A plain language summary of the PHAROS study: the combination of encorafenib and binimetinib for people with BRAF V600E-mutant metastatic non-small cell lung cancer

WHAT IS THIS SUMMARY ABOUT?

This is a summary of the results of a study called PHAROS. This study looked at combination treatment with encorafenib (BRAFTOVI®) and binimetinib (MEKTOVI®). This combination of medicines was studied in people with metastatic non-small-cell lung cancer (NSCLC). NSCLC is the most common type of lung cancer. Metastatic means that the cancer has spread to other parts of the body. All people in this study had a type of NSCLC that has a change in a gene called BRAF termed a BRAF V600E mutation. A gene is a part of the DNA that has instructions for making things that your body needs to work, and the BRAF V600E mutation contributes to the growth of the lung cancer.

WHAT WERE THE RESULTS?

In this study, 98 people with BRAF V600E-mutant metastatic NSCLC were treated with the combination of encorafenib and binimetinib (called encorafenib plus binimetinib in this summary). Before starting the study, 59 people had not received any treatment for their metastatic NSCLC, and 39 people had received previous anticancer treatment. At the time of this analysis, 44 (75%) out of 59 people who did not receive any treatment before taking encorafenib plus binimetinib had their tumors shrink or disappear. Eighteen (46%) out of 39 people who had received treatment before starting encorafenib plus binimetinib also had their tumors shrink or disappear. The most common side effects of encorafenib plus binimetinib were nausea, diarrhea, fatigue, and vomiting.

WHAT DO THE RESULTS MEAN?

These results support the use of encorafenib plus binimetinib combination treatment as a new treatment option in people with BRAF V600E-mutant metastatic NSCLC. The side effects of encorafenib plus binimetinib in this study were similar to the side effects seen with encorafenib plus binimetinib in people with a type of skin cancer called metastatic melanoma.

Avelumab or talazoparib in combination with binimetinib in metastatic pancreatic ductal adenocarcinoma: dose-finding results from phase Ib of the JAVELIN PARP MEKi trial

BACKGROUND

Combinations of avelumab [anti-programmed death-ligand 1 (anti-PD-L1)] or talazoparib [poly(adenosine diphosphate ribose) polymerase (PARP) inhibitor] with binimetinib (MEK inhibitor) were expected to result in additive or synergistic antitumor activity relative to each drug administered alone. Here, we report phase Ib results from JAVELIN PARP MEKi, which investigated avelumab or talazoparib combined with binimetinib in metastatic pancreatic ductal adenocarcinoma (mPDAC).

PATIENTS AND METHODS

Patients with mPDAC that had progressed with prior treatment received avelumab 800 mg every 2 weeks plus binimetinib 45 mg or 30 mg two times daily (continuous), or talazoparib 0.75 mg daily plus binimetinib 45 mg or 30 mg two times daily (7 days on/7 days off). The primary endpoint was dose-limiting toxicity (DLT).

RESULTS

A total of 22 patients received avelumab plus binimetinib 45 mg (n = 12) or 30 mg (n = 10). Among DLT-evaluable patients, DLT occurred in five of 11 patients (45.5%) at the 45-mg dose, necessitating de-escalation to 30 mg; DLT occurred in three of 10 patients (30.0%) at the 30-mg dose. Among patients treated at the 45-mg dose, one (8.3%) had a best overall response of partial response. Thirteen patients received talazoparib plus binimetinib 45 mg (n = 6) or 30 mg (n = 7). Among DLT-evaluable patients, DLT occurred in two of five patients (40.0%) at the 45-mg dose, necessitating de-escalation to 30 mg; DLT occurred in two of six patients (33.3%) at the 30-mg dose. No objective responses were observed.

CONCLUSIONS

Combinations of avelumab or talazoparib plus binimetinib resulted in higher-than-expected DLT rates. However, most DLTs were single occurrences, and the overall safety profiles were generally consistent with those reported for the single agents.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.govNCT03637491; https://clinicaltrials.gov/ct2/show/NCT03637491.

Phase II, Open-Label Study of Encorafenib Plus Binimetinib in Patients With BRAFV600-Mutant Metastatic Non-Small-Cell Lung Cancer

PURPOSE

The combination of encorafenib (BRAF inhibitor) plus binimetinib (MEK inhibitor) has demonstrated clinical efficacy with an acceptable safety profile in patients with BRAFV600E/K-mutant metastatic melanoma. We evaluated the efficacy and safety of encorafenib plus binimetinib in patients with BRAFV600E-mutant metastatic non-small-cell lung cancer (NSCLC).

METHODS

In this ongoing, open-label, single-arm, phase II study, patients with BRAFV600E-mutant metastatic NSCLC received oral encorafenib 450 mg once daily plus binimetinib 45 mg twice daily in 28-day cycles. The primary end point was confirmed objective response rate (ORR) by independent radiology review (IRR). Secondary end points included duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival, time to response, and safety.

RESULTS

At data cutoff, 98 patients (59 treatment-naïve and 39 previously treated) with BRAFV600E-mutant metastatic NSCLC received encorafenib plus binimetinib. Median duration of treatment was 9.2 months with encorafenib and 8.4 months with binimetinib. ORR by IRR was 75% (95% CI, 62 to 85) in treatment-naïve and 46% (95% CI, 30 to 63) in previously treated patients; median DOR was not estimable (NE; 95% CI, 23.1 to NE) and 16.7 months (95% CI, 7.4 to NE), respectively. DCR after 24 weeks was 64% in treatment-naïve and 41% in previously treated patients. Median PFS was NE (95% CI, 15.7 to NE) in treatment-naïve and 9.3 months (95% CI, 6.2 to NE) in previously treated patients. The most frequent treatment-related adverse events (TRAEs) were nausea (50%), diarrhea (43%), and fatigue (32%). TRAEs led to dose reductions in 24 (24%) and permanent discontinuation of encorafenib plus binimetinib in 15 (15%) patients. One grade 5 TRAE of intracranial hemorrhage was reported. Interactive visualization of the data presented in this article is available at the PHAROS dashboard (https://clinical-trials.dimensions.ai/pharos/).

CONCLUSION

For patients with treatment-naïve and previously treated BRAFV600E-mutant metastatic NSCLC, encorafenib plus binimetinib showed a meaningful clinical benefit with a safety profile consistent with that observed in the approved indication in melanoma.

A Phase 1B open-label study of gedatolisib (PF-05212384) in combination with other anti-tumour agents for patients with advanced solid tumours and triple-negative breast cancer

BACKGROUND

This Phase 1b study (B2151002) evaluated the PI3K/mTOR inhibitor gedatolisib (PF-05212384) in combination with other anti-tumour agents in advanced solid tumours.

METHODS

Patients with various malignancies were administered gedatolisib (90‒310 mg intravenously every week [QW]) plus docetaxel (arm A) or cisplatin (arm B) (each 75 mg/m2 intravenously Q3W) or dacomitinib (30 or 45 mg/day orally). The safety and tolerability of combination therapies were assessed during dose escalation; objective response (OR) and safety were assessed during dose expansion.

RESULTS

Of 110 patients enrolled, 107 received gedatolisib combination treatment. Seven of 70 (10.0%) evaluable patients had dose-limiting toxicities; the most common was grade 3 oral mucositis (n = 3). Based upon reprioritisation of the sponsor's portfolio, dose expansion focused on arm B, gedatolisib (180 mg QW) plus cisplatin in patients (N = 22) with triple-negative breast cancer (TNBC). OR (95% CI) was achieved in four of ten patients in first-line (overall response rate 40.0% [12.2-73.8%]) and four of 12 in second/third-line (33.3% [9.9-65.1%]) settings. One patient in each TNBC arm (10%, first-line; 8.3%, second/third-line) achieved a complete response.

CONCLUSIONS

Gedatolisib combination therapy showed an acceptable tolerability profile, with clinical activity at the recommended Phase 2 dose in patients with TNBC.

CLINICAL TRIAL

ClinicalTrial.gov: NCT01920061.

Abstract 6403: Molecular correlates of clinical benefit from circulating tumor DNA (ctDNA): Analysis of the COLUMBUS study

Background: In the randomized, two-part, phase 3 COLUMBUS study (NCT01909453), encorafenib (enco) + binimetinib (bini) and enco alone improved 5-year progression-free survival (PFS) and overall survival (OS) vs vemurafenib (vem) in patients (pts) with advanced BRAF V600E/K-mutant melanoma. ctDNA offers a less invasive alternative to tissue biopsy for identifying mutations in pts with advanced melanoma and may have prognostic value. We evaluated whether ctDNA from pts enrolled in COLUMBUS Part 1 correlate with pts’ efficacy outcomes.

Methods: In COLUMBUS Part 1, 577 pts were randomized 1:1:1 to enco + bini, enco, or vem. 650 plasma samples were collected at baseline (Cycle 0 or Cycle 1 Day 1; all arms) and during treatment (Cycle 2 Day 1 [C2D1]; enco + bini and enco arms); 426 samples from COLUMBUS Part 1 were successfully analyzed using the GuardantOMNI assay. Analyses were exploratory with no multiplicity adjustments.

Results: Survival outcomes in the biomarker cohort were similar to those in the intent-to-treat population. ctDNA was detected in 279 (96%) pts at baseline and 107 (79%) pts at C2D1. 92% concordance was observed between two plasma genomics assays (Inostics and Guardant) and 75% between tumor and plasma with respect to BRAF mutation status. BRAF V600 variant allele frequency (VAF) at baseline was prognostic for PFS and OS (P<0.0001) in the enco + bini arm. Treatment with enco + bini and enco sharply reduced BRAF V600 VAF (P<0.0001). Decrease in BRAF V600 VAF was more pronounced in responders than in non-responders. Greater clinical benefit was observed in pts with complete ctDNA clearance at C2D1, among whom 12% and 58% had a complete or partial response, respectively, vs 9% and 48%, respectively, for those without complete ctDNA clearance. In the enco + bini arm, high tumor mutational burden (≥10 per megabase) at C2D1, but not at baseline, was associated with shorter PFS (P<0.0001) and OS (P=0.0151). The most frequently detected alterations at baseline were BRAF (79%), TERT (53%), LRP1B (21%), TP53 (17%), and PREX2 (14%). BRAF gene had the most significant decrease from baseline to C2D1 (51.6% difference; P<0.0001), followed by TERT (41.6% difference; P<0.0001), GRIN2A (16.3% difference; P=0.0152), and ROS1 (12.2% difference; P=0.0437) in pts who received enco + bini. FGFR1 mutations were found to be most associated with a lack of BRAF V600 clearance (P=0.0005). Further analyses of molecular correlates of response and resistance are underway.

Conclusions: These exploratory analyses of Part 1 of the COLUMBUS study suggested that treatment with enco + bini significantly reduced BRAF V600 VAF, which was prognostic for PFS and OS at both baseline and C2D1. ctDNA provides a powerful tool for understanding the molecular basis for response and resistance to treatment and may impact future treatment decisions.

Citation Format: Reinhard Dummer, Nuzhat Pathan, Zhou Zhu, Caroline Robert, Ana Arance, Jan Willem B. de Groot, Claus Garbe, Helen J. Gogas, Ralf Gutzmer, Ivana Krajsová, Gabriella Liszkay, Carmen Loquai, Mario Mandala, Dirk Schadendorf, Naoya Yamazaki, Michelle Edwards, Jean Cantey-Kiser, Alessandra di Pietro, Shibing Deng, Paolo A. Ascierto, Keith Flaherty. Molecular correlates of clinical benefit from circulating tumor DNA (ctDNA): Analysis of the COLUMBUS study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6403.

A phase 1b/2 study of PF-06747775 as monotherapy or in combination with Palbociclib in patients with epidermal growth factor receptor mutant advanced non-small cell lung cancer

INTRODUCTION

This Phase 1/2 study (NCT02349633) explored the safety and antitumor activity of PF-06747775 (oral, third-generation epidermal growth factor receptor [EGFR] tyrosine kinase inhibitor) in patients with advanced non-small cell lung cancer after progression on an EGFR inhibitor.

METHODS

Phase 1 was a dose-escalation study of PF-06747775 monotherapy (starting dose: 25 mg once daily [QD]). Phase 1b/2 evaluated PF-06747775 monotherapy at recommended Phase 2 dose (RP2D; Cohort 1); PF-06747775 200 mg QD plus palbociclib (starting dose: 100 mg QD orally; Cohort 2A); and PF-06747775 monotherapy at RP2D in a Japanese lead-in cohort.

RESULTS

Sixty-five patients were treated. Median treatment duration was 40.1 weeks. Monotherapy maximum tolerated dose was not determined. Two patients in Cohort 2A had dose-limiting toxicities. The monotherapy RP2D was estimated to be 200 mg QD. Most frequently reported adverse events (AEs) were diarrhea (69.2%), paronychia (69.2%), and rash (60.0%). Most AEs were grades 1-3. Overall, objective response rate (90% confidence interval [CI]) was 41.5% (31.2-52.5%). Median (range) duration of response was 11.09 (2.70-34.57) months. Median progression-free survival (90% CI) was 8.1 (5.4-23.3) months.

CONCLUSIONS

PF-06747775 had a manageable safety profile and the study design highlights important considerations for future anti-EGFR agent development.

344 Avelumab + binimetinib in metastatic pancreatic ductal adenocarcinoma (mPDAC): dose-escalation results from the phase 1b/2 JAVELIN PARP MEKi trial

Background

Preclinical studies of avelumab (anti–PD-L1) + binimetinib (MEK inhibitor [MEKi]) showed encouraging antitumor activity. We report results from the phase 1b JAVELIN PARP MEKi trial (NCT03637491) evaluating avelumab + binimetinib in patients with mPDAC.

Methods

Eligible patients had mPDAC and disease progression during or following 1–2 prior lines for advanced or metastatic disease. Patients received avelumab 800 mg intravenously every 2 weeks and binimetinib 30 or 45 mg orally twice daily. The primary endpoint for phase 1b was dose-limiting toxicity (DLT). Secondary endpoints included safety, confirmed objective response per investigator (RECIST 1.1), pharmacokinetics, immunogenicity, and biomarker analyses. PD-L1 expression (SP263 assay) and CD8+ tumor-infiltrating lymphocytes (TILs) in baseline tumor samples were assessed using immunohistochemistry. Molecular alterations were assessed via plasma ctDNA analyses. Blood samples were collected to assess trough concentrations for avelumab, binimetinib, and AR00426032 (binimetinib metabolite) and end-of-infusion concentration for avelumab.

Results

22 patients received avelumab + binimetinib 30 mg (n=10) or 45 mg (n=12); all discontinued treatment. Among 21 DLT-evaluable patients, DLTs occurred in 3/10 (30.0%) in the 30-mg group (mucosal inflammation, dermatitis acneiform, blood creatine phosphokinase increased [n=1 each]) and 5/11 (45.5%) in the 45-mg group (detachment of retinal pigment epithelium, abdominal pain, diarrhea, nausea, vomiting, rash pustular, hypertension, blood creatine phosphokinase increased [n=1 each]). Any-grade treatment-related adverse events (TRAEs) occurred in all 22 patients; grade =3 TRAEs occurred in 8 (80.0%) and 4 (33.3%) in the 30- and 45-mg groups, respectively, most commonly blood creatine phosphokinase increased (n=3 [30.0%], n=2 [16.7%], respectively). No treatment-related deaths occurred. Objective response rates (95% CI) in the 30- and 45-mg groups were 0% (0.0–30.8) and 8.3% (0.2–38.5; 1 partial response), respectively; 1 (10.0%) and 6 (50.0%) had a best overall response of stable disease. Tumor shrinkage was associated with higher baseline PD-L1 expression, higher number of CD8+ TILs, and MEK1/2, PIK3CA, and RNF43 alterations, whereas ERBB4 alterations correlated inversely with tumor size change. Available data indicate that avelumab, binimetinib, and AR00426032 exposures were within range of previous monotherapy studies.

Conclusions

This study was terminated before a recommended phase 2 dose was established. In patients with mPDAC who received avelumab + binimetinib, DLTs occurred in both dose groups, although TRAEs were generally consistent with single agent safety profiles. The 45-mg binimetinib dose had a higher number of patients with stable disease and one confirmed partial response. Biomarker findings provide insights into potential mechanisms of treatment resistance and response.

Trial Registration

NCT03637491

Ethics Approval

The trial was approved by each site’s independent ethics committee.

Biomarker analysis from a phase I study using gedatolisib+palbociclib+hormone therapy in ER+/HER2- metastatic breast cancer (mBC)

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Background: Endocrine therapy with a CDK4/6 inhibitor (CDKi) is standard of care (SOC) for patients (pts) with estrogen-receptor-positive (ER+) metastatic breast cancer (mBC). Resistance to therapy may arise from mutations in ESR1, PIK3CA, and activation of receptor tyrosine kinase signaling pathways. In this study, gedatolisib (G), a PI3KCA/mTOR inhibitor, was added to a CDKi (palbociclib, P) + letrozole (L) or fulvestrant (F) for treatment of pts with ER+/HER2- mBC. Methods: This phase 1b study (NCT02684032) comprises a dose escalation phase evaluating the dose-limiting toxicity and maximum tolerated dose of G+P+L/F and a dose expansion phase assessing the objective response rate of G+P+L/F, compared with historical data for P+L or P+F. Response was assessed using RECIST v1.1. Genomic and transcriptomic analyses were performed on archival pt tumor biopsies. Longitudinal plasma ctDNA analysis was performed on samples taken at baseline, on-treatment, and end-of-treatment. Unsupervised data analysis was conducted. Results: Genomic information was available for 25 of 35 pts with measurable disease (G+P+L: 11; G+P+F: 14). No relationship was observed between responses (1 complete response [CR] and 11 partial responses [PR]) and baseline PIK3CA pathway alterations. Pt tumor tissue analysis (n = 25) confirmed pts with FGF3/4/19 amplification (n = 4) had larger changes in tumor size in response to G+P+L/F (p = 0.029). Of the 6 pts with an ESR1 mutation, 1 pt with an ESR1 Y537S mutation exhibited a partial response (PR) to G+P+L. Longitudinal plasma ctDNA analysis (73-gene panel) revealed that decreases in PIK3CA and PTEN were most associated with clinical response. Plasma sample analysis (n = 21) showed that pts with somatic alterations in EGFR (n = 4) had a greater response to therapy (p = 0.066), compared with pts without somatic EGFR alterations. Transcriptomic profiling also revealed responsive patients had higher levels of EGFR expression. Pts exhibiting CR/PR had a lower somatic tumor mutation burden at Cycle 5 Day 1 compared with baseline (p = 0.0013). Conclusions: The addition of G to SOC endocrine + CDKi therapy may help overcome resistance due to activation of FGFR or EGFR signaling pathways and the ESR1 Y537S mutation. Somatic frequency changes of PI3K pathway alterations were most correlated with clinical response. Genomic data analysis from dose expansion samples is currently ongoing. Clinical trial information: NCT02684032 .

Phase Ib Study of Utomilumab (PF-05082566), a 4-1BB/CD137 Agonist, in Combination with Pembrolizumab (MK-3475) in Patients with Advanced Solid Tumors

Purpose: This phase Ib study (NCT02179918) evaluated the safety, antitumor activity, pharmacokinetics, and pharmacodynamics of utomilumab, a fully human IgG2 mAb agonist of the T-cell costimulatory receptor 4-1BB/CD137 in combination with the humanized, PD-1-blocking IgG4 mAb pembrolizumab in patients with advanced solid tumors.Experimental Design: Utomilumab (0.45-5.0 mg/kg) and pembrolizumab (2 mg/kg) were administered intravenously every 3 weeks. Utomilumab dose escalation was conducted using the time-to-event continual reassessment method.Results: Twenty-three patients received combination treatment with no dose-limiting toxicities. Treatment-emergent adverse events were mostly grades 1 to 2, without any treatment-related discontinuations. Six patients (26.1%) had confirmed complete or partial responses. Pharmacokinetics and immunogenicity of utomilumab and pembrolizumab were similar when administered alone or in combination. A trend toward higher levels of activated memory/effector peripheral blood CD8⁺ T cells was observed in responders versus nonresponders.Conclusions: The safety, tolerability, and clinical activity demonstrated by utomilumab in combination with pembrolizumab support further investigation in patients with advanced solid tumors. Clin Cancer Res; 23(18); 5349-57. ©2017 AACRSee related commentary by Pérez-Ruiz et al., p. 5326.

Identification of a Novel Allosteric Inhibitory Site on Tryptophan Hydroxylase 1 Enabling Unprecedented Selectivity Over all Related Hydroxylases

Pulmonary arterial hypertension (PAH) has demonstrated multi-serotonin receptor dependent pathologies, characterized by increased tone (5-HT_1B receptor) and complex lesions (SERT, 5-HT_1B, 5-HT_2B receptors) of the pulmonary vasculature together with right ventricular hypertrophy, ischemia and fibrosis (5-HT_2B receptor). Selective inhibitors of individual signaling elements – SERT, 5-HT_2A, 5HT_2B, and combined 5-HT2_A/B receptors, have all been tested clinically and failed. Thus, inhibition of tryptophan hydroxylase 1 (TPH1), the rate limiting step in 5-HT synthesis, has been suggested as a more broad, and thereby more effective, mode of 5-HT inhibition. However, selectivity over non-pathogenic enzyme family members, TPH2, phenylalanine hydroxylase, and tyrosine hydroxylase has hampered therapeutic development. Here we describe the site/sequence, biochemical, and biophysical characterization of a novel allosteric site on TPH1 through which selectivity over TPH2 and related aromatic amino acid hydroxylases is achieved. We demonstrate the mechanism of action by which novel compounds selectively inhibit TPH1 using surface plasma resonance and enzyme competition assays with both tryptophan ligand and BH4 co-factor. We demonstrate 15-fold greater potency within a human carcinoid cell line versus the most potent known TPH1/2 non-specific inhibitor. Lastly, we detail a novel canine in vivo system utilized to determine effective biologic inhibition of newly synthesized 5-HT. These findings are the first to demonstrate TPH1-selective inhibition and may pave the way to a truly effective means to reduce pathologic 5-HT and thereby treat complex remodeling diseases such as PAH.

Peginterferon Beta-1a Shows Antitumor Activity as a Single Agent and Enhances Efficacy of Standard of Care Cancer Therapeutics in Human Melanoma, Breast, Renal, and Colon Xenograft Models

Because of its tumor-suppressive effect, interferon-based therapy has been used for the treatment of melanoma. However, limited data are available regarding the antitumor effects of pegylated interferons, either alone or in combination with approved anticancer drugs. We report that treatment of human WM-266-4 melanoma cells with peginterferon beta-1a induced apoptotic markers. Additionally, peginterferon beta-1a significantly inhibited the growth of human SK-MEL-1, A-375, and WM-266-4 melanoma xenografts established in immunocompromised mice. Peginterferon beta-1a regressed large, established WM-266-4 xenografts in nude mice. Treatment of SK-MEL-1 tumor-bearing mice with a combination of peginterferon beta-1a and the MEK inhibitor PD325901 ((R)-N-(2,3-dihydroxypropoxy)-3,4-difluoro-2-(2-fluoro-4-iodophenylamino)benzamide) significantly improved tumor growth inhibition compared with either agent alone. Examination of the antitumor activity of peginterferon beta-1a in combination with approved anticancer drugs in breast and renal carcinomas revealed improved antitumor activity in these preclinical xenograft models, as did the combination of peginterferon beta-1a and bevacizumab in a colon carcinoma xenograft model.

The effect of 2 mMol glutamine supplementation on HSP70 and TNF-α release by LPS stimulated blood from healthy children

OBJECTIVE

Glutamine has been shown to promote heat shock protein 70 (HSP70) release both within experimental in vitro models of sepsis (2-10 mM) and in adults post trauma (0.5 g/kg), although the efficacy varies and is dependent on the model used. The effect of glutamine supplementation on HSP70 release in children is less clear. Therefore, the aim of this study was to investigate the effect of 2 mM glutamine added to incubation media on HSP70 and inflammatory mediator release in an in vitro model of paediatric sepsis using whole blood from healthy paediatric volunteers.

METHODS

An in vitro whole blood endotoxin stimulation model using 1 μg/ml lipopolysaccharide (LPS) over a 24 h time period was used to investigate the effects of 2 mM glutamine on HSP70 and inflammatory mediator release in healthy children.

RESULTS

The addition of 2 mM glutamine to the incubation media significantly increased HSP70 release over time (p < 0.05). This was associated with an early pro-inflammatory effect on TNF-α release at 4 h (p < 0.005) which was not seen at 24 h. There was a non significant trend towards higher levels of IL-6 and IL-10 following the addition of 2 mM glutamine, which appears to differ from the response reported in adult and animal models.

CONCLUSION

Glutamine supplementation of incubation media promotes HSP70 and early TNF- α release in an in vitro model using blood samples from healthy children.

Abstract 1734: In vitro characterization of EGF816, a third-generation mutant-selective EGFR inhibitor

EGFR is a major oncogene in NSCLC. Patients with the oncogenic mutations L858R and Ex19Del are responsive to the first generation pan-EGFR tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. The associated dose-limiting toxicities (DLTs) are severe rash and GI tolerability due to WT EGFR inhibition. However, therapy is universally limited by the development of acquired drug resistance where EGFR gatekeeper mutation T790M accounts for 50% of incidence. Second generation irreversible pan-EGFR TKI afatinib was developed to overcome T790M resistance. Though effective in animal models, the efficacy of afatinib on T790M patients is largely limited by its DLTs due to potent inhibition of WT EGFR. A strong medical need still exists for better tolerated therapy to treat NSCLC patients harboring EGFR mutations. Here we report the discovery and development of a potent third generation, irreversible mutant-selective EGFR TKI that is expected to improve/maintain efficacy on oncogenic EGFR mutant patients while demonstrating reduced side effects. EGF816 potently inhibits both activating (L858R and Ex19Del) and T790M resistant mutations in various cellular assays; it is selective against a large panel of kinases in both Ambit and BaF3 profiling, and more importantly is selective against WT EGFR. EGF816 is efficacious in mutant EGFR-driven xenograft models, is well tolerated in IND-enabling toxicology studies, and is entering phase 1 trials.

Citation Format: Yong Jia, Jose Juarez, Mari Manuia, Gerald Lelais, Shailaja Kasibhatla, Oliver Long, Matthew McNeill, Michael DiDonato, Badry Bursulaya, Debbie Liao, Eric Murphy, Robert Epple, Thomas Marsilje, Nuzhat Pathan, Pierre-Yves Michellys, Steven Bender, Jennifer Harris. In vitro characterization of EGF816, a third-generation mutant-selective EGFR inhibitor. [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 1734. doi:10.1158/1538-7445.AM2014-1734

Structure-based design of 2,6,7-trisubstituted-7H-pyrrolo[2,3-d]pyrimidines as Aurora kinases inhibitors

This Letter reports the optimization of a pyrrolopyrimidine series as dual inhibitors of Aurora A/B kinases. This series derived from a pyrazolopyrimidine series previously reported as inhibitors of aurora kinases and CDKs. In an effort to improve the selectivity of this chemotype, we switched to the pyrrolopyrimidine core which allowed functionalization on C-2. In addition, the modeling rationale was based on superimposing the structures of Aurora-A kinase and CDK2 which revealed enough differences leading to a path for selectivity improvement. The synthesis of the new series of pyrrolopyrimidine analogs relied on the development of a different route for the two key intermediates 7 and 19 which led to analogs with both tunable activity against CDK1 and maintained cell potency.

Synthesis, SAR and biological evaluation of 1,6-disubstituted-1H-pyrazolo[3,4-d]pyrimidines as dual inhibitors of Aurora kinases and CDK1

Since the early 2000s, the Aurora kinases have become major targets of oncology drug discovery particularly Aurora-A and Aurora-B kinases (AKA/AKB) for which the selective inhibition in cells lead to different phenotypes. In addition to targeting these Aurora kinases involved in mitosis, CDK1 has been added as a primary inhibition target in hopes of enhancing the cytotoxicity of our chemotypes harboring the pyrazolopyrimidine core. SAR optimization of this series using the AKA, AKB and CDK1 biochemical assays led to the discovery of the compound 7h which combines strong potency against the 3 kinases with an acceptable microsomal stability. Finally, switching from a primary amide to a two-substituted pyrrolidine amide gave rise to compound 15a which exhibited the desired AKA/CDK1 inhibition phenotype in cells but showed moderate activity in animal models using HCT116 tumor cell lines.

Ahp2 (Hop2) function in Arabidopsis thaliana (Ler) is required for stabilization of close alignment and synaptonemal complex formation except for the two short arms that contain nucleolus organizer regions

A cytological comparative analysis of male meiocytes was performed for Arabidopsis wild type and the ahp2 (hop2) mutant with emphasis on ahp2's largely uncharacterized prophase I. Leptotene progression appeared normal in ahp2 meiocytes; chromosomes exhibited regular axis formation and assumed a typical polarized nuclear organization. In contrast, 4',6'-diamidino-2-phenylindole-stained ahp2 pachytene chromosome spreads demonstrated a severe reduction in stabilized pairing. However, transmission electron microscopy (TEM) analysis of sections from meiocytes revealed that ahp2 chromosome axes underwent significant amounts of close alignment (44% of total axis). This apparent paradox strongly suggests that the Ahp2 protein is involved in the stabilization of homologous chromosome close alignment. Fluorescent in situ hybridization in combination with Zyp1 immunostaining revealed that ahp2 mutants undergo homologous synapsis of the nucleolus-organizer-region-bearing short arms of chromosomes 2 and 4, despite the otherwise "nucleus-wide" lack of stabilized pairing. The duration of ahp2 zygotene was significantly prolonged and is most likely due to difficulties in chromosome alignment stabilization and subsequent synaptonemal complex formation. Ahp2 and Mnd1 proteins have previously been shown, "in vitro," to form a heterodimer. Here we show, "in situ," that the Ahp2 and Mnd1 proteins are synchronous in their appearance and disappearance from meiotic chromosomes. Both the Ahp2 and Mnd1 proteins localize along the chromosomal axis. However, localization of the Ahp2 protein was entirely foci-based whereas Mnd1 protein exhibited an immunostaining pattern with some foci along the axis and a diffuse staining for the rest of the chromosome.

Lumiliximab (anti-CD23 antibody) mediates apoptosis and antitumor activity in chronic lymphocytic leukemia (CLL) cells and CD23+ lymphoma cell lines

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Background: Given the success of treating CLL with antibody therapies, interest in those directed at alternative B-cell antigens remains high. Lumiliximab is a chimeric macaque and human anti-CD23 monoclonal antibody whose antigen is expressed on almost all CLL cells. Methods: We examined lumiliximab’s ability to mediate direct apoptosis, antibody-dependent cellular cytotoxicity (ADCC), and complement-dependent cytotoxicity (CDC) against primary CLL cells and CD23+ B-cell lines. Apoptosis was measured with a flow-cytometry based assay for active caspase-3. ADCC was determined by 51Cr-release assay. CDC assays were performed in the presence of 30% autologous plasma from patients and quantified by propidium iodide staining. Western blotting analysis was used to monitor protein expression before and after treatment with lumiliximab. The CD23+ human lymphoma SKW6.4 cell line was used for in vivo evaluation of lumiliximab in a disseminated human lymphoma model. Results: Lumiliximab mediates apoptosis, ADCC, and CDC in CD23+ B-cell lines. However, in primary CLL cells, the primary mechanism of cell killing appears to be mediated via apoptosis. Apoptosis induced by lumiliximab occurs mainly through the intrinsic pathway used by other CLL therapies. Lumiliximab decreased expression of Bcl-2 and XIAP and inhibited Akt activation in CLL cells. Lumiliximab when combined in vitro or in vivo with rituximab or fludarabine effectively mediates synergistic cytotoxicity against primary CLL cells and CD23+ B-cell lines. Significant antitumor activity was also observed with lumiliximab vs a control antibody in a SCID mouse model of human B-cell lymphoma (P <.01). More importantly, lumiliximab + rituximab or lumiliximab + fludarabine results in prolonged survival vs lumiliximab, rituximab, or fludarabine single-agent treatment. Conclusions: These results indicate that lumiliximab induces apoptosis by activating caspases and downregulating antiapoptotic proteins, and suggest that in combination with rituximab or chemotherapy, lumiliximab synergistically enhances antitumor activity in CLL or other B-cell malignancies in which this antigen is overexpressed.

No significant financial relationships to disclose.

Pathophysiology of meningococcal meningitis and septicaemia

Neisseria meningitidis is remarkable for the diversity of interactions that the bacterium has with the human host, ranging from asymptomatic nasopharyngeal colonisation affecting virtually all members of the population; through focal infections of the meninges, joints, or eye; to the devastating and often fatal syndrome of meningococcal septic shock and purpura fulminans.

Microtubule-targeting drugs induce bcl-2 phosphorylation and association with Pin1

Bcl-2 is a critical suppressor of apoptosis that is overproduced in many types of cancer. Phosphorylation of the Bcl-2 protein is induced on serine residues in tumor cells arrested by microtubule-targeting drugs (paclitaxel, vincristine, nocodazole) and has been associated with inactivation of antiapoptotic function through an unknown mechanism. Comparison of a variety of pharmacological inhibitors of serine/threonine-specific protein kinases demonstrated that the cyclin-dependent kinase inhibitor, flavopiridol, selectively blocks Bcl-2 phosphorylation induced by antimicrotubule drugs. Bcl-2 could also be coimmunoprecipitated with the kinase Cdc2 in M-phase-arrested cells, suggesting that Cdc2 may be responsible for phosphorylation of Bcl-2 in cells treated with microtubule-targeting drugs. Examination of several serine-->alanine substitution mutants of Bcl-2 suggested that serine 70 and serine 87 represent major sites of Bcl-2 phosphorylation induced in response to microtubule-targeting drugs. Both these serines are within sequence contexts suitable for proline-directed kinases such as Cdc2. Phosphorylated Bcl-2 protein was discovered to associate in M-phase-arrested cells with Pin1, a mitotic peptidyl prolyl isomerase (PPIase) known to interact with substrates of Cdc2 during mitosis. In contrast, phosphorylation of Bcl-2 induced by microtubule-targeting drugs did not alter its ability to associate with Bcl-2 (homodimerization), Bax, BAG1, or other Bcl-2-binding proteins. Since the region in Bcl-2 containing serine 70 and serine 87 represents a proline-rich loop that has been associated with autorepression of its antiapoptotic activity, the discovery of Pin1 interactions with phosphorylated Bcl-2 raises the possibility that Pin1 alters the conformation of Bcl-2 and thereby modulates its function in cells arrested with antimicrotubule drugs.

TUCAN, an antiapoptotic caspase-associated recruitment domain family protein overexpressed in cancer

Caspase-associated recruitment domains (CARDs) are protein interaction domains that participate in activation or suppression of CARD-carrying members of the caspase family of apoptosis-inducing proteases. A novel CARD-containing protein was identified that is overexpressed in some types of cancer and that binds and suppresses activation of procaspase-9, which we term TUCAN (tumor-up-regulated CARD-containing antagonist of caspase nine). The CARD domain of TUCAN selectively binds itself and procaspase-9. TUCAN interferes with binding of Apaf1 to procaspase-9 and suppresses caspase activation induced by the Apaf1 activator, cytochrome c. Overexpression of TUCAN in cells by stable or transient transfection inhibits apoptosis and caspase activation induced by Apaf1/caspase-9-dependent stimuli, including Bax, VP16, and staurosporine, but not by Apaf1/caspase-9-independent stimuli, Fas and granzyme B. High levels of endogenous TUCAN protein were detected in several tumor cell lines and in colon cancer specimens, correlating with shorter patient survival. Thus, TUCAN represents a new member of the CARD family that selectively suppresses apoptosis induced via the mitochondrial pathway for caspase activation.

Microtubule-targeting drugs induce Bcl-2 phosphorylation and association with Pin1

Bcl-2 is a critical suppressor of apoptosis that is overproduced in many types of cancer. Phosphorylation of the Bcl-2 protein is induced on serine residues in tumor cells arrested by microtubule-targeting drugs (paclitaxel, vincristine, nocodazole) and has been associated with inactivation of antiapoptotic function through an unknown mechanism. Comparison of a variety of pharmacological inhibitors of serine/threonine-specific protein kinases demonstrated that the cyclin-dependent kinase inhibitor, flavopiridol, selectively blocks Bcl-2 phosphorylation induced by antimicrotubule drugs. Bcl-2 could also be coimmunoprecipitated with the kinase Cdc2 in M-phase-arrested cells, suggesting that a Cdc2 may be responsible for phosphorylation of Bcl-2 in cells treated with microtubule-targeting drugs. Examination of several serine-->alanine substitution mutants of Bcl-2 suggested that serine 70 and serine 87 represent major sites of Bcl-2 phosphorylation induced in response to microtubule-targeting drugs. Both these serines are within sequence contexts suitable for proline-directed kinases such as Cdc2. Phosphorylated Bcl-2 protein was discovered to associate in M-phase-arrested cells with Pin1, a mitotic peptidyl prolyl isomerase (PPIase) known to interact with substrates of Cdc2 during mitosis. In contrast, phosphorylation of Bcl-2 induced by microtubule-targeting drugs did not alter its ability to associate with Bcl-2 (homodimerization), Bax, BAG1, or other Bcl-2-binding proteins. Since the region in Bcl-2 containing serine 70 and serine 87 represents a proline-rich loop that has been associated with autorepression of its antiapoptotic activity, the discovery of Pin1 interactions with phosphorylated Bcl-2 raises the possibility that Pin1 alters the conformation of Bcl-2 and thereby modulates its function in cells arrested with antimicrotubule drugs.

A myocardial cytotoxic process is involved in the cardiac dysfunction of meningococcal septic shock

OBJECTIVE

Myocardial dysfunction is a characteristic component of meningococcal septic shock and contributes to the persisting high mortality from the disease. Specific treatment of the myocardial failure has been hampered by the lack of understanding of its pathophysiology. We were interested to determine whether myocardial cell death was occurring in the presence of meningococcal septicemia and whether it correlated with the degree of left ventricular dysfunction and disease severity. We therefore investigated the release of cardiac troponin I (cTnI), a sensitive and specific marker of myocardial cell death, and related this to the severity of disease and cardiac dysfunction.

DESIGN

Prospective study

SETTING

Pediatric intensive care unit

SUBJECTS

Patients admitted to the pediatric intensive care unit with a diagnosis of meningococcal septicemia.

INTERVENTIONS

Serum concentrations of cTnI were determined at admission to intensive care in 101 children with meningococcal septicemia and serially in 37 children. Changes in cTnI were related to disease severity as measured by the Pediatric Risk of Mortality score and two markers of cardiac dysfunction.

MEASUREMENTS AND MAIN RESULTS

Serum concentrations of cTnI were elevated above the range for healthy children in 24% of children with meningococcal septicemia at admission and in 62% of patients within 48 hrs. The peak concentrations occurred between 12 and 36 hrs after admission. There were significant correlations between cTnI levels and disease severity and between cTnI levels and the degree of myocardial depression measured by quantitative transthoracic echocardiography and peak inotrope requirements.

CONCLUSIONS

The elevated serum concentrations of cTnI indicate that myocardial cell death is occurring in meningococcal septicemia. The relationship between cTnI and markers of myocardial function suggest that the cell death may have a role in the pathogenesis of myocardial dysfunction in meningococcal septicemia. Elucidation of the mechanism responsible for myocardial injury may lead to the development of therapeutic interventions to prevent or limit this cardiac damage.

The tumor suppressor PTEN regulates T cell survival and antigen receptor signaling by acting as a phosphatidylinositol 3-phosphatase

The tumor suppressor gene PTEN encodes a 55-kDa enzyme that hydrolyzes both protein phosphotyrosyl and 3-phosphorylated inositol phospholipids in vitro. We have found that the latter activity is physiologically relevant in intact T cells. Expression of active PTEN lead to a 50% loss of transfected cells due to increased apoptosis, which was completely prevented by coexpression of a constitutively active, membrane-bound form of protein kinase B. A mutant of PTEN selectively lacking lipid phosphatase activity, but retaining protein phosphatase activity, had no effects on cell number. Active (but not mutant) PTEN also decreased TCR-induced activation of the mitogen-activated protein kinase ERK2 (extracellular signal-related kinase 2), as seen after inhibition of phosphatidylinositol 3-kinase. Our data indicate that PTEN is a phosphatidylinositol 3-phosphatase in T cells, and we suggest that PTEN may play a role in the regulation of T cell survival and TCR signaling by directly opposing phosphatidylinositol 3-kinase.

Ca2+-induced apoptosis through calcineurin dephosphorylation of BAD

The Ca2+-activated protein phosphatase calcineurin induces apoptosis, but the mechanism is unknown. Calcineurin was found to dephosphorylate BAD, a pro-apoptotic member of the Bcl-2 family, thus enhancing BAD heterodimerization with Bcl-xL and promoting apoptosis. The Ca2+-induced dephosphorylation of BAD correlated with its dissociation from 14-3-3 in the cytosol and translocation to mitochondria where Bcl-xL resides. In hippocampal neurons, L-glutamate, an inducer of Ca2+ influx and calcineurin activation, triggered mitochondrial targeting of BAD and apoptosis, which were both suppressible by coexpression of a dominant-inhibitory mutant of calcineurin or pharmacological inhibitors of this phosphatase. Thus, a Ca2+-inducible mechanism for apoptosis induction operates by regulating BAD phosphorylation and localization in cells.