Subbiah, Vivek

4009 Background: Oncogenic FGFR2 alterations (fusions/rearrangements (f/r), amplifications, mutations) represent a broad therapeutic opportunity as they drive multiple solid tumors, particularly cholangiocarcinoma (CCA). However, off-isoform toxicity and on-target resistance limit the benefit of approved pan-FGFR inhibitors (FGFRi). RLY-4008 is the first potent, highly selective, oral FGFR2 inhibitor designed to overcome these limitations by targeting FGFR2 driver alterations and resistance mutations. Here, we present updated dose escalation results from ReFocus (NCT04526106), a seamless Phase I/II, open label study evaluating the safety and preliminary efficacy of RLY-4008 in patients (pts) with advanced, FGFR2-altered solid tumors. Methods: Adult pts received RLY-4008 BID, QD, QD discontinuous on a 4-week (wk) cycle following a Bayesian Optimal Interval design. Treatment-related adverse events (TRAEs), PK, ctDNA and anti-tumor activity (RECIST v1.1) were assessed. Results: As of 30 Jan 23, 116 pts (82 f/r, 27 mutation, 6 amplification) received RLY-4008 at doses of 20-200 mg/day, including 91 with CCA. 50% had prior FGFRi, and median lines of prior therapies was 3 (1-15). 28/46 ct-DNA-evaluable pts with CCA with prior FGFRi had ≥1 baseline resistance mutation, most commonly at FGFR2 N549X (23/46) or V564X (17/46). RLY-4008 had favorable PK with doses ≥40 mg QD providing FGFR2 occupancy ≥90%. 70 mg QD was the RP2D based on PK, safety, anti-tumor activity and exposure-dependent tumor regressions in FGFRi-naïve CCA f/r pts. Anti-tumor activity was observed in CCA and solid tumors across doses and FGFR2 alterations with radiographic tumor reductions in 74 (64%), SD/PR in 83 (72%), including 4/4 (100%) FGFRi-naïve CCA f/r pts at RP2D achieving confirmed PR. Clinically meaningful disease control and durable responses were observed in pts with FGFR2 f/r CCA. Overall, median treatment duration was 24 wks (range <1-108 wks). 105 pts discontinued (PD (81%), AE (3%), other (7%)). Across doses, most common TRAEs were low-grade PPE (57%), stomatitis (56%), dry mouth (38%), alopecia (28%), and dry eye (22%). No grade 4/5 TRAEs were observed. Conclusions: These encouraging dose escalation data confirm the broad therapeutic potential of highly selective FGFR2 targeting with RLY-4008 by demonstrating encouraging initial efficacy across FGFR2-altered solid tumors and genomic alterations, with a differentiated safety profile that avoids FGFR1- and FGFR4-related toxicity. Phase 2 of ReFocus continues across solid tumors and with registrational intent in FGFRi-naïve, FGFR2 f/r CCA. Clinical trial information: NCT04526106 . [Table: see text]

Summary Genome driven precision oncology has transformed the landscape of multiple cancers. However, access barriers exist. A recent study exemplified a direct-to-patient outreach program via social media through the implementation of a global program that offered free tumor genomic testing with a focus on rare cancers. See related article by Doe-Tetteh et al., p. 2445

Abstract Background: Oncogenic alterations (gene amplification, mutation, and fusion/rearrangements) of fibroblast growth factor receptor 2 (FGFR2) are rare and occur at varying frequencies across solid tumor types and have become critical therapeutic targets in drug development. First generation FGFR pan-kinase inhibitors non-selectively inhibit FGFR1-4 and are associated with dose limiting toxicities and narrow therapeutic windows. Off-isoform toxicity (FGFR1-hyperphosphatemia; FGFR4-diarrhea) and on-target acquired resistance have led to limited efficacy, which is primarily seen in FGFR2-fusion+ intrahepatic cholangiocarcinoma. Therapies that selectively target FGFR2 remain an unmet need in advanced breast cancer as well as other solid tumor types. RLY-4008 is a novel, oral FGFR2 inhibitor designed to overcome the limitations of pan-FGFR inhibitors (FGFRi) by potently and selectively targeting primary oncogenic FGFR2 alterations and acquired resistance mutations. RLY-4008 is &gt; 200-fold selective over FGFR1, &gt; 80- and &gt; 5000-fold selective over FGFR3 and FGFR4 respectively. Here we describe a phase 1/2 study to investigate the safety and antitumor activity in advanced FGFR2 altered cancers, including breast cancer. Methods: ReFocus is a phase 1/2 open label global study evaluating the safety and efficacy of RLY-4008 (NCT04526106) in adult patients with advanced unresectable and/or metastatic cancers harboring an FGFR2 alteration. Key eligibility criteria include: documented FGFR2 alteration in blood or tissue per local assessment, ECOG performance status of 0-1, disease that is refractory or not adequately responding to standard therapy, has no available standard therapy, or patient is intolerant of, or declined standard therapy (including pan-FGFRi), and measurable or evaluable disease per RECIST 1.1. FGFR2 alteration will be confirmed retrospectively by central laboratory assessment. Part 1 dose escalation employed the Bayesian Optimal Interval (BOIN) design to determine the MTD/RP2D of RLY-4008. Part 2 dose expansion is presently enrolling patients at the RP2D of RLY-4008 and includes 5 cohorts comprised of patients with: 1. FGFR2 fusion+ cholangiocarcinoma previously treated with an FGFRi; 2. FGFR2 fusion+ cholangiocarcinoma not previously treated with an FGFRi; 3. FGFR2 fusion+ solid tumors; 4. FGFR2 mutation+ solid tumors and 5. FGFR2 amplified solid tumors. Solid tumors in cohorts 3, 4 and 5 will have a focus in breast cancer. The primary endpoint is objective response rate (ORR); key secondary endpoints include: duration of response, safety and tolerability, correlation of FGFR2 genotype by central tissue assessment with antitumor response, characterization of PK profile, and quality of life. US enrollment began September 2020 and has expanded into Europe and Asia. Clinical trial information: NCT04526106. Citation Format: Suneel Kamath, David Tai, Irene Moreno, Hani Babiker, Zhaohui Jin, Changhoon Yoo, Fabien Ricard, Kai Yu Jen, Jim Coward, Jia Liu, Frans Opdam, Michael Millward, Mariano Ponz-Sarvise, Jeffrey Yachnin, Richard Kim, Joon Oh Park, Vivek Subbiah, Alison M. Schram. ReFocus: A Phase 1/2 Study of the Highly Selective FGFR2 Inhibitor, RLY-4008, in Patients with Advanced Solid Tumors Including Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-24-01.

Lay summaryImmunotherapy has changed the landscape of cancer treatment. However, the benefit of immunotherapy is seen only in some cases, with most patients experiencing cancer progression despite treatment with immunotherapy. To overcome this, combination immunotherapy treatments are being studied. Herein, we propose for a precision‐driven approach for patient selection to identify successful combinations of immunotherapy to improve outcomes for patients with cancer.

Abstract Purpose: Tilsotolimod is an investigational synthetic Toll-like receptor 9 (TLR9) agonist that has demonstrated antitumor activity in preclinical models. The ILLUMINATE-101 phase I study explored the safety, dose, efficacy, and immune effects of intratumoral (it) tilsotolimod monotherapy in multiple solid tumors. Patients and Methods: Patients with a diagnosis of refractory cancer not amenable to curative therapies received tilsotolimod in doses escalating from 8 to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Additional patients with advanced malignant melanoma were enrolled into an expansion cohort at the 8 mg dose. Objectives included characterizing the safety, establishing the dose, efficacy, and immunologic assessment. Blood samples and tumor biopsies of injected and noninjected lesions were obtained at baseline and 24 hours after treatment for immune analyses. Results: Thirty-eight and 16 patients were enrolled into the dose escalation and melanoma expansion cohorts, respectively. Deep visceral injections were conducted in 91% of patients. No dose-limiting toxicities (DLT) or grade 4 treatment-related adverse events were observed. Biopsies 24 hours after treatment demonstrated an increased IFN pathway signature and dendritic cell maturation. Immunologic profiling revealed upregulation of IFN-signaling genes and modulation of genes for checkpoint proteins. In the dose escalation cohort, 12 (34%) of 35 evaluable patients achieved a best overall response rate (ORR) of stable disease (SD), whereas 3 (19%) of 16 evaluable patients in the melanoma cohort achieved stable disease. Conclusions: Overall, tilsotolimod monotherapy was generally well tolerated and induced rapid, robust alterations in the tumor microenvironment. See related commentary by Punekar and Weber, p. 5007

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.

Abstract BRAF plus MEK inhibitor combinations are currently FDA-approved for melanoma, non–small cell lung cancer, and anaplastic thyroid cancer. The lack of clinical benefit with BRAF inhibition in BRAF V600–mutated colorectal cancer has prevented its tissue-agnostic drug development. We reviewed the AACR GENIE database for the prevalence of BRAF V600 mutations across tumor types. We reviewed the literature for case reports of clinical responses, outcomes in patients with BRAF V600 mutation—positive nonmelanoma malignancies who received BRAF inhibitor therapy, and data from published adult and pediatric trials. BRAF V600 mutations are prevalent across multiple nonmelanoma malignancies (&gt;40 different tumor types), lead to oncogene addiction, and are clinically actionable in a broad range of adult and pediatric nonmelanoma rare malignancies. Continued tissue-agnostic drug development is warranted beyond the current BRAF plus MEK approved cancers.

Abstract INTRODUCTION: Oncogenic FGFR2 alterations (fusions/rearrangements, amplifications, mutations) are key drivers in cholangiocarcinoma (CCA) and multiple solid tumors. Current pan-FGFR inhibitor (FGFRi) therapy is limited by off-isoform toxicity and acquired FGFR2 kinase domain resistance mutations. RLY-4008 is a highly selective and potent oral inhibitor designed to target both FGFR2 driver and resistance mutations. We initiated a first-in-human study in advanced solid tumors patients (pts) to define the safety, pharmacokinetics (PK) and efficacy of RLY-4008 (NCT04526106). METHODS: Adult pts received RLY-4008 QD or BID on a 4-week cycle following a BOIN escalation design. Adverse events (AEs), PK, ctDNA and anti-tumor activity (RECIST 1.1) were assessed. RESULTS: As of 16AUG21, 45 pts (35 CCA; 10 other) have been treated with RLY-4008 at total daily doses of 30-200 mg (18 pts BID; 27 pts QD). 44 pts had oncogenic FGFR2 alterations (26 fusions/13 mutations/5 amplifications). The median number of prior anti-neoplastic therapies was 3 (range 1-15). 94% (33/35) of CCA pts had prior chemotherapy and 69% (24/35) had prior FGFRi. 56% (9/16) CCA pts with prior FGFRi and evaluable ctDNA had ≥1 FGFR2 resistance mutation at baseline, most commonly at positions 549 (8/9), 617 (3/9), or 564 (2/9). RLY-4008 had rapid absorption (Tmax 1-7h), half-life to support QD dosing (18-34 h), dose-dependent exposure (AUC; Cmax) and predicted FGFR2 occupancy &gt;85% across dose levels. The MTD has not been defined, and QD dose exploration continues to select the optimal biologically efficacious dose. AEs occurring in &gt;20% of pts include stomatitis (49%), palmar-plantar erythrodysesthesia (PPE, 38%), dry mouth (29%), and nail toxicities (22%), majority of which were ≤Gr 2. 6 pts had Gr 1-2 retinopathy, which resolved in all cases. 5 AEs were considered dose limiting toxicities: 4 in BID (rash/PPE/mucositis/hyperbilirubinemia) and 1 in QD (retinopathy). No Gr 4/5 drug-related AEs were seen. 25 pts remain on treatment (range 1-37 weeks). RLY-4008 showed broad anti-tumor activity across dose levels and FGFR2 alterations with radiographic tumor reductions of ≥10% in 59% pts (19/32; -11% to -83%). Activity was seen in FGFRi-naïve, FGFR2-fusion+ CCA with PRs in 50% of pts (3/6, 2 confirmed and 1 pending confirmation; -56% to -83%). Activity was also seen in FGFRi pre-treated FGFR2-fusion+ CCA pts (N=16) with 16 SD, including 9 pts with tumor reduction ≥10% (from -12% to -35%). Of the FGFRi pre-treated FGFR2-fusion+ CCA patients with detectable FGFR2 resistance mutations in ctDNA at baseline, 78% (7/9) were undetectable at C2D1. CONCLUSION: RLY-4008 demonstrates promising safety, tolerability, and clinical activity in FGFR2-altered solid tumor pts, including those who progressed on prior FGFRi therapy. Consistent with the FGFR2-selective mechanism, minimal off-isoform toxicity (FGFR1-hyperphosphatemia; FGFR4-diarrhea) was seen. These encouraging data validate selective targeting of FGFR2 and suggest that RLY-4008 has potential to overcome resistance to FGFRi. Citation Format: Lipika Goyal, Mitesh Borad, Vivek Subbiah, Amit Mahipal, Suneel Kamath, Kabir Mody, Robin Katie Kelley, Richard Kim, Vaibhav Sahai, Anthony El-Khoueiry, Efrat Dotan, Oleg Schmidt-Kittler, Jinshan Shen, Kai Yu Jen, Alicia Deary, Wei Guo, Mahesh Padval, Cori Ann J. Sherwin, Charles Ferte, Beni Wolf, Alison M. Schram. First results of RLY-4008, a potent and highly selective FGFR2 inhibitor in a first-in-human study in patients with FGFR2-altered cholangiocarcinoma and multiple solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P02-02.

AbstractActivating receptor-tyrosine kinase rearranged during transfection (RET) mutations and fusions are potent drivers of oncogenesis. The recent FDA approvals of highly potent and selective RET inhibitors, selpercatinib and pralsetinib, has altered the therapeutic management of RET aberrant tumors. There is ample evidence of the role of RET signaling in certain cancers. RET aberrations as fusions or mutations occur in multiple cancers, however, there is considerable phenotypic diversity. There is emerging data on the lack of responsiveness of immunotherapy in RET-altered cancers. Herein, we review the registrational data from the selective RET-inhibitor trials, and comprehensively explore RET alterations in pan-cancer adult malignancies and their co-alterations. These co-occuring alterations may define the future of RET inhibition from specific selective targeting to customized combination therapies as data are rapidly emerging on both on-target and off-target acquired resistance mechanisms. Fascinatingly, oncogenic RET fusions have been reported to mediate resistance to EGFR inhibition and KRASG12C inhibition.

Abstract Background: BRAF and MEK inhibitors are currently FDA approved for melanoma, non-small cell lung cancer, and anaplastic thyroid cancer. The lack of clinical benefit with BRAF inhibition in BRAF V600+ colorectal cancer (CRC) has prevented its tissue-agnostic drug development. However, updated results from Vemurafenib-Basket study (Cancer Discov. 2020 May;10(5):657-663 ) and the NCI-match trial ( J Clin Oncol. 2020 Nov 20;38(33):3895-3904) reveal that BRAF pathway inhibition is active in &gt; 20 unique cancer types. Objective: We aimed to describe the characteristics of BRAF V600 and study real-world outcomes using a clinico-genomic analysis using the AACR Genie database and the current medical literature. Methods: We reviewed the AACR GENIE database for the prevalence of BRAF V600 mutations across tumor types. We conducted a literature search (using PubMed from 2012-2019) for case reports of clinical response and outcomes in patients with BRAF V600 mutation-positive non-melanoma cancers who received BRAF inhibitor therapy. Results: Among 96,324 samples, BRAF V600 mutations were seen in 43 different tumor types across 2,963 samples (3.07 %) in the AACR GENIE database. BRAF V600 was most commonly present in thyroid cancer (40.9%), parathyroid cancer (31.8%), melanoma (26.1%), histiocytosis (25.7%), and head and neck NOS (14.3%). Literature review revealed total of 178 cases across 69 tumor types. The most common cases included Erdheim-Chester disease (n = 30, 16.9%), papillary thyroid carcinoma (n=16, 8.9%), anaplastic thyroid carcinoma (n = 13, 7.3%), and hairy cell leukemia (n = 13, 7.3%). Furthermore, dabrafenib (BRAF), dabrafenib/trametinib (BRAF+MEK), trametinib(MEK), vemurafenib (BRAF), vemurafenib/trametinib (BRAF+MEK), vemurafenib/cobimetinib (BRAF+MEK) were used in 34% (n =56), 16% (n = 27), 4% (n = 6), 44% (n = 72), 1% (n = 1), 2% (n =3), respectively. Overall, median PFS was 6.5 months, and median OS was 28.5 months with a median duration of response (DOR) of 8 months. Conclusion: BRAF V600 mutations are prevalent across multiple non-melanoma cancers, lead to oncogene addiction and are clinically actionable in a broad range of non-melanoma cancers. Continued drug development is warranted beyond the current BRAF+/- MEK approved cancers. Citation Format: Jacob J. Adashek, Aakash P. Desai, Arjun K. Menta, Jason Roszik, Vivek Subbiah. Pan-cancer efficacy of BRAF and/or MEK inhibitors in BRAF V600-mutant multiple non-melanoma cancers: A clinico-genomic study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1479.