Cellectar Biosciences Announces CLR 131 Achieves Primary Efficacy Endpoints from Its Phase 2 CLOVER-1 Study in relapsed/refractory B-cell Lymphomas and Completion of the Phase 1 relapsed/refractory Multiple Myeloma Dose

Cellectar Biosciences

Announces CLR 131 Achieves Primary Efficacy Endpoints from Its Phase 2 CLOVER-1 Study in relapsed/refractory B-cell Lymphomas and

Completion of the Phase 1 relapsed/refractory Multiple Myeloma Dose Escalation Study

42.8% ORR in multiple myeloma at the

75mCi total body dose

42.0% ORR and 11% CRR in all non-Hodgkin's

lymphoma (NHL) patients

100% ORR seen in Lymphoplasmacytic

Lymphoma/Waldenstrom's Macroglobulinemia (LPL/WM) patients

76.7% of the multiple myeloma patients

across all doses tested experienced tumor reduction with a strong dose response

FLORHAM PARK, N.J., February 19, 2020 --

Cellectar Biosciences, Inc. (NASDAQ: CLRB), a clinical-stage biopharmaceutical company focused on the discovery, development

and commercialization of drugs for the treatment of cancer, today announced positive data from its Phase 2 CLOVER-1 study in patients

with relapsed/refractory B-cell lymphomas. Additionally, the company announced the successful completion of its Phase 1 dose escalation

study. Data from the studies demonstrated activity in all indications tested: multiple myeloma (MM), diffuse large B-cell lymphoma

(DLBCL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), marginal zone

lymphoma (MZL), mantle cell lymphoma (MCL), and lymphoplasmacytic lymphoma/Waldenstrom's macroglobulinemia (LPL/WM).

CLR 131 achieved notable response rates

in patients with multiple myeloma - 34.5% overall response rate (ORR) over all therapeutic doses (n=33), and non-Hodgkin's

lymphoma (NHL) - 42% ORR over all doses (n=20) while maintaining a well-tolerated safety profile across all patients. Based upon

these positive results and corroborating data showing the potential to further improve upon current overall response rates and

durability of those responses, the study has been expanded to test a two-cycle dosing optimization regimen of CLR 131.

in the studies were heavily pre-treated, with multiple myeloma patients having a median of five prior treatment regimens (range:

3 to 17), which included immunomodulatory drugs, proteasome inhibitors and CD38 antibodies for the majority of patients. Additionally,

a majority of the patients (51%) were quad refractory or greater and 44% of all treated multiple myeloma patients were triple class

refractory. NHL patients in the study were also heavily pre-treated, having had a median of 3 prior lines of treatment (range,

1 to 9) with the majority of patients being refractory to rituximab and/or ibrutinib. In both groups, the patients had a median

age of 70 with a range of 51 to 86.

Relapsed/refractory multiple myeloma patients

were treated with three different doses (<50mCi, ~50mCi and ~75mCi total body dose (TBD)); the <50mCi total body dose was

a deliberately planned sub-therapeutic dose. Patients who received the highest dose of CLR 131 showed a 42.8% ORR, and those who

received ~50mCi TBD had a 26.3% ORR with 100% of all evaluable patients (n=43) achieving clinical benefit (primary outcome measure)

as defined by having stable disease or better. 85.7% of multiple myeloma patients receiving the higher total body dose levels of

CLR 131 experienced tumor reduction. The 75mCi TBD demonstrated positive activity in both high-risk patients and triple class refractory

patients with a 50% and 33% ORR, respectively.

"The data reported today are very

promising and we believe the product profile for CLR 131 can improve further with the administration of a second cycle. These results

are even more impressive considering the challenging patient population tested, as all were heavily pre-treated with the vast majority

being refractory to their most recent therapy," said James Caruso, president and CEO of Cellectar Biosciences. "Based

upon these compelling data and the need for new and innovative treatment options for patients, we plan to execute upon a well-defined

and approvable regulatory path forward in a prioritized hematologic indication. We

hope that this potentially first-in-class PLE-targeted radiotherapeutic will provide a new and meaningful treatment option for

patients living with multiple myeloma and/or NHL."

The most frequently reported adverse events

in relapsed/refractory multiple myeloma patients were cytopenias, which followed a predictable course and timeline. The

most common grade 3 events at the highest dose (75mCi TBD) were hematologic toxicities including thrombocytopenia (65%), neutropenia

(41%), leukopenia (30%), anemia (24%) and lymphopenia (35%). No patients experienced cardiotoxicities, neurological toxicities,

infusion site reactions, peripheral neuropathy, allergic reactions, cytokine release syndrome, keratopathy, renal toxicities, or

changes in liver enzymes. The safety and tolerability profile in patients with relapsed/refractory NHL was the same except for

fewer cytopenias of any grade.

In addition to these findings, subtype

assessments were completed in the r/r B-cell NHL patients. Patients with DLBCL demonstrated a 30% response rate with one patient

achieving a complete response (CR), which continues at nearly 24 months post-treatment. The response rate for CLL/SLL/MZL patients

was 33%. Only two mantle cell patients were enrolled, with stable disease as the best response.

Current data from the company's Phase

2 CLOVER-1 clinical study show that four LPL/WM patients demonstrated 100% ORR with one patient achieving a complete response which

continues at nearly 27 months. This may represent an important improvement in the treatment of relapsed/refractory LPL/WM as no

approved or late-stage development treatments for second- and third-line patients have reported a complete response. LPL/WM is

a rare, indolent and incurable form of non-Hodgkin's lymphoma that is comprised of a niche patient population in need of

new and better treatment options.

patients who have failed the current standard of care treatments for any of these indications, there is a need for additional treatment

options," said lead study investigator Sikander Ailawadhi, M.D., Division of Hematology/Oncology, Department of Internal

Medicine, Mayo Clinic, Jacksonville, Florida. He added, "These data are impressive, especially in these very difficult to

treat patient populations. CLR 131 offers a very attractive safety and efficacy profile."

Summary of Results by Total Body Dose

Conference Call Details

The management team will host a conference

call for investors today, Wednesday, February 19 at 10:30 am Eastern Time to review the results and data from both the Phase 2

CLOVER-1 study and the Phase 1 r/r MM dose escalation study. The call will also include a presentation from lead investigator,

Dr. Sikander Ailawadhi, M.D. Conference call, webcast and post-conference call replay details are as follows:

Webcast: http://bit.ly/2uNAGWY

A webcast replay of the event will

be available following the live event on the Events section of the Cellectar website.

About the Phase 2 CLOVER-1 Study

Phase 2 study of CLR 131 being conducted in approximately 10 leading cancer centers in the United States in patients with relapsed/refractory

B-cell hematologic cancers. The hematologic cancers being studied include multiple myeloma (MM), chronic lymphocytic leukemia/small

lymphocytic lymphoma (CLL/SLL), lymphoplasmacytic lymphoma/ Waldenstrom's macroglobulinemia (LPL/WM), marginal zone lymphoma

(MZL), mantle cell lymphoma (MCL), and diffuse large B-cell lymphoma (DLBCL).

enroll up to 80 patients with its primary endpoint being clinical benefit response (CBR), which is defined as the proportion of

MM patients within three months following the initial infusion of CLR 131 with stringent complete response, complete response,

very good partial response, partial response and stable disease per International Myeloma Working Group criteria, or the proportion

of lymphomas patients (CLL/SLL, LPL, MZL, MCL, and DLBCL) within three months following the initial infusion of CLR 131 with CR,

PR and SD per the Lugano classification CT-based response criteria. Additional endpoints include overall response rate (ORR), progression

free survival (PFS), median overall survival (OS) and other markers of efficacy. Patients were treated with three different doses

(<50mCi, ~50mCi and ~75mCi total body dose) administered in either a single 30-minute infusion or two 30-minute infusions at

day 1 and day 7 ( 1), with the option for a second dose cycle approximately 75-180 days later.

results and corroborating data showing the potential to further improve upon the current overall response rates and durability

of those responses, the study has been expanded to test a two-cycle dosing optimization regimen of CLR 131. Patients will be administered

a two-cycle regimen with a total of four infusions, to be administered on day 1 and day 15 ( 1) and again on day 57

awarded approximately $2 million in non-dilutive grant funding from the National Cancer Institute to help fund the study. More

information about the study, including eligibility requirements, can be found at www.clinicaltrials.gov,

reference NCT02952508.

About the Phase 1 r/r MM Dose Escalation Study

The Phase 1 multicenter, open-label, dose-escalation study is

designed to evaluate the safety and tolerability of CLR 131 administered as a 30-minute I.V. infusion, either as a single bolus

dose or as two fractionated doses. The r/r multiple myeloma patients in this study received doses ranging from 25mCi to ~75mCi

total body dose. To date, an independent Data Monitoring Committee determined that all doses have been safe and well-tolerated