The OBR Blog

Today, four plenary sessions dropped at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting featured results from three phase 3 trials: ENZAMET, ANNOUNCE, and POLO as well as encouraging data about the impact of Medicaid expansion under the Affordable Care Act (ACA).

Medicaid Expansion Closes Racial Disparities Gap (Abstract LBA1)

When the ACA was implemented in 2010, states were permitted to expand Medicaid access. A retrospective study found that states that expanded Medicaid had a reduction in racial disparities in time to cancer treatment.

Using data from electronic health records, researchers observed timely treatment (ie, treatment initiation within 30 days of diagnosis) for adult patients younger than 65 with a diagnosis of advanced or metastatic cancer. The study population included more than 30,000 patients, and depending on the Medicaid expansion status of the state in which they lived, patients were labeled as participating in Medicaid expansion or not.

When Medicaid was not expanded, a significantly lower percentage of African American patients received timely treated compared with white patients (43.5% vs 48.3%; P<0.001). When Medicaid was expanded, this racial disparity gap did not exist (49.6% vs 50.3%; P=0.63).

“The disparities disappeared under the expansion,” summed up study presenter Amy Davidoff, PhD, Yale University.

Enzalutamide for the Win in Metastatic Prostate Cancer (Abstract LBA2)

Enzalutamide outperformed standard non-steroidal anti-androgens for men with metastatic hormone-sensitive prostate cancer, according to data from an interim analysis of the randomized, phase 3 ENZAMET trial.

Patients (n=1,125) received a testosterone-suppressing medicine followed by treatment with enzalutamide or a standard of care non-steroidal anti-androgen: bicalutamide, nilutamide, or flutamide.

For the overall patient population, the 3-year overall survival (OS) rate was 79% for men treated with enzalutamide; 72% for men treated with bicalutamide, nilutamide, or flutamide. This resulted in a 33% reduced likelihood in risk of death for men treated with enzalutamide (HR=0.67; 95% CI, 0.52-0.86; P=0.002).

In particular, an OS benefit for enzalutamide was seen among men with high volume disease (HR=0.74; 95% CI, 0.55-1.01) or no planned early docetaxel (HR=0.51; 95% CI, 0.36-0.73), but not for those with planned early docetaxel (HR=0.90; 95% CI, 0.62-1.31).

“There is a delay in progression with an improvement in overall survival, but there is toxicity,”  cautioned study presenter Christopher Sweeney, MBBS, a medical oncologist at the Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute. “Ezalutamide actually increased the docetaxel-related toxicity.”

Olaratumab Flops in Phase 3 for Advanced Soft Tissue Sarcomas (Abstract LBA3)

Despite encouraging survival data in the previous phase 1b/2 trial, olaratumab in combination with doxorubicin failed to improve survival in patients with advanced soft tissue sarcomas in the phase 3 ANNOUNCE trial. Olaratumab in combination with doxorubicin was granted accelerated approval in 2016, but in light of the ANNOUNCE trial results, olaratumab is in the process of being withdrawn from the market.

No clear reason was offered for the failure of olaratumab in the phase 3 trial, but a few possibilities were floated, such as the control arm having a particularly high OS and not limiting study entry to treatment-naïve patients.

Offering a partial explanation for the initial survival benefit seen in the early-phase trial, study discussant Jaap Verweij, MD, PhD, Erasmus University Medical Center, said, “A critical issue in phase 2 studies, certainly in a group of diseases as heterogenous as soft tissue sarcomas, are small numbers of patients.”

Olaparib Hits its Target in BRCA-Positive Metastatic Pancreatic Cancer (Abstract LBA4)

Maintenance therapy with olaparib, a PARP inhibitor, after first-line, platinum-based chemotherapy extended progression-free survival (PFS) for patients with germline BRCA-positive metastatic pancreatic cancer, according to the results of the phase 3 POLO trial. Final OS results are still maturing.

The trial included metastatic pancreatic cancer patients with a BRCA1 or BRCA2 germline mutation who received chemotherapy for at least 16 months and then were randomly assigned maintenance therapy with either olaparib or placebo.

The median PFS was 7.4 months for the olaparib arm and 3.8 months for the placebo arm, resulting in a 47% reduced risk of progression for patients receiving olaparib (HR=0.53; 95% CI, 0.35 – 0.82; P=0.0038).

The objective response rate was 23.1% (18 of 78 patients) for the olaparib arm and 11.5% (6 of 52 patients) for the placebo arm, with two patients on olaparib achieving a complete response; both complete responses are ongoing. The median duration of response was 24.9 months for the olaparib arm and 3.7 months for the placebo arm.

“We conclude that a strategic approach of first-line, platinum-based chemotherapy followed by maintenance olaparib treatment should become a new standard of care for patients with metastatic pancreatic cancer who have a germline BRCA mutation,” said the study presenter Hedy Kindler, MD, Professor of Medicine, University of Chicago Medicine.

by Christina Bennett, MS

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