Katayoun I. Amiri

Augmenting Chemosensitivity of Malignant Melanoma Tumors via Proteasome Inhibition: Implication for Bortezomib (VELCADE, PS-341) as a Therapeutic Agent for Malignant Melanoma

Melanoma poses a great challenge to patients, oncologists, and biologists because of its nearly universal resistance to chemotherapy. Many studies have shown that nuclear factor κB is constitutively activated in melanoma, thereby promoting the proliferation of melanoma cells by inhibiting the apoptotic responses to chemotherapy. Nuclear factor κB activity is regulated by phosphorylation and subsequent degradation of inhibitor of nuclear factor κB by the ubiquitin-proteasome pathway. In this study, we show that the novel proteasome inhibitor, bortezomib, inhibited the growth of melanoma cells in vitro at a concentration range of 0.1–10 nm and in combination with the chemotherapeutic agent temozolomide, the inhibitory effect on melanoma cell growth was even more prominent. Data from a murine model showed reduced tumor growth when bortezomib was administered to human melanoma tumors. Strikingly, animals receiving bortezomib in combination with temozolomide achieved complete remission of palpable tumors after only 30 days of therapy, lasting >200 days. Our data indicate strongly that bortezomib in combination with chemotherapeutic agents should be studied additionally for the treatment of melanoma.

Role of nuclear factor-kappa B in melanoma.

Nuclear Factor-kappa B (NF-κ B) is an inducible transcription factor that regulates the expression of many genes involved in the immune response. Recently, NF-κ B activity has been shown to be upregulated in many cancers, including melanoma. Data indicate that the enhanced activation of NF-κ B may be due to deregulations in upstream signaling pathways such as Ras/Raf, PI3K/Akt, and NIK. Multiple studies have shown that NF-κ B is involved in the regulation of apoptosis, angiogenesis, and tumor cell invasion, all of which indicate the important role of NF-κ B in tumorigenesis. Thus, understanding the molecular mechanism of melanoma progression will aid in designing new therapeutic approaches for melanoma. In this review, the association between NF-κ B and melanoma tumorigenesis are discussed. Additionally, the potential of emerging selective NF-κ B inhibitors for the treatment of melanoma is reviewed.

BMS-345541 Targets Inhibitor of κB Kinase and Induces Apoptosis in Melanoma: Involvement of Nuclear Factor κB and Mitochondria Pathways

Purpose: Constitutive activation of inhibitor of κB kinase (IKK) confers melanoma resistance to apoptosis and chemotherapy. Whether IKK is able to serve as a therapeutic target in melanoma is unknown. We explored the possibility of exploiting IKK as a therapeutic target in melanoma by using BMS-345541, a novel compound with a highly selective IKKβ inhibitory activity, to trigger melanoma cell apoptosis. Experimental Design: Three human melanoma cell lines (SK-MEL-5, Hs 294T, and A375), all of which have high constitutive IKK activities, served as in vitro and in vivo melanoma models for treatment with BMS-345541. Two known antitumor drugs (temozolomide and bortezomib) were used as parallel controls for evaluation of the therapeutic efficiency and toxicity of BMS-345541. The effects of BMS-345541 on nuclear factor κB (NF-κB) signaling and on the apoptosis machinery were investigated. Results: Inhibition of constitutive IKK activity by BMS-345541 resulted in the reduction of NF-κB activity, CXCL1 chemokine secretion by cultured melanoma cells and melanoma cell survival in vitro and in vivo. The effect of BMS-345541 on tumor cell growth was through mitochondria-mediated apoptosis, based on the release of apoptosis-inducing factor, dissipation of mitochondrial membrane potential, and reduced ratio of B cell lymphoma gene-2 (Bcl-2)/Bcl-associated X protein (Bax) in mitochondria. The BMS-345541 execution of apoptosis was apoptosis-inducing factor–dependent, but largely caspase-independent. Conclusion: BMS-345541 down-regulation of IKK activity results in mitochondria-mediated apoptosis of tumor cells because the programmed cell death machinery in melanoma cells is highly regulated by NF-κB signaling. Therefore, IKK may serve as a potential target for melanoma therapy.

Targeting aurora kinases limits tumour growth through DNA damage-mediated senescence and blockade of NF-κB impairs this drug-induced senescence

Oncogene‐induced senescence can provide a protective mechanism against tumour progression. However, production of cytokines and growth factors by senescent cells may contribute to tumour development. Thus, it is unclear whether induction of senescence represents a viable therapeutic approach. Here, using a mouse model with orthotopic implantation of metastatic melanoma tumours taken from 19 patients, we observed that targeting aurora kinases with MLN8054/MLN8237 impaired mitosis, induced senescence and markedly blocked proliferation in patient tumour implants. Importantly, when a subset of tumour‐bearing mice were monitored for tumour progression after pausing MLN8054 treatment, 50% of the tumours did not progress over a 12‐month period. Mechanistic analyses revealed that inhibition of aurora kinases induced polyploidy and the ATM/Chk2 DNA damage response, which mediated senescence and a NF‐κB‐related, senescence‐associated secretory phenotype (SASP). Blockade of IKKβ/NF‐κB led to reversal of MLN8237‐induced senescence and SASP. Results demonstrate that removal of senescent tumour cells by infiltrating myeloid cells is crucial for inhibition of tumour re‐growth. Altogether, these data demonstrate that induction of senescence, coupled with immune surveillance, can limit melanoma growth.

RAF265 inhibits the growth of advanced human melanoma tumors.

Purpose: The purpose of this preclinical study was to determine the effectiveness of RAF265, a multikinase inhibitor, for treatment of human metastatic melanoma and to characterize traits associated with drug response. Experimental Design: Advanced metastatic melanoma tumors from 34 patients were orthotopically implanted to nude mice. Tumors that grew in mice (17 of 34) were evaluated for response to RAF265 (40 mg/kg, every day) over 30 days. The relation between patient characteristics, gene mutation profile, global gene expression profile, and RAF265 effects on tumor growth, mitogen-activated protein/extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK) phosphorylation, proliferation, and apoptosis markers was evaluated. Results: Nine of the 17 tumors that successfully implanted (53%) were mutant BRAF (BRAFV600E/K), whereas eight of 17 (47%) tumors were BRAF wild type (BRAFWT). Tumor implants from 7 of 17 patients (41%) responded to RAF265 treatment with more than 50% reduction in tumor growth. Five of the 7 (71%) responders were BRAFWT, of which 1 carried c-KITL576P and another N-RASQ61R mutation, while only 2 (29%) of the responding tumors were BRAFV600E/K. Gene expression microarray data from nonimplanted tumors revealed that responders exhibited enriched expression of genes involved in cell growth, proliferation, development, cell signaling, gene expression, and cancer pathways. Although response to RAF265 did not correlate with pERK1/2 reduction, RAF265 responders did exhibit reduced pMEK1, reduced proliferation based upon reduced Ki-67, cyclin D1 and polo-like kinase1 levels, and induction of the apoptosis mediator BCL2-like 11. Conclusions: Orthotopic implants of patient tumors in mice may predict prognosis and treatment response for melanoma patients. A subpopulation of human melanoma tumors responds to RAF265 and can be characterized by gene mutation and gene expression profiles. Clin Cancer Res; 18(8); 2184–98. ©2012 AACR.

Differential regulation of CXC ligand 1 transcription in melanoma cell lines by poly(ADP-ribose) polymerase-1.

The continuous production of the CXC ligand 1 (CXCL1) chemokine by melanoma cells is a major effector of tumor growth. We have previously shown that the constitutive expression of this chemokine is dependent upon transcription factors nuclear factor-kappa B (NF-κB), stimulating protein-1 (SP1), high-mobility group-I/Y (HMGI/Y), CAAT displacement protein (CDP) and poly(ADP-ribose) polymerase-1 (PARP-1). In this study, we demonstrate for the first time the mechanism of transcriptional regulation of CXCL1 through PARP-1 in melanoma cells. In its inactive state, PARP-1 binds to the CXCL1 promoter in a sequence-specific manner and prevents binding of NF-κB (p65/p50) to its element. However, activation of the PARP-1 enzymatic activity enhances CXCL1 expression, owing to the loss of PARP-1 binding to the CXCL1 promoter, accompanied by enhanced binding of p65 to the promoter. The delineation of the role of NF-κB-interacting factors in the putative CXCL1 enhanceosome will provide key information in developing strategies to block constitutive expression of this and other chemokines in cancer and to develop targeted therapy.

A Phase I Trial of Bortezomib with Temozolomide in Patients with Advanced Melanoma: Toxicities, Antitumor Effects, and Modulation of Therapeutic Targets

Purpose: Preclinical studies show that bortezomib, a proteasome inhibitor, blocks NF-κB activation and, combined with temozolomide, enhances activity against human melanoma xenografts and modulates other critical tumor targets. We initiated a phase I trial of temozolomide plus bortezomib in advanced melanoma. Objectives included defining a maximum tolerated dose for the combination, characterizing biomarker changes reflecting inhibition of both proteasome and NF-κB activity in blood (if possible tumor), and characterizing antitumor activity. Experimental Design: Cohorts were enrolled onto escalating dose levels of temozolomide (50-75 mg/m2) daily, orally, for 6 of 9 weeks and bortezomib (0.75-1.5 mg/m2) by i.v. push on days 1, 4, 8, and 11 every 21 days. Peripheral blood mononuclear cells were assayed at specified time points for proteasome inhibition and NF-κB biomarker activity. Results: Bortezomib (1.3 mg/m2) and temozolomide (75 mg/m2) proved to be the maximum tolerated dose. Dose-limiting toxicities included neurotoxicity, fatigue, diarrhea, and rash. Nineteen melanoma patients were enrolled onto four dose levels. This melanoma population (17 M1c, 10 elevated lactate dehydrogenase, 12 performance status 1-2) showed only one partial response (8 months) and three with stable disease ≥4 months. A significant reduction in proteasome-specific activity was observed 1 hour after infusion at all bortezomib doses. Changes in NF-κB electrophoretic mobility shift assay and circulating chemokines in blood failed to correlate with the schedule/dose of bortezomib, inhibition of proteasome activity, or clinical outcome. Conclusions: We have defined phase II doses for this schedule of temozolomide with bortezomib. Although proteasome activity was inhibited for a limited time in peripheral blood mononuclear cells, we were unable to show consistent effects on NF-κB activation. Clin Cancer Res; 16(1); 348–57

Fine Tuning the Transcriptional Regulation of the CXCL1 Chemokine

Constitutive activation of the transcription factor nuclear factor-κB (NF-κB) plays a major role in inflammatory diseases as well as cancer by inducing the endogenous expression of many proinflammatory proteins such as chemokines, and facilitating escape from apoptosis. The constitutive expression of chemokines such as CXCL1 has been correlated with growth, angiogenesis, and metastasis of cancers such as melanoma. The transcription of CXCL1 is regulated through interactions of NF-κB with other transcriptional regulatory molecules such as poly(ADP-ribose) polymerase-1 (PARP-1) and cAMP response element binding protein (CREB)-binding protein (CBP). It has been proposed that these two proteins interact with NF-κB and other enhancers to form an enhanceosome at the promoter region of CXCL1 and modulate CXCL1 transcription. In addition to these positive cofactors, a negative regulator, CAAT displacement protein (CDP), may also be involved in the transcriptional regulation of CXCL1. It has been postulated that the elevated expression of CXCL1 in melanomas is due to altered interaction between these molecules. CDP interaction with the promoter down-regulates transcription, whereas PARP and/or CBP interactions enhance transcription. Thus, elucidation of the interplay between components of the enhanceosome of this gene is important in finding more efficient and new therapies for conditions such as cancer as well as acute and chronic inflammatory diseases.

Quality of life (QoL) by response: An interim analysis of patients (pts) with squamous (SCC) NSCLC treated with nab-paclitaxel/carboplatin (nab-P/C) induction therapy in the phase III ABOUND.sqm study.

63 Background: The correlation of radiological response and pt-reported outcomes (PROs) in advanced NSCLC remains underreported. This interim analysis evaluated QoL by response (RECIST v1.1) in SCC NSCLC pts treated with nab-P/C during the induction part of the ABOUND.sqm study. METHODS In the ongoing phase III ABOUND.sqm study, pts with advanced SCC NSCLC are treated with first-line nab-P 100 mg/m2 d 1, 8, 15 and C AUC 6 mg•min/mL d 1 (21-d cycles) for 4 cycles (induction). Pts not progressing are randomized 2:1 to maintenance nab-P 100 mg/m2d 1 and 8 of each 21-d cycle + best supportive care (BSC) or BSC alone until progression. The primary endpoint is PFS from randomization to maintenance. QoL, an exploratory endpoint, was assessed with predefined PRO instruments, LCSS and EQ-5D-5L, on d 1 of each cycle. Pts with a radiological CR/ PR are considered responders (R) in this analysis (57% of evaluable pts). As the study is ongoing, this pre-planned analysis included QoL and tumor response data that were reported up to the cutoff date. RESULTS Baseline (BL) characteristics were similar for Rs (n = 73) and non-Rs (n = 55). Over 80% of pts completed BL + ≥ 1 post-BL PRO assessments. For LCSS, average total score and symptom burden index improved during induction chemotherapy; a higher percentage of Rs vs non-Rs had clinically meaningful improvements (≥ 10 mm [VAS]) from BL in composite LCSS cough, shortness of breath, & hemoptysis (56% vs 38%). Of pts reporting BL EQ-5D-5L dimension problem(s), a higher percentage of Rs vs non-Rs reported complete resolution at least once during treatment (Table). CONCLUSIONS These results indicate that Rs and non-Rs maintained/improved QoL during induction therapy with nab-P/C. Rs appeared to have greater improvements in LCSS and EQ-5D-5L. Radiological response translates into meaningful QoL improvement. CLINICAL TRIAL INFORMATION NCT02027428. [Table: see text].

nab-Paclitaxel-Based Therapy in Underserved Patient Populations: The ABOUND.70+ Study in Elderly Patients With Advanced NSCLC

The phase 4 ABOUND.70+ trial assessed the safety and efficacy of nab-paclitaxel/carboplatin continuously or with a 1-week break between cycles in elderly patients with advanced non-small cell lung cancer (NSCLC). Patients ≥70 years with locally advanced/metastatic NSCLC were randomized 1:1 to first-line nab-paclitaxel days 1, 8, 15 plus carboplatin day 1 of a 21-day cycle (21d) or the same nab-paclitaxel/carboplatin regimen with a 1-week break between cycles (21d + break; 28d). The primary endpoint was the percentage of patients with grade ≥ 2 peripheral neuropathy (PN) or grade ≥ 3 myelosuppression. Other key endpoints included progression-free survival (PFS), overall survival (OS), and overall response rate (ORR). A total of 143 patients were randomized (71 to 21d, 72 to 21d + break). The percentage of patients with grade ≥ 2 PN or grade ≥ 3 myelosuppression was similar between the 21d and 21d + break arms (76.5 and 77.1%; P = 0.9258). Treatment exposure was lower in the 21d arm compared with the 21d + break arm. Median OS was 15.2 and 16.2 months [hazard ratio (HR) 0.72, 95% CI 0.44–1.19; P = 0.1966], median PFS was 3.6 and 7.0 months (HR 0.48, 95% CI 0.30–0.76; P < 0.0019), and ORR was 23.9 and 40.3% (risk ratio 1.68, 95% CI 1.02–2.78; P = 0.0376) in the 21d and 21d + break arms, respectively. In summary, the 1-week break between treatment cycles significantly improved PFS and ORR but did not significantly reduce the percentage of grade ≥ 2 PN or grade ≥ 3 myelosuppression. Overall, the findings support the results of prior subset analyses on the safety and efficacy of first-line nab-paclitaxel/carboplatin in elderly patients with advanced NSCLC.