Veliparib for the treatment of solid malignancies

OBJECTIVE

Veliparib is a poly adenosine diphosphate ribose polymerase (PARP) -1 and -2 inhibitor with chemo-sensitizing and anticancer activities that has shown promising results in early-phase trials. The aim of this comprehensive review is to summarise the profile of veliparib and to provide an overview of its early clinical investigations.

DATA SOURCES

Details of all the completed trials evaluating the profile of veliparib were identified from ClinicalTrials.gov with the relevant keywords. Furthermore, databases such as Google Scholar and PubMed were searched using the National Clinical Trial (NCT) number to retrieve publications of results not listed in the trial registry.

DATA SUMMARY

A total of 25 completed clinical trials indicating the use of veliparib in solid malignancies were identified. The results showed that veliparib is well tolerated, both as a single agent and in combination with standard chemotherapy doses. Being a broad-spectrum potentiator of DNA-damaging agents and radiation, it has shown to improve the clinical outcomes, particularly in solid tumors like ovarian cancer, breast cancer and lung cancer.

CONCLUSIONS

The results from clinical trials indicate that veliparib can be an excellent therapeutic strategy for BRCA mutation associated cancers and tumors bearing deficiencies in the HR pathway as well. Further studies establishing the dosing, sequence of therapy, extended use and compatibility with various anti-cancer drugs are warranted to define its exact role in cancer therapy.

An Overview of PARP Inhibitors for the Treatment of Breast Cancer

Loss-of-function mutations in BRCA1 and BRCA2 are detected in at least 5% of unselected patients with breast cancer (BC). These BC susceptibility genes encode proteins critical for DNA homologous recombination repair (HRR). This review provides an update on oral poly(ADP-ribose) polymerase (PARP) inhibitors for the treatment of BC. Olaparib and talazoparib are PARP inhibitors approved as monotherapies for deleterious/suspected deleterious germline BRCA-mutated, HER2-negative BC. Olaparib is approved in the USA for metastatic BC and in Europe for locally advanced/metastatic BC. Talazoparib is approved for locally advanced/metastatic BC in the USA and Europe. In phase 3 trials, olaparib and talazoparib monotherapies demonstrated significant progression-free survival benefits compared with chemotherapy. Common toxicities were effectively managed by supportive treatment and dose interruptions/reductions. Veliparib combined with platinum-based chemotherapy has also shown promise for locally advanced/metastatic BC in a phase 3 trial. Differences in efficacy and safety across PARP inhibitors (olaparib, talazoparib, veliparib, niraparib, rucaparib) may relate to differences in potency of PARP trapping on DNA and cytotoxic specificity. PARP inhibitors are being investigated in early BC, in novel combinations, and in patients without germline BRCA mutations, including those with somatic BRCA mutations and other HRR gene mutations. Ongoing phase 2/3 studies include PARP inhibitors combined with immune checkpoint inhibitors for the treatment of triple-negative BC. Wider access to testing for BRCA and other mutations, and to genetic counseling, are required to identify patients who could benefit from PARP inhibitor therapy. The advent of PARP inhibitors has potential benefits for BC treatment beyond the locally advanced/metastatic setting.

A phase 1 dose-escalation study of veliparib with bimonthly FOLFIRI in patients with advanced solid tumours

Background

Veliparib is a potent poly(ADP-ribose) polymerase inhibitor. This phase 1 study aimed to establish the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of veliparib combined with various FOLFIRI regimens in patients with solid tumours.

Methods

Patients received veliparib (10–270 mg BID, days 1–5, 15–19) and FOLFIRI (days 1–3, 15–17) in three regimens containing 5-fluorouracil 2,400 mg/m²: irinotecan 150 mg/m² and folinic acid 400 mg/m² (part 1); irinotecan 180 mg/m², folinic acid 400 mg/m², and 5-fluorouracil 400 mg/m² bolus (part 2), or irinotecan 180 mg/m² (part 3). The RP2D was further evaluated in safety expansion cohorts. Preliminary antitumour activity was also assessed.

Results

Ninety-two patients received ≥1 veliparib dose. MTD was not reached; RP2D was set at 200 mg BID veliparib plus FOLFIRI (without 5-fluorouracil bolus). Most common treatment-emergent adverse events were neutropenia (66.3%), diarrhoea, and nausea (60.9% each). Dose-limiting toxicities (n = 4) were grade 3 gastritis and grade 4 neutropenia and febrile neutropenia. Veliparib exposure was dose-proportional, with no effects on the pharmacokinetics of FOLFIRI components. Fifteen patients had a partial response (objective response rate, 17.6%).

Conclusions

The acceptable safety profile and preliminary antitumour activity of veliparib plus FOLFIRI support further evaluation of this combination.

Phase 1 dose-escalation study of single-agent veliparib in Japanese patients with advanced solid tumors

Veliparib (ABT‐888) is a potent, orally bioavailable poly(ADP‐ribose) polymerase‐1 and ‐2 inhibitor. This phase 1 study evaluated the tolerability, pharmacokinetic profile, safety, and preliminary antitumor activity of single‐agent veliparib in Japanese patients with advanced solid tumors. Eligible patients were assigned to treatment with veliparib at 200 or 400 mg dose; veliparib was self‐administered orally twice daily on days 1–28 of 28‐day cycles. Dose escalation, following a 3 + 3 design, defined dose‐limiting toxicities, the maximum tolerated dose, and the recommended phase 2 dose. Sixteen patients were enrolled (median age, 59 years). Fourteen patients had high‐grade serous ovarian cancer, one had primary peritoneal cancer, and one had BRCA‐mutated breast cancer. The most frequent treatment‐emergent adverse events were nausea and vomiting (93.8% each), decreased appetite (62.5%), abdominal pain, diarrhea, and malaise (31.3% each). A grade ≥3 toxicity was observed in 50% of patients; one patient each in the 200 mg (n = 4) and 400 mg (n = 12) cohorts experienced serious adverse events. Dose‐limiting toxicities were observed for one patient at the 400 mg dose. No toxicities leading to death were reported. The recommended phase 2 dose was defined as 400 mg twice daily. The veliparib pharmacokinetic profile was consistent with that reported for the Western population. Two patients, both with ovarian cancer, had a RECIST partial response. Veliparib monotherapy showed manageable tolerability and safety profiles and a predictable pharmacokinetic profile at a 400 mg twice‐daily dose, and supports the inclusion of Japanese patients in the multinational phase 3 study (NCT02470585).