Development and validation of a prognostic model for overall survival in chemotherapy-naïve men with metastatic castration-resistant prostate cancer

Background

Prognostic models are needed that reflect contemporary practice for men with metastatic castration-resistant prostate cancer (mCRPC). We sought to identify predictive and prognostic variables for overall survival (OS) in chemotherapy-naïve men with mCRPC treated with enzalutamide.

Patients and methods

Patients from the PREVAIL trial database (enzalutamide versus placebo) were randomly split 2 : 1 into training (n = 1159) and testing (n = 550) sets. Using the training set, 23 predefined variables were analyzed and a multivariable model predicting OS was developed and validated in an independent testing set.

Results

Patient characteristics and outcomes were well balanced between training and testing sets; median OS was 32.7 months in each. The final validated multivariable model included 11 independent prognostic variables. Median OS for low-, intermediate-, and high-risk groups (testing set) defined by prognostic risk tertiles were not yet reached (NYR) (95% CI NYR-NYR), 34.2 months (31.5-NYR), and 21.1 months (17.5-25.0), respectively. Hazard ratios (95% CI) for OS in the low- and intermediate-risk groups versus high-risk group were 0.20 (0.14-0.29) and 0.40 (0.30-0.53), respectively. Secondary outcomes of response and progression differed widely in model-defined risk groups. Enzalutamide improved outcomes in all prognostic risk groups.

Conclusions

Our validated prognostic model incorporates variables routinely collected in chemotherapy-naïve men with mCRPC treated with enzalutamide, identifying subsets of patients with widely differing survival outcomes that provide useful information for external validation, patient care, and clinical trial design.

Trial registration

ClinicalTrials.gov: NCT01212991.

A multicentre, phase IIa study of zolbetuximab as a single agent in patients with recurrent or refractory advanced adenocarcinoma of the stomach or lower oesophagus: the MONO study

BACKGROUND

Claudin 18.2 (CLDN18.2) is physiologically confined to gastric mucosa tight junctions; however, upon malignant transformation, perturbations in cell polarity lead to CLDN18.2 epitopes being exposed on the cancer cell surface. The first-in-class monoclonal antibody, zolbetuximab (formerly known as IMAB362), binds to CLDN18.2 and can induce immune-mediated lysis of CLDN18.2-positive cells.

PATIENTS AND METHODS

Patients with advanced gastric, gastro-oesophageal junction (GEJ) or oesophageal adenocarcinomas with moderate-to-strong CLDN18.2 expression in ≥50% of tumour cells received zolbetuximab intravenously every 2 weeks for five planned infusions. At least three patients were enrolled in two sequential cohorts (cohort 1300 mg/m2; cohort 2600 mg/m2); additional patients were enrolled into a dose-expansion cohort (cohort 3600 mg/m2). The primary end point was the objective response rate [ORR: complete and partial response (PR)]; secondary end points included clinical benefit [ORR+stable disease (SD)], progression-free survival, safety/tolerability, and zolbetuximab pharmacokinetic profile.

RESULTS

From September 2010 to September 2012, 54 patients were enrolled (cohort 1, n = 4; cohort 2, n = 6; cohort 3, n = 44). Three patients in cohort 1 and 25 patients in cohorts 2/3 received at least 5 infusions. Antitumour activity data were available for 43 patients, of whom 4 achieved PR (ORR 9%) and 6 (14%) had SD for a clinical benefit rate of 23%. In a subgroup of patients with moderate-to-high CLDN18.2 expression in ≥70% of tumour cells, ORR was 14% (n = 4/29). Treatment-related adverse events occurred in 81.5% (n = 44/54) patients; nausea (61%), vomiting (50%), and fatigue (22%) were the most frequent.

CONCLUSIONS

Zolbetuximab monotherapy was well tolerated and exhibited antitumour activity in patients with CLDN18.2-positive advanced gastric or GEJ adenocarcinomas, with response rates similar to those reported for single-agent targeted agents in gastric/GEJ cancer trials.

CLINICALTRIALS.GOV NUMBER

NCT01197885.

A phase III, randomized, open-label study of ASP8273 versus erlotinib or gefitinib in patients with advanced stage IIIB/IV non-small-cell lung cancer

BACKGROUND

ASP8273, a novel, small molecule, irreversible tyrosine kinase inhibitor (TKI) specifically inhibits the epidermal growth factor receptor (EGFR) in patients with activating mutations or EGFR T790M resistance mutations. The current study examines the efficacy, safety, and tolerability of ASP8273 versus erlotinib or gefitinib in patients with non-small-cell lung cancer (NSCLC) with activating EGFR mutations not previously treated with an EGFR inhibitor.

PATIENTS AND METHODS

This global, phase III, open-label, randomized study evaluated ASP8273 versus erlotinib/gefitinib in patients with locally advanced, metastatic, or unresectable stage IIIB/IV NSCLC with activating EGFR mutations. They were ineligible if they received prior chemotherapy for metastatic disease. The primary end point was progression-free survival (PFS), and secondary end points included overall survival, investigator-assessed PFS, best overall response rate (ORR), disease control rate, duration of response (DoR), and the safety/tolerability profile.

RESULTS

Patients (n = 530) were randomized 1 : 1 to receive ASP8273 (n = 267) or erlotinib/gefitinib (n = 263). Patient demographics between both treatment groups were generally balanced. Median PFS was 9.3 months (95% CI 5.6-11.1 months) for patients receiving ASP8273 and 9.6 months (95% CI 8.8-NE) for the erlotinib/gefitinib group, with a hazard ratio of 1.611 (P = 0.992). The ORR in the ASP8273 group was 33% (95% CI 27.4-39.0) versus 47.9% (95% CI 41.7-54.1) in the erlotinib/gefitinib group. Median DoR was similar for both groups (9.2 months for ASP8273 versus 9.0 months for erlotinib/gefitinib). More grade ≥3 treatment-emergent adverse events (TEAEs) occurred in patients receiving ASP8273 than in those receiving erlotinib/gefitinib (54.7% versus 43.5%). An independent data monitoring committee carried out an interim safety analysis and recommended discontinuing the study due to toxicity and limited predicted efficacy of ASP8273 relative to erlotinib/gefitinib.

CONCLUSIONS

First-line ASP8273 did not show improved PFS or equivalent toxicities versus erlotinib/gefitinib.

CLINICALTRIAL.GOV NUMBER

NCT02588261.

Radiographic progression with nonrising PSA in metastatic castration-resistant prostate cancer: post hoc analysis of PREVAIL

BACKGROUND

Advanced prostate cancer is a phenotypically diverse disease that evolves through multiple clinical courses. PSA level is the most widely used parameter for disease monitoring, but it has well-recognized limitations. Unlike in clinical trials, in practice, clinicians may rely on PSA monitoring alone to determine disease status on therapy. This approach has not been adequately tested.

METHODS

Chemotherapy-naive asymptomatic or mildly symptomatic men (n=872) with metastatic castration-resistant prostate cancer (mCRPC) who were treated with the androgen receptor inhibitor enzalutamide in the PREVAIL study were analyzed post hoc for rising versus nonrising PSA (empirically defined as >1.05 vs ⩽1.05 times the PSA level from 3 months earlier) at the time of radiographic progression. Clinical characteristics and disease outcomes were compared between the rising and nonrising PSA groups.

RESULTS

Of 265 PREVAIL patients with radiographic progression and evaluable PSA levels on the enzalutamide arm, nearly one-quarter had a nonrising PSA. Median progression-free survival in this cohort was 8.3 months versus 11.1 months in the rising PSA cohort (hazard ratio 1.68; 95% confidence interval 1.26-2.23); overall survival was similar between the two groups, although less than half of patients in either group were still at risk at 24 months. Baseline clinical characteristics of the two groups were similar.

CONCLUSIONS

Non-rising PSA at radiographic progression is a common phenomenon in mCRPC patients treated with enzalutamide. As restaging in advanced prostate cancer patients is often guided by increases in PSA levels, our results demonstrate that disease progression on enzalutamide can occur without rising PSA levels. Therefore, a disease monitoring strategy that includes imaging not entirely reliant on serial serum PSA measurement may more accurately identify disease progression.

ABT-263 activity and safety in patients with relapsed or refractory lymphoid malignancies in particular chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL)

8574

Background: ABT-263, a novel, orally bioavailable, BH3 mimetic, binds with high affinity (Ki ≤ 1nM) and inhibits multiple antiapoptotic Bcl-2 family proteins. ABT-263 displays activity (EC50 ≤ 1μM) against human lymphoid and small cell lung cancer cell lines. Mechanism based preclinical toxicities include reductions in circulating lymphocytes, apoptosis of circulating platelets, and decreased spermatogenesis, mediated by inhibition of Bcl-2, Bcl-XL, and Bcl-w, respectively. Methods: Safety and activity of ABT-263 in 2 enrolling phase I studies in relapsed/refractory lymphoid malignancies (M06–814) and CLL (M06–873) was evaluated. Patients (pts) were dosed on days 1–14 of a 21 d cycle, 10–440mg (M06–814) or 10–250mg (M06–873). Continuous 21/21 d dosing (CD) post lead-in dose is being explored in both studies. Results: 55 pts, 14/21 d dosing, enrolled in the 2 studies. ABT-263 PK were linear from 10 - 440mg (N=55) and the terminal half-life was 14 - 20 h (n=35). Among 27 CLL/SLL pts, 3 have confirmed radiographic partial responses (PR) (99%, 92% and 72%) and 2 have unconfirmed regressions, 51% and 72%. 6 pts maintained a ≥50% decrease in circulating lymphocytes for ≥ 2 months and 11 pts have stable disease; of these 5 experienced minor radiographic responses (range of 36% to 49%). In addition, among 40 (M06–814) lymphoma pts, 3 with follicular lymphoma achieved PR and one had a minor response (49% regression). With CD dosing (16 pts), activity includes 1 unconfirmed PR in SLL & and 3 CLL pts with ≥50% lymphocyte reduction for ≥2 months duration. Pharmacodynamic toxicities included dose-dependent thrombocytopenia (TCP) resulting from on-target activity against Bcl-XL. Dose limiting toxicities, 14/21 d dosing, in M06–814 occurred at 160mg (bronchitis), 315mg (elevated ALT and grade 4 TCP) and 440mg (worsening pleural effusion in a pt with underlying afib), and in M06–873 at 110mg (tumor lysis and grade 4 TCP) and 250mg (grade 4 TCP). Conclusions: ABT-263 showed favorable PK and safety profiles with anti-tumor activity in relapsed/refractory CLL/SLL and follicular lymphoma. Identification of optimal dose and schedule for phase II trials continues.

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