Abscopal effect in a patient with malignant pleural mesothelioma treated with palliative radiotherapy and pembrolizumab

Our plain-English summary of Abscopal effect in a patient with malignant pleural mesothelioma treated with palliative radiotherapy and pembrolizumab, by W.A. Mampuya, H. Bouchaab, N. Schaefer, et al (Clinical and Translational Radiation Oncology, 2021).

The study

• Authors: W.A. Mampuya, H. Bouchaab, N. Schaefer, R. Kinj, S. La Rosa, I. Letovanec, M. Ozsahin, J. Bourhis, G. Coukos, S. Peters, F.G. Herrera
• Journal: Clinical and Translational Radiation Oncology
• Published: 2021;27:85-88
• Type of article: Case report
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The abscopal effect describes the ability of locally administered radiotherapy to induce systemic antitumor effects. Although mentioned for the first time in the 1950s, records of abscopal effects, considered to be immune-mediated, are scarce with radiotherapy alone. However, with the continued development and use of immunotherapy, reports on the abscopal effect have become increasingly frequent during the last decade. Here, we report a patient with advanced malignant pleural mesothelioma who had progressive disease while on the anti-PDL1 inhibitor pembrolizumab and showed an abscopal response after palliative radiotherapy.

© 2020 The Author(s).

In plain English

Doctors at Lausanne University Hospital, Switzerland, reported one 72-year-old man with occupational asbestos exposure who was diagnosed with malignant pleural mesothelioma. A CT scan also showed calcified pleural plaques. He had four cycles of carboplatin, pemetrexed and bevacizumab, then three maintenance cycles of pemetrexed and bevacizumab, after which side effects ended chemotherapy. The patient then received pembrolizumab, which the authors describe as an anti-PD-L1 inhibitor. In September 2017, after 20 cycles, the disease progressed. While pembrolizumab continued, palliative radiotherapy (30 Gy in 10 fractions) was given to a lesion beside the mediastinum. The right pleural lesions were left out of the treatment area and received less than 0.5 Gy. Three months later, scans showed partial response in both the irradiated and the unirradiated lesions. The authors interpreted this as an abscopal effect, meaning tumor shrinkage away from the treated site. Five years after diagnosis, the patient remained clinically and radiologically stable. The authors concluded that this effect may occur in such patients but is a rare observation that does not justify routine use, and that clinical trials are needed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report (one patient)
• Who was studied: One 72-year-old male patient with hypertension, ischemic heart disease and chronic obstructive pulmonary disease. He was admitted to Lausanne University Hospital, Switzerland, in April 2015 and diagnosed with malignant pleural mesothelioma (staged T3 N2 M0).
• Exposure: Occupational exposure to asbestos; the fiber type and job are not stated
• Main results:
  • At admission, a chest CT scan of the patient showed a pleural effusion, calcified pleural plaques and mediastinal pleural thickening
  • After 4 cycles of carboplatin, pemetrexed and bevacizumab, a CT scan showed partial response
  • The patient then had three cycles of maintenance chemotherapy with pemetrexed and bevacizumab, with stable disease reported
  • After the maintenance cycles, the patient had grade 3 oral mucositis and watering eyes and grade 2 nephrotoxicity, and chemotherapy was stopped
  • The patient started pembrolizumab in July 2016; the authors describe it as an anti-PD-L1 inhibitor. In September 2017, after 20 cycles, scans showed progressive enlargement of the right pleural and paramediastinal lesions.
  • While pembrolizumab continued, 30 Gy in 10 fractions was given to the paramediastinal lesion. The right pleural lesions were not included in the radiotherapy volume.
  • According to the authors, the unirradiated pleural lesions received less than 0.5 Gy
  • Three months after radiotherapy, a PET/CT scan showed partial response in both the irradiated paramediastinal lesion and the unirradiated right pleural lesions
  • A later retropharyngeal metastasis was positive for PD-L1 in about 10% of tumor cells. It was irradiated in April 2018.
  • By July 2018 the paramediastinal lesion and the retropharyngeal mass were in complete remission, and the right pleural lesion continued to shrink
  • At 24 months after radiotherapy, the right pleural lesion's SUVmax (a PET scan uptake measure) had declined to 2.8
  • Five years after diagnosis, the patient remained clinically and radiologically stable and had received the 70th cycle of pembrolizumab in November 2020
• The authors' conclusion: The authors concluded that an abscopal effect may be observed in malignant pleural mesothelioma treated with anti-PD-L1 therapy and radiotherapy together. They added that this is a rare observation that does not justify use in routine clinical practice, and that robust clinical trials are required. They stated that, as far as they know, this is the first abscopal effect in malignant pleural mesothelioma reported in the literature.
• Limitations the authors state:
  • The authors note that this is a rare observation and that hypothesis-testing clinical trials are needed

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Palliative Care, Pembrolizumab (Keytruda), Immunotherapy.

Related studies

• First-ever Abscopal Effect after Palliative Radiotherapy and Immuno-gene Therapy for Malignant Pleural Mesothelioma — A.R. Barsky, K.A. Cengel, et al. (2019)
• Radiation Induced Abscopal Effect in a Patient With Malignant Pleural Mesothelioma on Pembrolizumab — R. Rittberg, E. Chan, et al. (2022)
• Re-evaluating the role of palliative radiotherapy in malignant pleural mesothelioma — P. Jenkins, R. Milliner, et al. (2011)
• High-dose palliative radiotherapy for malignant pleural mesothelioma — F. Foroudi, J.G. Smith, et al. (2017)
• Initial clinical experience treating patients with palliative radiotherapy for malignant pleural mesothelioma on the HalcyonTM linear accelerator — A.R. Barsky, M.M. Kim, et al. (2020)
• Analysis of the effect of radiotherapy on malignant pleural mesothelioma when given on adjuvant or palliative basis — H.A. El Hossieny, F. Aboulkasem, et al. (2010)

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