A next-generation BRAF inhibitor overcomes resistance to BRAF inhibition in patients with BRAF-mutant cancers using pharmacokinetics-informed dose escalation

RAF inhibitors have transformed treatment for BRAF V600-mutant cancer patients, but clinical benefit is limited by adaptive induction of ERK signaling, genetic alterations that induce BRAF V600 dimerization, and poor brain penetration. Next-generation pan-RAF dimer inhibitors are limited by narrow therapeutic index. PF-07799933 (ARRY-440) is a brain-penetrant, selective, pan-mutant BRAF inhibitor. PF-07799933 inhibited signaling in vitro, disrupted endogenous mutant-BRAF:wild-type-CRAF dimers, and spared wild-type ERK signaling. PF-07799933 ± binimetinib inhibited growth of mouse xenograft tumors driven by mutant BRAF that functions as dimers and by BRAF V600E with acquired resistance to current RAF inhibitors. We treated patients with treatment-refractory BRAF-mutant solid tumors in a first-in-human clinical trial (NCT05355701) that utilized a novel, flexible, pharmacokinetics-informed dose escalation design that allowed rapid achievement of PF-07799933 efficacious concentrations. PF-07799933 ± binimetinib was well-tolerated and resulted in multiple confirmed responses, systemically and in the brain, in BRAF-mutant cancer patients refractory to approved RAF inhibitors.

Individualised neoantigen therapy mRNA-4157 (V940) plus pembrolizumab versus pembrolizumab monotherapy in resected melanoma (KEYNOTE-942): a randomised, phase 2b study

BACKGROUND

Checkpoint inhibitors are standard adjuvant treatment for stage IIB-IV resected melanoma, but many patients recur. Our study aimed to evaluate whether mRNA-4157 (V940), a novel mRNA-based individualised neoantigen therapy, combined with pembrolizumab, improved recurrence-free survival and distant metastasis-free survival versus pembrolizumab monotherapy in resected high-risk melanoma.

METHODS

We did an open-label, randomised, phase 2b, adjuvant study of mRNA-4157 plus pembrolizumab versus pembrolizumab monotherapy in patients, enrolled from sites in the USA and Australia, with completely resected high-risk cutaneous melanoma. Patients with completely resected melanoma (stage IIIB-IV) were assigned 2:1 to receive open-label mRNA-4157 plus pembrolizumab or pembrolizumab monotherapy. mRNA-4157 was administered intramuscularly (maximum nine doses) and pembrolizumab intravenously (maximum 18 doses) in 3-week cycles. The primary endpoint was recurrence-free survival in the intention-to-treat population. This ongoing trial is registered at ClinicalTrials.gov, NCT03897881.

FINDINGS

From July 18, 2019, to Sept 30, 2021, 157 patients were assigned to mRNA-4157 plus pembrolizumab combination therapy (n=107) or pembrolizumab monotherapy (n=50); median follow-up was 23 months and 24 months, respectively. Recurrence-free survival was longer with combination versus monotherapy (hazard ratio [HR] for recurrence or death, 0·561 [95% CI 0·309-1·017]; two-sided p=0·053), with lower recurrence or death event rate (24 [22%] of 107 vs 20 [40%] of 50); 18-month recurrence-free survival was 79% (95% CI 69·0-85·6) versus 62% (46·9-74·3). Most treatment-related adverse events were grade 1-2. Grade ≥3 treatment-related adverse events occurred in 25% of patients in the combination group and 18% of patients in the monotherapy group, with no mRNA-4157-related grade 4-5 events. Immune-mediated adverse event frequency was similar for the combination (37 [36%]) and monotherapy (18 [36%]) groups.

INTERPRETATION

Adjuvant mRNA-4157 plus pembrolizumab prolonged recurrence-free survival versus pembrolizumab monotherapy in patients with resected high-risk melanoma and showed a manageable safety profile. These results provide evidence that an mRNA-based individualised neoantigen therapy might be beneficial in the adjuvant setting.

FUNDING

Moderna in collaboration with Merck Sharp & Dohme, a subsidiary of Merck & Co, Rahway, NJ, USA.

Nivolumab monotherapy or combination with ipilimumab with or without cobimetinib in previously treated patients with pancreatic adenocarcinoma (CheckMate 032)

BACKGROUND

Pancreatic cancer is one of the deadliest cancer types and represents a major unmet medical need. CheckMate 032 investigated safety and efficacy of nivolumab monotherapy and nivolumab plus ipilimumab with/without cobimetinib in advanced/metastatic solid tumors, including pancreatic cancer.

METHODS

In the original pancreatic cancer cohort, previously treated patients (≥1 prior regimen) with advanced/metastatic pancreatic adenocarcinoma were assigned to nivolumab 3 mg/kg every 2 weeks (monotherapy arm) or nivolumab 1 mg/kg and ipilimumab 1 mg/kg or 3 mg/kg every 3 weeks for four doses, followed by nivolumab 3 mg/kg every 2 weeks (combination arm). A subsequent modified pancreatic cohort (one or two prior regimens) received nivolumab 3 mg/kg every 2 weeks, ipilimumab 1 mg/kg every 6 weeks, and cobimetinib 60 mg orally once daily for 21 days on and 7 days off (triplet arm). The primary endpoint was investigator-assessed objective response rate (ORR). Secondary endpoints were investigator-assessed progression-free survival (PFS), PFS rate, overall survival (OS), OS rate, safety, and tolerability. Additionally, ORR, PFS, and duration of response were assessed by blinded independent central review (BICR) in the triplet arm.

RESULTS

18 patients received nivolumab monotherapy, 21 received nivolumab plus ipilimumab, and 30 received nivolumab plus ipilimumab plus cobimetinib. In the triplet arm, partial responses were observed in two patients per investigator (ORR 6.7% (95% CI 0.8% to 22.1%)) and in three patients per BICR (ORR 10% (95% CI 2.1% to 26.5%)); no responses were observed in the other arms. Median (95% CI) PFS per investigator was 1.4 (1.3 to 2.0), 1.4 (1.2 to 2.7), and 3.0 (1.5 to 4.1) months for the monotherapy, nivolumab plus ipilimumab, and triplet arms, respectively. Median (95% CI) OS was 5.1 (2.0 to 9.0) months, 4.0 (1.9 to 5.6) months, and 6.2 (3.9 to 11.4) months, respectively. Most treatment-related adverse events were grade 2 or less.

CONCLUSIONS

Nivolumab with or without ipilimumab did not elicit objective responses in previously treated patients with advanced pancreatic adenocarcinoma, although three confirmed partial responses and manageable safety were observed with cobimetinib-containing triplet therapy. The small sample size and differences in baseline disease-specific characteristics between arms limit interpretation of these results.

Evaluation of potential biomarkers for lenvatinib plus pembrolizumab among patients with advanced endometrial cancer: results from Study 111/KEYNOTE-146

BACKGROUND

Lenvatinib plus pembrolizumab demonstrated clinically meaningful benefit in patients with previously treated advanced endometrial carcinoma in Study 111/KEYNOTE-146 (NCT02501096). In these exploratory analyses from this study, we evaluated the associations between clinical outcomes and gene expression signature scores and descriptively summarized response in biomarker subpopulations defined by tumor mutational burden (TMB) and DNA variants for individual genes of interest.

METHODS

Patients with histologically confirmed metastatic endometrial carcinoma received oral lenvatinib 20 mg once daily plus intravenous pembrolizumab 200 mg every 3 weeks for 35 cycles. Archived formalin-fixed paraffin-embedded tissue was obtained from all patients. T-cell-inflamed gene expression profile (TcellinfGEP) and 11 other gene signatures were evaluated by RNA sequencing. TMB, hotspot mutations in PIK3CA (oncogene), and deleterious mutations in PTEN and TP53 (tumor suppressor genes) were evaluated by whole-exome sequencing (WES).

RESULTS

93 and 79 patients were included in the RNA-sequencing-evaluable and WES-evaluable populations, respectively. No statistically significant associations were observed between any of the RNA-sequencing signature scores and objective response rate or progression-free survival. Area under the receiver operating characteristic curve values for response ranged from 0.39 to 0.54; all 95% CIs included 0.50. Responses were seen regardless of TMB (≥175 or <175 mutations/exome) and mutation status. There were no correlations between TcellinfGEP and TMB, TcellinfGEP and microvessel density (MVD), or MVD and TMB.

CONCLUSIONS

This analysis demonstrated efficacy for lenvatinib plus pembrolizumab regardless of biomarker status. Results from this study do not support clinical utility of the evaluated biomarkers. Further investigation of biomarkers for this regimen is warranted.

TRIAL REGISTRATION NUMBER

NCT02501096.

Pralsetinib in Patients with Advanced/Metastatic Rearranged During Transfection (RET)-Altered Thyroid Cancer: Updated Efficacy and Safety Data from the ARROW Study

Background: Rearranged during transfection (RET) alterations are targetable oncogenic drivers in thyroid cancer. Primary data from the open-label, phase 1/2 ARROW study demonstrated clinical activity and manageable safety with pralsetinib, a selective RET inhibitor, in patients with advanced/metastatic RET-altered thyroid cancer. We present an updated analysis with more patients and longer follow-up. Methods: Adult patients with advanced/metastatic RET-mutant medullary thyroid cancer (MTC) or RET fusion-positive thyroid cancer who initiated oral pralsetinib at 400 mg once daily were included. Primary endpoints were overall response rate (ORR) by blinded independent central review (per RECIST v1.1) and safety. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), and overall survival. Responses were assessed in three cohorts of patients with baseline measurable disease: patients with RET-mutant MTC who had received prior cabozantinib and/or vandetanib (C/V), treatment-naïve patients with RET-mutant MTC, and patients with previously treated RET fusion-positive thyroid cancer. Patient-reported outcomes (PROs) were an exploratory endpoint. Results: As of October 18, 2021, the measurable disease population comprised of 61 patients with RET-mutant MTC and prior C/V, 62 treatment-naïve patients with RET-mutant MTC, and 22 patients with RET fusion-positive thyroid cancer who had received prior systemic therapy, including radioactive iodine. The ORR was 55.7% [confidence interval; 95% CI: 42.4-68.5] in patients with RET-mutant MTC and prior C/V, 77.4% [95% CI: 65.0-87.1] in treatment-naïve patients with RET-mutant MTC, and 90.9% [95% CI: 70.8-98.9] in patients with previously treated RET fusion-positive thyroid cancer. Median DoR and median PFS were both 25.8 months in patients with RET-mutant MTC and prior C/V, not reached in treatment-naïve patients with RET-mutant MTC, and 23.6 and 25.4 months, respectively, in patients with previously treated RET fusion-positive thyroid cancer. In the RET-altered thyroid cancer safety population (N = 175), 97.1% of patients reported a treatment-related adverse event (TRAE); these led to discontinuation in 5.7% and dose reduction in 52.6% of patients. There was one death (0.6%) due to a TRAE. PROs improved or remained stable after pralsetinib treatment. Conclusions: In this updated analysis of the ARROW study, pralsetinib continued to show deep and durable clinical activity and a manageable safety profile in patients with advanced/metastatic RET-altered thyroid cancer. Clinical Trial Registration: NCT03037385.

Characteristics and Survival Outcomes of Patients With Metastatic RET Fusion-Positive Solid Tumors Receiving Non-RET Inhibitor Standards of Care in a Real-World Setting

PURPOSE

RET fusions are oncogenic drivers across different solid tumors. However, the genomic landscape and natural history of patients with RET fusion-positive solid tumors are not well known. We describe the clinical characteristics of RET tyrosine kinase inhibitor (TKI)-naïve patients with RET fusion-positive solid tumors (excluding non-small-cell lung cancer [NSCLC]), treated in a real-world setting and assess the prognostic effect of RET fusions.

METHODS

Data for RET TKI-naïve patients with metastatic solid tumors (excluding NSCLC) who had ≥one Foundation Medicine comprehensive genomic profiling test (January 1, 2011-March 31, 2022) were obtained from a deidentified nationwide (US-based) clinicogenomic database. The primary objective of this study was to compare the overall survival (OS) of patients with RET fusion-positive tumors versus matched patients with RET wild-type (RET-WT) tumors. Patients with RET-WT solid tumors were matched (4:1) to patients with RET fusion-positive tumors on the basis of preselected covariates.

RESULTS

The study population included 26 patients in the RET fusion-positive cohort, 7,220 patients in the RET-WT cohort (before matching), and 104 patients in the matched RET-WT cohort. Co-occurring genomic alterations were rare in the RET fusion-positive cohort. Median OS was consistently lower in patients with RET fusion-positive tumors versus those with RET-WT tumors, using three different analyses (hazard ratios, 2.0, 1.7, and 2.2).

CONCLUSION

These data suggest that RET fusions represent a negative prognostic factor in patients with metastatic solid tumors and highlight the need for wider genomic testing and use of RET-specific TKIs that could improve patient outcomes. Our study also highlights the value of real-world data when studying rare cancers or cancers with rare genomic alterations.

A Phase Ib/II Study of Lenvatinib and Pembrolizumab in Advanced Endometrial Carcinoma (Study 111/KEYNOTE-146): Long-Term Efficacy and Safety Update

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The open-label phase Ib/II Study 111/KEYNOTE-146 of daily lenvatinib 20 mg plus pembrolizumab 200 mg once every 3 weeks showed promising efficacy and tolerable safety in patients with previously treated advanced endometrial carcinoma (EC; primary data cutoff date: January 10, 2019). This updated analysis reports long-term follow-up efficacy and safety data from 108 patients with previously treated EC included in the primary analysis. End points included objective response rate, duration of response, progression-free survival, overall survival, and safety. Investigators performed tumor assessments per immune-related RECIST. At the updated data cutoff date (August 18, 2020), the median study follow-up duration was 34.7 months (95% CI, 30.9 to 41.2), the objective response rate was 39.8% (95% CI, 30.5 to 49.7), and the median duration of response was 22.9 months (95% CI, 10.2 to not estimable). The median progression-free survival and overall survival were 7.4 months (95% CI, 5.2 to 8.7) and 17.7 months (95% CI, 15.5 to 25.8), respectively. Treatment-related treatment-emergent adverse events of any grade occurred in 104 (96.3%) patients. The most common grade ≥ 3 treatment-related treatment-emergent adverse events were hypertension (33.3%), elevated lipase (9.3%), fatigue (8.3%), and diarrhea (7.4%). The results demonstrate extended efficacy and tolerability of lenvatinib plus pembrolizumab in this cohort of patients with previously treated advanced EC.

Health-related quality-of-life analyses from a multicenter, randomized, double-blind phase 2 study of patients with differentiated thyroid cancer treated with lenvatinib 18 or 24 mg/day

BACKGROUND

In the phase 2 double-blind Study 211, a starting dose of lenvatinib 18 mg/day was compared with the approved starting dose of 24 mg/day in patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC). Predefined criteria for noninferiority for efficacy in the 18 mg arm were not met; safety was similar in both arms. Impact of lenvatinib treatment on health-related quality-of-life (HRQoL) was a secondary endpoint of Study 211.

METHODS

Patients with RR-DTC were randomly assigned to a blinded starting dose of lenvatinib 18 mg/day or 24 mg/day. HRQoL was assessed at baseline, every 8 weeks until Week 24, then every 16 weeks, and at the off-treatment visit, using the EQ-5D-3L and FACT-G instruments. Completion and compliance rates, mean change from baseline, and times to first and definitive deterioration were evaluated.

RESULTS

Baseline EQ-5D and FACT-G scores, and overall changes from baseline, were comparable between patients in the lenvatinib 18 mg/day (n = 77) and 24 mg/day arms (n = 75). For the 18 mg versus 24 mg arms, least squares mean differences were -0.42 (95% CI -4.88, 4.03) for EQ-5D-VAS and 0.47 (95% CI -3.45, 4.39) for FACT-G total. Time to first deterioration did not significantly favor either arm; EQ-5D-VAS HR [18 mg/24 mg] 0.93 (95% CI 0.61-1.40), EQ-5D-HUI HR [18 mg/24 mg] 0.68 (95% CI 0.44-1.05), FACT-G total HR [18 mg/24 mg] 0.73 (95% CI 0.48-1.12). Time to definitive deterioration did not significantly favor either arm, though EQ-5D-VAS showed a trend in favor of the 24 mg arm (HR [18 mg/24 mg] 1.72; 95% CI 0.99-3.01); EQ-5D-HUI HR [18 mg/24 mg] was 0.96 (95% CI 0.57-1.63), FACT-G total HR [18 mg/24 mg] was 0.72 (95% CI 0.43-1.21).

CONCLUSIONS

In Study 211, HRQoL for patients in the lenvatinib 18 mg/day arm was not statistically different from that of patients in the 24 mg/day arm. These data further support the use of the approved lenvatinib starting dose of 24 mg/day in patients with RR-DTC.

CLINICALTRIALS

GOV NUMBER

NCT02702388.

A Rare Case of Demodicosis Following Treatment With Oral Fluconazole

Demodex folliculorum and Demodex brevis are commensal human ectoparasites that reside within or near hair follicles and have been highly associated with rosacea-like papulopustular skin eruptions. We present an interesting case of recurrent, iatrogenic demodicosis in a 56-year-old man. We suspect this to have been triggered by antifungal therapy given it occurred twice closely following azole treatment. We propose that oral antifungals in the setting of immunosuppression can alter the skin microbiome, facilitating Demodex proliferation.

Epacadostat Plus Pembrolizumab and Chemotherapy for Advanced Solid Tumors: Results from the Phase I/II ECHO-207/KEYNOTE-723 Study

BACKGROUND

Epacadostat, an oral, selective inhibitor of IDO1, has shown activity when administered with pembrolizumab. We evaluated the addition of chemotherapy to epacadostat and pembrolizumab in patients with advanced or metastatic solid tumors. One proposed mechanism of resistance to PD-1 checkpoint inhibition is through immunosuppression mediated by L-kynurenine. IDO1, indoleamine-2,3-dioxygenase 1 is the rate-limiting enzyme catalyzing the conversion of L-tryptophan to L-kynurenine. If IDO1 is a mechanism of tumor escape from checkpoint inhibition, then addition of an IDO1 inhibitor with a PD-1 checkpoint inhibitor could enable tumor response to immunotherapy.

METHODS

Patients received one of 7 tumor-appropriate chemotherapy regimens. Pembrolizumab 200 mg was infused intravenously every 3 weeks. Epacadostat 100 mg was administered orally twice daily. The primary objectives of phase I were determining safety/tolerability and defining the maximum tolerated or pharmacologically active dose of epacadostat. Phase II of the study was designed to enroll efficacy-expansion cohorts and to assess changes in the tumor and tumor microenvironment via mandatory-biopsy cohorts.

RESULTS

A total of 70 patients were enrolled. Twelve patients were enrolled in the phase II mandatory-biopsy cohorts. Due to early study closure, efficacy expansion did not enroll. Grades 3 and 4 treatment-emergent adverse events (TEAEs) occurred in 78.6% of patients. Neutropenia and disease progression were the only grades 3 and 4 TEAEs reported in ≥10.0% of patients. One treatment-related death was reported. The ORR was 31.4% across all treatment groups.

CONCLUSION

The combination of epacadostat 100 mg bid with pembrolizumab and chemotherapy had an acceptable safety profile. This regimen showed antitumor activity across multiple types of advanced or metastatic solid tumors (ClinicalTrials.gov Identifier: NCT03085914).

Abstract CT502: Preliminary immunological monitoring of first-in-human immunotherapy-trio for advanced head and neck squamous cell carcinoma

Background: Preclinical studies document that complex cancer vaccines, combined with T cell agonists and anti-PD-1, can augment therapeutic efficacy. Here we report preliminary immunological analyses of patients enrolled in a first-in-human immunotherapy-trio study of multivalent autophagosome vaccine (DPV-001), with sequenced checkpoint inhibition (anti-PD-1; retifanlimab), with/without anti-GITR agonist (INCAGN-1949), in recurrent or metastatic HNSCC (NCT04470024).

Methods: Peripheral blood (PB) and sera are collected regularly and PB are evaluated by flow cytometry. Biopsies obtained at baseline, D15 and D45 are analyzed by multiplex IF and 10x Genomics scRNA-Seq. Sera are being analyzed by phage immunoprecipitation (PhIP) sequencing for reactivity against the human proteome.

Results: Preliminary results document increases in activated CD4 and CD8 effector memory T cells (TEM) with vaccine alone. Changes in tumor microenvironment (TEM) were also observed with increased infiltration of immune cells. Evaluation of changes to humoral immunity, T cell function and TCR analyses are ongoing.

Conclusions: We previously reported immunological monitoring of a phase I/II trial of an autophagosome cancer vaccine (DPV-001) containing more than 300 shared cancer antigens, as adjuvant therapy for NSCLC. Vaccination induced or augmented immune responses to more than 50 cancer antigens shared with head and neck squamous cell carcinoma (HNSCC). Preclinical studies combining this cancer vaccine with αGITR agonist and αPD-1 augmented therapeutic efficacy [PMID: 31747946], and provided the rationale for the current study. This is the first clinical trial to perform such a study with αGITR agonist (INCAGN-1949), in humans.

Support: Incyte, Providence Medical Foundation, The Harder Family, Nancy Lematta.

Citation Format: Rom S. Leidner, Matthew H. Taylor, Tarsem L. Moudgil, Tanisha L. Christie, Yoshinobu Koguchi, Alexa Dowdell, William L. Redmond, Shawn M. Jensen, Carmen Ballesteros-Merino, Jake A. Vancampen, Venkatesh Rajamanickam, Brady M. Bernard, Christopher Paustian, Traci L. Hilton, Hong-Ming Hu, Richard B. Bell, Walter J. Urba, Carlo B. Bifulco, Brian Piening, Bernard A. Fox. Preliminary immunological monitoring of first-in-human immunotherapy-trio for advanced head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT502.

innovaTV 207: New combination dosing cohorts in the open label phase 2 study of tisotumab vedotin in solid tumors

TPS6100

Background: Tisotumab vedotin (TV; TIVDAK) is a tissue factor (TF)-directed antibody-drug conjugate that has been granted accelerated approval in the US for treatment of adults with recurrent/metastatic (r/m) cervical cancer with disease progression on or after chemotherapy. TV remains investigational in other tumor types including squamous cell carcinoma of the head and neck (HNSCC) and squamous non-small cell lung cancer (sqNSCLC). This abstract presents the addition of Part D to innovaTV 207 (NCT03485209), a global, open label, multicenter phase 2 trial investigating the safety, tolerability, and activity of TV in solid tumors. Untreated patients (pts) with r/m HNSCC or sqNSCLC enrolled in Part D will receive either TV in combination with pembrolizumab (pembro) or TV + pembro and a platinum agent. Based on encouraging preliminary safety and efficacy results with 2.0 mg/kg TV once every 3 weeks (Q3W) in combination with pembro or carboplatin (carbo) in innovaTV 205 cervical cancer study cohorts, TV is being evaluated at 2.0 mg/kg Q3W in combination with pembro or pembro + carbo (or cisplatin). Methods: Up to 140 treatment-naive pts with r/m HNSCC or sqNSCLC will be enrolled in Part D of innovaTV 207. First, the All-Comers cohorts for HNSCC and sqNSCLC will each enroll up to 30 pts, regardless of PD-L1 expression, for Q3W dosing with 2.0 mg/kg TV in combination with 200 mg pembro and AUC 5 carbo. After enrollment in the HNSCC All-Comers Cohort is complete, up to 20 pts with HNSCC will be enrolled into a Cisplatin Safety Cohort for dosing with 2.0 mg/kg TV in combination with 200 mg pembro and 100 mg/m2 cisplatin. Completion of enrollment in the All-Comers Cohort for each tumor type will also be followed by enrollment of up to 30 pts with HNSCC (CPS ≥1) and 30 pts with sqNSCLC (TPS ≥1%) into PD-L1 Selected cohorts for dosing with TV in combination with 200 mg pembro. Response will be assessed every 6 weeks for the first 6 months, every 12 weeks for the next 6 months, and then every 6 months after that. Pts with HNSCC must have had no previous systemic therapy for metastatic disease (exception is systemic therapy given as part of multimodal treatment for locally advanced disease completed > 6 months prior). Pts with NSCLC must have histologically or cytologically documented squamous cell NSCLC and must not have had any previous systemic therapy for metastatic disease or radiation therapy to the lung that is > 30 Gy within 6 months of the first dose of study drug. The primary endpoint is investigator-determined confirmed ORR per RECIST v1.1. Secondary endpoints include confirmed and unconfirmed ORR per RECIST v1.1, disease control rate, duration of response, time to response, PFS, OS, safety and tolerability, pharmacokinetics, and immunogenicity. The trial opened in June 2018 and was amended to add Part D in November 2021. Part D enrollment will begin in early 2022; updates will be provided at the meeting. Clinical trial information: NCT03485209.

Pralsetinib in patients (pts) with advanced or metastatic RET-altered thyroid cancer (TC): Updated data from the ARROW trial

6080

Background: Alterations in RET are targetable oncogenic drivers in TC. Pralsetinib is a highly potent, selective RET inhibitor, with demonstrated efficacy in pts with RET-altered TC. In a previous analysis of the Phase I/II ARROW trial (NCT03037385; data cutoff: 22 May 2020), overall response rates [ORR; measurable-disease population] with pralsetinib at 400 mg once daily (QD) were 60% (33/55) and 71% (15/21) in pts with RET-mutant medullary TC ( RET-mutant MTC) who had received prior multikinase inhibitors cabozantinib and/or vandetanib (C/V), and those who were treatment naïve, respectively, and 89% (8/9) in pts with previously treated RET fusion-positive TC ( RET-fp TC). Here we report an updated analysis of these cohorts in the intention-to-treat (ITT) population. Methods: Adult pts with RET-altered locally advanced/metastatic TC who had enrolled in ARROW and initiated pralsetinib at 400 mg QD, were included. Phase II primary endpoints: ORR (by blinded independent central review, per RECIST v1.1) and safety. Efficacy endpoints for this analysis were assessed in the ITT population. Safety was assessed in all pts with RET-altered TC who initiated pralsetinib at 400 mg QD. Enrolment cutoff: 23 August 2020 for the ITT population; data cutoff: 12 April 2021. Results: The ITT population comprised 145 pts with RET-mutant MTC (with or without prior systemic therapy, including C/V) and 22 pts with RET-fp TC, 21 of whom had received prior systemic therapy (including multikinase inhibitor[s] and/or radioactive iodine). In pts with RET-mutant MTC who had received prior C/V (n = 67), ORR was 51% (34/67; 95% CI 38–63; 2 complete responses [CR]; 32 partial responses [PR]), median duration of response (DoR) was 25.8 months (95% CI 18.0–not reached [NR]) and median progression-free survival (PFS) was 24.9 months (95% CI 19.7–31.2). In treatment-naïve pts with RET-mutant MTC, ORR was 72% (48/67; 95% CI 59–82; 4 CR; 44 PR), and median DoR and median PFS were not reached. In pts with previously treated RET-fp TC, ORR was 86% (18/21; 95% CI 64–97; 3 CR; 15 PR), median DoR was 17.5 months (95% CI 16.0–NR) and median PFS was 19.4 months (95% CI 13.0–NR). Median overall survival (OS) was not reached in any of the cohorts. The safety population comprised 172 pts with RET-altered TC treated at 400 mg QD. The most common treatment-related adverse events (TRAEs) were increased aspartate aminotransferase (n = 67; 39%), anemia (n = 60; 35%), hypertension (n = 57; 33%) and decreased white blood cell count (n = 52; 30%). Serious TRAEs were reported in 27 pts (16%); the most frequent was pneumonitis (n = 5; 3%). Nine pts (5%) discontinued pralsetinib due to a TRAE and one patient ( < 1%) died due to a TRAE ( pneumocystis jirovecii pneumonia) following 44 days ( < 3 cycles) on pralsetinib. Conclusions: In this updated analysis including more pts, pralsetinib continues to be efficacious with a manageable safety profile in pts with RET-altered TC. Clinical trial information: NCT03037385.

Recommended phase 2 dose (RP2D) of HB-200 arenavirus-based cancer immunotherapies in patients with HPV16+ cancers

2517

Background: Treatment options are limited for patients with recurrent or metastatic human papillomavirus 16 positive (HPV16+) cancers. Generation and maintenance of HPV16+ cancers requires stable expression of HPV16-specific E7 and E6 oncoproteins, which are also a source of tumor-specific immunogenic neoantigens. HB-201 and HB-202 are replicating live-attenuated vectors based on lymphocytic choriomeningitis virus and Pichinde virus, respectively, which express the same non-oncogenic HPV16 E7E6 fusion protein and infect antigen presenting cells to induce tumor-specific T cell responses. The Phase 1 part of this study of HB-200 therapy (HB-201 single-vector therapy and HB-202/HB-201 two-vector alternating therapy) was conducted to determine RP2D for further exploration alone or in combination with pembrolizumab. Methods: The Phase 1 part used a 3+3 dose escalation design with up to 3 dose levels (DLs) of HB-201 and 4 DLs of HB-202/HB-201 explored. Patients with HPV16+ head and neck squamous cell carcinoma (HNSCC) or with other HPV16+ cancers were evaluated. Safety, tolerability, immunogenicity, and preliminary antitumor activity by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 or immune RECIST were assessed to determine RP2D. Results: As of January 2022, 65 patients with a median of 3 prior anticancer treatments have been enrolled in the Phase 1 part of the study. All had HPV16+ confirmed genotype; the most common primary site was oropharynx, followed by anal and cervix. Adverse events were generally mild or moderate. For HB-201, 3 DLs, 2 dosing schedules and 2 administration routes were assessed across 40 patients. At DL3 of HB-201 administered intravenously (IV), dose-limiting toxicity (DLT) occurred in 1/6 patients in the HNSCC group (Grade 4 encephalopathy, fully recovered) and 1/2 patients in the non-HNSCC group (Grade 3 rash, fully recovered). Preliminary safety, efficacy, and immunogenicity data support IV injection of DL3 (5 × 107 units) every 3 weeks (Q3W) as the RP2D for HB-201 single-vector therapy. For HB-202/HB-201, 4 DLs and 2 administration routes were assessed across 25 patients. At DL4 of HB-202/HB-201 IV, 1/5 subjects in the HNSCC group reported a DLT (Grade 4 hepatitis, recovering at time of discontinuation). RP2D for HB-202/HB-201 will be determined in the very near future. Tumor control, including partial response, have been observed in subjects treated with either HB-201 or HB-202/HB-201 as monotherapy. Conclusions: HB-201 and HB-202/HB-201 were generally well tolerated and showed preliminary antitumor activity in heavily pre-treated patients with HPV16+ solid tumors. DL3 was selected as RP2D for HB-201 monotherapy. In the Phase 2 part of the study a combination of HB-201 at 5 × 106 units IV Q3W with pembrolizumab is being tested in HPV16+ HNSCC patients. Clinical trial information: NCT04180215.

Lenvatinib dose, efficacy, and safety in the treatment of multiple malignancies

INTRODUCTION

Lenvatinib is an oral multitargeted tyrosine kinase inhibitor that has shown efficacy and manageable safety across multiple cancer types. The recommended starting doses for lenvatinib differ across cancer types and indications based on whether it is used as monotherapy or as combination therapy.

AREAS COVERED

This review covers clinical trials that established the dosing paradigm and efficacy of lenvatinib and defined its adverse-event profile as a monotherapy; or in combination with the mTOR inhibitor, everolimus; or the anti-PD-1 antibody, pembrolizumab; and/or chemotherapy.

EXPERT OPINION

Lenvatinib has been established as standard-of-care either as a monotherapy or in combination with other anticancer agents for the treatment of radioiodine-refractory differentiated thyroid carcinoma, hepatocellular carcinoma, renal cell carcinoma, and endometrial carcinoma, and is being investigated further across several other tumor types. The dosing and adverse-event management strategies for lenvatinib have been developed through extensive clinical trial experience. Collectively, the data provide the rationale to start lenvatinib at the recommended doses and then interrupt or dose reduce as necessary to achieve required dose intensity for maximized patient benefit. The adverse-event profile of lenvatinib is consistent with that of other tyrosine kinase inhibitors, and clinicians are encouraged to review and adopt relevant symptom-management strategies.

Safety and Efficacy of Pembrolizumab in Combination with Acalabrutinib in Advanced Head and Neck Squamous Cell Carcinoma: Phase 2 Proof-of-Concept Study

PURPOSE

Programmed cell death-1 (PD-1) receptor inhibitors have shown efficacy in head and neck squamous cell carcinoma (HNSCC), but treatment failure or secondary resistance occurs in most patients. In preclinical murine carcinoma models, inhibition of Bruton's tyrosine kinase (BTK) induces myeloid cell reprogramming that subsequently bolsters CD8+ T cell responses, resulting in enhanced antitumor activity. This phase 2, multicenter, open-label, randomized study evaluated pembrolizumab (anti-PD-1 monoclonal antibody) plus acalabrutinib (BTK inhibitor) in recurrent or metastatic HNSCC.

PATIENTS AND METHODS

Patients received pembrolizumab 200 mg intravenously every 3 weeks, alone or in combination with acalabrutinib 100 mg orally twice daily. Safety and overall response rate (ORR) were co-primary objectives. The secondary objectives were progression-free survival (PFS) and overall survival.

RESULTS

Seventy-six patients were evaluated (pembrolizumab, n = 39; pembrolizumab + acalabrutinib, n = 37). Higher frequencies of grade 3-4 treatment-emergent adverse events (AE; 65% vs. 39%) and serious AEs (68% vs. 31%) were observed with combination therapy versus monotherapy. ORR was 18% with monotherapy versus 14% with combination therapy. Median PFS was 2.7 [95% confidence interval (CI), 1.4-6.8] months in the combination arm and 1.7 (95% CI, 1.4-4.0) months in the monotherapy arm. The study was terminated due to lack of clinical benefit with combination treatment. To assess how tumor immune contexture was affected by therapy in patients with pre- and post-treatment biopsies, spatial proteomic analyses were conducted that revealed a trend toward increased CD45+ leukocyte infiltration of tumors from baseline at day 43 with pembrolizumab (monotherapy, n = 5; combination, n = 2), which appeared to be higher in combination-treated patients; however, definitive conclusions could not be drawn due to limited sample size.

CONCLUSIONS

Despite lack of clinical efficacy, immune subset analyses suggest that there are additive effects of this combination; however, the associated toxicity limits the feasibility of combination treatment with pembrolizumab and acalabrutinib in patients with recurrent or metastatic HNSCC.

Association between biomarkers and clinical outcomes of lenvatinib + pembrolizumab in advanced renal cell carcinoma (RCC): Results from Study 111/KEYNOTE-146

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Background: In the Study 111/KEYNOTE-146 trial (NCT02501096; N=147), lenvatinib (lenva) + pembrolizumab (pembro) showed encouraging antitumor activity and a manageable safety profile in treatment-naive (n=23) or previously treated metastatic RCC (n=105, previously treated with immune checkpoint inhibitor [ICI]; n=19, previously treated ICI naive); 145 had clear cell RCC and 2 had non-clear cell RCC. In this exploratory analysis, we evaluated the association between clinical outcomes and gene expression signatures and DNA variants for individual RCC-specific driver genes of interest based on published reports. Methods: Patients (pts) with metastatic RCC were treated with lenva 20 mg orally once daily + pembro 200 mg intravenously once every 3 weeks. The analysis population included pts with treatment-naive (n=10) and ICI pretreated (n=70) disease with evaluable RNA-sequencing data for the 18-gene T-cell–inflamed gene expression profile (TcellinfGEP) and for 11 other signatures (angiogenesis; glycolysis; gMDSC; hypoxia; mMDSC; MVD; MYC; proliferation; RAS; stroma/EMT/TGFβ; WNT) and whole exome sequencing (WES) data for DNA variants for individual genes ( VHL, PBRM1, BAP1, and SETD2). Specimens were collected prior to the start of treatment. The associations between each signature score and ORR and PFS per immune-related RECIST were evaluated using logistic regression and Cox proportional hazards, respectively. One-sided P values for TcellinfGEP (hypothesized positive association) and two-sided P values for all other signatures (no hypothesized association) were adjusted for multiplicity using the Hochberg step-up procedure; significance was prespecified at α=0.05. The association between DNA variants for individual genes and ORR was evaluated descriptively. Clinical data cutoff was August 18, 2020. Results: Of 147 treated pts, RNA sequencing and WES data were available for 80 (54%) and 60 (41%), respectively. TcellinfGEP was not associated with ORR ( P=0.827) or PFS ( P=0.741), nor were the other 11 signatures before or after adjustment for TcellinfGEP. ORR for DNA variants reported in the table. Conclusions: In this exploratory analysis of pts with metastatic RCC enrolled in Study 111/KEYNOTE-146 treated with lenva + pembro, responses were observed regardless of biomarker status. There were no statistically significant associations between gene signatures and clinical outcomes. Clinical benefit was observed regardless of VHL, PBRM1, BAP1, or SETD2 mutation status. Analyses in larger randomized datasets will provide additional information on the role of biomarkers in RCC. Clinical trial information: NCT02501096. [Table: see text]

A Randomized Study of Lenvatinib 18 mg vs 24 mg in Patients With Radioiodine-Refractory Differentiated Thyroid Cancer

BACKGROUND

Lenvatinib is a multikinase inhibitor approved to treat radioiodine-refractory differentiated thyroid cancer (RR-DTC) at a starting dose of 24 mg/day. This study explored, in a double-blinded fashion, whether a starting dose of 18 mg/day would provide comparable efficacy with reduced toxicity.

METHODS

Patients with RR-DTC were randomized to lenvatinib 24 mg/day or 18 mg/day. The primary efficacy endpoint was objective response rate as of week 24 (ORRwk24); the odds ratio noninferiority margin was 0.4. The primary safety endpoint was frequency of grade ≥3 treatment-emergent adverse events (TEAEs) as of week 24. Tumors were assessed using RECIST v1.1. TEAEs were monitored and recorded.

RESULTS

The ORRwk24 was 57.3% (95% CI 46.1, 68.5) in the lenvatinib 24-mg arm and 40.3% (95% CI 29.3, 51.2) in the lenvatinib 18-mg arm, with an odds ratio (18/24 mg) of 0.50 (95% CI 0.26, 0.96). As of week 24, the rates of TEAEs grade ≥3 were 61.3% in the lenvatinib 24-mg arm and 57.1% in the lenvatinib 18-mg arm, a difference of -4.2% (95% CI -19.8, 11.4).

CONCLUSION

A starting dose of lenvatinib 18 mg/day did not demonstrate noninferiority compared to a starting dose of 24 mg/day as assessed by ORRwk24 in patients with RR-DTC. The results represent a clinically meaningful difference in ORRwk24. The safety profile was comparable, with no clinically relevant difference between arms. These results support the continued use of the approved starting dose of lenvatinib 24 mg/day in patients with RR-DTC and adjusting the dose as necessary.

Long-term avelumab in advanced non-small-cell lung cancer: summaries and post hoc analyses from JAVELIN Solid Tumor

Background:

This study examined patients with advanced non-small-cell lung cancer who received long-term avelumab (anti-PD-L1) in a large phase Ib trial (JAVELIN Solid Tumor).

Methods:

Patients receiving >2 years of avelumab were reviewed and exploratory descriptive analyses were conducted.

Results:

Individuals with varying baseline characteristics who had received up to 6 years of avelumab were reviewed. Overall, 37/340 (10.9%) had received ≥2 years of treatment; in this subgroup, best response was complete response in 5.4%, partial response in 59.5% and stable disease in 29.7%; 51.4% had continued treatment beyond disease progression.

Conclusions:

In this study, 11% of patients with advanced non-small-cell lung cancer received ≥2 years of avelumab treatment and experienced prolonged response or continued clinical benefit.

Clinical Trial Registration:NCT02395172 (ClinicalTrials.gov)

Intralesional TTI-621, a novel biologic targeting the innate immune checkpoint CD47, in patients with relapsed or refractory mycosis fungoides or Sézary syndrome: a multicentre, phase 1 study

BACKGROUND

Intravenous TTI-621 (SIRPα-IgG1 Fc) was previously shown to have activity in relapsed or refractory haematological malignancies. This phase 1 study evaluated the safety and activity of TTI-621 in patients with percutaneously accessible relapsed or refractory mycosis fungoides, Sézary syndrome, or solid tumours. Here we report the clinical and translational results among patients with mycosis fungoides or Sézary syndrome.

METHODS

This multicentre, open-label, phase 1 study was conducted at five academic health-care and research centres in the USA. Eligible patients were aged 18 years or older; had injectable, histologically or cytologically confirmed relapsed or refractory cutaneous T-cell lymphoma (CTCL) or solid tumours; Eastern Cooperative Oncology Group performance status of 2 or less; and adequate haematological, renal, hepatic, and cardiac function. TTI-621 was injected intralesionally in a sequential dose escalation (cohorts 1-5; single 1 mg, 3 mg, or 10 mg injection or three 10 mg injections weekly for 1 or 2 weeks) and in expansion cohorts (cohorts 6-9; 2 week induction at the maximum tolerated dose; weekly continuation was allowed). In cohort 6, patients were injected with TTI-621 in a single lesion and in cohort 7, they were injected in multiple lesions. In cohort 8, TTI-621 was combined with pembrolizumab 200 mg injections per product labels. In cohort 9, TTI-621 was combined with the standard labelled dose of subcutaneous pegylated interferon alpha-2a 90 μg. The primary endpoint was the incidence and severity of adverse events. The study is registered with ClinicalTrials.gov, NCT02890368, and was closed by the sponsor to focus on intravenous studies with TTI-621.

FINDINGS

Between Jan 30, 2017, and March 31, 2020, 66 patients with mycosis fungoides, Sézary syndrome, other CTCL, or solid tumours were screened, 35 of whom with mycosis fungoides or Sézary syndrome were enrolled and received intralesional TTI-621 (escalation, n=13; expansion, n=22). No dose-limiting toxicities occurred; the maximum tolerated dose was not established. In the dose expansion cohorts, the maximally assessed regimen (10 mg thrice weekly for 2 weeks) was used. 25 (71%) patients had treatment-related adverse events; the most common (occurring in ≥10% of patients) were chills (in ten [29%] patients), injection site pain (nine [26%]), and fatigue (eight [23%]). No treatment-related adverse events were grade 3 or more or serious. There were no treatment-related deaths. Rapid responses (median 45 days, IQR 17-66) occurred independently of disease stage or injection frequency. 26 (90%) of 29 evaluable patients had decreased Composite Assessment of Index Lesion Severity (CAILS) scores; ten (34%) had a decrease in CAILS score of 50% or more (CAILS response). CAILS score reductions occurred in adjacent non-injected lesions in eight (80%) of ten patients with paired assessments and in distal non-injected lesions in one additional patient.

INTERPRETATION

Intralesional TTI-621 was well tolerated and had activity in adjacent or distal non-injected lesions in patients with relapsed or refractory mycosis fungoides or Sézary syndrome, suggesting it has systemic and locoregional abscopal effects and potential as an immunotherapy for these conditions.

FUNDING

Trillium Therapeutics.

Avelumab as second-line therapy for metastatic, platinum-treated urothelial carcinoma in the phase Ib JAVELIN Solid Tumor study: 2-year updated efficacy and safety analysis

Background

Anti-programmed cell death ligand 1 (PD-L1)/programmed cell death 1 antibodies have shown clinical activity in platinum-treated metastatic urothelial carcinoma, resulting in regulatory approval of several agents, including avelumab (anti-PD-L1). We report ≥2-year follow-up data for avelumab treatment and exploratory subgroup analyses in patients with urothelial carcinoma.

Methods

Patients with previously treated advanced/metastatic urothelial carcinoma, pooled from two cohorts of the phase Ib JAVELIN Solid Tumor trial, received avelumab 10 mg/kg every 2 weeks until disease progression, unacceptable toxicity or withdrawal. End points included best overall response and progression-free survival (PFS) per RECIST V.1.1, overall survival (OS) and safety. Post hoc analyses included objective response rates (ORRs) in subgroups defined by established high-risk/poor-prognosis characteristics and association between time to response and outcome.

Results

249 patients received avelumab; efficacy was assessed in 242 postplatinum patients. Median follow-up was 31.9 months (range 24–43), and median treatment duration was 2.8 months (range 0.5–42.8). The confirmed ORR was 16.5% (95% CI 12.1% to 21.8%; complete response in 4.1% and partial response in 12.4%). Median duration of response was 20.5 months (95% CI 9.7 months to not estimable). Median PFS was 1.6 months (95% CI 1.4 to 2.7 months) and the 12-month PFS rate was 16.8% (95% CI 11.9% to 22.4%). Median OS was 7.0 months (95% CI 5.9 to 8.5 months) and the 24-month OS rate was 20.1% (95% CI 15.2% to 25.4%). In post hoc exploratory analyses, avelumab showed antitumor activity in high-risk subgroups, including elderly patients and those with renal insufficiency or upper tract disease; ORRs were numerically lower in patients with liver metastases or low albumin levels. Objective response achieved by 3 months versus later was associated with longer OS (median not reached (95% CI 18.9 months to not estimable) vs 7.1 months (95% CI 5.2 to 9.0 months)). Safety findings were consistent with previously reported 6-month analyses.

Conclusions

After ≥2 years of follow-up, avelumab showed prolonged efficacy and acceptable safety in patients with platinum-treated advanced/metastatic urothelial carcinoma, including high-risk subgroups. Survival appeared longer in patients who responded within 3 months. Long-term safety findings were consistent with earlier reports with avelumab treatment in this patient population.

A phase I/II study of rovalpituzumab tesirine in delta-like 3-expressing advanced solid tumors

Delta-like protein 3 (DLL3) is highly expressed in solid tumors, including neuroendocrine carcinomas/neuroendocrine tumors (NEC/NET). Rovalpituzumab tesirine (Rova-T) is a DLL3-targeting antibody-drug conjugate. Patients with NECs and other advanced DLL3-expressing tumors were enrolled in this phase I/II study (NCT02709889). The primary endpoint was safety. Two hundred patients were enrolled: 101 with NEC/NET (large-cell NEC, gastroenteropancreatic NEC, neuroendocrine prostate cancer, and other NEC/NET) and 99 with other solid tumors (melanoma, medullary thyroid cancer [MTC], glioblastoma, and other). The recommended phase II dose (RP2D) was 0.3 mg/kg every 6 weeks (q6w) for two cycles. At the RP2D, grade 3/4 adverse events included anemia (17%), thrombocytopenia (15%), and elevated aspartate aminotransferase (8%). Responses were confirmed in 15/145 patients (10%) treated at 0.3 mg/kg, including 9/69 patients (13%) with NEC/NET. Rova-T at 0.3 mg/kg q6w had manageable toxicity, with antitumor activity observed in patients with NEC/NET, melanoma, MTC, and glioblastoma.

Pralsetinib for patients with advanced or metastatic RET-altered thyroid cancer (ARROW): a multi-cohort, open-label, registrational, phase 1/2 study

BACKGROUND

Oncogenic alterations in RET represent important therapeutic targets in thyroid cancer. We aimed to assess the safety and antitumour activity of pralsetinib, a highly potent, selective RET inhibitor, in patients with RET-altered thyroid cancers.

METHODS

ARROW, a phase 1/2, open-label study done in 13 countries across 71 sites in community and hospital settings, enrolled patients 18 years or older with RET-altered locally advanced or metastatic solid tumours, including RET-mutant medullary thyroid and RET fusion-positive thyroid cancers, and an Eastern Co-operative Oncology Group performance status of 0-2 (later limited to 0-1 in a protocol amendment). Phase 2 primary endpoints assessed for patients who received 400 mg once-daily oral pralsetinib until disease progression, intolerance, withdrawal of consent, or investigator decision, were overall response rate (Response Evaluation Criteria in Solid Tumours version 1.1; masked independent central review) and safety. Tumour response was assessed for patients with RET-mutant medullary thyroid cancer who had received previous cabozantinib or vandetanib, or both, or were ineligible for standard therapy and patients with previously treated RET fusion-positive thyroid cancer; safety was assessed for all patients with RET-altered thyroid cancer. This ongoing study is registered with clinicaltrials.gov, NCT03037385, and enrolment of patients with RET fusion-positive thyroid cancer was ongoing at the time of this interim analysis.

FINDINGS

Between Mar 17, 2017, and May 22, 2020, 122 patients with RET-mutant medullary and 20 with RET fusion-positive thyroid cancers were enrolled. Among patients with baseline measurable disease who received pralsetinib by July 11, 2019 (enrolment cutoff for efficacy analysis), overall response rates were 15 (71%) of 21 (95% CI 48-89) in patients with treatment-naive RET-mutant medullary thyroid cancer and 33 (60%) of 55 (95% CI 46-73) in patients who had previously received cabozantinib or vandetanib, or both, and eight (89%) of nine (95% CI 52-100) in patients with RET fusion-positive thyroid cancer (all responses confirmed for each group). Common (≥10%) grade 3 and above treatment-related adverse events among patients with RET-altered thyroid cancer enrolled by May 22, 2020, were hypertension (24 patients [17%] of 142), neutropenia (19 [13%]), lymphopenia (17 [12%]), and anaemia (14 [10%]). Serious treatment-related adverse events were reported in 21 patients (15%), the most frequent (≥2%) of which was pneumonitis (five patients [4%]). Five patients [4%] discontinued owing to treatment-related events. One (1%) patient died owing to a treatment-related adverse event.

INTERPRETATION

Pralsetinib is a new, well-tolerated, potent once-daily oral treatment option for patients with RET-altered thyroid cancer.

FUNDING

Blueprint Medicines.

Correlation of Performance Status and Neutrophil-Lymphocyte Ratio with Efficacy in Radioiodine-Refractory Differentiated Thyroid Cancer Treated with Lenvatinib

Background: Radioiodine-refractory differentiated thyroid cancer (RR-DTC) has a low 10-year patient-survival rate and is challenging to treat. Lenvatinib is a multikinase inhibitor approved for the treatment of RR-DTC. This study aims to assess Eastern Cooperative Oncology Group performance status (ECOG PS) and neutrophil-to-lymphocyte ratio (NLR) as prognostic markers for patients with RR-DTC treated with lenvatinib. Methods: In this retrospective analysis of the Study of (E7080) LEnvatinib in Differentiated Cancer of the Thyroid (SELECT), patients randomly assigned to receive lenvatinib were classified according to baseline ECOG PS (0 or 1) or baseline NLR (≤3 or >3). The effects of baseline ECOG PS and NLR on progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) were evaluated. In addition, the effects of baseline ECOG PS on the change in diameter of target lesions and correlations between baseline NLR and the sums of the diameters of target lesions were calculated. Results: Among patients who received lenvatinib, patients with a baseline ECOG PS of 0 had statistically improved PFS (hazard ratio [HR] 0.52; 95% confidence interval [CI 0.35-0.77]; p = 0.001), OS (HR 0.42 [CI 0.26-0.69]; p = 0.0004), and ORR (odds ratio [OR] 3.51 [CI 2.02-6.10]; p < 0.0001) compared with patients with a baseline ECOG PS of 1. Patients who received lenvatinib with a baseline NLR ≤3 also had improved PFS (HR 0.43 [CI 0.29-0.65]; p < 0.0001) and OS (HR 0.48 [CI 0.29-0.78]; p = 0.0029) versus patients with a baseline NLR >3. Moreover, patients with a baseline NLR ≤3 had a trend toward increased ORR (OR 1.57 [CI 0.94-2.64]; p = 0.08) compared with patients with a baseline NLR >3. Treatment-emergent adverse events were generally similar among patients who received lenvatinib, irrespective of patients' ECOG PS at baseline. Conclusion: Lower ECOG PS and NLR may provide prognostic value for improved efficacy in patients with RR-DTC. ClinicalTrials.gov no. NCT01321554.

Characterization and Management of Adverse Reactions in Patients with Advanced Endometrial Carcinoma Treated with Lenvatinib Plus Pembrolizumab

BACKGROUND

The combination of lenvatinib plus pembrolizumab has shown efficacy in treatment of advanced endometrial carcinoma (that is not microsatellite instability-high or mismatch repair deficient) following prior systemic therapy in any setting in the open-label, single-arm, phase Ib/II Study 111/KEYNOTE-146. With the exception of hypothyroidism, the safety profile of the combination was comparable to that of each monotherapy. Given the medical complexity and fragility of patients with endometrial carcinoma, further characterization of adverse reactions (ARs) associated with treatment will help health care professionals to optimize treatment with lenvatinib plus pembrolizumab combination therapy.

PATIENTS AND METHODS

In Study 111/KEYNOTE-146, patients received lenvatinib at a starting dose of 20 mg orally once daily and pembrolizumab 200 mg intravenously every 3 weeks. Selected ARs (hypertension, fatigue, nausea/vomiting, diarrhea, decreased appetite/weight loss, hypothyroidism, palmar-plantar erythrodysesthesia syndrome, musculoskeletal pain, stomatitis, and proteinuria) were chosen for detailed post hoc analyses.

RESULTS

Median times to first onset of the selected ARs in this analysis all occurred within the first 10 weeks of treatment. Of the selected ARs, grade ≥3 severity of fatigue, hypertension, and nausea occurred in ≥5% of patients. Overall incidence of hypothyroidism was 51%, primarily of grade 2 severity (46%). Most of the ARs assessed were managed with a combination of study drug dose modifications and concomitant medications.

CONCLUSION

No new safety signals were identified and the toxicity profile in this study was manageable with supportive medications, dose interruptions, and/or lenvatinib dose reductions. This analysis provides AR management guidance for patients with endometrial cancer receiving lenvatinib plus pembrolizumab combination therapy.

IMPLICATIONS FOR PRACTICE

Lenvatinib plus pembrolizumab has shown efficacy in the treatment of patients with advanced endometrial carcinoma (that is, not microsatellite instability-high or mismatch repair deficient) following at least one prior systemic therapy in any setting. Patients may experience toxicity associated with this combination, including adverse reactions of hypertension, fatigue, nausea/vomiting, diarrhea, decreased appetite/weight loss, hypothyroidism, palmar-plantar erythrodysesthesia syndrome, musculoskeletal pain, stomatitis, and proteinuria. These adverse reactions may be managed with a combination of concomitant supportive care medications and judicious lenvatinib dose modifications. This article provides context and guidance for the recognition and management of adverse reactions in patients receiving lenvatinib plus pembrolizumab.

Pralsetinib for RET fusion-positive non-small-cell lung cancer (ARROW): a multi-cohort, open-label, phase 1/2 study

BACKGROUND

Oncogenic alterations in RET have been identified in multiple tumour types, including 1-2% of non-small-cell lung cancers (NSCLCs). We aimed to assess the safety, tolerability, and antitumour activity of pralsetinib, a highly potent, oral, selective RET inhibitor, in patients with RET fusion-positive NSCLC.

METHODS

ARROW is a multi-cohort, open-label, phase 1/2 study done at 71 sites (community and academic cancer centres) in 13 countries (Belgium, China, France, Germany, Hong Kong, Italy, Netherlands, Singapore, South Korea, Spain, Taiwan, the UK, and the USA). Patients aged 18 years or older with locally advanced or metastatic solid tumours, including RET fusion-positive NSCLC, and an Eastern Cooperative Oncology Group performance status of 0-2 (later limited to 0-1 in a protocol amendment) were enrolled. In phase 2, patients received 400 mg once-daily oral pralsetinib, and could continue treatment until disease progression, intolerance, withdrawal of consent, or investigator decision. Phase 2 primary endpoints were overall response rate (according to Response Evaluation Criteria in Solid Tumours version 1·1 and assessed by blinded independent central review) and safety. Tumour response was assessed in patients with RET fusion-positive NSCLC and centrally adjudicated baseline measurable disease who had received platinum-based chemotherapy or were treatment-naive because they were ineligible for standard therapy. This ongoing study is registered with ClinicalTrials.gov, NCT03037385, and enrolment of patients with treatment-naive RET fusion-positive NSCLC was ongoing at the time of this interim analysis.

FINDINGS

Of 233 patients with RET fusion-positive NSCLC enrolled between March 17, 2017, and May 22, 2020 (data cutoff), 92 with previous platinum-based chemotherapy and 29 who were treatment-naive received pralsetinib before July 11, 2019 (efficacy enrolment cutoff); 87 previously treated patients and 27 treatment-naive patients had centrally adjudicated baseline measurable disease. Overall responses were recorded in 53 (61%; 95% CI 50-71) of 87 patients with previous platinum-based chemotherapy, including five (6%) patients with a complete response; and 19 (70%; 50-86) of 27 treatment-naive patients, including three (11%) with a complete response. In 233 patients with RET fusion-positive NSCLC, common grade 3 or worse treatment-related adverse events were neutropenia (43 patients [18%]), hypertension (26 [11%]), and anaemia (24 [10%]); there were no treatment-related deaths in this population.

INTERPRETATION

Pralsetinib is a new, well-tolerated, promising, once-daily oral treatment option for patients with RET fusion-positive NSCLC.

FUNDING

Blueprint Medicines.

Lenvatinib plus pembrolizumab in patients with either treatment-naive or previously treated metastatic renal cell carcinoma (Study 111/KEYNOTE-146): a phase 1b/2 study

BACKGROUND

Despite advances in the first-line treatment of metastatic renal cell carcinoma (RCC), there is an unmet need for options to address disease progression during or after treatment with immune checkpoint inhibitors (ICIs). Pembrolizumab and lenvatinib are active as monotherapies in RCC; thus, we aimed to evaluate the combination of lenvatinib plus pembrolizumab in these patients.

METHODS

We report results of the metastatic RCC cohort from an open-label phase 1b/2 study of lenvatinib plus pembrolizumab in patients aged at least 18 years with selected solid tumours and an Eastern Cooperative Oncology Group performance status of 0-1. Oral lenvatinib at 20 mg was given once daily along with intravenous pembrolizumab at 200 mg once every 3 weeks. Patients remained on study drug treatment until disease progression, development of unacceptable toxicity, or withdrawal of consent. Efficacy was analysed in patients with clear cell metastatic RCC receiving study drug by previous therapy grouping: treatment naive, previously treated ICI naive (previously treated with at least one line of therapy but not with an anti-PD-1 or anti-PD-L1 ICI), and ICI pretreated (ie, anti-PD-1 or anti-PD-L1) patients. Safety was analysed in all enrolled and treated patients. The primary endpoint was the objective response rate at week 24 per immune-related Response Evaluation Criteria In Solid Tumors (irRECIST) by investigator assessment. This trial is registered with ClinicalTrials.gov (NCT02501096) and with the EU Clinical Trials Register (EudraCT2017-000300-26), and is closed to new participants.

FINDINGS

Between July 21, 2015, and Oct 16, 2019, 145 patients were enrolled in the study. Two patients had non-clear cell RCC and were excluded from the efficacy analysis (one in the treatment-naive group and one in the ICI-pretreated group); thus, the population evaluated for efficacy comprised 143 patients (n=22 in the treatment-naive group, n=17 in the previously treated ICI-naive group, and n=104 in the ICI-pretreated group). All 145 enrolled patients were included in the safety analysis. The median follow-up was 19·8 months (IQR 14·3-28·4). The number of patients with an objective response at week 24 by irRECIST was 16 (72·7%, 95% CI 49·8-89·3) of 22 treatment-naive patients, seven (41·2%, 18·4-67·1) of 17 previously treated ICI-naive patients, and 58 (55·8%, 45·7-65·5) of 104 ICI-pretreated patients. Of 145 patients, 82 (57%) had grade 3 treatment-related adverse events and ten (7%) had grade 4 treatment-related adverse events. The most common grade 3 treatment-related adverse event was hypertension (30 [21%] of 145 patients). Treatment-related serious adverse events occurred in 36 (25%) patients, and there were three treatment-related deaths (upper gastrointestinal haemorrhage, sudden death, and pneumonia).

INTERPRETATION

Lenvatinib plus pembrolizumab showed encouraging antitumour activity and a manageable safety profile and might be an option for post-ICI treatment of metastatic RCC.

FUNDING

Eisai and Merck Sharp & Dohme.

Initial results of a first-in-human, dose escalation study of a cell-based vaccine in HLA A*02+ patients (pts) with recurrent, locally advanced or metastatic HPV16+ solid tumors: SQZ-PBMC-HPV-101

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Background: Ineffective MHC-I presentation of tumor antigens to CD8+ T cells limits T cell activation and the efficacy of cancer vaccines. The Cell Squeeze technology drives peripheral blood mononuclear cells (PBMCs) through a microfluidic chip leading to temporary cell membrane disruption and delivery of HPV16 E6 and E7 antigens cytosolically. These antigen presenting cells (APC) were matured with CpG7909 and were not genetically modified. Preclinically, this approach showed improvement in MHC-I presentation for human and murine cells. In murine tumor studies, m-SQZ-PBMC-HPV elicited robust CD8+ T cell responses and improved anti-tumor effects when compared to other vaccine modalities. Methods: SQZ-PBMC-HPV-101 included pts with incurable HPV16+ cancers progressing after unlimited prior therapy, ECOG 0-1, adequate organ function and a biopsiable lesion. After leukapheresis at the study site, manufacturing of the cryopreserved product took < 24 hours with a vein-to-vein time of approx. 1 week. Out-patient SQZ-PBMC-HPV was given IV q 3 weeks without a conditioning regimen. Double antigen priming (DP) was introduced with Cohort 3 and occurred on Cycle 1 Days 1 and 2. Maximum treatment duration for each patient was determined by the cell batch size. Response was assessed via RECIST 1.1 and iRECIST. Investigational biomarkers were measured pre- and post-treatment. Results: 12 pts [anal (7), head and neck (3), and cervical (2)] were dosed in 3 cohorts (3 pts in 0.5 x10e6/kg, 5 pts in 2.5 x10e6/kg, and 4 pts in 2.5x 10e6/kg [DP]). Median lines of prior Tx were 4 (range 1 - 7) and all but one pt were pretreated with checkpoint inhibitors (CPI); 10 pts had liver or lung metastases. All batches of SQZ-PBMC-HPV demonstrated CD8 activation in vitro after thawing, and batch size did not limit therapy duration at dose levels tested to date. Median number of doses were 3 (3 - 10), 3 (2 - 4), and 3 (3 – 4) in the 3 cohorts, respectively. One pt (10 doses) remained on study for 42 weeks. Tx was well-tolerated and there were no DLTs, Grade (G) >3 related SAEs or related G >3 AEs. One pt in cohort 1 experienced both a G2 infusion-related reaction and cytokine release syndrome. One pt in cohort 2 was not evaluable for DLT. Four out of 10 evaluable pts had stable disease per RECIST 1.1 as the best response. Preliminary tumor analyses pre- and post-therapy indicated increased immune activity in some patients after SQZ infusion. Conclusions: SQZ-PBMC-HPV-101 demonstrated clinical feasibility of the Cell Squeeze technology and favorable tolerability of engineered APCs. The study allows for the characterization of the immunogenicity of engineered APCs in humans. Preliminary results warrant the testing in combination with CPI. Efficacy, safety, and correlative biomarker data will be presented, from pre- and post-therapy biopsies and blood samples. Clinical trial information: NCT04084951.

A first-in-human study of AO-176, a highly differentiated anti-CD47 antibody, in patients with advanced solid tumors

2516

Background: AO-176 is a humanized IgG2 antibody that specifically targets CD47. Expressed by multiple tumor types, CD47 binds to signal regulatory protein a (SIRPa) on phagocytes, including macrophages and dendritic cells. The CD47-SIRPa complex results in a “don’t eat me” signal that allows the tumor to escape removal by the innate immune system, disabling the generation of an adaptive immune response. The differentiated mechanisms of action of AO-176 include promotion of phagocytosis, direct tumor cell killing through programmed cell death type III and induction of damage associated molecular patterns/immunogenic cell death, preferentially binding to tumor cells vs. normal cells, and enhanced binding at an acidic pH as found in tumor microenvironments. AO-176 has negligible binding to RBCs. Methods: In a phase 1/2 first-in-human study (NCT03834948) of AO-176, pts with advanced solid tumors associated with high CD47 expression and an ECOG PS of 0-1 were enrolled into escalating dose cohorts of AO-176 given IV every 7 days. Objectives included evaluation of safety, dose-limiting toxicity (DLT) and recommended phase 2 dose (RP2D), antitumor activity, pharmacokinetic (PK) parameters and exploratory biomarkers. Results: As of 4 Jan 2021, 27 pts were enrolled (median age 64 years; 67% female; 67% ECOG PS 1; median [range] of 4 [1-7] prior therapies for metastatic disease). Dose levels of 1, 3, 10, 20 and 20 (using step-up dosing) mg/kg were evaluated in >250 infusions. Most common (>10%) treatment-related adverse events (TRAEs) of any grade were thrombocytopenia and infusion-related reaction (IRR) (33% each), anemia (22%) with no evidence of hemolysis, nausea (19%), and fatigue (15%). The only G3+ TRAE occurring in >10% of pts was asymptomatic, brief thrombocytopenia (22%). No platelet transfusions were given. DLTs included IRRs in 2 pts dosed at 20 mg/kg, and asymptomatic thrombocytopenia and a cerebrovascular accident in 1 pt each in the 20 mg/kg step-up cohort. The RP2D was 10 mg/kg. Implementation of additional pre-medication and a 6-hr infusion duration in cycle 1 eliminated subsequent IRRs. Dexamethasone tapering and shortening of the infusion duration to 2 hrs was successful in all pts after cycle 1. Interim PK analysis of AO-176 demonstrated consistent exposure with linear PK. The T1/2 was ̃5 days. One pt with endometrial carcinoma who had not responded to any of 4 prior systemic regimens had a confirmed PR and remains on study for >1 year. 7 pts had SD as a best response, with 2 pts (endometrial carcinoma, gastric cancer) on study for >6 mos. Conclusions: AO-176 is a well-tolerated, differentiated anti-CD47 therapeutic. Durable anti-tumor activity was observed. Evaluations of AO-176 in combination with paclitaxel in pts with select solid tumors (NCT03834948) and as a single-agent in pts with multiple myeloma (NCT04445701) are ongoing. Clinical trial information: NCT03834948.

Encorafenib and binimetinib with or without nivolumab in treating patients with metastatic radioiodine refractory BRAF V600 mutant thyroid cancer

TPS6085

Background: Differentiated thyroid cancer is the most common endocrine malignancy and has a high frequency of actionable molecular aberrations including BRAF V600E mutations (45%), RET fusions (10%), and NTRK fusions ( < 2%). FDA approved systemic therapies for metastatic radioiodine refractory differentiated thyroid cancer (RR-DTC) include multikinase inhibitors (Lenvatinib and sorafenib), NTRK inhibitors (larotrectinib and entrectinib for NTRK fusion+ cancers), and RET inhibitors (selpercatinib and pralsetinib for RET fusion+ cancers). Previous phase II clinical trials showed clinical efficacy with first and second generation BRAF inhibitors in patients with BRAF mutant RR-DTC. BRAF inhibitors have not yet been FDA approved for treatment of BRAF mutant RR-DTC. Effective therapeutic options for patients with BRAF mutant RR-DTC remains an important unmet clinical need. BRAF mutant thyroid cancers often show elevated expression of PD-L1. Additionally, BRAF inhibition results in increased expression of PD-L1 in thyroid cancer. This clinical trial seeks to evaluate the safety and efficacy of encorafenib plus binimetinib with or without nivolumab in patients with BRAF mutant metastatic RR-DTC. Encorafenib and binimetinib are highly selective and potent oral inhibitors of BRAF and MEK, respectively. Nivolumab is a potent inhibitor of the immune co-inhibitory receptor programmed cell death protein 1 (PD-1). Methods: This is a phase II, single institution, open-label, randomized clinical trial evaluating the combinations of (Arm 1) encorafenib 450 mg/day + binimetinib 45 mg twice daily and (Arm 2) encorafenib 450 mg/day + binimetinib 45 mg twice daily + nivolumab 480 mg I.V. every 4 weeks in patients with metastatic BRAF mutant RR-DTC. The trial will enroll 20 patients in each arm and treatment will be given in 28 day cycles for up to 2 years. Eligible patients must have metastatic/unresectable BRAF mutant RR-DTC, an ECOG performance status of 0-1 and adequate bone marrow, liver and kidney function. Patients with CNS metastases are included if the metastases have been treated and remained stable or are asymptomatic and ≤10 mm in diameter. Patients may be systemic therapy naïve or have previously been treated with multikinase inhibitors. Prior therapy with BRAF, MEK or immune checkpoint inhibitors is exclusionary. The primary endpoint is confirmed objective response rate (ORR) determined by RECIST v1.1 with restaging imaging every 12 weeks. Secondary endpoints include progression free survival, overall survival, and safety/tolerability (CTCAE v5.0). Arms 1 and 2 will be evaluated independently and are not powered for direct comparison. The trial design includes continuous toxicity monitoring with a Pocock-type stopping boundary. This clinical trial is in progress and 3 patients have been enrolled. Clinical trial information: NCT04061980.

The LEAP program: lenvatinib plus pembrolizumab for the treatment of advanced solid tumors

Tumor progression and immune evasion result from multiple oncogenic and immunosuppressive signals within the tumor microenvironment. The combined blockade of VEGF and inhibitory immune checkpoint signaling has been shown to enhance immune activation and tumor destruction in preclinical models. The LEAP clinical trial program is evaluating the safety and efficacy of lenvatinib (a multikinase inhibitor) plus pembrolizumab (a PD-1 inhibitor) across several solid tumor types. Preliminary results from ongoing trials demonstrate robust antitumor activity and durable responses across diverse tumor types with a manageable safety profile. Thus, lenvatinib plus pembrolizumab is anticipated to be an important potential new regimen for several solid cancers that currently have limited therapeutic options.

Clinical trial registration: NCT03884101 , NCT03713593 , NCT03820986 , NCT03776136 , NCT03797326 , NCT03829319 , NCT03829332 , NCT03976375 , NCT04428151 , NCT04199104 , NCT03898180 , NCT04246177 (ClinicalTrials.gov).

Clinical activity of the RET inhibitor pralsetinib (BLU-667) in patients with RET fusion–positive solid tumors

467

Background: Recent tumor-agnostic drug approvals have resulted in a paradigm shift in cancer treatment away from organ/histology specific indications to biomarker-guided tumor-agnostic approaches. Pralsetinib is a potent and selective RET inhibitor, which has recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of adults with metastatic RET fusion–positive non-small cell lung cancer (NSCLC) and is under New Drug Application review for RET mutant thyroid cancers by the FDA. RET fusions occur in up to approximately 7‒8% of patients with gastrointestinal malignancies, including pancreatic, liver, and colorectal cancers. There are currently no approved selective RET inhibitors for patients with RET fusion–positive solid tumors other than NSCLC and thyroid cancer. Here, we present data on the clinical activity of pralsetinib in patients with RET fusion–positive solid tumor types other than NSCLC enrolled in the Phase I/II ARROW study (NCT03037385). Methods: ARROW consists of a phase I dose escalation (30–600 mg once [QD] or twice daily) followed by a phase II expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives are overall response rate (ORR), per RECICT v1.1 and safety. Results: A total of 13 patients with RET fusion–positive thyroid cancer (12 papillary, 1 poorly differentiated; enrollment cutoff July 11, 2019) and 14 patients with RET fusion–positive solid tumors other than NSCLC and thyroid (3 pancreatic, 3 colon, 2 cholangiocarcinoma, 6 other; enrollment cutoff November 19, 2019) were enrolled in ARROW and received pralsetinib. At the February 13, 2020, data cutoff, the ORR (blinded central review) in response-evaluable patients with RET fusion–positive thyroid cancer was 91% (10/11; 95% CI: 59‒100) and disease control rate was 100% (95% CI: 72‒100). Treatment was ongoing in 7 of 11 patients. In RET fusion–positive solid tumors other than NSCLC and thyroid, ORR (investigator’s assessment) was 50% (6/12; 95% CI: 21‒79) and responses were observed in all patients with pancreatic cancer (3/3) and cholangiocarcinoma (2/2). Treatment was ongoing in 6 of 12 patients, including 2 of 3 patients with pancreatic cancer and 1 of 2 patients with cholangiocarcinoma. Responses were observed across multiple fusion genotypes. In the 27 patients with RET fusion–positive tumors other than NSCLC, most frequent treatment-related adverse events (TRAEs) were grade 1–2, and included anemia (33%), increased aspartate aminotransferase (33%), decreased white blood cell count (33%), hypertension (30%), increased alanine aminotransferase (26%), hyperphosphatemia (19%), and neutropenia (19%). No patients discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing. Clinical trial information: NCT03037385.

Lenvatinib Plus Pembrolizumab in Patients With Advanced Endometrial Cancer

PURPOSE

Patients with advanced endometrial carcinoma have limited treatment options. We report final primary efficacy analysis results for a patient cohort with advanced endometrial carcinoma receiving lenvatinib plus pembrolizumab in an ongoing phase Ib/II study of selected solid tumors.

METHODS

Patients took lenvatinib 20 mg once daily orally plus pembrolizumab 200 mg intravenously once every 3 weeks, in 3-week cycles. The primary end point was objective response rate (ORR) at 24 weeks (ORRWk24); secondary efficacy end points included duration of response (DOR), progression-free survival (PFS), and overall survival (OS). Tumor assessments were evaluated by investigators per immune-related RECIST.

RESULTS

At data cutoff, 108 patients with previously treated endometrial carcinoma were enrolled, with a median follow-up of 18.7 months. The ORRWk24 was 38.0% (95% CI, 28.8% to 47.8%). Among subgroups, the ORRWk24 (95% CI) was 63.6% (30.8% to 89.1%) in patients with microsatellite instability (MSI)-high tumors (n = 11) and 36.2% (26.5% to 46.7%) in patients with microsatellite-stable tumors (n = 94). For previously treated patients, regardless of tumor MSI status, the median DOR was 21.2 months (95% CI, 7.6 months to not estimable), median PFS was 7.4 months (95% CI, 5.3 to 8.7 months), and median OS was 16.7 months (15.0 months to not estimable). Grade 3 or 4 treatment-related adverse events occurred in 83/124 (66.9%) patients.

CONCLUSION

Lenvatinib plus pembrolizumab showed promising antitumor activity in patients with advanced endometrial carcinoma who have experienced disease progression after prior systemic therapy, regardless of tumor MSI status. The combination therapy had a manageable toxicity profile.

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.).

Lenvatinib (LEN) plus pembrolizumab (PEMBRO) for early-line treatment of advanced/recurrent endometrial cancer (EC)

6083

Background: As part of an ongoing phase Ib/II study (NCT02501096) in patients (pts) with selected solid tumors, LEN (20 mg PO QD) + PEMBRO (200 mg IV Q3W) displayed substantial and durable antitumor activity in advanced EC. In previously treated EC that was not microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR; n=94 pts), the objective response rate (ORR) by independent imaging review (IIR) per RECIST 1.1 was 38.3% (95% CI 28.5–48.9). In this post hoc analysis, we assessed 2 subgroups of pts with previously treated, advanced, non MSI-H or dMMR EC who received LEN + PEMBRO in an early-treatment setting. Methods: Pts were examined in 2 subgroups: (1) Pts with only 1 prior line of cytotoxic therapy regardless of surgical stage or setting (adjuvant treatment for local-regional disease or treatment for metastatic disease); and (2) pts from subgroup 1 with local-regional disease at diagnosis who received only adjuvant cytotoxic therapy. There were no restrictions on prior hormonal or chemoradiation therapies in either subgroup. Tumor responses were assessed by IIR per RECIST 1.1. Results: Subgroup 1 included 63 pts and subgroup 2 had 21 pts. ORR (95% CI) was 41.3% (29.0–54.4) for subgroup 1 and 57.1% (34.0–78.2) for subgroup 2. Additional efficacy outcomes are summarized in the table. In subgroup 1, treatment-related adverse events (TRAEs) occurred in 62 (98%) pts (42 [67%] ≥ grade 3). TRAEs led to study-drug interruption of one or both drugs in 43 (68%) pts and dose reductions of LEN in 42 (67%) pts; 12 (19%) pts discontinued one or both drugs due to a TRAE. Serious TRAEs occurred in 18 (29%) pts and 2 (3%) pts died from a TRAE. The safety profile for subgroup 2 was generally similar to the profile for subgroup 1. Conclusions: The efficacy of LEN + PEMBRO for early-line treatment of advanced non MSI-H or dMMR EC appears promising. No new safety signals have emerged. A phase III study of LEN + PEMBRO vs paclitaxel + carboplatin for first-line treatment in advanced or recurrent EC is underway. Clinical trial information: NCT02501096. [Table: see text]

Clinical activity of the RET inhibitor pralsetinib (BLU-667) in patients with RET fusion+ solid tumors

109

Background: RET gene fusions are targetable oncogenic drivers in multiple tumor types, including up to 20% of papillary thyroid cancers (PTC). Pralsetinib is an investigational, highly potent, selective inhibitor of oncogenic RET alterations. In the registration-enabling Phase 1/2 ARROW study (NCT03037385), pralsetinib demonstrated an overall response rate (ORR; response-evaluable patients [REP], central review) of 73% (19/26) in treatment-naïve patients and 61% (49/80; 2 pending confirmation) in platinum-exposed patients with RET fusion+ non-small cell lung cancer (NSCLC) and was well tolerated (data cut-off November 18, 2019). We provide an update on the clinical activity of pralsetinib in other RET fusion+ solid tumor types. Methods: ARROW consists of a phase 1 dose escalation (30–600 mg once [QD] or twice daily) followed by a phase 2 expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives were ORR and safety. Results: As of November 18, 2019, 29 patients with metastatic solid tumor types other than NSCLC (16 PTC, 1 undifferentiated thyroid, 3 pancreatic, 3 colon, 6 other) bearing a RET fusion have received pralsetinib. Efficacy data are presented for REP enrolled by July 11, 2019. In patients with thyroid cancer that is RET fusion+, ORR (investigator assessment) was 75% (9/12; all confirmed). Median (range) duration of response (DOR) was 14.5 (3.7+, 16.8) months (mo), with 67% of responding patients continuing treatment. Two patients with stable disease were continuing treatment at 11.5+ and 19.3+ mo. In other RET fusion+ cancers, ORR was 60% (3/5; all confirmed) with partial responses in 2/2 patients with pancreatic cancer (DOR 5.5, 7.4+ mo) and 1 patient with intrahepatic bile duct carcinoma (DOR 7.5 mo). Two patients with colon cancer had stable disease for 7.3 and 9.3 mo. Responses were observed across multiple fusion genotypes. In the entire safety population (all patients treated with 400 mg QD pralsetinib, regardless of diagnosis; n = 354), most treatment-related adverse events (TRAEs) were grade 1-2, and included increased aspartate aminotransferase (31%), anemia (22%), increased alanine aminotransferase (21%), constipation (21%) and hypertension (20%). Only 4% of patients in the safety population discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing and still enrolling patients in this cohort. Clinical trial information: NCT03037385.

A phase I/II study of rovalpituzumab tesirine in delta-like 3-expressing, advanced solid tumors

3552

Background: Delta-like 3 (DLL3) is highly and specifically expressed in solid tumors, such as neuroendocrine carcinomas (NECs), malignant melanoma (MM), and medullary thyroid carcinoma (MTC). Rovalpituzumab tesirine (Rova-T) is a DLL3-targeting antibody-drug conjugate. Methods: This Phase 1/2 study (NCT02709889) enrolled patients with relapsed/refractory DLL3+ (>1% by IHC) advanced solid tumors and ECOG performance status of 0-1. Rova-T was given IV at 0.2, 0.3, or 0.4 mg/kg on d 1 of each 6-wk cycle (q6wk) for dose escalation (3+3 design) in disease-specific cohorts in Phase I. The recommended Phase 2 dose (RP2D) was tested in Phase II. Safety and dose-limiting toxicities (DLTs) were primary endpoints; efficacy outcomes were secondary endpoints. Results: The study enrolled 200 patients; 101 had NECs (large cell NEC [n=13], neuroendocrine prostate cancer [n=21], high-grade gastroenteropancreatic NEC [n=36], other [n=31]) and 99 had other solid tumors (MM [n=20], MTC [n=13], glioblastoma [GBM; n=23], other [n=43]). The median age was 61 y (range, 28-84); 63% were male. The RP2D was 0.3 mg/kg q6wk for 2 cycles in all cohorts. There were 7 DLTs in 5 patients: 2 with 0.2 mg/kg (Grade [Gr] 3 photosensitivity reaction, Gr 3 dyspnea), 2 with 0.3 mg/kg (1 with Gr 2 effusion, Gr 3 tumor lysis syndrome, and Gr 3 rhabdomyolysis; 1 with Gr 4 kidney injury), and 1 with 0.4 mg/kg (Gr 4 thrombocytopenia). Despite only 1 DLT identified with 0.4 mg/kg, the totality of the safety data suggested that this dose is not well tolerated. Common adverse events (AEs) in patients given 0.3 mg/kg (n=145) are shown (Table). Serious AEs occurred in 77/145 patients (53%), most commonly (≥3%) malignant neoplasm progression (n=18; 12%), pleural effusion (n=7; 5%), pericardial effusion (n=6; 4%), and dyspnea (n=5; 3%). The objective response rate (ORR) was 11% (21/200): 14 had NEC, 2 had MM, 2 had MTC, 2 had small cell carcinoma (SCC) not of lung origin (all partial responses), and 1 had GBM (complete response). In patients with NECs given 0.3 mg/kg, ORR, clinical benefit rate, and progression-free survival trended in favor of those with high DLL3-expressing tumors (≥50% by IHC) which represented 51% of NECs. Conclusions: Rova-T was tolerable in patients with advanced solid tumors at 0.3 mg/kg q6wk for 2 cycles. Antitumor activity was observed in patients with NEC, MM, MTC, SCC, and GBM. Clinical trial information: NCT02709889 . [Table: see text]

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.

A mutation-specific, single-arm, phase 2 study of dovitinib in patients with advanced malignancies

Background: Receptor tyrosine kinases (RTKs) play key roles in tumorigenesis. The multi-RTK inhibitor dovitinib has demonstrated promising antitumor activity in multiple cancers.

Patients and Methods: In this phase 2, open-label, single-arm study, patients with advanced malignancies with RTK-pathway genetic aberrations whose disease progressed on/following standard treatment received dovitinib (500 mg/day; 5-days-on/2-days-off). The primary endpoint was clinical benefit rate (CBR; complete response, partial response [PR], or stable disease [SD] for ≥ 16 weeks).

Results: Of 80 patients enrolled, common tumors included gastrointestinal stromal tumors (GIST; 20.0%), colorectal cancer (CRC; 18.8%), and ovarian cancer (10.0%). Patients were heavily pretreated (median prior lines = 4; 67.5% had ≥ 3 prior lines). Genetic aberrations included cKIT (28.8%), FGFR3 (15.0%), and RET (15.0%). The CBR was 13.8%; one PR (GIST) and 10 SD (adenoid cystic [n = 3]; ovarian [n = 3]; GIST [n = 2]; CRC [n = 1]; gastroesophageal junction [n = 1]). The most common treatment-related adverse events were fatigue, diarrhea, nausea, and vomiting.

Conclusions: In this heterogeneous patient population, the safety profile was acceptable for dovitinib therapy. A subset of patients with RTK pathway-activated tumors experienced clinical benefit. However, the primary endpoint was not met, suggesting further refinement of predictive biomarkers is required.

Phase IB/II Trial of Lenvatinib Plus Pembrolizumab in Patients With Advanced Renal Cell Carcinoma, Endometrial Cancer, and Other Selected Advanced Solid Tumors

PURPOSE

Modulation of vascular endothelial growth factor–mediated immune suppression via angiogenesis inhibition may augment the activity of immune checkpoint inhibitors. We report results from the dose-finding and initial phase II expansion of a phase Ib/II study of lenvatinib plus pembrolizumab in patients with selected advanced solid tumors.

METHODS

Eligible patients had metastatic renal cell carcinoma (RCC), endometrial cancer, squamous cell carcinoma of the head and neck (SCCHN), melanoma, non–small-cell lung cancer (NSCLC), or urothelial cancer. The primary objective of phase Ib was to determine the maximum tolerated dose (MTD) for lenvatinib plus pembrolizumab (200 mg intravenously every 3 weeks). In the preplanned phase II cohort expansion, the primary objective was objective response rate at week 24 (ORR_{week 24}) at the recommended phase II dose.

RESULTS

Overall, 137 patients were enrolled during phase Ib (n = 13) and the initial phase II expansion (n = 124). Two dose-limiting toxicities (DLTs; grade 3 arthralgia and grade 3 fatigue) were reported in the initial dose level (lenvatinib 24 mg/d plus pembrolizumab). No DLTs were observed in the subsequent dose–de-escalation cohort, establishing the MTD and recommended phase II dose at lenvatinib 20 mg/d plus pembrolizumab. ORR_week24 was as follows: RCC, 63% (19/30; 95% CI, 43.9% to 80.1%); endometrial cancer, 52% (12/23; 95% CI, 30.6% to 73.2%); melanoma, 48% (10/21; 95% CI, 25.7% to 70.2%); SCCHN, 36% (8/22; 95% CI, 17.2% to 59.3%); NSCLC, 33% (7/21; 95% CI, 14.6% to 57.0%); and urothelial cancer 25% (5/20; 95% CI, 8.7% to 49.1%). The most common treatment-related adverse events were fatigue (58%), diarrhea (52%), hypertension (47%), and hypothyroidism (42%).

CONCLUSION

Lenvatinib plus pembrolizumab demonstrated a manageable safety profile and promising antitumor activity in patients with selected solid tumor types.

Efficacy and Safety of Avelumab Treatment in Patients With Advanced Unresectable Mesothelioma: Phase 1b Results From the JAVELIN Solid Tumor Trial

Importance

Patients with malignant mesothelioma whose disease has progressed after platinum and pemetrexed treatment have limited options. Anti-programmed cell death 1 (PD-1) antibodies have antitumor activity in this disease, but little is known about the activity of anti-programmed cell death ligand 1 (PD-L1) antibodies in patients with mesothelioma.

Objective

To assess the efficacy and safety of avelumab in a cohort of patients with previously treated mesothelioma.

Design, Setting, and Participants

Phase 1b open-label study (JAVELIN Solid Tumor) in patients with unresectable mesothelioma that progressed after platinum and pemetrexed treatment, enrolled at 25 sites in 3 countries between September 9, 2014, and July 22, 2015.

Interventions

Participants received avelumab, 10 mg/kg, every 2 weeks until disease progression, unacceptable toxic effects, or withdrawal from the study.

Main Outcomes and Measures

Prespecified end points included confirmed best overall response based on Response Evaluation Criteria In Solid Tumors, version 1.1; duration of response; progression-free survival (PFS); overall survival (OS); PD-L1 expression-based analyses; and safety.

Results

Of 53 patients treated with avelumab, the median age was 67 (range, 32-84) years; 32 (60%) were male. As of December 31, 2016, median follow-up was 24.8 (range, 16.8-27.8) months. Twenty patients (38%) had 3 or more previous lines of therapy (median, 2; range, 1-8). The confirmed objective response rate (ORR) was 9% (5 patients; 95% CI, 3.1%-20.7%), with complete response in 1 patient and partial response in 4 patients. Responses were durable (median, 15.2 months; 95% CI, 11.1 to not estimable months) and occurred in patients with PD-L1-positive tumors (3 of 16; ORR, 19%; 95% CI, 4.0%-45.6%) and PD-L1-negative tumors (2 of 27; ORR, 7%; 95% CI, 0.9%-24.3%) based on a 5% or greater PD-L1 cutoff. Disease control rate was 58% (31 patients). Median PFS was 4.1 (95% CI, 1.4-6.2) months, and the 12-month PFS rate was 17.4% (95% CI, 7.7%-30.4%). Median OS was 10.7 (95% CI, 6.4-20.2) months, and the median 12-month OS rate was 43.8% (95% CI, 29.8%-57.0%). Five patients (9%) had a grade 3 or 4 treatment-related adverse event, and 3 (6%) had a grade 3 or 4 immune-related, treatment-related adverse event. There were no treatment-related deaths.

Conclusions and Relevance

Avelumab showed durable antitumor activity and disease control with an acceptable safety profile in a heavily pretreated cohort of patients with mesothelioma.

Trial Registration

ClinicalTrials.gov identifier: NCT01772004.

Abstract C087: Phase 1 study of DCC-3014, an oral inhibitor of CSF1R, to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics in patients with advanced solid tumors, including diffuse-type tenosynovial giant cell tumor

Background: DCC-3014 is an orally administered kinase inhibitor targeting the switch pocket of colony-stimulating factor 1 receptor (CSF1R). DCC-3014 exhibits approximately 100-fold selectivity from kinases homologous to CSF1R, such as KIT, and greater selectivity against 300 other human kinases. Tumor-associated macrophages (TAMs) are dependent on CSF1R kinase activity for proliferation and maintenance of the immunosuppressive phenotype. TAMs are known to enable tumor cells escape from immune surveillance. DCC-3014 is designed to exhibit an antitumor effect by inhibition of immunosuppressive TAMs or other CSF1R signaling-dependent pro-tumor activities. In addition, tenosynovial giant cell tumor (TGCT) is a rare, monoarticular disease known to be caused by the translocation in the CSF1 gene leading to overexpression of CSF1. Anti-CSF1R therapies have shown clinical activity in diffuse TGCT. Methods: This study is a multicenter, first-in-human study of DCC-3014 to determine a recommended Phase 2 dose (RP2D) or maximally tolerated dose (MTD) with a 3+3 dose escalation design and evaluate the safety, efficacy, pharmacokinetics (PK) and pharmacodynamics (PD) of DCC-3014 in advanced solid tumors, including diffuse-type TGCT [NCT03069469]. Results: As of June 2, 2019, the study is ongoing in the dose escalation phase and has enrolled 32 patients with advanced solid tumors in 7 cohorts. The first cohort was initiated at 10 mg daily. Based on preliminary PK analysis from the first cohort, subsequent cohorts utilized a loading dose followed by a maintenance dosing schedule to achieve steady-state exposures more rapidly. The median age of patients was 61 years old and 69% were female with the median of 4 lines of prior anti-cancer treatment. No dose limiting toxicities (DLTs) have been seen in the assessed cohorts. Most commonly seen treatment-emergent adverse events (TEAEs &gt;20%) were constipation (38%), vomiting (34%), diarrhea (31%), nausea (31%), decreased appetite (25%), abdominal pain (22%), and dyspnea (22%) whereas diarrhea, nausea and fatigue were reported as treatment-related AEs seen in &gt;10% of all patients (13%). TEAEs were mostly Grade 1 or 2. Serious AEs (SAEs) were seen in 16 patients, none of which were related to DCC-3014. Exposure was approximately dose proportional. PD effects were seen for dose levels at 10 mg and above, and induction of the CSF1R ligand, CSF-1, was seen up to 148-fold from baseline. The RP2D or MTD has not been selected or reached. Conclusion: DCC-3014 in this study was generally well tolerated in patients with advanced solid tumors and showed approximately dose-proportional exposure and PD changes as expected. Further evaluation is ongoing to determine the RP2D or MTD. Data from the TGCT cohort will be presented at a future meeting.

Citation Format: Matthew H Taylor, Stephen Leong, Ying Su, Cynthia B Leary, Xiaoyan Li, Keisuke Kuida, Rodrigo Ruiz-Soto, Todd Bauer. Phase 1 study of DCC-3014, an oral inhibitor of CSF1R, to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics in patients with advanced solid tumors, including diffuse-type tenosynovial giant cell tumor [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C087. doi:10.1158/1535-7163.TARG-19-C087

Efficacy and safety of buparlisib, a PI3K inhibitor, in patients with malignancies harboring a PI3K pathway activation: a phase 2, open-label, single-arm study

Background: Phosphatidylinositol 3-kinase (PI3K) pathway activation plays a key role in tumorigenesis and has been associated with poor prognosis and resistance to multiple therapies in various cancers. Results: There were 146 patients enrolled; common tumor types were colorectal, sarcoma, and ovarian. Tumors had PI3K pathway alterations and a median of four mutations with tissue-specific patterns of mutation burden (lowest: sarcoma [2.5]; highest: esophagus, germ cell tumor, skin non-melanoma, vaginal [7]). The number of prior therapies did not correlate with the number of genetic alterations (Pearson r = -0.037). The clinical benefit rate was 15.1% (n = 22). An additional patient had an unconfirmed complete response. The most common adverse events were fatigue, nausea, hyperglycemia, decreased appetite, and diarrhea. Patient and Methods: In this phase 2, open-label, single-arm study, patients with solid or hematologic malignancies with PI3K pathway activation and progression on or after standard treatment received buparlisib (100 mg once daily). The primary endpoint was clinical benefit rate per local investigator assessment (response or stable disease at ≥16 weeks). Conclusions: Buparlisib was well tolerated, however efficacy was limited despite selection of PI3K pathway aberrations. Future studies may provide insight into buparlisib efficacy by refining the molecular selection of different tumor types.

Activity and tolerability of BLU-667, a highly potent and selective RET inhibitor, in patients with advanced RET-altered thyroid cancers

6018

Background: RET alterations are targetable oncogenic drivers in ~90% of advanced medullary thyroid cancer (MTC) and 20% of papillary thyroid cancer (PTC), yet no selective RET inhibitors are approved. BLU-667 is an investigational highly potent and selective RET inhibitor targeting oncogenic RET alterations including those that confer resistance to multikinase inhibitors (MKIs). We provide an update on the expanded experience of BLU-667 in RET-altered thyroid cancer from the registration-enabling ARROW study (NCT03037385). Methods: ARROW is a global DE (30-600 mg daily [QD or BID]) and dose expansion (DX; 400 mg QD) study in pts with advanced solid tumors. Primary objectives are response rate (ORR; RECIST 1.1) and safety. Results: As of 19Dec2018, 60 pts with RET-mutated MTC (M918T [37], C634R/S/W [8], V804M [4], other/pending [11]) and 5 pts with RET-fusion+ PTC (NCOA4 [3], CCDC6 [2]) received BLU-667 (37 DE, 28 DX). 58% had prior MKI therapy. Among 49 response-evaluable MTC pts, ORR is 47% (95% CI: 33, 62; 2 complete and 21 partial responses (PR); 4 PR pending confirmation; 25 stable disease; 1 progressive disease). 96% (22/23) of responding pts continue treatment; 15 with response duration ≥ 6 months. 2/4 evaluable PTC pts had PR; all 5 enrolled PTC pts continue treatment at 8-11 months. Responses in MTC occur regardless of MKI resistance (prior cabozantinib/vandetanib: ORR 46% (12/26)) or RET genotype (PR in 2/3 evaluable pts with V804M). Disease control rate in MTC pts is 98%. Rapid plasma clearance of RET variants and marked reduction in CEA and calcitonin is observed. Treatment-related toxicity in MTC/PTC pts, generally low-grade and reversible (28% had grade 3 events, no grade 4/5 events, no events requiring discontinuation), includes decreased WBC (23%), increased AST (17%), increased ALT, blood creatinine, and phosphate, hypertension, and decreased neutrophils (all 15%). Conclusions: BLU-667 demonstrates potent, durable and broad antitumor activity and is well tolerated in MTC/PTC pts regardless of MKI resistance and may significantly improve outcomes for pts with RET-altered thyroid cancers. Enrollment of the expansion is ongoing with registrational intent. Clinical trial information: NCT03037385.

Influence of tumor size and Eastern Cooperative Oncology Group performance status (ECOG PS) at baseline on patient (pt) outcomes in lenvatinib-treated radioiodine-refractory differentiated thyroid cancer (RR-DTC)

6081

Background: In SELECT, lenvatinib significantly improved progression-free survival (PFS) of pts with RR-DTC versus placebo (18.3 v 3.6 months; hazard ratio [HR]: 0.21 [99% CI: 0.14, 0.31]; P<0.001). Here we examine the treatment of RR-DTC with lenvatinib in relation to tumor size (sum of all targeted lesions) and ECOG PS. Methods: In this post hoc analysis of SELECT with pts randomized to receive lenvatinib, Kaplan-Meier estimates of time to ECOG PS ≥2 were calculated for subgroups of pts according to baseline ECOG PS or tumor size. Objective response rate (ORR) and Kaplan-Meier estimates of overall survival (OS) and PFS according to ECOG PS (0 or 1) at baseline were calculated. Correlations between ECOG PS at baseline (0 or 1) and maximum tumor shrinkage were calculated using one-way analysis of variance. Results: Pts with ECOG PS 0 or 1 at baseline had similar demographic and disease characteristics. ORR was 78.5% and 51.0% for pts with ECOG PS 0 and 1 at baseline, respectively (odds ratio [95% CI]: 3.508 [2.018, 6.097]). Mean maximum percent decrease in tumor size was significantly greater in pts with baseline ECOG PS 0 (-46.13%) versus pts with ECOG PS 1 (-37.16%; P=0.0017). For pts with ECOG PS 1 at baseline, time to ECOG PS ≥2 was numerically shorter with tumor size >60 mm versus tumor size ≤60 mm (HR [95% CI]: 1.450 [0.708, 2.967]). Additional results are summarized in the table. Conclusions: Among pts with RR-DTC, PFS, OS, ORR, and time to ECOG ≥2 were generally better for patients with lower ECOG PS or smaller tumor size at baseline. These results may indicate that it is beneficial to start lenvatinib in pts with RR-DTC early, before ECOG PS worsens and tumor size increases. Clinical trial information: NCT01321554. [Table: see text]

Clinical activity and tolerability of BLU-667, a highly potent and selective RET inhibitor, in patients (pts) with advanced RET-fusion+ non-small cell lung cancer (NSCLC)

9008

Background: RET fusions are targetable oncogenic drivers in up to 2% of NSCLC, yet no selective RET inhibitors are approved. BLU-667 is an investigational highly potent and selective RET inhibitor targeting oncogenic RET alterations, including those that confer resistance to multikinase inhibitors (MKIs). We provide an update on the registration-enabling ARROW study (NCT03037385) of BLU-667 in pts with RET-fusion+ NSCLC. Methods: The global ARROW study includes DE (30-600 mg daily [QD or BID]) and dose expansion (DX) at the recommended phase 2 dose (RP2D; 400 mg QD) in pts with advanced solid tumors. Primary objectives are overall response rate (ORR; RECIST 1.1) and safety. Results: As of 19Dec2018, 79 pts (21 DE, 58 DX) with advanced RET fusion+ NSCLC (44 KIF5B, 16 CCDC6, 19 other/pending) received BLU-667. Median number of prior therapies was 2 (range 0-8) and includes chemotherapy (76%), immunotherapy (41%), and MKI (27%). 39% had baseline brain metastases. ORR among 57 response-evaluable pts with measurable disease and at least one follow-up disease assessment was 56% (95% CI: 42, 69; 32 partial responses (PR), 9 PR pending confirmation, 20 stable disease, 5 progressive disease). 91% (29/32) of responding pts remain on treatment; 6 have achieved response duration ≥ 6 months. Disease control rate (DCR) was 91% (52/57). Among 30 pts at the RP2D previously treated with platinum chemotherapy, ORR was 60% (18 PRs; 7 pending confirmation). Responses occur regardless of prior treatment or RET fusion genotypes. Intracranial activity has been observed with shrinkage of brain metastases. 80% of NSCLC pts treated at RP2D remain on treatment and only 3% discontinued due to related adverse event. In NSCLC patients, treatment-related toxicity (TRT), generally low-grade and reversible (28% had ≥ grade 3 events), included increased AST (22%), hypertension (18%), increased ALT (17%), constipation (17%), fatigue (15%) and decreased neutrophils (15%). Conclusions: BLU-667 demonstrated potent, durable and broad antitumor activity and was well tolerated in pts with advanced RET-fusion+ NSCLC. Enrollment of the expansion is ongoing with registrational intent. Clinical trial information: NCT03037385.

SGNTV-001: Open label phase 2 study of tisotumab vedotin for locally advanced or metastatic disease in solid tumors

TPS3160

Background: Tisotumab vedotin (TV) is being developed for patients with cervical cancer and other solid tumors known to express Tissue Factor (TF). Expression of TF on tumor cells has been associated with poor prognosis in several tumor types. Four tumor types were chosen for this study based on unmet medical need and TF expression. TV is an antibody-drug conjugate composed of a TF-targeted fully human monoclonal immunoglobulin G1 conjugated via a protease-cleavable valine citrulline linker to the drug monomethyl auristatin E (MMAE). TV-mediated delivery of MMAE drives antitumor activity through cytotoxic cell killing and has been shown to induce immunogenic cell death (ICD). In preclinical studies, TV treatment resulted in potent and long-lasting tumor regression in TF-expressing xenograft models derived from a variety of solid cancers, including patient-derived xenograft models with heterogeneous TF expression. TV has shown preliminary evidence of activity in heavily pretreated patients with many TF-expressing tumor types in the GEN701 phase 1 study. Methods: SGNTV-001 (innovaTV 207) is a global, open label, multicenter phase 2 trial designed to assess the safety, tolerability, and activity of TV for the treatment of solid tumors. (NCT03485209; EudraCT 2017-005076-26). Patients are currently enrolling in 4 cohorts: colorectal cancer (CRC), squamous non-small cell lung cancer (NSCLC), exocrine pancreatic adenocarcinoma, and squamous cell carcinoma of the head and neck (SCCHN). Patients must have measureable disease per RECIST v1.1 that has progressed despite standard of care systemic treatment in the locally advanced or metastatic setting (up to 3 prior lines for CRC, 2 for squamous NSCLC and SCCHN, and 1 for pancreatic adenocarcinoma) and have an ECOG score of 0 or 1. The primary endpoint is investigator-determined confirmed ORR as measured by RECIST v1.1. Secondary objectives include DOR, PFS, OS, DCR, and TTR, as well as safety and pharmacokinetic parameters. The first patient was enrolled in July 2018 and the study is currently enrolling across 16 sites in the US (as of January 2019) with additional sites opening in EU countries. Clinical trial information: NCT03485209.

Lenvatinib (len) plus pembrolizumab (pembro) in patients (pts) with advanced melanoma previously exposed to anti–PD-1/PD-L1 agents: Phase 2 LEAP-004 study

TPS9594

Background: Pembro, a PD-1 inhibitor, has shown effective antitumor activity, deep and durable responses, and survival benefit in treatment-naive pts and those with previously treated metastatic melanoma. Len, a potent inhibitor of VEGF receptors 1-3, FGF receptors 1-4, PDGF receptor α, RET, and KIT, combined with a PD-1 inhibitor showed antitumor activity superior to either agent alone in preclinical models of colorectal and lung cancer. Additionally, len plus pembro showed anti-tumor activity and was well-tolerated (24-wk ORR, 47.6%; TRAE: gr 3/4, 67%; gr 5, 0%) in pts with advanced melanoma previously treated with 0-2 therapies in the phase 1b/2 KEYNOTE-146 trial. The efficacy and safety of len plus pembro combination therapy will be evaluated in an open-label, phase 2 trial of pts with advanced melanoma that progressed on PD-1/PD-L1 inhibitor therapy (NCT03776136). Methods: Key inclusion criteria: age ≥18 years, histologically/cytologically confirmed unresectable stage III-IV melanoma that progressed (per iRECIST) within 12 weeks of last dose of an approved PD-1/PD-L1 inhibitor therapy (≥2 doses as monotherapy or combined with other therapies), measurable disease, ECOG PS 0/1, no active autoimmune disease, and adequate organ function. Pts must provide a baseline tumor sample. Pts will receive len 20 mg/day orally plus pembro 200 mg IV Q3W for approximately 2 years (35 doses of pembro), after which they may receive len alone until PD or unacceptable toxicity. Response will be assessed per RECIST v1.1 based on blinded independent central review (BICR) Q9W until week 54, Q12W until week 102, and Q24W thereafter. Pts with CR may discontinue treatment after ≥24 weeks of therapy; eligible pts may continue treatment beyond initial RECIST- or iRECIST-defined PD. AEs will be assessed throughout treatment and for 90 days (120 days for serious AEs) after last dose and graded per NCI CTCAE v4.0. Pts will be followed-up for survival status Q12W. The primary efficacy end point is ORR per modified RECIST v1.1 (BICR). Key secondary end points are PFS and DOR per modified RECIST v1.1 (BICR), OS, and safety; an exploratory biomarker analysis is planned. Clinical trial information: NCT03776136.