Cobimetinib plus gemcitabine is an active combination in KRAS G12R-mutated in previously chemotherapy-treated and failed pancreatic patients

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Background: he KRAS proto-oncogene is involved in the RAS/MAPK pathway. Various G12X mutations have been examined with the most common mutations being G12D (40%), G12V (30%), and G12R (15-20%) in pancreatic cancer patients. Throughout the course of studying the G12X mutations, we have observed that not all KRAS mutations are equal. Preclinical data shows G12R is impaired in pI3Kα signaling, as compared to KRAS G12V/D. This mechanism is important in PDAC as it allows tumor growth to be sustained. In preclinical studies, PDX derived tumors were transplanted in mice and were treated with a MEK inhibitor plus chemotherapy, which demonstrated a greater tumor regression than either agent alone. Therefore, we have decided to treat patients with Gemcitabine alongside a 2nd generation MEK inhibitor (Cobimetinib). Methods: In our single arm study, 13 KRAS mutated pancreatic patients (KRAS G12D, G12V, and G12R) received the combination of Cobimetinib 20mg BID weekly for three weeks alongside Gemcitabine at 1000mg/m2 weekly, followed by one week of rest. The above constitutes one cycle. Results: Patients were divided into two groups; Group 1 consists of seven patients that were KRAS G12D/G12V mutated, and Group 2 included six KRAS G12R mutated patients. In Group 1, seven patients on treatment progressed and died within two months on the study. In Group 2, one achieved PR and others stable disease. Median progression-free survival was 6.0 months (95% CI 3-9.3 months) and median OS has not been reached. All patients are alive at 8 months. Common adverse reactions include rash, fatigue, nausea, and vomiting. Cancer antigen 19-9 decreased in ≥ 50 of all patients in the latter group. We would like to report our positive study to the society. Moreover, we intend to confirm the study in a larger patient cohort. Conclusions: Pancreatic cancer patients that demonstrate KRAS G12R mutations are treatable with a new active combination chemotherapy.

Neoadjuvant and adjuvant, floxuridine, leucovorin, oxaliplatin, and docetaxel (FLOD) in patients with locally advanced operable gastroesophageal adenocarcinoma: A phase II study with pathologic responses and long term follow-up

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Background: A complete pathological response to neoadjuvant chemotherapy without the use of radiation has infrequently been reported in operable chemo-naïve stage III gastro esophageal adenocarcinoma patients. Methods: Twenty-nine patients were enrolled in this study. Neoadjuvant therapy consisted of Floxuridine, Leucovorin, Oxaliplatin, and Docetaxel and was administered in 2, four week cycles. Chemotherapy consisted on day one and day fifteen; Oxaliplatin, Docetaxel, FUDR, and Leucovorin. The latter two drugs were given concurrently over twenty four hours. On day eight, chemotherapy consisted of Docetaxel, FUDR, and Leucovorin. Following therapy, patients underwent surgical resection. Those patients having residual disease were offered adjuvant chemotherapy. Patients having a complete pathological response were not offered any further therapy. Results: Twenty-four out of twenty-nine patients completed neoadjuvant therapy and underwent esophagectomy. Two were declared inoperable after treatment. Three patients died prior to surgery. The median follow-up of all patients is now sixty months. The median overall survival has not been reached at sixty months. Five yr actual OS is 51%. Clinical response to neoadjuvant therapy was seen in (72.4%) patients. Complete pathological response to neoadjuvant therapy was seen in (16.7%) who are disease free at sixty month follow-ups. Seven out of twenty-four patients achieved partial pathological response (29.1%) and received adjuvant chemotherapy. They are all alive (100%). Eight patients achieved less than partial pathological response and received adjuvant chemotherapy, four out of eight are alive at sixty months (50%). Grade three and four toxicities were seen in sixteen out of twenty nine patients during neoadjuvant therapy. Grade three and four toxicities were seen in six out of fourteen patients during adjuvant therapy. Conclusions: Our chemotherapy regimen of Floxuridine, Leucovorin, Oxaliplatin and Docetaxel (FLOD) has resulted in long term survival in patients with adenocarcinoma of the esophagus. Clinical trial information: NCT00448760.