Follow-up Recommendations for Completely Resected Gastroenteropancreatic Neuroendocrine Tumors

There is no consensus on optimal follow-up for completely resected gastroenteropancreatic neuroendocrine tumors. Published guidelines for follow-up are complex and emphasize closer surveillance in the first 3 years after resection. Neuroendocrine tumors have a different pattern and timescale of recurrence, and thus require more practical and tailored follow-up. The Commonwealth Neuroendocrine Tumour Collaboration convened an international multidisciplinary expert panel, in collaboration with the North American Neuroendocrine Tumor Society, to create patient-centered follow-up recommendations for completely resected gastroenteropancreatic neuroendocrine tumors. This panel used the RAND/UCLA (University of California, Los Angeles) Appropriateness Method to generate recommendations. A large international survey was conducted outlining current the surveillance practice of neuroendocrine tumor practitioners and shortcomings of the current guidelines. A systematic review of available data to date was supplemented by recurrence data from 2 large patient series. The resultant guidelines suggest follow-up for at least 10 years for fully resected small-bowel and pancreatic neuroendocrine tumors and also identify clinical situations in which no follow-up is required. These recommendations stratify follow-up strategies based on evidence-based prognostic factors that allow for a more individualized patient-centered approach to this complex and heterogeneous malignant neoplasm.

Long-Term Safety Experience with Telotristat Ethyl Across Five Clinical Studies in Patients with Carcinoid Syndrome

BACKGROUND

Patients with neuroendocrine tumors (NETs) and carcinoid syndrome experience considerable morbidity and mortality; carcinoid syndrome may be associated with shorter survival. Carcinoid syndrome is linked to tumoral secretion of serotonin and other bioactive substances. The subsequent debilitating diarrhea and urgency to defecate pose significant health risks. In previous studies, telotristat ethyl, a tryptophan hydroxylase inhibitor, was effective and well tolerated in treating carcinoid syndrome diarrhea. We present pooled safety data from five clinical trials with telotristat ethyl in patients with carcinoid syndrome.

SUBJECTS, MATERIALS, AND METHODS

Adverse events reported during telotristat ethyl treatment were pooled from two phase II and three phase III clinical trials in 239 patients with carcinoid syndrome. Long-term safety of telotristat ethyl and causes of hospitalization and death were reviewed; overall survival was estimated.

RESULTS

Mean (median; range) duration of exposure and follow-up was 1.3 years (1.1 years; 1 week to 5.7 years), with 309 total patient-years of exposure. Leading causes of hospitalization were gastrointestinal disorders or were related to the underlying tumor and related treatment. Survival estimates at 1, 2, and 3 years were 93%, 88%, and 77%. Nearly all deaths were due to progression or complication of the underlying disease; none were attributable to telotristat ethyl. There was one death in year 4.

CONCLUSION

Based on long-term safety data, telotristat ethyl is well tolerated and has a favorable long-term safety profile in patients with carcinoid syndrome.

IMPLICATIONS FOR PRACTICE

Carcinoid syndrome can cause persistent diarrhea, even in patients treated with somatostatin analogs. Across five clinical trials in patients with carcinoid syndrome, telotristat ethyl has been well tolerated and efficacious, providing clinicians with a new approach to help control carcinoid syndrome diarrhea, in addition to somatostatin analog therapy. By reducing the stool frequency in patients with carcinoid syndrome whose diarrhea is refractory to anticholinergics, such as loperamide and atropine/diphenoxylate, and somatostatin analog dose escalation, improvement in quality of life becomes an achievable goal.

Duration of Oxaliplatin-Containing Adjuvant Therapy for Stage III Colon Cancer: ASCO Clinical Practice Guideline

PURPOSE

To develop recommendations for duration of adjuvant chemotherapy with a fluoropyrimidine and oxaliplatin for patients with completely resected stage III colon cancer based on the results of trials of 3 months compared with 6 months of treatment.

METHODS

ASCO convened an Expert Panel and conducted a systematic review of relevant studies. The guideline recommendations were based on the review of evidence by the Expert Panel.

RESULTS

Pooled data from the six International Duration Evaluation of Adjuvant Chemotherapy (IDEA) Collaboration randomized controlled trials comprise the evidence base for these guideline recommendations.

RECOMMENDATIONS

The recommendations for therapy duration apply to patients with completely resected stage III colon cancer who are being offered adjuvant chemotherapy with oxaliplatin and a fluoropyrimidine. Recommendations are informed by the findings of a recent pooled analysis of clinical trials that compared 6 months versus 3 months of oxaliplatin-based chemotherapy. For patients at a high risk of recurrence (T4 and/or N2), adjuvant chemotherapy should be offered for a duration of 6 months. For patients at a low risk of recurrence (T1, T2, or T3 and N1), either 6 months of adjuvant chemotherapy or a shorter duration of 3 months may be offered on the basis of a potential reduction in adverse events and no significant difference in disease-free survival with the 3-month regimen. In determining duration of therapy, the Expert Panel recommends a shared decision-making approach, taking into account patient characteristics, values and preferences, and other factors and including a discussion of the potential for benefit and risks of harm associated with treatment duration. Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines .

Identification of high-risk human papillomavirus and Rb/E2F pathway genomic alterations in mutually exclusive subsets of colorectal neuroendocrine carcinoma

Colorectal neuroendocrine carcinomas, both small cell and large cell types, are highly aggressive tumors with poor prognosis compared with colorectal adenocarcinoma. The molecular drivers of neuroendocrine carcinoma are best defined in small cell lung cancer, which shows near-universal genomic alterations in TP53 and RB1. The genetics of colorectal neuroendocrine carcinoma remain poorly understood; recent studies demonstrated infrequent RB1 alterations and genetics closely resembling colorectal adenocarcinoma. To better define the molecular pathogenesis of colorectal neuroendocrine carcinoma, we performed capture-based next-generation sequencing on 25 cases and evaluated for expression of p53, Rb, p16, and high-risk human papillomavirus (HR-HPV) subtypes using immunohistochemistry, in situ hybridization, and polymerase chain reaction. Rb/E2F pathway dysregulation was identified in nearly all cases (23/25, 92%) and occurred via three distinct mechanisms. First, RB1 genomic alteration was present in 56% (14/25) of cases and was accompanied by Rb protein loss, high p16 expression, and absence of HR-HPV; these cases also had frequent genomic alterations in TP53, the PI3K/Ras and Wnt pathways, as well as in DNA repair genes, with 4/14 cases being hypermutated. Second, 16% (4/25) of cases, all left-sided, had TP53 alteration without RB1 alteration; half of these harbored high-level amplifications in CCNE1 and MYC or MYCN and arose in patients with ulcerative colitis. Finally, 28% (7/25) of cases, all rectal or anal, lacked genomic alterations in RB1 or TP53 but were positive for HR-HPV. Our data demonstrate that Rb/E2F pathway dysregulation is essential in the pathogenesis of colorectal neuroendocrine carcinoma, akin to neuroendocrine carcinomas in other anatomic sites. Moreover, colorectal neuroendocrine carcinomas stratify into three distinct molecular subgroups, which can be differentiated based on Rb protein and HR-HPV status. HR-HPV infection represents a distinct mechanism for Rb and p53 inactivation in cases lacking genomic alterations in either gene. Differential treatment strategies for hypermutated and HPV-driven cases could improve patient outcomes.

Emerging value of multigene panels for germline testing in patients with neuroendocrine tumors

226

Background: Neuroendocrine tumors (NETs) are known to be associated with hereditary syndromes stemming from MEN1, VHL, SDH or TSC mutations. Recent data suggest that additional germline mutations may be relevant, implying a role of germline testing with multigene panels. We examined genetic counseling (GC) referral and testing patterns, test results, and their changes over time in NET patients (pts). Methods: Retrospective chart review was conducted in 236 NET pts referred to UCSF Cancer Genetics and Prevention Program 2004-2017. Univariate logistic models were used to assess relationship between binary outcome and covariate. STATA was used for analysis and statistical significance was based on p < 0.05. Results: 139 referred pts (59%) followed up with GC. Pts with >1 family members diagnosed with cancer were more likely to attend GC [OR=2.75, p=0.010]. Among 107 pts tested, small bowel NETs were less associated with testing than pancreatic NETs [OR=0.15, p=0.001]. Single-gene tests were routine until 2015, when panels up to 130 genes became standard. Overall, 31 pts (29% of 107 tested) had a pathogenic/likely pathogenic (P/LP) result. There was no significant difference between single and multi-gene tests in identifying P/LP mutations (likely due to changes in threshold for testing over time), but greater diversity in P/LP mutations was noted with larger panels. Functional tumors showed lower rate of P/LP mutations than non-functional [OR=0.17, p=0.037]. Conclusions: Only 59% of referred pts followed up with GC, suggesting significant barriers to testing exist. Of those tested, 29% harbored a P/LP mutation. Germline mutations not traditionally associated with NETs were identified, highlighting the potential importance of larger panels to detect rare mutations. [Table: see text]

Understanding the Patient Experience with Carcinoid Syndrome: Exit Interviews from a Randomized, Placebo-controlled Study of Telotristat Ethyl

PURPOSE

Telotristat ethyl, an oral tryptophan hydroxylase inhibitor, is intended to treat carcinoid syndrome by reducing serotonin production. Telotristat ethyl was evaluated in TELESTAR, a Phase III study for patients who had carcinoid syndrome with at least 4 bowel movements (BMs) per day and who were receiving somatostatin analogue therapy. This interview substudy was conducted to provide insight into the patient experience in TELESTAR and to help understand whether reductions in BM frequency (the primary end point) and other symptoms were clinically meaningful.

METHODS

Participating sites were asked to invite (before randomization) all eligible patients to telephone interviews scheduled at the end of the double-blind treatment period. Patients and interviewers were blinded to treatment.

FINDINGS

All 35 interviewed participants reported diarrhea and/or excessive BMs at baseline. Patients reported that these symptoms negatively affected emotional, social, physical, and occupational well-being. Prespecified criteria for treatment response (achieving ≥30% reduction in BM frequency for at least 50% of the days) were met by 8 of 26 patients taking telotristat ethyl and 1 of 9 patients taking placebo. All 8 patients taking telotristat ethyl described clinically meaningful reductions in BM frequency and were very satisfied with the ability of the study drug to control their carcinoid syndrome symptoms. Overall, reports of being very satisfied were observed in 12 patients taking telotristat ethyl and 0 taking placebo.

IMPLICATIONS

Patient interviews revealed that TELESTAR patients, at baseline, were significantly affected by their high BM frequency. Patient reports of their clinical trial experience supported the significance of the primary end point and clinical responder analysis in TELESTAR, helping identify and understand clinically meaningful change produced by telotristat ethyl.

Evaluation of meaningful change in bowel movement frequency for patients with carcinoid syndrome

e15132

Background: Telotristat ethyl is a tryptophan hydroxylase inhibitor in development for the treatment of carcinoid syndrome (CS) in patients who receive somatostatin analog (SSA) therapy. In TELESTAR, a pivotal Phase 3 study, telotristat ethyl significantly reduced bowel movement (BM) frequency compared to placebo. The objective of this study was to psychometrically assess meaningful change in BM frequency using data collected within the TELESTAR study. Methods: An anchor-based approach consisted of mapping change from baseline in BM frequency to other patient reported assessments of change. These included the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core Questionnaire (EORTC QLQ-C30) Diarrhea Symptom responders, the EORTC GI.NET21 GI Symptom responders, and patient reported adequate relief at Week 12 (responders had a ≥ 10-point decrease in scores from Day 1 to Week 12). Parameters included within group mean change from baseline to Week 12, t-tests of the change (Wilcoxon Rank Sum for adequate relief), effect size (ES: calculated as the difference between mean on-treatment and baseline BM frequency, divided by the standard deviation of the baseline), and related confidence intervals. Results: There were 135 patients with CS, with a mean age of 63.6 years and mean baseline BM frequency of 5.7 BM/day. Anchor-based analyses indicated significant differences in BM frequency between adequate relief groups at Week 12 (ES: −1.58 vs. −0.79; p = 0.014), responders and non-responders on the EORTC QLQ-C30 Diarrhea Symptoms domain (ES: −1.24 vs. −0.59; p < 0.0001), and responders and non-responders on the EORTC GI.NET21 GI Symptoms Domain (ES: −1.49 vs. −0.75; p = 0.0053). These corresponded to BM frequency reductions of 1.7–1.9 BM/day, or ≥ 30%. Conclusions: Results of this study indicated that patients with CS experienced clinically meaningful reductions in BM frequency of ≥ 30% over the course of 12 weeks. Clinical trial information: NCT01677910.

Evaluation of meaningful change in bowel move frequency for patients with carcinoid syndrome

583

Background: Telotristat ethyl is a tryptophan hydroxylase inhibitor in development for the treatment of carcinoid syndrome (CS) in patients who receive somatostatin analog (SSA) therapy. In TELESTAR, a pivotal Phase 3 study, telotristat ethyl significantly reduced bowel movement (BM) frequency compared to placebo. Objective: The objective of this study was to psychometrically assess meaningful change in BM frequency using data collected within the TELESTAR study. Methods: An anchor-based approach consisted of mapping change from baseline in BM frequency to other patient reported assessments of change. These included the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core Questionnaire (EORTC QLQ-C30) Diarrhea Symptom responders, the EORTC GI.NET21 GI Symptom responders, and patient reported adequate relief at Week 12 (responders had a ≥ 10-point decrease in scores from Day 1 to Week 12). Parameters included within group mean change from baseline to Week 12, t-tests of the change (Wilcoxon Rank Sum for adequate relief), effect size (ES: calculated as the difference between mean on-treatment and baseline BM frequency, divided by the standard deviation of the baseline), and related confidence intervals. Results: There were 135 patients with CS, with a mean age of 63.6 years and mean baseline BM frequency of 5.7 BM/day. Anchor-based analyses indicated significant differences in BM frequency between adequate relief groups at Week 12 (ES: -1.58 vs. -0.79; p = 0.014), responders and non-responders on the EORTC QLQ-C30 Diarrhea Symptoms domain (ES: -1.24 vs. -0.59; p < 0.0001), and responders and non-responders on the EORTC GI.NET21 GI Symptoms Domain (ES: -1.49 vs. -0.75; p = 0.0053). These corresponded to BM frequency reductions of 1.7-1.9 BM/day, or ≥ 30%. Conclusions: Results of this study indicated that patients with CS experienced clinically meaningful reductions in BM frequency of ≥ 30% over the course of 12 weeks.

Telotristat Ethyl, a Tryptophan Hydroxylase Inhibitor for the Treatment of Carcinoid Syndrome

Purpose

Preliminary studies suggested that telotristat ethyl, a tryptophan hydroxylase inhibitor, reduces bowel movement (BM) frequency in patients with carcinoid syndrome. This placebo-controlled phase III study evaluated telotristat ethyl in this setting.

Patients and Methods

Patients (N = 135) experiencing four or more BMs per day despite stable-dose somatostatin analog therapy received (1:1:1) placebo, telotristat ethyl 250 mg, or telotristat ethyl 500 mg three times per day orally during a 12-week double-blind treatment period. The primary end point was change from baseline in BM frequency. In an open-label extension, 115 patients subsequently received telotristat ethyl 500 mg.

Results

Estimated differences in BM frequency per day versus placebo averaged over 12 weeks were –0.81 for telotristat ethyl 250 mg ( P < .001) and ‒0.69 for telotristat ethyl 500 mg ( P < .001). At week 12, mean BM frequency reductions per day for placebo, telotristat ethyl 250 mg, and telotristat ethyl 500 mg were –0.9, –1.7, and –2.1, respectively. Responses, predefined as a BM frequency reduction ≥ 30% from baseline for ≥ 50% of the double-blind treatment period, were observed in 20%, 44%, and 42% of patients given placebo, telotristat ethyl 250 mg, and telotristat ethyl 500 mg, respectively. Both telotristat ethyl dosages significantly reduced mean urinary 5-hydroxyindole acetic acid versus placebo at week 12 ( P < .001). Mild nausea and asymptomatic increases in gamma-glutamyl transferase were observed in some patients receiving telotristat ethyl. Follow-up of patients during the open-label extension revealed no new safety signals and suggested sustained BM responses to treatment.

Conclusion

Among patients with carcinoid syndrome not adequately controlled by somatostatin analogs, treatment with telotristat ethyl was generally safe and well tolerated and resulted in significant reductions in BM frequency and urinary 5-hydroxyindole acetic acid.

KRAS and Combined KRAS/TP53 Mutations in Locally Advanced Rectal Cancer are Independently Associated with Decreased Response to Neoadjuvant Therapy

BACKGROUND

The response of rectal cancers to neoadjuvant chemoradiation (CRT) is variable, but tools to predict response remain lacking. We evaluated whether KRAS and TP53 mutations are associated with pathologic complete response (pCR) and lymph node metastasis after adjusting for neoadjuvant regimen.

METHODS

Retrospective analysis of 229 pretreatment biopsies from patients with stage II/III rectal cancer was performed. All patients received CRT. Patients received 0-8 cycles of FOLFOX either before or after CRT, but prior to surgical excision. A subset was analyzed to assess concordance between mutation calls by Sanger Sequencing and a next-generation assay.

RESULTS

A total of 96 tumors (42 %) had KRAS mutation, 150 had TP53 mutation (66 %), and 59 (26 %) had both. Following neoadjuvant therapy, 59 patients (26 %) achieved pCR. Of 133 KRAS wild-type tumors, 45 (34 %) had pCR, compared with 14 of 96 (15 %) KRAS mutant tumors (p = .001). KRAS mutation remained independently associated with a lower pCR rate on multivariable analysis after adjusting for clinical stage, CRT-to-surgery interval and cycles of FOLFOX (OR 0.34; 95 % CI 0.17-0.66, p < .01). Of 29 patients with KRAS G12V or G13D, only 2 (7 %) achieved pCR. Tumors with both KRAS and TP53 mutation were associated with lymph node metastasis. The concordance between platforms was high for KRAS (40 of 43, 93 %).

CONCLUSIONS

KRAS mutation is independently associated with a lower pCR rate in locally advanced rectal cancer after adjusting for variations in neoadjuvant regimen. Genomic data can potentially be used to select patients for "watch and wait" strategies.

The spectrum of neuroendocrine tumors: histologic classification, unique features and areas of overlap

Neuroendocrine neoplasms are diverse in terms of sites of origin, functional status, and degrees of aggressiveness. This review will introduce some of the common features of neuroendocrine neoplasms and will explore the differences in pathology, classification, biology, and clinical management between tumors of different anatomic sites, specifically, the lung, pancreas, and prostate. Despite sharing neuroendocrine differentiation and histologic evidence of the neuroendocrine phenotype in most organs, well-differentiated neuroendocrine tumors (WD-NETs) and poorly differentiated neuroendocrine carcinomas (PD-NECs) are two very different families of neoplasms. WD-NETs (grade 1 and 2) are relatively indolent (with a natural history that can evolve over many years or decades), closely resemble non-neoplastic neuroendocrine cells, and demonstrate production of neurosecretory proteins, such as chromogranin A. They arise in the lungs and throughout the gastrointestinal tract and pancreas, but WD-NETs of the prostate gland are uncommon. Surgical resection is the mainstay of therapy, but treatment of unresectable disease depends on the site of origin. In contrast, PD-NECs (grade 3, small cell or large cell) of all sites often demonstrate alterations in P53 and Rb, exhibit an aggressive clinical course, and are treated with platinum-based chemotherapy. Only WD-NETs arise in patients with inherited neuroendocrine neoplasia syndromes (e.g., multiple endocrine neoplasia type 1), and some common genetic alterations are site-specific (e.g., TMPRSS2-ERG gene rearrangement in PD-NECs arising in the prostate gland). Advances in our understanding of the molecular basis of NETs should lead to new diagnostic and therapeutic strategies and is an area of active investigation.

First-in-Human Phase I Study of GSK2126458, an Oral Pan-Class I Phosphatidylinositol-3-Kinase Inhibitor, in Patients with Advanced Solid Tumor Malignancies

PURPOSE

GSK2126458 (GSK458) is a potent inhibitor of PI3K (α, β, γ, and δ), with preclinical studies demonstrating broad antitumor activity. We performed a first-in-human phase I study in patients with advanced solid tumors.

MATERIALS AND METHODS

Patients received oral GSK458 once or twice daily in a dose-escalation design to define the maximum tolerated dose (MTD). Expansion cohorts evaluated pharmacodynamics, pharmacokinetics, and clinical activity in histologically and molecularly defined cohorts.

RESULTS

One hundred and seventy patients received doses ranging from 0.1 to 3 mg once or twice daily. Dose-limiting toxicities (grade 3 diarrhea,n= 4; fatigue and rash,n= 1) occurred in 5 patients (n= 3 at 3 mg/day). The MTD was 2.5 mg/day (MTD with twice daily dosing undefined). The most common grade ≥3 treatment-related adverse events included diarrhea (8%) and skin rash (5%). Pharmacokinetic analyses demonstrated increased duration of drug exposure above target level with twice daily dosing. Fasting insulin and glucose levels increased with dose and exposure of GSK458. Durable objective responses (ORs) were observed across multiple tumor types (sarcoma, kidney, breast, endometrial, oropharyngeal, and bladder cancer). Responses were not associated withPIK3CAmutations (OR rate: 5% wild-type vs. 6% mutant).

CONCLUSIONS

Although the MTD of GSK458 was 2.5 mg once daily, twice-daily dosing may increase duration of target inhibition. Fasting insulin and glucose levels served as pharmacodynamic markers of drug exposure. Select patients achieved durable responses; however,PIK3CAmutations were neither necessary nor predictive of response. Combination treatment strategies and novel biomarkers may be needed to optimally target PI3K.

Neuroendocrine tumors, version 1.2015

Neuroendocrine tumors (NETs) comprise a broad family of tumors that may or may not be associated with symptoms attributable to hormonal hypersecretion. The NCCN Clinical Practice Guidelines in Oncology for Neuroendocrine Tumors discuss the diagnosis and management of both sporadic and hereditary NETs. This selection from the guidelines focuses on sporadic NETs of the pancreas, gastrointestinal tract, lung, and thymus.

A phase I dose-escalation study to assess safety, tolerability, pharmacokinetics, and preliminary efficacy of the dual mTORC1/mTORC2 kinase inhibitor CC-223 in patients with advanced solid tumors or multiple myeloma

BACKGROUND

The mammalian target of rapamycin (mTOR) pathway is essential for tumor development, yet mTOR inhibitors have yielded modest results. This phase 1 study investigated the mTORC1/mTORC2 inhibitor CC-223 in patients with advanced cancer.

METHODS

Patients with advanced solid tumors or multiple myeloma received an initial dose of 7.5-60 mg of CC-223, followed by oral daily dosing in 28-day cycles until disease progression. The primary objective was to determine the safety, tolerability, nontolerated dosage, maximum tolerated dosage (MTD), and preliminary pharmacokinetic profile. Secondary objectives were to evaluate pharmacodynamic effects and to describe preliminary efficacy.

RESULTS

Twenty-eight patients were enrolled and received ≥1 dose of CC-223. The most common treatment-related grade 3 adverse events were hyperglycemia, fatigue, and rash. Four patients had dose-limiting toxicities, including hyperglycemia, rash, fatigue, and mucositis. Therefore, 45 mg/d was determined to be the MTD. The pharmacokinetics of CC-223 demonstrated a mean terminal half-life ranging from 4.86 to 5.64 hours and maximum observed plasma concentration ranging from 269 to 480 ng/mL in patients who received CC-223 ≥45 mg/d. Phosphorylation of mTORC1/mTORC2 pathway biomarkers in blood cells was inhibited by CC-223 ≥30 mg/d with an exposure-response relationship. Best responses included 1 partial response (breast cancer; response duration 220 days; 30-mg/d cohort), stable disease (8 patients across ≥15 mg/d cohorts; response duration range, 36-168 days), and progressive disease (12 patients). The disease control rate was 32%.

CONCLUSIONS

CC-223 was tolerable, with manageable toxicities. Preliminary antitumor activity, including tumor regression, and evidence of mTORC1/mTORC2 pathway inhibition were observed.

Intratumoral myeloid cells regulate responsiveness and resistance to antiangiogenic therapy

Antiangiogenic therapy is commonly used in the clinic, but its beneficial effects are short-lived, leading to tumor relapse within months. Here, we found that the efficacy of angiogenic inhibitors targeting the VEGF/VEGFR pathway was dependent on induction of the angiostatic and immune-stimulatory chemokine CXCL14 in mouse models of pancreatic neuroendocrine and mammary tumors. In response, tumors reinitiated angiogenesis and immune suppression by activating PI3K signaling in all CD11b+ cells, rendering tumors nonresponsive to VEGF/VEGFR inhibition. Adaptive resistance was also associated with an increase in Gr1+CD11b+ cells, but targeting Gr1+ cells was not sufficient to further sensitize angiogenic blockade because tumor-associated macrophages (TAMs) would compensate for the lack of such cells and vice versa, leading to an oscillating pattern of distinct immune-cell populations. However, PI3K inhibition in CD11b+ myeloid cells generated an enduring angiostatic and immune-stimulatory environment in which antiangiogenic therapy remained efficient.

Telotristat etiprate, a novel serotonin synthesis inhibitor, in patients with carcinoid syndrome and diarrhea not adequately controlled by octreotide

Serotonin produced by neuroendocrine tumors is believed to be a principal cause of the diarrhea in carcinoid syndrome. We assessed the safety and efficacy of telotristat etiprate, an oral serotonin synthesis inhibitor, in patients with diarrhea associated with carcinoid syndrome. In this prospective, randomized study, patients with evidence of carcinoid tumor and ≥4 bowel movements (BMs)/day despite stable-dose octreotide LAR depot therapy were enrolled in sequential, escalating, cohorts of four patients per cohort. In each cohort, one patient was randomly assigned to placebo and three patients to telotristat etiprate, at 150, 250, 350, or 500 mg three times a day (tid). In a subsequent cohort, one patient was assigned to placebo and six patients to telotristat etiprate 500 mg tid. Patients were assessed for safety, BM frequency (daily diary), 24 h urinary 5-hydroxyindoleacetic acid (u5-HIAA), and adequate relief of carcinoid gastrointestinal symptoms (using a weekly questionnaire). Twenty-three patients were treated: 18 received telotristat etiprate and five received placebo. Adverse events were generally mild. Among evaluable telotristat etiprate-treated patients, 5/18 (28%) experienced a ≥30% reduction in BM frequency for ≥2 weeks, 9/16 (56%) experienced biochemical response (≥50% reduction or normalization in 24-h u5-HIAA) at week 2 or 4, and 10/18 (56%) reported adequate relief during at least 1 of the first 4 weeks of treatment. Similar activity was not observed in placebo-treated patients. Telotristat etiprate was well tolerated. Our observations suggest that telotristat etiprate has activity in controlling diarrhea associated with carcinoid syndrome. Further studies confirming these findings are warranted.

B cells regulate macrophage phenotype and response to chemotherapy in squamous carcinomas

B cells foster squamous cell carcinoma (SCC) development through deposition of immunoglobulin-containing immune complexes in premalignant tissue and Fcγ receptor-dependent activation of myeloid cells. Because human SCCs of the vulva and head and neck exhibited hallmarks of B cell infiltration, we examined B cell-deficient mice and found reduced support for SCC growth. Although ineffective as a single agent, treatment of mice bearing preexisting SCCs with B cell-depleting αCD20 monoclonal antibodies improved response to platinum- and Taxol-based chemotherapy. Improved chemoresponsiveness was dependent on altered chemokine expression by macrophages that promoted tumor infiltration of activated CD8(+) lymphocytes via CCR5-dependent mechanisms. These data reveal that B cells, and the downstream myeloid-based pathways they regulate, represent tractable targets for anticancer therapy in select tumors.