Cascadian’s Phase II tucatinib study in HER2+ CRC needs to reach 30-40% ORR, mechanism/target divides experts on hitting endpoint mark

21 Sep 2017

Cascadian’s Phase II tucatinib study in HER2+ CRC needs to reach 30-40% ORR, mechanism/target divides experts on hitting endpoint mark

Cascadian Therapeutics’ (NASDAQ:CASC) ONT-380 (tucatinib) for HER2+ colorectal cancer (CRC) needs to reach 30-40% in its Phase II primary endpoint of objective response rate (ORR) to be considered a clinical success, experts said. They said this could be achievable given preclinical data presented at the ESMO Congress in Madrid shows tucatinib as active in HER2+ tumour models.

However, the same experts said persistent questions remain if HER2 is a valid target for CRC, drawing some Phase II success reservations.

An analyst report rates the drug as highly important to the company and states a positive result in this Phase II MOUNTAINEER trial could help increase Cascadian revenue, without commenting on trial, market success prospects or sales forecasts.

An ongoing Phase II trial investigating Novartis’ (VTX:NOVN) Tykerb (lapatinib) and Roche’s (VTX:ROG) Herceptin (trastuzumab) in HER2+ CRC (NCT03225937), which yielded positive results, also draws optimism for tucantinib’s mechanism, others said. Tucantinib’s specific HER2 target is also reassuring as it could lead to a cleaner safety profile, some added.

Some trial reservations linger in that since tucatinib only targets HER2 whilst Tykerb also targets the EGFR gene, so the Tykerb trial may be an inappropriate guarantee of HER2 target, some added. There is also limited overall data investigating HER2 in CRC if compared in breast cancer, and such data blanks may need to be clarified, some added.

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