A Phase I Study of KIN-3248, an Irreversible Small-molecule Pan-FGFR Inhibitor, in Patients with Advanced FGFR2/3-driven Solid Tumors

PURPOSE

Despite efficacy of approved FGFR inhibitors, emergence of polyclonal secondary mutations in the FGFR kinase domain leads to acquired resistance. KIN-3248 is a selective, irreversible, orally bioavailable, small-molecule inhibitor of FGFR1-4 that blocks both primary oncogenic and secondary kinase domain resistance FGFR alterations.

EXPERIMENTAL DESIGN

A first-in-human, phase I study of KIN-3248 was conducted in patients with advanced solid tumors harboring FGFR2 and/or FGFR3 gene alterations (NCT05242822). The primary objective was determination of MTD/recommended phase II dose (RP2D). Secondary and exploratory objectives included antitumor activity, pharmacokinetics, pharmacodynamics, and molecular response by circulating tumor DNA (ctDNA) clearance.

RESULTS

Fifty-four patients received doses ranging from 5 to 50 mg orally daily across six cohorts. Intrahepatic cholangiocarcinoma (48.1%), gastric (9.3%), and urothelial (7.4%) were the most common tumors. Tumors harbored FGFR2 (68.5%) or FGFR3 (31.5%) alterations-23 (42.6%) received prior FGFR inhibitors. One dose-limiting toxicity (hypersensitivity) occurred in cohort 1 (5 mg). Treatment-related, adverse events included hyperphosphatemia, diarrhea, and stomatitis. The MTD/RP2D was not established. Exposure was dose proportional and concordant with hyperphosphatemia. Five partial responses were observed; 4 in FGFR inhibitor naïve and 1 in FGFR pretreated patients. Pretreatment ctDNA profiling confirmed FGFR2/3 alterations in 63.3% of cases and clearance at cycle 2 associated with radiographic response.

CONCLUSION

The trial was terminated early for commercial considerations; therefore, RP2D was not established. Preliminary clinical data suggest that KIN-3248 is a safe, oral FGFR1-4 inhibitor with favorable pharmacokinetic parameters, though further dose escalation was required to nominate the MTD/RP2D.

SIGNIFICANCE

KIN-3248 was a rationally designed, next generation selective FGFR inhibitor, that was effective in interfering with both FGFR wild-type and mutant signaling. Clinical data indicate that KIN-3248 is safe with a signal of antitumor activity. Translational science support the mechanism of action in that serum phosphate was proportional with exposure, paired biopsies suggested phospho-ERK inhibition (a downstream target of FGFR2/3), and ctDNA clearance may act as a RECIST response surrogate.

First in human (FIH) phase 1/1b study evaluating KIN-3248, a next-generation, irreversible pan-FGFR inhibitor (FGFRi), in patients (pts) with advanced urothelial carcinoma (UC) and other solid tumors harboring FGFR2 and/or FGFR3 gene alterations

TPS593

Background: FGFR1-4 gene alterations are infrequent across solid tumors though preclinical and clinical evidence indicate activating alterations drive oncogenesis and tumor growth. They can be found in up to 20% of patients with UC and up to 35% of upper tract UC. Reversible FGFRi are approved for the treatment of pts with locally advanced or metastatic urothelial carcinoma (UC) with susceptible FGFR2 or FGFR3 genetic alterations (erdafitinib) or metastatic CCA harboring FGFR2 gene fusions or rearrangements (pemigatinib and infigratinib). A critical limitation of current clinical-stage FGFRi is the emergence of secondary, on-target resistance mutations (mutn) that reduce duration of response, and indeed, about 70% of CCA patients pre-treated with FGFRi exhibit secondary FGFR2 kinase domain resistance mutn at the time of relapse. KIN-3248 is a next-generation, selective, irreversible, small molecule pan-FGFRi, structurally designed to inhibit primary FGFR oncogenic alterations as well as secondary kinase domain mutn associated with disease progression. Preclinically, KIN-3248 has favorable pharmaceutical properties, is well-tolerated with continuous, daily oral administration in GLP toxicology studies and is efficacious against primary FGFR2 and FGFR3 oncogenic driver alterations as well as secondary FGFR2 resistance mutn (e.g., gatekeeper and molecular brake) in human cancer cell and PDX models. Methods: This is a FIH, multicenter, non-randomized Ph1 study of KIN-3248 in adult pts with advanced and metastatic solid tumors (AMST) harboring FGFR2 and/or FGFR3 gene alterations. KIN-3248 is given PO QD continuously in 28-day cycles until drug intolerance or disease progression. Part A is a dose-escalation assessing single agent KIN-3248 via a BOIN design to determine the MTD/RP2D. Part B will evaluate a selected dose of KIN-3248 in 3 cohorts of pts (UC, CCA, or other AMST), each driven by specified FGFR alterations—FGFRi-naïve and -pretreated pts are eligible in both parts. Enrollment criteria include ECOG PS 0-1, intact organ function, prior receipt of standard treatment or medical judgment that such is not appropriate. Pts may have measurable or evaluable disease. Key exclusion criteria include known active brain metastases and active/uncontrolled HBV/HCV. Planned sample size is ~120 pts. Primary endpoints are safety/tolerability (Part A), and preliminary antitumor activity: objective response rate, disease control rate, duration of response, & duration of stable disease (Part B). Secondary objectives include pharmacokinetic and pharmacodynamic assessments including measures of FGFR pathway modulation. The study is actively enrolling patients in the US and globally. Clinical trial information: NCT05242822 .

First in human (FIH) phase 1/1b study evaluating KIN-3248, a next-generation, irreversible pan-FGFR inhibitor (FGFRi), in patients (pts) with advanced cholangiocarcinoma (CCA) and other solid tumors harboring FGFR2 and/or FGFR3 gene alterations

TPS637

Background: FGFR1-4 gene alterations are infrequent across solid tumors though preclinical and clinical evidence indicate activating alterations drive oncogenesis and tumor growth. Pharmacological inhibition of FGFR1-4 leads to tumor shrinkage and disease control. Reversible FGFRi are approved for the treatment of pts with locally advanced or metastatic CCA harboring FGFR2 gene fusions or rearrangements (pemigatinib and infigratinib) or metastatic urothelial carcinoma (UC) with susceptible FGFR2 or FGFR3 genetic alterations (erdafitinib). A critical limitation of current clinical-stage FGFRi is the emergence of secondary, on-target resistance mutations (mutn) that reduce duration of response, and indeed, about 70% of CCA patients treated with either reversible or irreversible FGFRi exhibit secondary FGFR2 kinase domain resistance mutn at the time of relapse. KIN-3248 is a next-generation, selective, irreversible, small molecule pan-FGFRi, structurally designed to inhibit primary FGFR oncogenic alterations as well as secondary kinase domain mutn associated with disease progression. Preclinically, KIN-3248 has favorable pharmaceutical properties, is well-tolerated with continuous, daily oral administration in GLP toxicology studies and is efficacious against primary FGFR2 and FGFR3 oncogenic driver alterations as well as secondary FGFR2 resistance mutn (e.g., gatekeeper and molecular brake) in human cancer cell and PDX models. Methods: This is a FIH, multicenter, non-randomized Ph1 study of KIN-3248 in adult pts with advanced and metastatic solid tumors (AMST) harboring FGFR2 and/or FGFR3 gene alterations. KIN-3248 is given PO QD continuously in 28-day cycles until drug intolerance or disease progression. Part A is a dose-escalation assessing single agent KIN-3248 via a BOIN design to determine the MTD/RP2D; Part B will evaluate a selected dose of KIN-3248 in 3 cohorts of pts (CCA, UC, or other AMST), each driven by specified FGFR alterations—FGFRi-naïve and -pretreated pts are eligible in both parts. Enrollment criteria include ECOG PS 0-1, intact organ function, prior receipt of standard treatment or medical judgment that such is not appropriate. Pts may have measurable or evaluable disease. Key exclusion criteria include known active brain metastases and active/uncontrolled HBV/HCV. Planned sample size is ~120 pts. Primary endpoints are safety/tolerability (Part A), and preliminary antitumor activity: objective response rate, disease control rate, duration of response, and duration of stable disease (Part B). Secondary objectives include pharmacokinetic and pharmacodynamic assessments including measures of FGFR pathway modulation. The study is actively enrolling patients in the US and globally. Clinical trial information: NCT05242822 .

A phase 1b study (STELLAR-002) of XL092 administered in combination with nivolumab (NIVO) with or without ipilimumab (IPI) or bempegaldesleukin (BEMPEG) in patients (pts) with advanced solid tumors

TPS4600

Background: XL092 is a novel oral inhibitor of receptor tyrosine kinases, including MET, VEGFR2, and TAM kinases (AXL, MER), which are implicated in tumor growth, metastasis, angiogenesis, and immune suppression of the tumor microenvironment. XL092 has a relatively short half-life (̃21h) to support convenient daily dosing and help manage tolerability. Preclinical studies of XL092 with an anti‒PD-1 immune checkpoint inhibitor (ICI) demonstrated antitumor activity in tumor models, and BEMPEG (IL-2 pathway agonist) showed synergy with anti‒PD-L1 and anti‒CTLA-4 agents. This phase 1b trial will evaluate the safety and clinical activity of XL092 alone and in combination with NIVO (anti‒PD-1 mAb) ±IPI (anti‒CTLA-4 mAb) or ±BEMPEG in pts with advanced solid tumors including genitourinary cancers. Presented here is the study design. Methods: This multicenter phase 1b, open-label study (NCT05176483) will enroll pts with unresectable advanced or metastatic solid tumors in dose-escalation and expansion stages. In the dose-escalation stage, ̃36 pts will be enrolled in three XL092 combination therapy cohorts using a rolling 6 design. Cohort A: XL092 (starting dose [SD] 100 mg PO QD) + NIVO (360 mg IV Q3W); Cohort B: XL092 (SD 80 mg PO QD) + NIVO (3 mg/kg IV Q3W × 4, then 480 mg IV Q4W) + IPI (1 mg/kg Q3W × 4); Cohort C: XL092 (SD 100 mg PO QD) + NIVO (360 mg IV Q3W) + BEMPEG (0.006 mg/kg IV Q3W). The primary objective of the dose-escalation stage is to determine the recommended doses of XL092 with the NIVO regimens to be used in the expansion stage. The expansion stage will include cohorts of advanced genitourinary tumors: Cohort 1, clear-cell renal cell carcinoma (ccRCC), no prior systemic therapy; Cohort 2, ccRCC, 1 prior ICI combination regimen; Cohort 3, metastatic castration-resistant prostate cancer (mCRPC), 1 prior novel-hormonal therapy; Cohort 4, urothelial carcinoma (UC), 1 prior platinum-based regimen, ICI-naïve; Cohort 5, UC, ≤2 prior systemic regimens, ICI-experienced; Cohort 6, non-ccRCC, no prior systemic therapy. In each cohort, pts will be randomized to one of the following treatments (based on tumor cohort): single-agent XL092 (Cohorts 2‒6); XL092+NIVO (Cohorts 1‒6); NIVO+IPI (Cohort 1); XL092+NIVO+IPI (Cohorts 1, 3, 6); NIVO+BEMPEG (Cohort 1), XL092+NIVO+BEMPEG (Cohort 1, 2, 4‒6). Thirty pts will be enrolled in each single-agent XL092 arm and 40 pts in each combination therapy arm. Expansion stage objectives are to assess preliminary efficacy, safety, and pharmacokinetics of XL092 alone or in combination in each tumor-specific cohort. Primary efficacy endpoints include objective response rate by investigator per RECIST v1.1 and progression-free survival by blinded independent radiology committee per Prostate Working Group 3 criteria (mCRPC cohort only). The study is currently enrolling pts. Clinical trial information: NCT05176483.

Design and rationale of a first-in-human (FIH) phase 1/1b study evaluating KIN-3248, a next-generation, irreversible (irrev), pan-FGFR inhibitor (FGFRi), in adult patients with solid tumors harboring FGFR2 and/or FGFR3 gene alterations (NCT05242822)

TPS9601

Background: FGFR1-4 gene alterations are observed in approximately 7% of all human cancers. There are currently 3 FDA-approved, reversible FGFRi for treatment of patients w/previously treated, locally advanced or metastatic (met) cholangiocarcinoma (CCA) harboring FGFR2 gene fusions/rearrangements (pemigatinib and infigratinib) or met urothelial carcinoma (UC) w/susceptible FGFR2 or FGFR3 genetic alterations (erdafitinib). A major limitation of approved and clinical-stage FGFRi is emergence of secondary, on-target resistance mutations (mutn) that reduce duration of response. Up to 67% of CCA patients treated with either reversible or irrev FGFRi exhibit secondary FGFR2 kinase domain resistance mutn at the time of relapse. KIN-3248 is a next-generation, selective, irrev, small molecule pan-FGFRi, structurally designed to inhibit primary FGFR oncogenic alterations as well as secondary kinase domain mutn associated w/disease progression. Preclinically, KIN-3248 has favorable pharmaceutical properties, is well-tolerated with continuous, daily oral administration in 28d GLP toxicology studies in rats and beagle dogs and is efficacious against primary FGFR2 and FGFR3 oncogenic driver alterations as well as secondary FGFR2 resistance mutn (e.g., gatekeeper and molecular brake) in human cancer cell and PDX models in vitro and in vivo. Methods: This is a FIH, multicenter, non-randomized Ph1 study of KIN-3248 in adult pts with advanced & metastatic solid tumors (AMST) harboring FGFR2 and/or FGFR3 gene alterations. KIN-3248 is given po qd continuously in 28-day cycles until drug intolerance or disease progression. Planned sample size is approx. 120 pts: Part A is a dose-escalation to MTD for pts w/AMST having either FGFR2 and/or FGFR3 alterations. Part A assesses single agent KIN-3248; Part B will evaluate a selected dose of KIN-3248 in 3 cohorts of pts (ICC, UC, or other AMST), each driven by specified FGFR alterations. Standard Ph1 enrollment criteria are required (ECOG PS 0-1, normal organ function, prior receipt of standard treatment or medical judgment that such is not appropriate). Pts may have measurable or evaluable disease. Key exclusion criteria include known active brain metastases and active/uncontrolled HBV/HCV. FGFRi-naïve & -pretreated patients are both eligible. Primary endpoints are safety/tolerability (Part A), and preliminary antitumor activity: objective response rate, disease control rate, duration of response, & duration of stable disease (Part B). Secondary objectives include pharmacokinetic and pharmacodynamic assessments including measures of FGFR pathway modulation. Enrollment is expected to commence in April 2022. Clinical trial information: NCT05242822.

Clinical and Molecular Characterization of POLE Mutations as Predictive Biomarkers of Response to Immune Checkpoint Inhibitors in Advanced Cancers

PURPOSE

DNA polymerase epsilon is critical to DNA proofreading and replication. Mutations in POLE have been associated with hypermutated tumors and antitumor response to immune checkpoint inhibitor (ICI) therapy. We present a clinicopathologic analysis of patients with advanced cancers harboring POLE mutations, the pattern of co-occurring mutations, and their response to ICI therapy within the context of mutation pathogenicity.

METHODS

We conducted a retrospective analysis of next-generation sequencing data at MD Anderson Cancer Center to identify patient tumors with POLE mutations and their co-occurring mutations. The pathogenicity of each mutation was annotated using InterVar and ClinVar. Differences in therapeutic response to ICI, survival, and co-occurring mutations were reported by POLE pathogenicity status.

RESULTS

Four hundred fifty-eight patient tumors with POLE mutations were identified from 14,229 next-generation sequencing reports; 15.0% of POLE mutations were pathogenic, 15.9% benign, and 69.1% variant of unknown significance. Eighty-two patients received either programmed death 1 or programmed death ligand-1 inhibitors as monotherapy or in combination with cytotoxic T-cell lymphocyte-4 inhibitors. Patients with pathogenic POLE mutations had improved clinical benefit rate (82.4% v 30.0%; P = .013), median progression-free survival (15.1 v 2.2 months; P < .001), overall survival (29.5 v 6.8 months; P < .001), and longer treatment duration (median 15.5 v 2.5 months; P < .001) compared to those with benign variants. Progression-free survival and overall survival remained superior when adjusting for number of co-occurring mutations (≥ 10 v < 10) and/or microsatellite instability status (proficient mismatch repair v deficient mismatch repair). The number of comutations was not associated with response to ICI (clinical benefit v progressive disease: median 13 v 11 comutations; P = .18).

CONCLUSION

Pathogenic POLE mutations were associated with clinical benefit to ICI therapy. Further studies are warranted to validate POLE mutation as a predictive biomarker of ICI therapy.

All bone metastases are not created equal: Revisiting treatment resistance in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common malignancy of the kidney, representing 80-90% of renal neoplasms, and is associated with a five-year overall survival rate of approximately 74%. The second most common site of metastasis is bone. As patients are living longer due to new RCC targeting agents and immunotherapy, RCC bone metastases (RCCBM) treatment failure is more prevalent. Bone metastasis formation in RCC is indicative of a more aggressive disease and worse prognosis. Osteolysis is a prominent feature and causes SRE, including pathologic fractures. Bone metastasis from other tumors such as lung, breast, and prostate cancer, are more effectively treated with bisphosphonates and denosumab, thereby decreasing the need for palliative surgical intervention. Resistance to these antiresportives in RCCBM reflects unique cellular and molecular mechanisms in the bone microenvironment that promote progression via inhibition of the anabolic reparative response. Identification of critical mechanisms underlying RCCBM induced anabolic impairment could provide needed insight into how to improve treatment outcomes for patients with RCCBM, with the goals of minimizing progression that necessitates palliative surgery and improving survival.

Bone-targeted therapy in patients with renal cell carcinoma bone metastases undergoing palliative surgery

e16572

Background: RCC bone metastases (RCCBM) are found in 20-39% of patients and are becoming more prevalent. RCCBM cause significant morbidity and often require surgical intervention. Current bone-targeted therapies include bisphosphonates and denosumab. Previous literature has suggested that bisphosphonates do not improve survival or reduce skeletal related events and little has been published about the effect of denosumab. Here we present experience describing outcomes and therapeutic effect in patients with RCCBM following palliative surgery for bone metastasis. Methods: We performed a retrospective analysis of 226 patients with RCCBM who underwent orthopedic surgery at MD Anderson Cancer Center between 11/2005 – 8/2019. The Kaplan-Meier method and log-rank test were used to estimate and evaluate survival differences. Results: Patient characteristics included: median age 58.2, male 66.4%, clear cell histology 93.5%, metastatic at presentation 57.9%, nephrectomy 79.8% (63.9% prior to orthopedic intervention), received radiation to the surgical site (pre-op: 13.0%, post-op: 41.4%). First orthopedic intervention: resection arthroplasty 37.2%, curettage and intramedullary nailing (IMN) 18.6%, IMN 16.4%, open reduction internal fixation 15.0%, amputation 2.7%, 10.2% other. Pre-op therapy: bisphosphonate 12.4%, denosumab 5.8%, both 2.7%, none 79.2%. Post-op therapy: bisphosphonate 18.1%, denosumab 13.7%, both 0.9%, none 67.2%. With a median follow up of 3.1 years after first orthopedic intervention, median overall survival (OS) was 2.7 yr (95% CI 2.1 – 3.6). Progression free survival (PFS) was calculated from time of first surgery to either first progression or death; median PFS was 5.2 months (95% CI 4.6 – 7.5). Pre-op or post-op bone-targeted therapy was not significantly associated with PFS (yes vs no: Pre-op: median 3.4 vs 6.3 mth, p=0.42; Post-op: median 4.3 vs 5.8 mth, p=0.61) or OS (Pre-op: 2.1 vs 2.9 yr, p=0.45; Post-op: 2.4 vs 3.2 yr, p=0.18). Post-op denosumab compared to bisphosphonate was associated with increased PFS (9.6 vs 3.8 mth, p=0.03) and OS (3.3 vs 1.6 yr, p=0.02). However, post-op denosumab vs no bone-targeted therapy was not significantly associated with increased PFS (9.6 vs 5.8 mth, p=0.42) or OS (3.3 vs 3.2 yr, p=0.85). Of note, post-op bisphosphonate vs no bone-targeted therapy was associated with reduced PFS (3.8 vs 5.8 mth, p=0.04) and OS (1.6 vs 3.2 yr, p=0.01). Conclusion: Addition of bone-targeted therapy did not significantly improve PFS or OS in patients with RCCBM undergoing orthopedic intervention. Post-op denosumab was associated with better PFS and OS compared to bisphosphonates and bisphosphonates were associated with worse PFS and OS compared to no bone-targeted therapy. Patient selection for therapy may be an important source of bias. Prospective research is needed to clarify the role and selection of bone-targeted therapy in RCCBM patients.

PMC: A more precise classifier of POLE mutations to identify candidates for immune therapy

3548

Background: Specific somatic mutations in DNA polymerase epsilon ( POLE) can cause a hypermutant phenotype with tumor mutation burden (TMB) in excess of 100 mutations per megabase. It has been reported that POLE mutant tumors are enriched in response to immune therapy and this association is being tested in multiple active clinical trials. However, most POLE mutations are passenger mutations and have no pathogenic role. Current methods to classify POLE mutations are limited in both accuracy and completeness, which could lead to inappropriate use of immune agents in tumor such as MSS CRC, where response rate is 5% or less. Here we present a new classifier, POLE Mutation Classifier or PMC, based on the unique trinucleotide mutation signature caused by selective loss of the proofreading function (LOP) of POLE. Methods: cBioPortal was queried to identify all tumors with POLE mutation. TMB was calculated for each, additionally, trinucleotide mutation signatures were obtained for all POLE mutant tumors in TCGA. Using OncoKB to identify a gold standard of 12 functional POLE mutations (n = 98 tumors) a POLE mutational signature was created. A combination of mutational signature, amino acid location, and TMB was used to classify each POLE variant. Results: Among all 48035 unique tumors the overall frequency of POLE mutations was 2.5% (n = 1184), however only 9.2% (n = 110) were determined to cause the selective LOP. The incidence of LOP POLE mutation was highest in uterine carcinoma and CRC, these tumors also had the highest ratio of LOP to passenger mutations. In a pan-cancer analysis the overall survival of LOP POLE patients was significantly better than those with passenger mutations (not-yet-reached vs. 51 mo, HR = 4.4, p < 0.0001). A similar analysis performed using the polyphen-2 classifier to identify functional POLE mutations did not show a difference in overall survival (HR = 1.0, p-value = 0.57). To further validate the improved specificity of the PMC classifier TMB was used as a surrogate marker, using the PMC classifier 98% of tumors with LOP showed hypermutation (TMB > 20mut/Mb), vs. 53% called functional by polyphen-2. A retrospective analysis of MD Anderson CRC patients identified 25 patients with LOP POLE mutation, who had improved OS relative to 267 CRC patients with passenger POLE mutation (not-yet-reached vs. 70 mo, HR:4.2, p = 0.028). Four metastatic CRC patients with LOP POLE mutation were treated with immune therapy (nivolumab, or ipilimumab/nivolumab) in 2nd or 3rd line, all four achieved objective response and remain on therapy (mean time on treatment 15 mo). Conclusions: The PMC classifier specifically identifies mutations in POLE that cause loss of the proofreading function, outperforming both manually curated databases and machine learning-based methods. Clinical trials that use POLE mutation as a selection criteria for immune therapy should be restricted to just those POLE mutations that cause LOP.

Combination antiangiogenic tyrosine kinase inhibition and anti-PD1 immunotherapy in metastatic renal cell carcinoma: A retrospective analysis of safety, tolerance, and clinical outcomes

INTRODUCTION

Two separate antiangiogenic tyrosine kinase inhibitors (TKIs) and immunotherapy (IO) combinations are FDA-approved as front-line treatment for metastatic renal cell carcinoma (mRCC). Little is known about off-protocol and post-front-line experience with combination TKI-IO approaches.

METHODS

We conducted a retrospective analysis of mRCC patients who received combination TKI-IO post-first-line therapy between November 2015 and January 2019 at MD Anderson Cancer Center and Duke Cancer Institute. Chart review detailed patient characteristics, treatments, toxicity, and survival. Independent radiologists, blinded to clinical data, assessed best radiographic response using RECIST v1.1.

RESULTS

We identified 48 mRCC patients for inclusion: median age 65 years, 75.0% clear cell histology, 68.8% IMDC intermediate risk, and median two prior systemic therapies. TKI-IO combinations included nivolumab-cabozantinib (N +C; 24 patients), nivolumab-pazopanib (N+P; 13), nivolumab-axitinib (6), nivolumab-lenvatinib (2), and nivolumab-ipilimumab-cabozantinib (3). The median progression-free survival was 11.6 months and the median overall survival was not reached. Response data were available in 45 patients: complete response (CR; n = 3, 6.7%), partial response (PR; 20, 44.4%), stable disease (SD; 19, 42.2%), and progressive disease (3, 6.7%). Overall response rate was 51% and disease control rate (CR+PR+SD) was 93%. Only one patient had a grade ≥3 adverse event.

CONCLUSION

To our knowledge, this is the first case series reporting off-label use of combination TKI-IO for mRCC. TKI-IO combinations, particularly N+P and N+C, are well tolerated and efficacious. Although further prospective research is essential, slow disease progression on IO or TKI monotherapy may be safely controlled with addition of either TKI or IO.

Combination therapy with nivolumab and tyrosine kinase inhibitors in patients with metastatic renal cell carcinoma

e17090

Background: Two immunotherapy (IO) and tyrosine kinase inhibitor (TKI) combinations are FDA-approved for patients (pts) with metastatic renal cell carcinoma (mRCC). Here we present a multicenter off-protocol experience with IO/TKI combinations after progression on monotherapy. Methods: We performed a retrospective analysis of pts with mRCC who received combination non-FDA approved off-protocol IO/TKI combination therapy from 11/2015 – 1/2019 at MD Anderson Cancer Center and Duke Cancer Institute. Results: 48 pts met criteria for study inclusion. At therapy start: median (med) age 65 years; 75% clear cell histology; 68.8% IMDC intermediate risk (20.8% favorable, 10.4% poor); 81.3% prior nephrectomy; med metastatic sites: 2; med prior systemic treatments: 2; most common metastatic sites: lung (58.3%), lymph node (52.1%), and bone (43.8%). Pts received nivolumab (nivo) in combination with the following: cabozantinib (n = 24, 50%), pazopanib (13, 27.1%), axitinib (6, 12.5%), lenvatinib (2, 4.2%), ipilimumab/cabozantinib (3, 6.3%). Med PFS was 13.7 months and med OS was not reached. The two largest cohorts received nivo + cabozantinib (N+C; med dose 40 mg daily) or nivo + pazopanib (N+P; med dose 400 mg daily). The N+C cohort had higher med metastatic sites (3 vs 2) and was more pretreated with agents unique to their IO/TKI combination (med 2 vs 0). In the N+P group, more pts had started on TKI prior to addition of nivo at progression (69.2% vs 45.8%), and fewer had IO monotherapy with TKI addition (30.8% vs 50%). With a med follow up of 14.0 months after combination start, the N+C cohort had a med PFS of 7.3 months (initiated TKI first: 4.8, IO first: 8.2) and med OS of 18.2 months (TKI first: 11.8, IO first: 24.3). The N+P cohort had med follow up of 20.5 months after combination, med PFS of 21.3 months (TKI first: 16.5, IO first: 21.8), and med OS was not reached. In the N+C group, 87.5% experienced any grade adverse event (AE), most common included fatigue (79.2%), diarrhea (42.7%), nausea (29.2%), hypertension (29.2%), and weight loss (25.0%). In the N+P group, 92.3% experienced any grade AE, including fatigue (76.9%), hypertension (38.5%), diarrhea (30.8%), nausea (30.8%), and weight loss (30.8%). There were no grade ≥3 AEs. Conclusions: Slow disease progression on nivo or TKI may be safely controlled with addition of IO/TKI therapy. Med PFS after addition of nivo to TKI appears similar (N+C) and improved (N+P) compared to nivo monotherapy (Checkmate-025). Med PFS after addition of TKI to IO was also similar (N+C) and improved (N+P) compared to historical controls.

Correlation of pathogenic POLE mutations with clinical benefit to immune checkpoint inhibitor therapy

3008

Background: Mutations in DNA polymerase epsilon ( POLE) may induce DNA replication errors, increasing neoantigen load and potentially enhancing clinical benefit to immune checkpoint inhibitors (ICI). We present a clinicopathologic analysis of patients (pts) with advanced cancers harboring POLE mutations and their response to ICI therapy at MD Anderson Cancer Center. Methods: We used targeted exome sequencing via CLIA-certified next generation sequencing assays to identify pts with POLE-aberrant tumors and their co-occurring mutations. The pathogenicity of each POLE mutation was annotated utilizing InterVar and ClinVar databases. Chi-square analysis was performed. Results: Tumors from 12,947 pts were analyzed and 448 (3.5%) pts had a mutation or copy number variation in POLE (3.5%), comparable to the TCGA PanCancer Atlas (4.0%). Clinical data were available for 293 pts; the most common cancers were colorectal (14.7%), non-small cell lung (13.7%), cholangiocarcinoma (13.3%) and melanoma (10.2%). There were 267 unique co-mutations, including KRAS (23.0%), ARID1A (21.5%), BRCA2 (18.7%), ATM (18.4%), CDKN2A (17.5%), BRAF (15.3%), EGFR (15.3%), ATRX (12.6%), CREBBP (11.7%), APC (11.3%), ATR (11.0%), BRCA1 (11.0%) and CDK12 (10.4%). POLE variants were annotated in all pts: pathogenic/likely pathogenic (n = 34, 11.6%), benign/likely benign (61, 20.8%), and variant of unknown significance (198, 67.6%). 104 (35.8%) of 293 pts with POLE mutations received PD-1/L1 inhibitors as monotherapy or in combination. 93 (88.4%) of 104 pts were evaluable for response: Radiological CR 4.3% (n = 4), PR 26.9% (n = 25), SD 22.6% (n = 21), PD 46.2% (n = 43), for a clinical benefit rate (CR + PR + SD) of 53.8%. Pathogenic status of POLE mutation was associated with clinical benefit to PD-1/L1 inhibitors (p = 0.04). TMB (p = 0.44), PD-L1 (p = 0.11), and MSI (p = 0.66) status were not associated with pathogenic status. MSI-H status was not over-represented in pts with ICI clinical benefit (p = 0.36). Conclusions: Pathogenic POLE mutations were associated with clinical benefit to ICI therapy. Further studies are warranted to validate POLE mutations as a predictive biomarker. Multiple co-occurring DNA damage response mutations were found, which may contribute to ICI clinical benefit.

Identifying functional loss of ATM gene in patients with advanced cancer

3629

Background: ATM is frequently mutated in cancer, and defects may serve as a putative predictive biomarker. However, the functional impact of most ATM variants is not well known. In this study, we examined the relationship between ATM variants and ATM protein expression to better discern ATM functional defects in patients (pts) with advanced cancer. Methods: We retrospectively identified pts seen at MD Anderson Cancer Center who had ATM variants detected on CLIA-certified next generation sequencing (NGS) assays. ATM immunohistochemistry (IHC) was performed on available tumors. We then prospectively assessed ATM IHC on tumors from pts who were referred for DNA damage repair inhibitor (DDRi) trials. Functional classification of the variants was performed via published in silico tools and/or precision oncology decision support (PODS). An IHC cut-off of 100% loss in tumor cell nuclei defined ATM loss of protein (LOP). Results: Of 1394 ATM-mutant tumors identified retrospectively, ATM alterations were classified as 16% (N = 216) inactivating, 12% (N = 163) potentially inactivating, 71% (N = 993) variant of unknown significance (VUS), and 2% (N = 22) benign. Coding variants were seen across the ATM exonic structure/splice sites, and 20 individual variants were shared in > 10 pts. 263/297 available retrospective tumor samples had interpretable IHC results; 27% (N = 72) had ATM LOP. LOP was most prevalent in tumors with inactivating ATM variants (39/100, 39%); but, importantly, LOP was seen in 20% (N = 33/162) of potentially inactivating/VUS, thus better clarifying their functional impact. In the prospective cohort of 217 pt tumors, 17% (N = 37) had ATM LOP. 29% (N = 62/217) of this cohort also had ATM variants. ATM LOP was seen in 48% of tumors with inactivating variants (N = 14/29), 25% of tumors with potentially/VUS(N = 9/36), and 9% (N = 14/156) of tumors without ATM variants identified. ATM LOP was detected most commonly in colorectal (24%; N = 8/34), cholangiocarcinoma (20%; N = 6/30), prostate (16%; N = 16/104) and pancreatic (9%; N = 1/11) cancers among this cohort of pts referred for DDRi trials. Conclusions: ATM coding variants occurred across the gene, with certain variants shared across tumor types. The functional impact of most ATM variants was VUS, and ATM LOP can help clarify function in up to 25% of these VUS. Also, ATM LOP can be seen even in tumors without ATM variants identified, suggesting epigenetic or post-translational loss. Future prospective studies assessing predictive capability of paired DNA and protein-level profiling of ATM are warranted.

A provider's guide to primary myelofibrosis: pathophysiology, diagnosis, and management

Although understanding of the pathogenesis and molecular biology of primary myelofibrosis continues to improve, treatment options are limited, and several biological features remain unexplained. With an appropriate clinical history, exam, laboratory evaluation, and bone marrow biopsy, the diagnosis can often be established. Recent studies have better characterized prognostic factors and driver mutations in myelofibrosis, facilitated by use of next-generation sequencing. These advances have facilitated development of a management strategy that is based on both risk factors and clinical phenotype. For low-risk patients, treatment will depend on symptom severity. For patients with higher-risk disease, several treatments are available including JAK inhibitors, allogeneic hematopoietic stem cell transplant, and clinical trials using novel molecularly targeted therapies and rational drug combinations. In this review, we outline what is known about the disease pathogenesis, discuss an approach to reaching the diagnosis, review the prognosis of myelofibrosis, and detail current therapeutic strategies.

The oncology prognosis and informed consent: Presentation of a new model to best inform patients

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Background: Receiving a malignant diagnosis is challenging and patients must be properly informed of their prognosis to make the best decisions for themselves and their families. The general population has a low degree of statistical literacy and therefore approximations should be considered favorable. However, given that half of patients desire quantitative data, physicians must provide this information within a context that is relevant and comprehensible. Single-point median survival data is less meaningful for patient decision-making. What is preferable is that physicians give experience-based estimations on how a patient might compare to the ‘average’. Including this information leads to more informed consent and best follows the ethical principle of autonomy. Methods: This is a novel framework for providing a prognosis that builds upon the multiples-of-the-mean model established in 2010 by Kiely, Tattersall, and Stockler. This framework was derived from original ethics research involving patient preferences, statistical comprehension, healthcare communication, and medical decision-making. Results: Graphical representation of Kiely’s model provides an intelligible view of quantitative data and allows for the physician to include an experience-based estimation. Steps: (1) Draw a Horizontal line, (2) Calculate from median survival data by using five multiples: 0.25 (Worst-Case, 10% of patients), 0.5 (Lower-Typical, 25%), 1 (Median, 50%), 2 (Upper-Typical, 75%), and 3 (Best-Case, 90%), (3) Label the chart using simple time points in months or years (4) Draw a circle over the region that best represents the patient’s expectation, (5) Provide the diagram alongside easy-to-understand language that clarifies the meaning of the numerical data with written likelihood of the occurrence, such as “almost no chance”, “not likely”, “even chances”, “likely”, and “fairly confident”. Conclusions: Kiely’s model has proven an accurate estimation in colorectal, castration-resistant prostate, non-small-cell lung, and metastatic breast cancer. A graphical representation should provide physicians an easy tool to strengthen informed consent and better aid their patients in decision-making.

The oncology prognosis and informed consent: Presentation of a new model to best inform patients

146

Background: Receiving a malignant diagnosis is challenging and patients must be properly informed of their prognosis to make the best decisions for themselves and their families. The general population has a low degree of statistical literacy and therefore approximations should be considered favorable. However, given that half of patients desire quantitative data, physicians must provide this information within a context that is relevant and comprehensible. Single-point median survival data is less meaningful for patient decision-making. What is preferable is that physicians give experience-based estimations on how a patient might compare to the ‘average’. Including this information leads to more informed consent and best follows the ethical principle of autonomy. Methods: This is a novel framework for providing a prognosis that builds upon the multiples-of-the-mean model established in 2010 by Kiely, Tattersall, and Stockler. This framework was derived from original ethics research involving patient preferences, statistical comprehension, healthcare communication, and medical decision-making. Results: Graphical representation of Kiely’s model provides an intelligible view of quantitative data and allows for the physician to include an experience-based estimation. Steps: (1) Draw a Horizontal line, (2) Calculate from median survival data by using five multiples: 0.25 (Worst-Case, 10% of patients), 0.5 (Lower-Typical, 25%), 1 (Median, 50%), 2 (Upper-Typical, 75%), and 3 (Best-Case, 90%), (3) Label the chart using simple time points in months or years (4) Draw a circle over the region that best represents the patient’s expectation, (5) Provide the diagram alongside easy-to-understand language that clarifies the meaning of the numerical data with written likelihood of the occurrence, such as “almost no chance”, “not likely”, “even chances”, “likely”, and “fairly confident”. Conclusions: Kiely’s model has proven an accurate estimation in colorectal, castration-resistant prostate, non-small-cell lung, and metastatic breast cancer. A graphical representation should provide physicians an easy tool to strengthen informed consent and better aid their patients in decision-making.

Differentiating skin-limited and multisystem Langerhans cell histiocytosis

OBJECTIVE

To identify features associated with multisystem involvement and therapeutic failure in patients with skin Langerhans cell histiocytosis (LCH).

STUDY DESIGN

We reviewed medical records of 71 consecutive patients with LCH with skin involvement evaluated at Texas Children's Hospital and analyzed clinical features, laboratory results, and the presence of circulating cells with the BRAF-V600E mutation with respect to initial staging and clinical outcomes.

RESULTS

Skin disease in patients older than 18 months of age at diagnosis was associated with the presence of multisystem disease (OR, 9.65; 95% CI, 1.17-79.4). Forty percent of patients referred for presumed skin-limited LCH had underlying multisystem involvement, one-half of these with risk-organ involvement. Patients with skin-limited LCH had a 3-year progression-free survival of 89% after initial therapy, and none developed multisystem disease. Patients with skin/multisystem involvement had a 3-year progression-free survival of 44% with vinblastine/prednisone therapy, and risk-organ involvement did not correlate with failure to achieve nonactive disease. Circulating cells with BRAF-V600E were detected at higher frequency in patients with multisystem involvement (8 of 11 skin/multisystem vs 1 of 13 skin-limited; P = .002).

CONCLUSION

Skin-limited LCH necessitates infrequent therapeutic intervention and has a lower risk of progression relative to skin plus multisystem LCH. The less-aggressive clinical course and lack of circulating cells with the BRAF-V600E mutation in skin-limited LCH suggest a different mechanism of disease origin compared with multisystem or risk-organ disease.

Choosing treatment for stage I seminoma: who should get what?

We agree that physicians should choose active surveillance for their patients if they have the means to afford health insurance and are relatively stable within their careers. Prophylactic radiotherapy should be offered to patients who need a relaxed follow-up schedule for financial, emotional, or compliance reasons. For adjuvant carboplatin, longer follow-up data are needed to better define survival, long-term toxicities, frequency of second primary testicular cancers, quality of life, and cost to the healthcare system.