PARP inhibitors were one of the great clever tricks of modern cancer therapy. They exploit a weakness in tumors that already struggle to repair DNA, especially those with BRCA-related or homologous recombination defects. Block PARP, pile up damage, and the cancer cell may finally collapse under its own paperwork. Elegant. Slightly vindictive. Very satisfying.
The trouble is that cancer, being a deeply annoying student of evolutionary biology, learns. Many ovarian tumors eventually become resistant to PARP inhibitors. They find backup routes, restore bits of DNA repair, stabilize replication forks, or simply wriggle around the blockade like a raccoon defeating a trash-can lid [2,4,5]. Once that happens, doctors have not had a lavish menu of maintenance options after another round of platinum chemotherapy. In fact, recent expert review pieces make the point rather plainly: beyond bevacizumab, choices are thin [5].
That is why this paper caught my eye. Sachdeva and Tan discuss the KGOG 3056/NIRVANA-R trial, which tested a daring idea in platinum-sensitive recurrent ovarian cancer: go back to PARP inhibition, but this time pair niraparib with bevacizumab after prior PARP exposure [1].
Why add bevacizumab to the party?
Bevacizumab is an anti-angiogenic drug. Translation: it interferes with the tumor’s efforts to build new blood vessels, which is rather like cutting off the catering and pretending the banquet will continue as normal. The biological hope is that starving the tumor’s blood supply changes its environment in ways that make DNA repair harder and PARP inhibition more effective again [3].
In NIRVANA-R, 44 patients with platinum-sensitive recurrent ovarian cancer, all previously treated with a PARP inhibitor, received niraparib plus bevacizumab as maintenance therapy. The headline result was a 6-month progression-free survival rate of 68%, with a median progression-free survival of 11.5 months [1]. That is not a cure. It is not even a final answer. But in this setting, it is enough to make experienced oncologists put down their coffee and read the methods section.
The signal looked particularly better in patients who had done well with their most recent platinum chemotherapy, especially those with a complete response or a longer treatment-free interval [1]. That makes clinical sense. Tumors that still behave as if they fear platinum may still have exploitable cracks in their DNA-repair armor.
The ghost of PARP past
We do have a comparison point, though it must be handled gently. In the randomized OReO/ENGOT-ov38 trial, olaparib rechallenge after prior PARP inhibitor exposure produced only modest benefit: median progression-free survival was 4.3 versus 2.8 months in BRCA-mutated disease, and 5.3 versus 2.8 months in BRCA wild-type disease [5,6]. Useful? Yes. Triumphal? Not quite.
That is why NIRVANA-R is intriguing. The numbers look better. But before anybody starts composing victory speeches, this was a single-arm phase 2 study, not a head-to-head randomized trial [1]. Cross-trial comparison is a dangerous sport. It has injured many perfectly respectable oncologists.
Still, the idea fits a larger trend. Combination strategies are now the main avenue for dealing with PARP resistance, whether by adding anti-angiogenic therapy, ATR inhibitors, WEE1 inhibitors, or other agents that make cancer cells feel less smug about their DNA repair options [2,4]. One first-line study of niraparib plus bevacizumab, the OVARIO trial, also suggested that the pairing can be active and tolerable in ovarian cancer, which adds a little biological and clinical backbone to the rechallenge concept [7].
What this could mean outside the conference hall
If these findings hold up in larger randomized studies, the real-world value is pretty clear. Some patients with recurrent ovarian cancer might get a meaningful stretch of disease control without returning immediately to the full carousel of more chemotherapy. That matters. Time with cancer under control, and without fresh cytotoxic misery every few weeks, is not a footnote. It is life.
The deeper appeal is historical. Cancer medicine has often advanced by revisiting old drugs with smarter timing and better company. We old-timers remember when interferon was going to solve everything. It did not. But every so often, the sequel really is better written.
For now, the sober view is this: NIRVANA-R suggests that PARP inhibitor rechallenge is not absurd, and in selected patients it may be genuinely useful, especially when paired with bevacizumab. The joke, as ever, is that cancer biology remains absurdly complicated. The comfort is that researchers keep finding new ways to bother it back.
References
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Sachdeva M, Tan DSP. Returning to PARP inhibition: Rechallenge with Bevacizumab in Ovarian Cancer. Clin Cancer Res. 2025. DOI: https://doi.org/10.1158/1078-0432.CCR-26-0534
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Zou Y, Zhang H, Chen P, et al. Clinical approaches to overcome PARP inhibitor resistance. Mol Cancer. 2025;24:156. DOI: https://doi.org/10.1186/s12943-025-02355-1. PMCID: https://pmc.ncbi.nlm.nih.gov/articles/PMC12123805/
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Zielli T, Labidi-Galy I, Del Grande M, et al. The clinical challenges of homologous recombination proficiency in ovarian cancer: from intrinsic resistance to new treatment opportunities. Cancer Drug Resist. 2023;6(3):499-516. DOI: https://doi.org/10.20517/cdr.2023.08. PMCID: https://pmc.ncbi.nlm.nih.gov/articles/PMC10571062/
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Lee M, Lim MC, Choi CH, et al. An overview of PARP resistance in ovarian cancer from a molecular and clinical perspective. Cancer Drug Resist. 2022;5:637-646. DOI: https://doi.org/10.20517/cdr.2021.146
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Mukherjee UA, Miller RE, Ledermann JA. Controversies and clinical unknowns in the use of PARP inhibitors in ovarian cancer. Ther Adv Med Oncol. 2025;17:17588359251343973. DOI: https://doi.org/10.1177/17588359251343973
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Pujade-Lauraine E, Selle F, Scambia G, et al. Maintenance olaparib rechallenge in patients with platinum-sensitive relapsed ovarian cancer previously treated with a PARP inhibitor (OReO/ENGOT-ov38): a phase IIIb trial. Ann Oncol. 2023;34(12):1152-1164. DOI: https://doi.org/10.1016/j.annonc.2023.09.3110
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Hardesty MM, Krivak TC, Wright GS, et al. A phase 2 trial of niraparib plus bevacizumab maintenance therapy following first-line platinum-based chemotherapy with bevacizumab in advanced ovarian cancer: final analysis and overall survival results from OVARIO. Gynecol Oncol. 2025;199:96-102. DOI: https://doi.org/10.1016/j.ygyno.2025.06.014
Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.