Scientist at work in a laboratory

Data from the Phase IB dose expansion study of BGB-283 (BeiGene), a novel RAF inhibitor with unique RAF dimer and EGFR inhibition activities, in patients with B-RAF or K-RAS/N-RAS mutated solid tumors was presented in an oral presentation during a Clinical Trials Plenary Session at the 2017 American Association for Cancer Research (AACR) Annual Meeting in Washington, DC, confirms? anti-tumor activity in both B-RAF and K-RAS-mutated tumors .

BGB-283 is a novel inhibitor of RAF, in both its monomeric and dimeric forms, and has demonstrated activity in both B-RAF and K-RAS-mutated tumors in preclinical studies and in the Phase IA dose escalation portion of this Phase I study. In the Phase IB portion, BGB-283 has generally been well-tolerated at a dose of 30 mg once a day (QD) and has continued to show antitumor activity not only in subjects with B-RAF V600-mutated solid tumors, but also in subjects with K-RAS-mutated solid tumors.

Desirable Risk-benefit
?BGB-283 appears to have a desirable risk-benefit profile in the combined efficacy and safety data from the Phase IA and IB parts of this study. Clinical activity has been observed for BGB-283 not only in B-RAF V600-mutated melanoma, thyroid cancer, and ovarian cancer, but also in K-RAS-mutated non-small cell lung cancer and endometrial carcinoma,” noted the coordinating principal investigator of the study, Jayesh Desai, MD, FRACP, a medical oncologist at The Royal Melbourne Hospital and the Peter MacCallum Cancer Centre in Melbourne, Australia.

“These observations warrant further investigation of BGB-283 in the clinic,” Desai added.

?Data from the Phase IB trial of BGB-283 further supported the anti-tumor activity in both RAF- and RAS-mutated tumors that we observed in the Phase IA study. We look forward to continuing clinical development of BGB-283 as either a single agent or in combination with other targeted or immuno-oncology agents,? said Amy Peterson, MD, Chief Medical Officer, Immuno-oncology at BeiGene.

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Trial Results
The multicenter, open-label Phase I trial of BGB-283 conducted in Australia and New Zealand is comprised of two parts ? Phase IA (dose-escalation) and Phase IB (dose-expansion) in patients with B-RAF or K-RAS/N-RAS mutated solid tumors or patients with pancreatic cancer. The dose-expansion portion of the trial was designed to evaluate the safety and efficacy of BGB-283 at the recommended Phase II dose of 30 mg QD established in the Phase IA part of the trial.

The expansion cohorts include patients with B-RAF V600-mutated cancers including melanoma, either na?ve or having developed resistance to existing B-RAF or MEK inhibitors, colorectal cancer (CRC), non-small cell lung cancer (NSCLC), and papillary thyroid cancer (PTC), as well as patients with other B-RAF-mutated solid tumors. They also include patients with K-RAS/N-RAS-mutated endometrial cancer, NSCLC, and CRC, as well as patients with other K-RAS/N-RAS-mutated solid tumors and patients with pancreatic cancer.

The safety analysis, which included 96 patients as of the September 12, 2016 cut-off, suggested that BGB-283 was generally well-tolerated at 30 mg QD, with most drug-related adverse events (AEs) being grades 1 or 2 in severity. The most frequent drug-related AEs (?10%) of any grade were fatigue (38.5%), dysphonia (26.0%), decreased appetite (21.9%), palmar-plantar erythrodysaesthesia syndrome (21.9%), thrombocytopenia (19.8%), dermatitis acneiform (17.7%), diarrhea (16.7%), rash (16.7%), nausea (15.6%), hypertension (11.5%), and glossodynia (10.4%).

The most frequent drug-related grade 3-4 AEs (?2%, 2 patients or more) included fatigue (7.3%), hypertension (6.3%), thrombocytopenia (6.3%), pyrexia (3.1%), hyponatremia (2.1%), anemia (2.1%), neutropenia (2.1%), febrile neutropenia (2.1%), decreased platelet count (2.1%), increased alanine aminotransferase (2.1%), increased gamma-glutamyltransferase (2.1%), and sepsis (2.1%).

The cut-off for the efficacy analysis was September 17, 2016. In seven patients with B-RAF V600-mutated melanoma (including one V600K and one V600R) who were na?ve to B-RAF or MEK inhibitors, there were three partial responses (PRs) and three cases of stable disease (SD). In three patients with B-RAF V600-mutated PTC, there was one PR and two cases of SD. In six patients with K-RAS-mutated NSCLC, there was one PR and two cases of SD. In ten patients with solid tumors with B-RAF non-V600 mutations or solid tumors with B-RAF V600 mutations that are not included in other cohorts, there were two PRs, in one patient with BRAF V600E-mutated melanoma and one with BRAF V600E-mutated ovarian cancer, and three cases of SD. In two patients with B-RAF V600-mutated NSCLC, there was one unconfirmed PR and one case of SD.

Additional cases of stable disease were observed in four of six melanoma patients with B-RAF V600-mutated melanoma who had responses to but developed resistance against B-RAF or MEK inhibitors, nine of 13 patients with B-RAF V600-mutated CRC, five of five patients with K-RAS-mutated endometrial cancer, 12 of 20 patients with K-RAS/N-RAS-mutated CRC, and 10 of 21 patients with other K-RAS/N-RAS-mutated solid tumors or pancreatic cancer.

In the Phase IA portion of the study, confirmed objective responses included a complete response in a patient with B-RAF V600E-mutated melanoma, and two PRs, one in a patient with B-RAF V600E-mutated thyroid cancer and one in a patient with K-RAS-mutated endometrial cancer.

Last editorial review: April 2, 2017.

Featured Image: Blood Test. Courtesy: 2016 Fotolia. Used with permission. Photo 1.0: Rachel Karchin, PhD. Courtesy: 2016 Will Kirk/Homewood Photography. Used with permission

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