Feasibility of extension of platinum-free interval with weekly bolus topotecan and subsequent platinum retreatment outcomes in recurrent ovarian cancer

PARP Inhibitor in Platinum-Resistant Ovarian Cancer: Single-Center Real-World Experience

PURPOSE

Poly (ADP-ribose) polymerase inhibitors (PARPi) have proven efficacy in treatment of BReast CAncer (BRCA) gene mutation-positive platinum-sensitive ovarian cancers. There is paucity of data for their role in platinum-resistant ovarian cancer (PROC). We report here retrospective analysis of outcome of PARPi treatment in a group of patients including those of PROC.

PATIENTS AND METHODS

We analyzed all consecutive patients who received PARPi. The efficacy of PARPi monotherapy was assessed in patients with relapsed high-grade serous ovarian carcinoma with gBRCAm. The drug was procured through compassionate program. Drugs (olaparib and talazoparib) were provided in capsule form.

RESULTS

Between July 1, 2015, and June 30, 2019, 28 patients with ovarian cancer received PARPi. At the time of data censoring (September 30, 2019), four (14.3%) patients are still on treatment. Median age was 54.5 years (range, 39-75 years). Median number of previous lines of chemotherapy received was three (range, 1-6). Eleven platinum-sensitive patients received the drug as maintenance (five in complete response and six in partial response after chemotherapy), whereas 17 (60.7%) had platinum-resistant progressive disease while starting the drug. In PROC, objective response rate (complete response plus partial response) was 47%, median progression-free survival was 8.2 months (5.3-11.3), and overall survival was 14.9 months (11.2-18.5). No new side effects were observed.

CONCLUSION

This is the first study from India evaluating PARPi in platinum-resistant ovarian cancer. This study suggests that PARPi is a viable treatment option in patients with PROC with gBRCAm. This should be further evaluated in randomized clinical trial.

Mechanisms underlying acquired platinum resistance in high grade serous ovarian cancer - a mini review

BACKGROUND

Advanced epithelial ovarian cancer is one of the hardest human malignancies to treat. Standard treatment involves cytoreductive surgery and platinum-based chemotherapy, however, median progression-free survival for patients diagnosed with advanced stage disease (FIGO stages III and IV) is approximately 18 months. There has been little improvement in overall survival over the past decade and less than half of women with advanced stage disease will be living 5 years after diagnosis. A majority of patients initially have a favourable response to platinum-based chemotherapy, but most will eventually relapse and their disease will become platinum resistant.

SCOPE OF REVIEW

Here, we review our current understanding of mechanisms that promote recurrence and acquired resistance in epithelial ovarian cancer with particular focus on studies that describe differences observed between untreated primary tumors and recurrent tumors, post-first-line chemotherapy. Multiple molecular mechanisms contribute to recurrence in patients following initial treatment for advanced epithelial ovarian cancer including those involving the tumor microenvironment, tumor immune status, cancer stem cells, DNA repair/cell survival pathways and extracellular matrix.

MAJOR CONCLUSIONS

Due to the adaptive nature of recurrent tumors, the major contributing and specific resistance pattern may largely depend on the nature of the primary tumor itself.

GENERAL SIGNIFICANCE

Future work that aims to elucidate the complex pattern of acquired resistance will be useful for predicting chemotherapy response/recurrence following primary diagnosis and to develop novel treatment strategies to improve the survival of patients with advanced epithelial ovarian cancer, especially in tumors not harbouring homologous DNA recombination repair deficiencies.

Platinum or nonplatinum in recurrent ovarian cancer: that is the question

Although platinum-based chemotherapy continues to be the first-line option for advanced ovarian cancer and for platinum recurrences beyond 6 months, platinum rechallenge is not the best approach for some patients, such as those with residual toxicities, platinum-related hypersensitivity reactions or limited platinum-sensitivity (i.e., a platinum treatment-free interval [TFIp] of 6-12 months). Results of the MITO-8 study called into question the role of single-agent nonplatinum-based regimens in this specific subset of ovarian cancer patients. The current article summarizes the results of the MITO-8 study highlighting key limitations, and discusses the role of the nonplatinum-based combination of trabectedin + pegylated liposomal doxorubicin in the management of ovarian cancer patients who relapse between 6 and 12 months after last platinum.

A phase II evaluation of the potent, highly selective PARP inhibitor veliparib in the treatment of persistent or recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer in patients who carry a germline BRCA1 or BRCA2 mutation - An NRG Oncology/Gynecologic Oncology Group study

BACKGROUND

Veliparib is a potent small molecule inhibitor of PARP-1/2, which is cytotoxic in tumor cells with deficiencies in BRCA1 or BRCA2. We studied the clinical activity and toxicity of veliparib in ovarian cancer patients carrying a germline BRCA1 or BRCA2 mutation (gBRCA).

METHODS

Eligibility included three or fewer prior chemotherapy regimens, measurable disease and no prior use of a PARP inhibitor. Veliparib was administered at 400mg orally BID with one cycle being 28days. The two-stage Simon design was capable of detecting a 25% response probability with 90% power while controlling alpha=10% (at a 10% assumed null response probability).

RESULTS

The median age of the 50 eligible patients was 57years (range 37-94) and 14, 18, and 18 patients had 1, 2, and 3 prior therapies respectively. Thirty patients (60%) were platinum-resistant. The median number of cycles administered was 6 (1-27). There was one grade 4 thrombocytopenia. Grade 3 adverse events were: fatigue (n=3), nausea (2), leukopenia (1), neutropenia (1), dehydration (1), and ALT (1). Grade 2 events >10% were: nausea (46%), fatigue (26%), vomiting (18%), and anemia (14%). The proportion responding was 26% (90% CI: 16%-38%, CR: 2, PR: 11); for platinum-resistant and platinum-sensitive patients the proportion responding was 20% and 35%, respectively. The most common reason for treatment discontinuation was progression (62%). Twenty-nine patients are alive; two with SD remain on veliparib. The median PFS is 8.18months.

CONCLUSIONS

The single agent efficacy and tolerability of veliparib for BRCA mutation-associated recurrent ovarian cancer warrants further investigation.

Treatment options in recurrent ovarian cancer: latest evidence and clinical potential

Ovarian cancer (OC) is the fifth most common cause of cancer death in women. Although significant progress has been made in the treatment of OC, the majority of patients experience disease recurrence and receive second-line and sometimes several lines of treatment. Here we review the options available for the treatment of recurrent disease and discuss how different agents are selected, combined and offered in a rationale sequence in the context of multidisciplinary care. We reviewed published work between 1990 and 2013 and meeting abstracts related to the use of chemotherapy and surgery in patients with recurrent ovarian cancer. We discuss treatment regimens, efficacy endpoints and safety profiles of the different therapies. Platinum-based drugs are the most active agents and are selected on the basis of a probability of response to retreatment. Nonplatinum-based chemotherapy regimens are usually given in the 'platinum-resistant' setting and have a modest effect on outcome. Molecular targeted therapy of ovarian cancer given alone or integrated with chemotherapy is showing promising results. Many patients are now receiving more than one line of therapy for recurrent disease, usually platinum based until platinum resistance emerges. The sequential use of chemotherapy regimens and the incorporation of molecularly targeted treatments, either alone or in combination with chemotherapy, have over the last decade significantly extended the median survival of patients with ovarian cancer.

Role of autophagy in cisplatin resistance in ovarian cancer cells

Cisplatin-based treatment is the first line chemotherapy for several cancers including ovarian cancer. The development of cisplatin resistance results in treatment failure, but the underlying mechanisms are not fully understood. Here we show that the induction of autophagy plays an important role in cisplatin resistance in ovarian cancer cells. Specifically, we show that cisplatin resistance is correlated with autophagy induction in a panel of ovarian cancer cells but not in immortalized human ovarian surface epithelial cells. Mechanistically, cisplatin treatment activates ERK and subsequently promotes autophagy. The inhibition of ERK activation with MEK inhibitors or knockdown of ERK expression with siRNA decreases cisplatin-induced autophagy and subsequently sensitizes ovarian cancer cells to cisplatin-induced apoptosis. In ovarian cancer cells that have developed acquired cisplatin resistance, both ERK activation and autophagy induction are increased. Importantly, knockdown of ERK or inhibition of autophagy promotes cisplatin-induced apoptosis in acquired cisplatin-resistant cells. Collectively, our data indicate that ERK-mediated autophagy can lead to cisplatin resistance and suggest that cisplatin resistance can be overcome by inhibition of autophagy in ovarian cancer cells.

Phase II activity of belinostat (PXD-101), carboplatin, and paclitaxel in women with previously treated ovarian cancer

BACKGROUND

Preclinical data show that belinostat (Bel) is synergistic with carboplatin and paclitaxel in ovarian cancer. To further evaluate the clinical activity of belinostat, carboplatin, and paclitaxel (BelCaP), a phase 1b/2 study was performed, with an exploratory phase 2 expansion planned specifically for women with recurrent epithelial ovarian cancer (EOC).

METHODS

Thirty-five women were treated on the phase 2 expansion cohort. BelCap was given as follows: belinostat, 1000 mg/m² daily for 5 days with carboplatin, AUC 5; and paclitaxel, 175 mg/m² given on day 3 of a 21-day cycle. The primary end point was overall response rate (ORR), using a Simon 2 stage design.

RESULTS

The median age was 60 years (range, 39-80 years), and patients had received a median of 3 prior regimens (range, 1-4). Fifty-four percent had received more than two prior platinum-based combinations, sixteen patients (46%) had primary platinum-resistant disease, whereas 19 patients (54%) recurred within 6 months of their most recent platinum treatment. The median number of cycles of BelCaP administered was 6 (range, 1-23). Three patients had a complete response, and 12 had a partial response, for an ORR of 43% (95% confidence interval, 26%-61%). When stratified by primary platinum status, the ORR was 44% among resistant patients and 63% among sensitive patients. The most common drug-related adverse events related to BelCaP were nausea (83%), fatigue (74%), vomiting (63%), alopecia (57%), and diarrhea (37%). With a median follow-up of 4 months (range, 0-23.3 months), 6-month progression-free survival is 48% (95% confidence interval, 31%-66%). Median overall survival was not reached during study follow-up.

CONCLUSIONS

Belinostat, carboplatin, and paclitaxel combined was reasonably well tolerated and demonstrated clinical benefit in heavily-pretreated patients with EOC. The addition of belinostat to this platinum-based regimen represents a novel approach to EOC therapy and warrants further exploration.

Recurrent ovarian cancer: when and how to treat

Notwithstanding continuing efforts to improve the primary treatment for ovarian cancer, most patients will ultimately develop recurrent disease. The benefits of detection and early systemic treatment of recurrence are now in doubt following the presentation of the MRC/EORTC CA125 surveillance trial. The impact of secondary cytoreductive surgery on survival requires more investigation. The role of antiangiogenic and other biological agents such as PARP inhibitors is becoming increasingly important for patients as an addition or alternative to the more conventional cytotoxic therapies available. Uncertainties and choices abound both in the treatment of recurrent ovarian cancer and the timing of such interventions. This article not only explores how to treat these patients but also the controversial issue of when to treat. Educating and involving the patient in decisions about their treatment options is of paramount importance.