Asco 2016 – Embargo snafu tarnishes otherwise promising breast cancer update

Asco’s last-minute rejection last Thursday for embargo-policy violations of Immunomedics’ phase II update on sacituzumab govitecan frustrated what might otherwise have been a positive event at the conference this year in the tough indication of triple-negative breast cancer (TNBC).

Immunomedics had planned to present more mature data for an ongoing 60-patient Phase II study at the conference, but the revelation that the embargoed results had apparently been previously discussed at investor meetings in April left Asco with little choice but to lay down the law. The company had presumably expected the Asco data to be an important confidence builder ahead of the planned – and somewhat delayed – start of a phase III study. In the event Immunomedics’ attempts to build confidence with investors have had exactly the opposite effect.

Nevertheless, the company’s now non-Asco data do still show promise. Immunomedics would have reported a 33% objective response rate, a median progression-free survival of 5.6 months and a median overall survival of 14.3 months in the heavily pretreated group. Patients in the study had to have progressed on at least two prior treatments, including a taxane, and had in fact seen a median of five prior therapies.

Given that third-line or later TNBC typically has an overall survival measured in a few months, the data continue to suggest that sacituzumab govitecan has potential, but the project has been also dogged by visual side-effect issues.

Lowest survival

TNBC accounts for 15% of all breast cancers and has the lowest five-year survival rate of any of the breast cancer subtypes, largely because of the lack of targeted therapies. As a result it has been a focus for pharmaceutical development activities, although few as yet have made it to later-stage trials.

The absence of Immunomedics’ product from Asco this year means that the conference has relatively scant data in the TNBC indication.

What physicians at the conference will see presented later today is an update on Tecentriq, albeit from a small early study, but one that supported the move into phase III with the Impassion130 trial. This study, which tested Tecentriq in combination with Abraxane, showed a confirmed overall response rate of 67% in first-line and 25% and 29% in second and third-line and later patients.  

Another study presented this morning is from a still ongoing phase II trial with Roche’s Cotelliq in combination with paclitaxel in the first-line setting. Roche reported that initial results from the safety run-in had been promising, with eight of 14 patients showing an unconfirmed PR, three with SD and three PD, with two having not completed assessment.

Clinicians active in the space are, however, looking to later-stage studies to define new treatment options. Perhaps most keenly awaited, therefore, is the outcome of the Brightness phase III study of Abbvie’s veliparib as neoadjuvant chemotherapy in early TNBC. Data from this study, one of just a handful of phase IIIs that are currently under way, are due imminently. 

Phase III programmes in triple negative breast cancer 
Project Company Study Pts  Trial ID Data
Veliparib AbbVie Brightness 624 NCT02032277  Imminent
Keytruda Merck & Co Keynote-119 600 NCT02555657 May-17
Sacituzumab govitecan Immunomedics - 328 NCT02574455 Dec-19
Tecentriq Roche Impassion130 900 NCT02425891 Apr-20
Tecentriq Roche NeoTRIPaPDL1 - NCT02620280 Jan-22
Xtandi Medivation ENDEAR 780 - -

EP Vantage will continue to report live from Asco. To contact the writer of this story email Robin Davison at news@epvantage.com or follow @RobinDavison2 on Twitter

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