Arcellx Shares Plunge 16.89% on Surging Volume as Kelonia's Early CAR-T Data Sparks Market Jitters and 427th U.S. Equity Ranking

Market Snapshot

, 2025, despite a surge in trading activity. , , . equities. The sharp decline followed the release of early-stage clinical data from privately held Kelonia Therapeutics, a competitor in the multiple myeloma (MM) CAR-T therapy space. While Arcellx’s anito-cel candidate is in phase 3 trials, Kelonia’s KLN-1010—a novel in-vivo CAR-T approach—showed preliminary efficacy in a small trial, sparking market concerns about competitive positioning.

Key Drivers

The stock’s decline reflects investor reaction to Kelonia Therapeutics’ phase 1 results for KLN-1010, an experimental CAR-T therapy for relapsed or refractory MM. , with persistence of CAR-T cell activity observed without requiring , apheresis, or ex vivo cell manufacturing. These results, though preliminary, highlight KLN-1010’s potential to streamline the complex and costly , a key differentiator in a competitive market. However, the trial’s limitations—including a small sample size, , and absence of long-term safety data—were emphasized by analysts as overblown concerns by some market observers.

Arcellx’s anito-cel, its autologous anti– in phase 3 trials, remains a direct competitor to KLN-1010. Anito-cel’s development involves ex vivo cell modification, a process that Kelonia’s in-vivo approach aims to bypass. Analysts such as Guggenheim’s and Citi’s argued that the market’s negative reaction to Kelonia’s data was disproportionate, given anito-cel’s more advanced clinical stage and established partnerships, including its collaboration with Gilead Sciences’ Kite Therapeutics. Both analysts maintained “buy” ratings on Arcellx, citing the lack of robust evidence that KLN-1010’s in-vivo strategy will disrupt the existing CAR-T landscape.

The competitive dynamics in the MM therapy market were further underscored by Kelonia’s recent collaboration agreement with Johnson & Johnson (JNJ), a major player in the field with its approved CAR-T therapy, Carvykti. This partnership raises questions about potential cross-licensing or co-development opportunities that could influence the commercial trajectory of both KLN-1010 and J&J’s existing products. However, Arcellx’s anito-cel, if approved, would directly compete with J&J’s Carvykti and Bristol Myers Squibb’s Abecma, both of which are already commercialized. The upcoming presentation of KLN-1010 and anito-cel data at the American Society of Hematology 2025 Annual Meeting in December will likely provide further clarity on their respective clinical profiles.

Investor sentiment was also shaped by broader market skepticism toward early-stage biotech data, particularly in a sector where long-term safety and efficacy are critical. Kelonia’s results, while promising, lack the robustness of larger, longer-term trials. Additionally, . Analysts reiterated that anito-cel’s phase 3 status and established partnerships provide a significant edge over early-stage in-vivo alternatives, even if the latter’s logistical advantages are theoretically compelling.

, according to market observers. While Kelonia’s approach could eventually reshape CAR-T delivery models, its current data lacks the maturity to justify a revaluation of Arcellx’s pipeline. Analysts highlighted that anito-cel’s ex vivo process, though more resource-intensive, has demonstrated consistent clinical progress and regulatory momentum. Until Kelonia provides larger, longer-term data, .