PLATFORM Trial Analysis for Durvalumab Demonstrates Patient Subset Gained Radiological Response

No survival advantage was observed with durvalumab use in the PLATFORM clinical trial, but a patient subgroup was observed to have a radiological response.

The Planning Treatment for Oesophago-gastric Cancer: A Maintenance Therapy Trial (PLATFORM) is a prospective, multicenter, phase 2 trial evaluating multiple maintenance therapies in patients with locally advanced or metastatic HER2-positive or HER2-negative esophageal-gastric carcinoma.1 The therapies being evaluated are durvalumab, a monoclonal antibody; capecitabine, a chemotherapy drug; rucaparib, a poly (ADP-ribose) polymerase inhibitor; and ramucirumab, a monoclonal antibody that targets VEGFR2.2 The study was designed to randomize patients into 5 groups: A1, surveillance; A2, capecitabine; A3, durvalumab; A4, durvalumab plus rucaparib; and A5, capecitabine plus ramucirumab.1 The study’s primary end point was progression-free survival (PFS) from randomization to disease progression or death. The study’s secondary end points were time to objective response rate (ORR), overall survival (OS), time-to-treatment failure (TTF), and treatment toxicity.

Treatment will be offered to patients until their disease progresses, unacceptable toxicity occurs, or the patient decides to withdraw from treatment. Patient review was performed every 4 weeks for the surveillance group and every 3 to 4 weeks in the maintenance therapy groups. Computed tomography was used every 12 weeks to assess response to therapy in all patients.1

At the 2021 American Society of Clinical Oncology Annual Meeting, Fong and colleagues presented the results of an analysis of durvalumab (A3) versus surveillance (A1). Patients in this analysis received platinum-based chemotherapy for 18 weeks. After they responded to treatment or achieved stable disease, they were randomized into study groups according to HER2 status. The participants were stratified according to performance status and disease extent (locally advanced vs metastatic disease).

There were 205 patients randomized into groups A1 (100 patients) and A3 (105 patients) with a median follow-up of 24.2 months. Group A3 was closed prematurely because of withdrawal of industry support. PFS was 3.2 months for A1 and 4.7 months for A3. Analysis revealed a median OS of 11.4 months for A1 and 11.3 months for A3. TTF was 3.2 months for A1 and 3.5 months for A3. In group A3, 2 patients had a complete response and 4 had partial responses, giving this group an ORR of 6%. No patients in A1 had any radiological responses. PD-L1 combined positive score results were used for survival analysis. These results were available for 76 patients in group A1 and 77 patients in group A3, and scores were comparable between the 2 groups. There were 101 patients in the A3 group available for the safety analysis. Treatment toxicity evaluation revealed 18% of the A3 patients had grade ≥3 treatment-related adverse events.

The subgroup analysis demonstrating a radiological response in this group may indicate further investigation is warranted.

Source: Fong C, Patel B, Peckitt C, et al. Maintenance durvalumab after first-line platinum-based chemotherapy in advanced oesophago-gastric (OG) adenocarcinoma: results from the PLATFORM trial. J Clin Oncol. 2021;39(suppl_15):abstr 4015.

References

  1. ClinicalTrials.gov. Planning treatment for oesophago-gastric cancer: a maintenance therapy trial (PLATFORM). Updated February 21, 2020. https://clinicaltrials.gov/ct2/show/NCT02678182. Accessed October 7, 2021.
  2. Cancer Research UK. A trial of additional treatment for oesophageal cancer and stomach cancer (PLATFORM). Updated September 15, 2021. www.cancerresearchuk.org/about-cancer/find-a-clinical-trial/a-trial-of-additional-treatment-for-oesophageal-cancer-and-stomach-cancer-platform. Accessed October 7, 2021.

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