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<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

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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.