Translational insights and overall survival in the U31402-A-U102 study of patritumab deruxtecan (HER3-DXd) in EGFR-mutated NSCLC

BACKGROUND

Human epidermal growth factor receptor 3 (HER3) is broadly expressed in non-small-cell lung cancer (NSCLC) and is the target of patritumab deruxtecan (HER3-DXd), an antibody-drug conjugate consisting of a HER3 antibody attached to a topoisomerase I inhibitor payload via a tetrapeptide-based cleavable linker. U31402-A-U102 is an ongoing phase I study of HER3-DXd in patients with advanced NSCLC. Patients with epidermal growth factor receptor (EGFR)-mutated NSCLC that progressed after EGFR tyrosine kinase inhibitor (TKI) and platinum-based chemotherapy (PBC) who received HER3-DXd 5.6 mg/kg intravenously once every 3 weeks had a confirmed objective response rate (cORR) of 39%. We present median overall survival (OS) with extended follow-up in a larger population of patients with EGFR-mutated NSCLC and an exploratory analysis in those with acquired genomic alterations potentially associated with resistance to HER3-DXd.

PATIENTS AND METHODS

Safety was assessed in patients with EGFR-mutated NSCLC previously treated with EGFR TKI who received HER3-DXd 5.6 mg/kg; efficacy was assessed in those who also had prior PBC.

RESULTS

In the safety population (N = 102), median treatment duration was 5.5 (range 0.7-27.5) months. Grade ≥3 adverse events occurred in 76.5% of patients; the overall safety profile was consistent with previous reports. In 78/102 patients who had prior third-generation EGFR TKI and PBC, cORR by blinded independent central review (as per RECIST v1.1) was 41.0% [95% confidence interval (CI) 30.0% to 52.7%], median progression-free survival was 6.4 (95% CI 4.4-10.8) months, and median OS was 16.2 (95% CI 11.2-21.9) months. Patients had diverse mechanisms of EGFR TKI resistance at baseline. At tumor progression, acquired mutations in ERBB3 and TOP1 that might confer resistance to HER3-DXd were identified.

CONCLUSIONS

In patients with EGFR-mutated NSCLC after EGFR TKI and PBC, HER3-DXd treatment was associated with a clinically meaningful OS. The tumor biomarker characterization comprised the first description of potential mechanisms of resistance to HER3-DXd therapy.

Phase I study of the halichondrin B analogue eribulin mesylate in combination with cisplatin in advanced solid tumors

BACKGROUND

Eribulin mesylate is a synthetic macrocyclic ketone analogue of Halichondrin B that has demonstrated high antitumor activity in preclinical and clinical settings. This phase I study aimed to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetics in combination with cisplatin (CP) in patients with advanced solid tumours.

METHODS

Thirty-six patients with advanced solid tumours received eribulin mesylate 0.7-1.4 mg m(-2) and CP 60-75 mg m(-2). Eribulin mesylate was administered on days 1, 8, and 15 in combination with CP day 1 every 28-day cycle. The protocol was amended after dose level 4 (eribulin mesylate 1.4 mg m(-2), CP 60 mg m(-2)) when it was not feasible to administer eribulin mesylate on day 15 because of neutropenia; the treatment schedule was changed to eribulin mesylate on days 1 and 8 and CP on day 1 every 21 days.

RESULTS

On the 28-day schedule, three patients had DLT during the first cycle: grade (G) 4 febrile neutropenia (1.0 mg m(-2), 60 mg m(-2)); G 3 anorexia/fatigue/hypokalemia (1.2 mg m(-2), 60 mg m(-2)); and G 3 stomatitis/nausea/vomiting/fatigue (1.4 mg m(-2), 60 mg m(-2)). On the 21-day schedule, three patients had DLT during the first cycle: G 3 hypokalemia/hyponatremia (1.4 mg m(-2), 60 mg m(-2)); G 4 mucositis (1.4 mg m(-2), 60 mg m(-2)); and G 3 hypokalemia (1.2 mg m(-2), 75 mg m(-2)). The MTD and recommended phase II dose was determined as eribulin mesylate 1.2 mg m(-2) (days 1, 8) and CP 75 mg m(-2) (day 1), on a 21-day cycle. Two patients had unconfirmed partial responses (PR) (pancreatic and breast cancers) and two had PR (oesophageal and bladder cancers).

CONCLUSIONS

On the 21-day cycle, eribulin mesylate 1.2 mg m(-2), administered on days 1 and 8, in combination with CP 75 mg m(-2), administered on day 1 is well tolerated and showed preliminary anticancer activity.

Randomized phase II trial of pemetrexed/cisplatin with or without CBP501 in patients with advanced malignant pleural mesothelioma

BACKGROUND

CBP501, a synthetic duodecapeptide, increases cisplatin influx into tumor cells through an interaction with calmodulin enhancing cisplatin cytotoxicity, and effects cell cycle progression by abrogating DNA repair at the G2 checkpoint. In phase I clinical trials of CBP501 alone or in combination with cisplatin, the most common toxicity was infusion-related urticaria. Activity of CBP501 plus cisplatin was observed in patients with ovarian cancer and mesothelioma, including some patients previously treated with cisplatin.

METHODS

Chemotherapy naïve patients with unresectable MPM were stratified by histology and performance status, and randomized 2:1 to pemetrexed/cisplatin plus CBP501 25mg/m(2) IV (Arm A) or pemetrexed/cisplatin alone (Arm B). The primary endpoint was progression free survival (PFS) at 4 months.

RESULTS

65 patients were randomized, and 63 were treated. Patient characteristics in the two arms were balanced. Based on independent radiology review of the treated population, 25/40 patients (63%) in Arm A and 9/23 (39%) in Arm B had PFS≥4mo; the median PFS was 5.1mo (95% CI, 3.9, 6.5) vs 3.4mo (2.5, 6.7). Median OS was 13.3mo (9.2, 16.3) in Arm A and 12.8 (6.5, 16.1) in Arm B. Adverse events were not different than expected from standard chemotherapy, and comparable in the two arms, aside from infusion reactions which occurred in 70% of patients treated with CBP501.

CONCLUSIONS

While this randomized phase II trial met its primary endpoint of PFS at 4 months, other parameters such as response rate and overall survival suggest that the addition of CBP501 does not improve the efficacy of standard chemotherapy for MPM.

Long-term survival after high-dose chemotherapy followed by peripheral stem cell rescue for high-risk, locally advanced/inflammatory, and metastatic breast cancer

Patients with high-risk locally advanced/inflammatory and oligometastatic (≤3 sites) breast cancer frequently relapse or experience early progression. High-dose chemotherapy combined with peripheral stem cell rescue may prolong progression-free survival/relapse-free survival (PFS/RFS) and overall survival (OS). In this study, patients initiated high-dose chemotherapy with STAMP-V (carboplatin, thiotepa, and cyclophosphamide), ACT (doxorubicin, paclitaxel, and cyclophosphamide), or tandem melphalan and STAMP-V. Eighty-six patients were diagnosed with locally advanced/inflammatory (17 inflammatory) breast cancer, and 12 were diagnosed with oligometastatic breast cancer. Median follow-up was 84 months (range, 6-136 months) for patients with locally advanced cancer and 40 months (range, 24-62 months) for those with metastatic cancer. In the patients with locally advanced cancer, 5-year RFS and OS were 53% (95% CI, 41%-63%) and 71% (95% CI, 60%-80%), respectively, hormone receptors were positive in 74%, and HER2 overexpression was seen in 23%. In multivariate analysis, hormone receptor-positive disease and lower stage were associated with better 5-year RFS (60% for ER [estrogen receptor]/PR [progesterone receptor]-positive versus 30% for ER/PR-negative; P < .01) and OS (83% for ER/PR-positive versus 38% for ER/PR-negative; P < .001). In the patients with metastatic cancer, 3-year PFS and OS were 49% (95% CI, 19%-73%) and 73% (95% CI, 38%-91%), respectively. The favorable long-term RFS/PFS and OS for high-dose chemotherapy with peripheral stem cell rescue in this selected patient population reflect the relative safety of the procedure and warrant validation in defined subgroups through prospective, randomized, multi-institutional trials.

A phase I/II prospective, single arm trial of gefitinib, trastuzumab, and docetaxel in patients with stage IV HER-2 positive metastatic breast cancer

Inhibition of the HER-2 pathway via the monoclonal antibody trastuzumab has had a major impact in treatment of HER-2 positive breast cancer, but de novo or acquired resistance may reduce its effectiveness. The known interplay between the epidermal growth factor receptor (EGFR) and HER-2 receptors and pathways creates a rationale for combined anti-EGFR and anti-HER-2 therapy in HER-2 positive metastatic breast cancer (MBC), and toxicities associated with the use of multiple chemotherapeutic agents together with biological therapies may also be reduced. We conducted a prospective, single arm, phase I/II trial to determine the efficacy and toxicity of the combination of trastuzumab with the EGFR inhibitor gefitinib and docetaxel, in patients with HER-2 positive MBC. The maximum tolerated dose (MTD) was determined in the phase I portion. The primary end point of the phase II portion was progression-free survival (PFS). Immunohistochemical analysis of biomarker expression of the PKA-related proteins cAMP response element-binding protein (CREB), phospho-CREB and DARPP-32 (dopamine and cAMP-regulated phosphoprotein of 32 kDa) plus t-DARPP (the truncated isoform of DARPP-32); PTEN; p-p70 S6K; and EGFR was conducted on tissue from metastatic sites. Nine patients were treated in the phase I portion of the study and 22 in the phase II portion. The MTD was gefitinib 250 mg on days 2-14, trastuzumab 6 mg/kg, and docetaxel 60 mg/m(2) every 21 days. For the 29 patients treated at the MTD, median PFS was 12.7 months, with complete and partial response rates of 18 and 46%, and a stable disease rate of 29%. No statistically significant correlation was found between response and expression of any biomarkers. We conclude that the combination of gefitinib, trastuzumab, and docetaxel is feasible and effective. Expression of the biomarkers examined did not predict outcome in this sample of HER-2 overexpressing metastatic breast cancer.

Randomized, double-blind, placebo-controlled phase II study of carboplatin and paclitaxel with or without vorinostat, a histone deacetylase inhibitor (HDAC), for first-line therapy of advanced non-small cell lung cancer (NCI 7863)

8004

Background: Vorinostat, a HDAC inhibitor, enhances paclitaxel and platinum-mediated anti-cancer activity in preclinical studies by enhanced tubulin acetylation and DNA fragmentation respectively. Promising activity with carboplatin (C), paclitaxel (P), and vorinostat in patients with advanced NSCLC in the phase I study (Ramalingam et al, Clin Cancer Res, 2007) prompted this placebo-controlled, randomized phase II study. Methods: Pts. with stage IIIB (wet) or IV NSCLC, performance status (PS) 0/1, no prior therapy and adequate bone marrow, renal and hepatic function were randomized (2:1) for therapy with PC with either vorinostat or placebo. Treatment consisted of C: AUC=6 mg/ml.min; and P 200 mg/m2 both given on day 3 along with either vorinostat (400 mg PO QD) or placebo on days 1–14 of each 3 wk cycle to a maximum of 6 cycles. The estimated sample size to demonstrate a 50% improvement in response rate for vorinostat over placebo was 93 pts. (one-sided P, type I error 10%). Results: Ninety-four pts. were enrolled (vorinostat-64; placebo-32). Pts. baseline characteristics were similar between the two arms (median age 64, male 60%, PS 0 40%, brain mets 16%). Median # cycles: vorinostat-3.5; placebo - 4. The confirmed response rate was superior with vorinostat over placebo (34% vs. 12.5%, P = 0.02). At the time of analysis, the preliminary median PFS for vorinostat and placebo were 5.75 and 4.1 m respectively (ITT). Follow up for survival is ongoing. Common grade 3/4 toxicities (vorinostat vs. placebo): neutropenia (44% vs. 47%); thrombocytopenia (33% vs. 16%); fatigue (13% vs. 3%); hyponatremia (21% vs. 6%); diarrhea (5% vs. 0). Discontinuation from study after cycle 1 was higher with vorinostat (27% vs. 16%). Biomarker studies on baseline tumor tissue and peripheral blood cells are ongoing. Conclusions: Administration of vorinostat with carboplatin and paclitaxel resulted in a significantly superior response rate for pts.with advanced NSCLC. HDAC inhibition is a novel therapeutic strategy for treatment of NSCLC. Supported by ASCO Career Development Award to S.S.Ramalingam, and NCI NO1-CM-62209, NO1-CM-62201, NO1-CM-62208.

[Table: see text]

Efficacy and safety of PF-00299804 (PF299) in patients (pt) with advanced NSCLC after failure of at least one prior chemotherapy regimen and prior treatment with erlotinib (E): A two-arm, phase II trial

8063

Background: Options are limited for pts with NSCLC following chemotherapy and E. PF299 is an oral irreversible small molecule inhibitor of the HER-1,-2, and -4 tyrosine kinases. Based on non-clinical and phase I NSCLC data, this ongoing phase II U.S. trial evaluates PF299 in pts with NSCLC (KRAS wild-type) who have progressive disease after at least 1 prior chemotherapy regimen and after E. Methods: Pts were enrolled by histology: adenocarcinoma (Arm A) and non-adenocarcinoma (Arm B), and received PF299 45 mg QD. Endpoints include objective response rate, duration of response, progression-free survival, survival, safety/tolerability, and pharmacokinetics. Pharmacodynamic endpoints include assessment of serum levels of HER2 and EGFR extracellular domains. Tissue and blood KRAS assays, and EGFR studies on available tissue, are also being performed. Forty-four and 22 response-evaluable pts were planned to be enrolled into Arms A and B respectively. Results: Thirty-four pts with progressive NSCLC (25 female, 14 smoker) have enrolled to date (Arm A: 30; Arm B: 4): median duration of prior E: 11.5 months; median time since E: 2.5 months. Among 20 response-evaluable pts, stable disease (SD) was observed in 9/18 pts in Arm A, and 1/2 pts in Arm B: median duration of SD: 11.5 weeks [range 6+, 32+ weeks]. Observation of disease control included pts who had recently (≤8 weeks) discontinued E; and also pts whose tumor had known EGFR T790M mutations. At time of data cutoff, confirmation per RECIST of 2 partial responses is pending. The most common treatment-related AEs were skin and gastrointestinal disorders, with grade 3 AEs in 19% and 13% of pts, respectively. Two pts experienced grade 4 pulmonary embolus/dyspnea deemed possibly treatment-related, both in the setting of progressive disease. Conclusions: PF299 shows encouraging activity in NSCLC pts after failure of prior chemotherapy and E. The AE profile was predictable and consistent with the prior phase I trial. At submission, enrollment in the adenocarcinoma arm is complete and enrollment in the non-adenocarcinoma arm continues; updated efficacy data and tumor characterization will be presented.

[Table: see text]

The combination of the HER2 antibody trastuzumab, the EGFR tyrosine kinase inhibitor gefitinib, and docetaxel as first-line therapy in patients with HER2 overexpressing stage IV breast carcinoma

1057

Background: Interference with both HER2 and epidermal growth factor (EGFR) dependent pathways may improve therapeutic efficacy of docetaxel (doc) in pts with HER2 overexpressing (+) BC. Methods: Patients (pts) without prior chemotherapy (Rx) exposure for stage IV HER-2 + BC were enrolled. Prior hormonal or adjuvant Rx inclusive of taxane or trastuzumab (tras) were allowed. A left ventricular ejection fraction of > 45% and ECOG performance status of ≥ 2 were required. Pts were to receive doc 75 m2, tras every 3 weeks, and gefitinib (gef) 250 mg daily. BC samples from 12 pts were analyzed by FISH for HER2 and EGFR amplification (amp), and topoisomerase II (topo II) amp or loss. IHC was to be performed to examine p-Src, p-STAT3, Ki67 and survivin expression. Results: The median age was 49 (range, 34–67) and ECOG performance status 0.5 (0–1). The first 9 patients received gef 250 mg daily; 2 pts received dox 75 mg/m2 and developed grade 3 febrile neutropenia (neu), hence, additional pts received doc at 60 mg/m2: 3 more episodes of grade 3 neu were seen. Gef was held due to grade 3 dermatitis (2 pts) and diarrhea (2 pts). Pts received a median of 6 cycles (3–10). Gef schedule then was changed, and was prescribed on days 2–14, only. Three of the next 9 pts experienced grades 3 or 4 neu, and we observed 3 cases of grade 3 gastrointestinal toxicities; pts were able to receive 11 + (range; 5–25+) cycles on this schedule (p<0.04). There were 4 complete (CR)and 6 partial R (23 % CR, 59 % overall R), and 3 pts had stable disease (SD; all R and SD confirmed); 3 pts progressed at 4, 4, and 5 mos, 1 pt was inevaluable. The median time to progression is 12 + mos. Samples from 3 pts revealed topo II amplification and one pt sample showed loss of one topo II allele; none were amplified for EGFR. Outcome will be correlated with IHC defined signal trasduction status and proliferation rates. Conclusions: The combination of doc, tras, and short course of gef is feasible, with encouraging R and SD rates and time to progression. Further exploration of simultaneous blockage of multiple signal transduction pathways is indicated in combination with chemoRx. Supported by NCI CA33572 and by a grant from AstraZeneca.

No significant financial relationships to disclose.

Phase II study of hydroxyurea and gemcitabine in recurrent or persistent squamous cell cancer of the head and neck

15524

Background: Preclinical studies demonstrate increased activity when hydroxyurea (HU) is given prior to gemcitabine (G). Clinical feasibility was demonstrated in a phase I trial (Yen, et. al. Cancer Chemother Pharmacol. 2002 ). We performed a phase II trial treating patients (pts) with squamous cell head and neck cancers (SCCHN). Methods: Pts had metastatic or incurable locally recurrent SCCHN. Prior chemotherapy was allowed, but not required. Serum creatinine ≤2.0 mg/dl, bilirubin <3.0 gm/dl, AST/ALT <5× ULN and KPS ≥60% were required. HU 500 mg orally every 6 hours for 4 doses was given on day 1 of a 21-day cycle. On day 2, 6 hours after HU, G 750 mg/m2 was given over 30 minutes. This sequence was repeated on day 8 and 9. After 8 pts, G was given at 500 mg/m2. G-CSF was given on day 10 and until the WBC count was >10k/μl. The primary endpoint was response rate (RR), with an early stopping rule for <3 objective responders among the first 18 pts. Results: 22 pts (17 M) were accrued, 16 with prior chemotherapy and 19 with prior radiation. The first 8 pts received G 750 mg/m2. Two pts died of neutropenic fever (NF) during course 1. Subsequently 14 pts received G 500 mg/m2. 18 pts were evaluable for response, with 1 still in follow-up. Partial response was seen in 1 pt, stable disease in 9, and progressive disease in 8. The overall median survival of the 22 pts was 6 months and the median progression free survival (PFS) was 2 months. The primary toxicity was hematologic. Grade 4 neutropenia was seen in 7/22 pts during the 1st cycle (5 at G 750 mg/m2) with 5 cases of NF. Grade 4 thrombocytopenia occurred in 1 pt at G 750 mg/m2. Conclusions: The RR and PFS of treated pts treated were not promising and further accrual is not planned. Analysis of biopsy materials is planned to see if responsive pts can be selected. (Supported by NCI Grant CA33572).

No significant financial relationships to disclose.