

BACKGROUND

The recent global pandemic has placed a high priority on identifying drugs to prevent or lessen clinical infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), caused by Coronavirus disease-2019 (COVID-19).

METHODS

We applied two computational approaches to identify potential therapeutics. First, we sought to identify existing FDA approved drugs that could block coronaviruses from entering cells by binding to ACE2 or TMPRSS2 using a high-throughput AI-based binding affinity prediction platform. Second, we sought to identify FDA approved drugs that could attenuate the gene expression patterns induced by coronaviruses, using our Disease Cancelling Technology (DCT) platform.

RESULTS

Top results for ACE2 binding iincluded several ACE inhibitors, a beta-lactam antibiotic, two antiviral agents (Fosamprenavir and Emricasan) and glutathione. The platform also assessed specificity for ACE2 over ACE1, important for avoiding counterregulatory effects. Further studies are needed to weigh the benefit of blocking virus entry against potential counterregulatory effects and possible protective effects of ACE2. However, the data herein suggest readily available drugs that warrant experimental evaluation to assess potential benefit. DCT was run on an animal model of SARS-CoV, and ranked compounds by their ability to induce gene expression signals that counteract disease-associated signals. Top hits included Vitamin E, ruxolitinib, and glutamine. Glutathione and its precursor glutamine were highly ranked by two independent methods, suggesting both warrant further investigation for potential benefit against SARS-CoV-2.

CONCLUSIONS

While these findings are not yet ready for clinical translation, this report highlights the potential use of two bioinformatics technologies to rapidly discover existing therapeutic agents that warrant further investigation for established and emerging disease processes.

Advanced bioinformatics rapidly identifies existing therapeutics for patients with coronavirus disease-2019 (COVID-19)

BACKGROUND

The recent global pandemic has placed a high priority on identifying drugs to prevent or lessen clinical infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), caused by Coronavirus disease-2019 (COVID-19).

METHODS

We applied two computational approaches to identify potential therapeutics. First, we sought to identify existing FDA approved drugs that could block coronaviruses from entering cells by binding to ACE2 or TMPRSS2 using a high-throughput AI-based binding affinity prediction platform. Second, we sought to identify FDA approved drugs that could attenuate the gene expression patterns induced by coronaviruses, using our Disease Cancelling Technology (DCT) platform.

RESULTS

Top results for ACE2 binding iincluded several ACE inhibitors, a beta-lactam antibiotic, two antiviral agents (Fosamprenavir and Emricasan) and glutathione. The platform also assessed specificity for ACE2 over ACE1, important for avoiding counterregulatory effects. Further studies are needed to weigh the benefit of blocking virus entry against potential counterregulatory effects and possible protective effects of ACE2. However, the data herein suggest readily available drugs that warrant experimental evaluation to assess potential benefit. DCT was run on an animal model of SARS-CoV, and ranked compounds by their ability to induce gene expression signals that counteract disease-associated signals. Top hits included Vitamin E, ruxolitinib, and glutamine. Glutathione and its precursor glutamine were highly ranked by two independent methods, suggesting both warrant further investigation for potential benefit against SARS-CoV-2.

CONCLUSIONS

While these findings are not yet ready for clinical translation, this report highlights the potential use of two bioinformatics technologies to rapidly discover existing therapeutic agents that warrant further investigation for established and emerging disease processes.

An open label, multicenter, phase I/II study of RP1 as a single agent and in combination with PD1 blockade in patients with solid tumors

TPS2671

Background: RP1 is an attenuated oncolytic HSV-1 that expresses a fusogenic glycoprotein from gibbon ape leukemia virus (GALV-GP R-) and GM-CSF. RP1 induces potent GALV-GP R- enhanced immunogenic cell death and host anti-tumor immunity in murine tumor models and increases PD-L1 expression. This clinical trial (NCT03767348) was designed to test the hypotheses that RP1 is safe when given alone and together with nivolumab (phase 1) and has efficacy together with nivolumab in four tumor types (phase 2). Methods: The primary goals of this clinical trial in a total of ~150 patients are to define the safety profile of RP1 alone and together with nivolumab, determine the recommended phase 2 dose (phase 1), and then in four phase 2 cohorts, to determine objective response rate in patients with melanoma, non-melanoma skin cancer, urothelial carcinoma and MSI-H solid tumors. Secondary objectives include duration of response, CR rate, PFS, viral shedding, and immune biomarker analysis. Patients with advanced cancer who failed prior therapy were eligible for the phase I component. In Phase 2 patients with histologic diagnoses of the four tumor types (N=30 for each) and who meet safety criteria for nivolumab treatment are eligible. Prior treatment with checkpoint blockade is not allowed except for the melanoma cohort. In the phase 1 portion patients are treated by intra-patient dose escalation of virus (range, 104 - 108 PFU) by intratumoral injection every two weeks for 5 total doses followed by 12 patients dosed 8 times at the RP2D in combination with nivolumab. Phase 1 patients were divided into two groups based on presence of clinically accessible lesions amenable to direct injection or those with visceral/deep lesions requiring image guidance for injection. In the phase 2 portion patients will receive the RP2D for eight injections and nivolumab will be given starting with the second RP1 injection. For the phase 1 portion, a modified 3+3 dose escalation design is used to assess safety and in the phase 2 portion, statistical analysis will be performed using a two-stage three-outcome optimum design with objective responses determined by RECIST criteria. As of February 11, 2019, 27 patients have been enrolled. Clinical trial information: NCT03767348.

Overall survival by clinical risk category for high dose interleukin-2 (HD IL-2) treated patients with metastatic renal cell cancer (mRCC): data from the PROCLAIMSM registry

BACKGROUND

Prognostic scoring systems are used to estimate the risk of mortality from metastatic renal cell carcinoma (mRCC). Outcomes from different therapies may vary within each risk group. These survival algorithms have been applied to assess outcomes in patients receiving T-cell checkpoint inhibitory immunotherapy and tyrosine kinase inhibitor therapy, but have not been applied extensively to patients receiving high dose interleukin-2 (HD IL-2) immunotherapy.

METHODS

Survival of 810 mRCC patients treated from 2006 to 2017 with high dose IL-2 (aldesleukin) and enrolled in the PROCLAIMSM registry data base was assessed utilizing the International Metastatic RCC Database Consortium (IMDC) risk criteria. Median follow-up is 23.4 months (mo.) (range 0.2-124 mo.). Subgroup evaluations were performed by separating patients by prior or no prior therapy, IL-2 alone, or therapy subsequent to IL-2. Some patients were in two groups. We will focus on the 356 patients who received IL-2 alone, and evaluate outcome by risk factor categories.

RESULTS

Among the 810 patients, 721 were treatment-naïve (89%) and 59% were intermediate risk. Overall, of the 249 patients with favorable risk, the median overall survival (OS) is 63.3 mo. and the 2-year OS is 77.6%. Of 480 patients with intermediate risk, median OS is 42.4 mo., 2-year OS 68.2%, and of 81 patients with poor risk, median OS 14 mo., 2-year OS 40.4%. Among those who received IL-2 alone (356 patients), median OS is 64.5, 57.6, and 14 months for favorable, intermediate and poor risk categories respectively. Two year survival among those treated only with HD IL-2 is 73.4, 63.7 and 39.8%, for favorable, intermediate and poor risk categories respectively.

CONCLUSIONS

Among mRCC patients treated with HD IL-2, all risk groups have median and 2-year survival consistent with recent reports of checkpoint or targeted therapies for mRCC. Favorable and intermediate risk (by IMDC) patients treated with HD IL-2 have longer OS compared with poor risk patients, with most durable OS observed in favorable risk patients. Favorable risk patients treated with HD IL-2 alone have a 2-year OS of 74%. These data continue to support a recommendation for HD IL-2 for patients with mRCC who meet eligibility criteria.

TRIAL REGISTRATION

PROCLAIM, NCT01415167 was registered with ClinicalTrials.gov on August 11, 2011, and initiated for retrospective data collection until 2006, and prospective data collection ongoing since 2011.

Dose intensification of TRAIL-inducing ONC201 inhibits metastasis and promotes intratumoral NK cell recruitment

ONC201 is a first-in-class, orally active antitumor agent that upregulates cytotoxic TRAIL pathway signaling in cancer cells. ONC201 has demonstrated safety and preliminary efficacy in a first-in-human trial in which patients were dosed every 3 weeks. We hypothesized that dose intensification of ONC201 may impact antitumor efficacy. We discovered that ONC201 exerts dose- and schedule-dependent effects on tumor progression and cell death signaling in vivo. With dose intensification, we note a potent anti-metastasis effect and inhibition of cancer cell migration and invasion. Our preclinical results prompted a change in ONC201 dosing in all open clinical trials. We observed accumulation of activated NK+ and CD3+ cells within ONC201-treated tumors and that NK cell depletion inhibits ONC201 efficacy in vivo, including against TRAIL/ONC201-resistant Bax-/- tumors. Immunocompetent NCR1-GFP mice, in which NK cells express GFP, demonstrated GFP+ NK cell infiltration of syngeneic MC38 colorectal tumors. Activation of primary human NK cells and increased degranulation occurred in response to ONC201. Coculture experiments identified a role for TRAIL in human NK-mediated antitumor cytotoxicity. Preclinical results indicate the potential utility for ONC201 plus anti-PD-1 therapy. We observed an increase in activated TRAIL-secreting NK cells in the peripheral blood of patients after ONC201 treatment. The results offer what we believe to be a unique pathway of immune stimulation for cancer therapy.

High dose interleukin-2 and response in 944 patients with metastatic renal cell cancer (RCC): Data from the PROCLAIM registry

624

Background: High dose interleukin-2 (HD IL2) has traditionally been dosed every 8 hours for a maximum of 14 doses each cycle. We evaluated whether alternate dosing schedules and dose intensity affected achievement of complete response (CR) or partial response (PR) in the PROCLAIM registry. Methods: Patients with metastatic RCC were enrolled retrospectively and prospectively into the PROCLAIM registry to collect outcome data. Statistical methods for comparisons were done using Fisher’s and Chi Square tests. Results: From 2006-2017 the registry included 944 RCC patients; 257 (27%) women, 676 (72%) men. 844 (89%) were white. Histologic distribution: 624 (66%) clear cell, 93 (10%) medullary, 79 (8%) collecting duct, 78 (8%) chromophobe and 70 (7%) papillary. 207 (22%) had prior therapy with VEGF/mTOR. Best response was 51 (5.4%) CR and 169 (17.9%) PR; 263 (28%) progressive disease. 13 (1.4%) patients received q12 hour dosing while 830 (88%) received q8 hour dosing. 608 (64%) received 600 KIU/kg and 67 (7%) received 720 KIU/kg. Median # of doses in cycle 1 was 10 for CR and PR patients at 600 KIU/kg and 9 for those with stable or progressive disease. In the 720 KIU/kg group median #doses was 11 for CR, 8 for PR, and 7 for stable or progressive disease. In cycle 2 median doses received was 7.16 for patients with CR, 7.02 for PR and 6.76 for stable disease. Median dose intensity is similar at these two dose levels. Associations with achievement of CR/PR are summarized in the Table. Conclusions: There is no difference in response rate based on dosing schedule but the small number of subjects dosed q12 hours limits interpretation. Good performance patients possess the best opportunity for benefit from HD IL2. There is a trend for response with higher median # doses. Further studies of alternate dosing schedules are warranted. Clinical trial information: NCT01415167. [Table: see text]

A phase II study of talimogene laherparepvec followed by talimogene laherparepvec + nivolumab in refractory T cell and NK cell lymphomas, cutaneous squamous cell carcinoma, Merkel cell carcinoma, and other rare skin tumors (NCI #10057)

TPS219

Background: Talimogene laherparepvec, a modified herpes virus agent, induces a response in 65% of injected melanoma tumors. The combination of talimogene laherparepvec with ipilimumab or pembrolizumab appears promising in clinical trials of advanced melanoma. Talimogene laherparepvec-based therapy may be effective in other cancers of the skin and lymph nodes that are anatomically accessible for intratumoral injection. Methods: This phase II study will evaluate intratumoral talimogene laherparepvec monotherapy in 4 parallel disease cohorts: 1) Refractory T cell and NK cell lymphomas including cutaneous T cell lymphoma, 2) Merkel cell carcinoma 3) Cutaneous squamous cell carcinoma and 4) Other advanced/refractory non-melanoma skin cancers. Lymphoma patients must be refractory to or intolerant of all standard life-prolonging therapies. Skin cancer patients must be advanced/unresectable or refractory to one or more treatments including surgery, radiation therapy, or medical therapy. Prior PD-1-directed therapy is allowed. If an objective response is not achieved by Week 12, the PD-1 blocking antibody nivolumab will be added. The primary endpoint is the response rate with talimogene laherparepvec and secondary endpoints include response rate with the combination and overall survival. Using a two-stage design, if 1 or more response is observed in the first 9 patients in each parallel cohort, 8 additional patients will be accrued for a total sample size of 36 to 68 patients across the 4 disease cohorts. Tumor biopsies of injected lesions are mandatory at baseline and Week 6, and optional at Week 16 and the time of progression. Optional biopsies of non-injected lesions (when applicable) at Week 6 and 16 will be analyzed to identify biomarkers of systemic immunity. Tumor tissue and/or blood will be assayed for PD-L1 expression, RNA profiling, immune cell profiling, HVEM, NECTIN 1/2, IDO, tryptophan and L-kynurenine, mutational load, TIL TCR clonality, and prior exposure to herpes simplex type 1 virus and Merkel cell polyomavirus. Clinical trial information: NCT02978625.

Abstract 124: Imipridone ONC201 promotes intra-tumoral accumulation of CD3+/NK+ cells that contribute to its anti-tumor efficacy

ONC201, a first-in-class oral anti-tumor agent, upregulates the pro-apoptotic immune cytokine TRAIL and activates the integrated stress response leading to upregulation of death receptor 5 in bulk tumor and cancer stem cells. We previously demonstrated that ONC201 exerts a dose- and schedule-dependent effect on tumor progression in vivo while suppressing Akt/ERK signaling in tumors in a dose/frequency-dependent manner (Wagner et al., AACR, 2016). We also provided evidence that ONC201 exhibits a potent anti-metastatic effect (Wagner et al., AACR, 2016). We observe accumulation and activation of TRAIL-secreting NK+ cells within ONC201-treated tumors in C57/BL6, Balb/c, and athymic nude tumor-bearing mice. Importantly, ONC201 exerts in vivo anti-tumor efficacy on tumor cell lines that are ONC201-resistant in vitro, including acquired stable resistance. Using the NK-depleting antibody GM1, we demonstrate that the activation and TRAIL secretion of NK cells by ONC201 significantly contributes to in vivo anti-tumor efficacy, including TRAIL/ONC201-resistant tumors. We are currently investigating how ONC201 recruits NK cells to the tumor by examining NK-recruiting chemokine factors within the tumor site. We have also demonstrated upregulation of CD3+ T cells by ONC201 in syngeneic mice. Finally, we observed an increase in activated TRAIL-secreting NK cells in the peripheral blood of patients upon ONC201 administration in the clinic. Our results demonstrate novel and potentially significant increases in cytotoxic NK cell recruitment to tumors. The results offer a unique pathway of immune stimulation for cancer therapy that may be combined with immune checkpoint or targeted cancer therapy strategies. We are currently investigating the role of NK cells and CD3+ cells in ONC201’s ability to inhibit metastasis by using a metastatic model that involves surgically removing the primary tumor and allowing metastases to grow in vivo before treatment. These findings indicate that ONC201 possess immunomodulatory activity and provide a rationale for combining ONC201 with PD-1/PDL-1 inhibitors, a combination we are currently testing in syngeneic immunocompetent mouse models.

Citation Format: Jessica Wagner, C. Leah Kline, Lanlan Zhou, Andrew Zloza, Charles Chesson, Jenna Newman, Howard Kaufman, Joseph Bertino, Mark Stein, Wafik El-Deiry. Imipridone ONC201 promotes intra-tumoral accumulation of CD3+/NK+ cells that contribute to its anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 124. doi:10.1158/1538-7445.AM2017-124

Clinical activity of the selective DRD2 antagonist ONC201, an imipridone, in metastatic endometrial cancer (mEC)

5592

Background: mEC is a generally incurable, with limited therapeutic options. ONC201 is the founding member of the new class of compounds called imipridones that are orally active small molecules. ONC201 a specific antagonist of the G protein-coupled receptor DRD2 exerts antitumor activity via a series of established signaling pathways (dual inhibition ERK/AKT, integrated stress response). DRD2 expression is elevated in malignant versus normal endometrial tissue. Furthermore ONC201 has shown anti-cancer activity in preclinical models of EC. Methods: In a Phase I trial that included an expansion cohort, a total of 28 evaluable patients (pts) were treated with ONC201 at doses from 125mg every 3 weeks to 625 weekly. Five of these patients had advanced mEC. Results: The median age for the mEC patients was 60 years (56-72), the median number of prior treatments was 5 (3-6), 3 patients had prior radiation and all patients had prior surgery. One patient received 375mg ONC201 while the other 4 patients received 625mg ONC201, orally every 3 weeks. The median number of doses was 3 (2-14). Two of 5 patients exhibited regressions in individual metastatic lesions, however they did not qualify as overall objective responses by RECIST criteria. One of these two patients experienced stable disease for 42 weeks. There were no reported SAEs and no Grade > 1 AEs attributed to study drug. Conclusions: ONC201 is clinically active and well tolerated with oral administration in refractory mEC patients. Clinical trial information: NCT02250781. [Table: see text]

Long-term (LT) disease-free survival (DFS) of melanoma (MM) and renal cell cancer (RCC) patients following high-dose interleukin-2 (HD IL2)

e21005

Background: HD IL2 treatment (Tx) produces durable complete responses (CRs) and surgical CRs. Patients (pts) achieving partial response (PR) and stable disease (SD) demonstrate improved survival compared with pts who progress. Methods: 7 HD IL2 Tx centers identified pts with survival > 5 years (yrs) after HD IL2. DFS was from end of IL2 to January 2017. Tx courses generally consisted of 2 1-week cycles of HD IL2, 600,000-720,000 U/kg IV every 8 hours. We collected data on pts Tx with HD IL2 alone, or HD IL2 plus local Tx (surgery or radiation (SRS) leading to CR) with survival > 5 yrs after HD IL2 Tx. Results: 72 pts are reported: 29 RCC (male 22, female 7) and 43 mm (male 26, female 17). Median age at Tx of RCC is 54 yrs (range, 47-67 yrs) and of mm is 50 yrs (range, 24-72 yrs). Sites of metastatic disease for 26 mm pts were lymph nodes (LN) -18, lungs-12, bone-6, liver-9, brain-3, other organs-10 and for 22 RCC pts were lung-17, LN-5, adrenal-4, bone-3, other organs-8. Number of IL2 courses received: 1-10 pts, 1.5-4 pts, 2-28 pts, 2.5-5 pts, 3-24 pts, 4-one pt. Among the 29 RCC pts, there are 24 CRs, 3 surgical CRs and 2 PRs with no further Tx. Among 43 mm pts, there are 34 CRs, 2 near CRs, and 7 Surgical/SRS CRs. DFS in these pts after HD IL2 Tx ranges from 5+ yrs to 30+ yrs, median 10.5+ yrs. 10 RCC and 16 mm are alive > 5 - < 10 yrs after IL2, and 19 RCC and 27 mm are alive > 10 yrs after IL2. LT toxicity among these 72 pts includes hypothyroidism-5 pts, arthralgias/arthritis-5 pts, vitiligo-3 pts, and 1 pt each: neuropathy, PVCs, and normal pressure hydrocephalus. Additional pts may be added as records become available. Conclusions: We document LT DFS ( > 5 yrs) after CR or PR from HD IL2 alone. Surgical or SRS conversion of PR to CR can produce durable CRs. LT DFS was observed in pts with visceral and bone metastases, not only those with LN or lung sites. Neither age, sex, nor number of courses of IL2 predicted LT DFS. Chronic toxicity due to IL2 is uncommon in LT survivors.

Non-progression during avelumab treatment is associated with clinically relevant improvements in health-related quality of life in patients with Merkel cell carcinoma

e21070

Background: There is little data on quality of life (QoL) for patients (pts) with Merkel cell carcinoma (MCC). To better understand how new treatments might impact QoL in MCC, pts with stage IV chemotherapy-treated MCC from a single-arm, open-label, multicenter, international phase 2 trial (NCT02155647) of a novel immunotherapy were followed for QoL and clinical outcomes. Methods: Because there is no MCC-specific QoL instrument, the FACT-Melanoma (FACT-M), a validated QoL questionnaire including multiple subscales and summary scores (Trial Outcome Index [TOI], FACT-G total and FACT-M total) was used. Pts completed the FACT-M at baseline (BL), week 7, every 6 weeks until disease progression (PD) and at end of treatment (EOT). Linear mixed models (LMM) were fitted for change from BL for each scale including the time-varying covariate PD vs non-PD. Established minimal important differences (MID) were used to interpret meaningfulness of changes. Sensitivity analyses explored the effects of missing data. Results: 70 pts were analyzed. Overall, no meaningful changes from BL were observed for each scale during treatment. Moderate correlations between reduction in tumor size and improvements in FACT-M were observed at week 7 for Functional Well-being (-0.47), TOI (-0.36), FACT-M total (-0.36), and FACT-G total (-0.34), suggesting improvements in QoL with tumor shrinkage. LMM showed differences between PD vs non-PD groups in the range of MIDs for Functional Well-being (2.23, p = 0.018), Melanoma (3.19, p = 0.012), Surgery (1.95, p = 0.109), TOI (6.36, p = 0.012) and FACT-G total (3.89, p = 0.105). These models showed improvement for the non-PD group in Emotional Well-being (1.55, p = 0.004) and worsening for the PD group in Physical Well-being (-1.63, p = 0.041), Surgery (-2.09, p = 0.044) and TOI (-4.56, p = 0.036). As expected, all scales worsened in the range of MIDs at EOT, mostly due to PD. Sensitivity analyses were consistent, with modest increases in estimated differences. Conclusions: In pts with metastatic MCC, non-progression during avelumab treatment contributed to statistically and clinically meaningful improvements in health-related QoL. Clinical trial information: NCT02155647.

First-line (1L) avelumab treatment in patients (pts) with metastatic Merkel cell carcinoma (mMCC): Preliminary data from an ongoing study

9530

Background: MCC is a rare, aggressive skin cancer. Avelumab is a fully human anti–PD-L1 antibody. In a phase 2 study in pts with distant mMCC who progressed after prior chemotherapy (JAVELIN Merkel 200; NCT02155647), avelumab showed a manageable safety profile and durable responses, including an objective response rate (ORR) of 31.8%, estimated 6-month durable response rate of 29%, and 6-month overall survival rate of 69%. Here, we report preliminary results from a separate cohort of pts with chemotherapy-naïve mMCC enrolled in the same study. Methods: Eligible pts with mMCC and no prior systemic treatment for metastatic disease received avelumab 10 mg/kg Q2W until confirmed progression, unacceptable toxicity, or withdrawal. Tumors were assessed every 6 weeks (RECIST v1.1). Adverse events (AEs) were assessed by NCI CTCAE v4.0. Results: As of Dec 30, 2016, 29/112 planned pts had been enrolled. Median age was 75.0 years (range 47–87). Median treatment duration was 8.1 weeks (range 2.0–37.9). Of 16 pts with ≥3 months of follow-up, unconfirmed ORR was 68.8% (95% CI 41.3–89.0) with CR in 18.8%; confirmed ORR was 56.3% (95% CI 29.9–80.2; 1 unconfirmed PR with discontinuation). Of 25 pts with ≥6 weeks of follow-up, unconfirmed ORR was 64.0% (95% CI 42.5–82.0). All responses were ongoing at last follow-up, including in 5/5 pts with ≥6 months of follow-up (potential to confirm responses). 20/29 pts (69.0%) had a treatment-related AE (TRAE), including grade 3–4 TRAE in 5 pts (17.2%). TRAEs led to discontinuation in 5 pts (17.2%): 2 pts with infusion-related reaction, and 1 pt each with elevated AST and ALT, cholangitis, and paraneoplastic syndrome. There were no treatment-related deaths. 21/29 pts (72.4%) remain on treatment. Conclusions: In initial results from a cohort of chemotherapy-naïve pts with mMCC, avelumab was associated with early responses and a manageable safety profile, consistent with findings for second-line or later avelumab treatment in a previous cohort. These results suggest that responses mature to become durable and the use of 1L avelumab may increase the probability of response vs later-line treatment. Enrollment and follow-up in this 1L cohort are ongoing. Clinical trial information: NCT02155647.

Exploratory biomarker analysis in avelumab-treated patients with metastatic Merkel cell carcinoma progressed after chemotherapy

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Background: Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer. Tumor oncogenesis is linked to Merkel cell polyomavirus (MCPyV) integration and UV exposure. PD-L1 is often expressed in MCC tumors, suggesting that patients with MCC could benefit from anti-PD-L1 therapy. Avelumab is a fully human anti-PD-L1 IgG1 monoclonal antibody that has demonstrated clinical efficacy in patients (pts) with metastatic MCC (mMCC) in a Phase 2 trial with an objective response rate (ORR) of 31.8% in the primary analysis. Assessment of candidate predictive biomarkers may help to identify patients with a greater probability of response to avelumab and to improve understanding of MCC biology. Methods: Patients in a Phase 2 trial (NCT02155647) with mMCC and tumor progression on prior chemotherapy received avelumab at 10 mg/kg Q2W. PD-L1 expression, MCPyV status and CD8+ T-cell infiltration in pretreatment tumor samples were evaluated by immunohistochemistry (IHC). MCPyV status was also evaluated by real-time PCR. Results: Tumor PD-L1 expression was evaluable in 74 of 88 (84.1%) pts with mMCC treated with avelumab, of which 58 (65.9%) and 19 (21.6%) pts were positive at 1% and 5% cut-offs. ORR was 34.5% and 18.8% for PD-L1 positive and negative pts at 1% cutoff, and 52.6% and 23.6% for PD-L1 positive and negative pts at 5% cutoff. MCPyV status was positive in 60% (46/77) pts evaluable by IHC and 63% (45/71) pts evaluable by PCR; of 66 pts tested by both IHC and PCR, concordance was 90.9%. MCPyV+ and MCPyV– pts had similar frequencies of PD-L1+ tumors (80% and 73%) with an ORR of 26.1% and 35.5% respectively. Baseline CD8+ T-cell infiltration was assessed at tumor invasive margin and tumor center in 53 pts, ORR was 44.4% vs 19.2% and 32.1% vs 28% for pts with high or low CD8+ T-cell density at respective locations. Conclusions: In an international cohort of pts with mMCC, avelumab had clinical activity among biomarker subgroups analyzed, including PD-L1 expression, MCPyV status and density of CD8+ tumor-infiltrating T-cells. The current biomarkers were not predictive of response but further research into understanding how avelumab mediates anti-tumor activity in MCC may identify novel biomarkers. Clinical trial information: NCT02155647.

Association of improved survival (OS) and tumor control (TC) with interleukin-2 (IL2) with development of immune-related events (IREs): Data from the PROCLAIMSM registry

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Background: IREs are associated with immunotherapy (IT) for cancer and while reports suggest improvement in TC and OS with induced IREs, the long-term impact is unclear. IL2 has been the major IT for patients (pts) with renal cell carcinoma (RCC) and melanoma (MM) since 1992. We evaluated IREs reports in the PROCLAIMSM data base (2008-2016) of IL2-treated pts. Methods: Reports on 614 (MM) and 843 (RCC) pts were queried for IREs. IREs were categorized as occurring before, during, or after IL-2 and related to any checkpoint inhibitor (CPI). TC (CR+PR+SD) was compared between no IRE and IRE, using Fisher’s exact test. OS curves were estimated by Kaplan-Meier method, and comparison of no IRE/before IL2 with during/after IL2, was analyzed by log-rank test. Results: With a median (med) follow-up of 3.5+ years (range 1-8+ year), 140 IREs were reported in 118 pts (9.6% of all PROCLAIMSM pts): 93 (15%) in MM; 47 (5.6%) in RCC. 25 IREs were prior to IL2; 13 IREs were during IL2; 102 were after IL2. Of the latter 102, 31 were after IL2 and after subsequent CPI; 71 were attributed to IL2 only; and in 13, IREs were due to either IL2 or CPI. TC was 73% for IRE group vs 56% for no IRE group (p = 0.0054). OS was significantly greater for IRE group during/after IL2 compared to no IRE/before IL2 in MM, med 46 months (mo) vs 18 mo (p = 0.0001) and in RCC, med 61 mo vs 43 mo (p = 0.0196), independent of CPI IREs. Med # of IL2 doses was 19 in no IRE group, 39 in IRE during IL2 group, and 25 in IRE after IL2 group. IL2-related IREs were primarily vitiligo and thyroid dysfunction (70% of IL2 IREs), with limited further impact, while CPI-related IREs were often serious, requiring intervention (hypophysitis, colitis, hepatitis, uveitis) (52% of CPI IREs) and possibly chronic management. Conclusions: IREs following IL2 are associated with improved TC and OS. IREs resulting from IL2 and from CPIs are qualitatively different and likely reflect different mechanisms of action of immune activation and response.

Patient experiences with avelumab vs chemotherapy for treating merkel cell carcinoma: Results from protocol-specified qualitative research

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Background: Avelumab is a fully human anti–PD-L1 monoclonal antibody that has shown durable responses and a manageable safety profile in patients (pts) with various tumors, including metastatic Merkel cell carcinoma (mMCC). We report findings from qualitative interviews with mMCC pts about their experiences with avelumab or chemotherapy. Methods: Pts with mMCC who progressed after chemotherapy were enrolled in a registrational, single-arm, multicenter, international phase 2 trial (NCT02155647). Protocol-specified semi-structured phone interviews were conducted at baseline (to document experiences with chemotherapy) and during avelumab treatment at Weeks 13 and 25. Interview transcripts were analyzed qualitatively using a thematic approach. Results: Interviews were conducted with 19 pts at baseline and 10 pts at Weeks 13 and 25. At baseline, most pts (n = 12) reported that chemotherapy was initially successful prior to relapse. At Week 13, pts generally were “optimistic,” but “cautious,” and had “high hopes” regarding avelumab treatment. Pts most frequently reported having no or fewer side effects (n = 6) with avelumab vs prior chemotherapy. At Week 13, fatigue was the most frequently reported impact of avelumab (n = 8); at Week 25, 3 pts still reported fatigue, but 5 “felt less tired” than at Week 13. Most pts (n = 12) had experienced fatigue with chemotherapy; having “less energy” was the most-reported effect (n = 4) when compared with avelumab. Most pts did not report any negative impact of avelumab on everyday lives (n = 7); 3 reported a need “to rest more often after activities.” In contrast, only 6/19 pts reported that chemotherapy had no negative impact or a” very small” negative impact on everyday lives. Eight pts reported feeling “slowed down” or “being limited” in physical capacities during chemotherapy. Eight pts thought that chemotherapy had substantial negative impact on their lives, describing it as “very disruptive,” “debilitating,” or “devastating.” Conclusions: Pts had a more positive experience with avelumab than chemotherapy; it had a minimal detrimental impact on their lives. Clinical trial information: NCT02155647.

Anticancer and immunostimulatory activity of the imipridone ONC201, a selective DRD2 antagonist, in advanced cancer patients

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Background: ONC201 is an orally active, small molecule selective antagonist of the G protein-coupled receptor DRD2 that has established a new class of compounds referred to as imipridones. A first-in-human trial of ONC201 defined its recommended phase II dose (RP2D) as 625mg using once every three week administration that was very well tolerated at doses that yielded antitumor effects. ONC201 also showed stimulatory effects on immune cells in preclinical studies, including increased intratumoral NK cell infiltration in xenografts. Based on the exceptional safety profile of ONC201, weekly dosing has been evaluated. Methods: This open-label, 3+3 dose-escalation study used a starting dose of 375mg and escalated to 625mg using a weekly administration schedule. The primary endpoint was to determine the RP2D of ONC201 and secondary endpoints included PD, PK, toxicity, and anti-tumor efficacy. Based on signs of clinical activity and preclinical tumor type sensitivity studies of ONC201, the patient population was enriched for advanced glioblastoma, prostate cancer, and endometrial cancer. Six additional patients were treated at the weekly RP2D. Results: The RP2D for the weekly regimen was defined as 625 mg. Twelve evaluable patients were treated at this dose level and no drug-related AEs > grade 1 occurred. Five patients had stable disease by RECIST criteria for 21-29 weeks. A metastatic prostate cancer who received 375mg ONC201 weekly had significantly diminished intensity in bone scans after 6 doses. PK was consistent with previous reports: Cmax consistently reaches therapeutic micromolar plasma concentrations, ~11 hour half-life, evidence of sustained and delayed activity, no systemic accumulation. In agreement with preclinical observations of ONC201-induced NK cell populations, a 2-10 fold increase in circulating activated NK cells was observed in 5 prostate cancer patients. Conclusions: ONC201 is well tolerated at an oral dose of 625mg weekly, exhibits sustained and late anti-cancer activity, and increases circulating NK cells. Observation in this study, and other clinical studies, warrant further evaluation of the immune oncology effects of ONC201. Clinical trial information: NCT02250781.

Evaluation of clinical endpoints as surrogates for overall survival in patients treated with immunotherapies

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Background: In immuno-oncology (IO), the correlation between clinical trial endpoints, specifically, objective response rate (ORR), disease control rate (DCR) or progression free survival (PFS), and overall survival (OS) is poorly understood. The effect of IO agents as opposed to chemotherapy, is not on tumor cells, but on immune cells and OS benefit has been observed in absence of PFS benefit. However, decisions on registration trials often rely on PFS from Phase II trials. Methods: We conducted a systematic literature review with PubMed and Embase (Jan. 2005–Nov. 2016), supplemented with oncology conference proceedings (2014–2016). Eligible studies were randomized controlled trials (RCT) that investigated ≥1 immune checkpoint blockers (CBs) targeting programmed death proteins (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and reported their relative effect on OS and on ≥1 of the clinical endpoints, DCR, ORR, and PFS. Log-transformed hazard ratios were fitted using weighted regression models to determine the power of relative effects on clinical endpoints to predict OS effects, with correlation coefficients estimated and presented with adjusted R2 (high values indicating better goodness-of-fit). Results: This analysis included 18 RCTs involving 7140, patients. Most studies (10/18) evaluated the efficacy of CBs vs conventional chemotherapy, whereas 8 studies compared the efficacy of ≥1 CB. Among trials that evaluated anti-CTLA-4, the adjusted R2 for the relative efficacy of CBs on DCR, ORR, PFS, and relative efficacy of CBs on OS were 0.160 ( P= 0.156), 0.016 ( P= 0.332), and 0.000 ( P= 0.623) respectively. Among trials that evaluated either anti-PD-1 or anti-PD-L1, the adjusted R2 were 0.038 ( P= 0.401), 0.066 ( P= 0.251), and 0.432 ( P= 0.032), for DCR, ORR and PFS respectively. Among trials that evaluated CBs in melanoma, the adjusted R2 were 0.030 ( P= 0.267), 0.028 ( P= 0.279), and 0.192 ( P= 0.154), for DCR, ORR, and PFS respectively. Conclusions: No clear correlations were observed between relative effects of conventional clinical endpoints and OS for CBs. New surrogate endpoints may be needed to better predict OS benefit for CBs and other forms of cancer immunotherapy.

Radiation Therapy and Talimogene Laherparepvec (TVEC) Synergize in the Treatment of Melanoma

Talimogene laherparepvec (TVEC), an oncolytic virus, is an FDA-approved therapy that increases the overall survival of locally advanced and metastatic melanoma patients. Radiation therapy (RT) in combination with immunotherapies improves response rates (compared to either modality alone). Therefore, we hypothesized that combination RT and TVEC results in a synergistic therapeutic effect on melanoma. We treated 8 human melanoma cell lines with radiation (0, 4, or 8 Gy) and/or T-VEC (0, 0.01, 0.1, or 1 MOI) and determined its therapeutic effects using the AlamarBlue cell viability assay. Treatment of UACC257 melanoma cells with combination RT (8 Gy) and TVEC (1 MOI) resulted in a significant decrease in tumor cell viability (a decrease of 44.9%) compared to no treatment, RT alone (33.2%, P=0.0004), or T-VEC alone (24.2%, P=0.0088), with similar findings in other cell lines. We then injected a B16 mouse melanoma cell line, permissive to T-VEC infection, into B6 mice to assess in vivo synergy. Mice were treated when tumors were ~7mm × 7mm. RT resulted in an early 20% decrease in tumor size within 4 days, followed by an increase thereafter. Intra-tumoral TVEC resulted in no clear benefit until 9 days post-treatment, when it showed a slight decrease in size sustained for ~10 days. Combination treatment, however, led to an early response that was sustained until 18 days after the initial treatment. When tumors were assessed 18 days after initial treatment, a 3-fold or more increase in tumor size was lowest in the combination T-VEC + RT group (17%) compared to the control (100%), RT (60%), or TVEC (50%) groups. These data propose that combination T-VEC + RT may be beneficial for cancer patients, and studies establishing the mechanism of synergy are ongoing.

Clinical Actionability of Comprehensive Genomic Profiling for Management of Rare or Refractory Cancers

BACKGROUND

The frequency with which targeted tumor sequencing results will lead to implemented change in care is unclear. Prospective assessment of the feasibility and limitations of using genomic sequencing is critically important.

METHODS

A prospective clinical study was conducted on 100 patients with diverse-histology, rare, or poor-prognosis cancers to evaluate the clinical actionability of a Clinical Laboratory Improvement Amendments (CLIA)-certified, comprehensive genomic profiling assay (FoundationOne), using formalin-fixed, paraffin-embedded tumors. The primary objectives were to assess utility, feasibility, and limitations of genomic sequencing for genomically guided therapy or other clinical purpose in the setting of a multidisciplinary molecular tumor board.

RESULTS

Of the tumors from the 92 patients with sufficient tissue, 88 (96%) had at least one genomic alteration (average 3.6, range 0-10). Commonly altered pathways included p53 (46%), RAS/RAF/MAPK (rat sarcoma; rapidly accelerated fibrosarcoma; mitogen-activated protein kinase) (45%), receptor tyrosine kinases/ligand (44%), PI3K/AKT/mTOR (phosphatidylinositol-4,5-bisphosphate 3-kinase; protein kinase B; mammalian target of rapamycin) (35%), transcription factors/regulators (31%), and cell cycle regulators (30%). Many low frequency but potentially actionable alterations were identified in diverse histologies. Use of comprehensive profiling led to implementable clinical action in 35% of tumors with genomic alterations, including genomically guided therapy, diagnostic modification, and trigger for germline genetic testing.

CONCLUSION

Use of targeted next-generation sequencing in the setting of an institutional molecular tumor board led to implementable clinical action in more than one third of patients with rare and poor-prognosis cancers. Major barriers to implementation of genomically guided therapy were clinical status of the patient and drug access. Early and serial sequencing in the clinical course and expanded access to genomically guided early-phase clinical trials and targeted agents may increase actionability.

IMPLICATIONS FOR PRACTICE

Identification of key factors that facilitate use of genomic tumor testing results and implementation of genomically guided therapy may lead to enhanced benefit for patients with rare or difficult to treat cancers. Clinical use of a targeted next-generation sequencing assay in the setting of an institutional molecular tumor board led to implementable clinical action in over one third of patients with rare and poor prognosis cancers. The major barriers to implementation of genomically guided therapy were clinical status of the patient and drug access both on trial and off label. Approaches to increase actionability include early and serial sequencing in the clinical course and expanded access to genomically guided early phase clinical trials and targeted agents.

Durability of responses in patients with metastatic renal cell carcinoma treated with high-dose interleukin-2 (HD IL-2)

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Background: HD IL-2 is FDA approved for advanced renal cell carcinoma (mRCC), however, the data supporting its use is 23 years old. In 2011, a HD IL-2 patient database was established called PROCLAIMSM, and comprises the largest active prospective collection of data from mRCC and metastatic melanoma (MM) patients receiving HD IL-2 treatment and provides longitudinal real-time insights into the clinical impact of sequencing drug treatments. These data report on the outcomes and interactions with prior targeted therapies in mRCC patients in the current era. Methods: Inclusion criteria require patients to receive at least one dose of HD IL-2. Patients who received HD IL-2 and had already undergone a post-treatment scan were not eligible. Survival analysis was performed by the method of Kaplan and Meier using datasets as of July 27, 2015. Results: The overall response rate (ORR) and median overall survival (mOS) are described in Table 1. The mOS was not reached (NR) for 364 patients. The 1, 2 and 3 year survival rates were 79%, 63%, and 51%, respectively. For patients with stable disease (SD), the mOS was not reached and the 1, 2 and 3 year survival rates were 96%, 80%, and 60% respectively. There was a significant difference in mOS between SD and progressive disease (PD) patients, NR vs 15.5 months, P<.0001. The mOS was not reached for patients regardless of whether or not they received targeted therapy (TT) prior to HD IL-2. There were 4 reported treatment-related deaths in 364 patients (1.1%), none of these patients had prior TT. Conclusions: PROCLAIM data demonstrate that SD, previously grouped with the non-responders, is associated with extended survival rates. HD IL-2 is an active 2ndline treatment option for patients who have failed TT. These data support that HD IL-2 has a favorable safety profile and remains an effective therapy for eligible patients with mRCC. Clinical trial information: NCT01415167. [Table: see text]

Combination immunotherapy utilizing influenza infection and PD-1 blockade reduces lung melanoma tumor growth (TUM2P.1011)

Emerging epidemiological studies report increased cancer occurrence in patients with chronic viral infections, even when such infections are non-oncogenic and not in the same tissue as the cancer. In our recent studies, we observed decreased anti-tumor immune responses in the context of concomitant infection. Specifically, we discovered that anti-melanoma (gp100) CD8+ T cell responses in mice challenged with melanoma are shunted from the tumor site (skin) to the site of influenza infection (lung), leading to faster tumor growth and hastened host death. We observed similar findings with multiple tumor and virus combinations, including patient-derived melanomas in humanized mice infected with HIV. Based on this infection-mediated shunting of anti-tumor CD8+ T cells to the infection site, and towards developing related therapeutic interventions, we sought to determine whether an infection in a particular tissue would improve anti-tumor responses against a tumor also in that same tissue. We discovered that influenza infection within the lungs resulted in 51% fewer tumor foci within the lungs compared to no infection. Tumor foci were further reduced with systemic PD-1 blockade (more than 70% fewer tumor foci compared to no infection or PD-1 blockade alone). Future studies will further dissect the mechanisms underlying these findings in the setting of viral infection. We ultimately aim to translate these findings to combination cancer immunotherapies utilizing viral infections.

NK cells and CD8+ T cells cooperate to improve therapeutic responses in melanoma treated with CTLA-4 blockade and IL-2 (TUM2P.1039)

Immunotherapy is a promising approach for the treatment of metastatic melanoma and combination strategies may have potential for improving therapeutic responses. CTLA-4 blockade increases the CD8:Treg ratio in the tumor microenvironment and IL-2 promotes NK and CD8+ T cell function. Thus, we hypothesized combination IL-2 and CTLA-4 blockade would result in improved anti-tumor responses. This hypothesis was confirmed utilizing the poorly immunogenic B16 melanoma model, with CTLA-4 blocking antibody on days 3, 6, and 9 and/or IL-2 twice daily on days 4-8 after challenge, mirroring clinical use of these agents. Combination immunotherapy resulted in delayed tumor growth and prolonged survival compared to either monotherapy. Depletion studies suggested that both CD8+ T and NK cells were required for the therapeutic effects. In this model, combination treatment resulted in fewer tumor-infiltrating CD8+ T and NK cells but more infiltrating Tregs in the tumor microenvironment when compared to monotherapy CTLA-4 blockade. Further, IL-2 therapy was associated with a reduction in the proportion of highly differentiated/exhausted NK cells in the tumor microenvironment. No significant toxicity was observed in the mice. These results support the combination of IL-2 and CTLA-4 blockade in melanoma and a clinical trial based on these data has been initiated.

High dose (HD) IL-2 for metastatic renal cell carcinoma (mRCC) in the targeted therapy era: Extension of OS benefits beyond complete response (CR) and partial response (PR)

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Background: HD IL-2 has been reported to have a overall response rate (ORR) for mRCC of 15% and a median OS of 19 months (Fyfe, 1995), however, the studies that led to its regulatory approval are >15 years old and were performed in an era preceding targeted therapies. Methods: The PROCLAIM registry (www.proclaimregistry.com), a HD IL-2 observational database currently with over 30 participating sites, consists of a retrospective cohort (treated between 2007 and 2012) informing an ongoing prospective cohort (~600 patients). We report on the retrospective mRCC subjects (n=97, 13 sites) with survival status determined as of November 2013 and a median follow-up of 32 months. Sites were encouraged to enroll patients sequentially. Inclusion criteria required that patients have received at least one dose of HD IL-2. Results: The ORR was 22% (8% CR and 14% PR). Of 97 subjects, 36 were confirmed deceased and 61 were known to be alive, none were lost to follow-up. The median OS was 51 months, compared to a median OS range of 5-35 months for FDA-approved targeted agents (Harrison, 2013). There was significant clinical benefit in patients with CR, PR, and stable disease (SD), none of which reached median OS compared to 37.9 months in patients with progressive disease (PD). There is a significant advantage in PROCLAIM for those patients treated 1st vs. 2nd line HD IL-2; the median OS was 61.8 months (n=82) vs. 15.3 months (n=15), respectively. The clinical benefit of HD IL-2 therapy as front line is consistent with published data (Birkhauser, 2013). No deaths due to IL-2 related toxicity were reported in the retrospective cohort. Conclusions: The PROCLAIM registry documents a vastly improved OS for HD IL-2 compared to historical results during a time interval marked by the advent of targeted therapy for advanced RCC. Response to IL-2 (CR or PR) is associated with prolonged survival, however, stable disease as well as front line use also appears to positively impact survival. Issues including patient selection characteristics and treatment sequencing are hypotheses currently being explored in the prospective database. Clinical trial information: NCT01415167.