Celldex Therapeutics discontinued the investigator-led Phase Ib trial investigating CDX-3379 in combination with Novartis’ MEK-inhibitor Mekinist (trametinib) in melanoma due to significant gastrointestinal (GI) side effects, a source familiar with the trial said. 

The study had enrolled three out of its 10-patient target when it was stopped, the source added.

The open-label Phase Ib/II trial (NCT03580382), which is still listed as recruiting on ClinicalTrials.gov, is focused on advanced-stage NRAS-mutant and BRAF/NRAS wild-type melanoma patients.

When asked to comment on this article, a Celldex spokesperson noted that since the trial is an investigator-sponsored initiative, the company is not at liberty to comment. Celldex is sponsoring CDX-3379’s evaluation in a 45-patient, open-label, Phase II head and neck squamous cell carcinoma (HNSCC) trial (NCT03254927) in combination with Eli Lilly’s epidermal growth factor receptor (EGFR) inhibitor Erbitux (cetixumab). The source declined to comment on whether the side effects seen in the melanoma trial might also be an issue in the HNSCC trial.

The melanoma trial page was last updated on 24 January, and the first patient was enrolled on 6 July 2018, according to ClinicalTrials.gov. The Phase Ib portion of the study was meant to determine the dose for Phase II, which would then assess response rates and duration of response.

CDX-3379 is a monoclonal antibody targeting ERBB3, a receptor theorised to have a pivotal role in regulating cancer cell growth and survival, as well as resistance to targeted therapies. Mekinist was approved in May 2013 and is labelled both as a monotherapy and in combination with Novartis’ Tafinlar (dabrafenib) for unresectable or metastatic melanoma with BRAF V600E or V600K mutations. Most common adverse reactions (≥20%) for Mekinist as a single agent include rash, diarrhoea and lymphedema, according to its label.

Celldex has a market cap of $32.74m. The company has had a series of failed therapies, starting in 2016 when its shares went down 54.8% after a preplanned interim analysis revealed that its Phase III ACT IV trial assessing rindopepimut in newly diagnosed EGFRvIII-positive glioblastoma would not reach statistical significance in the primary endpoint of overall survival due to the control arm outperforming. In 2018, Celldex shares dropped 64.9% after its Phase IIb METRIC trial looking into glembatumumab vedotin failed to show benefit versus the comparator in triple-negative breast cancer.

by Reynald Castaneda in London

Reynald Castaneda is a Senior Reporter for Clinical Trials Arena parent company GlobalData’s investigative journalism team. A version of this article originally appeared on the Insights module of GlobalData’s Pharmaceutical Intelligence Center. To access more articles like this, visit GlobalData.