Bellicum's GoCAR-Ts crash out of clinic over safety signal, sparking search for strategic alternatives

Bellicum Pharmaceuticals’ GoCAR-T cell therapies have skidded out, with the biotech halting trials of the two candidates over dose-limiting toxicities. The evaporation of Bellicum’s pipeline prompted the CAR-T cell therapy specialist to start an evaluation of strategic alternatives.

Houston-based Bellicum was running phase 1/2 clinical trials of two CAR-T candidates, namely the PSCA prospect BPX-601 and the HER2 candidate BPX-603. Both assets use the biotech’s GoCAR-T technology. BPX-601 expresses a rimiducid-inducible co-activation switch to enhance T cell potency and persistence. And BPX-603 features both the co-activation switch and a CaspaCIDe safety switch.

Bellicum pitched the switches as ways to boost effector cell proliferation, enhance functional persistence  and empower physicians to wipe out the CAR-T cells in the event of a serious side effect such as cytokine release syndrome. Yet, the early data on the candidates have discouraged Bellicum.

The most recent metastatic castration-resistant prostate cancer patient to receive BPX-601 experienced serious immune-mediated adverse events including grade 4 cytokine release syndrome. The adverse events marked the second time Bellicum has seen a dose-limiting toxicity in that dose escalation cohort.

In response, the biotech paused enrollment and reviewed the data. The review showed four of the nine prostate cancer patients experienced a 90% or greater reduction in the PSA biomarker. But also revealed the need to optimize either the clinical dose and schedule of BPX-601 and the activating agent rimiducid, or the design of the BPX-601 cell construct to make the benefits outweigh the risks. 

Bellicum, which ended September with $28.8 million to its name, lacks the cash to pull off the BPX-601 rescue mission, leading it to stop clinical trials of the candidate and its other pipeline prospect BPX-603. With all clinical development winding down, the biotech is now evaluating strategic alternatives.  

The initiation of the evaluation suggests Bellicum’s drawn-out demise is now nearing the end. Back in 2014, the biotech was one of three CAR-T cell therapy developers to arrive on Nasdaq. The other two cell therapy developers—Kite Pharma and Juno Therapeutics—went on to land multi-billion dollar buyouts and deliver commercial products. 

Bellicum has looked unlikely to follow in the footsteps of the other members of the CAR-T class of 2014 for several years. In 2020, the company laid off 79% of its employees after BPX-601 delivered lackluster safety and efficacy data.