To The Editor:

SARS-CoV-2 (COVID-19) is a life-threatening disease that has rapidly spread around the world, reaching a mortality rate of > 4.7 million. Cancer patients are at increased risk of COVID-19 complications, and those with hematological malignancies have a more severe infection course than patients with solid tumors. Among hospitalized COVID-19 patients, those with blood cancer have a 2-fold higher death risk, demonstrating 28-day mortality of ~40%.¹

Multiple myeloma (MM) is associated with significantly impaired humoral and cellular immunity, and novel anti-MM therapies may further affect the immune system. These factors contribute to diminished immune response to various types of pathogens, including viral respiratory tract infections. Several large studies demonstrate inferior COVID-19 outcomes in patients with plasma cell neoplasms compared with general population.^{2, 3}

Devastating effects of SARS-CoV-2 pandemic resulted in unprecedented efforts to develop anti-COVID-19 vaccines. To date, two mRNA vaccines (BNT162b2 [Pfizer], mRNA-1273 [Moderna]) are approved by the FDA based on their high anti-COVID-19 protection, as evidenced by phase-3 trials, which included a very limited number of patients with blood cancers.

To induce optimal postvaccination immunity, an intact host immune status, in terms of antigen presentation, B- and T-cell activation, and plasma B-cell antibody generation, is required. Hence, hosts lacking functional immune cells may be incapable of producing a full-range response to SARS-CoV-2 vaccines. Yet, most experts recommend vaccination of immunocompromised patients as long as the vaccine is safe, even if the expected protection is decreased.

The current noninterventional single-center prospective study evaluated serological responses to two doses of BNT162b2 (administered 21 days apart) and the persistence of these responses in newly diagnosed and pretreated MM and light chain (AL) amyloid patients, recruited between 1/2021 and 4/2021 upon signing informed consent.

Based on the Guidance by the International Myeloma Society, in patients with active progressive MM, ongoing anti-MM therapy was not stopped because of vaccination. In patients with stable disease, treatment was interrupted 7 days before the first dose and reintroduced 7 days after the second dose. If a long pause was too risky, the first and second vaccine doses were administered 2–7 days post the last dose of anti-MM therapy and up to 10 days before the next MM-therapy dose. Lenalidomide monotherapy was not interrupted. Intravenous immunoglobulin (IVIg) was stopped 14–28 days before the first vaccine dose and reintroduced ≥ 14 days after the second dose.

According to the study protocol, serology tests are performed 1, 3, 6, and 12 months after second vaccination. To date, tests have been conducted 1 month (±1 week) and 3 months (±2 weeks) after the second BNT162b2 dose, using the SARS-CoV-2 IgG II Quant assay (Abbott©). The result is considered positive if the IgG level is ≥ 150 AU/mL, undetermined if the IgG level is between 50 and 150 AU/mL, and negative if it is < 50 AU/mL.

Patient demographics, comorbidities, hematological disease characteristics, anti-cancer treatment, disease activity, and laboratory data prevaccination were collected from medical records. Vaccination side effects were recorded. All patients were followed for symptomatic COVID-19 at least 1 week post-second vaccination. Patient serological responses were compared with those of the control group comprising Rambam employees without myeloma (1:3 ratio), matched by sex and age. Descriptive statistics were performed for all evaluated parameters. A logistic regression model was employed to predict a positive serological result based on several independent parameters.

The study included 186 patients: 10 with newly diagnosed MM, 168 with MM, and 8 with AL amyloid, either on active anti-MM therapy (n = 141 [80%]) or previously treated. Patients received a median of two lines of therapy (range 1–8). Based on the common practice, 23 patients (13%) were treated with IVIg due to hypogammaglobulinemia and recurrent severe bacterial infections.

One month after second vaccination (mean 33.93 ± 7.533 days), 176 patients (94%) underwent serological evaluation, with results categorized as negative, undetermined, and positive in 36 (20%), 11 (7%), and 129 (73%) patients, respectively. In univariate analysis, older age at vaccination was associated with negative serological response 1 month after second vaccination (p = .043). Gender, smoking, body mass index, and comorbidities (hypertension, diabetes mellitus, and ischemic heart disease) did not influence the response (Table S1). Patients on active anti-MM therapies and those who were heavily pretreated (average of 3.58 vs. 1.58 lines of therapy), particularly patients receiving anti-CD38 immunotherapy, displayed higher frequency of negative response (Table 1). Patients with negative results presented with lower lymphocyte, hemoglobin, albumin, and IgG levels than those who developed serological response (Table 1). Among patients with negative response, 41.7% were treated with IVIg, while among those with a positive result, 5.4% received IVIg (p < .0001). Previous autologous stem cell transplantation and disease activity at vaccination did not influence the response.

In multivariate analysis, older age at vaccination (p = .019), multiple lines of anti-MM treatment (p = .004), and anti-CD38 immunotherapy (p = .01) predicted a negative serological response. Three months after second vaccination, 129/186 patients (69%) underwent serological evaluation. The response was negative in 34 (26%), undetermined—in 19 (15%) and positive in 76 (59%) individuals. Results of tests performed at both time points were available for 120 patients. Among the 90 patients seropositive 1 month after second vaccination and re-evaluated at 3 months, 68 (76%) remained seropositive. Notably, 2/25 patients, seronegative at 1 month, got infected with COVID-19 and became seropositive at 3 months. The rate of positive responses was significantly lower in the patient cohort compared with controls, both 1 and 3 months after second vaccination, equating to 90/120 (75%) versus 357/360 (99.2%; p < .001) and 68/120 (56%) versus 355/360 (98.6%; p < .0001). Vaccination-related side effects in patients included: local pain (10%), fever (1.7%), and muscle pain (2.8%). Twelve patients (6.4%) experienced myeloma progression during the first month after the second vaccine dose.

A subanalysis of 137 patients on active anti-MM therapy demonstrated that 1 month after second vaccination, 35 (25%) patients had negative, 11 (8%)—undetermined and 91 (66%)—positive serological results. Among 50 patients, receiving anti-CD38 therapy during vaccination, results were negative in 38% and positive in 54% of individuals (p = .007). Serological responses at both 1 and 3 months post-second vaccination were evaluated in 95 patients on active therapy, with positive results documented in 65 (68%) and 48 (50.5%) of them, respectively.

The influence of anti-CD38 immunotherapy was further emphasized in the quantitative assessment of neutralizing antibody titers postvaccination. One month after second vaccination, the median (25%–75%) titers of neutralizing antibodies were: 4149 (887–10 432) in 39 patients not on active therapy, 895 (110–7488) in 87 patients on active therapy excluding anti-CD38 agents, and 193 (17.5–744.5) in 50 patients receiving anti-CD38 therapy. At 3 months post-second vaccination, the corresponding values were: 912.5 (232–2234) in 32, 190 (54–2226) in 59, and 96 (9–347) in 39 patients, respectively (Figure S1).

At the time of analyses, most patients were 6 months after second vaccination. Four of them developed COVID-19 at least 1 week after the last vaccine dose (1 died of this disease, 1 had a severe course, but recovered, 2 had mild disease). Two patients displayed a negative serological result 1 month after second vaccination, which converted to positive following their COVID-19 resolution. One patient was seropositive at 1 month after vaccination and his disease course was mild. The patient who died did not undergo serological evaluation.

High COVID-19-associated mortality among myeloma patients calls for most efficient measures aiming to prevent virus contamination. mRNA anti-COVID-19 vaccines have proved highly effective in general adult population; however, immunocompromised patients have been extremely underrepresented in those clinical trials.

Seroconversion is a useful tool in predicting vaccine efficacy.⁴ While clinical trials of mRNA anti-COVID-19 vaccines demonstrate an association of seroconversion with disease prevention in general population, corresponding data regarding patients with hematological malignancies are limited.

Results of the current study show that a significant portion of MM patients develops serological response to anti-COVID-19 vaccines. Comparison of our findings with those of the UK study⁵ demonstrates a significant increase in the number of positive serological results after the second vaccine dose (56% in the UK MM cohort after one vaccination versus 73% in our cohort after two vaccinations). These data point to the importance of a full vaccination course (2 doses) in immunocompromised patients.

Among our patients, those who received more lines of anti-MM treatment and those on active therapy at the time of vaccination, particularly patients receiving anti-CD38 therapy, demonstrated a lower rate of positive serological results. Notably, one patient treated with daratumumab had a negative serological response after 1 and 3 months from second vaccination. Six months after second vaccination, while she was 3 months off-therapy, her serological result became positive, with no evidence of COVID-19 infection. This may suggest that the humoral decay associated with daratumumab could be temporary and the immune response to the vaccination may improve after deferral of anti-CD38 therapy. Our finding could contribute to the emerging consideration for temporary discontinuation of anti-CD38 therapy at the time of COVID-19 pandemic spike in patients with good response to anti-MM therapy.

Anti-myeloma agents are known to affect the function of T- and B-cells and the immune microenvironment. Thus, it is not surprising that heavily pretreated myeloma patients exhibit reduced ability to produce an effective immune response.

Additionally, MM patients frequently present with immunoparesis, which is commonly managed with IVIg if accompanied with recurrent infections. In our cohort, hypogammaglobulinemia and IVIg treatment are found to be significantly associated with decreased rates of seropositive results that might be attributed to reduced humoral response related to both these factors.

In the present study, the durability of patient serological response is reduced compared with that in controls, as demonstrated by a significantly higher rate of conversion from a seropositive to seronegative result 3 months after second vaccination. Hence, immunocompromised individuals may need a booster vaccine dose to enhance their response.⁶

Our study has several limitations. Levels of IgG antibodies developing in response to vaccination do not reflect the full range of immune response. Cellular immunity analyses (e.g., T-cell subpopulations, NK cells, etc.) could add to our understanding of the protective effect of vaccination. Furthermore, infection rates significantly decreased during the study period owing to the accomplishment of anti-COVID-19 vaccination. This precluded the assessment of the protective effect of such vaccination in MM patients.

The current study demonstrates that the majority of MM and AL amyloid patients generate reliable humoral immune response after two vaccinations with BNT162b2. Multiple lines of anti-MM treatment and anti-CD38 immunotherapy are associated with a negative serological response. Despite their vaccination, patients who have not developed serological response may remain unprotected from COVID-19, although other immune mechanisms might mediate some protection in such cases. To achieve a more efficient and durable serological response in MM patients, the currently applied vaccination schedule, dosage, and the number of doses administered may need to be modified. Serological monitoring could be used to guide the timing of vaccination boost. A longer follow-up is required to assess the degree of protection provided by anti-COVID-19 vaccination. Further clinical trials are warranted to determine the optimal regimen of vaccine administration in this vulnerable patient population.

致编辑：

SARS-CoV-2 (COVID-19) 是一种危及生命的疾病，已在世界范围内迅速传播，死亡率超过 470 万。癌症患者发生 COVID-19 并发症的风险增加，血液系统恶性肿瘤患者的感染病程比实体瘤患者更严重。在住院的 COVID-19 患者中，血癌患者的死亡风险高出 2 倍，表明 28 天死亡率约为 40%。¹

多发性骨髓瘤 (MM) 与体液和细胞免疫显着受损有关，新的抗 MM 疗法可能会进一步影响免疫系统。这些因素导致对各种病原体（包括病毒性呼吸道感染）的免疫反应减弱。几项大型研究表明，与普通人群相比，浆细胞肿瘤患者的 COVID-19 结果较差。^2、3

SARS-CoV-2 大流行的破坏性影响导致了开发抗 COVID-19 疫苗的空前努力。迄今为止，FDA 批准了两种 mRNA 疫苗（BNT162b2 [Pfizer]、mRNA-1273 [Moderna]），因为它们具有高度的抗 COVID-19 保护作用，3 期试验证明了这一点，其中包括数量非常有限的血癌患者。

为了诱导最佳的接种后免疫，需要在抗原呈递、B 细胞和 T 细胞活化以及血浆 B 细胞抗体生成方面保持完整的宿主免疫状态。因此，缺乏功能性免疫细胞的宿主可能无法对 SARS-CoV-2 疫苗产生全方位反应。然而，只要疫苗是安全的，即使预期的保护作用降低，大多数专家仍建议对免疫功能低下的患者进行疫苗接种。

当前的非干预性单中心前瞻性研究评估了对两剂 BNT162b2（相隔 21 天给药）的血清学反应以及这些反应在新诊断和预处理的 MM 和轻链 (AL) 淀粉样蛋白患者中的持续性，在 1/2021 和 4 之间招募/2021 签署知情同意书。

根据国际骨髓瘤协会的指南，对于活动性进行性多发性骨髓瘤患者，正在进行的抗多发性骨髓瘤治疗并未因疫苗接种而停止。对于病情稳定的患者，在第一次给药前 7 天中断治疗，并在第二次给药后 7 天重新开始治疗。如果长时间停顿风险太大，则在最后一剂抗 MM 治疗后 2-7 天和下一次 MM 治疗前 10 天接种第一剂和第二剂疫苗。来那度胺单药治疗没有中断。在第一剂疫苗接种前 14-28 天停止静脉注射免疫球蛋白 (IVIg)，并在第二剂接种后≥14 天重新注射。

根据研究方案，在第二次接种疫苗后 1、3、6 和 12 个月进行血清学测试。迄今为止，已使用 SARS-CoV-2 IgG II Quant 检测 (Abbott©) 在第二次 BNT162b2 剂量后 1 个月（±1 周）和 3 个月（±2 周）进行了测试。如果 IgG 水平 ≥ 150 AU/mL，则结果被认为是阳性，如果 IgG 水平在 50 和 150 AU/mL 之间则不确定，如果 < 50 AU/mL，则结果为阴性。

从医疗记录中收集患者人口统计学、合并症、血液学疾病特征、抗癌治疗、疾病活动和实验室接种数据。记录疫苗接种的副作用。在第二次接种疫苗后至少 1 周，对所有患者进行有症状的 COVID-19 随访。将患者血清学反应与对照组的血清学反应进行比较，对照组包括无骨髓瘤的 Rambam 员工（比例为 1:3），按性别和年龄匹配。对所有评估参数进行描述性统计。基于几个独立参数，采用逻辑回归模型来预测阳性血清学结果。

该研究包括 186 名患者：10 名新诊断的 MM、168 名 MM 和 8 名 AL 淀粉样蛋白，他们接受了积极的抗 MM 治疗（n = 141 [80%]）或以前接受过治疗。患者接受了中位数的两条治疗线（范围 1-8）。根据惯例，23 名患者 (13%) 由于低丙种球蛋白血症和复发性严重细菌感染而接受 IVIg 治疗。

第二次疫苗接种后 1 个月（平均 33.93 ± 7.533 天），176 名患者 (94%) 接受了血清学评估，结果分为阴性、未确定和阳性，分别为 36 (20%)、11 (7%) 和 129 (73 %) 患者。在单变量分析中，接种疫苗的年龄较大与第二次接种疫苗后 1 个月的阴性血清学反应相关（p = .043）。性别、吸烟、体重指数和合并症（高血压、糖尿病和缺血性心脏病）不影响反应（表 S1）。接受积极抗 MM 治疗的患者和接受过大量预处理的患者（平均 3.58 线对 1.58 线治疗），特别是接受抗 CD38 免疫治疗的患者，显示出较高的阴性反应频率（表 1）。结果阴性的患者淋巴细胞、血红蛋白、白蛋白和 IgG 水平低于出现血清学反应的患者（表 1）。在反应阴性的患者中，41.7% 接受了 IVIg，而在阳性结果的患者中，5.4% 接受了 IVIg ( p  < .0001)。以前的自体干细胞移植和疫苗接种时的疾病活动不影响反应。

在多变量分析中，接种疫苗的年龄较大 ( p  = .019)、多线抗 MM 治疗 ( p  = .004) 和抗 CD38 免疫疗法 ( p = .01) 预测血清学反应为阴性。第二次疫苗接种三个月后，129/186 名患者 (69%) 接受了血清学评估。34 人 (26%) 的反应为阴性，19 人 (15%) 的反应未定，76 人 (59%) 的反应为阳性。在这两个时间点进行的测试结果可用于 120 名患者。在第二次接种疫苗后 1 个月并在 3 个月时重新评估的 90 名患者中，有 68 名 (76%) 仍呈血清阳性。值得注意的是，2/25 的患者在 1 个月时血清阴性，感染了 COVID-19 并在 3 个月时变为血清阳性。在第二次接种疫苗后 1 个月和 3 个月，患者队列中的阳性反应率显着低于对照组，相当于 90/120 (75%) 与 357/360 (99.2%；p  < .001) 和 68/ 120 (56%) 对 355/360 (98.6%;p  < .0001）。患者接种疫苗相关的副作用包括：局部疼痛 (10%)、发热 (1.7%) 和肌肉疼痛 (2.8%)。12 名患者 (6.4%) 在第二次疫苗接种后的第一个月内经历了骨髓瘤进展。

对 137 名接受主动抗 MM 治疗的患者进行的亚组分析表明，在第二次疫苗接种后 1 个月，35 名 (25%) 患者出现阴性、11 名 (8%) 未确定和 91 名 (66%) 阳性血清学结果。在接种疫苗期间接受抗 CD38 治疗的 50 名患者中，38% 的结果为阴性，54% 的个体结果为阳性 ( p  = .007)。对 95 名接受积极治疗的患者在第二次接种疫苗后 1 个月和 3 个月时的血清学反应进行了评估，其中分别记录了 65 名 (68%) 和 48 名 (50.5%) 的阳性结果。

在疫苗接种后中和抗体滴度的定量评估中进一步强调了抗 CD38 免疫疗法的影响。第二次接种后 1 个月，中和抗体滴度的中位数 (25%–75%) 为：39 名未接受积极治疗的患者为 4149 (887-10 432)，87 名接受积极治疗的患者（不包括抗病毒治疗）为 895 (110-7488) -CD38 药物，以及 50 名接受抗 CD38 治疗的患者中的 193 (17.5–744.5)。在第二次接种疫苗后 3 个月，相应的值分别为：32 人为 912.5（232-2234），59 人为 190（54-2226），39 人为 96（9-347）（图 S1）。

在分析时，大多数患者在第二次接种疫苗后 6 个月。其中 4 人在最后一次接种疫苗后至少 1 周出现 COVID-19（1 人死于该病，1 人病程严重，但康复了，2 人病情较轻）。两名患者在第二次接种疫苗 1 个月后显示阴性血清学结果，在其 COVID-19 解决后转为阳性。1 例患者在接种疫苗后 1 个月呈血清阳性，病程较轻。死亡患者未进行血清学评估。

骨髓瘤患者中与 COVID-19 相关的高死亡率要求采取最有效的措施来防止病毒污染。mRNA 抗 COVID-19 疫苗已被证明对一般成年人群非常有效；然而，免疫功能低下的患者在这些临床试验中的代表性极低。

血清转化是预测疫苗效力的有用工具。⁴虽然 mRNA 抗 COVID-19 疫苗的临床试验表明血清转化与一般人群的疾病预防有关，但有关血液系统恶性肿瘤患者的相应数据有限。

目前的研究结果表明，很大一部分 MM 患者对抗 COVID-19 疫苗产生血清学反应。将我们的发现与英国研究^{5 的}结果进行比较表明，第二次疫苗接种后血清学阳性结果的数量显着增加（英国 MM 队列接种一次后为 56%，而我们的队列接种两次后为 73%）。这些数据表明对免疫功能低下的患者进行完整的疫苗接种课程（2 剂）的重要性。

在我们的患者中，那些在接种疫苗时接受更多抗 MM 治疗的患者和正在接受积极治疗的患者，特别是接受抗 CD38 治疗的患者，血清学阳性率较低。值得注意的是，一名接受达雷妥尤单抗治疗的患者在第二次接种疫苗后 1 个月和 3 个月后出现阴性血清学反应。第二次接种疫苗 6 个月后，在停药 3 个月时，她的血清学结果呈阳性，没有感染 COVID-19 的证据。这可能表明与达雷妥尤单抗相关的体液衰减可能是暂时的，并且在推迟抗 CD38 治疗后，对疫苗接种的免疫反应可能会有所改善。

已知抗骨髓瘤药物会影响 T 细胞和 B 细胞的功能以及免疫微环境。因此，严重预处理的骨髓瘤患者表现出产生有效免疫反应的能力降低也就不足为奇了。

此外，MM 患者经常出现免疫麻痹，如果伴有反复感染，通常用 IVIg 进行治疗。在我们的队列中，发现低丙种球蛋白血症和 IVIg 治疗与血清阳性结果率降低显着相关，这可能归因于与这两个因素相关的体液反应降低。

在本研究中，与对照组相比，患者血清学反应的持久性降低，如第二次接种疫苗后 3 个月从血清阳性结果转为血清阴性结果的转化率显着提高所证明的那样。因此，免疫功能低下的个体可能需要加强疫苗剂量以增强其反应。⁶

我们的研究有一些局限性。接种疫苗后产生的 IgG 抗体水平并不能反映免疫反应的全部范围。细胞免疫分析（例如，T 细胞亚群、NK 细胞等）可以增加我们对疫苗接种保护作用的理解。此外，由于完成了抗 COVID-19 疫苗接种，感染率在研究期间显着下降。这排除了对这种疫苗接种对 MM 患者的保护作用的评估。

目前的研究表明，大多数 MM 和 AL 淀粉样蛋白患者在两次 BNT162b2 疫苗接种后产生可靠的体液免疫反应。多线抗 MM 治疗和抗 CD38 免疫治疗与阴性血清学反应相关。尽管接种了疫苗，但未出现血清学反应的患者可能仍无法抵御 COVID-19，尽管在这种情况下其他免疫机制可能会起到一定的保护作用。为了在 MM 患者中实现更有效和持久的血清学反应，可能需要修改当前应用的疫苗接种计划、剂量和给药次数。血清学监测可用于指导疫苗接种加强的时机。需要更长时间的随访来评估抗 COVID-19 疫苗接种提供的保护程度。