Abstract 2900: IMCgp100: A novel bi-specific biologic for the treatment of malignant melanoma

Despite significant advances in the treatment of metastatic melanoma, long-term remission for the majority of patients remains elusive. Kinase inhibitors provide potent but short-term responses for a significant proportion of patients and immunotherapy elicits long-term responses with the prospect of cure, but only in a minority.

IMCgp100 is a novel bi-specific immunotherapy comprising a soluble, affinity enhanced, T cell receptor (TCR) specific for the melanoma-associated antigen gp100, fused to an anti-CD3 specific antibody fragment (scFv). The engineered TCR portion of the drug targets and binds the gp100 peptide 280-288 antigen, which is over-expressed and presented by HLA-A2 on the surface of melanoma cells. The anti-CD3 scFv portion captures and redirects T cells to kill the melanoma cells, while normal antigen negative tissues are unaffected. Here, we present data which provides the foundation for the clinical observations. In vitro, IMCgp100 is demonstrated to potently redirect T cells from late stage cancer patients to target melanoma tumors exhibiting HLA-down regulation, even in the presence of high numbers of regulatory T cells. Target cell killing is observed within hours and is specific for gp100. In addition killing is associated with the release of various pro-inflammatory cytokines and chemokines as well as cross-presentation of gp100 and other melanoma-associated antigens by dendritic cells. Thus, IMCgp100 demonstrates the potential to elicit potent short-term responses and trigger longer-term anti melanoma activity in vivo.

IMCgp100 is undergoing Phase I clinical testing in patients with advanced malignant melanoma; with the maximum tolerated dose having been established. The drug is well tolerated with evidence of tumor shrinkage. Analyses of serum samples obtained from patients on the trial demonstrate T cell mobilisation and transient drug mediated increases in various cytokines and chemokines, some of which are reported to play a key role in anti-melanoma responses. These data support the potential of IMCgp100 as an effective treatment for malignant melanoma.

Citation Format: Namir J. Hassan, Giovanna Bossi, Debbie Baker, Katherine Adams, Jane Harper, Joseph Dukes, Nathaniel Liddy, Samantha Paston, Yvonne McGrath, Tara Mahon, Peter Molloy, Malkit Sami, Emma Baston, Brian Cameron, Andrew Johnson, Annelise Vuidepot, Gerry Linette, Michael Kalos, Carl June, Bent Jakobsen. IMCgp100: A novel bi-specific biologic for the treatment of malignant melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2900. doi:10.1158/1538-7445.AM2014-2900

Abstract 3170: Identification of novel genetic alterations driving melanoma tumorigenesis

Recent high-throughput sequencing efforts have provided a comprehensive view of cancer genomes, revealing their complexity and heterogeneity. However, most of these studies remain descriptive without further functional and clinical validation of the candidate alterations, mainly due to the overwhelming number of somatic alterations present. To discover novel driver mutations of melanoma, massively parallel whole genome sequencing (WGS) was used to characterize 15 metastatic melanomas derived from 13 patients. A large number of somatic alterations were discovered in these tumors and hybridization capture-based validation confirmed 17,361 tier 1 point mutations, 84 tier 1 indels, and 411 somatic structural variants. As a pilot study to exploit this genomic data in order to identify novel genetic alterations driving melanoma tumorigenesis, we performed mutation proximity analysis to select candidates for further analysis. In this study, we addressed possible roles of DBC1 (Deleted in Bladder Cancer 1) and RASA1 (RAS p21 protein activator 1), which showed previously undocumented neighboring mutations. RASA1 is a GTPase activation protein that acts as a suppressor of RAS function. RASA1 has been implicated in actin filament polymerization, vascular development, cellular apoptosis, and cell motility. Our whole-genome analyses of melanomas identified two somatic missense mutations, targeting highly conserved neighboring Y472 and L481 in or around the PH domain in RASA1 in two samples. DBC1, also called BRINP, DBCCR1, and FAM5A, was previously shown to undergo loss of heterozygosity at 9q32-q33 in bladder cancer, and methylation silencing in bladder, breast, and lung cancers. Ectopic expression of DBC1 in bladder and lung cancer cells was reported to cause cell death and to inhibit cell proliferation, respectively. We observed six DBC1 missense mutations by whole genome analyses in four patients, including 2 neighboring mutations targeting S688 and S690. The shRNA-mediated knock down of DBC1 and RASA1 in melanocyte derived from Ink4a/Arf deletion/BRAF mutation background promoted proliferation, soft agar colony formation, and invasion. Ectopic expression of wild type DBC1 and RASA1 in human melanoma cell lines SKmel28 and WM983C (all with BRAFV600E), respectively, decreased soft agar colony formation, supporting their tumor suppressive roles. Various mutant forms of RASA1 and DBC1 were addressed for their roles. Interestingly, loss of RASA1 conferred decreased sensitivity to BRAF inhibitor Vemurafenib. In order to address the mutation frequency of DBC1 and RASA1, we analyzed additional melanoma samples and observed mutation rates of 21% for DBC1 (20/96 patients) and 9% for RASA1 (20/221). Therefore, our findings support that DBC1 and RASA1 play roles in melanoma suppression and the utility of genomic data for the identification of novel genes involved in tumorigenesis.

Citation Format: Minjung Kim, Li Ding, Nathan Dees, Krishna L. Kanchi, Hyeran Sung, David Fenstermacher, Malachi Griffith, Gerry Linette, Lynn Cornelius, Vernon K. Sondak, James J. Mulé, Richard K. Wilson, Jeffrey S. Weber. Identification of novel genetic alterations driving melanoma tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3170. doi:10.1158/1538-7445.AM2013-3170

Efficacy of ipilimumab 10 mg/kg in advanced melanoma patients (pts) with good and poor prognostic factors

9036

Background: Ipilimumab is a fully human monoclonal antibody against cytotoxic T-lymphocyte antigen-4. In total, ∼50% of metastatic melanoma pts treated with 10 mg/kg ipilimumab are alive at 1 year (Wolchok et al. CRI-CVC annual meeting 2008. Oral presentation), and identifying prognostic factors may help select pts most likely to benefit from treatment. Factors predictive of poorer prognosis in melanoma include advanced stage of disease (ie, M1c), age 60+, gender (male), elevated baseline lactate dehydrogenase (LDH) levels, and lack of a prior response to therapy. In this pooled analysis, potential prognostic factors in pts with advanced melanoma treated with ipilimumab 10 mg/kg in 2 phase II studies (CA184–008, N=155 and -022, N=72) were explored. Methods: Ipilimumab 10 mg/kg was given every 3 weeks (Q3W) × 4 (induction); eligible pts could continue to receive ipilimumab Q12W starting at week (Wk) 24 (maintenance). Response was based on modified World Health Organization criteria. Each variable was analyzed separately. Results: Disease control rate (complete/partial response [CR/PR] and stable disease) seems not to be associated with age (<65 yrs: 25.2%; ≥65 yrs: 32.9%), gender (male: 22.6%; female: 34.0%), M stage (M0: 33.3%; M1a: 41.0%; M1b: 26.4%; M1c: 23.6%), response to prior systemic therapy (yes: 32.5%; no: 26.7%), prior immunotherapy (yes: 21.6%; no: 35.3%), LDH >upper normal limit (UNL) (yes: 25.9%; no: 29.7%), or LDH >2×UNL (yes: 15.9%; no: 30.6%). Best overall response rate (CR or PR) was not associated with age (<65 yrs: 7.3%; ≥65 yrs: 7.9%), gender (male: 4.0%; female: 11.7%), M stage (M0: 8.3%; M1a: 15.4%; M1b: 5.7%; M1c: 5.7%), response to prior systemic therapy (yes: 12.5%; no: 6.4%), prior immunotherapy (yes: 3.2%; no: 12.7%), LDH >UNL (yes: 8.6%; no: 6.3%), or LDH >2×UNL (yes: 4.5%; no: 8.2%). Overall survival was not associated with age (median OS: <65 yrs: 11.6 mo; ≥65 yrs: 7.59 mo), M stage (median OS: M0: 21.9 mo; M1a: 15.7 mo; M1b: 15.4 mo; M1c: 6.6 mo), or response to prior systemic therapy (median OS: yes: 11.6 mo; no: 10.7 mo). Conclusions: Ipilimumab demonstrates clinical activity independent of negative prognostic factors, and may even benefit those pts with the worst prognosis.

[Table: see text]

Association between immune-related adverse events (irAEs) and disease control or overall survival in patients (pts) with advanced melanoma treated with 10 mg/kg ipilimumab in three phase II clinical trials

9034

Background: The monoclonal antibody ipilimumab targets cytotoxic T-lymphocyte antigen-4. The most common AEs associated with ipilimumab are irAEs, and both antitumor and irAE responses likely reflect its immune-mediated mechanism of action. In this report, a potential association between disease control (DC) or overall survival (OS) and irAEs in patients (pts) with advanced melanoma treated with 10 mg/kg ipilimumab in 3 Phase II clinical trials was explored. Methods: Across 3 Phase II studies (CA184008, 022, and 007), ipilimumab (10 mg/kg) was given every 3 weeks (Q3W) x 4 (induction); eligible pts could continue to receive ipilimumab Q12W starting at week (wk) 24 (maintenance). In study 022, pts were randomized to 0.3, 3, and 10 mg/kg groups, whereas study 008 was a single-arm trial of ipilimumab 10 mg/kg. In study 007, ipilimumab 10 mg/kg was administered either with placebo or daily prophylactic budesonide. Disease control (CR/PR/SD) was evaluated using modified World Health Organization (mWHO) and immune- related response criteria (Hodi FS, et al. J Clin Oncol 26: 2008 (May 20 suppl; abstr 3008). Association between DC and grade 0/1 vs. grade ≥2 irAEs was examined (studies 007, 008, and 022). Association between OS and irAEs which developed within 12 wks of ipilimumab treatment was also explored using landmark analyses from Day 81 (studies 008 and 022). Results: Across the 3 phase II studies, the rate of DC by mWHO in pts with grade 0/1 irAEs was 20–24% and in pts with grade ≥2 irAEs was 34–43%. The number of pts with DC was higher among those who experienced an irAE compared with those who did not, but DC was not statistically significantly associated with grade 0/1 vs grade ≥2 irAEs. For pts who lived up to Day 81 in studies 008 and 022, median OS (95% CI) from Day 81 was 14.8 mo (10.0–21.7) for any irAE and 8.21 mo (5.29–13.7) for no irAE within 12 weeks; median OS was 13.6 mo (5.78-NR) for any grade ≥2 irAE and 11.3 mo (7.95–15.8) for no grade ≥2 irAE within 12 weeks. Conclusions: DC and survival benefits with ipilimumab are observed among pts that develop an irAE and among pts that do not develop an irAE. Thus, pts who do not experience an irAE may still demonstrate clinical benefit with ipilimumab.

[Table: see text]

Randomized phase II study of dacarbazine with or without sorafenib in patients with advanced melanoma

8511

Background: Sorafenib (SOR), a potent and selective multi-kinase inhibitor, exerts its anti-tumor and anti-angiogenic effects via inhibition of VEGFR-1, -2, -3, PDGFR-a, -β, and Raf. Dacarbazine (DTIC) is an FDA-approved cytotoxic agent for advanced melanoma. Phase I/II results of SOR + DTIC were encouraging and prompted this randomized phase II study. Methods: This was a multi- center, double-blinded, placebo-controlled study; eligibility criteria included measurable disease by RECIST, no prior cytotoxic chemotherapy, and no active brain metastases. Advanced melanoma patients (pts) stratified by stage (unresectable III vs IVM1a/M1b vs M1c) and ECOG PS (0 vs 1) were randomized to receive DTIC 1,000 mg/m2 q 21 days + oral placebo (PL) or oral SOR 400 mg bid continuously until the occurrence of progressive disease or intolerable toxicity. The primary endpoint was progression-free survival (PFS) of DTIC+SOR vs DTIC+PL. Using a two-sided test with a = 0.05, 77 PFS events were needed to detect a hazard ratio (HR) of 0.5 (SOR/PL) with 86 % power. The secondary endpoint was overall survival and tertiary endpoints were objective response rate (ORR), time to progression, and duration of response. Results: 101 pts were enrolled over 12 months (51 DTIC+SOR, 50 DTIC+PL). Treatment arms were balanced for age (median 58 yrs), gender (male 70%), PS (ECOG 1 39%), stage (Stage IV M1c 52%) and baseline LDH (>ULN 29%). At the time of analysis by independent assessment, the median PFS of DTIC+PL vs DTIC+SOR was 11.7 wks (95% CI 6.1, 17.9) vs 21.1 wks (95% CI: 16, 28); HR 0.67 [p=0.07]; PFS rate at Day 180 was 18% vs 41%; and ORR was 12% vs 24%. Survival data are immature. Toxicities of Grade 3 or higher (DTIC+PL vs DTIC+SOR) included neutropenia (12% vs 33%), leukopenia (6% vs 14%), thrombocytopenia (18% vs 35%), thrombosis/embolism (0% vs 6%), hypertension (0 vs 8%), hand-foot skin reaction (0 vs 4%), and CNS hemorrhage (0% vs 8%). 3 of the 4 pts with CNS hemorrhage had new brain metastases. No treatment-related deaths occurred in either arm. Conclusions: DTIC+SOR was well tolerated and showed a strong efficacy trend compared with DTIC+PL in median PFS, PFS rate at 6 months and ORR in chemotherapy-naïve pts with advanced melanoma. This regimen warrants further evaluation in larger clinical trial settings.

No significant financial relationships to disclose.

Phase II study of the farnesyltransferase inhibitor R115777 in advanced melanoma: CALGB 500104

8014

Background: Ras-based signaling is thought to be critical in the genesis of melanoma. Farneslytransferase (FT) inhibitors (FTIs) have been developed as a pharmacologic strategy to inhibit Ras function. Additional farnesylated proteins are also important for the malignant process, and FTIs inhibit melanoma cell line proliferation in vitro. These considerations motivated the development of a phase II trial of the FTI R115777 in patients with melanoma. Farnesylated proteins are also important for T cell activation. The interest in future combinations of targeted agents and immunotherapeutics in this disease prompted analysis of T cell function ex vivo. Methods: A 3-stage design was pursued with a maximum of 40 patients planned and early stopping if there were no responders in the first 14, or fewer than 2 responders in the first 28 patients. Eligibility included intact organ function, PS≤1, no prior chemotherapy, at most 1 prior immunotherapy, no brain metastases, and presence of at least 2 cutaneous lesions amenable to excisional biopsy. R115777 (300 mg orally) was administered twice per day for 21 days of a 28-day cycle. Patients were evaluated every 2 cycles by RECIST criteria. Blood was obtained pre-treatment and during week 7 for analysis of HDJ-2 farnesylation and for T cell IFN-γ production in response to SEA. In addition, tumor biopsies were performed pre- and post-treatment when feasible to directly measure FT activity. Results: 14 patients were enrolled. 2 patients had grade 3 toxicities, which included myelosuppression, nausea/vomiting, elevated BUN, and anorexia. There were no clinical responses, and only 4 patients went on to a second course of treatment. All analyzed patients showed HDJ-2 gel shift in peripheral blood cells, as well as marked inhibition of FT activity (by 85–98%) in tumor tissue. T cell production of IFN-γ was also suppressed. Conclusions: Despite potent target inhibition, the FTI R115777 showed no evidence for clinical activity as a single agent in this cohort of 14 metastatic melanoma patients. Inhibition of T cell function has implications for future combination therapies and suggests the possibility for FTIs as candidate immunosuppressive agents. New therapeutic approaches for melanoma, or logically selected combination therapies, are needed.

[Table: see text]

Disinfection of Goldmann tonometers against human immunodeficiency virus type 1

Goldmann tonometer tips were inoculated with 5 X 10(5) IU of cell-free or cell-associated human immunodeficiency virus type 1 (lymphadenopathy virus type 1 isolate) or 10(4) plaque-forming units of herpes simplex virus type 1 (McKrae strain) or type 2 (Hicks strain). In an effort to mimic a "worst case" clinical scenario, each respective virus was allowed to air dry on the tonometer tip for 10 minutes. Inoculated tonometers were then (1) not treated, (2) wiped with a disposable (Kim-wipe) tissue or sterile gauze; (3) wiped with sterile gauze soaked with 3% hydrogen peroxide; or (4) wiped with a 70% isopropyl alcohol swab. The hydrogen peroxide treatment and the alcohol wipes both completely disinfected the tonometer tips for human immunodeficiency virus type 1 and herpes simplex virus types 1 and 2, whereas wiping with a sterile gauze or tissue was not effective. Wiping the Goldmann tonometer tip with an isopropyl alcohol swab and then allowing the alcohol to evaporate provides a ready and efficient means of inactivating these three enveloped viruses.

The immunologic response of congenitally athymic rats to Schistosoma mansoni infection. I. In vivo studies of resistance

The responses of congenitally athymic (Nu/Nu) rats to an initial exposure and to re-exposure to Schistosoma mansoni were compared to those manifested by thymic reconstituted (Nu/Nu*TxR), heterozygous littermate controls (Nu/+) and the highly characterized Fischer rat strain. Congenitally athymic rats rejected the developing worms of an initial infection more slowly than did thymic reconstituted or heterozygous animals. These latter responses were highly comparable to those demonstrated by the Fischer rat. In addition, the congenitally athymic rats manifested lower peripheral blood eosinophilia in response to infection. Resistance to reinfection in athymic animals was impaired and associated with a decreased immunoinflammatory histologic response to hepatic intravascular parasites and to eggs lodged in the hepatic vasculature. There was little evidence of inflammatory responses involving degranulating eosinophils, lymphocytes, or macrophages in the athymic rats. Finally, athymic animals produced antibody that was less capable of passively transferring resistance in adoptive-challenge experiments; however, antibody produced in heterozygous animals conferred significant resistance when adoptively transferred to athymic animals. These results suggest that resistance to initial and subsequent challenge by S. mansoni infections in the rat is highly reliant upon T-dependent mechanisms that result in the production of antibody-dependent, possibly cell-mediated resistance. Additional studies utilizing in vitro analysis of a variety of antibody functions to define the mechanisms of T-dependent immunologic resistance in the congenitally athymic rat are the subject of the accompanying manuscript.

The immunologic response of congenitally athymic rats to Schistosoma mansoni infection. I. In vivo studies of resistance

The responses of congenitally athymic (Nu/Nu) rats to an initial exposure and to re-exposure to Schistosoma mansoni were compared to those manifested by thymic reconstituted (Nu/Nu*TxR), heterozygous littermate controls (Nu/+) and the highly characterized Fischer rat strain. Congenitally athymic rats rejected the developing worms of an initial infection more slowly than did thymic reconstituted or heterozygous animals. These latter responses were highly comparable to those demonstrated by the Fischer rat. In addition, the congenitally athymic rats manifested lower peripheral blood eosinophilia in response to infection. Resistance to reinfection in athymic animals was impaired and associated with a decreased immunoinflammatory histologic response to hepatic intravascular parasites and to eggs lodged in the hepatic vasculature. There was little evidence of inflammatory responses involving degranulating eosinophils, lymphocytes, or macrophages in the athymic rats. Finally, athymic animals produced antibody that was less capable of passively transferring resistance in adoptive-challenge experiments; however, antibody produced in heterozygous animals conferred significant resistance when adoptively transferred to athymic animals. These results suggest that resistance to initial and subsequent challenge by S. mansoni infections in the rat is highly reliant upon T-dependent mechanisms that result in the production of antibody-dependent, possibly cell-mediated resistance. Additional studies utilizing in vitro analysis of a variety of antibody functions to define the mechanisms of T-dependent immunologic resistance in the congenitally athymic rat are the subject of the accompanying manuscript.