Safety and efficacy of peptide receptor radionuclide therapy in neuroendocrine tumors: A single center experience

Peptide receptor radionucleotide therapy (PRRT) with 177Lu-dotatate is widely used for the treatment of patients with neuroendocrine tumors (NETs). We analyzed data from 104 patients with NETs treated with 177Lu -dotatate at a US academic center between December 2017 and October 2020 to better understand patterns of long-term efficacy, safety, and toxicity in the real-world setting. 177Lu-dotatate (200 mCi) was administered every eight weeks for four doses. The most common sites of primary disease were small intestine NETs (n = 49, 47%), pancreatic NETs (n = 32, 31%), and lung NETs (n = 7, 7%). Twenty-seven percent had Ki-67 <3%, 49% had Ki-67 between 3-20%, and 13.5% had Ki-67 >20%. The cohort had been pretreated with a median of two prior lines of treatment. Forty percent had received prior liver-directed treatment. Seventy-four percent of patients completed all four doses of treatment. The objective response rate was 18%. The median time-to-treatment failure/death was significantly longer for small-bowel NETs when compared to pancreatic NETs (37.3 months vs. 13.2 months, p = 0.001). In a multivariate model, Ki-67, primary site, and liver tumor burden ≥50% were found to independently predict time-to-treatment failure/death. Around 40% of patients experienced adverse events of ≥grade 3 severity. Treatment-related adverse events leading to discontinuation of therapy happened in 10% of patients. Preexisting mesenteric/peritoneal disease was present in 33 patients; seven of these patients developed bowel-related toxicities including two grade 5 events. We also report two cases of delayed-onset minimal change nephrotic syndrome, which occurred 14 and 27 months after the last dose of PRRT. Lastly, we describe six patients who developed rapid tumor progression in the liver leading to terminal liver failure within 7.3 months from the start of PRRT, and identify potential risk factors associated with this occurrence, which will need further study.

Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype

Papillary thyroid cancer (PTC) is the most common endocrine malignancy. 10% to 15% of individuals show familial clustering with three or more affected members, but the factors underlying this risk are unknown. In a group of recently studied individuals with POT1 pathogenic variants and ultra-long telomere length, PTC was the second most common solid tumor. We tested whether variants in POT1 and four other telomere-maintenance genes associated with familial cancer underlie PTC susceptibility. Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD. They were found in 4.5% and 1.5% of familial and unselected cases, respectively. Individuals harboring these variants had ultra-long telomere length, and 15 of 18 (83%) developed other cancers, of which melanoma, lymphoma, and sarcoma were most common. Among individuals with PTC and melanoma, 22% carried a deleterious germline variant, suggesting that a long telomere syndrome might be clinically recognizable. Successive generations had longer telomere length than their parents and, at times, developed more cancers at younger ages. Tumor sequencing identified a single oncogenic driver, BRAF p.Val600Glu, in 10 of 10 tumors studied, but no telomere-maintenance mechanism, including at the TERT promoter. These data identify a syndromic subset of PTCs with locus heterogeneity and telomere lengthening as a convergent mechanism. They suggest these germline variants lower the threshold to cancer by obviating the need for an acquired telomere-maintenance mechanism in addition to sustaining the longevity of oncogenic mutations.

A phase II study of bevacizumab and temsirolimus in advanced extra-pancreatic neuroendocrine tumors

We assessed the efficacy and safety of combining bevacizumab with temsirolimus in patients with advanced extra-pancreatic neuroendocrine tumors. This NCI-sponsored multicenter, open-label, phase II study (NCT01010126) enrolled patients with advanced, recurrent, or metastatic extra-pancreatic neuroendocrine tumors. All patients were treated with temsirolimus and bevacizumab until disease progression or unacceptable toxicity. Temsirolimus 25 mg was administered i.v. on days 1, 8, 15, and 22 and bevacizumab 10 mg/kg i.v. on days 1 and 15 of a 4-week cycle. Discontinuation of temsirolimus or bevacizumab did not require discontinuation of the other agent. The primary endpoints were objective response rate and 6-month progression-free survival rate. Fifty-nine patients were enrolled in this study, and 54 were evaluated for efficacy and adverse events. While median progression-free survival was 7.1 months, the median duration of treatment with temsirolimus was 3.9 months and that with bevacizumab was 3.5 months. The objective response rate of combination therapy was 2%, and 6-month progression-free survival was 48%. The most frequently reported grade 3-4 adverse events included fatigue (13%), hypertension (13%), and bleeding (13%). Close to 54% of the patients discontinued treatment due to adverse events, refusal of further treatment, or treatment delays. Three deaths occurred in the study, of which two were due to treatment-related bowel perforations. Given the minimal efficacy and increased toxicity seen with the combination of bevacizumab and temsirolimus, we do not recommend the use of this regimen in patients with advanced extra-pancreatic neuroendocrine tumors.

Randomized Study of Temozolomide or Temozolomide and Capecitabine in Patients With Advanced Pancreatic Neuroendocrine Tumors (ECOG-ACRIN E2211)

PURPOSE

Patients with advanced pancreatic neuroendocrine tumors (NETs) have few treatment options that yield objective responses. Retrospective and small prospective studies suggest that capecitabine and temozolomide are associated with high response rates (RRs) and long progression-free survival (PFS).

PATIENTS AND METHODS

E2211 was a multicenter, randomized, phase II trial comparing temozolomide versus capecitabine/temozolomide in patients with advanced low-grade or intermediate-grade pancreatic NETs. Key eligibility criteria included progression within the preceding 12 months and no prior temozolomide, dimethyl-triazeno-imidazole-carboxamide or dacarbazine, capecitabine or fluorouracil. The primary end point was PFS; secondary endpoints were overall survival, RR, safety, and methylguanine methyltransferase (MGMT) by immunohistochemistry and promoter methylation.

RESULTS

A total of 144 patients were enrolled between April 2013 and March 2016 to temozolomide (n = 72) or capecitabine and temozolomide (n = 72); the primary analysis population included 133 eligible patients. At the scheduled interim analysis in January 2018, the median PFS was 14.4 months for temozolomide versus 22.7 months for capecitabine/temozolomide (hazard ratio = 0.58), which was sufficient to reject the null hypothesis for the primary end point (stratified log-rank P = .022). In the final analysis (May 2021), the median overall survival was 53.8 months for temozolomide and 58.7 months for capecitabine/temozolomide (hazard ratio = 0.82, P = .42). MGMT deficiency was associated with response.

CONCLUSION

The combination of capecitabine/temozolomide was associated with a significant improvement in PFS compared with temozolomide alone in patients with advanced pancreatic NETs. The median PFS and RR observed with capecitabine/temozolomide are the highest reported in a randomized study for pancreatic NETs. MGMT deficiency was associated with response, and although routine MGMT testing is not recommended, it can be considered for select patients in need of objective response (ClinicalTrials.gov identifier: NCT01824875).

A Phase II Clinical Trial of Nivolumab and Temozolomide for Neuroendocrine Neoplasms

PURPOSE

Treatment options are limited in patients with metastatic neuroendocrine neoplasms (NEN). We present the results for a phase II trial of combination nivolumab and temozolomide in patients with advanced NEN along with results of immune changes in peripheral blood.

PATIENTS AND METHODS

NCT03728361 is a nonrandomized, phase II study of nivolumab and temozolomide in patients with NEN. The primary endpoint was response rate using RECIST 1.1. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. Immune profiling was performed by mass cytometry to evaluate the effect on peripheral blood immune cell subsets.

RESULTS

Among all 28 patients with NEN, the confirmed response rate was 9/28 [32.1%, 95% confidence interval (CI): 15.9-52.4]. Of 11 patients with lung NEN, the response rate was 64% (n = 7); there was a significant difference in responses by primary tumor location (lung vs. others, P = 0.020). The median PFS was 8.8 months (95% CI: 3.9-11.1 months), and median OS was 32.3 months (95% CI: 20.7-not reached months). Exploratory blood immune cell profiling revealed an increase in circulating CD8+ T cells (27.9% ± 13.4% vs. 31.7% ± 14.6%, P = 0.03) and a decrease in CD4+ T cells (59.6% ± 13.1% vs. 56.5% ± 13.0%, P = 0.001) after 2 weeks of treatment. LAG-3-expressing total T cells were lower in patients experiencing a partial response (0.18% ± 0.24% vs. 0.83% ± 0.55%, P = 0.028). Myeloid-derived suppressor cell levels increased during the study and did not correlate with response.

CONCLUSIONS

Combination nivolumab and temozolomide demonstrated promising activity in NEN. See related commentary by Velez and Garon, p. 691.

From bench to clinic: Emerging therapies for corneal scarring

Corneal diseases are one of the leading causes of moderate-to-severe visual impairment and blindness worldwide, after glaucoma, cataract, and retinal disease in overall importance. Given its tendency to affect people at a younger age than other blinding conditions such as cataract and glaucoma, corneal scarring poses a huge burden both on the individuals and society. Furthermore, corneal scarring and fibrosis disproportionately affects people in poorer and remote areas, making it a significant ophthalmic public health problem. Traditional medical strategies, such as topical corticosteroids, are not effective in preventing fibrosis or scars. Corneal transplantation, the only effective sight-restoring treatment for corneal scars, is curbed by challenges including a severe shortage of tissue, graft rejection, secondary conditions, cultural barriers, the lack of well-trained surgeons, operating rooms, and well-equipped infrastructures. Thanks to tremendous research efforts, emerging therapeutic options including gene therapy, protein therapy, cell therapy and novel molecules are in development to prevent the progression of corneal scarring and compliment the surgical options currently available for treating established corneal scars in clinics. In this article, we summarise the most relevant preclinical and clinical studies on emerging therapies for corneal scarring in recent years, showing how these approaches may prevent scarring in its early development.

Radiotherapy and paclitaxel plus pazopanib or placebo in anaplastic thyroid cancer (NRG/RTOG 0912): a randomised, double-blind, placebo-controlled, multicentre, phase 2 trial

BACKGROUND

Anaplastic thyroid cancer is a rare and aggressive cancer with no standard radiotherapy-based local treatment. Based on data suggesting synergy between pazopanib and paclitaxel in anaplastic thyroid cancer, NRG Oncology did a double-blind, placebo-controlled, randomised phase 2 clinical trial comparing concurrent paclitaxel and intensity-modulated radiotherapy (IMRT) with the addition of pazopanib or placebo with the aim of improving overall survival in this patient population.

METHODS

Eligible patients were aged 18 years or older with a pathological diagnosis of anaplastic thyroid cancer, any TNM stage, Zubrod performance status of 0-2, no recent haemoptysis or bleeding, and no brain metastases. Patients were enrolled from 34 centres in the USA. Initially, a run-in was done to establish safety. In the randomised phase 2 trial, patients in the experimental group (pazopanib) received 2-3 weeks of weekly paclitaxel (80 mg/m2) intravenously and daily pazopanib suspension 400 mg orally followed by concurrent weekly paclitaxel (50 mg/m2), daily pazopanib (300 mg), and IMRT 66 Gy given in 33 daily fractions (2 Gy fractions). In the control group (placebo), pazopanib was replaced by matching placebo. Patients were randomly assigned (1:1) to the two treatment groups by permuted block randomisation by NRG Oncology with stratification by metastatic disease. All investigators, patients, and funders of the study were masked to group allocation. The primary endpoint was overall survival in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. This trial is registered with Clinicaltrials.gov, NCT01236547, and is complete.

FINDINGS

The safety run-showed the final dosing regimen to be safe based on two out of nine participants having adverse events of predefined concern. Between June 23, 2014, and Dec 30, 2016, 89 patients were enrolled to the phase 2 trial, of whom 71 were eligible (36 in the pazopanib group and 35 in the placebo group; 34 [48%] males and 37 [52%] females). At the final analysis (data cutoff March 9, 2020), with a median follow-up of 2·9 years (IQR 0·002-4·0), 61 patients had died. Overall survival was not significantly improved with pazopanib versus placebo, with a median overall survival of 5·7 months (95% CI 4·0-12·8) in the pazopanib group versus 7·3 months (4·3-10·6) in the placebo group (hazard ratio 0·86, 95% CI 0·52-1·43; one-sided log-rank p=0·28). 1-year overall survival was 37·1% (95% CI 21·1-53·2) in the pazopanib group and 29·0% (13·2-44·8) in the placebo group. The incidence of grade 3-5 adverse events did not differ significantly between the treatment groups (pazopanib 88·9% [32 of 36 patients] and placebo 85·3% [29 of 34 patients]; p=0·73). The most common clinically significant grade 3-4 adverse events in the 70 eligible treated patients (36 in the pazopanib group and 34 in the placebo group) were dysphagia (13 [36%] vs 10 [29%]), radiation dermatitis (8 [22%] vs 13 [38%]), increased alanine aminotransferase (12 [33%] vs none), increased aspartate aminotransferase (eight [22%] vs none), and oral mucositis (five [14%] vs eight [24%]). Treatment-related serious adverse events were reported for 16 (44%) patients on pazopanib and 12 (35%) patients on placebo. The most common serious adverse events were dehydration and thromboembolic event (three [8%] each) in patients on pazopanib and oral mucositis (three [8%]) in those on placebo. There was one treatment-related death in each group (sepsis in the pazopanib group and pneumonitis in the placebo group).

INTERPRETATION

To our knowledge, this study is the largest randomised anaplastic thyroid cancer study that has completed accrual showing feasibility in a multicenter NCI National Clinical Trials Network setting. Although no significant improvement in overall survival was recorded in the pazopanib group, the treatment combination was shown to be feasible and safe, and hypothesis-generating data that might warrant further investigation were generated.

FUNDING

National Cancer Institute and Novartis.

TAK1 blockade as a therapy for retinal neovascularization

Retinal neovascularization, or pathological angiogenesis in the retina, is a leading cause of blindness in developed countries. Transforming growth factor-β-activated kinase 1 (TAK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) activated by TGF-β1 and other proinflammatory cytokines. TAK1 is also a key mediator of proinflammatory signals and plays an important role in maintaining vascular integrity upon proinflammatory cytokine stimulation such as TNFα. However, its role in pathological angiogenesis, particularly in retinal neovascularization, remains unclear. Here, we investigate the regulatory role of TAK1 in human endothelial cells responding to inflammatory stimuli and in a rat model of oxygen-induced retinopathy (OIR) featured retinal neovascularization. Using TAK1 knockout human endothelial cells that subjected to inflammatory stimuli, transcriptome analysis revealed that TAK1 is required for activation of NFκB signaling and mediates its downstream gene expression related to endothelial activation and angiogenesis. Moreover, pharmacological inhibition of TAK1 by 5Z-7-oxozeaenol attenuated angiogenic activities of endothelial cells. Transcriptome analysis also revealed enrichment of TAK1-mediated NFκB signaling pathway in the retina of OIR rats and retinal neovascular membrane from patients with proliferative diabetic retinopathy. Intravitreal injection of 5Z-7-oxozeaenol significantly reduced hypoxia-induced inflammation and microglial activation, thus attenuating aberrant retinal angiogenesis in OIR rats. Our data suggest that inhibition of TAK1 may have therapeutic potential for the treatment of retinal neovascular pathologies.

Kinase inhibitors in thyroid cancers

Objective

The treatment landscape for thyroid cancers has changed rapidly with the availability of kinase inhibitors against VEGFR, BRAF, MEK, NTRK, and RET. We provide an up-to-date review of the role of kinase inhibitors in thyroid cancer and discuss upcoming trials.

Design & Methods

A comprehensive review of the available literature describing kinase inhibitors in thyroid cancer was performed.

Results and Conclusions

Kinase inhibitors have become the standard of care for patients with metastatic radioactive iodine-refractory thyroid cancer. Short-term treatment can re-sensitize differentiated thyroid cancer to radioactive iodine, thereby potentially improving outcomes and sparing toxicities associated with the long-term use of kinase inhibitors. The approval of cabozantinib as salvage therapy for progressive radioactive iodine-refractory differentiated thyroid cancer following failure with sorafenib or lenvatinib adds to the available armamentarium of active agents. Vandetanib and cabozantinib have become mainstay treatments for metastatic medullary thyroid cancer regardless of RET mutation status. Selpercatinib and pralsetinib, potent and selective receptor kinase inhibitors with activity against RET, have revolutionized the treatment paradigm for medullary thyroid cancers and other cancers with driver mutations in RET. Dabrafenib plus trametinib for BRAF mutated anaplastic thyroid cancer provides an effective treatment option for this aggressive cancer with a dismal prognosis. In order to design the next generation of agents for thyroid cancer, future efforts will need to focus on developing a better understanding of the mechanisms of resistance to kinase inhibition including bypass signaling and escape mutations.

Dabrafenib Versus Dabrafenib + Trametinib in BRAF-Mutated Radioactive Iodine Refractory Differentiated Thyroid Cancer: Results of a Randomized, Phase 2, Open-Label Multicenter Trial

Background: Oncogenic BRAF mutations are commonly found in advanced differentiated thyroid cancer (DTC), and reports have shown efficacy of BRAF inhibitors in these tumors. We investigated the difference in response between dabrafenib monotherapy and dabrafenib + trametinib therapy in patients with BRAF-mutated radioactive iodine refractory DTC. Methods: In this open-label randomized phase 2 multicenter trial, patients aged ≥18 years with BRAF-mutated radioactive iodine refractory DTC with progressive disease by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 within 13 months before enrollment were eligible. Patients were randomly assigned to receive dabrafenib alone or dabrafenib + trametinib. The primary endpoint was objective response rate by modified RECIST (minor response of -20% to -29%, partial and complete response) within the first 24 weeks of therapy. Trial Registration Number: NCT01723202. Results: A total of 53 patients were enrolled. The objective response rate (modified RECIST) was 42% (11/26 [95% confidence interval {CI} 23-63%]) with dabrafenib versus 48% (13/27 [CI 29-68%]) with dabrafenib + trametinib (p = 0.67). Objective response rate (RECIST 1.1) was 35% (9/26 [CI 17-56%]) with dabrafenib and 30% (8/27 [CI 14-51%]) with dabrafenib + trametinib. Most common treatment-related adverse events included skin and subcutaneous tissue disorders (17/26, 65%), fever (13/26, 50%), hyperglycemia (12/26, 46%) with dabrafenib alone and fever (16/27, 59%), nausea, chills, fatigue (14/27, 52% each) with dabrafenib + trametinib. There were no treatment-related deaths. Conclusions: Combination dabrafenib + trametinib was not superior in efficacy compared to dabrafenib monotherapy in patients with BRAF-mutated radioiodine refractory progressive DTC.

Inhibitory Effects of 3',4'-Dihydroxyflavonol in a Mouse Model of Glaucoma Filtration Surgery and TGFβ1-Induced Responses in Human Tenon's Fibroblasts

Purpose

Cytotoxic agents such as mitomycin C (MMC) are part of the mainstay treatment for limiting subconjunctival scarring following glaucoma filtration surgery (GFS). However, a safer antifibrotic therapy is clinically needed. The anti-scarring properties of 3′,4′-dihydroxyflavonol (DiOHF) were evaluated in a mouse model of GFS and in cultured human Tenon's fibroblasts (HTFs).

Methods

GFS was performed in C57BL/6 mice receiving daily intraperitoneal injections of DiOHF or vehicle or a single intraoperative injection of MMC. Eyes were harvested on day 14 for assessment of collagen deposition, expression of alpha-smooth muscle actin (α-SMA), cluster of differentiation 31 (CD31), and 4-hydroxy-2-nonenal (4HNE) in the conjunctiva/Tenon's layer. The inhibitory effects of DiOHF on transforming growth factor β (TGFβ)-induced responses were also assessed in HTFs.

Results

Treatment with DiOHF demonstrated a reduction in collagen deposition at the GFS site compared to vehicle-treated mice. The degree of 4HNE-positive fluorescence was significantly reduced in DiOHF-treated eyes compared to the other groups, indicating a decrease in oxidative stress. A reduction in expression of α-SMA and CD31 was seen in DiOHF-treated conjunctiva compared to those treated with vehicle. Concordant results were demonstrated in cultured HTFs in vitro. Furthermore, treatment of cultured HTFs with DiOHF also displayed a reduction in the proliferation, migration, and contractility of HTFs.

Conclusions

Treatment with DiOHF reduces scarring and angiogenesis in the conjunctiva of mice with GFS at a level comparable to MMC. The reduction in oxidative stress suggests that DiOHF may suppress scarring via different mechanisms from MMC.

Translational Relevance

DiOHF may be a safer and superior wound modulating agent than conventional antifibrotic therapy in GFS.

Efficacy of nivolumab and temozolomide in advanced neuroendocrine neoplasms (NENs) in a phase 2 clinical trial

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Background: Treatment options are limited in patients with metastatic NEN. Temozolomide (TEM) alone and in combination with capecitabine is active in NEN and has been shown to have immunomodulatory impact. Here we present the final results for the NEN cohort of a phase 2 trial of combination nivolumab and TEM in patients with advanced NEN along with observed peripheral immune changes. Methods: NCT03728361 is a non-randomized, two-cohort, open-label phase 2 trial of nivolumab and TEM in patients with metastatic NEN and small cell lung cancer. The NEN cohort enrolled patients with tumors of any WHO grade, location, and line of therapy; all patients had evidence of progression prior to study. Prior immunotherapy was not allowed. Treatment consisted of nivolumab 480 mg IV on day 1 and TEM 150 mg/m2 on days 1-5 of a 28-day cycle. The primary objective was efficacy measured as response rate (RR) by RECIST v1.1. Secondary objectives were progression free survival (PFS) and overall survival (OS), by the method of Kaplan–Meier. The translational objective was to analyze peripheral blood mononuclear cells (PBMCs) collected at screening (baseline) and on cycle 1, day 15 (C1D15) via mass cytometry. Results: The RR was 36% (n=10/28, 95% CI: 18.6%-55.9%), including 10 patients (36%) with PR, 16 (57%) with SD, and 2 (7%) with PD (Table). The disease control rate was 93%. Responses occurred across all WHO grades; 44% of patients with tumors with Ki-67 >20% had PR. There was a significant difference in ORR by primary tumor location (bronchial vs pancreas vs other, p=0.004). There was no significant difference in response by Ki-67% (p=0.872), or in patients treated as first line (31%) or beyond (40%, p=0.706). The median PFS was 8.9 months (95% CI: 3.9 – 11.1 months), and median OS was not reached (95% CI: 20.7 – NR months). Two immune related SAE’s occurred: myocarditis and diarrhea in one patient each; gr4 toxicities included neutropenia (10%) and thrombocytopenia (7%). Profiling of PBMCs revealed no correlation of baseline MDSC levels with clinical benefit, however significant changes within the T cell landscape, including a decrease in CD4+ T cells (59.6% ±13.08 vs. 56.5% ±13.01, p=0.001) and increase in CD8+ T cells (27.9% ±13.36 vs. 31.7% ±14.57, p=0.03) were observed. Conclusions: Combination nivolumab and TEM demonstrated promising efficacy in patients with NENs; median OS has not been reached. Clinical trial information: NCT03728361. [Table: see text]

A randomized study of temozolomide or temozolomide and capecitabine in patients with advanced pancreatic neuroendocrine tumors: Final analysis of efficacy and evaluation of MGMT (ECOG-ACRIN E2211)

4004

Background: Patients with advanced pancreatic neuroendocrine tumors (NETs) have few treatment options that yield objective tumor response. Retrospective and small, prospective studies suggest that the combination of capecitabine and temozolomide is associated with high response rates (RR) and relative long progression-free survival (PFS). This trial was conducted to establish a role for the combination of capecitabine and temozolomide. Methods: E2211 was a multicenter, randomized, phase II trial comparing temozolomide (200 mg/m2 PO QD days 1-5) vs. capecitabine/temozolomide (capecitabine 750 mg/m2 PO BID days 1-14; temozolomide 200 mg/m2 PO QD days 10-14) in patients with advanced pancreatic NETs. Eligibility criteria included: metastatic or unresectable, low or intermediate grade pancreatic NETs, progression within preceding 12 months, and no prior temozolomide, DTIC, capecitabine or 5-fluorouracil. The primary endpoint was PFS; secondary endpoints were Overall Survival (OS), RR, safety, and MGMT as evaluated by immunohistochemistry (IHC) and promoter methylation. Allowing for 5% ineligibility, 145 randomized patients were required to obtain 138 eligible patients to detect a difference in median PFS of 9 versus 14 months (hazard ratio of 0.64) using a two-sided log-rank test at the overall 0.20 significance level with 81% power. Results: 144 patients were enrolled between 4/2013 to 3/2016 to temozolomide (n = 72) or capecitabine/temozolomide (n = 72); the efficacy analysis population included 133 eligible patients. At the scheduled interim analysis in January 2018, median PFS was 14.4 months for temozolomide vs. 22.7 months for capecitabine/temozolomide (HR = 0.58), which was sufficient to reject the null hypothesis for this final primary endpoint (stratified log rank p = 0.022. In the final analysis (5/2021), median OS was 53.8 months for temozolomide and 58.7 months for capecitabine/temozolomide (HR = 0.82, p = 0.42) and RR was 34% for temozolomide and 40% for capecitabine/temozolomide (p = 0.59). Capecitabine/temozolomide was associated with higher rates of grade 3-4 AEs (45% vs. 22%, p = 0.005). MGMT deficiency, defined as either low IHC or positive promoter methylation, was associated with greater odds of response (OR [95% CI] = 6.38 [2.19, 18.60] and 9.79 [1.09, 87.71], respectively). Conclusions: E2211 is the first prospective randomized trial of capecitabine/temozolomide and shows the longest PFS and highest RR reported for patients with pancreatic NETs in a prospective randomized study. MGMT deficiency was associated with greater odds of objective response. Clinical trial information: NCT01824875.

Association of LAG-3 expression in circulating T cells and response to combination temozolomide (TMZ) and nivolumab (NIVO) in advanced neuroendocrine neoplasms (NENs): Results from an investigator-initiated phase 2 trial

4123

Background: LAG-3 is an immune checkpoint present on NK cells, activated T cells and myeloid cells that inhibit T cell responses. Recent evidence demonstrating the safety and efficacy of LAG-3 inhibition has increased interest in this pathway for the treatment of multiple malignancies but the role in NEN is unclear. We present results from correlative peripheral blood mass cytometry (CyTOF) performed in a phase 2 trial (NCT03728361) of the combination of NIVO and TMZ in pts with advanced NEN. Methods: Patients (pts) with progressive NEN of any grade or primary location and any line of therapy were eligible. Small cell lung cancer was excluded. Clinical results from NCT03728361 will be presented in a separate abstract. Study treatment consisted of NIVO 480 mg IV every 4 weeks and TMZ 150 mg/m2 for 5 consecutive days out of a 28-day cycle. Peripheral blood mononuclear cells (PBMCs) were available from 16 out of 28 patients at screening (baseline) and cycle 1, day 15 (C1D15) and analyzed via CyTOF. Antibody labelling was performed using a 37 marker Maxpar Direct Immune Profiling Assay (Fluidigm). Immune cell populations were compared using two sample t-tests between pts with partial response (PR) and non-partial response (non-PR). Results: At screening, no differences were observed in PD-1, TIM3, or KLRG1 positive T-cell populations between pts with PR or non-PR. Patients with a PR had a significantly lower % of LAG-3 expressing T cells (p=0.029). There was a trend towards a lower % CD8+LAG-3+ T cells in pts with PR (p=0.086). At C1D15: The % of CD8+ LAG-3+ T cells were significantly higher in PRs vs. non-PR (p = 0.015). In matched samples comparing T cell populations at screening to C1D15, LAG-3+ CD8+ T cells increased significantly in PRs when compared to non-PRs (p=0.021). Conclusions: The % of LAG-3+ T cell population at baseline associates with non-response to TMZ/NIVO in NENs. Among responders, there was a significant increase in CD8+ LAG-3+ T cells by Day 15 compared to baseline indicating a potential mechanism of immune escape and eventual resistance. Clinical trial information: NCT03728361. [Table: see text]

RAC1 Alterations Induce Acquired Dabrafenib Resistance in Association with Anaplastic Transformation in a Papillary Thyroid Cancer Patient

BRAF-activating mutations are the most frequent driver mutations in papillary thyroid cancer (PTC). Targeted inhibitors such as dabrafenib have been used in advanced BRAF-mutated PTC; however, acquired resistance to the drug is common and little is known about other effectors that may play integral roles in this resistance. In addition, the induction of PTC dedifferentiation into highly aggressive KRAS-driven anaplastic thyroid cancer (ATC) has been reported. We detected a novel RAC1 (P34R) mutation acquired during dabrafenib treatment in a progressive metastatic lesion with ATC phenotype. To identify a potential functional link between this novel mutation and tumor dedifferentiation, we developed a cell line derived from the metastatic lesion and compared its behavior to isogenic cell lines and primary tumor samples. Our data demonstrated that RAC1 mutations induce changes in cell morphology, reorganization of F-actin almost exclusively at the cell cortex, and changes in cell adhesion properties. We also established that RAC1 amplification, with or without mutation, is sufficient to drive cell proliferation and resistance to BRAF inhibition. Further, we identified polyploidy of chromosome 7, which harbors RAC1, in both the metastatic lesion and its derived cell line. Copy number amplification and overexpression of other genes located on this chromosome, such as TWIST1, EGFR, and MET were also detected, which might also lead to dabrafenib resistance. Our study suggests that polyploidy leading to increased expression of specific genes, particularly those located on chromosome 7, should be considered when analyzing aggressive thyroid tumor samples and in further treatments.

Neuroendocrine and Adrenal Tumors, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Neuroendocrine and Adrenal Gland Tumors focus on the diagnosis, treatment, and management of patients with neuroendocrine tumors (NETs), adrenal tumors, pheochromocytomas, paragangliomas, and multiple endocrine neoplasia. NETs are generally subclassified by site of origin, stage, and histologic characteristics. Appropriate diagnosis and treatment of NETs often involves collaboration between specialists in multiple disciplines, using specific biochemical, radiologic, and surgical methods. Specialists include pathologists, endocrinologists, radiologists (including nuclear medicine specialists), and medical, radiation, and surgical oncologists. These guidelines discuss the diagnosis and management of both sporadic and hereditary neuroendocrine and adrenal tumors and are intended to assist with clinical decision-making. This article is focused on the 2021 NCCN Guidelines principles of genetic risk assessment and counseling and recommendations for well-differentiated grade 3 NETs, poorly differentiated neuroendocrine carcinomas, adrenal tumors, pheochromocytomas, and paragangliomas.

Selpercatinib efficacy and safety in patients with RET-altered thyroid cancer: A clinical trial update

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Background: Selpercatinib, is a first-in-class, highly selective, CNS active and potent RET inhibitor approved in multiple countries for treatment of RET-fusion positive lung or thyroid cancers. Reported is an update of efficacy and safety results in RET-altered thyroid cancer, with a longer follow up (30 Mar 2020 data cutoff vs 16 Dec 2019) and additional enrolment. Methods: Patients (pts) with RET-mutant medullary thyroid cancer (MTC) and RET-fusion positive thyroid cancer (TC) were enrolled in the global (16 countries, 89 sites) Phase 1/2 LIBRETTO-001 trial (NCT03157128). The primary endpoint was objective response rate (ORR) per RECIST 1.1 by independent review committee (IRC). Secondary endpoints included duration of response (DoR), progression-free survival (PFS), clinical benefit rate (CBR; CR+PR+SD ≥16 weeks), and safety. The integrated analysis set (IAS, n = 143) includes efficacy evaluable MTC pts previously treated with cabozantinib and/or vandetanib (cabo/vande). The primary analysis set (PAS), a subset of IAS, is the first 55 enrolled pts. Cabo/vande naïve MTC pts (N = 112) and TC pts with prior systemic treatment (N = 22) were also analyzed. Safety population includes all pts who received ≥1 dose of selpercatinib (MTC N = 315; TC N = 42) by data cutoff. Results: For MTC patients, the ORR for IAS was 69.2%, in the PAS it was 69.1%, and 71.4% for cabo/vande naïve MTC pts. The ORR for TC pts (n = 22) was 77.3% (see table). Most treatment-emergent adverse events (TEAEs) were low grade; the most common (≥25% of MTC and/or TC pts treated with selpercatinib) were dry mouth, diarrhea, hypertension, fatigue and constipation for both MTC and TC pts, increased ALT/AST, peripheral edema and headache in MTC pts and nausea in TC pts. 4.8% of MTC and TC pts discontinued selpercatinib due to TEAEs but only 1.9% with MTC and none with TC discontinued due to treatment-related adverse events. Conclusions: In this updated analysis, selpercatinib continued to show marked and durable antitumor activity in pts with RET-altered thyroid cancers. Selpercatinib was well tolerated and no new safety concerns were identified. A global, randomized, phase 3 trial (LIBRETTO-531) evaluating selpercatinib compared to cabo/vande in kinase inhibitor naïve MTC pts is ongoing. Clinical trial information: NCT03157128. [Table: see text]

Efficacy of selpercatinib after prior systemic therapy in patients with RET mutant medullary thyroid cancer

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Background: Selpercatinib is a first-in-class, CNS active, highly selective, and potent RET kinase inhibitor which has demonstrated durable antitumor activity in patients (pts) with RET altered thyroid cancer and is approved in multiple countries for the treatment of RET fusion+ lung or thyroid cancers. As response rates to cancer therapy usually decline on subsequent lines of therapy, the efficacy of selpercatinib was examined in the context of the last prior therapy received before trial enrollment. Methods: Pts with RET mutant medullary thyroid cancer (MTC) previously treated with multikinase inhibitors (cabozantinib and/or vandetanib) were enrolled in the global LIBRETTO-001 trial (NCT03157128). This post-hoc exploratory intrapatient analysis, based on March 30, 2020 data cutoff date, was performed to compare the retrospective physician-reported objective response rate (ORR) from the last systemic therapy prior to enrollment, as reported in pts case reports, to ORR by independent review committee per RECIST 1.1 with selpercatinib treatment, with each patient serving as his/her own control. Results: Efficacy-evaluable pts, 64% male, 90% white with a median age of 58 years, received prior therapy for MTC (n = 143). Pts had a median of 2 (range 1-8) prior systemic regimens. The ORR on selpercatinib (69%) was markedly higher than for the last prior therapy (10%) received before enrollment. ORR improvements with selpercatinib were observed regardless of prior therapy: cabozantinib (66% vs 14%) or vandetanib (71% vs 12%). Fewer pts had progressive disease as their best overall response with selpercatinib (2/143; 1.4%) compared to last prior therapy (33/143; 23.1%). Notably selpercatinib achieved 62% ORR in pts that did not respond to their previous line of therapy prior to enrolment. This shift from non-responder to responder on selpercatinib therapy was consistent regardless of prior cabozantinib or vandetanib treatment, where pts achieved 57% and 61% ORR respectively when subsequently treated with selpercatinib. In contrast, only 3% of patients did not respond to selpercatinib after a previous response to the immediate prior therapy. Similarly, 5% and 2% of patients were non-responders on selpercatinib after a prior response with cabozantinib and vandetanib therapy respectively. Conclusions: Prior to selpercatinib, response with previous multikinase therapy was rare. By contrast, selpercatinib demonstrated robust efficacy regardless of response to or specific prior therapy in pts with RET mutant MTC. Clinical trial information: NCT03157128.

Wound Healing After Alkali Burn Injury of the Cornea Involves Nox4-Type NADPH Oxidase

Purpose

Corneal injury that occurs after burning with alkali initiates wound-healing processes, including inflammation, neovascularization, and fibrosis. Excessive reactions to injury can reduce corneal transparency and thereby compromise vision. The NADPH oxidase (Nox) enzyme complex is known to be involved in cell signaling for wound-healing angiogenesis, but its role in corneal neovascularization has been little studied.

Methods

The center corneas of wild-type and Nox4 knockout (KO) mice were injured with 3 µL 1 M NaOH, while the contralateral corneas remained untouched. On day 7, mRNA expression levels of NADPH oxidase isoforms, the proangiogenic factors VEGF-A and TGFβ1, and proinflammatory genes ICAM-1 and VCAM-1 were determined. Corneal neovascularization and fibrosis were visualized using PECAM-1 antibody and picrosirius red staining, respectively, on the same day.

Results

Expressions of both Nox2 and Nox4 gene isoforms as well as the above genes were markedly increased in the injured corneas at 7 days. Injured corneas showed neovascularization and fibrosis as well as an increase in clinical opacity score. All responses stimulated by alkali burn were abrogated in Nox4 KO mice.

Conclusions

Nox4 could be a new target to treat pathologic corneal wound-healing responses and such targeting might prevent blindness caused by burn injuries.

Emerging drugs for the treatment of adrenocortical carcinoma

Introduction: Adrenocortical cancer (ACC) is a rare and aggressive disease with a median survival of 14-17 months and 5-year survival of around 20% for advanced disease. Emerging evidence of sub-groups of ACC with specific molecular drivers indicate ACC may be amenable to inhibition of receptor tyrosine kinases involved in growth and angiogenic signaling. A significant subset of patients may also be responsive to immune strategies.Areas covered: This review outlines approaches of targeting upregulated growth pathways including Insulin-like Growth Factor, Vascular Endothelial Growth Factor, Fibroblast Growth Factor and Epidermal Growth Factor Receptor in ACC. Data of immune checkpoint blockade with nivolumab, ipilimumab, pembrolizumab and avelumab is explored in detail. Genomic studies indicate that up to 40% of ACC are driven by dysregulated WNT and glucocorticoid signaling, special focus is placed on emerging drugs in these pathways.Expert opinion: Progress in the treatment of ACC has faced challenges stemming from the rarity of the disease. Given recent advances in the understanding of the molecular pathogenesis of ACC, a window of opportunity has now opened to make significant progress in developing therapeutic options that target key pathways such as excessive glucocorticoid signaling, WNT signaling, cell cycle and immune checkpoints.

Recurrence Patterns After Surgical Resection of Gastroenteropancreatic Neuroendocrine Tumors: Analysis From the National Comprehensive Cancer Network Oncology Outcomes Database

OBJECTIVE

Current National Comprehensive Cancer Network guidelines for gastroenteropancreatic neuroendocrine tumors (GEPNETs) recommend complete (R0) surgical resection of the primary tumor and metastases, if feasible. However, large multicenter studies of recurrence patterns of GEPNETs after resection have not been performed.

METHODS

Patients 18 years or older who presented to 7 participating National Comprehensive Cancer Network institutions between 2004 and 2008 with a new diagnosis of a small bowel, pancreas, or colon/rectum neuroendocrine tumor (NET) and underwent R0 resection of the primary tumor, and synchronous metastases, if present, were included in this analysis. Descriptive statistics and Kaplan-Meier estimates were used to calculate recurrence rates and time-associated end points, respectively.

RESULTS

Of 294 patients with GEPNETs, 50% were male, 88% were White, and 99% had Eastern Cooperative Oncology Group performance status 0 to 1. The median age was 55 years (range, 20-90). The median follow-up time from R0 resection was 62.1 months. Recurrence rates were 18% in small bowel NETs (n = 110), 26% in pancreatic NETs (n = 141), and 10% in colon/rectum NETs (n = 50). The frequency of surveillance imaging was highly variable.

CONCLUSIONS

R0 resection was associated with variable risk of recurrence across subtypes. Further research to inform refinement of guidelines for the appropriate duration of surveillance after R0 resection is needed.

Co-occurrence of multiple endocrine neoplasia type 4 and spinal neurofibromatosis: a case report

Multiple Endocrine Neoplasia (MEN) type 4 is a rare genetic condition that results from variants of the CDKN1B gene and predisposes individuals to develop endocrine tumors. Spinal neurofibromatosis (SNF) is an uncommon subtype of neurofibromatosis type 1 (NF1) characterized by bilateral neurofibromas of all spinal roots. Here we report a case of the co-occurrence of these syndromes, which has not yet been described in the literature. A male in his 60s presented with Gleason 5 + 4 localized prostate adenocarcinoma treated with radical prostatectomy. Two years later, he developed liver and bone metastasis consistent with trans-differentiation into small cell carcinoma. He developed hypercalcemia due to primary hyperparathyroidism from a parathyroid adenoma treated surgically. His family history was significant for a first-degree relative with a clinical diagnosis of NF1 and several second-degree relatives with multiple café-au-lait macules. Spine MRI showed multiple bilateral neurofibromas. Germline genetic testing showed a pathogenic variant in the CDKN1B gene, a variant in the NF1 gene, and a normal MEN1 gene. In this rare case of MEN4 and SNF, the patient was asymptomatic for much of his life. In addition to parathyroid adenoma and spinal neurofibromas, he had prostate adenocarcinoma with trans-differentiation into metastatic small cell cancer. Whether this diagnosis was coincidental or related to an emerging phenotype remains to be elucidated.

Oxidative Stress and the Role of NADPH Oxidase in Glaucoma

Glaucoma is characterised by loss of retinal ganglion cells, and their axons and many pathophysiological processes are postulated to be involved. It is increasingly understood that not one pathway underlies glaucoma aetiology, but rather they occur as a continuum that ultimately results in the apoptosis of retinal ganglion cells. Oxidative stress is recognised as an important mechanism of cell death in many neurodegenerative diseases, including glaucoma. NADPH oxidase (NOX) are enzymes that are widely expressed in vascular and non-vascular cells, and they are unique in that they primarily produce reactive oxygen species (ROS). There is mounting evidence that NOX are an important source of ROS and oxidative stress in glaucoma and other retinal diseases. This review aims to provide a perspective on the complex role of oxidative stress in glaucoma, in particular how NOX expression may influence glaucoma pathogenesis as illustrated by different experimental models of glaucoma and highlights potential therapeutic targets that may offer a novel treatment option to glaucoma patients.

Efficacy of Selpercatinib in RET Fusion-Positive Non-Small-Cell Lung Cancer

BACKGROUND

RET fusions are oncogenic drivers in 1 to 2% of non-small-cell lung cancers (NSCLCs). In patients with RET fusion-positive NSCLC, the efficacy and safety of selective RET inhibition are unknown.

METHODS

We enrolled patients with advanced RET fusion-positive NSCLC who had previously received platinum-based chemotherapy and those who were previously untreated separately in a phase 1-2 trial of selpercatinib. The primary end point was an objective response (a complete or partial response) as determined by an independent review committee. Secondary end points included the duration of response, progression-free survival, and safety.

RESULTS

In the first 105 consecutively enrolled patients with RET fusion-positive NSCLC who had previously received at least platinum-based chemotherapy, the percentage with an objective response was 64% (95% confidence interval [CI], 54 to 73). The median duration of response was 17.5 months (95% CI, 12.0 to could not be evaluated), and 63% of the responses were ongoing at a median follow-up of 12.1 months. Among 39 previously untreated patients, the percentage with an objective response was 85% (95% CI, 70 to 94), and 90% of the responses were ongoing at 6 months. Among 11 patients with measurable central nervous system metastasis at enrollment, the percentage with an objective intracranial response was 91% (95% CI, 59 to 100). The most common adverse events of grade 3 or higher were hypertension (in 14% of the patients), an increased alanine aminotransferase level (in 12%), an increased aspartate aminotransferase level (in 10%), hyponatremia (in 6%), and lymphopenia (in 6%). A total of 12 of 531 patients (2%) discontinued selpercatinib because of a drug-related adverse event.

CONCLUSIONS

Selpercatinib had durable efficacy, including intracranial activity, with mainly low-grade toxic effects in patients with RET fusion-positive NSCLC who had previously received platinum-based chemotherapy and those who were previously untreated. (Funded by Loxo Oncology and others; LIBRETTO-001 ClinicalTrials.gov number, NCT03157128.).

Efficacy of Selpercatinib in RET-Altered Thyroid Cancers

BACKGROUND

RET mutations occur in 70% of medullary thyroid cancers, and RET fusions occur rarely in other thyroid cancers. In patients with RET-altered thyroid cancers, the efficacy and safety of selective RET inhibition are unknown.

METHODS

We enrolled patients with RET-mutant medullary thyroid cancer with or without previous vandetanib or cabozantinib treatment, as well as those with previously treated RET fusion-positive thyroid cancer, in a phase 1-2 trial of selpercatinib. The primary end point was an objective response (a complete or partial response), as determined by an independent review committee. Secondary end points included the duration of response, progression-free survival, and safety.

RESULTS

In the first 55 consecutively enrolled patients with RET-mutant medullary thyroid cancer who had previously received vandetanib, cabozantinib, or both, the percentage who had a response was 69% (95% confidence interval [CI], 55 to 81), and 1-year progression-free survival was 82% (95% CI, 69 to 90). In 88 patients with RET-mutant medullary thyroid cancer who had not previously received vandetanib or cabozantinib, the percentage who had a response was 73% (95% CI, 62 to 82), and 1-year progression-free survival was 92% (95% CI, 82 to 97). In 19 patients with previously treated RET fusion-positive thyroid cancer, the percentage who had a response was 79% (95% CI, 54 to 94), and 1-year progression-free survival was 64% (95% CI, 37 to 82). The most common adverse events of grade 3 or higher were hypertension (in 21% of the patients), increased alanine aminotransferase level (in 11%), increased aspartate aminotransferase level (in 9%), hyponatremia (in 8%), and diarrhea (in 6%). Of all 531 patients treated, 12 (2%) discontinued selpercatinib owing to drug-related adverse events.

CONCLUSIONS

In this phase 1-2 trial, selpercatinib showed durable efficacy with mainly low-grade toxic effects in patients with medullary thyroid cancer with and without previous vandetanib or cabozantinib treatment. (Funded by Loxo Oncology and others; LIBRETTO-001 ClinicalTrials.gov number, NCT03157128.).

Abstract 4481: Effect of immune checkpoint blockade on myeloid derived suppressor cell populations in patients with melanoma

Introduction: Myeloid derived suppressor cells (MDSC) are a subset of immature myeloid cells that inhibit innate anti-tumor immunity and promote an immunosuppressive tumor microenvironment. MDSC quantity has been correlated with tumor burden and survival in cancer patients. These cells have the potential to contribute to immune therapy resistance. The purpose of this study was to elucidate the ongoing changes to MDSC populations in patients with advanced melanoma as they receive immune checkpoint therapy.

Methods: Patients with melanoma (n=125) were consented to participate in an IRB-approved prospective clinical registry (OSU-13114), and provided blood samples. Samples were drawn at the time of initiation of immune checkpoint therapy (cycle 1), and prior to the beginning of cycles 2 and 3. Samples were then processed using Ficoll and analyzed for MDSC (CD33+/CD11b+/HLA-DRlo/−) and MDSC subsets, monocyte (CD14+, M-MDSC) and granulocytic (CD15+, PMN-MDSC) via flow cytometry. Patient demographics were compiled into a comprehensive database and correlated to the flow cytometry data. Statistical analysis was performed using unpaired and paired t-tests across and within patient cohorts.

Results: Total MDSC percentages increased following initiation of immune checkpoint blockade (10 to 25%, p&lt;0.0001). MDSC levels in patients who had complete or partial response began to taper (10% to 26% to 25%), whereas MDSC levels in those who had progressive disease on immunotherapy continued to increase (11% to 16% to 19%). PMN-MDSC significantly decreased after immunotherapy (19% to 10%, p=0.0423). Specifically, patients who received Pembrolizumab had a significant decrease in PMN-MDSC proportion (11% to 2%, p=0.04). A decrease in PMN-MDSC proportion was also noted with Nivolumab (21% to 16%, p=0.097). Patients who had received immune therapy prior to this trial had less PMN-MDSC at baseline (21% vs 12%, p=0.09), and significantly less PMN-MDSC following immune checkpoint blockade (14% vs 2%, p=0.009).

Conclusions: MDSC levels initially increase following immune checkpoint blockade, but stabilize in responders and continue to rise in non-responders. The proportion of PMN-MDSC decreases with immune checkpoint blockade, most significantly seen with pembrolizumab. Patients who have been previously treated with immune therapy have a more significant decrease in PMN-MDSC.

Citation Format: Steven Hao Sun, Brooke Benner, Himanshu Savardekar, Mallory DiVincenzo, David Abood, Andrew Stiff, Megan Duggan, Erin Nagle, John H. Howard, Manisha H. Shah, Kari Kendra, William E. Carson. Effect of immune checkpoint blockade on myeloid derived suppressor cell populations in patients with melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4481.

KRAS G12V Mutation in Acquired Resistance to Combined BRAF and MEK Inhibition in Papillary Thyroid Cancer

BRAF V600E mutations occur in approximately 40% of all patients with papillary thyroid cancer (PTC) and are associated with a worse prognosis in population studies. Treatment with single-agent BRAF inhibitors can result in nondurable partial responses (PRs) in clinical trials, but resistance inevitably develops. The mechanisms of resistance are not completely understood, but in non-thyroid tumors harboring BRAF V600E mutations, resistance has been ascribed to concurrent or acquired mutations in MEK1/2, RAC1, KRAS, and NRAS. This case report describes a patient with radioactive iodine-refractory metastatic PTC treated in a clinical trial with combination BRAF and MEK inhibition who achieved a durable PR. At time of progression, biopsy revealed an acquired KRAS G12V-activating mutation. The patient subsequently went on to have a PR to cabozantinib therapy in the clinical trial. This is the first reported case of an acquired KRAS-activating mutation that developed during treatment with BRAF and MEK inhibition in a patient with BRAF-mutated PTC. The KRAS mutation was also detected in peripheral blood samples taken as part of the trial, indicating that resistant mutations may be identified through noninvasive means. The identification of resistant mutations in patients at time of progression is necessary to identify possible therapeutic options including potential clinical trials.ClinicalTrials.gov identifier: NCT01723202.

Selpercatinib (LOXO-292) in patients with RET-mutant medullary thyroid cancer

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Background: Selpercatinib (LOXO-292) is a highly selective and potent small molecule RET kinase inhibitor. Here we report an update on the efficacy and safety of selpercatinib in RET-mutant medullary thyroid cancer (MTC). Methods: Patients with RET-mutant MTC were enrolled to the Phase 1/2 LIBRETTO-001 trial (NCT03157128), a global, multicenter trial (16 countries, 89 sites). Following the Phase 1 dose escalation portion of the trial, patients received the recommended dose of 160 mg orally twice daily. Each cycle was 28 days. The primary endpoint was objective response rate (ORR) per RECIST 1.1. Secondary endpoints included duration of response (DoR) and safety. Per health authority agreement, the primary analysis set was defined as the first 55 consecutively enrolled patients previously treated with multikinase inhibitors cabozantinib and/or vandetanib. Patients naïve to cabozantinib and vandetanib treatment were analyzed separately. All analyses were based on a 16-Dec-2019 data cutoff date. Results: In the primary analysis set of prior cabozantinib and/or vandetanib-treated patients with MTC (n = 55), the ORR by investigator assessment was 62% (95% CI 47.7–74.6, n = 34/55) and the median DoR was not reached (95% CI 18.4 months–not estimable) despite a median follow-up of 14.8 months. In cabozantinib/vandetanib treatment-naïve patients (n = 88), the ORR by investigator assessment was 69% (95% CI 58.6–78.7, n = 61/88, including 2 responses pending confirmation). Of the 59 confirmed responding patients, with a median follow-up of 8 months, responses were ongoing for 57 responders at the time of the analysis. In the safety analysis set consisting of all selpercatinib dosed patients (N = 702), the most common treatment-related adverse events (TRAEs) that occurred in ≥15% of patients were dry mouth (33.3%), increased AST (24.5%), increased ALT (23.8%), hypertension (23.2%), diarrhea (19.7%), and fatigue (16.8%). Only 2% (14 of 702) of patients discontinued selpercatinib for TRAEs. Conclusions: Selpercatinib use was associated with marked and durable antitumor activity in prior cabozantinib and/or vandetanib-treated patients and in cabozantinib/vandetanib-naïve patients with RET-mutant MTC, with the majority of responses ongoing in both cohorts. Selpercatinib was well tolerated. Efficacy data assessed by independent review committee based on the 16-Dec-2019 data cutoff date will be presented. Clinical trial information: NCT03157128 .

A pilot study of Bruton’s tyrosine kinase inhibitor ibrutinib alone and in combination with PD-1 inhibitor nivolumab in patients with metastatic solid tumors

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Background: Myeloid-derived suppressor cells (MDSC) are expanded in cancer and promote immune suppression. We have shown that ibrutinib inhibits migration and immunosuppressive function of MDSC. Moreover, the combination of ibrutinib and a PD-L1 inhibitor has been found to have synergistic anti-tumor effects in a multiple solid tumor mouse models. Therefore, we conducted a pilot study testing the combination of ibrutinib and nivolumab in patients with metastatic solid tumors. Methods: Sixteen patients with advanced solid tumors were recruited to this trial. Ibrutinib was dosed as an oral single agent, starting 7 days prior to cycle 1 of nivolumab and given until cycle 1, day 8 of nivolumab. Nivolumab was administered intravenously on days 1 and 15 on 28-day cycles. Patients had blood samples collected prior to initiation of ibrutinib, day 1 of cycle 1, day 8 of cycle 1, day 1 of cycle 2, and at the time of disease progression. From these specimens, we measured circulating MDSC levels, other circulating immune subsets, T cell proliferation, and cytokines/chemokines levels. Circulating MDSC levels were measured by mass spectrometry. T cell function was evaluated by CFSE to monitor proliferating cells by dye dilution and cytokine/chemokine levels were measured with a U-PLEX assay. Data were analyzed using two-tailed, paired Student's t-tests to assess statistical significance. Results: An increase in circulating MDSC (22% to 28%; SD 9.158) levels was observed following 7 days of single-agent ibrutinib compared to baseline. However, in combination therapy, MDSC levels decreased (19%; SD 13.17) prior to cycle 2. Despite increasing levels of circulating MDSC, T cell function improved throughout the study. Furthermore, plasma levels of chemokines associated with MDSC recruitment and migration significantly decreased with ibrutinib treatment (IL-12, CCL2, CCL3, and CCL4). Of the 16 patients, four achieved a partial response and four achieved stable disease. Median progression free survival was 3.5 months and median overall survival was 11.5 months. Conclusions: The combination of ibrutinib and nivolumab was well tolerated, demonstrated early signs of immune modulation, and showed preliminary signs of promising clinical activity in patients with metastatic solid tumors. Clinical trial information: NCT03525925 .

SUN-LB75 The Anti-Tumor Activity of the Selective Ret Inhibitor Selpercatinib (LOXO-292) in Medullary Thyroid Cancer Is Independent of the Specific RET Mutation

The RET receptor tyrosine kinase proto-oncogene is activated by somatic or germline mutations in a majority of medullary thyroid cancers (MTC). However, treatment of MTC has been challenging due to the lack of effective and tolerable RET-specific therapy, thus testing tumors for the presence of somatic RET mutation has not been warranted. In a first-in-human, phase 1/2 clinical trial (LIBRETTO-001, NCT03157128), selpercatinib (LOXO-292), an investigational, highly selective, potent small molecule RET kinase inhibitor, demonstrated significant and durable anti-tumor activity in patients with advanced RET-mutant MTC or with diverse RET fusion-positive cancers (1). Among the primary analysis set of patients with RET-mutant MTC previously treated with cabozantinib and/or vandetanib (N=55), the investigator-assessed objective response rate (ORR) per RECIST 1.1 was 56% (95% CI 42.3-69.7, n=31/55). Duration of response was not reached with a 10.6-months median follow-up (data cutoff date 17-Jun-2019). Here, we evaluated investigator-assessed ORR per RECIST 1.1 and clinical benefit rate (CBR) in this previously treated patient population by RET alteration and by germline or somatic testing used for enrollment. The ORR remained consistent across subgroups with RET M918T (49%, 95% CI 30.8-66.5, n=16/33), V804M/L gatekeeper mutations (60%, 95% CI 14.7-94.7, n=3/5), extracellular cysteine mutations (43%, 95% CI 9.9-81.6, n=3/7), other mutations (90%, 95% CI 55.5-99.7, n=9/10), and germline (50%, 95% CI 6.8-93.2, n=2/4) or somatic (57%, 95% CI 42.2-70.7, n=29/51) testing. The CBR, defined as the proportion of patients with best overall response of confirmed complete response, confirmed or unconfirmed partial response, or stable disease lasting 16 weeks or more, in this patient set was 87% (95% CI 75.5-94.7, n=48/55). The CBR remained consistent across subgroups with RET M918T (88%, 95% CI 71.8-96.6, n=29/33), V804M/L gatekeeper mutations (80%, 95% CI 28.4-99.5, n=4/5), extracellular cysteine mutations (71%, 95% CI 29.0-96.3, n=5/7), other mutations (100%, 95% CI 69.2-100.0, n=10/10), and germline (75%, 95% CI 19.4-99.4, n=3/4) or somatic (88%, 95% CI 76.1-95.6, n=45/51) testing. The primary technologies used to identify RET alterations were tumor next-generation sequencing (n=43) and polymerase chain reaction (n=9). As previously reported, selpercatinib was well tolerated with an acceptable safety profile (1). These results indicate broad anti-tumor activity for selpercatinib in patients with RET-mutant MTC irrespective of the specific RET mutation, and support implementation of RET mutation testing for patients with advanced MTC, including somatic testing, to identify patients who may benefit from selpercatinib. Reference: (1) Wirth et al., Ann Oncol. 2019 Oct; 30(supplement 5): v933.

Pembrolizumab for advanced anal squamous cell carcinoma (ASCC): Results from the multicohort, phase II KEYNOTE-158 study

1

Background: For patients (pts) with ASCC, second-line or later treatment options have been limited. Pembrolizumab (pembro), an anti-PD-1 monoclonal antibody, has demonstrated antitumor activity in several tumor types (including ASCC) in the multicohort phase 1b KEYNOTE-028 study. KEYNOTE-158 (NCT02628067) is an open-label, phase 2, multicohort study that evaluates antitumor activity and safety of pembro in pts with previously treated advanced cancer. Results from the ASCC cohort are presented. Methods: Eligible pts were ≥18 y with histologically/cytologically documented metastatic and/or unresectable ASCC with prior treatment failure on or intolerance to standard first-line therapy, measurable disease per RECIST v1.1, ECOG PS of ≤1, and evaluable tissue sample for PD-L1 and biomarker analysis. PD-L1 expression was assessed by the PD-L1 IHC 22C3 pharmDx assay (Agilent Technologies). Pts received pembro 200 mg Q3W until disease progression, unacceptable AE, or completion of 35 cycles. The primary endpoint was ORR per RECIST v1.1 (assessed every 9 wk for 12 mo, then every 12 wk thereafter) by independent central review. Secondary endpoints were DOR, OS, PFS and safety. Results: 112 pts with ASCC were enrolled (81.3% women; median age, 61 y [range 32–79]; ≥2 prior therapies, 73.2%). At database cutoff (Dec 6, 2018) 10 pts (8.9%) had completed 35 cycles and 102 discontinued; median follow-up was 12.0 mo (range, 0.8–33.0) Five pts had CR and 8 had PR; ORR was 11.6% (95% CI, 6.3–19.0). Median DOR was not reached (range, 6.0+ to 29.1+ mo). Responses occurred in 11/75 pts (14.7%) with PD-L1 combined positive score (CPS) ≥1 and 2/30 pts (6.7%) with PD-L1 CPS < 1. Among all pts, median OS was 12.0 mo (95% CI, 9.1–15.4), and median PFS was 2.0 mo (95% CI, 2.0–2.1). 68 (60.7%) pts had treatment-related AEs, including 21 (18.8%) who had grade 3–5 events; there were no treatment-related deaths. 4 pts (3.6%) discontinued due to treatment-related AEs. 27 pts (24.1%) had immune-mediated AEs/infusion reactions. Conclusions: Pembro demonstrated antitumor activity and manageable toxicity in pts with heavily pretreated advanced ASCC, regardless of PD-L1 status. Clinical trial information: NCT02628067.

A Phase II Basket Trial of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART SWOG 1609) in Patients with Nonpancreatic Neuroendocrine Tumors

PURPOSE

Immune checkpoint blockade has improved outcomes across tumor types; little is known about the efficacy of these agents in rare tumors. We report the results of the (nonpancreatic) neuroendocrine neoplasm cohort of SWOG S1609 dual anti-CTLA-4 and anti-PD-1 blockade in rare tumors (DART).

PATIENTS AND METHODS

We performed a prospective, open-label, multicenter phase II clinical trial of ipilimumab plus nivolumab across multiple rare tumor cohorts, with the (nonpancreatic) neuroendocrine cohort reported here. Response assessment by grade was not prespecified. The primary endpoint was overall response rate [ORR; RECIST v1.1; complete response (CR) and partial response (PR)]; secondary endpoints included progression-free survival (PFS), overall survival (OS), stable disease >6 months, and toxicity.

RESULTS

Thirty-two eligible patients received therapy; 18 (56%) had high-grade disease. Most common primary sites were gastrointestinal (47%; N = 15) and lung (19%; N = 6). The overall ORR was 25% [95% confidence interval (CI) 13-64%; CR, 3%, N = 1; PR, 22%, N = 7]. Patients with high-grade neuroendocrine carcinoma had an ORR of 44% (8/18 patients) versus 0% in low/intermediate grade tumors (0/14 patients; P = 0.004). The 6-month PFS was 31% (95% CI, 19%-52%); median OS was 11 months (95% CI, 6-∞). The most common toxicities were hypothyroidism (31%), fatigue (28%), and nausea (28%), with alanine aminotransferase elevation (9%) as the most common grade 3/4 immune-related adverse event, and no grade 5 events.

CONCLUSIONS

Ipilimumab plus nivolumab demonstrated a 44% ORR in patients with nonpancreatic high-grade neuroendocrine carcinoma, with 0% ORR in low/intermediate grade disease.

Nivolumab in Metastatic Adrenocortical Carcinoma: Results of a Phase 2 Trial

CONTEXT

Systemic treatment of metastatic adrenocortical carcinoma (ACC) remains limited to chemotherapy and mitotane. Preliminary evidence suggesting that antitumor immune responses can be elicited in ACC has fostered interest in checkpoint inhibitors such as anti-PD-1 nivolumab.

OBJECTIVE

The primary endpoint was objective response rate according to the response evaluation criteria in solid tumors. Secondary endpoints were progression-free survival (PFS), overall survival, and safety.

DESIGN

Single-arm, multicenter, phase 2 clinical trial with two-stage design.

SETTING

Comprehensive cancer center.

PATIENTS

Ten adult patients with metastatic ACC previously treated with platinum-based chemotherapy and/or mitotane as well as patients who declined front-line chemotherapy.

INTERVENTION

Nivolumab (240 mg) IV every 2 weeks.

RESULTS

Ten patients with metastatic ACC were enrolled between March and December 2016. The median number of doses of nivolumab administered was two. Three patients only received one treatment [one died of disease progression, one discontinued due to adverse events (AEs), one withdrew after beginning treatment]. The median PFS was 1.8 months. The median follow-up was 4.5 months (range, 0.1 to 25.6 months). Two patients had stable disease for a duration of 48 and 11 weeks, respectively. One patient had an unconfirmed partial response but discontinued the study due to an AE. Most AEs were grade 1/2. The most common grade 3/4 treatment-related AEs were aspartate aminotransferase and alanine aminotransferase elevations, mucositis, and odynophagia.

CONCLUSION

Nivolumab demonstrated modest antitumor activity in patients with advanced ACC. The nivolumab safety profile was consistent with previous clinical experience without any unexpected AEs in this population.

Targeting BRAF Mutations in High-Grade Neuroendocrine Carcinoma of the Colon

Mutations in the RAS/RAF/MEK/ERK pathway leading to constitutive activation and uncontrolled cellular growth have been identified in various human malignancies, making this pathway a target for potential therapeutics. The activating BRAF^V600E mutation is one well-characterized oncogenic mutation that has been described and targeted with clinical success in various malignancies, including melanoma and hairy cell leukemia. Although BRAF-directed treatments have yielded clinical benefit in a subset of tumor types, such as melanoma, thyroid cancer, and lung cancer, BRAF inhibition fails to confer a clinical benefit in colon cancer. Identification of patients for whom BRAF inhibition may produce clinically meaningful outcomes is imperative. The incidence of BRAF mutations in neuroendocrine carcinoma (NEC) is estimated to be 5% to 10%. A recent case series demonstrated benefit in targeting the BRAF^V600E mutation in metastatic high-grade rectal NECs. Combination BRAF and MEK inhibition is known to yield improved outcomes compared with BRAF inhibition alone in melanoma. This report presents 2 patients with high-grade colorectal NECs who had different responses to treatment with combined BRAF/MEK inhibition after experiencing disease progression through first-line platinum-based chemotherapy. One patient experienced an excellent initial response to therapy before ultimately experiencing progression, and in the other patient initially had stable disease before eventually experiencing progression. These cases highlight the complicated role BRAF mutations play in gastrointestinal NECs, and the need for further research to identify not only patients who may benefit from BRAF-directed therapies but also strategies to avoid development of resistance.

The Adrenal Gland as a Sanctuary Site of Metastases After Pembrolizumab Treatment: A Case Series

Therapeutic agents targeting the PD-1/PD-L1 axis have shown durable clinical responses in patients with various cancer types. Although objective responses are common, intrapatient heterogeneous responses have been described, and the mechanism for the different organ responses remains unknown. We present a series of patients in whom a lack of response was noted solely in the adrenal glands. This is the first case series describing 3 patients with heterogeneous patterns of response to pembrolizumab with progression of adrenal metastatic disease despite objective response (complete or partial response) in all other sites of metastatic disease. Two patients, one with melanoma and one with uterine carcinosarcoma, underwent robotic adrenalectomy for enlarging adrenal metastases. An additional patient with melanoma underwent laparotomy with attempted resection, but infiltration of the adrenal tumor into the inferior vena cava prohibited safe excision. This report provides additional insight into the heterogeneous patterns of disease response to anti-PD-1 therapy, highlighting the adrenal gland as a potential sanctuary site for this immunotherapy. These cases display the potential benefit of early surgical resection in this scenario and the pitfalls of delaying referral to a surgeon for assessment of operative intervention.

NCCN Guidelines Insights: Neuroendocrine and Adrenal Tumors, Version 2.2018

The NCCN Guidelines for Neuroendocrine and Adrenal Tumors provide recommendations for the management of adult patients with neuroendocrine tumors (NETs), adrenal gland tumors, pheochromocytomas, and paragangliomas. Management of NETs relies heavily on the site of the primary NET. These NCCN Guidelines Insights summarize the management options and the 2018 updates to the guidelines for locoregional advanced disease, and/or distant metastasis originating from gastrointestinal tract, bronchopulmonary, and thymus primary NETs.

Vandetanib-induced Phototoxic Drug Eruption Treated with Polypodium Leucotomos Extract: A Case Report and Review of the Literature

Vandetanib is a tyrosine kinase inhibitor approved by the United States Food and Drug Administration for the treatment of metastatic medullary thyroid cancer. It has been linked to a variety of dermatologic reactions, including photosensitivity. We describe the case of a 55-year-old man who developed a severe, painful, erythematous, bullous eruption in sun-exposed areas one month after the initiation of vandetanib. The eruption was initially refractory to treatment with steroids and did not resolve with strict sun avoidance, but finally cleared after a few weeks of oral supplementation with Polypodium leucotomos (P. leucotomos) extract. P. leucotomos is an extract derived from a tropical fern, with antioxidant effects that mitigate ultraviolet-induced cutaneous erythema via inflammatory interference and the promotion of other cytotoxic responses. This case illustrates the potential for P. leucotomos to be used as a safe and effective photoprotective agent for refractory phototoxic reactions. Further randomized, controlled trials are needed to better understand the mechanism of action and photoprotective properties of P. leucotomos in the treatment of tyrosine kinase-induced phototoxicity and other dermatoses.

First real-world experience of peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumors (NET) since US FDA approval

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Background: PRRT using 177Lu-DOTATATE was US FDA approved in Jan 2018, and real world data in the US is lacking. Methods: We retrospectively reviewed medical records of patients who began PRRT 03/14/18 - 10/01/18 at our institution. 177Lu-DOTATATE was administered at a dose of 200mCi over 20-30 min every 8 weeks for 4 doses. Infusion of arginine-lysine 25gm/25gm in 1-liter normal saline was given over 4 hours starting 30 min prior to treatment, in addition to intravenous palonosetron 0.25mg. Results: 51 patients received at least 1 of 4 doses and 40/51 were no longer on active therapy. 28/40 received all 4 doses and 12/40 discontinued treatment after < 4 doses. 25/40 were evaluable for response per RECIST v1.1. 16/25 (64%) had GI NET, 3/25 (12%) pancreatic NET, 4/25 (16%) atypical lung carcinoid, 1/25 (4%) multifocal NET, and 1/25 (4%) had paraganglioma. 28% had grade 1, 56% grade 2, and 8% (2/25) had grade 3 (Ki 67: 25% and 40%) NET. 12/25 (48%) had received ≥2 prior systemic therapies not including somatostatin analogs, and 10/25 (40%) had ≥1 prior liver-directed therapy. Median follow-up from date of last PRRT was 61.5 days. Objective response (partial response) rate was 16% (4/25; table). 18/25 (72%) had stable disease and 3/25 (12%) had progressive disease. Most adverse events (AEs) were grade 1-2 and included fatigue, nausea, abdominal pain, and cytopenias. ≥Grade 3 AEs requiring treatment discontinuation included symptomatic gastric outlet obstruction (2/51), small bowel obstruction (1/51), ischemic enteritis (1/51), confusion/bone pains (1/51), liver failure (1/51), and severe neutropenia (1/51). All patients with ≥grade 3 AEs had a high tumor burden at baseline. Conclusions: 177Lu-DOTATATE is an effective and safe treatment in advanced NET, and our results are consistent with NETTER 1 data.[Table: see text]

Pembrolizumab treatment of advanced neuroendocrine tumors: Results from the phase II KEYNOTE-158 study

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Background: Data from the KEYNOTE-028 study (NCT02054806) suggested that pembrolizumab (pembro) has clinical activity in a subset of patients (pts) with heavily pretreated neuroendocrine tumors (NET). The KEYNOTE-158 study (NCT02628067) is a phase II basket study investigating the antitumor activity of pembro in 10 specific cancer types. An analysis of the 107 pts included in the NET cohort is presented. Methods: Key eligibility criteria for this cohort included well- and moderately-differentiated NET of the lung, appendix, small intestine, colon, rectum, or pancreas; progression on or intolerance to ≥ 1 line of standard therapy; ECOG PS 0 or 1; and provision of a tumor sample for biomarker analysis. Pts received pembrolizumab 200 mg Q3W for 2 y or until progression, intolerable toxicity, or physician or patient decision. Tumor imaging was performed every 9 wks for the first 12 mo, and every 12 wks thereafter. PD-L1 positivity, defined as a combined positive score (CPS) ≥ 1, was evaluated retrospectively by IHC. Primary endpoint was ORR assessed per RECIST v1.1 by independent central radiology review. Secondary endpoints included DOR, PFS, OS, and safety. Results: 107 pts were treated. Median age was 59 (range, 29-80) y, 44.9% had ECOG PS 1, and 67.3% received ≥ 2 prior therapies for advanced disease. 15.9% of enrolled pts had PD-L1+ tumors. As of the January 15, 2018 data cutoff, the median follow-up duration was 18.6 (range, 0.2-22.7) mo. ORR was 3.7% (95% CI, 1.0-9.3), with 0 CR and 4 PR (3 pancreatic and 1 gastrointestinal [unknown primary]). 61 pts had SD as best response. The 4 responses were observed in pts with PD-L1 negative tumors. Median DOR had not been reached (range, 4.1-15.9+), with 3 of 4 responses ongoing after ≥ 9 mo follow-up. Median (95% CI) PFS was 4.1 (3.5-5.4) mo, and the 6-mo PFS rate was 38.2%. Median OS (95% CI) had not been reached (18.8-not reached), and the 6-mo OS rate was 84.6%. Treatment-related AEs occurred in 75.7% of pts, and the most common was fatigue (21.5%). 20.6% of pts had treatment-related grade 3-4 AEs. Conclusions: Pembrolizumab monotherapy showed limited antitumor activity and manageable safety in pts with previously treated advanced NET. Clinical trial information: NCT02628067.

The emerging role of targeted therapies for advanced well-differentiated gastroenteropancreatic neuroendocrine tumors

INTRODUCTION

Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are unique and complex neoplasms, exhibiting a wide spectrum of diverse clinical behaviors. The contemporary management of well-differentiated GEP-NETs is marked by the availability of a wide range of targeted therapies. Areas Covered: For patients with localized or oligometastatic disease, surgical resection remains the preferred approach and is associated with excellent long-term outcomes. For patients with unresectable but isolated liver metastases, multiple liver-directed therapies, including hepatic arterial based therapies and ablative techniques, exist. For patients with metastatic and progressive disease, a number of systemic therapies exist: molecular targeted agents, peptide receptor radionuclide therapy (PRRT), and systemic chemotherapy. Furthermore, somatostatin analogs (SSA) are an important component of therapy, both effectively controlling symptoms of hormonal overproduction and contributing to slowing tumor progression. Expert Opinion: In the near future, advances in our understanding of tumor biology, genetics, immunology, nanotechnology, and radiation pharmacology should only continue to expand the availability of targeted therapies, improving the outcomes of patients with GEP-NETs. We herein review the management of advanced well-differentiated GEP-NETS with a particular emphasis on the role of targeted therapies.

Phase I Trial of Dabrafenib and Pazopanib in BRAF Mutated Advanced Malignancies

Purpose

Several tumor types carry BRAF mutations and vascular endothelial growth factor pathway upregulation. Resistance mechanisms to BRAF inhibitors can include platelet-derived growth factor-β upregulation. Dabrafenib, a BRAF inhibitor, and pazopanib, a multikinase inhibitor that targets vascular endothelial growth factor and platelet-derived growth factor, have not been combined previously. This phase I study was designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of the combination.

Patients and Methods

Patients with any advanced BRAF mutated malignancy with adequate organ function were eligible. Prior use of dabrafenib or pazopanib was not allowed. Dosages started at dabrafenib 50 mg twice a day and pazopanib 400 mg daily on dose level (DL) 1, with maximum dosages of 150 mg twice a day and 800 mg daily on DL5. Pharmacokinetics and BRAF V600E plasma clone were measured, and efficacy was evaluated by imaging and tumor markers every 8 weeks.

Results

Twenty-three patients with 11 different tumor histologies were enrolled in five DLs. Two dose-limiting toxicities were observed—a grade 3 bowel perforation on DL3 and grade 3 arthralgia on DL5. Common drug-related adverse events included nausea (52%), skin papules (43%), diarrhea (39%), hand-foot syndrome (30%), anemia (26%), rash (22%), vomiting (22%), hypophosphatemia (22%), and transaminitis (22%). Five patients (22%) experienced a partial response, including low-grade ovarian serous carcinoma, thyroid cancer, and glioblastoma multiforme, and two patients (appendiceal and thyroid cancer) had stable disease > 6 months. Pharmacokinetic measurements revealed pazopanib levels < 17.5 μg/mL in 80% of treated patients at steady state, particularly at DL5. BRAF V600E plasma copies correlated with response and progression.

Conclusion

Combination dabrafenib and pazopanib had no unexpected toxicities, and durable partial responses were observed at DL3 or greater. Dose escalation beyond DL5 may be considered as pazopanib levels were suboptimal as a result of drug interaction with dabrafenib.

Neonatal hyperlipidemia with pancreatitis: Novel gene mutation of lipoprotein lipase

Lipoprotein lipase (LPL) deficiency is an autosomal recessive metabolic disorder with varying presentation in infancy and childhood, whereas clinical manifestations are rare in neonatal period. The estimated prevalence is one in a million births. A 23-day-old baby was admitted with complaints of fever, vomiting, and lethargy. Blood sample drawn appeared lipemic. Lipemia retinalis was noted on funduscopic examination. Biochemical analysis revealed abnormal lipid profile with severe hypertriglyceridemia (10,300 mg/dL) and elevated serum lipase level (517 IU/L) indicative of LPL deficiency with acute pancreatitis. LPL deficiency was suspected and was confirmed by molecular genetic testing, which revealed a novel mutation in LPL gene. Dietary management and gemfibrozil were started following which serum triglyceride level decreased and serum lipase level normalized. The patient is following up regularly for growth and development monitoring.