The ASCO Post recently reported findings of high response rates and improved survival from the combination of platinum-based cisplatin and gemcitabine (chemotherapy) in BRCA/PALB2 mutation positive pancreatic ductal adenocarcinoma.
The goal of the Phase 2 study was to investigate cisplatin and gemcitabine alone or in combination with veliparib, a PARP inhibitor.
The Post published the findings in its review of a presentation by Dr. Eileen O’Reilly of Memorial Sloan Kettering Cancer Center. Dr. O’Reilly’s presentation was given at a recent gastrointestinal cancer symposium.
The findings have also been reported in the Journal of Clinical Oncology.
About Pancreatic Ductal Adenocarcinoma (PDAC)
PDAC is an aggressive and rare disease but still the most common cancerous malignancy of the pancreas. It is difficult to treat. Surgical removal currently provides a chance to destroy the tumor.
Yet about eighty to ninety percent of patients with the disease are already incurable by the time they are seen at a clinic.
About Cisplatin, Gemcitabine, and Veliparib
Cisplatin, a platinum-based chemotherapy, is generally prescribed in the treatment of cancer. However, although it is effective, it is known to cause severe side effects such as DNA damage. These adverse events may cause limiting or even cessation of treatment.
Gemcitabine is an antimetabolite that is very much like normal substances in a cell. Cells are no longer able to divide when these substances are incorporated into cellular metabolism. Antimetabolites attack cells when they are dividing (cell-specific).
Veliparib blocks the PARP protein. The drug prevents the repair of genetic damage in cancer cells making them more susceptible to cancer treatments.
Exceeding Expectations
Dr. O’Reilly said that the investigators noted a two-year survival (31%) and a three-year survival (18%) which is the longest survival period in a trial for advanced pancreatic ductal adenocarcinoma.
The response rate for the cisplatin and gemcitabine combination was 65.2 percent while adding veliparib produced a response rate of 74.1 percent.
The Phase 1 and 2 Trials
Dr. O’Reilly previously led a Phase 1 trial that showed results of a 78 percent response rate with the drugs cisplatin and gemcitabine plus veliparib. The median survival was 23 months. Fifty patients were included in the trial.
The current Phase 2 trial involved:
- Arm A – cisplatin and gemcitabine on days three and ten with veliparib taken orally every three weeks two times each day on days one to 12.
Note that these patients were also given the option of oral veliparib as a maintenance treatment.
- Arm B consisted of receiving cisplatin and gemcitabine without the addition of veliparib.
The dosage for Arm A is:
- Cisplatin 25mg/m2
- Gemcitabine 600mg/m2 on days three and ten
- Veliparib 80mg orally two times each day from days one to 12 every three weeks; these patients are given an option of veliparib for maintenance
The dosage for Arm B is identical to that of Arm A but without treatment with veliparib.
The trial had as its primary endpoint the response rates (RR) of both arm A and arm B which were analyzed separately.
Toxicity Profile
Hematologic toxicity, which is a decrease in bone marrow or blood cells, occurred in ninety percent of patients in arm A and seventeen percent of patients in arm B.
Trial Endpoints
The excellent report led the investigators to suggest that cisplatin/gemcitabine should be considered as standard-of-care for BRCA-mutated advanced pancreatic ductal adenocarcinoma.
Exceeding Expectations
Dr. O’Reilly said that the investigators of the Phase 2 trial recorded the longest survival period in a trial for advanced pancreatic ductal adenocarcinoma.
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