The Role of Biomarker Testing in Ovarian Cancer

Bradley J. Monk, MD, FACS, FACOG

The indentification of predictive and prognostic biomarkers has become increasingly important in the diagnosis and treatment of ovarian cancers (OCs), especially as newer biomarkers emerge.

OC is the fifth leading cause of cancer mortality in women in the United States.^1-3 Despite many significant advances in treatment, more than 70% of patients with stage III to IV OC will have a recurrence within the first 5 years after diagnosis, which is often fatal.⁴

There is no single best treatment algorithm for ovarian cancer.⁴ Treatment decisions, which become increasingly complex with disease progression, are informed by several patient-specific clinicopathologic parameters and genomic results.⁴ For most patients, surgery for staging and cytoreduction followed by platinum-based systemic chemotherapy with or without targeted biological agents with induction therapy, or as maintenance treatment, is the frontline standard of care.^3-6

Recurrence results “in a cycle of surgeries and additional rounds of chemotherapy,” Bradley J. Monk, MD, FACS, FACOG, said in an interview with Targeted Therapies in Oncology™, adding that, “Biomarker testing can help predict the potential magnitude of a therapeutic effect in patients with OC.” Monk is a professor of gynecologic oncology at Arizona Oncology (US Oncology Network) and University of Arizona College of Medicine, the medical director of the gynecologic program at US Oncology Research, and a codirector at GOG Partners.

Biomarkers for Treatment Choice

There are several potential therapeutic targets in gynecological cancers, including tumor-intrinsic signaling pathways, homologous recombination deficiency (HRD), angiogenesis, immunologic factors, and hormone receptors.⁷

Genetic tests available for evaluating BRCA and HRD status are shown in the TABLE^8-15. In addition to commercial tests, some medical/research institutions have their own assays for evaluating many of these genes.^16-18

“Guidelines recommend biomarker testing in all patients with OC,” Monk said. “OC biomarkers can be analyzed using single-gene tests or as part of a multigene panel, and BRCA1/2 testing was included in multigene panels beginning in 2013.” However, one study showed only 30% of patients diagnosed with OC between 2013 and 2014 received genetic testing.¹⁹

VEGF

VEGF, a vascular permeability factor, is a key regulator of physiological and pathological angiogenesis and a major contributor to tumorigenesis. Patients with OC have elevated VEGF levels, which contribute to the accumulation of ascites. In an analysis of tumor VEGF levels in 110 patients with OC, high VEGF was associated with worse survival outcomes (P < .01).^20,21 The fi rst and most studied anti-VEGF agent, bevacizumab (Avastin), led to improvements in overall survival (OS) in patients with higher-stage disease, greater disease burden, and ascites.^22-25 Although no molecularly defi ned biomarker that predicts benefi t from bevacizumab has been described, high tumor expression of colocalized MET/VEGFR-2 was associated with significantly reduced OS (HR, 2.00; 95% CI, 1.08-3.72; P = .03) and the VEGFR2 rs2305945 G/G variant was associated with worse progression-free survival (PFS).²⁶

BRCA1/2

Wild-type breast cancer 1 (BRCA1) and BRCA2 oncogenes are critical for DNA repair by the homologous recombination pathway.²⁷ Therefore, deletions or mutations in these genes causes genomic instability and predisposes affected individuals to familial breast cancer and OC.^27,28 Between 14% and 15% of all epithelial OCs have germline BRCA1/2 mutations, but the rate can be as high as 22.6% in high-grade serous OC, plus 6% due to somatic mutations.^29-31 OCs with BRCA1/2 mutations are especially susceptible to agents that induce DNA double-strand breaks and DNA interstrand crosslinks, such as platinum compounds (eg, cisplatin and carboplatin) and PARP inhibitors.²⁰ For patients with BCRA1/2-mutated OC who have not received bevacizumab, maintenance with olaparib (Lynparza) or niraparib (Zejula) increases median PFS.^32,33 The addition of olaparib to bevacizumab maintenance in patients who received bevacizumab up front also increases median PFS.³⁴ Survival benefi t has been maintained long term, with extended results from the PAOLA-1 trial (NCT02477644) showing 5-year OS rates in patients with advanced OC and a BRCA mutation of 73.2% with the olaparib and bevacizumab combination compared with 53.8% with placebo (HR, 0.60; 95% CI, 0.39-0.93).³⁵

DNA Damage Response Genes

After BRCA1/2 mutations, defi ciencies in the mismatch repair (MMR) system are the most common cause of hereditary OC.³⁶ The MMR system, which is a complex pathway of 7 genes, corrects mutations arising during DNA replication or damage, playing a crucial role in maintaining genome stability.³⁷

Robert L. Coleman, MD, FACOG, FACS

Another DNA damage response gene is CHEK2, which encodes a protein kinase activated in response to DNA damage and interacts with BRCA1, promoting cellular survival.³⁸ The missense variant of CHEK2, I157T, is signifi cantly associated with ovarian cystadenomas (odds ratio [OR], 1.7; P = .005), borderline ovarian tumors (OR, 2.6; P = .002), and low-grade invasive cancers (OR, 2.1; P = .04) but not high-grade OC (OR, 1.0).³⁸

Homologous recombination repair genes

Homologous recombination deficient cells cannot repair DNA double-strand breaks, making them reliant on the single-strand repair mechanism. This can be exploited by the use PARP inhibitors. The PARP enzyme is needed to repair single-strand DNA breaks, so PARP inhibition leads to an accumulation of double-strand breaks. The use of PARP inhibitors in patients with homologous recombination deficient tumors leads to tumor cell death by a phenomenon called synthetic lethality.²⁹ Both niraparib and the combination of bevacizumab/olaparib are effective for the treatment of patients with HRD.^35,39

Genetic and epigenetic alterations in homologous recombination repair (HRR) genes, leading to defective DNA repair, are present in approximately half of epithelial OCs.²⁹ HRD can also be induced by the overexpression of specific microRNAs.²⁹ Mutations in some HRR genes, including BRCA1 and BRCA2, as well as ATM, ATR, BARD1, BLM, BRIP1, CHEK1, CHEK2, FAM175A, MRE11A, NBN, PALB2, RAD51C, RAD51D, RBBP8, SLX4, and XRCC2, are associated with platinum sensitivity and prolonged survival.^29,40,41

Loss of heterozygosity

Loss of heterozygosity (LOH) is a common form of chromosome instability, in which a heterozygous somatic cell becomes homozygous due to the loss of an allele.²⁹ LOH is also correlated with an increased response to platinum-based chemotherapy.42 Response to therapy (platinum and PARP inhibitors) is influenced by genomic instability caused by chromosomal alterations, nucleotide substitutions, insertions, and deletions that accumulate in the absence of DNA repair due to DNA damage response gene mutations (germline and somatic).^29,43,44

These biomarkers can be used in counseling patients about the magnitude of benefit that they may receive from using a PARP inhibitor for maintenance therapy because patients who are platinum sensitive with no BRCA mutation but are HRD positive, LOH high, or have a germline or somatic mutation in other HRR genes have an even stronger benefit from maintenance PARP inhibition than those who are HRD negative and LOH low with no HRR gene mutations.²⁹ Patients who are weighing the benefi ts of using other maintenance therapy options such as bevacizumab or discussing whether the adverse effect profiles are worth the added benefit may find this information useful.

Finally, the use of these biomarkers may play a role in the near future in expanding the number of patients who could receive— and be expected to benefit from—PARP inhibition, either in the up-front setting before the patient’s platinum-sensitivity status is known or in platinum-resistant patients.²⁹

Microsatellite instability/stable and PD-L1

A high proportion of OCs with germline MMR mutations (MSH2, MSH6, MLH1, PMS2) demonstrate microsatellite instability (MSI).⁷ MSI is predictive o f sensitivity to immune checkpoint inhibitors, such as PD-1 or PD-L1.⁴⁵ Therefore, the use of these agents is becoming increasingly popular in the treatment of various cancers because it is associated with longer survivals compared with chemotherapy and targeted therapy.^45,46 Pembrolizumab (Keytruda), for example, has a tumor-agnostic indication for the treatment of patients with unresectable or metastatic cancer with MSI high or MMR deficiency.⁴⁷ However, a recent quantitative meta-analysis showed that PD-1/PD-L1 inhibitors alone have limited effi cacy for OC (combined objective response rate, 19%; 95% CI, 13%-27%), whereas combination regimens with chemotherapy should be studied further (combined objective response rate, 36%; 95% CI, 24%-51%).⁴⁵

Prognostic Biomarkers

As is the case with several other cancers, TP53 is frequently mutated i n OC; in fact, almost all (97%) high-grade serous OCs have mutations in TP53.⁴⁸ Although many studies have investigated TP53 as a biomarker in OC, there are still disputes over its prognostic and predictive values.⁴⁸ Another candidate prognostic biomarker is CKB, a cytosolic isoform of creatine kinase. Due to its high expression in early-stage OC, CKB is a potential biomarker for the early detection of OC.²⁰

Diagnostic Biomarkers

The survival rates for early-stage (I and II) OC are much higher (70%-90%) than for later-stage (III and IV) OC (30%). Furthermore, in the absence of an effective screening strategy, up to 80% of OCs are diagnosed in the late stage. This gives a strong rationale for OC screening.³¹

Currently, OC screening is done using a combination of blood-based biomarkers—notably, cancer antigen 125 (CA125, also called mucin 16 [MUC16]) and human epididymis protein 4 (HE4)—and transvaginal ultrasound imaging.49,50 Although CA125 and HE4 are the best available diagnostic biomarkers for OC, they have insufficient sensitivity and specifi city. Therefore, the development of additional diagnostic biomarkers for OC is needed.⁴⁹

Biomarkers of Interest for the Future

In preliminary studies, circulating tumor DNA (ctDNA) was detected in blood and cervical secretions from 55% of patients with early-stage OC, including in cases missed by CA125 testing alone. A more concentrated sample of ctDNA can be obtained from cervical material than from the peripheral blood, which may be critical for the detection of tumors less than 1 cm in diameter.^31,51 The recent development of a repetitive element aneuploidy sequencing system (RealSeq) to detect aneuploidy in ctDNA from as little as 3 pg of DNA in relatively small amounts of plasma may improve sensitivity for early-stage high-grade OCs with copy number abnormalities.⁵² Additionally, 2 clinical trials have further investigated biomarkers for OC (NCT01466049 and NCT00854399).^53,54

Takeaways

“Biomarker testing results, including HRD, BRCA, and defi cient MMR/MSI status, can help predict the potential magnitude of a therapeutic effect in patients with ovarian cancer,” Monk said. “Patient counseling is an important component of biomarker testing and is recommended as a fundamental aspect of care for women with ovarian cancer.”

In an interview with Targeted Therapies in Oncology™, Robert L. Coleman, MD, FACOG, FACS, chief scientifi c offi cer for US Oncology Research and codirector of GOG Partners, summarized the main takeaways from the past few years of OC biomarker research.

“The last provocative clinical trial to inform treatment [decision-making] for patients with OC was PAOLA-1,” Coleman said. “I have recommended and used bevacizumab as primary adjuvant therapy for several years, but the availability of olaparib [for] these patients whose tumors harbor HRD detected by a test changed my approach to maintenance therapy and to genomic testing. Previously my testing approach was to obtain tumor and germline testing for BRCA. Now I add HRD.

“I would also mention that the failure of immune checkpoint inhibitor trials in both primary and recurrent setting has removed that option except for those patients with MSI high or the rare case with high tumor mutational burden.”

_REFERENCES:

_{1. Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer statistics, 2022. CA Cancer J Clin. 2022;72(1):7-33. doi:10.3322/caac.21708}

_{2. Cancer stat facts: ovarian cancer. National Cancer Institute. Accessed August 29, 2022. https://seer.cancer.gov/statfacts/html/ovary.html}

_{3. Doubeni CA, Doubeni AR, Myers AE. Diagnosis and management of ovarian cancer. Am Fam Physician. 2016;93(11):937-944.}

_{4. Kurnit KC, Fleming GF, Lengyel E. Updates and new options in advanced epithelial ovarian cancer treatment. Obstet Gynecol. 2021;137(1):108-121. doi:10.1097/AOG.0000000000004173}

_{5. NCCN. Ovarian cancer, including fallopian tube cancer and primary peritoneal cancer. Version 4.2022. Accessed August 26, 2022. https://bit.ly/2Nr8vCu}

_{6. Foo T, George A, Banerjee S. PARP inhibitors in ovarian cancer: an overview of the practice-changing trials. Genes Chromosomes Cancer. 2021;60(5):385-397. doi:10.1002/gcc.22935}

_{7. Radu MR, Prădatu A, Duică F, et al. Ovarian cancer: biomarkers and targeted therapy. Biomedicines. 2021;9(6):693. doi:10.3390/biomedicines9060693}

_{8. Oncology. Ambry Genetics. Accessed September 6, 2022. https://bit.ly/3BiYQaI}

_{9. Comprehensive tumor profiling. Caris Life Sciences. Accessed September 6, 2022. https://bit.ly/3DqJALu}

_{10. FoundationOne CDx. Foundation Medicine. Accessed September 6, 2022. https://bit.ly/2v3SYjQ}

_{11. Breast/Gyn Panel. GeneDx. Accessed September 6, 2022. https://bit.ly/3BLt5bA}

_{12. Invitae Breast and Gyn Cancers Panel. Invitae. Accessed September 6, 2022. https://bit.ly/3QN4nMj}

_{13. Myriad genetic tests. Myriad Genetics. Accessed September 6, 2022. https://bit.ly/3BL3LT6}

_{14. MyChoice CDx Myriad HRD companion diagnostic test. Myriad Genetics. Accessed September 6, 2022. https://bit.ly/3qGujhR}

_{15. The MyRisk Hereditary Cancer Test helps you make the decisions that matter most. Myriad Genetics. Accessed September 6, 2022. https://bit.ly/3QK7iVX}

_{16. BROCA cancer risk panel. UW Medicine Laboratory Medicine & Pathology. Accessed September 6, 2022. https://bit.ly/3UhfCiU}

_{17. Cancer genetics and prevention. Dana-Farber Cancer Institute. Accessed September 6, 2022. https://bit.ly/3DCwWJc}

_{18. MSK-IMPACT: a targeted test for mutations in both rare and common cancers. Memorial Sloan Kettering Cancer Center. Accessed September 6, 2022. https://bit.ly/3DCwQ4i}

_{19. Kurian AW, Ward KC, Howlader N, et al. Genetic testing and results in a population-based cohort of breast cancer patients and ovarian cancer patients. J Clin Oncol. 2019;37(15):1305-1315. doi:10.1200/JCO.18.01854}

_{20. Atallah GA, Abd Aziz NH, Teik CK, Shafiee MN, Kampan NC. New predictive biomarkers for ovarian cancer. Diagnostics (Basel). 2021;11(3):465. doi:10.3390/diagnostics11030465}

_{21. Yamamoto S, Konishi I, Mandai M, et al. Expression of vascular endothelial growth factor (VEGF) in epithelial ovarian neoplasms: correlation with clinicopathology and patient survival, and analysis of serum VEGF levels. Br J Cancer. 1997;76(9):1221-1227. doi:10.1038/bjc.1997.537}

_{22. Burger RA, Brady MF, Bookman MA, et al; Gynecologic Oncology Group. Incorporation of bevacizumab in the primary treatment of ovarian cancer. N Engl J Med. 2011;365(26):2473-2483. doi:10.1056/NEJMoa1104390}

_{23. Perren TJ, Swart AM, Pfisterer J, et al; ICON7 Investigators. A phase 3 trial of bevacizumab in ovarian cancer. N Engl J Med. 2011;365(26):2484-2496. doi:10.1056/NEJMoa1103799}

_{24. Oza AM, Cook AD, Pfisterer J, et al; ICON7 trial investigators. Standard chemotherapy with or without bevacizumab for women with newly diagnosed ovarian cancer (ICON7): overall survival results of a phase 3 randomised trial. Lancet Oncol. 2015;16(8):928-936. doi:10.1016/S1470-2045(15)00086-8}

_{25. Tewari KS, Burger RA, Enserro D, et al. Final overall survival of a randomized trial of bevacizumab for primary treatment of ovarian cancer. J Clin Oncol. 2019;37(26):2317-2328. doi:10.1200/JCO.19.01009}

_{26. Morgan RD, Ferreras C, Peset I, et al. c-MET/VEGFR-2 co-localisation impacts on survival following bevacizumab therapy in epithelial ovarian cancer: an exploratory biomarker study of the phase 3 ICON7 trial. BMC Med. 2022;20(1):59. doi:10.1186/s12916-022-02270-y}

_{27. Scully R, Livingston DM. In search of the tumour-suppressor functions of BRCA1 and BRCA2. Nature. 2000;408(6811):429-432. doi:10.1038/35044000}

_{28. Norquist BM, Garcia RL, Allison KH, et al. The molecular pathogenesis of hereditary ovarian carcinoma: alterations in the tubal epithelium of women with BRCA1 and BRCA2 mutations. Cancer. 2010;116(22):5261-5271. doi:10.1002/cncr.25439}

_{29. Arend R, Martinez A, Szul T, Birrer MJ. Biomarkers in ovarian cancer: to be or not to be. Cancer. 2019;125(suppl 24):4563-4572. doi:10.1002/cncr.32595}

_{30. Pal T, Permuth-Wey J, Betts JA, et al. BRCA1 and BRCA2 mutations account for a large proportion of ovarian carcinoma cases. Cancer. 2005;104(12):2807-2816. doi:10.1002/cncr.21536}

_{31. Bast RC Jr, Lu Z, Han CY, et al. Biomarkers and strategies for early detection of ovarian cancer. Cancer Epidemiol Biomarkers Prev. 2020;29(12):2504-2512. doi:10.1158/1055-9965}

_{32. González-Martin A, Pothuri B, Vergote I, et al; PRIMA/ENGOT-OV26/GOG-3012 Investigators. Niraparib in patients with newly diagnosed advanced ovarian cancer. N Engl J Med. 2019;381(25):2391-2402. doi:10.1056/NEJMoa1910962}

_{33. Moore K, Colombo N, Scambia G, et al. Maintenance olaparib in patients with newly diagnosed advanced ovarian cancer. N Engl J Med. 2018;379(26):2495-2505. doi:10.1056/NEJMoa1810858}

_{34. Ray-Coquard I, Pautier P, Pignata S, et al; PAOLA-1 Investigators. Olaparib plus bevacizumab as first-line maintenance in ovarian cancer. N Engl J Med. 2019;381(25):2416-2428. doi:10.1056/NEJMoa1911361}

_{35. Ray-Coquard IL, Leary A, Pignata S, et al. Final overall survival (OS) results from the phase III PAOLA- 1/ENGOT-ov25 trial evaluating maintenance olaparib (ola) plus bevacizumab (bev) in patients (pts) with newly diagnosed advanced ovarian cancer (AOC). Ann Oncol. 2022;33(suppl 7):S1396-SS397. doi:10.1016/j.annonc.2022.08.025}

_{36. Xiao X, Melton DW, Gourley C. Mismatch repair deficiency in ovarian cancer -- molecular characteristics and clinical implications. Gynecol Oncol. 2014;132(2):506-512. doi:10.1016/j.ygyno.2013.12.003}

_{37. Baretti M, Le DT. DNA mismatch repair in cancer. Pharmacol Ther. 2018;189:45-62. doi:10.1016/j.pharmthera.2018.04.004}

_{38. Szymanska-Pasternak J, Szymanska A, Medrek K, et al. CHEK2 variants predispose to benign, borderline and low-grade invasive ovarian tumors. Gynecol Oncol. 2006;102(3):429-431. doi:10.1016/j.ygyno.2006.05.040}

_{39. Chan JK, Liang SY, Kapp DS, et al. Selecting new upfront regimens for advanced ovarian cancer with biomarker guidance. Gynecol Oncol. 2020;159(3):604-606. doi:10.1016/j.ygyno.2020.09.017}

_{40. Pennington KP, Walsh T, Harrell MI, et al. Germline and somatic mutations in homologous recombination genes predict platinum response and survival in ovarian, fallopian tube, and peritoneal carcinomas. Clin Cancer Res. 2014;20(3):764-775. doi:10.1158/1078-0432.CCR-13-2287}

_{41. Norquist BM, Brady MF, Harrell MI, et al. Mutations in homologous recombination genes and outcomes in ovarian carcinoma patients in GOG 218: an NRG Oncology/Gynecologic Oncology Group Study. Clin Cancer Res. 2018;24(4):777-783. doi:10.1158/1078-0432.CCR-17-1327}

_{42. Telli ML, Timms KM, Reid J, et al. Homologous recombination deficiency (HRD) score predicts response to platinum-containing neoadjuvant chemotherapy in patients with triple-negative breast cancer. Clin Cancer Res. 2016;22(15):3764-3773. doi:10.1158/1078-0432.CCR-15-2477}

_{43. Coleman RL, Oza AM, Lorusso D, et al; ARIEL3 investigators. Rucaparib maintenance treatment for recurrent ovarian carcinoma after response to platinum therapy (ARIEL3): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2017;390(10106):1949-1961. doi:10.1016/S0140-6736(17)32440-6}

_{45. Mirza MR, Monk BJ, Herrstedt J, et al; ENGOT-OV16/NOVA Investigators. Niraparib maintenance therapy in platinum-sensitive, recurrent ovarian cancer. N Engl J Med. 2016;375(22):2154-2164. doi:10.1056/NEJMoa1611310}

_{46. Dudley JC, Lin MT, Le DT, Eshleman JR. Microsatellite instability as a biomarker for PD-1 blockade. Clin Cancer Res. 2016;22(4):813-820. doi:10.1158/1078-0432.CCR-15-1678}

_{47. Zhu J, Yan L, Wang Q. Efficacy of PD-1/PD-L1 inhibitors in ovarian cancer: a single-arm meta-analysis. J Ovarian Res. 2021;14(1):112. doi:10.1186/s13048-021-00862-5}

_{48. FDA approves Merck’s Keytrude (pembrolizumab) for adult and pediatric patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient cancer. News release. Merck. May 23, 2017. Accessed September 2, 2022. https://bit.ly/3S8YKch}

_{49. Zhang Y, Cao L, Nguyen D, Lu H. TP53 mutations in epithelial ovarian cancer. Transl Cancer Res. 2016;5(6):650-663. doi:10.21037/tcr.2016.08.40}

_{50. Mukama T, Fortner RT, Katzke V, et al. Prospective evaluation of 92 serum protein biomarkers for early detection of ovarian cancer. Br J Cancer. 2022;126(9):1301-1309. doi:10.1038/s41416-021-01697-z}

_{51. Giampaolino P, Foreste V, Della Corte L, Di Filippo C, Iorio G, Bifulco G. Role of biomarkers for early detection of ovarian cancer recurrence. Gland Surg. 2020;9(4):1102-1111. doi:10.21037/gs-20-544}

_{52. Ren AH, Fiala CA, Diamandis EP, Kulasingam V. Pitfalls in cancer biomarker discovery and validation with emphasis on circulating tumor DNA. Cancer Epidemiol Biomarkers Prev. 2020;29(12):2568-2574. doi:10.1158/1055-9965.EPI-20-0074}

_{53. Douville C, Cohen JD, Ptak J, et al. Assessing aneuploidy with repetitive element sequencing. Proc Natl Acad Sci U S A. 2020;117(9):4858-4863. doi:10.1073/pnas.1910041117}

_{54. New biomarkers evaluating ovarian cancer. ClinicalTrials.gov. Updated August 5, 2014. Accessed September 6, 2022. https://clinicaltrials.gov/ct2/show/NCT01466049}

_{55. Screening and identification of ovarian cancers. ClinicalTrials.gov. Updated March 3, 2009. Accessed September 6, 2022. https://clinicaltrials.gov/ct2/show/NCT00854399}