Around this time last year, investors were thrilled with bluebird bio (BLUE 1.78%), and a next-generation cancer therapy that the pre-commercial biotech is developing in partnership with Celgene (CELG). The partners recently presented encouraging clinical trial results, but they're not the only ones trying to help a limited population of advanced-stage multiple myeloma patients.

Results from a similar program with backing from Johnson & Johnson (JNJ 0.29%) could present some tough competition going forward, and Amgen (AMGN 0.60%) recently reported encouraging results from a much simpler solution aimed at the same limited patient group. But before you panic and jump ship, let's look at what threatens Bluebird's blood cancer candidate.

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Hooray for BCMA

Celgene and Bluebird lifted a lot of spirits with results from 12 multiple myeloma patients treated with bb21217. This is a cellular cancer therapy that involves removing multiple myeloma patients' immune cells, then having them modified off site to recognize B-cell maturation antigen (BCMA), a surface protein often found on tumor cells. Mixing up a new batch for each patient isn't easy, but it looks like it's worth the effort.

Multiple myeloma gets harder to treat following each relapse, so eliciting any response from a group of patients who had already relapsed at least four times -- the median was seven -- would have been an accomplishment. Investors were thrilled to see 10 out of 12 patients treated with bb21217 achieve an objective response at an interim update.

Four of the 10 patients that showed a response had been dosed less than four months earlier, so it's going to be a long time before we know how valuable bb21217 could be for Bluebird and Celgene. While we're waiting, a couple of potential rivals are aiming for the same target with impressive results.

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The threat from a big legend that teamed up with a small one

Johnson & Johnson is a pharmaceutical legend on pace to generate $10 billion in sales from oncology drugs this year. That's why Legend Biotech, a pre-commercial-stage biotech, was eager to team up with J&J late last year to develop LCAR-B38M, a cellular therapy that targets two regions of BCMA.

Results from an ongoing study with 57 patients spread across four locations in China suggest bb21217 will have some tough competition. A whopping 74% of the patients that received LCAR-B38M achieved complete remission. That doesn't bode well for Bluebird's candidate, which elicited complete responses from just three of 12 patients treated.

Although it looks like Legend's candidate wiped the floor with bb21217, there was a lot of variation between the multiple myeloma patients involved in the two studies. Legend enrolled some patients who had only seen one other treatment, and the median number of previous relapses was just three. Results from LCAR-B38M are impressive, but it's way too early to confidently say it will outperform Bluebird's candidate.

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A better mousetrap?

Amgen received a great deal of attention for an experimental multiple myeloma treatment -- AMG-420 -- that oncologists can plug into an IV line as soon as their patients agree to it. Amgen's bi-specific T-cell engager, or BiTE, isn't a cellular therapy. Instead, it's a relatively simple protein that does something pretty amazing. One end of AMG-420 binds to BCMA on cancer cells while the opposite end engages T-cells as they float past.

Hailing T-cells like taxis appears to work, although their role in the future treatment paradigm is still far from certain. Investigators infused 42 patients with a wide range of dosage strengths, and it looks like they found one that's effective and tolerable. AMG-420 elicited responses from 13 patients, seven of whom were in a group of 10 that received the dosage strength that Amgen will probably advance into larger studies.

If approved, patients won't have to wait for weeks and undergo immune-system-depleting regimens before receiving AMG-420, but there's still a catch. Amgen's candidate needs to be infused for four continuous weeks out of every six-week cycle.

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Looking ahead

Another one of Celgene's partners recently impressed investors with luspatercept, a red blood cell booster with blockbuster potential. Celgene's stock price stumbled this year, but it's still a highly profitable company with a lot of irons in the fire. 

Although bb21217 gets more attention than the rest of Bluebird's pipeline, it isn't the biotech's most advanced candidate. European regulators are already reviewing Bluebird's application for LentiGlobin, an experimental gene therapy intended to treat inherited blood disorders, and a U.S. filing should be ready early next year.

Shares of Bluebird have fallen 35% in 2018, but it's still a $6.3 billion company that doesn't have any products to sell yet. The stock could probably survive a successful attack on bb21217, but investors would suffer some significant losses.