Companies race to pair up chemotherapy drugs with immune system-boosting antibodies to greatest effect in trials

A joint clinical trial agreement between Merck & Co and Pfizer is the latest in what is becoming a rather tangled web of tie-ups between companies with cancer drugs that harness patients’ immune systems. These immuno-oncology drugs stop tumours from disguising themselves from natural defence mechanisms, but work better when more than one of these pathways are blocked simultaneously, or in combination with chemotherapy agents that will attack tumours directly. Hence, companies are touting their products as widely as possible to counterparts with complementary drugs.

This agreement will see Merck & Co’s anti-programmed death-ligand 1 (PD-L1) antibody, pembrolizumab, tested with Pfizer’s lung cancer drug Xalkori (crizotinib) in a Phase 1b trial. Trials of pembrolizumab and a second Pfizer drug at a much earlier developmental stage have also been agreed.

Merck & Co has already signed up several other partners to test combinations of their drugs with pembrolizumab. In February, the company revealed plans involving yet another Pfizer drug – Inlyta (axitinib) for renal cell carcinoma – as well as Amgen’s cancer-killing virus talimogene laherparepvec, and Incyte’s indoleamine dioxygenase-1 (IDO1) inhibitor, INCB24360.

Incyte itself has struck deals to run trials of INCB24360 with Roche subsidiary Genentech’s anti-PD-L1 antibody MPDL3280A; two antibody treatments from Bristol-Myers Squibb (BMS) (nivolumab and ipilimumab); and MEDI4736, an anti-PD-L1 antibody from AstraZeneca’s biological drugs subsidiary MedImmune.

In turn, several of those drugs are involved in combination trials elsewhere: BMS and Celgene are investigating nivolumab in combination with Abraxane – a version of blockbuster cancer drug Taxol (paclitaxel) bound to the blood protein albumin; and MedImmune has signed up with antibody drugmakers Advaxis in the US and Kyowa Hakko Kirin of South Korea.