CTNI-62. LONG-TERM EFFICACY AND SAFETY OF LAROTRECTINIB IN PATIENTS WITH TROPOMYOSIN RECEPTOR KINASE (TRK) FUSION PRIMARY CENTRAL NERVOUS SYSTEM (CNS) TUMORS

BACKGROUND

Larotrectinib is a highly selective TRK inhibitor that demonstrated an objective response rate (ORR) of 30% and a 24-week disease control rate (DCR) of 73% across 33 evaluable adult and pediatric patients with TRK fusion primary CNS tumors, as of July 2020 (Doz et al, Neuro Oncol 2021). We report updated data on an expanded dataset.

METHODS

Patients with TRK fusion primary CNS tumors in two clinical trials (NCT02637687, NCT02576431) were included. Responses were investigator-assessed.

RESULTS

As of July 2021, 38 patients with TRK fusion primary CNS tumors (median age, 10.8 [range 1.3–79.0] years) were identified: high-grade glioma (HGG; n = 23), low-grade glioma (LGG; n = 9), and other (n = 6). Sixteen (42%) patients had ≥ 2 prior systemic therapies. ORR for 37 evaluable patients was 30% (95% confidence interval [CI] 16–47): three complete responses, eight partial responses, 21 stable disease (16 patients ≥ 24 weeks), and five progressive disease. For pediatric patients (n = 28), the ORR was 39% (95% CI 22–59). For pediatric patients with HGG and LGG, ORRs were 43% (95% CI 18–71) and 38% (95% CI 9–76), respectively. ORRs for patients with 0, 1, 2, and ≥ 3 prior therapies were 33%, 20%, 38%, and 38%, respectively. Median time to response was 1.9 months. The 24-week DCR was 73% (95% CI 56–86). Median duration of response (DoR) was not reached; 12-month DoR rate was 64%. Median progression-free survival was 16.5 months (95% CI 6.7–not estimable). Median overall survival (OS) was not reached; 24-month OS rate was 65%. Treatment duration ranged from 0.1+ to 38.7+ months. Treatment-related adverse events (TRAEs) were mostly Grade 1–2. No patients discontinued treatment due to TRAEs.

CONCLUSION

Larotrectinib demonstrated a high DCR, rapid and durable responses, and a manageable safety profile in patients with TRK fusion primary CNS tumors.

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses.

Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial.

iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival.

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Implementing comprehensive molecular profiling into standard of care is feasible.

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Temporal heterogeneity is observed, indicating the value of sequential analyses.

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Molecularly matched treatments are applied in a minority of patients despite clinical benefit.

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Poor performance status & limited access to drugs within trial hamper targeted treatment.

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The multidisciplinary tumour board is crucial in translating findings into clinical decision making.

Abstract SY09-01: A comprehensive European approach to precision pediatric cancer medicine

Cure rates for pediatric malignancies have stagnated at around 80% for two decades. A “more of the same” approach will likely not help a considerable proportion of the remaining ~20% of children who cannot be cured to date, thus implying an urgent need for innovative treatment strategies. The aim of the INFORM (INdividualized Therapy FOr Relapsed Malignancies in Childhood) program is to translate next generation molecular diagnostics into a personalized, biomarker-driven treatment strategy. The program consists of two major pillars: the INFORM registry providing a molecular screening platform and the INFORM2 series of exploratory biomarker-driven phase I/II trials, conducted through the European Innovative Therapies for Children with Cancer (ITCC) network. This is complemented by an international public-private preclinical testing platform, ITCC-P4, which aims at systematic and rigorous preclinical filtering of novel assets for a potential indication in the pediatric space. INFORM is a multi-national registry, open across nine European countries, offering comprehensive real-time molecular profiling for pediatric patients with no standard treatment options. INFORM is complemented by corresponding programs in France, the Netherlands, the UK and Denmark to cover most of the European population. To date, more than 1,100 patients have been registered and profiled through INFORM, using whole-exome and low-coverage whole genome sequencing, as well as RNA transcriptome sequencing and DNA methylation analysis. In 2019 alone, almost 400 patients were recruited. A comprehensive analysis of the first ~800 patients enrolled including a thorough primary-relapse study to investigate intra-individual tumor evolution is currently ongoing and first results will be presented. Potentially actionable targets of ‘moderate' or higher priority (which are reported in the weekly interdisciplinary molecular tumor board and documented in the online database) were identified in approximately half of all patients, with many having been treated with mechanism-of-action based therapies on the basis of the generated data. Recently we have also added real-time drug profiling on short-term tumor cell cultures as an additional screening tool in the context of the COMPASS Consortium. The long-term goals of this program are 1) to inform a series of early-phase, cross-entity, combination clinical trials to improve access to innovative treatment approaches for pediatric patients (e.g., INFORM2 trial series); and 2) to deliver evidence demonstrating that the molecular profiling is of clinical value to patients, in the assumption that these costs will be reimbursed by health insurances as part of routine standard-of-care for high-risk pediatric cancer patients. Within the preclinical platform ITCC-P4, consortium members have established and molecularly characterized more than 150 patient-derived xenograft models from pediatric solid tumors (target: 400 models). These are now being utilized for systematic single-mouse preclinical trials applying both standard-of-care treatments as well as innovative new drugs from the portfolios of participating companies in selected pediatric cancer (sub)-entities through standardized Mechanism-of-Action-based matching with pediatric tumor biology. Applying a uniform and comprehensive interdisciplinary strategy for molecular diagnostic, preclinical and early clinical activities in Europe, we hope to be able to tackle the challenge of pediatric very high-risk diseases in a more effective way.

Citation Format: Stefan M. Pfister, David TW Jones, Barbara C. Jones, Balasubramanian Gnana Prakash, Mirjam Blattner-Johnson, Elke Pfaff, Cornelis M. Van Tilburg, Sina Oppermann, Louis Stancato, Hubert Caron, Gilles Vassal, Kristian Pajtler, Natalie Jäger, Olaf Witt. A comprehensive European approach to precision pediatric cancer medicine [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr SY09-01.

Quality of life of adults and children with TRK fusion cancer treated with larotrectinib compared to the general population

3614

Background: NTRK gene fusions occur in diverse tumor types in adults and children. The selective TRK inhibitor, larotrectinib, has shown high response rates, durable disease control, and a favorable safety profile in patients (pts) with TRK fusion cancer. We report an expanded quality of life (QoL) analysis for pts treated with larotrectinib. Methods: QoL data were collected in two trials of larotrectinib in pts with TRK fusion cancer using EORTC QLQ-C30 (adults) and PedsQL (children) questionnaires, and were analyzed descriptively and longitudinally. EORTC QLQ-C30 global health scores (GHS) and PedsQL total scores range from 0 to 100, with higher scores indicating better QoL. We calculated the proportion of pts with normal/above and below normal QoL scores compared to values in the literature for the US general population. Results: By July 2019, 126 pts with TRK fusion cancer (74 adults, 24 children ≥2 yrs, and 28 infants <2 yrs) had received larotrectinib and completed baseline (BL) and ≥1 post-BL questionnaire. Most pts had clinically meaningful QoL improvements that reached or exceeded the minimally important difference (Table); a positive change from BL was also seen in infants: mean best change of 12.0 (SD 13.8). Of 52 adults with BL EORTC QLQ-C30 GHS at or above the population norm, 51 remained in this category on treatment and 1 moved into the below normal category. Of 22 adults with BL scores below the population norm, 20 moved into the normal/above normal category. All 9 children aged ≥2 yrs with BL PedsQL scores at or above the population norm remained in this category on treatment. Of 15 children with BL scores below the population norm, 10 moved into the normal/above normal category. Sustained QoL improvements (change from BL ≥0) occurred by 2 months of treatment in 69% of adults and 75% of children. Median duration of sustained improvement in EORTC QLQ-C30 GHS and PedsQL total score was 12.0 months (range 1.7–20.3) and not estimable (range 1.1–23.0), respectively. Conclusions: Adults and children with TRK fusion cancer treated with larotrectinib had rapid, clinically meaningful, and sustained improvements in QoL. Clinical trial information: NCT02576431, NCT02637687 . [Table: see text]

Growth modulation index (GMI) as a comparative efficacy measure of larotrectinib versus prior systemic treatments for TRK fusion cancer patients

e15638

Background: Larotrectinib is a highly selective TRK inhibitor that demonstrated high response rates and durable disease control in three phase I/II single-arm studies of patients (pts) with TRK fusion cancer. While single-arm studies are often used for rare cancer populations, they do not provide comparative data. GMI utilizes pts as their own control and can be used in this setting. GMI is the ratio of progression-free survival (PFS) on the current therapy to time to progression (TTP) on the most recent prior line of therapy. A GMI ≥1.33 has been used as a threshold of meaningful clinical activity. We report GMI for TRK fusion cancer pts treated with larotrectinib. Methods: Data were pooled from 3 clinical trials of pts with TRK fusion cancer treated with larotrectinib. A retrospective, exploratory analysis of GMI was conducted in pts who had been on larotrectinib and followed up for ≥6 mos or pts who discontinued early, and had ≥1 prior line of systemic treatment for locally advanced or metastatic disease. TTP on the prior line of therapy was investigator assessed. PFS on larotrectinib was determined by independent review committee per RECIST 1.1. Pts who had not progressed were not censored from the analysis. Results: As of July 15, 2019, 122 pts were eligible for analysis. Fifteen different tumor types were represented, the most common being soft tissue sarcoma in 26 pts (21%), infantile fibrosarcoma in 22 (18%), and thyroid in 21 (17%). Median GMI was 3.35 (range 0.00–337.00; Table); In metastatic pts (n = 81), the proportion with a GMI ≥1.33 was higher in pts with a complete or partial response vs non-responders (88% vs 42%). In the whole analysis set (N = 122), median TTP on prior line of treatment was 2.7 mos (95% CI 2.0–3.1) and median PFS on larotrectinib was 33.4 mos (95% CI 13.8–NE; HR 0.20 [95% CI 0.14–0.29]). In metastatic pts (n = 81), median TTP on prior line of treatment was 2.3 mos (95% CI 1.9–3.0) and median PFS on larotrectinib was 23.4 mos (95% CI 10.9–NE; HR 0.24 [95% CI 0.16–0.36]). Conclusions: Greater than two-thirds of pts with TRK fusion cancer treated with larotrectinib had a GMI ≥1.33, demonstrating a clinically meaningful improvement in PFS compared to TTP on their prior treatment. Clinical trial information: NCT02122913, NCT02576431, NCT02637687.

Abstract IA11: Pediatric precision oncology programs in Germany and Europe

The treatment of relapses from high-risk entities remains a major clinical challenge, thus the desperate need for precision medicine approaches. To serve this need, we have developed the INFORM registry study (INdividualized therapy FOr Relapsed Malignancies in Childhood), which attempts to rapidly generate personalized tumor profiles and identify therapeutic targets in a clinical diagnostic environment for relapse patients. The INFORM study assesses the feasibility of integrating rapid molecular profiling in the clinical management of pediatric cancer patients with progressive or relapsed high-risk malignancies. Whole-exome and low-coverage whole-genome sequencing are being performed on tumor and normal DNA, complemented with matched tumor RNA sequencing (Illumina HiSeq4000), DNA methylation profiling, and gene expression profiling (for outlier gene expression). To date, more than 400 patients were enrolled from &gt;50 centers in seven different countries (Germany, The Netherlands, Switzerland, Austria, Sweden, Finland, and Australia). The average turnaround time from tissue arrival to molecular results is 3 weeks. Actionable targets with at least “borderline” evidence (according to a prioritization score harmonized with the other major pediatric precision oncology programs across Europe) are being identified in ~50% of patients. Based on these findings, several patients were recruited onto ongoing clinical trials, or targeted therapeutics and/or patient-specific peptide vaccines were incorporated into individualized treatment regimes, with first reports of marked responses. Furthermore, we have established a systematic workflow for the reporting of hereditary predisposition, which is detected in ~7% of cases. In 2018, we will start recruiting patients onto several target-defined (entity independent) subtrials of the INFORM2 interventional trial series as well as the complementary counterpart conducted in France, the eSMART trial, which will collectively provide a portfolio of ~10 mechanism-of-action defined, investigator-initiated early phase clinical (combination) trials for pediatric patients at relapse within the European Innovative Therapies for Children with Cancer (ITCC) Consortium.

Citation Format: David T. W. Jones, Barbara C.Worst, Elke Pfaff, Cornelis M. Van Tilburg, Gnana Prakash Balasubramanian, Petra Fiesel, Kristian W. Pajtler, Angelika Freitag, Ruth Witt, Andreas E. Kulozik, Felix Sahm, Andreas von Deimling, Angelika Eggert, Uta Dirksen, Peter Lichter, David Capper, Olaf Witt, Stefan M. Pfister. Pediatric precision oncology programs in Germany and Europe [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr IA11.

The INFORM personalized medicine study for high-risk pediatric cancer patients

10509

Background: Relapses from high-risk tumors pose a major clinical challenge in pediatric oncology. The German INFORM registry (INdividualized therapy FOr Relapsed Malignancies in children) addresses this problem using integrated next-generation sequencing to rapidly identify patient-specific therapeutic targets. Methods: Whole-exome, low-coverage whole-genome and RNA sequencing is complemented with microarray-based DNA methylation profiling. Identified alterations are discussed and prioritized according to biological significance and potential druggability in a weekly molecular tumor board. Results: To date, 214 tumor samples of high-risk pediatric cancer patients have been profiled from 47 German centers, with 39% being sarcomas, 30% brain tumors, 13% neuroblastoma and 18% hematological or other malignancies. Turnaround time from tissue arrival to molecular results was 21 calendar days on average. In 14/214 patients (7%) we identified an underlying germline predisposition syndrome. In several cases there were discrepancies between the original histological diagnosis and our molecular findings, especially in brain tumors. We detected one or more potentially druggable alterations in 147/214 (69%) cases. Tyrosine kinases, the PI3K/mTOR pathway, MAPK pathway, and cell-cycle as well as transcriptional regulators were commonly affected. Based on these findings, targeted therapeutics were incorporated into the therapy regime in one-third of patients, with anecdotal reports of marked responses, including a patient with a pleomorphic sarcoma, where we detected a previously undescribed RAF-fusion, showing a partial remission upon RAF-inhibition. Conclusions: In summary, real-time comprehensive profiling of pediatric tumors provides valuable diagnostic information and identifies potential therapeutic targets. In parallel, the implementation of a systematic program for reverse-translational evaluation is ongoing. Recently, this nationwide effort has expanded to include patients from other countries. We will also recruit patients to the complementary eSMART and INFORM2 biomarker-driven, phase I/II combination trial series, to provide unprecedented access to targeted therapies in Europe.

Phase 1/2 study of the selective TRK inhibitor larotrectinib in pediatric patients with cancer

TPS10577

Background: Neurotrophin ligands and their receptors TRKA, TRKB, and TRKC (encoded by NTRK1, NTRK2, and NTRK3) are important for growth regulation, differentiation and survival of neurons. Translocations involving the NTRK1/2/3 kinase domain, mutations involving the TRK ligand-binding site, and amplifications of NTRK, have been described in diverse tumor types and may contribute to tumorigenesis. A broad range of pediatric malignancies have been found to harbor NTRK fusions, including infantile fibrosarcoma (IFS), spindle-cell sarcoma, congenital mesoblastic nephroma, pediatric papillary thyroid cancer, pediatric gliomas and Ph-like acute lymphoblastic leukemia. Larotrectinib is the first small-molecule selective inhibitor of TRKA, -B, and -C in clinical development and preliminary data from the adult phase 1 trial demonstrate prolonged responses in patients with TRK fusions and a favorable safety profile. Methods: We have initiated an open-label, multi-center, international Phase 1/2 study with larotrectinib in pediatric patients with solid tumors and primary CNS tumors (NCT02637687). Patients with advanced cancer between the ages of 1 year and 21 years are eligible, as well as patients as young as 1-month of age with a documented NTRK fusion. Patients with IFS who have not had definitive surgery are also eligible. Larotrectinib is administered orally twice daily on a continuous 28-day schedule. Dosing is based on body surface area. Larotrectinib is available in an oral liquid formulation and capsules. Following identification of the maximum tolerated dose of larotrectinib in the phase 1 portion, the phase 2 portion will commence. The phase 2 portion will enroll patients with NTRK-translocated tumors and measurable disease into three cohorts: 1) infantile fibrosarcoma; 2) extracranial solid tumors; and 3) primary CNS tumors. The primary endpoint for the phase 2 portion is objective response rate, with duration of response and progression free survival as secondary efficacy endpoints. Each phase 2 cohort will enroll in a single stage of up to 10 patients per cohort. Molecular abnormalities will be characterized through the analysis of archival tissue. Enrollment began in December 2015 and is ongoing. Clinical trial information: NCT02637687.