What happened

Shares of Cardiff Oncology (CRDF -1.18%) were trading 19.8% lower as of 11:44 a.m. EST on Friday. The big drop came after the company presented data from a phase 1b/2 study of onvansertib in treating KRAS-mutated metastatic colorectal cancer (mCRC) at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium.

So what

Biotech stocks don't plunge when investors are happy with clinical trial updates. It's obvious that at least some investors were disappointed by Cardiff's latest news.

Man wearing coat and tie holding a red line with an arrow pointing downward

Image source: Getty Images.

Only 12 patients in the phase 1b/2 study were evaluable in time to be included in the ASCO presentation. Five of them achieved a partial response (some tumor shrinkage) with four patients having confirmed partial responses. Eight demonstrated what Cardiff described as "durable responses" of at least six months.

In addition, the company stated that onvansertib in combination with chemotherapy was found to be safe and well-tolerated. Cardiff said that 9% of adverse events reported in the study were grade 3 (severe) or grade 4 (life-threatening).

While some investors seem to have been hoping for better results, Cardiff and the team involved with the study were upbeat. Lead investigator Daniel Ahn of the Mayo Clinic Cancer Center in Arizona said that the data "highlights the promise of onvansertib plus standard-of-care as an effective second-line treatment for patients with KRAS-mutated mCRC." Cardiff Oncology CEO Mark Erlander stated that the company is "pleased with the continued advancement of our KRAS-mutated mCRC clinical study."

Now what

Cardiff is now moving forward with the phase 2 part of its study of onvansertib, which is expected to enroll 26 patients across six trial sites.