Homologous recombination deficiency should be tested for in patients with advanced stage high-grade serous ovarian cancer aged 70 years and over.

OBJECTIVE: Due to limited data on homologous recombination deficiency (HRD) in older patients (≥ 70 years) with advanced stage high grade serous ovarian cancer (HGSC), we aimed to determine the rates of HRD at diagnosis in this age group. METHODS: From the Phase 3 trial VELIA the frequency of HRD and BRCA1/2 pathogenic variants (PVs) was compared between younger (< 70 years) and older participants. HRD and somatic(s) BRCA1/2 pathogenic variants (PVs) were determined at diagnosis using Myriad myChoice® CDx and germline(g) BRCA1/2 PVs using Myriad BRACAnalysis CDx®. HRD was defined if a BRCA PV was present, or the genomic instability score (GIS) met threshold (GIS ≥ 33 & ≥ 42 analyzed). RESULTS: Of 1140 participants, 21% were ≥ 70 years. In total, 26% (n = 298) had a BRCA1/2 PV and HRD, 29% (n = 329) were HRD/BRCA wild-type, 33% (n = 372) non-HRD, and 12% HR-status unknown (n = 141). HRD rates were higher in younger participants, 59% (n = 476/802), compared to 40% (n = 78/197) of older participants (GIS ≥ 42) [p < 0.001]; similar rates demonstrated with GIS ≥ 33, 66% vs 48% [p < 0.001]. gBRCA PVs observed in 24% younger vs 8% of older participants (p < 0.001); sBRCA in 8% vs 10% (p = 0.2559), and HRD (GIS ≥ 42) not due to gBRCA was 35% vs 31% (p = 0.36). CONCLUSIONS: HRD frequency was similar in participants aged < 70 and ≥ 70 years (35% vs 31%) when the contribution of gBRCA was excluded; rates of sBRCA PVs were also similar (8% v 10%), thus underscoring the importance of HRD and BRCA testing at diagnosis in older patients with advanced HGSC given the therapeutic implications.

Depatuxizumab mafodotin in EGFR-amplified newly diagnosed glioblastoma: A phase III randomized clinical trial.

BACKGROUND: Approximately 50% of newly diagnosed glioblastomas (GBMs) harbor epidermal growth factor receptor gene amplification (EGFR-amp). Preclinical and early-phase clinical data suggested efficacy of depatuxizumab mafodotin (depatux-m), an antibody-drug conjugate comprised of a monoclonal antibody that binds activated EGFR (overexpressed wild-type and EGFRvIII-mutant) linked to a microtubule-inhibitor toxin in EGFR-amp GBMs. METHODS: In this phase III trial, adults with centrally confirmed, EGFR-amp newly diagnosed GBM were randomized 1:1 to radiotherapy, temozolomide, and depatux-m/placebo. Corneal epitheliopathy was treated with a combination of protocol-specified prophylactic and supportive measures. There was 85% power to detect a hazard ratio (HR) ≤0.75 for overall survival (OS) at a 2.5% 1-sided significance level (ie traditional two-sided p ≤ 0.05) by log-rank testing. RESULTS: There were 639 randomized patients (median age 60, range 22-84; 62% men). Prespecified interim analysis found no improvement in OS for depatux-m over placebo (median 18.9 vs. 18.7 months, HR 1.02, 95% CI 0.82-1.26, 1-sided p = 0.63). Progression-free survival was longer for depatux-m than placebo (median 8.0 vs. 6.3 months; HR 0.84, 95% confidence interval [CI] 0.70-1.01, p = 0.029), particularly among those with EGFRvIII-mutant (median 8.3 vs. 5.9 months, HR 0.72, 95% CI 0.56-0.93, 1-sided p = 0.002) or MGMT unmethylated (HR 0.77, 95% CI 0.61-0.97; 1-sided p = 0.012) tumors but without an OS improvement. Corneal epitheliopathy occurred in 94% of depatux-m-treated patients (61% grade 3-4), causing 12% to discontinue. CONCLUSIONS: Interim analysis demonstrated no OS benefit for depatux-m in treating EGFR-amp newly diagnosed GBM. No new important safety risks were identified.

CA-125 KELIM as a Potential Complementary Tool for Predicting Veliparib Benefit: An Exploratory Analysis From the VELIA/GOG-3005 Study.

PURPOSE: In VELIA trial, veliparib combined with carboplatin-paclitaxel, followed by maintenance (veliparib-throughout) was associated with improved progression-free survival (PFS) compared with carboplatin-paclitaxel alone in patients with high-grade ovarian carcinomas. We explored the prognostic value of the modeled cancer antigen (CA)-125 elimination rate constant K (KELIM), which is known to be an indicator of the intrinsic tumor chemosensitivity (the faster the rate of CA-125 decline, the higher the KELIM and the higher the chemosensitivity), and its association with benefit from veliparib. PATIENTS AND METHODS: Individual KELIM values were estimated from longitudinal CA-125 kinetics. Patients were categorized as having favorable (≥ median) or unfavorable (< median) KELIM. The prognostic value of KELIM for veliparib-related PFS benefit was explored in cohorts treated with primary or interval debulking surgery, according to the surgery completeness, the disease progression risk group, and the homologous recombination (HR) status (BRCA mutation, HR deficiency [HRD], or HR proficiency [HRP]). RESULTS: The data from 854 of 1,140 enrolled patients were analyzed (primary debulking surgery, n = 700; interval debulking surgery, n = 154). Increasing KELIM values were associated with higher benefit from veliparib in HRD cancer, as were decreasing KELIM values in HRP cancer. The highest PFS benefit from veliparib was observed in patients with both favorable KELIM and BRCA mutation (hazard ratio, 0.28; 95% CI, 0.13 to 0.61) or BRCA wild-type HRD cancer (hazard ratio, 0.43; 95% CI, 0.26 to 0.70), consistent with the association between poly (adenosine diphosphate-ribose) polymerase inhibitor efficacy and platinum sensitivity. In contrast, seventy-four percent of patients with a BRCA mutation and unfavorable KELIM progressed within 18 months while on veliparib. The patients with HRP cancer and unfavorable KELIM might have benefited from the veliparib chemosensitizing effect. CONCLUSION: In addition to HRD/BRCA status, the tumor primary chemosensitivity observed during the first-line chemotherapy might be another complementary determinant of poly (adenosine diphosphate-ribose) polymerase inhibitor efficacy.

Impact of homologous recombination status and responses with veliparib combined with first-line chemotherapy in ovarian cancer in the Phase 3 VELIA/GOG-3005 study.

OBJECTIVE: In the Phase 3 VELIA trial (NCT02470585), PARP inhibitor (PARPi) veliparib was combined with first-line chemotherapy and continued as maintenance for patients with ovarian carcinoma enrolled regardless of chemotherapy response or biomarker status. Here, we report exploratory analyses of the impact of homologous recombination deficient (HRD) or proficient (HRP) status on progression-free survival (PFS) and objective response rates during chemotherapy. METHODS: Women with Stage III-IV ovarian carcinoma were randomized to veliparib-throughout, veliparib-combination-only, or placebo. Stratification factors included timing of surgery and germline BRCA mutation status. HRD status was dichotomized at genomic instability score 33. During combination therapy, CA-125 levels were measured at baseline and each cycle; radiographic responses were assessed every 9 weeks. RESULTS: Of 1140 patients randomized, 742 had BRCA wild type (BRCAwt) tumors (HRP, n = 373; HRD/BRCAwt, n = 329). PFS hazard ratios between veliparib-throughout versus control were similar in both BRCAwt populations (HRD/BRCAwt: 22.9 vs 19.8 months; hazard ratio 0.76; 95% confidence interval [CI] 0.53-1.09; HRP: 15.0 vs 11.5 months; hazard ratio 0.765; 95% CI 0.56-1.04). By Cycle 3, the proportion with ≥90% CA-125 reduction from baseline was higher in those receiving veliparib (pooled arms) versus control (34% vs 23%; P = 0.0004); particularly in BRCAwt and HRP subgroups. Complete response rates among patients with measurable disease after surgery were 24% with veliparib (pooled arms) and 18% with control. CONCLUSIONS: These results potentially broaden opportunities for PARPi utilization among patients who would not qualify for frontline PARPi maintenance based on other trials.

Matched cohort study of germline BRCA mutation carriers with triple negative breast cancer in brightness.

In the BrighTNess trial, carboplatin added to neoadjuvant chemotherapy (NAC) was associated with increased pathologic complete response (pCR) rates in patients with stage II/III triple-negative breast cancer (TNBC). In this matched cohort study, cases with a germline BRCA1/2 mutation (gBRCA; n = 75) were matched 1:2 with non-gBRCA controls (n = 150) by treatment arm, lymph node status, and age to evaluate pCR rates and association of benefit from platinum/PARP inhibitors with validated RNA expression-based immune, proliferation, and genomic instability scores among gBRCA with the addition of carboplatin ± veliparib to NAC. Among the well-matched cohorts, odds of pCR were not higher in gBRCA cancers who received standard NAC with carboplatin (OR 0.24, 95% CI [0.04-1.24], p = 0.09) or with carboplatin/veliparib (OR 0.44, 95% CI [0.10-1.84], p = 0.26) compared to non-gBRCA cancers. Higher PAM50 proliferation, GeparSixto immune, and CIN70 genomic instability scores were each associated with higher pCR rate in the overall cohort, but not specifically in gBRCA cases. In this study, gBRCA carriers did not have higher odds of pCR than non-gBRCA controls when carboplatin ± veliparib was added to NAC, and showed no significant differences in molecular, immune, chromosomal instability, or proliferation gene expression metrics.

ABBV-176, a PRLR antibody drug conjugate with a potent DNA-damaging PBD cytotoxin and enhanced activity with PARP inhibition.

BACKGROUND: Prolactin receptor (PRLR) is an attractive antibody therapeutic target with expression across a broad population of breast cancers. Antibody efficacy, however, may be limited to subtypes with either PRLR overexpression and/or those where estradiol no longer functions as a mitogen and are, therefore, reliant on PRLR signaling for growth. In contrast a potent PRLR antibody-drug conjugate (ADC) may provide improved therapeutic outcomes extending beyond either PRLR overexpressing or estradiol-insensitive breast cancer populations. METHODS: We derived a novel ADC targeting PRLR, ABBV-176, that delivers a pyrrolobenzodiazepine (PBD) dimer cytotoxin, an emerging class of warheads with enhanced potency and broader anticancer activity than the clinically validated auristatin or maytansine derivatives. This agent was tested in vitro and in vivo cell lines and patient derived xenograft models. RESULTS: In both in vitro and in vivo assays, ABBV-176 exhibits potent cytotoxicity against multiple cell line and patient-derived xenograft breast tumor models, including triple negative and low PRLR expressing models insensitive to monomethyl auristatin (MMAE) based PRLR ADCs. ABBV-176, which cross links DNA and causes DNA breaks by virtue of its PBD warhead, also demonstrates enhanced anti-tumor activity in several breast cancer models when combined with a poly-ADP ribose polymerase (PARP) inhibitor, a potentiator of DNA damage. CONCLUSIONS: Collectively the efficacy and safety profile of ABBV-176 suggest it may be an effective therapy across a broad range of breast cancers and other cancer types where PRLR is expressed with the potential to combine with other therapeutics including PARP inhibitors.

Association of Immunophenotype With Pathologic Complete Response to Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer: A Secondary Analysis of the BrighTNess Phase 3 Randomized Clinical Trial.

IMPORTANCE: Adding carboplatin to standard neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC) likely benefits a subset of patients; however, determinants of benefit are poorly understood. OBJECTIVE: To define the association of molecular subtype, tumor proliferation, and immunophenotype with benefit of carboplatin added to NAC for patients with stages II to III TNBC. DESIGN, SETTING, AND PARTICIPANTS: This was a prespecified secondary analysis of a phase 3, double-blind, randomized clinical trial (BrighTNess) that enrolled 634 women across 145 centers in 15 countries. Women with clinical stages II to III TNBC who had undergone pretreatment biopsy were eligible to participate. Whole transcriptome RNA sequencing was performed on the biopsy specimens. The prespecified end point was association of pathologic complete response (pCR) with gene expression-based molecular subtype, with secondary end points investigating established signatures (proliferation, immune) and exploratory analyses of immunophenotype. Data were collected from April 2014 to March 2016. The study analyses were performed from January 2018 to March 2019. INTERVENTIONS: Neoadjuvant chemotherapy with paclitaxel followed by doxorubicin and cyclophosphamide, or this same regimen with carboplatin or carboplatin plus veliparib. MAIN OUTCOMES AND MEASURES: Association of gene expression-based molecular subtype (PAM50 and TNBC subtypes) with pCR. RESULTS: Of the 634 women (median age, 51 [range, 22-78] years) enrolled in BrighTNess, 482 (76%) patients had evaluable RNA sequencing data, with similar baseline characteristics relative to the overall intention-to-treat population. Pathologic complete response was significantly more frequent in PAM50 basal-like vs nonbasal-like cancers overall (202 of 386 [52.3%] vs 34 of 96 [35.4%]; P = .003). Carboplatin benefit was not significantly different in basal-like vs nonbasal-like subgroups (P = .80 for interaction). In multivariable analysis, proliferation (hazard ratio, 0.36; 95% CI, 0.21-0.61; P < .001) and immune (hazard ratio, 0.62; 95% CI, 0.49-0.79; P < .001) signatures were independently associated with pCR. Tumors above the median for proliferation and immune signatures had the highest pCR rate (84 of 125; 67%), while those below the median for both signatures had the lowest pCR rate (42 of 125; 34%). Exploratory gene expression immune analyses suggested that tumors with higher inferred CD8+ T-cell infiltration may receive greater benefit with addition of carboplatin. CONCLUSIONS AND RELEVANCE: In this secondary analysis of a randomized clinical trial, triple-negative breast cancer subtyping revealed high pCR rates in basal-like and immunomodulatory subsets. Analysis of biological processes related to basal-like and immunomodulatory phenotypes identified tumor cell proliferation and immune scores as independent factors associated with achieving pCR; the benefit of carboplatin on pCR was seen across all molecular subtypes. Further validation of immunophenotype with existing biomarkers may help to escalate or de-escalate therapy for patients with TNBC. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02032277.

A phase 1 study evaluating safety and pharmacokinetics of losatuxizumab vedotin (ABBV-221), an anti-EGFR antibody-drug conjugate carrying monomethyl auristatin E, in patients with solid tumors likely to overexpress EGFR.

Losatuxizumab vedotin (formerly ABBV-221) is a second-generation antibody-drug conjugate targeting epidermal growth factor receptor (EGFR). In this multicenter phase 1 study, eligible patients with EGFR-dependent solid tumors received losatuxizumab vedotin (3 + 3 design) intravenously at starting dose of 0.3 mg/kg over 3 h per 21-day cycle, with alternate dosing schedules utilized (2 weeks on/1 week off or weekly) to mitigate infusion reactions. Forty-five patients received ≥1 doses of losatuxizumab vedotin (13 colon, 6 non-small cell lung cancer, 5 head and neck [HNC], 5 glioblastoma multiforme, 2 breast, 14 other). Tumor samples were evaluated for EGFR protein expression by immunohistochemistry, EGFR and EGFR ligand mRNA expression by RNAseq, and results compared with outcome. Most common adverse events were infusion-related reaction (22/45; 49%) and fatigue (20/45; 44%). While most infusion reactions were grade ≤ 2, four patients experienced grade ≥3 infusion reactions. Several infusion reaction mitigation strategies were explored. Because of the high incidence of infusion reactions, the trial was stopped and the maximum tolerated dose was not reached. The last cleared dose: 6 mg/kg/cycle. Nineteen patients (42%) had stable disease; 4 remained on study >6 months. One HNC patient with increased levels of EGFR and EGFR ligands (amphiregulin, epiregulin) achieved a confirmed partial response. Pharmacokinetic analysis of losatuxizumab vedotin showed exposures appeared to be approximately dose-proportional. The high frequency of infusion reactions necessitated early closure of this trial. The detailed mitigation strategies used in this protocol for infusion-related reactions may provide beneficial information for trial design of agents with high infusion reaction rates.

Veliparib with First-Line Chemotherapy and as Maintenance Therapy in Ovarian Cancer.

BACKGROUND: Data are limited regarding the use of poly(adenosine diphosphate [ADP]-ribose) polymerase inhibitors, such as veliparib, in combination with chemotherapy followed by maintenance as initial treatment in patients with high-grade serous ovarian carcinoma. METHODS: In an international, phase 3, placebo-controlled trial, we assessed the efficacy of veliparib added to first-line induction chemotherapy with carboplatin and paclitaxel and continued as maintenance monotherapy in patients with previously untreated stage III or IV high-grade serous ovarian carcinoma. Patients were randomly assigned in a 1:1:1 ratio to receive chemotherapy plus placebo followed by placebo maintenance (control), chemotherapy plus veliparib followed by placebo maintenance (veliparib combination only), or chemotherapy plus veliparib followed by veliparib maintenance (veliparib throughout). Cytoreductive surgery could be performed before initiation or after 3 cycles of trial treatment. Combination chemotherapy was 6 cycles, and maintenance therapy was 30 additional cycles. The primary end point was investigator-assessed progression-free survival in the veliparib-throughout group as compared with the control group, analyzed sequentially in the BRCA-mutation cohort, the cohort with homologous-recombination deficiency (HRD) (which included the BRCA-mutation cohort), and the intention-to-treat population. RESULTS: A total of 1140 patients underwent randomization. In the BRCA-mutation cohort, the median progression-free survival was 34.7 months in the veliparib-throughout group and 22.0 months in the control group (hazard ratio for progression or death, 0.44; 95% confidence interval [CI], 0.28 to 0.68; P<0.001); in the HRD cohort, it was 31.9 months and 20.5 months, respectively (hazard ratio, 0.57; 95 CI, 0.43 to 0.76; P<0.001); and in the intention-to-treat population, it was 23.5 months and 17.3 months (hazard ratio, 0.68; 95% CI, 0.56 to 0.83; P<0.001). Veliparib led to a higher incidence of anemia and thrombocytopenia when combined with chemotherapy as well as of nausea and fatigue overall. CONCLUSIONS: Across all trial populations, a regimen of carboplatin, paclitaxel, and veliparib induction therapy followed by veliparib maintenance therapy led to significantly longer progression-free survival than carboplatin plus paclitaxel induction therapy alone. The independent value of adding veliparib during induction therapy without veliparib maintenance was less clear. (Funded by AbbVie; VELIA/GOG-3005 ClinicalTrials.gov number, NCT02470585.).

Epidermal growth factor receptor (EGFR) amplification rates observed in screening patients for randomized trials in glioblastoma.

PURPOSE: Epidermal growth factor receptor (EGFR) amplification has been reported to occur in ~ 50% of glioblastomas (GBMs). We are conducting several global studies that require central testing for EGFR amplification during screening, representing an opportunity to confirm the frequency of amplification in GBM in a large cohort and to evaluate whether EGFR amplification differs by region of the world. METHODS: EGFR amplification was measured by fluorescence in situ hybridization during screening for therapeutic trials of an EGFR antibody-drug conjugate: two Phase 2/3 global trials (INTELLANCE-1, INTELLANCE-2), and a Japanese Phase 1/2 trial (INTELLANCE-J). We evaluated the proportion of tumor tissue samples harboring EGFR amplification among those tested and differences in amplification frequency by geography. RESULTS: EGFR was amplified in 54% of 3150 informative cases screened for INTELLANCE-1 and -2, consistent with historic controls, but was significantly lower in patients from Asia versus the rest of the world (35% vs. 56%, P < 0.0030). The independent INTELLANCE-J trial validated this finding (33% amplified of 153 informative cases). CONCLUSIONS: EGFR amplification occurs less frequently in patients from Asia than elsewhere. Further study is required to understand biological differences to optimize treatment in glioblastoma.

Comparison of Biomarker Assays for EGFR: Implications for Precision Medicine in Patients with Glioblastoma.

PURPOSE: Patients with glioblastoma (GBM) have a poor prognosis and are in desperate need of better therapies. As therapeutic decisions are increasingly guided by biomarkers, and EGFR abnormalities are common in GBM, thus representing a potential therapeutic target, we systematically evaluated methods of assessing EGFR amplification by multiple assays. Specifically, we evaluated correlation among fluorescence in situ hybridization (FISH), a standard assay for detecting EGFR amplification, with other methods.Experimental Design: Formalin-fixed, paraffin-embedded tumor samples were used for all assays. EGFR amplification was detected using FISH (N = 206) and whole-exome sequencing (WES, N = 74). EGFR mRNA expression was measured using reverse transcription-polymerase chain reaction (RT-PCR, N = 206) and transcriptome profiling (RNAseq, N = 64). EGFR protein expression was determined by immunohistochemistry (IHC, N = 34). Significant correlations among various methods were determined using Cohen's kappa (κ = 0.61-0.80 defines substantial agreement) or R 2 statistics. RESULTS: EGFR mRNA expression levels by RNA sequencing (RNAseq) and RT-PCR were highly correlated with EGFR amplification assessed by FISH (κ = 0.702). High concordance was also observed when comparing FISH to WES (κ = 0.739). RNA expression was superior to protein expression in delineating EGFR amplification. CONCLUSIONS: Methods for assessing EGFR mRNA expression (RT-PCR, RNAseq) and copy number (WES), but not protein expression (IHC), can be used as surrogates for EGFR amplification (FISH) in GBM. Collectively, our results provide enhanced understanding of available screening options for patients, which may help guide EGFR-targeted therapeutic approaches.

Safety and efficacy of depatuxizumab mafodotin + temozolomide in patients with EGFR-amplified, recurrent glioblastoma: results from an international phase I multicenter trial.

Background: Patients with glioblastoma (GBM) have a dismal prognosis. Nearly all will relapse with no clear standard of care for recurrent disease (rGBM). Approximately 50% of patients have tumors harboring epidermal growth factor receptor (EGFR) amplification. The antibody-drug conjugate depatuxizumab mafodotin (depatux-m) binds cells with EGFR amplification, is internalized, and releases a microtubule toxin, killing the cell. Here we report efficacy, safety and pharmacokinetics (PK) of depatux-m + temozolomide (TMZ) in patients with EGFR-amplified rGBM. Methods: M12-356 (NCT01800695) was an open-label study encompassing patients with newly diagnosed or rGBM across 3 treatment arms. Results are reported for adults with EGFR-amplified, measurable rGBM who received depatux-m (0.5-1.5 mg/kg) on days 1 and 15, and TMZ (150-200 mg/m2) on days 1-5 in a 28-day cycle. Patients were bevacizumab and nitrosourea naïve. Results: There were 60 patients, median age 56 years (range, 20-79). Fifty-nine patients previously received TMZ. Common adverse events (AEs) were blurred vision (63%), fatigue (38%), and photophobia (35%). Grades 3/4 AEs were split between ocular and non-ocular AEs, occurring in 22% of patients each. Systemic PK exposure of depatux-m was dose proportional. The objective response rate was 14.3%, the 6-month progression-free survival rate was 25.2%, and the 6-month overall survival rate was 69.1%. Conclusions: Depatux-m + TMZ displayed an AE profile similar to what was described previously. Antitumor activity in this TMZ-refractory population was encouraging. Continued study of depatux-m in patients with EGFR-amplified, newly diagnosed, or recurrent GBM is ongoing in 2 global, randomized trials (NCT02573324, NCT02343406).

Efficacy and safety results of depatuxizumab mafodotin (ABT-414) in patients with advanced solid tumors likely to overexpress epidermal growth factor receptor.

BACKGROUND: Epidermal growth factor receptor (EGFR) alterations are associated with multiple cancers. Current EGFR-directed therapies have led to increased efficacy but are associated with specific side effects. The antibody-drug conjugate depatuxizumab mafodotin (depatux-m) targets EGFR with a monoclonal antibody linked to a cytotoxin, and is highly tumor-specific. METHODS: This phase 1/2 study evaluated the safety, pharmacokinetics, and efficacy of depatux-m in patients who had advanced solid tumors with known wild-type EGFR overexpression, amplification, or mutated EGFR variant III. A 3 + 3 dose escalation was used, and 2 dosing schedules were evaluated. Depatux-m also was manufactured under an alternate process to reduce the drug load and improve the safety profile, and it was tested at the maximum tolerated dose (MTD). In another cohort, prolonged infusion time of depatux-m was evaluated; and a cohort with confirmed EGFR amplification also was evaluated at the MTD. RESULTS: Fifty-six patients were treated. The MTD and the recommended phase 2 dose for depatux-m was 3.0 mg/kg. Common adverse events (AEs) were blurred vision (48%) and fatigue (41%). A majority of patients (66%) experienced 1 or more ocular AEs. Grade 3 or 4 AEs were observed in 43% of patients. One patient with EGFR-amplified, triple-negative breast cancer had a partial response. Stable disease was observed in 23% of patients. Pharmacokinetics revealed that depatux-m exposures were approximately dose-proportional. CONCLUSIONS: Depatux-m resulted in infrequent nonocular AEs but increased ocular AEs. Patient follow-up confirmed that ocular AEs were reversible. Lowering the drug-antibody ratio did not decrease the number of ocular AEs. A partial response in 1 patient with EGFR-amplified disease provides the opportunity to study depatux-m in diseases with a high incidence of EGFR amplification. Cancer 2018;124:2174-83. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Safety, pharmacokinetics, and antitumor response of depatuxizumab mafodotin as monotherapy or in combination with temozolomide in patients with glioblastoma.

Background: We recently reported an acceptable safety and pharmacokinetic profile of depatuxizumab mafodotin (depatux-m), formerly called ABT-414, plus radiation and temozolomide in newly diagnosed glioblastoma (arm A). The purpose of this study was to evaluate the safety and pharmacokinetics of depatux-m, either in combination with temozolomide in newly diagnosed or recurrent glioblastoma (arm B) or as monotherapy in recurrent glioblastoma (arm C). Methods: In this multicenter phase I dose escalation study, patients received depatux-m (0.5-1.5 mg/kg in arm B, 1.25 mg/kg in arm C) every 2 weeks by intravenous infusion. Maximum tolerated dose (MTD), recommended phase II dose (RP2D), and preliminary efficacy were also determined. Results: Thirty-eight patients were enrolled as of March 1, 2016. The most frequent toxicities were ocular, occurring in 35/38 (92%) patients. Keratitis was the most common grade 3 adverse event observed in 6/38 (16%) patients; thrombocytopenia was the most common grade 4 event seen in 5/38 (13%) patients. The MTD was set at 1.5 mg/kg in arm B and was not reached in arm C. RP2D was declared as 1.25 mg/kg for both arms. Depatux-m demonstrated a linear pharmacokinetic profile. In recurrent glioblastoma patients, the progression-free survival (PFS) rate at 6 months was 30.8% and the median overall survival was 10.7 months. Best Response Assessment in Neuro-Oncology responses were 1 complete and 2 partial responses. Conclusion: Depatux-m alone or in combination with temozolomide demonstrated an acceptable safety and pharmacokinetic profile in glioblastoma. Further studies are currently under way to evaluate its efficacy in newly diagnosed (NCT02573324) and recurrent glioblastoma (NCT02343406).

Efficacy of depatuxizumab mafodotin (ABT-414) monotherapy in patients with EGFR-amplified, recurrent glioblastoma: results from a multi-center, international study.

PURPOSE: Patients with recurrent glioblastoma (rGBM) have a poor prognosis. Epidermal growth factor receptor (EGFR) gene amplification is present in ~ 50% of glioblastomas (GBMs). Depatuxizumab mafodotin (depatux-m), formerly ABT-414, is an antibody-drug conjugate that preferentially binds cells with EGFR amplification, is internalized and releases a potent antimicrotubule agent, monomethyl auristatin F (MMAF). Here we report the safety, pharmacokinetics, and efficacy of depatux-m monotherapy at the recommended Phase 2 dose (RPTD) in patients with EGFR-amplified, rGBM. METHODS: M12-356 (NCT01800695) is an open-label study with three escalation and expansion cohorts. Sixty-six patients with EGFR-amplified, rGBM were treated with depatux-m monotherapy at 1.25 mg/kg intravenously every 2 weeks. Adults with measurable rGBM, who were bevacizumab-naïve, with EGFR amplification were eligible. RESULTS: Among 66 patients, median age was 58 years (range 35-80). All patients were previously treated with radiotherapy/temozolomide. The most common adverse events (AEs) were eye related (91%), including blurred vision (65%), dry eye (29%), keratitis, and photophobia (27% each). Grade 3/4 AEs occurred in 42% of all patients, and ocular Grade 3/4 AEs occurred in 33% of patients overall. One patient (2%) had a Grade 4 ocular AE. Ocular AEs were manageable and usually resolved once treatment with depatux-m ceased. The objective response rate was 6.8%, the 6-month progression-free survival rate was 28.8%, and the 6-month overall survival rate was 72.5%. CONCLUSION: Depatux-m monotherapy displayed frequent but mostly Grade 1/2 ocular toxicities. A PFS6 of 28.8% was observed in this rGBM population, warranting further study.

Plasma biomarker signature associated with improved survival in advanced non-small cell lung cancer patients on linifanib.

OBJECTIVES: Linifanib, a potent and selective inhibitor of the tyrosine kinase activity of vascular endothelial growth factor and platelet-derived growth factor receptors, has clinical activity in advanced non-small cell lung cancer (NSCLC) both as monotherapy in the relapsed setting or with carboplatin and paclitaxel in the first-line setting. Though benefit was observed in unselected patient populations, identification of predictive biomarkers is critical for further development of this novel agent. MATERIALS AND METHODS: Data from 4 randomized studies in relapsed NSCLC with linifanib (n=116) or other treatments (n=125) were examined in an exploratory analysis to identify a biomarker profile predictive of favorable survival. RESULTS: A signature combining the established tumor markers carcinoembryonic antigen (CEA) and cytokeratin 19 fragments (CYFRA 21-1) was predictive of a favorable outcome. This signature was associated with improved survival in patients receiving linifanib monotherapy (hazard ratio [HR]=0.51 vs signature negative; p=0.002), but not in those receiving other anti-cancer treatments (p=0.716). This signature was validated on baseline plasma samples from patients enrolled in a randomized trial of daily linifanib 7.5 mg, linifanib 12.5 mg, or placebo added to first-line carboplatin and paclitaxel chemotherapy for advanced, nonsquamous NSCLC. Only linifanib-treated signature-positive patients had significant improvement in progression-free survival (PFS). Median PFS with placebo was 5.2 months versus 10.2 months (HR=0.49, p=0.049) for those receiving linifanib 7.5mg, and 8.3 months (HR=0.38, p=0.029) for linifanib 12.5 mg. Overall survival for signature-positive patients was 11.3 months with placebo, 12.5 months with linifanib 7.5mg (HR=1.02, p=0.758), and 17.4 months with linifanib 12.5 mg (HR=0.54, p=0.137). CONCLUSION: This baseline plasma biomarker signature is associated with improved outcome in advanced NSCLC patients receiving linifanib. Utility of the biomarker signature in patient selection for linifanib therapy in NSCLC merits evaluation in larger, prospective trials that are powered to detect a survival benefit.

An open-label, phase 1 study evaluating safety, tolerability, and pharmacokinetics of linifanib (ABT-869) in Japanese patients with solid tumors.

PURPOSE: This phase 1 study assessed the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of linifanib in Japanese patients with advanced solid tumors. METHODS: Patients were assigned to one of four sequential cohorts (0.05, 0.10, 0.20, or 0.25 mg/kg) of oral, once-daily linifanib on a 21-day cycle. Adverse events (AEs) were assessed per common terminology criteria for adverse events v3.0; tumor responses were assessed by response evaluation criteria in solid tumors. RESULTS: Eighteen patients were enrolled. Eleven (61%) received ≥3 prior therapies. Dose-limiting toxicities were Grade 3 ALT increase (0.10 mg/kg linifanib) and Grade 1 T-wave inversion (0.25 mg/kg linifanib) requiring dose interruption for >7 days and discontinuation on day 29. The most common linifanib-related AE was hypertension. Other significant treatment-related AEs included proteinuria, fatigue, and palmar-plantar erythrodysaesthesia. Linifanib pharmacokinetics were dose-proportional across 0.10-0.25 mg/kg. Two patients (11.1%) had confirmed partial responses, 12 had a best response of stable disease (11 had stable disease for ≥12 weeks), and four patients were not evaluable due to incomplete data. Four patients (lung cancer, breast cancer, thymic cancer, sarcoma) have continued linifanib for ≥48 weeks (range, 48-96+ weeks). CONCLUSION: Linifanib was well tolerated with promising preliminary clinical activity in Japanese patients. Later-phase global studies examining linifanib efficacy will include Japanese patients.

Recombinant kringle 5 from plasminogen antagonises hepatocyte growth factor-mediated signalling.

The blood protein plasminogen is proteolytically cleaved to produce angiostatin and kringle 5 (K5), both of which are known angiogenesis inhibitors. A common structural element between K5, angiostatin and other endogenous angiogenesis inhibitors is the presence of the kringle protein-interacting domain. Another kringle domain-containing protein, hepatocyte growth factor (HGF), promotes angiogenesis by binding to and stimulating the tyrosine kinase receptor Met. HGF binding to Met is dependent on the kringle domains of HGF. Because both K5 and HGF contain kringle motifs and because these proteins have opposite effects on angiogenesis, we hypothesised that K5 can antagonise HGF-mediated signalling in a Met-dependent manner. We determined that K5 binding to H1299 cells is competed by HGF suggesting that these two proteins bind to the same protein. Purified K5 immunoprecipitates with Met and this interaction is abolished by increasing doses of HGF. Using proliferation, phosphorylation of Met and Akt as markers of HGF activity, we determined that K5 inhibits HGF-mediated signalling. Taken together, these data support a model by which K5 binds to Met and functions as a competitive antagonist of HGF signalling and presents a novel mechanism of action of K5.

Activation of p53 by MEG3 non-coding RNA.

MEG3 is a maternally expressed imprinted gene suggested to function as a non-coding RNA. Our previous studies suggest that MEG3 has a function of tumor suppression. The tumor suppressor p53 plays a central role in tumor suppression and mediates the functions of many other tumor suppressors. Therefore, we hypothesized that MEG3 functions through activation of p53. We found that transfection of expression constructs for MEG3 and its isoforms results in a significant increase in p53 protein levels and dramatically stimulates p53-dependent transcription from a p53-responsive promoter. Using this as the functional assay, we demonstrated that the open reading frames encoded by MEG3 transcripts are not required for MEG3 function, and the folding of MEG3 RNA is critical to its function, supporting the concept that MEG3 functions as a non-coding RNA. We further found that MEG3 stimulates expression of the growth differentiation factor 15 (GDF15) by enhancing p53 binding to the GDF15 gene promoter. Interestingly, MEG3 does not stimulate p21(CIP1) expression, suggesting that MEG3 can regulate the specificity of p53 transcriptional activation. p53 degradation is mainly mediated by the mouse double minute 2 homolog (MDM2). We found that MDM2 levels were down-regulated in cells transfected with MEG3, suggesting that MDM2 suppression contributes at least in part to p53 accumulation induced by MEG3. Finally, we found that MEG3 is able to inhibit cell proliferation in the absence of p53. These data suggest that MEG3 non-coding RNA may function as a tumor suppressor, whose action is mediated by both p53-dependent and p53-independent pathways.

Regulation of growth hormone expression by Delta-like protein 1 (Dlk1).

Delta-like protein 1 (Dlk1) is a transmembrane protein characterized by epidermal growth factor (EGF)-like repeats. Dlk1, which is also known as preadipocyte factor 1 (pref-1) because of its ability to inhibit preadipocyte differentiation, regulates the differentiation of several other cell types through unknown mechanisms. To elucidate Dlk1 functions, identification of Dlk1-regulated target genes is critical. The observation that Dlk1 is expressed in many endocrine tissues suggests that Dlk1 may have endocrine-related functions. Because Dlk1 is expressed in GH producing cells, we hypothesize that one function of Dlk1 is to regulate GH expression. We found that GH mRNA, protein, and secretion were significantly decreased in GH3 pituitary cell clones that stably express Dlk1. In contrast, Dlk1 expression was unable to alter prolactin expression. Co-transfection of GH3 cells with a GH promoter-regulated reporter gene showed that Dlk1 repressed GH promoter activity. Deletion and mutation analysis of the GH promoter indicated that Pit-1 binding sites in the GH promoter are required for Dlk1-mediated repression. Furthermore, Dlk1 expression represses Pit-1-mediated transcription when both proteins are co-expressed in MCF-7 cells. Deletion analysis of Dlk1 revealed that the ability of Dlk1 to regulate GH promoter activity is independent of both its EGF-like repeats and its ability to modulate MAP kinase activity. The observation that Dlk1 regulates GH expression identifies the first endocrine function of Dlk1, establishes GH as a Dlk1-regulated target gene, and provides a model system to facilitate studies of Dlk1-mediated signaling.