Erdafitinib in pediatric patients with advanced solid tumors with fibroblast growth factor receptor (FGFR) gene alterations: RAGNAR study pediatric cohort

TPS10058

Background: FGFR gene alterations have been observed in pediatric patients with cancers and represent potentially targetable genomic variants. Gliomas (high- and low-grade) and soft tissue sarcomas are among the pediatric solid tumors that may harbor FGFR alterations. Erdafitinib is a selective pan-FGFR inhibitor approved in patients with locally advanced or metastatic urothelial carcinoma with susceptible FGFR2/3 alterations. RAGNAR (NCT04083976) is an ongoing single-arm, open-label, phase 2 histology-agnostic study investigating the efficacy and safety of erdafitinib in patients with advanced solid tumors exhibiting FGFR alterations after failure of standard systemic therapies. Here we describe the pediatric study cohort. Methods: The pediatric cohort (n = 26, planned) includes patients (≥ 6- < 18 y) with advanced solid tumors (measurable disease per RECIST v.1.1 or RANO [brain tumors]) with FGFR mutations, gene fusions, or internal tandem duplication (patients with FGFR amplification are not eligible) identified via local test reports or central molecular testing. Eligible patients will have received ≥ 1 lines of prior systemic therapy, have exhausted or be unable to tolerate standard-of-care therapies, and have documented disease progression and measurable disease. In addition, up to 6 patients in this cohort will be allowed to be treatment naive. Children and adolescents will be treated with oral erdafitinib, allowing pharmacodynamically guided uptitration based on serum phosphate levels to maximize efficacy. Treatment will continue until progressive disease. The primary end point is overall response rate (ORR) assessed by an independent review committee. Secondary efficacy end points include ORR assessed by the investigator, duration of response, disease control rate, clinical benefit rate, progression-free survival, and overall survival. Other secondary end points are pharmacokinetic exposure parameters, incidence/severity of adverse events, and change from baseline in patient-reported health status. End-of-treatment visit will occur 30 days after the last dose of erdafitinib. A follow-up phase will continue until death, withdrawal of consent, loss to follow-up, or end of study. As of January 2022, 3 patients have been enrolled. Clinical trial information: NCT04083976.

Tumor agnostic efficacy and safety of erdafitinib in patients (pts) with advanced solid tumors with prespecified fibroblast growth factor receptor alterations (FGFRalt) in RAGNAR: Interim analysis (IA) results

3007

Background: Erdafitinib (erda) is an oral selective pan-FGFR tyrosine kinase inhibitor approved to treat locally advanced or metastatic urothelial carcinoma (UC) in adults with susceptible FGFR3/2alt who have progressed during or after ≥ 1 line of platinum containing chemotherapy . FGFRalt are observed across a wide range of malignancies and may function as oncogenic drivers independent of the underlying tumor type. RAGNAR (NCT04083976) is an ongoing phase 2 open label, single arm tumor agnostic trial investigating the efficacy and safety of erda in pretreated adult and pediatric pts with advanced solid tumors and FGFRalt. Here, we report results from a planned IA of RAGNAR. Methods: Pts aged ≥ 6 y with advanced or metastatic solid tumors of any histology (except UC) with predefined FGFR1-4alt (mutations/fusions based on local/central test) and documented disease progression on ≥ 1 prior line of systemic therapy (tx) and no alternative standard tx received oral erda until disease progression or intolerable toxicity. The primary end point is objective response rate (ORR) by independent review committee (IRC). Secondary end points include investigator assessed ORR, duration of response (DOR), disease control rate (DCR), clinical benefit rate (CBR), PFS, OS, and treatment emergent adverse events (TEAEs). Results: As of the IA data cutoff, 178 pts were treated (median age 56.5 y [range 12-79], median 2 prior systemic tx). Only 9.0% of pts responded to last line of tx prior to study entry. ORR by IRC was 29.2% (95% CI, 22.7-36.5). Investigator assessed ORR was 26.4% (95% CI, 20.1-33.5). Responses were observed in 14 distinct tumor types, including gliomas, thoracic, gastrointestinal, gynecological, and rare tumors (Table). ORR in pts with FGFR mutations vs fusions was comparable (26.8% vs 27.0%, respectively). Median DOR, PFS, and OS were 7.1 mo (95% CI, 5.5-9.3), 5.2 mo (95% CI, 4.0-5.6), and 10.9 mo (95% CI, 7.9-14.3), respectively; DCR was 75.3% and CBR was 48.9%. All pts experienced TEAEs, including 69.1% with grade ≥ 3. Treatment-related serious TEAEs occurred in 7.3% of pts. Conclusions: RAGNAR data show, for the first time, evidence of efficacy for erda in heavily pretreated pts with a variety of hard to treat advanced FGFR+ malignancies, including glioblastoma, pancreatic, and salivary gland cancers. Safety was consistent with the known erda safety profile. Clinical trial information: NCT04083976. [Table: see text]

Efficacy and safety of erdafitinib in patients with locally advanced or metastatic urothelial carcinoma: long-term follow-up of a phase 2 study

BACKGROUND

Erdafitinib, a pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor, was shown to be clinically active and tolerable in patients with advanced urothelial carcinoma and prespecified FGFR alterations in the primary analysis of the BLC2001 study at median 11 months of follow-up. We aimed to assess the long-term efficacy and safety of the selected regimen of erdafitinib determined in the initial part of the study.

METHODS

The open-label, non-comparator, phase 2, BLC2001 study was done at 126 medical centres in 14 countries across Asia, Europe, and North America. Eligible patients were aged 18 years or older with locally advanced and unresectable or metastatic urothelial carcinoma, at least one prespecified FGFR alteration, an Eastern Cooperative Oncology Group performance status of 0-2, and progressive disease after receiving at least one systemic chemotherapy or within 12 months of neoadjuvant or adjuvant chemotherapy or were ineligible for cisplatin. The selected regimen determined in the initial part of the study was continuous once daily 8 mg/day oral erdafitinib in 28-day cycles, with provision for pharmacodynamically guided uptitration to 9 mg/day (8 mg/day UpT). The primary endpoint was investigator-assessed confirmed objective response rate according to Response Evaluation Criteria In Solid Tumors version 1.1. Efficacy and safety were analysed in all treated patients who received at least one dose of erdafitinib. This is the final analysis of this study. This study is registered with ClinicalTrials.gov, NCT02365597.

FINDINGS

Between May 25, 2015, and Aug 9, 2018, 2328 patients were screened, of whom 212 were enrolled and 101 were treated with the selected erdafitinib 8 mg/day UpT regimen. The data cutoff date for this analysis was Aug 9, 2019. Median efficacy follow-up was 24·0 months (IQR 22·7-26·6). The investigator-assessed objective response rate for patients treated with the selected erdafitinib regimen was 40 (40%; 95% CI 30-49) of 101 patients. The safety profile remained similar to that in the primary analysis, with no new safety signals reported with longer follow-up. Grade 3-4 treatment-emergent adverse events of any causality occurred in 72 (71%) of 101 patients. The most common grade 3-4 treatment-emergent adverse events of any cause were stomatitis (in 14 [14%] of 101 patients) and hyponatraemia (in 11 [11%]). There were no treatment-related deaths.

INTERPRETATION

With longer follow-up, treatment with the selected regimen of erdafitinib showed consistent activity and a manageable safety profile in patients with locally advanced or metastatic urothelial carcinoma and prespecified FGFR alterations.

FUNDING

Janssen Research & Development.

Preliminary results of molecular screening for FGFR alterations (alts) in the RAGNAR histology-agnostic study with the FGFR-inhibitor (FGFRi) erdafitinib

4081

Background: FGFR alts (mutations and fusions) have been reported in multiple advanced solid tumors at varying frequencies. These alts may function as oncogenic drivers of disease independent of the underlying tumor type. RAGNAR is an ongoing phase 2, histology-agnostic trial investigating the efficacy and safety of erdafitinib, a selective pan-FGFRi, in patients (pts) with advanced solid tumors and FGFR alts. Little is known about the incidence, diversity or predominant FGFR alts across solid tumors in the clinical setting. Here, we provide an update on molecular screening and enrollment in the primary analysis population. Methods: Pts with advanced solid tumors were molecularly screened for eligible FGFR alts via central next generation sequencing (NGS) or review of local NGS reports. Underlying tumor type, FGFR alts, demographics and key disease characteristics were collected at baseline. Results: From Nov 2019 to Jan 2021, 5758 pts were molecularly screened (central or local) in 15 countries. 191 pts (3.3%) fulfilled primary analysis molecular eligibility criteria; 110 pts were enrolled. Among pts enrolled, 14 (12.7%) had central screening and 96 (87.3%) had local NGS reports. Eligible FGFR alts were identified in 19 tumor types, including rare cancers and ones (eg, pancreatic) with a very low prevalence of FGFR alts in genomic databases (Table). Median age was 57 y, and 19 pts (17.3%) were < 40 y. Gender distribution was even. Conclusions: Findings from molecular screening in the RAGNAR study indicate a wide range of FGFR-altered tumor types, including a notable number of cancers where eligible FGFR alts were considered exceedingly rare (eg, pancreatic). These results demonstrate the feasibility of conducting clinical trials on pts with rare genetic alts by adopting a histology-agnostic design and using both central testing and local NGS reports for molecular screening. This approach also helps investigate rare tumors, where histology-specific trials are challenging. Efficacy and safety results from the RAGNAR study will help define the benefit of erdafitinib in FGFR-altered advanced solid tumors. Clinical trial information: NCT04083976. [Table: see text]

A phase II open-label study in adult and adolescent patients (pts) with advanced solid tumors harboring fibroblast growth factor receptor (FGFR) gene alterations

TPS480

Background: The pan- FGFR tyrosine kinase inhibitor erdafitinib is approved by the US Food and Drug Administration for adults with locally advanced or metastatic urothelial carcinoma and susceptible FGFR3/2 genetic alterations who have progressed during or after ≥ 1 line of prior platinum-containing chemotherapy. FGFR gene alterations are potential oncogenic drivers that have been reported in many solid tumors in adult and pediatric pts. Because of limited response to standard of care options in pts failing systemic therapy, there is strong rationale to assess the safety and efficacy of erdafitinib in adolescent and adult pts with advanced solid tumors and FGFR alterations. Methods: This phase 2, open-label study (RAGNAR/42756493CAN2002; NCT04083976) will include pts aged ≥ 12 years with histologically confirmed unresectable, locally advanced, or metastatic solid tumors (except urothelial tumors) harboring predefined FGFR mutations or fusions. Eligibility screening includes molecular screening for FGFR alterations by central or local next-generation sequencing assays, and other clinical criteria. Pts will enroll into either a broad panel cohort (BPC) of target FGFR alterations or an exploratory cohort (EC) for FGFR alterations that do not meet criteria for BPC. Approximately 280 pts (BPC, n = 240; EC, n = 40) will be enrolled. The primary efficacy end point is overall response rate (ORR) as assessed by the independent review committee. Secondary end points include investigator-assessed ORR, duration of response, disease control rate, progression-free survival, overall survival, safety, pharmacokinetics, and health-related quality of life. Safety assessments include adverse events, vital signs, electrocardiograms, physical examinations, laboratory tests, performance status assessment, growth assessments in adolescents, and ophthalmologic examination. As of December 2019, pts are being enrolled at ~158 sites in 15 countries. Results of this study will provide efficacy and safety data for erdafitinib across multiple solid tumors with FGFR alterations and evaluate the potential benefit of targeting the underlying altered biology of FGFR irrespective of tumor histology in adult and adolescent pts. Clinical trial information: NCT04083976.

ERDAFITINIB in locally advanced or metastatic urothelial carcinoma (mUC): Long-term outcomes in BLC2001

5015

Background: Erdafitinib (JNJ-42756493; ERDA) is the only pan-FGFR kinase inhibitor with US FDA approval for treatment of adults with mUC with susceptible FGFR3/2 alterations (alt) and who progressed on ≥ 1 line of prior platinum-based chemotherapy (chemo). Approval was based on data from the primary analysis of the pivotal BLC2001 trial1. Here we report long-term efficacy and safety data from the 8 mg/d continuous dose regimen in BLC2001. Methods: BLC2001 (NCT02365597) is a global, open-label, phase 2 trial of pts with measurable mUC with prespecified FGFR alt, ECOG 0-2, and progression during/following ≥ 1 line of prior chemo or ≤ 12 mos of (neo)adjuvant chemo, or were cisplatin ineligible, chemo naïve. The optimal schedule of ERDA determined in the initial part of the study was 8 mg/d continuous ERDA in 28-d cycles with uptitration to 9 mg/d (ERD 8 mg UpT) if a protocol-defined target serum phosphate level was not reached and if no significant treatment-related adverse events (TRAEs) occurred. Primary end point was the confirmed objective response rate (ORR=% complete response + % partial response). Key secondary end points were progression-free survival (PFS), duration of response (DOR) and overall survival (OS). Results: Median follow-up for 101 patients treated with ERDA 8 mg UpT was ~24 months. Confirmed ORR was 40%. Median DOR was 5.98 mos; 31% of responders had DOR ≥ 1 yr. Median PFS was 5.52 mos, median OS was 11.3 mos. 12-mos and 24-mos survival rates were 49% and 31%, respectively. Median treatment duration was 5.4 mos. The ERDA safety profile was consistent with the primary analysis. No new TRAEs were seen with longer follow-up. Central serous retinopathy (CSR) events occurred in 27% (27/101) of patients; 85% (23/27) were Grade 1 or 2; dosage was reduced in 13 pts, interrupted for 8, and discontinued for 3. On the data cut-off date, 63% (17/27) had resolved; 60% (6/10) of ongoing CSR events were Grade 1. There were no treatment-related deaths. Conclusions: With a median follow-up of 2 yrs, ERDA in mUC + FGFR alt showed a manageable safety profile and consistent efficacy, with median OS of 11.3 mos. 31% had a DOR ≥12 mos and 31% were alive at 24 mos. ERDA monotherapy vs. immune checkpoint inhibitor (PD-1) or chemo is being further analyzed in a randomized control study (THOR; NCT03390504).Reference: Loriot Y, et al. N Engl J Med. 2019;381:338-48. Clinical trial information: NCT02365597 .

A randomized phase II study of erdafitinib (ERDA) versus intravesical chemotherapy (IC) in patients with high-risk nonmuscle invasive bladder cancer (HR-NMIBC) with FGFR mutations or fusions, who recurred after Bacillus Calmette-Guérin (BCG) therapy

TPS603

Background: ERDA, an oral pan-FGFR inhibitor, is approved by the US FDA for metastatic urothelial carcinoma (mUC) with susceptible FGFR3 or FGFR2 gene alterations and progressed on/ or after at least 1 line of prior platinum-containing chemotherapy (PCC) including within 12 months of neoadjuvant/adjuvant PCC.1 Around 40% of patients with bladder cancer present with HR-NMIBC. First-line BCG therapy fails in 30-40% of patients and subsequent treatment options are limited. This study is designed to evaluate recurrence-free survival (RFS) following treatment with ERDA vs IC in patients with FGFR positive HR-NMIBC who recurred after BCG therapy. Methods: This is an open-label, multicenter, randomized, phase 2, safety and efficacy study of ERDA in adults with histologically confirmed HR-NMIBC and FGFR mutations or fusions. Inclusion criteria: ECOG status ≤1, adequate bone marrow, liver, renal function, and ineligibility for or declining cystectomy, with no history of prior FGFR inhibitors. Patients will be enrolled into 1 of 3 cohorts. Cohort 1 (n=240): high-grade disease Ta/T1 lesion (papillary only) with disease recurrence after BCG therapy will be randomized to ERDA or IC (investigator choice: gemcitabine or mitomycin C); Cohort 2 (n=20): carcinoma in situ (CIS) with/without papillary disease to receive ERDA monotherapy; Cohort 3 (n=20): marker lesion study in patients with intermediate-risk papillary disease only to receive ERDA monotherapy. Dose will be maintained at 8 mg, up-titrated to 9 mg, or withheld based on phosphate levels. Primary endpoint: Cohort 1- RFS; Secondary endpoints: Cohort 1 - time to progression and disease worsening, disease-specific survival (invasive bladder cancer), overall survival, RFS rate at 6, 12, 24 months, and RFS on subsequent anticancer therapy (RFS2). An IDMC will be commissioned for Cohort 1. Exploratory endpoints: Cohort 2- complete response (CR) rate at 6 months; Cohort 3- CR in marker lesion. Patients will be enrolled at sites in ~14 countries. EudraCT: 2019-002449-39. Loriot Y et al. N Engl J Med. 2019;381:338-48. Clinical trial information: 2019-002449-39.

Predictive value of fibroblast growth factor receptor (FGFR) alterations on anti-PD-(L)1 treatment outcomes in patients (Pts) with advanced urothelial cancer (UC): Pooled analysis of real-world data

493

Background: The tumor microenvironment in UC harboring FGFR gene alterations is characterized by decreased T-cell infiltration and low immune marker expression, potentially implicating suboptimal response to immune checkpoint inhibitors. The association between FGFR gene mutations/fusions and anti-PD-(L)1 treatment outcomes in advanced UC was assessed using real-world pt data. Methods: A pooled dataset of matched clinical and genomic data for advanced UC pts treated with anti-PD-(L)1 in any line from the Bladder Cancer Research Initiative for Drug Targets in Germany (BRIDGE) Consortium and UNC-CH was assessed. FGFR status was defined by a prespecified panel of FGFR2/3 mutations and fusions. Overall survival (OS) was analyzed using Kaplan-Meier estimates and Cox proportional hazards models. Multivariate analyses were performed using potential prognostic covariates (sex, age, baseline tumor stage, urothelial histology, smoking history, primary tumor location, and ECOG) in a Cox regression model for OS to assess their impact on the effect of FGFR alterations. Results: Median OS for FGFR+ pts (n=28) who received any line of anti-PD-(L)1 therapy was 9.5 mo vs 7.5 mo for FGFR− pts (n=139) (HR: 1.03, 95% CI: 0.60-1.76, p=0.93). Median OS for pts treated with first-line anti-PD-(L)1 was 5.42 mo in FGFR+ pts (n=10) and was not reached for FGFR− pts (n=31) (HR: 2.06, 95% CI: 0.68-6.24, p=0.19); median OS in second-line anti-PD-(L)1 was 6.5 mo (FGFR+; n=14) vs 5.7 mo (FGFR−; n=86) (HR: 0.89, 95% CI: 0.44-1.81, p=0.74). The multivariate analyses showed a significant trend of poorer OS in FGFR+ pts with first-line anti-PD-(L)1 (HR: 10.42, 95% CI: 1.45-74.97, p=0.02); wide CI may be attributed to small sample size for some categories in several covariates. Conclusions: Treatment with first-line anti-PD-(L)1 in FGFR+ pts may be associated with poorer OS outcomes in FGFR+ pts; however, this trend was not observed in FGFR+ pts treated with any line and second-line anti-PD-(L)1. Investigation of the predictive value of FGFR alterations to immunotherapy outcomes in larger real-world pt datasets is warranted.

FGFR-altered, advanced urothelial carcinoma (UC) and response to chemotherapy prior to receiving erdafitinib

4542

Background: FGFR-altered, advanced UC has predominantly a luminal 1 subtype, which is associated with lower response rates to immunotherapy and possibly also to chemotherapy. Objective response rates (ORR) for first-line cisplatin-based regimens, such as gemcitabine-cisplatin (gem/cis) and methotrexate-vinblastine-doxorubicin-cisplatin (MVAC), historically range between 45-60% and for gemcitabine-carboplatin (gem/carbo) 35-45%. However, the ORR on chemotherapy for the ~20% of patients with FGFR-altered tumors is unknown. Methods: BLC2001 (NCT02365597) is an ongoing global open-label phase 2 study of the pan-FGFR inhibitor erdafitinib in patients with locally advanced or metastatic UC with specific FGFR2/3 gene alterations. Patients who had received first-line (1L) or second-line (2L) chemotherapy for advanced UC were identified. Investigator-reported ORR (complete + partial responses) and median time to progression (TTP) on these pretreatments were analyzed. Results: Of 210 patients treated with erdafitinib in BLC2001, 191 had received prior systemic therapy including 184 and 83 patients who had received 1L and 2L chemotherapy, respectively. ORR were 29.3% (54/184; 95% CI 22.8%, 35.9%) to 1L chemotherapy and 24.1% (20/83; 95% CI 14.9%, 33.3%) to 2L chemotherapy. 1L therapy consisted of gem/cis in 94 patients, gem/carbo in 59 patients, and MVAC in 22 patients, with ORR (95% CI) of 35.1% (25.5%, 44.8%), 25.4% (14.3%, 36.5%), and 22.7% (5.2%, 40.2%), respectively. In the 2L setting, of 46 patients who had received a regimen containing a taxane (paclitaxel or docetaxel) or vinflunine, 8 patients (17.4%; 95% CI 6.4%, 28.3%) achieved an objective response. Median TTP was 7.16 mo (95% CI 6.18, 7.49) after 1L chemotherapy (7.6 mo for gem/cis, 6.3 mo for gem/carbo, and 5.3 mo for MVAC) and 4.35 mo (95% CI 3.3, 5.5) after 2L chemotherapy (3.6 mo for taxane or vinflunine). Conclusions: In this post-hoc analysis, the overall ORR to prior 1L chemotherapy was lower, but within the range expected based on historical data. Further investigation into the response to chemotherapy in FGFR alteration positive patients is warranted and may be useful for the development of 1L trials of combination therapy. Clinical trial information: NCT02365597.

Analysis of FGFR alterations from circulating tumor DNA (ctDNA) and Tissue in a phase II trial of erdafitinib in urothelial carcinoma (UC)

420

Background: Plasma samples from a Phase 2 study of the pan-FGFR inhibitor erdafitinib in advanced UC patients (pts) with FGFR mutations (mut) or fusions, were tested using next generation sequencing (NGS) for circulating tumor DNA (ctDNA), and results compared to central FGFR status determination from tissue. Methods: FGFR alterations were measured in archival tissue using an RNA-based RT-PCR test and compared with FGFR alterations identified in pre-treatment plasma specimens using the Guardant360 ctDNA test. Sensitivity of the ctDNA test to detect the FGFR alterations identified by RT-PCR from tissue, the proportion of pts with a study-eligible FGFR alteration in ctDNA, and the ability to detect a tissue FGFR alteration in ctDNA in relation to clinical response were assessed. Results: Samples from 155 pts with detectable baseline ctDNA were included. Overall, concordance between ctDNA and tissue-based FGFR results was 56% (87/155): 63% (77/122) for tissue mut-positive pts vs 24% (7/29) in fusion-positive pts. 61% of pts (94/155) were positive for a study-eligible FGFR alteration from blood-based testing in the tissue-positive population. The response rate was 47% (36/77) for patients for which FGFR mutations could be detected in blood (ctDNA- FGFR-positive) compared with 32% (14/44) in patients for which mutations were not detected in blood (ctDNA- FGFR-negative), with an estimated odds ratio of 1.882 (95% CI: 0.866; 4.090) Conclusions: The 63% concordance rate for detecting FGFR mut in temporally unmatched blood and tissue supports potential for patient selection with blood-based testing, while ctDNA FGFR fusion detection may require further optimization. Although differences in clinical response rate were observed between ctDNA- FGFR-positive and negative patients, the results were not statistically significant. Importantly, a proportion of ctDNA-negative pts responded to erdafitinib, indicating that tissue-based testing may be warranted for pts negative for FGFR alterations via blood-based testing. (BLC2001, NCT02365597). Clinical trial information: NCT02365597.

Predictive value of fibroblast growth factor receptor (FGFR) mutations and gene fusions on anti-PD-(L)1 treatment outcomes in patients (pts) with advanced urothelial cancer (UC)

419

Background: FGFR alterations have been shown to be associated with immunologically “cold” UC tumors with low immune marker expression and T cell infiltrate, a poorly receptive environment for immune checkpoint inhibitors. Using a real world matched clinical and genomic dataset of pts with advanced UC, we explored their predictive value in pts receiving anti-PD-(L)1 therapy. Methods: The Flatiron Health-Foundation Medicine Clinico-Genomic Database (CGDB) contained full clinical and treatment information and molecular data on a cohort of pts with confirmed advanced UC. The populations of interest are FGFR+ and FGFR- patients determined by the presence or absence of a prespecified panel of FGFR2/3 mutations and fusions. Overall survival (OS), measured from the start of anti-PD-(L)1 therapy, was analyzed using Kaplan-Meier estimation and Cox proportional hazards models adjusted for left truncation (delayed entry model). Results: 118 pts ( FGFR+ n = 26, FGFR- n = 92) treated with anti-PD-(L)1 therapy for advanced UC were assessed for OS. Median OS for FGFR+ pts who received any line of anti-PD-(L)1 therapy (n = 26) was 3.1 mo vs 6.1 mo for FGFR- pts (n = 92) (hazard ratio [HR] 1.33, 95% CI 0.78-2.26, p = 0.30). For first-line anti-PD-(L)1 therapy, median OS in FGFR+ pts (n = 12) was 4.7 mo vs 11.3 mo for FGFR- pts (n = 28) (HR 1.94, 95% CI: 0.78-4.82, p = 0.15); median OS in second-line were 3.1 mo (n = 12) vs 6.1 mo (n = 47), respectively (HR 1.17, 95% CI 0.53-2.59, p = 0.70). Per multivariate analysis, FGFR+ status appears to be associated with poorer OS in pts treated with any line of anti-PD-(L)1 therapy (HR 1.25, 95% CI 0.71-2.21, p = 0.43). Conclusions: These real-world data suggest that FGFR+ pts following anti-PD-(L)1 therapy for advanced UC may be associated with a trend in poorer overall survival outcome compared with FGFR- pts. These findings are in alignment with treatment history data from BLC2001 (Siefker-Radtke A, et al. ASCO-GU 2018), which showed low response rates to prior anti-PD-(L)1 therapies among FGFR+ pts.

Efficacy of programmed death 1 (PD-1) and programmed death 1 ligand (PD-L1) inhibitors in patients with FGFR mutations and gene fusions: Results from a data analysis of an ongoing phase 2 study of erdafitinib (JNJ-42756493) in patients (pts) with advanced urothelial cancer (UC)

450

Background: FGFR3 mutations appear to be enriched in luminal 1 UC, which have low expression of markers associated with an immune response, including CD8-T-effector gene expression levels. Objective response rate (ORR) to PD-1 and PD-L1 inhibitors in luminal 1 tumors appear lower (10-19%) than in infiltrated luminal 2 and basal 3 tumors (ORR 31-34%). This suggests FGFR3 mutations occur within a group of tumors less likely to benefit from immune checkpoint inhibition (ICI). Here we describe outcomes of a subgroup of pts with FGFR2/3 mutations and gene fusions, previously treated with PD-1/PD-L1 inhibitors and included in an ongoing erdafitinib phase 2 study. Methods: Patients who had received prior immunotherapy for advanced UC were selected from those enrolled on BLC2001, an ongoing phase 2, open-label study of the pan-FGFR inhibitor erdafitinib in subjects with advanced UC with specific FGFR2/3 gene alterations (NCT02365597). We explored investigator-reported clinical outcomes including ORR and median time to progression (TTP) of pts treated with ICI preceding erdafitinib therapy. Results: 28/203 pts had previously received anti PD-1 or anti PD-L1 treatment. In this subgroup, the median age was 67.0 y; 82% were male, 79% had an ECOG score ≤1, 36% had liver metastases, and 93% had ≥2 prior lines of systemic therapy. The response rate to anti PD-1/PD-L1 agents was 3.6% (95% CI, 0.1%-18.3%) with one partial response. Median TTP was 3.4 mo (range 2-15 mo; 95% CI, 2.3-4.9). Conclusions: In this post-hoc analysis, FGFR mutations and gene fusions seem to select for a group of pts less likely to respond to immune checkpoint inhibition. Although caution is needed due to the retrospective nature of the data, the presence of these alterations may reflect an unmet need with currently approved agents. This finding highlights the need for FGFR alteration testing and an effective FGFR-targeted therapy. Clinical trial information: NCT02365597.

Safety and activity of the pan-fibroblast growth factor receptor (FGFR) inhibitor erdafitinib in phase 1 study patients (Pts) with molecularly selected advanced cholangiocarcinoma (CCA)

4074

Background: Erdafitinib (JNJ-42756493) is a potent, oral pan-FGFR tyrosine kinase inhibitor that demonstrated encouraging preliminary clinical activity and manageable adverse events (AEs) in its first-in-human phase 1 study in advanced solid tumors (NCT01703481). Here we report results from pts with CCA from this study. Methods: This 4-part study enrolled pts age ≥ 18 years (y) with advanced solid tumors. Dose escalation (part 1) followed a 3+3 design, with pts receiving ascending doses of erdafitinib continuously or intermittently (7 days on/7 days off). Subsequent parts required FGFR gene alterations in the tumor, including activating mutations and translocations or other FGFR-activating aberrations. Part 2 was a pharmacodynamics cohort. Parts 3 and 4 were dose-expansion cohorts for recommended phase 2 doses of 9 mg once daily (QD) and 10 mg intermittently, respectively. Results: Eleven pts with FGFR-aberrant CCA were treated at 9 mg QD (n = 1) or 10 mg intermittent (n = 10). Median age was 60 y; 7 of 11 pts were female (64%). 73% of pts had ECOG performance status 1. All had prior systemic therapy. Median treatment duration with erdafitinib was 5.3 months (mo). Systemic erdafitinib exposure, per Cmax and AUC, in CCA pts was similar to other indications. The most common AEs were stomatitis (82%), hyperphosphatemia (64%), dry mouth (55%), dysgeusia (45%), dry skin (45%), and asthenia (45%), mostly grade 1/2 severity. No drug-related grade ≥3 AEs were reported in > 1 pt except grade 3 stomatitis (n = 2; 18%). The objective response rate, all confirmed partial responses (PRs) per RECIST 1.1, was 27.3% (3/11; 95% CI 6, 61); an additional 27.3% (3/11) had stable disease as their best response. Overall disease control rate was 55%. All 3 PRs were at the 10 mg intermittent dosage, and the median duration of response was 12.9 mo. With a median follow-up of 5.1 mo, median progression-free survival was 5.1 mo (95% CI 1.6, 16.4). As of the cutoff date, 2 pts continue on study treatment. Conclusions: Erdafitinib showed encouraging clinical activity and minimal toxicity in pts with advanced CCA and FGFR alterations. These results warrant further study. Clinical trial information: NCT01703481.

Acquired resistance to BRAF inhibitors mediated by a RAF kinase switch in melanoma can be overcome by cotargeting MEK and IGF-1R/PI3K

BRAF is an attractive target for melanoma drug development. However, resistance to BRAF inhibitors is a significant clinical challenge. We describe a model of resistance to BRAF inhibitors developed by chronic treatment of BRAF(V)⁶⁰⁰(E) melanoma cells with the BRAF inhibitor SB-590885; these cells are cross-resistant to other BRAF-selective inhibitors. Resistance involves flexible switching among the three RAF isoforms, underscoring the ability of melanoma cells to adapt to pharmacological challenges. IGF-1R/PI3K signaling was enhanced in resistant melanomas, and combined treatment with IGF-1R/PI3K and MEK inhibitors induced death of BRAF inhibitor-resistant cells. Increased IGF-1R and pAKT levels in a post-relapse human tumor sample are consistent with a role for IGF-1R/PI3K-dependent survival in the development of resistance to BRAF inhibitors.

Protein kinase C delta stimulates apoptosis by initiating G1 phase cell cycle progression and S phase arrest

Overexpression of protein kinase C delta (PKCdelta) stimulates apoptosis in a wide variety of cell types through a mechanism that is incompletely understood. PKCdelta-deficient cells are impaired in their response to DNA damage-induced apoptosis, suggesting that PKCdelta is required to mount an appropriate apoptotic response under conditions of stress. The mechanism through which it does so remains elusive. In addition to effects on cell survival, PKCdelta elicits pleiotropic effects on cellular proliferation. We now provide the first evidence that the ability of PKCdelta to stimulate apoptosis is intimately linked to its ability to stimulate G(1) phase cell cycle progression. Using an adenoviral-based expression system to express PKCalpha,-delta, and -epsilon in epithelial cells, we demonstrate that a modest increase in PKCdelta activity selectively stimulates quiescent cells to initiate G(1) phase cell cycle progression. Rather than completing the cell cycle, PKCdelta-infected cells arrest in S phase, an event that triggers caspase-dependent apoptotic cell death. Apoptosis was preceded by the activation of cell cycle checkpoints, culminating in the phosphorylation of Chk-1 and p53. Strikingly, blockade of S phase entry using the phosphatidylinositol 3-kinase inhibitor LY294002 prevented checkpoint activation and apoptosis. In contrast, inhibitors of mitogen-activated protein kinase cascades failed to prevent apoptosis. These findings demonstrate that the biological effects of PKCdelta can be extended to include positive regulation of G(1) phase cell cycle progression. Importantly, they reveal the existence of a novel, cell cycle-dependent mechanism through which PKCdelta stimulates cell death.