A new research study called “Effect of bevacizumab in advanced low grade serous ovarian cancer: Data from the MITO 22 trial” published in Gynaecological Oncology gives information on the effectiveness of bevaziumab in the treatment of low-grade serous carcinoma.
In this paper researchers looked at the effect of adding bevacizumab (Avastin) to chemotherapy treatment for low-grade serous carcinoma at the time of diagnosis, and following a first recurrence, compared to chemotherapy alone.
The study used data from people enrolled in the retrospective observational MITO 22 study in Italy who were diagnosed with stage I to IV low-grade serous carcinoma between 2014 and 2018.
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What was the impact of including bevacizumab as part of the initial treatment of low-grade serous carcinoma?
Researchers found that people in the study receiving bevacizumab and chemotherapy at the time of diagnosis had longer progression free survival (time taken for cancer to recur (return) or progress (grow)) than those who received chemotherapy alone. The difference was most pronounced in people with residual disease (visible cancer) following surgery. People with residual disease receiving bevacizumab and chemotherapy were also more likely to experience tumour shrinkage compared to those who had chemotherapy alone.
Information about participants:
95 people with stage III/IV low-grade serous carcinoma were included in this part of the study – all of whom received chemotherapy treatment as part of their initial low-grade serous treatment (mainly 6 cycles carbo/taxol). Most people started treatment after surgery (primary debulking surgery) instead of treatment before surgery (neo-adjuvant treatment with interval debulking surgery). Just 4 people received any hormonal maintenance therapy as part of their primary treatment. When bevacizumab was used it was administered every three weeks.
The median progression free survival was 48 months in those receiving bevacizumab and chemotherapy (30 people) compared to 23 months for those who did not have bevacizumab (65 people).
Findings in people with no residual (visible) cancer following surgery:
When researchers looked at people who had no residual cancer following surgery – the median progression free survival was not met in the bevacizumab and chemotherapy group (meaning at the study cut of date of Jan 2021 less than half of the 22 people in this category had experienced a recurrence) and was found to be 48 months in the no bevacizumab group (56 people).
Findings in people with visible cancer following surgery:
When researchers looked at people with residual disease following surgery – the median progression free survival was 32 months in the bevacizumab with chemotherapy group (8 people) and 10 months in the group who had chemotherapy only (30 people).
100% of people who received bevacizumab had tumour shrinkage (4 complete responses and 4 partial responses) compared to 63% of people who did not receive bevacizumab (10 complete responses and 9 partial responses). Of the remainder in the no bevacizumab group, 13% (4 people) had stable disease while 23% (7 people) experienced progression despite chemotherapy treatment.
What was the impact of including bevacizumab as part of treatment for the first recurrence?
Researchers found that people in the study receiving bevacizumab and chemotherapy as part of their first recurrence treatment had a longer progression free survival and were more likely to experience tumour shrinkage than people who received chemotherapy alone.
Information about participants:
49 people were included in this part of the study. Everyone received carboplatin/paclitaxel chemotherapy at the time of diagnosis with low-grade serous carcinoma (without bevacizumab) and chemotherapy as part of their first recurrence treatment. Participants initial stage at diagnosis ranged from stage I to IV – most were stage III. The most commonly prescribed chemotherapy treatment for recurrence was carboplatin/pegylated liposomal doxorubicin followed by carboplatin/gemcitabine. Approximately one third of participants had surgery before starting recurrence treatment. None of the participants received hormonal therapy (such as letrozole).
The median progression free survival was 37 months for the group of participants receiving bevacizumab as part of their recurrence treatment (16 people) and 11 months in those who only received chemotherapy without bevacizumab (33 people).
In people who had visible cancer before medical treatment – 92% of those who received bevacizumab experienced tumour shrinkage (5 complete responses and 7 partial responses) with 1 person experiencing stable disease (no growth). In the chemotherapy only group, 41% of people experienced tumour shrinkage (3 complete responses and 9 partial responses), 35% had stable disease (10 people) and 24% continued to experience tumour growth despite chemotherapy treatment.
This paper adds to previous research on the effectiveness of bevacizumab for recurrent low-grade serous carcinoma however, it is the information on its use in newly diagnosed people that we believe is the most significant part of the study.
While hormonal therapy is commonly used in North America and Australasia in the frontline (newly diagnosed) low-grade serous setting, in Europe bevacizumab is more common. Several studies have demonstrated the effect of hormonal therapy, but until now, evidence for the use of bevacizumab in the frontline setting has been limited.
While we note that though the median progression free survival in the bevacizumab group was less than that found in a 2017 study of hormonal maintenance therapy it is not possible to draw any conclusions as to which treatment is better due to differences in the study participants.
Ultimately, we think this study will encourage future research to compare bevacizumab and chemotherapy with hormonal therapy (on it’s own or following chemotherapy) to determine which treatment works best in newly diagnosed low-grade serous carcinoma.
This study also adds to a body of research suggesting that outcomes in people receiving chemotherapy alone in newly diagnosed low-grade serous carcinoma are probably not as good as when chemotherapy is used in combination (with bevacizumab or prior to hormonal maintenance therapy).
Published: 8th July 2023
This article has been approved by study authors Dr Sandro Pignata and Dr Lucia Musacchio